In-vitro analysis of the microbicidal activity of 6 contact lens care solutions

PubMed Central

2012-01-01

Background Contact lens-related infections are often associated with inadequate contact lens hygiene, and therefore, contact lens care products should be able to sufficiently minimise the amount of pathogens that are responsible for these infections. In 2001, the EN ISO 14729 was introduced to ensure adequate disinfection efficacy of contact lens care solutions, but this norm has recently been criticised. Methods In this study, six frequently used contact lens care solutions were retested according to the Stand Alone Test of the EN ISO 14729 (2001). The Stand Alone Test is a quantitative suspension test. In addition, the products were tested in a modified setting adding an organic load. The load was a mixture of human blood serum, lysozyme, and mucine, which resembles tear fluid. Results The criteria of the Stand Alone Test recommended in EN ISO 14729 were only met by Aosept Plus. This 3% hydrogen-peroxide-based contact lens care solution attained a reduction factor of > 5 log units for bacteria and > 4 for fungi in all cases. Two further contact lens care solutions, Blue Vision and Optifree Replenish, met the criteria of a reduction factor of > 3 log units for bacteria and > 1 log unit for fungi, but only in the presence of artificial tear fluid. The three remaining products did not exhibit adequate disinfecting efficacy, at least against one of the tested microorganisms. Conclusions Through the observation that the artificial tear fluid used in this study influences the disinfecting efficacy of contact lens care solutions, especially that of multi-purpose solutions, in a different way than does albumin, mucine, or even the organic load suggested in EN ISO 14729, it becomes obvious that the test conditions in the EN ISO 14729 should be revised in order to create more realistic conditions, e.g., by using a more realistic artificial tear fluid. Furthermore, we suggest adapting the EN ISO 14729 to the European test hierarchy for chemical disinfectants and antiseptics, which consists of three test phases and also requests meeting stricter criteria in order to pass the test. Unless the test conditions guarantee a sufficient reduction of potential pathogens, the risk of contact lens-related microbial keratitis and other infections will remain for the users. PMID:23033880

Bacterial transmission from lens storage cases to contact lenses-Effects of lens care solutions and silver impregnation of cases.

PubMed

Vermeltfoort, Pit B J; Hooymans, Johanna M M; Busscher, Henk J; van der Mei, Henny C

2008-10-01

The killing efficacies of multipurpose lens care solutions on planktonic and biofilm bacteria grown in polypropylene contact lens storage cases with and without silver impregnation and effects on bacterial transmission from storage cases to silicone hydrogel contact lenses were investigated. For transmission studies, biofilms of Staphylococcus aureus 835 or Pseudomonas aeruginosa no. 3 were grown on lens storage cases and incubated with a contact lens in different multipurpose lens care solutions (Opti-Free(R)Express(R), ReNu(R) MultiPlus(R), and SoloCare Aquatrade mark) or 0.9% NaCl. In addition, planktonic bacteria were directly suspended in multipurpose solutions and their killing efficacies were determined. The numbers of transmitted live and dead bacteria on the lenses were measured using a combination of plate counting and fluorescence microscopy. The highest killing efficacies were shown by Opti-Free(R) Express(R) for planktonic as well as for biofilm bacteria. Silver impregnation of lens cases in combination with the prescribed solution increased the killing efficacy for P. aeruginosa in biofilms, whereas effects for S. aureus were minor. Lowest numbers of live and dead bacteria were transmitted to a lens in Opti-Free(R) Express(R) multipurpose solution, with no significant differences between lens types and no effects of silver impregnation. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008. (c) 2008 Wiley Periodicals, Inc.

Antimicrobial Efficacy of Contact Lens Care Solutions Against Neutrophil-Enhanced Bacterial Biofilms

PubMed Central

Hinojosa, Jorge A.; Patel, Naiya B.; Zhu, Meifang; Robertson, Danielle M.

2017-01-01

Purpose Neutrophil-derived extracellular debris has been shown to accelerate bacterial biofilm formation on hydrogel and silicone hydrogel contact lens surfaces compared to lenses inoculated with bacteria alone. The purpose of this study was to evaluate the disinfection efficacy of four standard commercial contact lens cleaning regimens against neutrophil-enhanced bacterial biofilms formed on silicone hydrogel contact lenses. Methods Four reference strains were used: Pseudomonas aeruginosa, Serratia marcescens, Stenotrophomonas maltophilia, and Staphylococcus aureus. Human neutrophils were isolated from peripheral blood by venipuncture. Unworn Lotrafilcon B lenses were incubated overnight in each respective strain with stimulated neutrophils. Contact lenses were then cleaned using one of four contact lens care solutions according to manufacturer instructions. Bacterial viability was assessed by colony counts and confocal microscopy. Volume of residual debris on lens surfaces after cleaning was quantified using IMARIS software. Results All four solutions tested showed effective antimicrobial activity against each bacterial strain; however, substantial amounts of nonviable bacteria and cellular debris remained on the lens surface despite concomitant digital cleaning. Conclusions Necrotic cellular debris that accumulates under the posterior lens surface during wear of an inoculated contact lens is not fully removed during routine cleaning and disinfection. Translational Relevance The accumulation of residual cellular debris on the contact lens surface may contribute to new colonization of the lens and represents a significant risk factor for a contact lens–related adverse event. Additional studies are needed to correlate these findings with risk for corneal infiltrative and/or infectious events in a standard animal model. PMID:28473944

Increased resistance of contact lens related bacterial biofilms to antimicrobial activity of soft contact lens care solutions

PubMed Central

Szczotka-Flynn, Loretta B.; Imamura, Yoshifumi; Chandra, Jyotsna; Yu, Changping; Mukherjee, Pranab K.; Pearlman, Eric; Ghannoum, Mahmoud A.

2014-01-01

PURPOSE To determine if clinical and reference strains of Pseudomonas aeruginosa, Serratia marcescens, and Staphylococcus aureus form biofilms on silicone hydrogel contact lenses, and ascertain antimicrobial activities of contact lens care solutions. METHODS Clinical and American Type Culture Collection (ATCC) reference strains of Pseudomonas aeruginosa, Serratia marcescens, and Staphylococcus aureus were incubated with lotrafilcon A lenses under conditions that facilitate biofilm formation. Biofilms were quantified by quantitative culturing (colony forming units, CFUs), and gross morphology and architecture were evaluated using scanning electron microscopy (SEM) and confocal microscopy. Susceptibilities of the planktonic and biofilm growth phases of the bacteria to five common multipurpose contact lens care solutions and one hydrogen peroxide care solution were assessed. RESULTS P. aeruginosa, S. marcescens, and S. aureus reference and clinical strains formed biofilms on lotrafilcon A silicone hydrogel contact lenses, as dense networks of cells arranged in multiple layers with visible extracellular matrix. The biofilms were resistant to commonly used biguanide preserved multipurpose care solutions. P. aeruginosa and S. aureus biofilms were susceptible to a hydrogen peroxide and a polyquaternium preserved care solution, whereas S. marcescens biofilm was resistant to a polyquaternium preserved care solution but susceptible to hydrogen peroxide disinfection. In contrast, the planktonic forms were always susceptible. CONCLUSIONS P. aeruginosa, S. marcescens, and S. aureus form biofilms on lotrafilcon A contact lenses, which in contrast to planktonic cells, are resistant to the antimicrobial activity of several soft contact lens care products. PMID:19654521

The influence of lens care systems on eyelid tissue changes during silicone hydrogel contact lens wear.

PubMed

Guillon, Michel; Maissa, Cécile; Wong, Stéphanie; Patel, Trisha; Garofalo, Renée

2018-04-14

To compare the effects of a hydrogen peroxide (H 2 O 2 )-based lens care solution and a polyhexamethylene biguanide (PHMB) multi-purpose solution on the eyelids when used with silicone hydrogel (SiHy) contact lenses. A total of 74 symptomatic wearers of ACUVUE ® OASYS ® (senofilcon A; n = 39) or PureVision ® (balafilcon A; n = 35) contact lenses were randomised 1:1 to either CLEAR CARE ® Cleaning & Disinfecting Solution or renu ® fresh™ multi-purpose solution (n = 37 each). Assessments of hyperaemia, papillae and lid margin staining of eyelid tissue were evaluated subjectively by a masked investigator at enrolment (with the subjects' habitual SiHy contact lenses and PHMB-preserved care systems), at dispensing visit (when no lenses were worn) and at 3-months' follow-up. There were no differences in eyelid assessments between the two lens care groups at dispensing visit (p = 0.086 to 0.947). After 3 months, the papillae response was significantly less marked with H2O2-based solution than with PHMB-based solution (p = 0.017). Lid hyperaemia (p < 0.001) and papillae (p = 0.002) were also significantly reduced. Although lid hyperaemia was also reduced with PHMB-based solution (p < 0.001), there was no concurrent decrease in papillae response (p = 0.051). No improvements were found in eyelid margin staining either over time or between the two lens care groups. In symptomatic contact lens wearers, a H 2 O 2 -based lens care solution used with senofilcon A and balafilcon A lenses was better tolerated by eyelid tissues than was a PHMB-based solution and led to a decrease in clinical markers of eyelid inflammation. Copyright © 2018 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Microbial contamination of soft contact lenses & accessories in asymptomatic contact lens users

PubMed Central

Thakur, Deeksha V.; Gaikwad, Ujjwala N.

2014-01-01

Background & objectives: With increasing use of soft contact lenses the incidence of contact lens induced infections is also increasing. This study was aimed to assess the knowledge of new and existing contact lens users about the risk of microbial contamination associated with improper use and maintenance of contact lenses, type of microbial flora involved and their potential to cause ophthalmic infections. Methods: Four samples each from 50 participants (n=200) were collected from the lenses, lens care solutions, lens care solution bottles and lens cases along with a questionnaire regarding their lens use. The samples were inoculated onto sheep blood agar, Mac Conkey's agar and Sabouraud's dextrose agar. Organisms were identified using standard laboratory protocols. Results: Overall rate of microbial contamination among the total samples was 52 per cent. The most and the least contaminated samples were found to be lens cases (62%) and lens care solution (42%), respectively. The most frequently isolated contaminant was Staphylococcus aureus (21%) followed by Pseudomonas species (19.5%). Majority (64%) of the participants showed medium grade of compliance to lens cleaning practices. Rate of contamination was 100 and 93.75 per cent respectively in those participants who showed low and medium compliance to lens care practices as compared to those who had high level of compliance (43.75%) (P<0.05). Interpretation & conclusions: Lens care practices amongst the participants were not optimum which resulted into high level contamination. Hence, creating awareness among the users about the lens care practices and regular cleaning and replacements of lens cases are required. PMID:25297366

Comparative study of antibacterial and antifungal effects of rigid gas permeable contact lens disinfecting solutions.

PubMed

Kuzman, Tomislav; Kutija, Marija Barisić; Kordić, Rajko; Popović-Sui, Smiljka; Jandroković, Sonja; Skegro, Ivan; Pokupec, Rajko

2013-04-01

The aim of this study was to compare antimicrobial efficacy of rigid contact lens disinfecting solutions. We tested five commercially available solutions: Unique pH (Alcon Laboratories), Boston Advance (Polymer Technology Corp.), Nitilens Conditioner GP (Avizor), Total Care (AMO), Boston Simplus (Bausch&Lomb). Their efficacy to disinfect saline solution experimentally contaminated with American Type Culture Collection (ATCC): Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Candida albicans (ATCC 90028) and Staphylococcus epidermidis (isolated from our laboratory) was tested. All tested solutions reduced concentrations of bacteria and fungi below 1000 CFU/mL (Colony forming unit; reduction by 3 log and 1 log, respectively) after the 8 hours period. Overall, all contact lens care solutions showed good disinfecting activity against tested bacteria and fungi, with more variation in their antifungal than in antibacterial efficacy. Results of our study might be valuable when selecting appropriate solutions for non-compliant contact lens wearers.

The effects of contact lens materials on a multipurpose contact lens solution disinfection activity against Staphylococcus aureus.

PubMed

Shoff, Megan E; Lucas, Anne D; Brown, Jennifer N; Hitchins, Victoria M; Eydelman, Malvina B

2012-11-01

To determine the effect of 8 different lens materials on polyhexamethylene biguanide (PHMB) concentration in multipurpose solution (MPS) levels over time and to determine the effect of lenses on lens solution microbial efficacy over time. Silicone hydrogel lenses and conventional hydrogel lenses were soaked in polypropylene lens cases filled with contact lens MPS containing 1 ppm PHMB for 6, 12, 24, 72, and 168 hours. Cases filled with the same solution without lenses were controls. After each time period, solutions from cases with the 8 types of lenses and controls were assayed for activity against Staphylococcus aureus according to International Organization for Standardization-14729 with modifications. Solutions were analyzed for PHMB concentration at each time point. Some of the different lens materials significantly affected the PHMB concentration (P<0.0001) and the biocidal efficacy. Etafilcon A lenses significantly decreased PHMB levels after only 6 hours of lens soak time. The product lot of MPS used was also significant (P<0.0001). Enfilcon A, senofilcon A, and lotrafilcon B lenses did not significantly decrease PHMB levels. The efficacy of MPS was affected by some lens materials and PHMB concentration. Lens materials differ in their effect on PHMB concentration and the subsequent efficacy of the MPS. Over time, some lens materials can significantly reduce the PHMB concentration and the MPS's microbial activity against S. aureus.

21 CFR 886.5928 - Soft (hydrophilic) contact lens care products.

Code of Federal Regulations, 2011 CFR

2011-04-01

... (hydrophilic) contact lens. This includes all solutions and tablets used together with soft (hydrophilic) contact lenses and heat disinfecting units intended to disinfect a soft (hydrophilic) contact lens by means of heat. (b) Classification. Class II (Special Controls) Guidance Document: “Guidance for Industry...

21 CFR 886.5928 - Soft (hydrophilic) contact lens care products.

Code of Federal Regulations, 2012 CFR

2012-04-01

... (hydrophilic) contact lens. This includes all solutions and tablets used together with soft (hydrophilic) contact lenses and heat disinfecting units intended to disinfect a soft (hydrophilic) contact lens by means of heat. (b) Classification. Class II (Special Controls) Guidance Document: “Guidance for Industry...

21 CFR 886.5928 - Soft (hydrophilic) contact lens care products.

Code of Federal Regulations, 2013 CFR

2013-04-01

... (hydrophilic) contact lens. This includes all solutions and tablets used together with soft (hydrophilic) contact lenses and heat disinfecting units intended to disinfect a soft (hydrophilic) contact lens by means of heat. (b) Classification. Class II (Special Controls) Guidance Document: “Guidance for Industry...

21 CFR 886.5928 - Soft (hydrophilic) contact lens care products.

Code of Federal Regulations, 2014 CFR

2014-04-01

... (hydrophilic) contact lens. This includes all solutions and tablets used together with soft (hydrophilic) contact lenses and heat disinfecting units intended to disinfect a soft (hydrophilic) contact lens by means of heat. (b) Classification. Class II (Special Controls) Guidance Document: “Guidance for Industry...

Resistance of Acanthamoeba cysts to disinfection in multiple contact lens solutions.

PubMed

Johnston, Stephanie P; Sriram, Rama; Qvarnstrom, Yvonne; Roy, Sharon; Verani, Jennifer; Yoder, Jonathan; Lorick, Suchita; Roberts, Jacquelin; Beach, Michael J; Visvesvara, Govinda

2009-07-01

Acanthamoebae are free-living amoebae found in the environment, including soil, freshwater, brackish water, seawater, hot tubs, and Jacuzzis. Acanthamoeba species can cause keratitis, a painful vision-threatening infection of the cornea, and fatal granulomatous encephalitis in humans. More than 20 species of Acanthamoeba belonging to morphological groups I, II, and III distributed in 15 genotypes have been described. Among these, Acanthamoeba castellanii, A. polyphaga, and A. hatchetti are frequently identified as causing Acanthamoeba keratitis (AK). Improper contact lens care and contact with nonsterile water while wearing contact lenses are known risk factors for AK. During a recent multistate outbreak, AK was found to be associated with the use of Advanced Medical Optics Complete MoisturePlus multipurpose contact lens solution, which was hypothesized to have had insufficient anti-Acanthamoeba activity. As part of the investigation of that outbreak, we compared the efficacies of 11 different contact lens solutions against cysts of A. castellanii, A. polyphaga, and A. hatchetti (the isolates of all species were genotype T4), which were isolated in 2007 from specimens obtained during the outbreak investigation. The data, generated with A. castellanii, A. polyphaga, and A. hatchetti cysts, suggest that the two contact lens solutions containing hydrogen peroxide were the only solutions that showed any disinfection ability, with 0% and 66% growth, respectively, being detected with A. castellanii and 0% and 33% growth, respectively, being detected with A. polyphaga. There was no statistically significant difference in disinfection efficacy between the 11 solutions for A. hatchetti.

Contact lens complications.

PubMed

Suchecki, Jeanine K; Donshik, Peter; Ehlers, William H

2003-09-01

Complications associated with contact lenses range from mild to severe and occur with all lens modalities. Contact lens wear can cause a change in corneal physiology, which can lead to epithelial, stromal, and endothelial compromise. Other complications include lens deposition, allergic conjunctivitis, giant papillary conjunctivitis, peripheral infiltrates, microbial keratitis, and neovascularization. Pre-existing conditions can contribute to these complications, or they can occur in association with contact lens wear and care regimens. Patient-related factors, such as alteration of the recommended wearing or replacement schedules and noncompliance with recommended contact lens care regimens for economic reasons, convenience, or in error, contribute to contact lens-related complications and have led to difficulty in accurate determination of complication rates among the various lens wear modalities. Complications may require discontinuation of contact lenses, topical therapy, and changes in contact lens wearing schedules, materials, and care solutions. On initial lens fitting and follow-up evaluations, practitioners should review contact lens replacement and cleaning regimens with patients and discuss complications. To avoid serious complications, patients should be reminded to remove their contact lenses as soon as ocular irritation occurs, and to call their eye care practitioner immediately if symptoms persist.

How Could Contact Lens Wearers Be at Risk of Acanthamoeba Infection? A Review

PubMed Central

Ibrahim, Youhanna W.; Boase, David L.; Cree, Ian A.

2010-01-01

Contact lens wear is highly influential on the incidence of ulcerative keratitis worldwide, particularly in developed countries. The association between Acanthamoeba keratitis and contact lens wear is firmly established; it may account for up to 95% of the reported cases. Before the popularisation of soft contact lens wear, Acanthamoeba keratitis was extremely rare. In 2000 it was estimated that the number of contact lens wearers worldwide was about 80 million, out of whom 33 million were in the United States and 90% of them wore hydrogel soft lenses. Contact lens-related problems depend on many factors, such as lens material, wearing modality, lens hygiene, type of lens-caring solution, the degree of compliance of the lens user with lens wear and care procedures, lens overwear, sleeping in lenses, rate of changing lenses, and lens case hygiene. This paper is a thorough review of the literature aiming to highlight the role of one of the main risk factors of infectious keratitis, contact lens wear, and also to show the responsibility of lens users in aggravating this risk.

Experimental Contact Lens to Prevent Glaucoma-Induced Blindness

MedlinePlus

... By Sharon Reynolds Posted January 23, 2014 An experimental contact lens design releases a glaucoma medicine at a steady rate ... materials. Other designs have most often used a pre-made lens dipped in a drug solution, which ...

[Eyelid hygiene for contact lens wearers with blepharitis. Comparative investigation of treatment with baby shampoo versus phospholipid solution].

PubMed

Khaireddin, R; Hueber, A

2013-02-01

Blepharitis due to Meibom gland dysfunction (MGD) is presumed to be one of the main reasons for dry eye symptoms which occur in up to 50% of contact lens users. Thus, MGD presumably plays an important role in dry eye in contact lens wearers. In the present prospective, randomized and double blind trial the efficacy of two established treatment options for MGD and blepharitis was evaluated in symptomatic contact lens wearers. In this prospective, randomized 2-centre trial 53 symptomatic contact lens wearers suffering from blepharitis were included. Patients were randomly selected for two treatment groups: group A performed lid margin hygiene using the commonly recommended mild baby shampoo (Bübchen Kinder Shampoo-extra augenmild, Bübchen Werk Ewald Hermes Pharmazeutische Fabrik GmbH, Soest, Germany) and group B performed lid margin hygiene using a phospholipid-liposome solution specially designed for lid hygiene (Blepha Cura, Optima, Moosburg/Wang, Germany), each for 4 weeks. Before as well as 4 weeks after initiation of this study the following tests were performed: standardized subjective assessment using the ocular surface disease index, non-invasive break-up time (NIBUT) and objective evaluation of lid-parallel conjunctival folds (LIPCOF) and further lid margin criteria by double blinded evaluation of slit lamp photographs. Of the 53 symptomatic contact lens wearers suffering from blepharitis 21 (39,6%) were randomly selected for treatment group A and 32 (60.4%) for group B. In both treatment groups there was objective and subjective improvement of symptoms of dry eye in contact lens wearers. Interestingly, there was a significantly greater improvement, subjective as well as objective, in treatment group B which used the phospholipidliposome solution for lid margin hygiene compared to group A using baby shampoo. Although both therapies improved symptoms of dry eye due to blepharitis in symptomatic contact lens wearers, patients using phospholipid-liposomal solution for lid margin hygiene demonstrated a significantly greater clinical benefit from the therapy. Thus, clinical practice recommending just baby shampoo for lid margin hygiene should be re-considered, as phospholipid-liposomal solution for lid margin hygiene appears to yield greater and faster clinical benefits for symptomatic contact lens wearers suffering from dry eye symptoms.

The potential pathogenicity of chlorhexidine-sensitive Acanthamoeba strains isolated from contact lens cases from asymptomatic individuals in Tenerife, Canary Islands, Spain.

PubMed

Martín-Navarro, Carmen M; Lorenzo-Morales, Jacob; Cabrera-Serra, M Gabriela; Rancel, Fernando; Coronado-Alvarez, Nieves M; Piñero, José E; Valladares, Basilio

2008-11-01

Pathogenic strains of the genus Acanthamoeba are causative agents of a serious sight-threatening infection of the eye known as Acanthamoeba keratitis. The prevalence of this infection has risen in the past 20 years, mainly due to the increase in number of contact lens wearers. In this study, the prevalence of Acanthamoeba in a risk group constituted by asymptomatic contact lens wearers from Tenerife, Canary Islands, Spain, was evaluated. Contact lenses and contact lens cases were analysed for the presence of Acanthamoeba isolates. The isolates' genotypes were also determined after rDNA sequencing. The pathogenic potential of the isolated strains was subsequently established using previously described molecular and biochemical assays, which allowed the selection of three strains with high pathogenic potential. Furthermore, the sensitivity of these isolates against two standard drugs, ciprofloxacin and chlorhexidine, was analysed. As the three selected strains were sensitive to chlorhexidine, its activity and IC(50) were evaluated. Chlorhexidine was found to be active against these strains and the obtained IC(50) values were compared to the concentrations of this drug present in contact lens maintenance solutions. It was observed that the measured IC(50) was higher than the concentration found in these maintenance solutions. Therefore, the ineffectiveness of chlorhexidine-containing contact lens maintenance solutions against potentially pathogenic strains of Acanthamoeba is demonstrated in this study.

Bacterial adhesion forces to Ag-impregnated contact lens cases and transmission to contact lenses.

PubMed

Qu, Wenwen; Busscher, Henk J; van der Mei, Henny C; Hooymans, Johanna M M

2013-03-01

To measure adhesion forces of Pseudomonas aeruginosa, Staphylococcus aureus, and Serratia marcescens to a rigid contact lens (CL), standard polypropylene, and Ag-impregnated lens cases using atomic force microscopy and determine bacterial transmission from lens case to CL. Adhesion forces of bacterial strains to Ag-impregnated and polypropylene lens cases and a rigid CL were measured using atomic force microscopy. Adhesion forces were used to calculate Weibull distributions, from which transmission probabilities from lens case to CL were derived. Transmission probabilities were compared with actual transmission of viable bacteria from a lens case to the CL in 0.9% NaCl and in an antimicrobial lens care solution. Bacterial transmission probabilities from polypropylene lens cases based on force analysis coincided well for all strains with actual transmission in 0.9% NaCl. Bacterial adhesion forces on Ag-impregnated lens cases were much smaller than that on polypropylene and CLs, yielding a high probability of transmission. Comparison with actual bacterial transmission indicated bacterial killing due to Ag ions during colony-forming unit transmission from an Ag-impregnated lens case, especially for P. aeruginosa. Transmission of viable bacteria from Ag-impregnated lens cases could be further decreased by use of an antimicrobial lens care solution instead of 0.9% NaCl. Bacterial transmission probabilities are higher from Ag-impregnated lens cases than from polypropylene lens cases because of small adhesion forces, but this is compensated for by enhanced bacterial killing due to Ag impregnation, especially when in combination with an antimicrobial lens care solution. This calls for a balanced combination of antimicrobial lens care solutions and surface properties of a lens case and CL.

Compliance factors associated with contact lens-related dry eye.

PubMed

Ramamoorthy, Padmapriya; Nichols, Jason Jay

2014-01-01

To determine if compliance factors are associated with contact lens-related dry eye (CLDE). The data were derived from subject responses to a compliance survey administered in a cross-sectional study including 100 healthy, daily (nonovernight), experienced soft contact lens wearers (50 normal and 50 with CLDE). Classification into normal or CLDE groups was based on Contact Lens Dry Eye Questionnaire scores, tear breakup time, and 2 hours difference between total and comfortable daily lens wear hours. The compliance survey queried aspects of lens care, rub and rinse practices, lens and lens case replacement frequency, solution replacement, and sleeping with lenses. Statistical analysis of the data was performed using unpaired T tests, χ, and Fisher exact tests as applicable. The average age of all subjects was 24.8±4.4 years, and 60% were women. Overall compliance rates were low for several variables including recommended replacement of contact lenses (53%), rub and rinse practices (69% and 45%, respectively), care solution topping-off (80%), and washing hands before handling lenses (48%). However, almost no compliance factors were associated with CLDE status, with the exception of perceived ease or difficulty with lens care, which was rated as more difficult by the CLDE group (P=0.004). Overall compliance rates with contact lens care practices are very low, highlighting the need for more effective methods of patient education regarding contact lens care and compliance. However, almost no compliance factors were found to be associated with CLDE. Factors other than compliance likely play a bigger role in CLDE.

Polymeric hydrogels for novel contact lens-based ophthalmic drug delivery systems: a review.

PubMed

Xinming, Li; Yingde, Cui; Lloyd, Andrew W; Mikhalovsky, Sergey V; Sandeman, Susan R; Howel, Carol A; Liewen, Liao

2008-04-01

Only about 5% of drugs administrated by eye drops are bioavailable, and currently eye drops account for more than 90% of all ophthalmic formulations. The bioavailability of ophthalmic drugs can be improved by a soft contact lens-based ophthalmic drug delivery system. Several polymeric hydrogels have been investigated for soft contact lens-based ophthalmic drug delivery systems: (i) polymeric hydrogels for conventional contact lens to absorb and release ophthalmic drugs; (ii) polymeric hydrogels for piggyback contact lens combining with a drug plate or drug solution; (iii) surface-modified polymeric hydrogels to immobilize drugs on the surface of contact lenses; (iv) polymeric hydrogels for inclusion of drugs in a colloidal structure dispersed in the lens; (v) ion ligand-containing polymeric hydrogels; (vi) molecularly imprinted polymeric hydrogels which provide the contact lens with a high affinity and selectivity for a given drug. Polymeric hydrogels for these contact lens-based ophthalmic drug delivery systems, their advantages and drawbacks are critically analyzed in this review.

Effects of wearing a daily disposable lens on tear film: a randomised controlled trial.

PubMed

Chong, Pamela Qin Yi; Yeo, Sharon; Too, Cheah Loon; Boo, Cynthia; Tong, Louis

2016-05-01

Contact lens-induced dry eye is commonly encountered, although its extent is not well documented with daily disposable lenses. A novel type of contact lens system incorporating moisturising agent (alginic acid) has been developed. The aim of this study was to evaluate the effect of wearing daily 2-hydroxyethyl methacrylate disposable contact lenses for seven days on tear stability, conjunctival and limbal redness and dry eye symptoms. Then, we aimed to determine whether lens solutions containing alginic acid had any influence on tear parameters. This was a seven-day parallel group double-masked clinical trial of previous contact lens wearers, where participants were randomly assigned to wearing SEED 1dayPure moisture contact lenses with (n = 15) or without alginic acid (n = 15). Tear lipid layer thickness (LLT), non-invasive tear break-up time (NIBUT), conjunctival redness, corneal fluorescein staining, tear break-up time and Schirmer I readings were measured. Symptom severity and frequency were evaluated and combined using a global score from visual analogue scales. The mean age and standard deviation of the participants was 25 ± 3.8 years. There were 24 females and six males. After reintroduction of contact lens wear for one week, there was significant improvement in the global symptom score; however, this may not be clinically significant. There were small and clinically insignificant changes in limbal and conjunctival hyperaemia but no significant changes in lipid layer thickness, Schirmer I and NIBUT in overall participants. The use of alginic acid in lens solutions did not affect these parameters compared to control lenses (p > 0.05). After seven days of wearing a modern daily disposable lens, there was no significant deterioration of tear function in a group of young contact lens wearers. In this short-term study, there was no evidence of significant benefit of lens solutions containing alginic acid used with HEMA lenses. © 2016 The Authors Clinical and Experimental Optometry © 2016 Optometry Australia.

Contact lenses fitting teaching: learning improvement with monitor visualization of webcam video recordings

NASA Astrophysics Data System (ADS)

Gargallo, Ana; Arines, Justo

2014-08-01

We have adapted low cost webcams to the slit lamps objectives with the aim of improving contact lens fitting practice. With this solution we obtain good quality pictures and videos, we also recorded videos of eye examination, evaluation routines of contact lens fitting, and the final practice exam of our students. In addition, the video system increases the interactions between students because they could see what their colleagues are doing and take conscious of their mistakes, helping and correcting each others. We think that the proposed system is a low cost solution for supporting the training in contact lens fitting practice.

Castroviejo Lecture 2009: 40 years in search of the perfect contact lens.

PubMed

Cavanagh, H Dwight; Robertson, Danielle M; Petroll, W Matthew; Jester, James V

2010-10-01

To identify the pathophysiological changes produced by contact lens wear that predispose the cornea to infection and search for prospective modifiable risk factors that could reduce the incidence of this critical complication in millions of patients worldwide. Significant experimental and clinical publications are reviewed, and the results of ongoing studies are presented. Pseudomonas aeruginosa (PA) is the most common pathogen causing lens-related infectious keratitis over 3 decades. Contact lens wear can increase the risk of infection by increasing surface cell PA binding, thereby promoting invasion between broken tight junctions and initiating direct intracellular invasion mediated by lens-induced membrane lipid rafts. Prevention of upregulation of specific surface-binding receptors for PA with concomitant increase in infection risk is a zero damage game where independent interactions among lens type, mode of wear, oxygen transmissibility, polymer, and toxic effects of associated care solutions ideally should collectively produce no increased ability for PA to attach and/or to invade, thus minimizing the risk for lens-associated infections. The specific hypothesis tested is, "no increased epithelial surface damage... no increased PA binding or invasion... no increased risk for infection." Testing of this new paradigm has been performed in vitro and in animal and human clinical trials and correlated clinically with relative risk results from robust current epidemiological studies. Results to date clearly support the use of lens-related increases in PA binding (bench) as a noninvasive clinical predictor of risk for lens-related infection in subsequent large-scale population studies (bedside). Currently, results suggest that use of common commercial multipurpose lens care solutions with soft lenses may alone significantly increase infection risk by enhancing lens-related PA binding as compared with use of nonpreserved solutions (hydrogen peroxide). Clinical testing also shows that only peroxide solutions show significant disinfection capability against amoebic cysts. Further case-control studies to examine relative risk for infection by lens type and lens care solution are urgently needed. Millions of patients are dependent on contact lenses for vision worldwide; over 3 decades, lens use has increased, although risk for lens-related infection has remained stubbornly unchanged. Unfortunately, recent introduction of a new generation of hyper-oxygen transmissible lenses used with traditional multipurpose lens care solutions has not lowered overall risks for lens-related infections; however, similar lenses used with nonpreserved care solutions (peroxide) recently demonstrated no significant increases in PA binding in a 1-year clinical trial. Collectively, these findings along with the urgent need for amoebic cysticidal disinfection have led to a current recommendation to patients to use nonpreserved (hydrogen peroxide) care solutions in soft lens wear.

Compliance among soft contact lens wearers.

PubMed

Kuzman, Tomislav; Kutija, Marija Barisić; Masnec, Sanja; Jandroković, Sonja; Mrazovac, Danijela; Jurisić, Darija; Skegro, Ivan; Kalauz, Miro; Kordić, Rajko

2014-12-01

Contact lens compliance is proven to be crucial for preventing lens wear-related complications because of the interdependence of the steps in lens care regime and their influence on lens system microbial contamination. Awareness of the patients' lens handling compliance as well as correct recognition of non-compliant behaviours is the basis for creating more targeted strategies for patient education. The aim of this study was to investigate compliance among soft contact lens (SCL) wearers in different aspects of lens care handling and wearing habits. In our research 50 asymptomatic lens wearers filled out a questionnaire containing demographic data, lens type, hygiene and wearing habits, lenses and lens care system replacement schedule and self-evaluation of contact lens handling hygiene. We established criteria of compliance according to available manufacturer's recommendations, prior literature and our clinical experience. Only 2 (4%) of patients were fully compliant SCL wearers. The most common non-compliant behaviours were insufficient lens solution soaking time (62%), followed by failure to daily exchange lens case solution and showering while wearing lenses. 44% of patients reported storing lenses in saline solution. Mean lens storage case replacement was 3.6 months, with up to 78% patients replacing lens case at least once in 3 months. Average grade in self evaluating level of compliance was very good (4 +/- 0.78) (from 1-poor level of hygiene to 5-great level of hygiene). Lens wearers who reported excessive daily lens wear and more than 10 years of lens wearing experience were also found to be less compliant with other lens system care procedures. (t = -2.99, df=47, p < 0.0045 and t = -2.33, df= 48, p < 0.024, respectively). Our study indicates that almost all patients had some degree of non-compliance in lens system maintenance steps. Most common non-compliant behaviours were the ones that are crucial for maintaining lens sterility and preventing infection. Despite the low objective compliance rate, self grading was relatively high. Therefore, these results indicate the need for patient education and encouragement of better lens wearing habits and all of the lens maintenance steps at each patient visit.

Human corneal epithelial cell shedding and fluorescein staining in response to silicone hydrogel lenses and contact lens disinfecting solutions.

PubMed

Gorbet, Maud; Peterson, Rachael; McCanna, David; Woods, Craig; Jones, Lyndon; Fonn, Desmond

2014-03-01

A pilot study was conducted to evaluate human corneal epithelial cell shedding in response to wearing a silicone hydrogel contact lens/solution combination inducing corneal staining. The nature of ex vivo collected cells staining with fluorescein was also examined. A contralateral eye study was conducted in which up to eight participants were unilaterally exposed to a multipurpose contact lens solution/silicone hydrogel lens combination previously shown to induce corneal staining (renu® fresh™ and balafilcon A; test eye), with the other eye using a combination of balafilcon A soaked in a hydrogen peroxide care system (Clear Care®; control eye). Lenses were worn for 2, 4 or 6 hours. Corneal staining was graded after lens removal. The Ocular Surface Cell Collection Apparatus was used to collect cells from the cornea and the contact lens. In the test eye, maximum solution-induced corneal staining (SICS) was observed after 2 hours of lens wear (reducing significantly by 4 hours; p < 0.001). There were significantly more cells collected from the test eye after 4 hours of lens wear when compared to the control eye and the collection from the test eye after 2 hours (for both; n = 5; p < 0.001). The total cell yield at 4 hours was 813 ± 333 and 455 ± 218 for the test and control eyes, respectively (N = 5, triplicate, p = 0.003). A number of cells were observed to have taken up the fluorescein dye from the initial fluorescein instillation. Confocal microscopy of fluorescein-stained cells revealed that fluorescein was present throughout the cell cytoplasm and was retained in the cells for many hours after recovery from the corneal surface. This pilot study indicates that increased epithelial cell shedding was associated with a lens-solution combination which induces SICS. Our data provides insight into the transient nature of the SICS reaction and the nature of fluorescein staining observed in SICS.

A contact-lens-on-a-chip companion diagnostic tool for personalized medicine.

PubMed

Guan, Allan; Wang, Yi; Phillips, K Scott; Li, Zhenyu

2016-04-07

We present a novel, microfluidic platform that integrates human tears (1 μL) with commercial contact lens materials to provide personalized assessment of lens care solution performance. This device enabled the detection of significant differences in cleaning and disinfection outcomes between subjects and between biofilms vs. planktonic bacteria.

Efficacy of contact lens disinfecting solutions against Staphylococcus aureus and Pseudomonas aeruginosa.

PubMed

Manuj, Kapur; Gunderson, Charlise; Troupe, John; Huber, Mary E

2006-07-01

To evaluate the disinfection properties of multipurpose contact lens disinfection solutions, based on the International Organization for Standardization (ISO) 14729 guidelines. ReNu with MoistureLoc Multi-Purpose Solution, OPTI-FREE Express with Aldox Multi-Purpose Solution, Betadine 5% sterile ophthalmic preparation solution (povidone iodine), and 0.9% normal saline solution were inoculated with strains of Staphylococcus aureus and Pseudomonas aeruginosa. Surviving bacteria were quantified at specified times. ReNu with MoistureLoc, OPTI-FREE Express, and 5% ophthalmic povidone iodine were effective in achieving a 5-log reduction in bacterial count. Additionally, all three products maintained their effectivity at 72 hours. However, ReNu with MoistureLoc and povidone iodine resulted in the greatest reduction in bacterial colonization. ReNu with MoistureLoc, OPTI-FREE Express, and 5% ophthalmic povidone iodine meet the ISO 14729 guidelines for standalone contact lens solutions. However, ReNu with MoistureLoc and 5% ophthalmic povidone iodine are most efficient in reducing and maintaining low bacterial count for a period of 72 hours.

Pseudomonas aeruginosa Survival at Posterior Contact Lens Surfaces after Daily Wear

PubMed Central

Wu, Yvonne T.; Zhu, Lucia S.; Tam, K. P. Connie; Evans, David J.; Fleiszig, Suzanne M. J.

2015-01-01

Purpose Pseudomonas aeruginosa keratitis is a sight-threatening complication of contact lens wear, yet mechanisms by which lenses predispose to infection remain unclear. Here, we tested the hypothesis that tear fluid at the posterior contact lens surface can lose antimicrobial activity over time during lens wear. Methods Daily disposable lenses were worn for 1, 2, 4, 6 or 8 h immediately after removal from their packaging, or after presoaking in sterile saline for 2 days to remove packaging solution. Unworn lenses were also tested, some coated in tears “aged” in vitro for 1 or 8 h. Lenses were placed anterior surface down into tryptic soy agar cradles containing gentamicin (100µg/ml) to kill bacteria already on the lens, and posterior surfaces inoculated with gentamicin-resistant P. aeruginosa for 3 h. Surviving bacteria were enumerated by viable counts of lens homogenates. Results Posterior surfaces of lenses worn by patients for 8 h supported more P. aeruginosa growth than lenses worn for only 1 h, if lenses were presoaked prior to wear (~ 2.4-fold, p = 0.01). This increase was offset if lenses were not presoaked to remove packaging solution (p = 0.04 at 2 h and 4 h). Irrespective of presoaking, lenses worn for 8 h showed more growth on their posterior surface than unworn lenses coated with tear fluid that was “aged” for 8 h vitro (~8.6-fold, presoaked, p = 0.003: ~ 5.4-fold from packaging solution, p = 0.004). Indeed, in vitro incubation did not impact tear antimicrobial activity. Conclusions This study shows that post lens tear fluid can lose antimicrobial activity over time during contact lens wear, supporting the idea that efficient tear exchange under a lens is critical for homeostasis. Additional studies are needed to determine applicability to other lens types, wearing modalities, and relevance to contact lens-related infections. PMID:25955639

Effect of lens care system on silicone hydrogel contact lens wettability.

PubMed

Guillon, Michel; Maissa, Cécile; Wong, Stéphanie; Patel, Trisha; Garofalo, Renée

2015-12-01

The purpose was to compare the effect of the repeated usage of two care systems (one hydrogen peroxide cleaning and disinfecting system and one polyaminopropyl biguanide (PHMB) containing multi-purpose system) with silicone hydrogel contact lenses worn for three months on a daily wear modality. A specific aspect of interest was of the effect of the care systems on contact lens wettability. Seventy-four symptomatic contact lens wearers, habitually wearing either ACUVUE(®) OASYS(®) (n=37) or PureVision™ (n=37), constituted the study population. The study was a two-arm prospective, investigator-masked, bilateral study of three-month duration to evaluate the effects of CLEAR CARE(®) compared with renu(®) fresh™. The subjects were randomized to one of the two lens care systems. Contact lens wettability and surface cleanliness were assessed with the Tearscope and reported in terms of pre-lens non-invasive break-up time (PL-NIBUT) and visible deposits. Baseline assessments at enrollment were with the subjects' own contact lenses worn for at least 6h when using their habitual PHMB-preserved care system and at the dispensing visit with new contact lenses. At the follow-up visits, the contact lenses were worn for at least 6h, and were at least 11 days old for ACUVUE(®) OASYS(®) and 25 days old for PureVision™. The results obtained showed that: (i) with CLEAR CARE(®), a significant improvement in contact lens wettability was recorded compared with the habitual care system at the three-month follow-up visit (mean median PL-NIBUT 5.8 vs. 4.0 s, p<0.001). Further, with this same lens care system a significant increase in wettability was observed at the three-month follow-up visit compared with dispensing (mean median PL-NIBUT 5.8 vs. 4.5s, p=0.022). (ii) Whereas no difference in contact lens wettability was observed at dispensing between the two lens care groups (mean PL-NIBUT: 4.5 vs. 4.2s, p=0.518), a significantly more stable pre-lens tear film was observed with CLEAR CARE(®) than with renu(®) fresh™ at both the two-month (mean PL-NIBUT: 4.6 vs. 3.7s, p=0.005) and three-month (mean PL-NIBUT: 5.8 vs. 4.2 s, p=0.028) visits. iii. With renu(®) fresh™, no significant differences were observed at the end of three months of use compared with either the habitual care system or the new contact lens solution (mean PL-NIBUT: 3M 4.2 vs. Disp 4.2 s (p=0.420) vs. enrolment habitual care solution 5.1s (p=0.734)). iv. With CLEAR CARE(®) significant increases in the incidence of surfaces free of both mucus (3 month 95%. vs. habitual solution 82% enrolment; p=0.005) and lipid (3 month 87% vs. habitual solution 72% enrolment; p=0.009) were observed. Significantly better contact lens wettability and surface cleanliness were achieved for ACUVUE(®) OASYS(®) and PureVision™ with CLEAR CARE(®) than with renu(®) fresh™ at the end of three months of use. Copyright © 2015. Published by Elsevier Ltd.

Resistance of Pseudomonas aeruginosa isolates to hydrogel contact lens disinfection correlates with cytotoxic activity.

PubMed

Lakkis, C; Fleiszig, S M

2001-04-01

One of the most common pathogens in infection of hydrogel contact lens wearers is Pseudomonas aeruginosa, which can gain access to the eye via contamination of the lens, lens case, and lens care solutions. Only one strain per species is used in current regulatory testing for the marketing of chemical contact lens disinfectants. The aim of this study was to determine whether P. aeruginosa strains vary in their susceptibility to hydrogel contact lens disinfectants. A method for rapidly screening bacterial susceptibility to contact lens disinfectants was developed, based on measurement of the MIC. The susceptibility of 35 P. aeruginosa isolates to two chemical disinfectants was found to vary among strains. MICs ranged from 6.25 to 100% for both disinfectants at 37 degrees C, and a number of strains were not inhibited by a 100% disinfectant concentration in the lens case environment at room temperature (22 degrees C). Resistance to disinfection appeared to be an inherent rather than acquired trait, since some resistant strains had been isolated prior to the introduction of the disinfectants and some susceptible P. aeruginosa strains could not be made more resistant by repeated disinfectant exposure. A number of P. aeruginosa strains which were comparatively more resistant to short-term disinfectant exposure also demonstrated the ability to grow to levels above the initial inoculum in one chemical disinfectant after long-term (24 to 48 h) disinfectant exposure. Resistance was correlated with acute cytotoxic activity toward corneal epithelial cells and with exsA, which encodes a protein that regulates cytotoxicity via a complex type III secretion system. These results suggest that chemical disinfection solutions may select for contamination with cytotoxic strains. Further investigation of the mechanisms and factors responsible for resistance may also lead to strategies for reducing adverse responses to contact lens wear.

Military aviation: a contact lens review.

PubMed

Lattimore, M R

1990-10-01

The military aviation communities have benefitted from the development of advanced electro-optical avionics systems. One drawback that has emerged is an increasing system incompatibility with traditional spectacle visual corrections. An alternative solution to the refractive error correction problem that some services have been investigating is that of contact lens wear. Since this much-debated topic is currently of command interest, a general overview of contact lens issues is presented as a framework for future discussions.

The Correlation between Daily Lens Wear Duration and Dry Eye Syndrome.

PubMed

Lubis, Rodiah Rahmawaty; Gultom, Monica Tumiar Hanna

2018-05-20

To analyze the correlation between the daily lens wear duration and dry eye syndrome. This study was an analytic cross sectional study using consecutive sampling conducted among the students in Economy and Bussiness Faculty and Faculty of Humanities in University of Sumatera Utara aged between 17 to 23 that wore contact lens continously for at least a year and 5 days a week. The symptoms were assessed using Contact Lens Dry Eye Questionnaire-8 (CLDEQ-8) and interview about their contact lens comfort; eye drops usage, contact lens washing habit, daily circumstances, places to buy contact lens and personal experince in wearing contact lens. The questionnaire was completed by 53 students. All of them were female and wore softlens wearers. The mean duration of daily wear was 8.19 ± 2.20 hours. The most common symptom experienced was dry eye and the least symptom experienced was removing lens. The most frequent symptom experienced was closing eyes and the least frequent symptom experienced was removing lenses. This study used Exact Test as analysis statistic method. The result was p > 0.05 which means there is no correlation between daily lens wear duration and dry eye syndrome. This study showed that dry eye syndrome was not correlated with daily lens wear duration, but affected by many factors such as contact lens, lens care solution, eye drops usage and environment.

Acidification of rabbit corneal endothelium during contact lens wear in vitro.

PubMed

Giasson, C; Bonanno, J A

1995-04-01

Contact lens wear causes significant epithelial and stromal acidosis. In this study, we tested whether lens wear can cause endothelial acidosis as well. Rabbit corneas were isolated and perfused in vitro. The endothelial intracellular pH (pHi) was measured with a pH sensitive fluorescent probe (BCECF). Three conditions were examined: 1) Polymethylmethacrylate (PMMA) and rigid gas-permeable (RGP) contact lens wear using a range of oxygen transmissibility (Dk/L) from 0 to 121, 2) epithelial hypoxia produced by exposure to oligomycin/sodium azide solution or epithelial perfusion with 100% N2 equilibrated Ringer's solution, and 3) epithelial exposure to Ringer's equilibrated with 5% CO2, balance air. PMMA and RGP contact lens wear acidified endothelial cells by 0.23 +/- 0.01 (n = 23) and 0.11 +/- 0.01 pH units (n = 23), respectively, within twenty min of lens insertion. Epithelial hypoxia, induced by sodium azide and oligomycin, reversibly acidified the endothelium by 0.04 +/- 0.01 pH units (n = 4). However, epithelial hypoxia induced by perfusion with 100% N2 equilibrated Ringer's did not have a significant effect on endothelial pHi. Introduction of 5% CO2 to the epithelium, acidified the endothelium by 0.15 +/- 0.02 pH units (n = 7) within 10 min. We conclude that contact lens wear can significantly acidify corneal endothelial cells. The endothelial pHi change is caused almost exclusively by a build up of CO2 behind the lens; hypoxia having very little contribution. As expected, RGP contact lenses induced less endothelial acidosis than PMMA controls.

Short-Term Deposition of PM2.5 Particles on Contact Lens Surfaces: Effect on Oxygen Permeability and Refractive Index.

PubMed

Dong, Zhizhang; Ding, Xiaoyan; Li, Yong; Gan, Yifeng; Wang, Yanhui; Xu, Libin; Wang, Yahong; Zhou, Ying; Li, Juan

2018-05-22

To identify the deposition of fine (≤2.5 μm diameter) particulate matter (PM) particles (PM 2.5 ) on contact lens surfaces and to investigate the effects of such deposition on the oxygen permeability (OP) and refractive index (RI) of contact lenses. A total of 36 contact lenses, including rigid gas permeable (RGP) lens and soft contact lens (SCL), were investigated. RGP lens (n=12) and SCL (n=12) (experimental group) were incubated in a PM 2.5 solution for 24 h, after which PM 2.5 -treated RGP lens (n=6) and SCL (n=6) were further washed for 1 h in phosphate-buffered saline (PBS). All lenses were examined by field emission scanning electron microscopy. OP and RI of all lenses were measured. Average-sized PM 2.5 particles deposited on RGP contact lens and SCL surfaces after immersion in the PM 2.5 solution were 3.192 ± 1.637 and 2.158 ± 1.187/100 μm 2 , respectively. On RGP lens surfaces, we observed both large (≥2.5 µm diameter) and small (PM 2.5 ) particles. PM 2.5 particles were deposited in diffuse patterns, primarily along the honeycomb structural border of SCL, while no PM 2.5 particles were found in the honeycomb hole of SCL surfaces. Washing in PBS removed the larger PM particles from RGP lens surfaces, but left copious amounts of PM 2.5 particles. In contrast, nearly all PM particles were removed from SCL surfaces after PBS washing. OP values of RGP lens and SCL appeared to be unchanged by PM 2.5 deposition. RI values increased in both RGP lens and SCL groups after PM 2.5 deposition. However, these increases were not statistically significant, suggesting that PM 2.5 deposition itself does not cause fluctuations in contact lens RI. Deposition of PM 2.5 particles on contact lens surfaces varies according to lens material. PM 2.5 particles deposited on SCL, but only large particles on RGP surfaces were able to be removed by washing in PBS and did not appear to alter OP and RI of either lens type.

Contact lens physical properties and lipid deposition in a novel characterized artificial tear solution

PubMed Central

Heynen, Miriam; Kay, Lise M.M.; Dominici, Claudia Yvette; Khan, Warda; Ng, Wendy W.S.; Jones, Lyndon

2011-01-01

Purpose To characterize various properties of a physiologically-relevant artificial tear solution (ATS) containing a range of tear film components within a complex salt solution, and to measure contact lens parameters and lipid deposition of a variety of contact lens materials after incubation in this ATS. Methods A complex ATS was developed that contains a range of salts, proteins, lipids, mucin, and other tear film constituents in tear-film relevant concentrations. This ATS was tested to confirm that its pH, osmolality, surface tension, and homogeneity are similar to human tears and remain so throughout the material incubation process, for up to 4 weeks. To confirm that silicone hydrogel and conventional hydrogel contact lens materials do not alter in physical characteristics beyond what is allowed by the International Organization for Standardization (ISO) 18369–2. The diameter, center thickness, and calculated base curve were measured for five different lens materials directly out of the blister pack, after a rinse in saline and then following a two week incubation in the modified ATS. To test the ATS and the effect of its composition on lipid deposition, two lens materials were incubated in the ATS and a modified version for several time points. Both ATS solutions contained trace amounts of carbon-14 cholesterol and phosphatidylcholine, such that deposition of these specific lipids could be quantified using standard methods. Results This ATS is a complex mixture that remains stable at physiologically relevant pH (7.3–7.6), osmolality (304–306 mmol/kg), surface tension (40–46 dynes/cm) and homogeneity over an incubation period of three weeks or more. The physical parameters of the lenses tested showed no changes beyond that allowed by the ISO guidelines. Incubations with the ATS found that balafilcon A lenses deposit significantly more cholesterol and phosphatidylcholine than omafilcon A lenses (p<0.05) and that removing lactoferrin and immunoglobulin G from the ATS can significantly decrease the mass of lipid deposited. Conclusions This paper describes a novel complex artificial tear solution specially designed for in-vial incubation of contact lens materials. This solution was stable and did not adversely affect the physical parameters of the soft contact lenses incubated within it and showed that lipid deposition was responsive to changes in ATS composition. PMID:22219635

IMPACT OF A RINSE STEP ON PROTEIN REMOVAL FROM SILICONE HYDROGEL CONTACT LENSES

PubMed Central

Pucker, Andrew D.; Nichols, Jason J.

2010-01-01

PURPOSE To determine the impact of the rinse step in “no rub” contact lens care systems relative to its ability to assist in removing loosely associated and bound tear film proteins from a worn silicone hydrogel lens. METHODS After informed consent, subjects were fitted with lotrafilcon B contact lenses (CIBA Vision, Inc). If the fit was acceptable, subjects were asked to wear the lenses on a daily wear basis for 5 (+2, −0) days for an outcome visit. Subjects were instructed to use AQuify Multi-Purpose Disinfecting Solution (CIBA Vision, Inc) following the manufacturer's “no rub” instructions. At the outcome visit, contact lenses were then collected by a gloved examiner, with a sterile metal forceps, who rinsed the right lens but did not rinse the left lens upon removal from the eyes. Protein was extracted with a 50:50 0.2% trifluoroacetic acid-acetonitrile solution and quantified using a Bradford analyses. RESULTS Twenty contact lens wearers were enrolled in this study. For the non-rinsed lenses, the first extraction yielded 13.4 ± 9.2 µg/lens of protein, while the second extraction yielded 5.8 ± 2.8 µg/lens of protein. For the rinsed lenses, first extraction yielded an average of 3.0 ± 1.9 µg/lens of protein, while the second extraction yielded an average of 4.0 ± 2.3 µg/lens. Repeated measures ANOVA showed a significant interaction (F-statistic = 18.9, p< 0.0001) between the rinse of a lens and extraction number. CONCLUSIONS Rinsing a contact lens following removal from the eye removes well over one-half of the protein associated with it. Further, in order to biochemically recover all protein from a silicone hydrogel lens, it may be important to perform more than one chemical extraction from it. PMID:19609231

Material properties that predict preservative uptake for silicone hydrogel contact lenses.

PubMed

Green, J Angelo; Phillips, K Scott; Hitchins, Victoria M; Lucas, Anne D; Shoff, Megan E; Hutter, Joseph C; Rorer, Eva M; Eydelman, Malvina B

2012-11-01

To assess material properties that affect preservative uptake by silicone hydrogel lenses. We evaluated the water content (using differential scanning calorimetry), effective pore size (using probe penetration), and preservative uptake (using high-performance liquid chromatography with spectrophotometric detection) of silicone and conventional hydrogel soft contact lenses. Lenses grouped similarly based on freezable water content as they did based on total water content. Evaluation of the effective pore size highlighted potential differences between the surface-treated and non-surface-treated materials. The water content of the lens materials and ionic charge are associated with the degree of preservative uptake. The current grouping system for testing contact lens-solution interactions separates all silicone hydrogels from conventional hydrogel contact lenses. However, not all silicone hydrogel lenses interact similarly with the same contact lens solution. Based upon the results of our research, we propose that the same material characteristics used to group conventional hydrogel lenses, water content and ionic charge, can also be used to predict uptake of hydrophilic preservatives for silicone hydrogel lenses. In addition, the hydrophobicity of silicone hydrogel contact lenses, although not investigated here, is a unique contact lens material property that should be evaluated for the uptake of relatively hydrophobic preservatives and tear components.

Removal of biofilm from contact lens storage cases.

PubMed

Wu, Yvonne T; Zhu, Hua; Willcox, Mark; Stapleton, Fiona

2010-12-01

Lens case hygiene practices are important in maintaining safe contact lens wear. However, the effectiveness of various lens case cleaning practices have not been evaluated and compared. This in vitro study aimed to evaluate and compare the efficacy of cleaning practices that are most commonly carried out by lens wearers and recommended by practitioners. Pseudomonas aeruginosa 122, Serratia marcescens ATCC 13880, and Staphylococcus aureus ATCC 6538 were the challenge bacteria for biofilm formation on unused lens cases from two different manufacturers. After establishment of the biofilm, each lens case was subjected to one of the six cleaning regimens: "rinsed," "rubbed and rinsed," "air-dried," "soaked in a multipurpose contact lens solution," "tissue-wiped," and "lids recapped." The level of residual biofilm was quantified at the end of each cleaning regimen. The efficacy of each cleaning regimen was then compared. Mechanical rubbing and wiping of lens cases were the most effective cleaning regimen tested in reducing biofilm. Soaking lenses in disinfecting solution for 6 hours removed the majority of biofilm from lens cases. Rinsing lens cases alone provided only minimal efficacy in reducing biofilm. Air-drying or recapping the cases with the lid without any other additional cleaning methods were the least efficient at removing biofilm. Based on this study, digital rubbing and rinsing and/or wiping the lens cases with tissue is recommended. Air-drying or recapping the lens case lids after use without any additional cleaning methods should be discouraged with non-antimicrobial lens cases.

Resistance of Pseudomonas aeruginosa Isolates to Hydrogel Contact Lens Disinfection Correlates with Cytotoxic Activity

PubMed Central

Lakkis, Carol; Fleiszig, Suzanne M. J.

2001-01-01

One of the most common pathogens in infection of hydrogel contact lens wearers is Pseudomonas aeruginosa, which can gain access to the eye via contamination of the lens, lens case, and lens care solutions. Only one strain per species is used in current regulatory testing for the marketing of chemical contact lens disinfectants. The aim of this study was to determine whether P. aeruginosa strains vary in their susceptibility to hydrogel contact lens disinfectants. A method for rapidly screening bacterial susceptibility to contact lens disinfectants was developed, based on measurement of the MIC. The susceptibility of 35 P. aeruginosa isolates to two chemical disinfectants was found to vary among strains. MICs ranged from 6.25 to 100% for both disinfectants at 37°C, and a number of strains were not inhibited by a 100% disinfectant concentration in the lens case environment at room temperature (22°C). Resistance to disinfection appeared to be an inherent rather than acquired trait, since some resistant strains had been isolated prior to the introduction of the disinfectants and some susceptible P. aeruginosa strains could not be made more resistant by repeated disinfectant exposure. A number of P. aeruginosa strains which were comparatively more resistant to short-term disinfectant exposure also demonstrated the ability to grow to levels above the initial inoculum in one chemical disinfectant after long-term (24 to 48 h) disinfectant exposure. Resistance was correlated with acute cytotoxic activity toward corneal epithelial cells and with exsA, which encodes a protein that regulates cytotoxicity via a complex type III secretion system. These results suggest that chemical disinfection solutions may select for contamination with cytotoxic strains. Further investigation of the mechanisms and factors responsible for resistance may also lead to strategies for reducing adverse responses to contact lens wear. PMID:11283074

Detachment of trophozoites of Acanthamoeba species from soft contact lenses with BEN22 detergent, BioSoak, and Renu multi-purpose solutions.

PubMed

Raali, E; Vaahtoranta-Lehtonen, H H; Lehtonen, O P

2001-07-01

BEN22 detergent was studied for its ability to detach Acanthamoeba from soft contact lenses without mechanical cleaning or separate cleaning agents. Trophozoites of Acanthamoeba castellanii and A. polyphaga were adhered onto nonionic, high water content soft contact lenses. The lenses were immersed for 2 hours in contact lens care solutions and the remaining trophozoites were counted microscopically. The counts were compared to the counts on the same lens before treatment. BEN22 (50:50 mixture of L-alpha-L-rhamnopyranosyl-beta-hydroxydecanoyl-beta-hydroxydecanoate and 2-O-alpha-L-rhamnopyranosyl-alpha-L-rhamnopyranosyl-beta-hydroxydecanoyl-beta-hydroxydecanoate) (Kassell Industries, Inc., Wisconsin Dells, WI) in a concentration of 0.05% detached the trophozoites to a statistically significant greater extent than saline, but commercial ReNu Multi-Purpose Solution (Bausch & Lomb, Italy) and BioSoak (Finnsusp Ltd., Finland) did so as well. ReNu Multi-Purpose Solution was more effective than 0.005% BEN22 in detaching the trophozoites of both of the Acanthamoeba strains. After the 2 hour immersion period, a maximum of 97% of the initial trophozoites were detached. The variation between individual lenses was significantly greater than that within the different areas of one lens. BEN22 had no reliable detaching effect on Acanthamoeba. The variation between lenses was great, and the rate of detachment was low with all the agents tested indicating that immersion and rinsing in the solutions tested cannot be considered as a safe substitute for proper disinfection against Acanthamoeba in contact lens care.

In vitro release of two anti-muscarinic drugs from soft contact lenses

PubMed Central

Hui, Alex; Bajgrowicz-Cieslak, Magdalena; Phan, Chau-Minh; Jones, Lyndon

2017-01-01

The purpose of this study was to investigate the release of the anti-myopia drugs atropine sulfate and pirenzepine dihydrochloride from commercially available soft contact lenses. Standard ultraviolet (UV) absorbance–concentration curves were generated for atropine and pirenzepine. Ten commercially available contact lenses, including four multifocal lenses, were loaded by soaking in atropine or pirenzepine solutions at two different concentrations (10 mg/mL and 1 mg/mL). The release of the drugs into phosphate-buffered saline was determined over the course of 24 hours at 34°C using UV absorbance. Materials with surface charge released the greatest amount of atropine when loaded with either concentration when compared to the other lens types (p<0.05), releasing upward of 1.026±0.035 mg/lens and 0.979±0.024 mg/lens from etafilcon A and ocufilcon A, respectively. There were no significant differences in the amount of atropine or pirenzepine released from the multifocal and non-multifocal lenses made from the same lens materials. Narafilcon A material demonstrated prolonged release of up to 8 hours when loaded with pirenzepine, although the overall dose delivered from the lens into the solution was among the lowest of the materials investigated. The rest of the lenses reached a plateau within 2 hours of release, suggesting that they were unable to sustain drug release into the solution for long periods of time. Given that no single method of myopia control has yet shown itself to be completely effective in preventing myopia progression, a combination of optical and pharmaceutical devices comprising a drug delivering contact lens presents a novel solution that warrants further investigation. PMID:29213204

Acanthamoeba keratitis in Scotland: risk factors for contact lens wearers.

PubMed

Seal, D V; Kirkness, C M; Bennett, H G; Peterson, M

1999-01-01

To investigate risk factors for Acanthamoeba keratitis amongst contact lens wearers in Scotland. Patients with Acanthamoeba keratitis in the Scottish study, all of whom wore contact lenses, were compared with 46 healthy asymptomatic contact lens-wearing controls. They were all visited at home for contact lens and environmental microbiological sampling. In addition, all 288 optical practices in the West of Scotland were polled for contact lens types and disinfecting solutions sold in 1995, and a sample, each of whom fitted more than 500 contact lenses per year, were polled for a second time. Independently, a poll was commissioned by the Eyecare Information Service in July/August 1995 to estimate the numbers of contact lens wearers in Scotland and the UK. Industry was polled for numbers of each contact lens disinfecting regimen sold in Scotland in 1995. West of Scotland, UK. All contact lens wearers among the 3 million population of the West of Scotland Health Board Areas. Risk factors for Acanthamoeba infection and recommendations for its prevention. When Acanthamoeba infection occurred, patients' home water systems were frequently (54%) found to be colonised by this amoeba. Patients more frequently washed their storage cases in tap water than controls (P<0.05) with resulting contamination, kept storage cases wet rather than air drying them (P<0.05), and had coliform bacteria cultured from the storage case (P<0.05) and had viable Acanthamoeba within the storage case (P<0.0001). Overall, patients were found to have significantly more risk factors than controls (P<0.0001). The noncompliant use of chlorine tablet disinfection, or failure to disinfect contact lenses at all, was associated with increased risk (P<0.05). Ionic high water content contact lenses (FDA group 4 material), when used without disinfection or with non-compliant use of low chlorine (Soflab) tablet-based disinfection, were associated with increased risk of Acanthamoeba infection (P<0.05). In log-linear modelling of risky hygiene behaviours associated with contamination of storage cases with Acanthamoeba, the most significant behaviour was found to be use of the less effective disinfection methods (chlorine tablets or no disinfection). However further investigation showed that these methods were associated with an increased probability of rinsing the storage case in tap water, so that these two behaviours are confounded in the group studied. Failure to disinfect contact lenses, non-compliant use of chlorine tablets and/or introduction of tap water rinsing of storage cases were associated with increased risk of Acanthamoeba infection. New multipurpose solutions and hydrogen peroxide gave the lowest risk of Acanthamoeba infection, with no statistically significant difference between them. Ionic high-water content (FDA group 4) contact lenses were at increased risk of being associated with Acanthamoeba keratitis if used without effective disinfection (multipurpose solutions or hydrogen peroxide). The use of domestic tap water for contact lens and storage case hygiene must be avoided, as a chain-of-causation' was identified from the home water supply.

In Vitro Spoilation of Silicone-Hydrogel Soft Contact Lenses in a Model-Blink Cell.

PubMed

Peng, Cheng-Chun; Fajardo, Neil P; Razunguzwa, Trust; Radke, Clayton J

2015-07-01

We developed an in vitro model-blink cell that reproduces the mechanism of in vivo fouling of soft contact lenses. In the model-blink cell, model tear lipid directly contacts the lens surface after forced aqueous rupture, mirroring the pre-lens tear-film breakup during interblink. Soft contact lenses are attached to a Teflon holder and immersed in artificial tear solution with protein, salts, and mucins. Artificial tear-lipid solution is spread over the air/tear interface as a duplex lipid layer. The aqueous tear film is periodically ruptured and reformed by withdrawing and reinjecting tear solution into the cell, mimicking the blink-rupture process. Fouled deposits appear on the lenses after cycling, and their compositions and spatial distributions are subsequently analyzed by optical microscopy, laser ablation electrospray ionization mass spectrometry, and two-photon fluorescence confocal scanning laser microscopy. Discrete deposit (white) spots with an average size of 20 to 300 μm are observed on the studied lenses, confirming what is seen in vivo and validating the in vitro model-blink cell. Targeted lipids (cholesterol) and proteins (albumin from bovine serum) are identified in the discrete surface deposits. Both lipid and protein occur simultaneously in the surface deposits and overlap with the white spots observed by optical microscopy. Additionally, lipid and protein penetrate into the bulk of tested silicone-hydrogel lenses, likely attributed to the bicontinuous microstructure of oleophilic silicone and hydrophilic polymer phases of the lens. In vitro spoilation of soft contact lenses is successfully achieved by the model-blink cell confirming the tear rupture/deposition mechanism of lens fouling. The model-blink cell provides a reliable laboratory tool for screening new antifouling lens materials, surface coatings, and care solutions.

Lens material and formulation of multipurpose solutions affects contact lens disinfection.

PubMed

Santos, Lívia; Oliveira, Rosário; Oliveira, M Elisabete C D Real; Azeredo, Joana

2011-08-01

To assess the disinfection efficacy of multipurpose solutions (MPS) against different bacterial species adhered either to silicon hydrogel or to conventional hydrogel contact lenses (CLs). The influences of the MPS formulation and the chemical composition of the lens material were investigated. This investigation followed the standard 14729, which establishes the guidelines for assessing CL disinfecting solutions. Two commercially available (Opti-Free(®) Express(®) and Renu(®) Multiplus) solutions and one recalled solution (Complete(®) MoisturePlus™) were used in this study. After disinfection, the number of survivors was estimated by the colony forming units' method. The lens material appears to influence disinfection. The conventional hydrogel polymacon exhibited the highest disinfection scores, a fact that should be related with the lack of electrostatic attraction towards the biocides and its hydrophilicity. The MPS formulation appears to have influence in disinfection efficacy as well. For most adhered bacteria, Opti-Free(®) was capable of reducing cell concentration in 4-log. Disinfection results from multivariate factors and this study confirmed that the lens material and the MPS play a very important role in the disinfection efficacy of CL. Copyright © 2011. Published by Elsevier Ltd.

Solutions for care of silicone hydrogel lenses.

PubMed

Willcox, Mark D P

2013-01-01

During wear of contact lenses on a daily wear basis, it is necessary to disinfect the lens overnight before reinserting the lens the next day. The ability of the solutions used for this to disinfect lenses and lens cases is important for safe lens wear. The literature on the disinfecting ability of multipurpose disinfecting solutions (MPDS) commonly used with silicone hydrogel lenses reported during the period 2000 to 2012 is reviewed, as this is the period of time during which these lenses have been commercially available. Particular emphasis is placed on the ability of disinfecting solutions to control colonization of lens cases by microbes and changes in composition and use of the solutions. In addition, the literature is reviewed on ways of minimizing lens case microbial contamination. Maintaining the hygiene of contact lenses and lens cases is important in minimizing various forms of corneal infiltrative events that occur during lens wear. Although lens case contamination is not associated with different lenses, it is determined by use of different MPDS. MPDS that allow more frequent or heavy contamination of cases by Gram-negative bacteria are associated with a higher incidence of corneal infiltrative events. MPDS are now available that contain dual disinfectants. Wiping lens cases with tissues or using lens cases that incorporate silver are associated with reductions in contamination in clinical trials. Similarly, using MPDS to rub and rinse lenses before disinfection may reduce levels of microbes on lenses. The MPDS also contain surfactants that help reduce deposition and denaturation of proteins on lenses. Improvements in MPDS formulations and hygiene practices may help to reduce the incidence of adverse events that are seen during use with silicone hydrogel lenses.

AFM and SFG studies of pHEMA-based hydrogel contact lens surfaces in saline solution: adhesion, friction, and the presence of non-crosslinked polymer chains at the surface.

PubMed

Kim, Seong Han; Opdahl, Aric; Marmo, Chris; Somorjai, Gabor A

2002-04-01

The surfaces of two types of soft contact lenses neutral and ionic hydrogels--were characterized by atomic force microscopy (AFM) and sum-frequency-generation (SFG) vibrational spectroscopy. AFM measurements in saline solution showed that the presence of ionic functional groups at the surface lowered the friction and adhesion to a hydrophobic polystyrene tip. This was attributed to the specific interactions of water and the molecular orientation of hydrogel chains at the surface. Friction and adhesion behavior also revealed the presence of domains of non-crosslinked polymer chains at the lens surface. SFG showed that the lens surface became partially dehydrated upon exposure to air. On this partially dehydrated lens surface, the non-crosslinked domains exhibited low friction and adhesion in AFM. Fully hydrated in saline solution, the non-crosslinked domains extended more than tens of nanometers into solution and were mobile.

Acanthamoeba Keratitis among Rigid Gas Permeable Contact Lens Wearers in the United States, 2005 through 2011.

PubMed

Cope, Jennifer R; Collier, Sarah A; Schein, Oliver D; Brown, Allison C; Verani, Jennifer R; Gallen, Rachel; Beach, Michael J; Yoder, Jonathan S

2016-07-01

To describe the clinical presentation and outcomes of Acanthamoeba keratitis (AK) in rigid gas permeable (RGP) contact lens wearers and to identify modifiable risk factors. Case-control investigation. Patients were RGP contact lens-wearing United States residents with a diagnosis of AK from 2005 through 2011. Controls were RGP contact lens wearers with no history of AK who were at least 12 years of age. Patients were identified during 2 multistate AK outbreak investigations. Controls from the first investigation in 2007 were identified using a reverse address directory. In the second investigation, controls were recruited from participating ophthalmology and optometry practices. Patients and controls were interviewed by phone using a standardized questionnaire. Odds ratios (ORs) and Fisher exact P values were calculated to assess risk factors associated with infection. Acanthamoeba keratitis, a rare eye disease primarily affecting contact lens wearers, is caused by free-living amebae, Acanthamoeba species. We identified 37 patients in the 2 investigations, 10 (27%) from the 2007 investigation and 27 (73%) from 2011. There were 17 healthy controls, 9 (53%) from 2007 and 8 (47%) from 2011. Among patients, 9 (24%) wore RGP lenses for orthokeratology or therapeutic indication; no controls wore RGP lenses for these indications. Significant risk factors for AK were wearing lenses for orthokeratology (OR, undefined; P = 0.02), sleeping while wearing lenses (OR, 8.00; P = 0.04), storing lenses in tap water (OR, 16.00; P = 0.001), and topping off contact lens solution in the case (OR, 4.80; P = 0.01). After stratifying by use of RGP lenses for orthokeratology, storing lenses in tap water and topping off remained significant exposures. Nearly one quarter of patients were orthokeratology wearers. Using tap water to store RGP lenses and topping off solution in the lens case were modifiable risk behaviors identified in RGP wearers who wore lenses for both orthokeratology and nonorthokeratology indications. Rigid gas permeable wearers should avoid exposing their lenses to tap water and should empty their cases and use fresh lens solution each time they take out their lenses. Published by Elsevier Inc.

The effect of compliance on contact lens case contamination.

PubMed

Tilia, Daniel; Lazon de la Jara, Percy; Zhu, Hua; Naduvilath, Thomas J; Holden, Brien A

2014-03-01

To determine the efficacy of written instructions on contact lens case hygiene and to quantify the effect of noncompliance on contact lens case contamination. Data were retrospectively analyzed from 16 prospective, 3-month daily-wear studies during which six commercially available silicone hydrogel contact lenses and seven lens care solutions (LCS) were tested following a similar protocol. Verbal instructions regarding case hygiene (rinse case with LCS, not tap water) were given in nine studies, while the same instructions were given verbally and in written format in seven studies. A survey on contact lens, LCS, and lens case hygiene was completed at 1- and 3-month visits and compliance with case hygiene instructions was determined. Regular contact lens cases were used for 1 month and collected for microbial analysis at the 1- and 3-month visits. The rate of case contamination and the types of microbes contaminating cases were evaluated. Participants given verbal and written instructions were more likely to be compliant with case hygiene instructions than those just given verbal instructions (odds ratio [OR]: 2.19, p < 0.001, 95% confidence interval [CI]: 1.40-3.44). The overall case contamination rate was 79%. Use of tap water to rinse contact lens cases was associated with significantly more cases contaminated with Gram-negative bacteria (GNB) (30% vs. 10%, p < 0.001), a greater risk of GNB case contamination (OR: 2.91, p < 0.001. 95% CI: 1.72-4.92), and a higher quantity of GNB in cases (mean colony-forming unit/case ± SD: 28,286 ± 131,935 vs. 6477 ± 60,447, p < 0.001). Lens case hygiene can be improved by effective communication of instructions. Contact lens wearers should be actively discouraged from rinsing contact lens cases with tap water because of the increased risk of GNB contamination.

Measurement accuracy of a stressed contact lens during its relaxation period

NASA Astrophysics Data System (ADS)

Compertore, David C.; Ignatovich, Filipp V.

2018-02-01

We examine the dioptric power and transmitted wavefront of a contact lens as it releases its handling stresses. Handling stresses are introduced as part of the contact lens loading process and are common across all contact lens measurement procedures and systems. The latest advances in vision correction require tighter quality control during the manufacturing of the contact lenses. The optical power of contact lenses is one of the critical characteristics for users. Power measurements are conducted in the hydrated state, where the lens is resting inside a solution-filled glass cuvette. In a typical approach, the contact lens must be subject to long settling times prior to any measurements. Alternatively, multiple measurements must be averaged. Apart from potential operator dependency of such approach, it is extremely time-consuming, and therefore it precludes higher rates of testing. Comprehensive knowledge about the settling process can be obtained by monitoring multiple parameters of the lens simultaneously. We have developed a system that combines co-aligned a Shack-Hartmann transmitted wavefront sensor and a time-domain low coherence interferometer to measure several optical and physical parameters (power, cylinder power, aberrations, center thickness, sagittal depth, and diameter) simultaneously. We monitor these parameters during the stress relaxation period and show correlations that can be used by manufacturers to devise methods for improved quality control procedures.

Improved contact lens disinfection by exposure to violet radiation.

PubMed

Hoenes, Katharina; Stangl, Felix; Gross, Andrej; Hessling, Martin

2016-01-01

Conventional procedures for contact lens disinfection, based on solutions with aggressive chemical ingredients, not only affect microorganisms but operate likewise damaging towards the epithelial eye surface. The aim of this study was to evaluate the applicability of an alternative or complementary disinfection procedure for contact lenses based on irradiation within the visible wavelength range. Suspensions of S. auricularis, B. subtilis and E. coli were exposed to 405 nm irradiation, for determining the disinfection efficacy. Surviving rates were analyzed by membrane filtration as well as a semi-quantitative analysis using DipSlides. A significant antibacterial effect of the 405 nm irradiation is verifiable for all probed bacteria. Using S. auricularis, there has been no colony forming after an irradiation exposure of 2 hours. The hitherto existing results give reason for the assumption that violet LEDs integrated in contact lens cases will provide a subsidiary disinfection activity and maybe even offer the reduction of chemical ingredients in lens cleaning solutions to become gentler to the eye. In addition the danger of a rerise of the germ concentration after the completion of the disinfection procedure will be reduced.

The Disinfecting Potential of Contact Lens Soutions used by Sultan Qaboos University Students

PubMed Central

Nzeako, B. C.; Al-Sumri, Sara H.

2011-01-01

Objectives: This study aimed to determine the disinfecting potential of some contact lens solutions used by some university students in Oman. Methods: This work was carried out from January to June 2010 in the Department of Microbiology & Immunology, College of Medicine and Health Sciences, Sultan Qaboos University, Oman. Fifty disinfecting solutions, in which contact lenses were disinfected according to the manufacturers’ instructions, were collected from the students and plated on various microbiological culture media. Bacterial isolates were identified by API-20E, API-20NE and Phoenix automated systems while fungi were identified by their cultural characteristics and biochemistry. Results: From 98 isolates, Pseudomonas aeruginosa was 23.5%; Penicillium, 13%; Candida species, 9.2%; coagulase negative staphylococci, 9.2%; Serratia marcescens, 6.1%; Bacillus, 5.1%; Aspergillus flavus, 5.1%; Serratia liquefaciens, Pseudomonas fluorescens, Enterobacter cloacae and Aspergillus niger, 4.1% each; Chryseomonas luteola and Chryseomonas indologenes, 3.1% each; Stenotrophomonas maltophilia, Serratia odorifera, 2.0% each; Enterobacter aerogenes and Klebsiella pneumoniae, 1% each. Most isolates (65%) came from polyhexanide containing solutions. Conclusion: Contact lens disinfecting solutions with the same formulations, but manufactured by different companies, possessed different disinfecting potentials. PMID:21969898

Salicylate inhibition of acanthamoebal attachment to contact lenses.

PubMed

Beattie, Tara K; Tomlinson, Alan; Seal, David V; McFadyen, Angus K

2011-12-01

Sodium salicylate has shown potential as a component of contact lens care solutions designed to reduce Acanthamoebal attachment to contact lenses. This study determined the minimum effective concentration required to significantly reduce amoebal attachment. Different concentrations of sodium salicylate (10, 15, and 20 mM) were applied during exposure of unworn or bacterial biofilm-coated hydrogel contact lenses to Acanthamoeba castellanii trophozoites. Salicylate was applied at stage 1 intervention during biofilm formation on lenses, at stage 2 intervention during amoebal exposure, or at both stages. A significant reduction in amoebal attachment was achieved when 10 mM salicylate was included during stage 1 alone; however, 15 mM was required for stage 2 intervention to significantly reduce attachment to clean or biofilm-coated lenses. For stages 1 and 2 combined intervention, 10 mM sodium salicylate produced a significant reduction in amoebal attachment. In situ, within a contact lens case, biofilm formation and amoebal attachment would occur concurrently; therefore, stages 1 and 2 intervention would be closest to the real-life situation, thus indicating that 10 mM of salicylate would be an effective minimum concentration for reducing amoebal attachment to hydrogel contact lenses. Inclusion of components in contact lens care solution, such as sodium salicylate, which reduce Acanthamoebal attachment, has the potential to enhance effectiveness, particularly where amoebicidal efficacy may be limited, thus reducing the risk of contact lens-associated Acanthamoebal infection.

The clinical and cellular basis of contact lens-related corneal infections

PubMed Central

Robertson, Danielle M; Cavanagh, H Dwight

2008-01-01

Microbial keratitis (MK) is the most visually devastating complication associated with contact lens wear. Pseudomonas aeruginosa (PA) is highly invasive in the corneal epithelium and is responsible for more than half of the reported cases of contact lens-related MK. To protect against Pseudomonas-mediated MK, the corneal epithelium has evolved overlapping defense mechanisms that function to protect the ocular surface from microbial invasion. Research has shown that contact lens wear disrupts these protective mechanisms through breakdown of normal homeostatic surface renewal as well as damaging the corneal surface, exposing underlying cell membrane receptors that bind and internalize PA through the formation of lipid rafts. Human clinical trials have shown that initial adherence of PA with resulting increased risk for microbial infection is mediated in part by contact lens oxygen transmissibility. Recently, chemical preserved multipurpose solutions (MPS) have been implicated in increasing PA adherence to corneal epithelial cells, in addition to inducing significant levels of toxic staining when used in conjunction with specific silicone hydrogel lenses. This review summarizes what is currently known about the relationship between contact lenses, the corneal epithelium, MPS, and infection. PMID:19277209

Patient Compliance During Contact Lens Wear: Perceptions, Awareness, and Behavior

PubMed Central

Bui, Thai H.; Cavanagh, H. Dwight; Robertson, Danielle M.

2011-01-01

Objectives Patient noncompliance with recommended hygienic practices in contact lens wear is often considered a significant risk factor for microbial keratitis and adverse contact lens–related events. Despite advancements in lens materials and care solutions, noncompliant behavior continues to hinder efforts to maximize contact lens safety. The objective of this pilot study was to assess the relationship between perceived and actual compliance with awareness of risk and behavior. Methods One hundred sixty-two established contact lens wearers were sequentially evaluated after their routine contact lens examination at the Optometry Clinic at the University of Texas Southwestern Medical Center at Dallas, TX. Each patient was questioned by a single trained interviewer regarding his or her lens care practices and knowledge of risk factors associated with lens wear. Results Eighty-six percent of patients believed they were compliant with lens wear and care practices; 14% identified themselves as noncompliant. Using a scoring model, 32% demonstrated good compliance, 44% exhibited average compliance, and 24% were noncompliant; age was a significant factor (P = 0.020). Only 34% of patients who perceived themselves as compliant exhibited a good level of compliance (P<0.001). Eighty percent of patients reported an awareness of risk factors, but awareness did not influence negative behavior. Replacing the lens case was the only behavior associated with a positive history for having experienced a prior contact lens–related complication (P = 0.002). Conclusions Perceived compliance is not an indicator for appropriate patient behavior. A large proportion of patients remain noncompliant despite awareness of risk. Education alone is not a sufficient strategy to improve behavior; newer approaches aimed at improving compliance with lens care practices are urgently needed. PMID:20935569

Contact lens strategies for the patient with dry eye.

PubMed

Sindt, Christine W; Longmuir, Reid A

2007-10-01

Dry eye is the most common reason for contact lens (CL) discontinuation, and the patient with pre-existing dry eye presents particular challenges to the CL fitter. Poor tear film quality/stability, oxygen deprivation, lens deposits, and adverse reactions to CL solutions all contribute to dry eye, and lid disease, allergies, environmental factors, and medications can further hamper successful CL wear by the patient with dry eye. Health and comfort of the ocular surface is affected by the water content, ionicity, oxygen permeability, and modulus of elasticity of the lens, as well as by surface characteristics, such as protein, lipid, and mucin deposition; protein adsorption; and wettability. The choice of CL cleaning solutions with regard to action, cytotoxicity, and biocompatibility are as important as the choice of the CL itself. With appropriate management of the lid, meibomian gland, and ocular surface conditions that produce dry eye, careful selection of lenses and solutions, and vigilant follow-up, successful CL wear should be achievable for the dry eye patient.

Optical high acidity sensor

DOEpatents

Jorgensen, Betty S.; Nekimken, Howard L.; Carey, W. Patrick; O'Rourke, Patrick E.

1997-01-01

An apparatus and method for determining acid concentrations in solutions having acid concentrations of from about 0.1 Molar to about 16 Molar is disclosed. The apparatus includes a chamber for interrogation of the sample solution, a fiber optic light source for passing light transversely through the chamber, a fiber optic collector for receiving the collimated light after transmission through the chamber, a coating of an acid resistant polymeric composition upon at least one fiber end or lens, the polymeric composition in contact with the sample solution within the chamber and having a detectable response to acid concentrations within the range of from about 0.1 Molar to about 16 Molar, a measurer for the response of the polymeric composition in contact with the sample solution, and, a comparer of the measured response to predetermined standards whereby the acid molarity of the sample solution within the chamber can be determined. Preferably, a first lens is attached to the end of the fiber optic light source, the first lens adapted to collimate light from the fiber optic light source, and a second lens is attached to the end of the fiber optic collector for focusing the collimated light after transmission through the chamber.

Optical high acidity sensor

DOEpatents

Jorgensen, B.S.; Nekimken, H.L.; Carey, W.P.; O`Rourke, P.E.

1997-07-22

An apparatus and method for determining acid concentrations in solutions having acid concentrations of from about 0.1 Molar to about 16 Molar is disclosed. The apparatus includes a chamber for interrogation of the sample solution, a fiber optic light source for passing light transversely through the chamber, a fiber optic collector for receiving the collimated light after transmission through the chamber, a coating of an acid resistant polymeric composition upon at least one fiber end or lens, the polymeric composition in contact with the sample solution within the chamber and having a detectable response to acid concentrations within the range of from about 0.1 Molar to about 16 Molar, a measurer for the response of the polymeric composition in contact with the sample solution, and a comparer of the measured response to predetermined standards whereby the acid molarity of the sample solution within the chamber can be determined. Preferably, a first lens is attached to the end of the fiber optic light source, the first lens adapted to collimate light from the fiber optic light source, and a second lens is attached to the end of the fiber optic collector for focusing the collimated light after transmission through the chamber. 10 figs.

In Vitro Effect of Lysozyme on Albumin Deposition to Hydrogel Contact Lens Materials.

PubMed

Babaei Omali, Negar; Subbaraman, Lakshman N; Heynen, Miriam; Fadli, Zohra; Coles-Brennan, Chantal; Jones, Lyndon W

2017-11-01

Albumin deposition on contact lenses could be detrimental to contact lens (CL) wear because this may increase the risk of bacterial binding and reduce comfort. Lysozyme deposition on selected lens materials would reduce albumin deposition on lenses. This study aims to determine if lysozyme deposition on CLs could act as a barrier against subsequent albumin adsorption, using an in vitro model. Six hydrogel CL materials (etafilcon A, polymacon, nelfilcon A, omafilcon A, ocufilcon B, and nesofilcon A) were evaluated. Four CLs of each type were soaked in lysozyme solution for 16 hours at 37°C. Lysozyme-coated lenses were then placed in vials with 1.5 mL of artificial tear solution containing I-labeled albumin for 16 hours at 37°C with shaking. Four uncoated lenses of each type were used as controls. Lenses soaked in radiolabeled albumin were rinsed in a phosphate-buffered saline solution, and radioactive counts were measured directly on lenses using a gamma counter. Albumin uptake on lenses was measured using a calibration curve by plotting radioactive counts versus protein concentration. Results are reported as mean ± SD. Lysozyme-coated etafilcon A lenses exhibited lower levels of deposited albumin than uncoated etafilcon A lenses (58 ± 12 vs. 84 ± 5 ng/lens; P < .05). There were no differences in albumin adsorption between control (uncoated) and lysozyme-coated polymacon (105 ± 10 vs. 110 ± 34 ng/lens), nelfilcon A (51 ± 7 vs. 42 ± 20 ng/lens), omafilcon A (90 ± 20 vs. 80 ± 38 ng/lens), ocufilcon B (87 ± 20 vs. 115 ± 50 ng/lens), and nesofilcon A (170 ± 29 vs. 161 ± 10 ng/lens) lens materials (P > .05). Uncoated nesofilcon A lenses deposited the highest amount of albumin when compared with other uncoated lenses (P < .05). This study demonstrates that lysozyme deposited onto etafilcon A resists the deposition of albumin, which may potentially be beneficial to CL wearers.

A Novel Anti-Spoofing Solution for Iris Recognition Toward Cosmetic Contact Lens Attack Using Spectral ICA Analysis.

PubMed

Hsieh, Sheng-Hsun; Li, Yung-Hui; Wang, Wei; Tien, Chung-Hao

2018-03-06

In this study, we maneuvered a dual-band spectral imaging system to capture an iridal image from a cosmetic-contact-lens-wearing subject. By using the independent component analysis to separate individual spectral primitives, we successfully distinguished the natural iris texture from the cosmetic contact lens (CCL) pattern, and restored the genuine iris patterns from the CCL-polluted image. Based on a database containing 200 test image pairs from 20 CCL-wearing subjects as the proof of concept, the recognition accuracy (False Rejection Rate: FRR) was improved from FRR = 10.52% to FRR = 0.57% with the proposed ICA anti-spoofing scheme.

Effects of multipurpose solutions on the adhesion of Acanthamoeba to rigid gas permeable contact lenses.

PubMed

Lee, Ga-Hyun; Yu, Hak-Sun; Lee, Ji-Eun

2016-03-01

To evaluate the effect of multipurpose contact lens care solutions (MPSs) on the adhesion of Acanthamoeba to rigid gas permeable (RGP) contact lenses. Acanthamoeba castellanii (AC) trophozoites were inoculated onto untreated RGP contact lenses (FP, Extra, or Menicon Z), and numbers of trophozoites adhering to lenses were counted under a phase contrast microscope at 18 h post-inoculation (controls). Similarly, adhering trophozoites were counted at 6 h post-inoculation on each of the three RGP lens types with one of three MPSs (Boston Simplus, Menicare Plus, and O2 Care). Scanning electron microscopic examinations were performed to compare lens surfaces. Adhesion of AC trophozoites to untreated FP was greater than to untreated Extra or Menicon Z. Surfaces of Extra and Menicon Z lenses were waxier, smoother, and more homogeneous than those of FP lenses. After treatment with Boston Simplus, adhesion of AC trophozoites was significantly reduced for all lens types as compared with controls (p < 0.0001). Treatments with Menicare Plus or O2 Care reduced the number of adherent AC trophozoites significantly on FP lenses only as compared with controls (p < 0.0001). The adhesion rates of AC trophozoites to RGP lenses depended on lens surfaces. Boston Simplus reduced the adhesion rate of AC trophozoites more than Menicare Plus or O2 Care. Appropriate RGP lens and MPS selection could decrease the prevalence of Acanthamoeba keratitis. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

Molecular characterization, biofilm analysis and experimental biofouling study of Fusarium isolates from recent cases of fungal keratitis in New York State

PubMed Central

Dyavaiah, Madhu; Ramani, Rama; Chu, David S; Ritterband, David C; Shah, Mahendra K; Samsonoff, William A; Chaturvedi, Sudha; Chaturvedi, Vishnu

2007-01-01

Background To characterize Fusarium isolates from recent cases of fungal keratitis in contact lens wearers, and to investigate fungal association with MoistureLoc solution. Methods We studied six fungal isolates from recent cases of keratitis in New York State. The isolates were characterized by nucleotide sequencing and phylogenetic analyses of multiple genes, and then typed using minisatellite and microsatellite probes. Experimental fungal biofilm formation was tested by standard methods. MoistureLoc solutions were tested in biofouling studies for their efficacy in elimination of Fusarium contamination. Results Fusarium solani – corneal ulcers (2 isolates), lens case (1 isolate), and F. oxysporum – corneal ulcer (1 isolate), eye (1 isolate), were recovered from five patients. An opened bottle of MoistureLoc solution provided by a patient also yielded F. solani. Two distinct genotypes of F. solani as well as of F. oxysporum were present in the isolated strains. Remarkably, F. solani strains from the lens case and lens solution in one instance were similar, based on phylogenetic analyses and molecular typing. The solution isolate of F. solani formed biofilm on contact lenses in control conditions, but not when co-incubated with MoistureLoc solution. Both freshly opened and 3-month old MoistureLoc solutions effectively killed F. solani and F. oxysporum, when fungal contamination was simulated under recommended lens treatment regimen (4-hr). However, simulation of inappropriate use (15 – 60 min) led to the recovery of less than 1% of original inoculum of F. solani or F. oxysporum. Conclusion Temporary survival of F. solani and F. oxysporum in MoistureLoc suggested that improper lens cleaning regimen could be a possible contributing factor in recent infections. PMID:17263885

Nonadhesive, silica nanoparticles-based brush-coated contact lens cases--compromising between ease of cleaning and microbial transmission to contact lenses.

PubMed

Qu, Wenwen; Hooymans, Johanna M M; Qiu, Jun; de-Bont, Nik; Gelling, Onko-Jan; van der Mei, Henny C; Busscher, Henk J

2013-05-01

Surface properties of lens cases are determinant for their cleanability and for microbial transmission from lens cases to contact lenses (CLs). PEG-polymer-brush-coatings are known to decrease microbial adhesion more than other surface-coatings. Here, we applied a robust, silica nanoparticles-based brush-coating to polypropylene cases to evaluate their ease of cleaning and probability of bacterial transmission to CLs. Adhesion forces of nine bacterial strains (Pseudomonas, Staphylococci, and Serratia) to rigid CLs, polypropylene, and silica nanoparticles-based brush-coated polypropylene were measured using atomic-force-microscopy and subjected to Weibull analyses to yield bacterial transmission probabilities. Biofilms of each strain were grown in coated and uncoated cases and rinsed with a NaCl or antimicrobial lens care solution. Residual, viable organisms were quantified. Bacterial adhesion forces of all strains were significantly, up to tenfold smaller on brush-coated than on uncoated polypropylene. This yielded, higher transmission probabilities to a CL, but mild-rinsing yielded 10-100 fold higher removal of bacteria from brush-coated than from polypropylene cases. Moreover, due to weak adhesion forces, bacteria on brush-coated cases were two-to-three fold more susceptible to an antimicrobial lens care solution than on polypropylene cases. Therewith, the design of lens case surfaces is a compromise between ease of cleaning and transmission probability to CLs. Copyright © 2013 Wiley Periodicals, Inc.

A Novel Anti-Spoofing Solution for Iris Recognition Toward Cosmetic Contact Lens Attack Using Spectral ICA Analysis

PubMed Central

Hsieh, Sheng-Hsun; Wang, Wei; Tien, Chung-Hao

2018-01-01

In this study, we maneuvered a dual-band spectral imaging system to capture an iridal image from a cosmetic-contact-lens-wearing subject. By using the independent component analysis to separate individual spectral primitives, we successfully distinguished the natural iris texture from the cosmetic contact lens (CCL) pattern, and restored the genuine iris patterns from the CCL-polluted image. Based on a database containing 200 test image pairs from 20 CCL-wearing subjects as the proof of concept, the recognition accuracy (False Rejection Rate: FRR) was improved from FRR = 10.52% to FRR = 0.57% with the proposed ICA anti-spoofing scheme. PMID:29509692

The comfort factor: assessing patient satisfaction with Opti-Free vs other contact lens cleaning products.

PubMed

Yeaton, K

1994-01-01

Many patients cite comfort as a primary factor in their success or failure with soft contact lenses. In an effort to further meet the needs of these patients, eye-care professionals must place more emphasis on dispensing a lens type and lens-care system that maximize patient satisfaction and thus provide a higher quality of service. This study delineated patient-defined quality and comfort as they relate to lens-care solutions. Five hundred ninety-nine U.S. practices were each asked to switch 25 of their patients to Opti-Free Lens Care from their currently used lens-care system (52% ReNu Multi-Purpose Solution, 20% AOSept System) for 2 weeks. Data were collected from 14,455 patients who completed the post-trial interview. At the time of the callback interview, 81% of respondents (78% ReNu users, 82% AOSept users) were using the Opti-Free System. Of these patients, 85% (84% previous ReNu users, 87% previous AOSept users) rated Opti-Free Lens Care more comfortable than or as comfortable as their previous system. These findings demonstrate differences in patient comfort among Opti-Free, AOSept, and ReNu. Eye-care professionals should consider relative comfort when dispensing lens-care systems, as this may affect patient-defined quality.

Corneal and conjunctival epithelial staining in hydrogel contact lens wearers.

PubMed

Brautaset, Rune L; Nilsson, Maria; Leach, Norman; Miller, William L; Gire, Anisa; Quintero, Sam; Bergmanson, Jan P G

2008-11-01

The purpose of this study was to investigate the prevalence of conjunctival and corneal epithelial staining in soft contact lens wearers and to see if staining could be associated with factors such as type of lens worn, wearing time, care system, age, and sex. The records of 338 adapted hydrogel contact lens wearers were examined retrospectively. Conjunctival staining was found to be present in 32.5% of the subjects and corneal staining was found to be present in 19.5% of subjects. None of the subjects had staining above grade 2 using the Cornea and Contact Lens Research Unit scale. Because of the low prevalence of staining, the low grading of staining found and the large variation in refractive power, lens type worn, wearing modality, and solution used statistical analysis for association between staining and different factors could only be performed for the association between sex and staining and between corneal and conjunctival staining. However, no statistical significant association could be demonstrated. Despite the low prevalence of staining the conjunctiva and cornea should be examined carefully in contact lens wearers and prospective wearers because the conjunctival and corneal epithelium serve as protective barriers for the underlying layers of the cornea and conjunctiva. To allow comparison of data obtained in different studies assessing corneal staining, it is recommended that clinicians develop and adopt a universal standard protocol for this measure.

Influence of Amphibian Antimicrobial Peptides and Short Lipopeptides on Bacterial Biofilms Formed on Contact Lenses

PubMed Central

Maciejewska, Magdalena; Bauer, Marta; Neubauer, Damian; Kamysz, Wojciech; Dawgul, Malgorzata

2016-01-01

The widespread use of contact lenses is associated with several complications, including ocular biofilm-related infections. They are very difficult to manage with standard antimicrobial therapies, because bacterial growth in a biofilm is associated with an increased antibiotic resistance. The principal aim of this study was to evaluate the efficacy of antimicrobial peptides (AMPs) in eradication of bacterial biofilms formed on commercially available contact lenses. AMPs were synthesized according to Fmoc/tBu chemistry using the solid-phase method. Minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) of the compounds were determined. Anti-biofilm activity of the antimicrobial peptides determined at different temperatures (25 °C and 37 °C) were compared with the effectiveness of commercially available contact lens solutions. All of the tested compounds exhibited stronger anti-biofilm properties as compared to those of the tested lens solutions. The strongest activity of AMPs was noticed against Gram-positive strains at a temperature of 25 °C. Conclusions: The results of our experiments encourage us toward further studies on AMPs and their potential application in the prophylaxis of contact lens-related eye infections. PMID:28773992

Qualitative identification of rigid gas permeable contact lens materials by densitometry.

PubMed

Arce, C G; Schuman, P D; Schuman, W P

1999-10-01

We describe a practical method to qualitatively identify polymethylmethacrylate (PMMA) and rigid gas permeable (RGP) contact lens materials. By progressive dilution of a saturated saline solution made with distilled or tap water and sodium chloride, we recorded comparative densitometry of rigid contact lens materials using a small hydrometer or by liquid displacement. The method was sensitive enough to separate the polymethylmethacrylate, all silicon-methacrylates, and all but two fluorine-containing silicon-methacrylates. The hydrometer had a precision of three decimals rounded to the nearest 0.005. There was only one RGP product that could have been confused with the PMMA material. Most silicon-methacrylates had lower densities than fluorine containing silicon-methacrylates. Only four of 25 products under 1.117 gm/cm3 contained fluorine. Densitometry with a hydrometer is an effective non-destructive method to identify RGP materials and to verify their quality. The method is easier when lens blanks are tested, but in spite of differences in shape, size, and weight, densitometry may also be used with new or used contact lenses. Its simplicity and low cost makes densitometry feasible for any contact lens laboratory or clinic to use on a routine basis. Only silicon-methacrylates had an inverse relationship between density and oxygen permeability. As the silicon content of the contact lens increases, the Dk increases and the density decreases.

Compliance and hygiene behaviour among soft contact lens wearers in the Maldives.

PubMed

Gyawali, Rajendra; Nestha Mohamed, Fathimath; Bist, Jeewanand; Kandel, Himal; Marasini, Sanjay; Khadka, Jyoti

2014-01-01

Significant levels of non-compliance and poor hygiene among contact lens wearers have been reported previously from different parts of the world. This survey aimed at identifying the scope of hygiene and non-compliant behaviour of soft contact lens wearers in the Maldives. Established soft lens wearers attending two eye clinics in Male' city, were interviewed in office or via telephone. A set of interviewer-administered questions was used to access the subjective response on compliance and hygiene behaviour (hand and lens case hygiene, water exposure, adherence to lens replacement schedule, dozing and overnight wear, awareness of aftercare visits and reuse of disinfecting solution). Participants were also asked to rate themselves as a contact lens user based on their perceived compliance and hygiene practices. Out of 107 participants, 79 (74.8 per cent) were interviewed in the office and the rest via telephone. The majority of lens wearers were female, office workers and students, with a mean age of 20.64 ± 4.4 years. Mean duration of lens wear was 28.04 ± 8.36 months. Most of them were using spherical lenses (86.9 per cent) on a daily wear basis (96.3 per cent). Major reported forms of non-compliance were poor hand hygiene (60.7 per cent), lack of aftercare awareness (39.3 per cent), water exposure (35.5 per cent) and over-use of lenses (24.3 per cent). While females were more likely to overuse their lenses than males (p < 0.005), other socio-demographic factors were not associated with reported non-compliance. Although around 90 per cent of the participants considered themselves average or good contact lens wearers, most exhibited some form of non-compliant and poor hygienic behaviour. A significant number of Maldivian contact lens wearers exhibited poor levels of hygiene and compliance with contact lenses and lens care systems. An effective educational reinforcement strategy needs to be developed to modify lens wearers' non-compliance. © 2013 The Authors. Clinical and Experimental Optometry © 2013 Optometrists Association Australia.

A comparison of regimen methods for the removal and inactivation of bacteria, fungi and Acanthamoeba from two types of silicone hydrogel lenses.

PubMed

Kilvington, Simon; Lonnen, James

2009-04-01

To compare the antimicrobial efficacy of commercial contact lens solutions when used according to the manufacturers' recommended regimens with two types of silicone hydrogel lenses. Four multipurpose contact lens care solutions were examined, representing manufacturer recommended regimens of "rub & rinse", "no rub, rinse" or "no rub, no rinse". Test organisms were Pseudomonas aeruginosa, Serratia marcescens, Staphylococcus aureus, Fusarium solani, Candida albicans and Acanthamoeba castellanii (trophozoites and cysts). Organisms, in the presence of organic soil, were inoculated on to Acuvue Oasys or Air Optix lenses and subjected to the solution manufacturer's recommended regimen. The number of surviving organisms on the lenses and in the soak solution was enumerated in accordance with ISO 14729. ISO 14729 dictates that for a given organism the combined average number of surviving microbes from the lenses and disinfectant soaking solution must be

Contact lens disinfecting solutions antibacterial efficacy: comparison between clinical isolates and the standard ISO ATCC strains of Pseudomonas aeruginosa and Staphylococcus aureus.

PubMed

Mohammadinia, M; Rahmani, S; Eslami, G; Ghassemi-Broumand, M; Aghazadh Amiri, M; Aghaie, Gh; Tabatabaee, S M; Taheri, S; Behgozin, A

2012-02-01

To evaluate the disinfectant properties of the three multipurpose contact lens disinfecting solutions available in Iran, against clinical isolates and the standard ISO ATCC strains of Pseudomonas aeruginosa and Staphylococcus aureus, based on the international organization for standardization (ISO) 14729 guidelines. Three multipurpose solutions that were tested were ReNu Multiplus, Solo Care Aqua and All-Clean Soft. The test solutions were challenged with clinical isolates and the standard strains of P. aeruginosa(ATCC 9027) and S. aureus(ATCC 6538), based on the ISO Stand-alone procedure for disinfecting products. Solutions were sampled for surviving microorganisms at manufacturer's minimum recommended disinfection time. The number of viable organisms was determined and log reductions calculated. All of the three test solutions in this study provided a reduction greater than the required mean 3.0 logarithmic reduction against the recommended standard ATCC strains of P. aeruginosa and S. aureus. Antibacterial effectiveness of Solo Care Aqua and All-Clean Soft against clinical isolates of P. aeruginosa and S. aureus were acceptable based on ISO 14729 Stand-alone test. ReNu MultiPlus showed a minimum acceptable efficacy against the clinical isolate of S. aureus, but did not reduce the clinical isolate by the same amount. Although the contact lens disinfecting solutions meet/exceed the ISO 14729 Stand-alone primary acceptance criteria for standard strains of P. aeruginosa and S. aureus, their efficacy may be insufficient against clinical isolates of these organisms.

Contact lens disinfecting solutions antibacterial efficacy: comparison between clinical isolates and the standard ISO ATCC strains of Pseudomonas aeruginosa and Staphylococcus aureus

PubMed Central

Mohammadinia, M; Rahmani, S; Eslami, G; Ghassemi-Broumand, M; Aghazadh Amiri, M; Aghaie, Gh; Tabatabaee, S M; Taheri, S; Behgozin, A

2012-01-01

Purpose To evaluate the disinfectant properties of the three multipurpose contact lens disinfecting solutions available in Iran, against clinical isolates and the standard ISO ATCC strains of Pseudomonas aeruginosaand Staphylococcus aureus, based on the international organization for standardization (ISO) 14729 guidelines. Methods Three multipurpose solutions that were tested were ReNu Multiplus, Solo Care Aqua and All-Clean Soft. The test solutions were challenged with clinical isolates and the standard strains of P. aeruginosa(ATCC 9027) and S. aureus(ATCC 6538), based on the ISO Stand-alone procedure for disinfecting products. Solutions were sampled for surviving microorganisms at manufacturer's minimum recommended disinfection time. The number of viable organisms was determined and log reductions calculated. Results All of the three test solutions in this study provided a reduction greater than the required mean 3.0 logarithmic reduction against the recommended standard ATCC strains of P. aeruginosaand S. aureus. Antibacterial effectiveness of Solo Care Aqua and All-Clean Soft against clinical isolates of P. aeruginosaand S. aureuswere acceptable based on ISO 14729 Stand-alone test. ReNu MultiPlus showed a minimum acceptable efficacy against the clinical isolate of S. aureus, but did not reduce the clinical isolate by the same amount. Conclusions Although the contact lens disinfecting solutions meet/exceed the ISO 14729 Stand-alone primary acceptance criteria for standard strains of P. aeruginosaand S. aureus, their efficacy may be insufficient against clinical isolates of these organisms. PMID:22094301

Impact of Cosmetics on the Surface Properties of Silicone Hydrogel Contact Lenses.

PubMed

Srinivasan, Sruthi; Otchere, Heinz; Yu, Mili; Yang, Jeffery; Luensmann, Doerte; Jones, Lyndon

2015-07-01

This study evaluated the impact of various cosmetics on the surface properties of silicone hydrogel (SiHy) contact lens materials. In this in vitro experiment, 7 SiHy contact lens materials were coated with 1 of 9 cosmetics, including common hand creams (3), eye makeup removers (3), and mascaras (3). Dark-field microscopy images were taken to determine pixel brightness (PB) after cosmetic exposure, which describes the visible surface deposition (n=6 for each lens type), with a higher PB indicating increased deposition. The sessile drop technique was used to determine the advancing contact angle (CA). Measurements were repeated for both methods after a single peroxide-based cleaning cycle. Pixel brightness was significantly higher for mascara-coated lenses compared with the other cosmetic products (P<0.01). The peroxide-based lens care solution removed most deposits from the nonwaterproof mascara for 4 lens types, whereas deposits remained relatively unchanged for 1 waterproof mascara (P>0.05). Hand creams and makeup remover had minimal impact on PB. Changes in CA measurements after cosmetic application were highly lens dependent. Hand creams caused primarily a decrease in CA for 5 of the 7 lens types, whereas 1 of the waterproof mascaras caused a significant increase of 30 to 50° for 3 lens types. Some mascara-lens combinations resulted in increased CA and PB, which could have an impact on in vivo lens performance. Nonwaterproof mascara was mostly removed after a cleaning cycle. Further research is needed to understand the clinical implications for SiHy lens wearers using cosmetics.

Surface versus bulk activity of lysozyme deposited on hydrogel contact lens materials in vitro.

PubMed

Omali, Negar Babaei; Subbaraman, Lakshman N; Heynen, Miriam; Ng, Alan; Coles-Brennan, Chantal; Fadli, Zohra; Jones, Lyndon

2018-04-30

To determine and compare the levels of surface versus bulk active lysozyme deposited on several commercially available hydrogel contact lens materials. Hydrogel contact lens materials [polymacon, omafilcon A, nelfilcon A, nesofilcon A, ocufilcon and etafilcon A with polyvinylpyrrolidone (PVP)] were incubated in an artificial tear solution for 16 h. Total activity was determined using a standard turbidity assay. The surface activity of the deposited lysozyme was determined using a modified turbidity assay. The amount of active lysozyme present within the bulk of the lens material was calculated by determining the difference between the total and surface active lysozyme. The etafilcon A materials showed the highest amount of total lysozyme activity (519 ± 8 μg/lens, average of Moist and Define), followed by the ocufilcon material (200 ± 5 μg/lens) and these two were significantly different from each other (p < 0.05). The amount of surface active lysozyme on etafilcon and ocufilcon lens materials was significantly higher than that found on all other lenses (p < 0.05). There was no active lysozyme quantified in the bulk of the nelfilcon material, as all of the active lysozyme was found on the surface (1.7 ± 0.3 μg/lens). In contrast, no active lysozyme was quantified on the surface of polymacon, with all of the active lysozyme found in the bulk of the lens material (0.6 ± 0.6 μg/lens). The surface and bulk activity of lysozyme deposited on contact lenses is material dependent. Lysozyme deposited on ionic, high water content lens materials such as etafilcon A show significantly higher surface and bulk activity than many other hydrogel lens materials. Copyright © 2018 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Contact lens wear by Royal Air Force aircrew in World War II.

PubMed

Pearson, Richard M

2014-04-01

To provide an overview of the use of contact lenses by RAF aircrew in World War II by identifying some of the fitters and wearers and appraising the clinical results that they achieved. A wide-ranging literature search was undertaken that encompassed peer-reviewed journals, non-refereed publications, books, official publications, newspapers and archived documents. Thirty-one aircrew are known to have worn sealed scleral lenses in order to meet the required visual standards. Of these, only two were considered to be completely unsuccessful, one of whom was unilaterally aphakic. One additional case of undisclosed contact lens wear was found and the identity of this officer was established. Brief biographies of a few pilots establish the context of their contact lens wear. Overall, the results of scleral lens wear were variable reflecting those achieved by civilian patients of the period. While three men complained of discomfort due to heat and glare, one pilot experienced no photophobia when flying above white clouds in brilliant sunshine and another found no difficulty caused by altitude or tropical climate. Wearing time ranged from about 2h to 16, or more, hours. In about a third of the cases, wearing time was limited due to the onset of a form of contact lens induced-epithelial oedema known as Sattler's veil and effective solutions to this problem were not implemented until after the war. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Design of retinal-projection-based near-eye display with contact lens.

PubMed

Wu, Yuhang; Chen, Chao Ping; Mi, Lantian; Zhang, Wenbo; Zhao, Jingxin; Lu, Yifan; Guo, Weiqian; Yu, Bing; Li, Yang; Maitlo, Nizamuddin

2018-04-30

We propose a design of a retinal-projection-based near-eye display for achieving ultra-large field of view, vision correction, and occlusion. Our solution is highlighted by a contact lens combo, a transparent organic light-emitting diode panel, and a twisted nematic liquid crystal panel. Its design rules are set forth in detail, followed by the results and discussion regarding the field of view, angular resolution, modulation transfer function, contrast ratio, distortion, and simulated imaging.

Effects of lactoferricin B against keratitis-associated fungal biofilms.

PubMed

Sengupta, Jayangshu; Saha, Suman; Khetan, Archana; Sarkar, Sujoy K; Mandal, Santi M

2012-10-01

Biofilms are considered as the most important developmental characteristics in ocular infections. Biofilm eradication is a major challenge today to overcome the incidence of drug resistance. This report demonstrates the in vitro ability of biofilm formation on contact lens by three common keratitis-associated fungal pathogens, namely, Aspergillus fumigatus, Fusarium solani, and Candida albicans. Antifungal sensitivity testing performed for both planktonic cells and biofilm revealed the sessile phenotype to be resistant at MIC levels for the planktonic cells and also at higher concentrations. A prototype lens care solution was also found to be partially effective in eradication of the mature biofilm from contact lenses. Lactoferricin B (Lacf, 64 μg/ml), an antimicrobial peptide, exhibited almost no effect on the sessile phenotype. However, the combinatory effect of Lacf with antifungals against planktonic cells and biofilms of three fungal strains that were isolated from keratitis patients exhibited a reduction of antifungal dose more than eightfold. Furthermore, the effect of Lacf in lens care solution against biofilms in which those strains formed was eradicated successfully. These results suggest that lactoferricin B could be a promising candidate for clinical use in improving biofilm susceptibility to antifungals and also as an antibiofilm-antifungal additive in lens care solution.

Direct Laser Writing of Nanophotonic Structures on Contact Lenses.

PubMed

AlQattan, Bader; Yetisen, Ali K; Butt, Haider

2018-04-24

Contact lenses are ubiquitous biomedical devices used for vision correction and cosmetic purposes. Their application as quantitative analytical devices is highly promising for point-of-care diagnostics. However, it is a challenge to integrate nanoscale features into commercial contact lenses for application in low-cost biosensors. A neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (1064 nm, 3 ns pulse, 240 mJ) in holographic interference patterning mode was utilized to produce optical nanostructures over the surface of a hydrogel contact lens. One-dimensional (925 nm) and two-dimensional (925 nm × 925 nm) nanostructures were produced on contact lenses and analyzed by spectroscopy and angle-resolve measurements. The holographic properties of these nanostructures were tested in ambient moisture, fully hydrated, and artificial tear conditions. The measurements showed a rapid tuning of optical diffraction from these nanostructures from 41 to 48°. The nanostructures were patterned near the edges of the contact lens to avoid any interference and obstruction to the human vision. The formation of 2D nanostructures on lenses increased the diffraction efficiency by more than 10%. The versatility of the holographic laser ablation method was demonstrated by producing four different 2D nanopattern geometries on contact lenses. Hydrophobicity of the contact lens was characterized by contact angle measurements, which increased from 59.0° at pristine condition to 62.5° at post-nanofabrication. The holographic nanostructures on the contact lens were used to sense the concentration of Na + ions. Artificial tear solution was used to simulate the conditions in dry eye syndrome, and nanostructures on the contact lenses were used to detect the electrolyte concentration changes (±47 mmol L -1 ). Nanopatterns on a contact lens may be used to sense other ocular diseases in early stages at point-of-care settings.

Antimicrobial efficacy assessment of multi-use solution to disinfect hydrophilic contact lens, in vitro.

PubMed

Lui, Aline Cristina Fioravanti; Netto, Adamo Lui; Silva, Cely Barreto da; Hida, Richard; Mendes, Thais Sousa; Lui, Giovana Arlene Fioravanti; Gemperli, Daniela Barbosa; Vital, Enderson Dantas

2009-01-01

To evaluate the efficacy of disinfecting solutions in hydrophilic contact lenses (CL). Two multi-use solutions denominated solution A (0.001% polyquaternium-1 and 0.0005% myristamidopropyl dimethylamine) and solution B (0.0001% polyaminopropyl biguanide) were used. The solutions were tested in hydrophilic contact lenses infected with Pseudomonas aeruginosa (ATCC27583), Staphylococcus epidermidis (ATCC1226), Klebsiella pneumoniae (ATCC13883), Staphylococcus aureus (ATCC25923) and Candida albicans (ATCC 10231) and the decrease in microorganisms growth after the hydrophilic contact lenses were cleaned with the respective solutions was verified. The manufacture's instructions were followed. A decrease of 90% of Pseudomonas aeruginosa, Staphylococcus epidermidis, Staphylococcus aureus, Candida albicans and a decrease 100% of Klebsiella pneumoniae was observed. The solutions decreased the amount of microorganisms tested.

Comparative effect of lens care solutions on blink rate, ocular discomfort and visual performance.

PubMed

Yang, Shun-nan; Tai, Yu-chi; Sheedy, James E; Kinoshita, Beth; Lampa, Matthew; Kern, Jami R

2012-09-01

To help maintain clear vision and ocular surface health, eye blinks occur to distribute natural tears over the ocular surface, especially the corneal surface. Contact lens wearers may suffer from poor vision and dry eye symptoms due to difficulty in lens surface wetting and reduced tear production. Sustained viewing of a computer screen reduces eye blinks and exacerbates such difficulties. The present study evaluated the wetting effect of lens care solutions (LCSs) on blink rate, dry eye symptoms, and vision performance. Sixty-five adult habitual soft contact lens wearers were recruited to adapt to different LCSs (Opti-free, ReNu, and ClearCare) in a cross-over design. Blink rate in pictorial viewing and reading (measured with an eyetracker), dry eye symptoms (measured with the Ocular Surface Disease Index questionnaire), and visual discrimination (identifying tumbling E) immediately before and after eye blinks were measured after 2 weeks of adaption to LCS. Repeated measures anova and mixed model ancova were conducted to evaluate effects of LCS on blink rate, symptom score, and discrimination accuracy. Opti-Free resulted in lower dry eye symptoms (p = 0.018) than ClearCare, and lower spontaneous blink rate (measured in picture viewing) than ClearCare (p = 0.014) and ReNu (p = 0.041). In reading, blink rate was higher for ClearCare compared to ReNu (p = 0.026) and control (p = 0.024). Visual discrimination time was longer for the control (daily disposable lens) than for Opti-Free (p = 0.007), ReNu (p = 0.009), and ClearCare (0.013) immediately before the blink. LCSs differently affected blink rate, subjective dry eye symptoms, and visual discrimination speed. Those with wetting agents led to significantly fewer eye blinks while affording better ocular comfort for contact lens wearers, compared to that without. LCSs with wetting agents also resulted in better visual performance compared to wearing daily disposable contact lenses. These presumably are because of improved tear film quality. © 2012 The College of Optometrists.

Performance of three multipurpose disinfecting solutions with a silicone hydrogel contact lens.

PubMed

García-Porta, Nery; Rico-del-Viejo, Laura; Ferreira-Neves, Helena; Peixoto-de-Matos, Sofia C; Queirós, Antonio; González-Méijome, José M

2015-01-01

To evaluate the clinical performance of a silicone hydrogel (Si-Hy) soft contact lens (CL) in combination with three different multipurpose disinfecting solutions (MPDSs). This was a prospective, randomized, single-masked, crossover, and comparative study in which 31 habitual soft CL wearers were randomly assigned to one of the three MPDSs (Synergi, COMPLETE RevitaLens, and OPTI-FREE PureMoist) for 1 month with a 1-week wash-out period between each exposure. All subjects were successfully refitted with a Si-Hy CL (Biofinity). Subjects were then scheduled for follow-up visits after 1 month of lens wear, being evaluated at 2 and 8 hours after lens insertion. Visual Analogue Scales (VAS) were used to gauge comfort rating. The tarsal conjunctiva showed a significantly different degree of lid redness between the MPDSs at the 2-hour visit (P < 0.05, Kruskal-Wallis test), being lower for COMPLETE RevitaLens compared to the other two MPDSs (Mann-Whitney U test). Furthermore, a significantly different degree of lid roughness at the 8-hour visit was seen (P < 0.05, Kruskal-Wallis test), being higher for Synergi (Mann-Whitney U test). The subjective comfort was similar with the three MPDSs. Tarsal conjunctival response should be also considered in the context of the clinical performance of MPDs at the ocular surface.

In vivo performance of a drug-eluting contact lens to treat glaucoma for a month

PubMed Central

Ciolino, Joseph B.; Stefanescu, Cristina F.; Ross, Amy E.; Salvador-Culla, Borja; Cortez, Priscila; Ford, Eden M.; Wymbs, Kate A.; Sprague, Sarah L.; Mascoop, Daniel R.; Rudina, Shireen S.; Trauger, Sunia A.; Cade, Fabiano; Kohane, Daniel S.

2013-01-01

For nearly half a century, contact lenses have been proposed as a means of ocular drug delivery, but achieving controlled drug release has been a significant challenge. We have developed a drug-eluting contact lens designed for prolonged delivery of latanoprost for the treatment of glaucoma, the leading cause of irreversible blindness worldwide. Latanoprost-eluting contact lenses were created by encapsulating latanoprost–poly(lactic-co-glycolic acid) films in methafilcon by ultraviolet light polymerization. In vitro and in vivo studies showed an early burst of drug release followed by sustained release for one month. Contact lenses containing thicker drug–polymer films demonstrated released a greater amount of drug after the initial burst. In vivo, single contact lenses were able to achieve, for at least one month, latanoprost concentrations in the aqueous humor that were comparable to those achieved with topical latanoprost solution, the current first-line treatment for glaucoma. The lenses appeared safe in cell culture and animal studies. This contact lens design can potentially be used as a treatment for glaucoma and as a platform for other ocular drug delivery applications. PMID:24094935

Proteomic analysis of protein deposits on worn daily wear silicone hydrogel contact lenses

PubMed Central

Wei, Xiaojia; Aliwarga, Yulina; Carnt, Nicole A.; Garrett, Qian; Willcox, Mark D.P.

2008-01-01

Purpose Previous studies have demonstrated deposition of tear proteins onto worn contact lenses. In this study, we used proteomic techniques to analyze the protein deposits extracted from worn daily wear silicone hydrogel contact lenses in combination with different lens care solutions. Methods Worn lenses were collected and protein deposits extracted using urea and surfactant. Protein extracts were desalted, concentrated, and then separated using one-dimensional gel electrophoresis. Individual protein components in extracts were identified using liquid chromatography combined with tandem mass spectrometry (LC-MS-MS) after trypsin digestion. Results One-dimensional gel electrophoresis revealed that lysozyme and other small proteins (around 20 kDa) were the most abundant proteins in the extracts. LC-MS-MS revealed a wide array of proteins in lens extracts with lysozyme and lipocalin 1 being the most commonly identified in deposit extracts. Conclusions Worn contact lenses deposit a wide array of proteins from tear film and other sources. Protein deposit profiles varied and were specific for each contact lens material. PMID:18989384

Steady-State Diffusion of Water through Soft-Contact LensMaterials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fornasiero, Francesco; Krull, Florian; Radke, Clayton J.

2005-01-31

Water transport through soft contact lenses (SCL) is important for acceptable performance on the human eye. Chemical-potential gradient-driven diffusion rates of water through soft-contact-lens materials are measured with an evaporation-cell technique. Water is evaporated from the bottom surface of a lens membrane by impinging air at controlled flow rate and humidity. The resulting weight loss of a water reservoir covering the top surface of the contact-lens material is recorded as a function of time. New results are reported for a conventional hydrogel material (SofLens{trademark} One Day, hilafilcon A, water content at saturation W{sub 10} = 70 weight %) and amore » silicone hydrogel material (PureVision{trademark}, balafilcon A, W{sub 10} = 36 %), with and without surface oxygen plasma treatment. Also, previously reported data for a conventional HEMA-SCL (W{sub 10} = 38 %) hydrogel are reexamined and compared with those for SofLens{trademark} One Day and PureVision{trademark} hydrogels. Measured steady-state water fluxes are largest for SofLens{trademark} One Day, followed by PureVision{trademark} and HEMA. In some cases, the measured steady-state water fluxes increase with rising relative air humidity. This increase, due to an apparent mass-transfer resistance at the surface (trapping skinning), is associated with formation of a glassy skin at the air/membrane interface when the relative humidity is below 55-75%. Steady-state water-fluxes are interpreted through an extended Maxwell-Stefan diffusion model for a mixture of species starkly different in size. Thermodynamic nonideality is considered through Flory-Rehner polymer-solution theory. Shrinking/swelling is self-consistently modeled by conservation of the total polymer mass. Fitted Maxwell-Stefan diffusivities increase significantly with water concentration in the contact lens.« less

Oxygen permeability of the pigmented material used in cosmetic daily disposable contact lenses.

PubMed

Galas, Stephen; Copper, Lenora L

2016-01-01

To evaluate the individual contributions of pigment colorant and packing solution containing polyvinyl pyrrolidone (PVP) on the oxygen permeability (Dk) of a cosmetic printed etafilcon A daily disposable contact lens packaged with PVP. The oxygen transport of a contact lens is evaluated through the central optical zone of the lens. Cosmetic printed contact lenses contain pigment colorant in the periphery or mid-periphery of the lens. Therefore, to assess the impact of cosmetic print on oxygen permeability, special lenses need to be produced that contain the colorant within the central optical zone. This technique was used to obtain multiple measurements of nonedge-corrected Dk/t of both the center pigmented lens and its nonpigmented equivalent, using a polarographic measurement described in International Organization for Standardization (ISO) 18369-4:2006(E), and the Dk derived for each measurement is corrected for edge effect. In addition, the edge-corrected Dk values of lenses made from the same monomer batch were measured. The lenses were packaged and autoclaved with and without proprietary technology which embeds PVP in the contact lens during autoclaving. The resulting Dk value of the printed lens material was then used with thickness data to generate true Dk/t profiles for a given lens power. The edge-corrected Dk of the printed etafilcon A lens with offset pigment colorant was measured to be 19.7×10 -11 (cm 2 /s) (mL O 2 /mL·mmHg) at 35°C. This was within ±20% tolerance range as specified in ISO 18369-2:2012(E) for the edge-corrected Dk of the nonpigmented etafilcon A control lens evaluated during the same session, 19.5×10 -11 (cm 2 /s) (mL O 2 /mL·mmHg). The edge-corrected Dk values of the lenses packaged with PVP (mean 20.1, standard deviation [SD] 0.3) were also within the ±20% tolerance range compared to those packaged without PVP (mean 20.0, SD 0.3). The pigment colorant and PVP embedded in the contact lens during autoclaving were not found to influence the oxygen permeability of the etafilcon A material.

Contact lens wearers' experiences while trekking in the Khumbu region/Nepal: a cross-sectional survey.

PubMed

Bauer, Irmgard L

2015-01-01

Safe contact lens wear depends on a hygiene regime and lens-appropriate wear patterns which may be compromised during travel in remote and wilderness areas. The purpose of this study was to describe the experience of contact lens wearers while trekking at high-altitude in Nepal. For this descriptive study, trekkers with contact lenses were recruited in Lukla and invited to complete an online-questionnaire on trip preparation, contact lens use, care and experiences, and possible changes for future travel. Quantitative data were analysed using SurveyMonkey; content analysis applied to qualitative responses. The majority of the 158 participants (124; 78.48%) reported no problems with their lenses (daily disposables, soft lenses, extended-wear lenses, hard/rigid lenses) during their stay although dry air, dust, wind, cold temperatures, and difficult hygiene maintenance were challenging. Freezing lenses and freezing solutions were additional challenges. Thirty-four (21.52%) experienced a variety of problems. Improvements were requested from manufacturers. Lodges should provide better access to clean water, mirrors and lighting. Almost 60% of participants had not sought any pre-travel health advice. Remote and wilderness areas provide a challenge for appropriate contact lens wear and care. The decision between the potential risk of infection due to touching lenses (daily disposables, soft/hard lenses) and the potential risk of corneal erosion (extended-wear lenses) needs to be made in pre-travel consultations. Travel health professionals and travel agencies should remind CL-wearing trekkers to carefully assess their wear and care routine to accommodate potentially challenging conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Pupil size stability of the cubic phase mask solution for presbyopia

NASA Astrophysics Data System (ADS)

Almaguer, Citlalli; Acosta, Eva; Arines, Justo

2018-01-01

Presbyopia correction involves different types of studies such as lens design, clinical study, and the development of objective metrics, such as the visual Strehl ratio. Different contact lens designs have been proposed for presbyopia correction, but performance depends on pupil diameter. We will analyze the potential use of a nonsymmetrical element, a cubic phase mask (CPM) solution, to develop a contact or intraocular lens whose performance is nearly insensitive to changes in pupil diameter. We will show the through focus optical transfer function of the proposed element for different pupil diameters ranging from 3 to 7 mm. Additionally, we will show the images obtained through computation and experiment for a group of eye charts with different visual acuities. Our results show that a CPM shaped as 7.07 μm*(Z33-Z3-3)-0.9 μm Z20 is a good solution for a range of clear vision with a visual acuity of at least 0.1 logMar from 0.4 to 6 m for pupil diameters in the 3- to 7-mm range. Our results appear to be a good starting point for further development and study of this kind of CPM solution for presbyopia.

Ethylene oxide-block-butylene oxide copolymer uptake by silicone hydrogel contact lens materials

NASA Astrophysics Data System (ADS)

Huo, Yuchen; Ketelson, Howard; Perry, Scott S.

2013-05-01

Four major types of silicone hydrogel contact lens material have been investigated following treatments in aqueous solutions containing poly(ethylene oxide) and poly(butylenes oxide) block copolymer (EO-BO). The extent of lens surface modification by EO-BO and the degree of bulk uptake were studied using X-ray photoelectron spectroscopy (XPS) and ultra-performance liquid chromatography (UPLC), respectively. The experimental results suggest that different interaction models exist for the lenses, highlighting the influence of both surface and bulk composition, which greatly differs between the lenses examined. Specifically, lenses with hydrophilic surface treatments, i.e., PureVision® (balafilcon A) and O2OPTIX (lotrafilcon B), demonstrated strong evidence of preferential surface adsorption within the near-surface region. In comparison, surface adsorption on ACUVUE® Oasys® (senofilcon A) and Biofinity® (comfilcon A) was limited. As for bulk absorption, the amount of EO-BO uptake was the greatest for balafilcon A and comfilcon A, and least for lotrafilcon B. These findings confirm the presence of molecular concentration gradients within the silicone hydrogel lenses following exposure to EO-BO solutions, with the nature of such concentration gradients found to be lens-specific. Together, the results suggest opportunities for compositional modifications of lenses for improved performance via solution treatments containing surface-active agents.

Controlled delivery of pirfenidone through vitamin E-loaded contact lens ameliorates corneal inflammation.

PubMed

Dixon, Phillip; Ghosh, Tanushri; Mondal, Kalyani; Konar, Aditya; Chauhan, Anuj; Hazra, Sarbani

2018-06-01

Chemical injury by alkali burn is a major cause of corneal blindness in the clinical setting. Current management advocates multiple therapies aimed to prevent inflammation, initiate quick re-epithelialization, arrest the fibrosis, and avoid dry eye and pain by using bandage contact lenses. We hypothesized sustained delivery of the anti-inflammatory, antifibrotic drug pirfenidone through vitamin E-loaded contact lenses as a logical single approach to counter the pathology involved. Vitamin E particles were created in situ in commercial silicon hydrogel contact lenses by soaking the lenses in a vitamin E-ethanol solution. The vitamin E-laden lenses were then placed into pirfenidone-saline solution to load the drug into the lens. The contact lenses were evaluated by both in vitro and in vivo means. For in vitro, lenses were placed into 3 mL of saline solution. The concentration of pirfenidone released was measured by UV-vis spectrophotometry. The contact lenses were implanted in rabbit eyes following the alkali burn; the drug availability in the aqueous humor was evaluated by HPLC at various time points 10 min, 30 min, 2 h, and 3 h; and gene expression of inflammatory cytokines IL-1β, TNF-α, and TGF-β1 was evaluated in the cornea at the end of the study period. In another group of rabbits inflicted with alkali injury, the corneas were graded after 7 days of contact lens implantation with and without pirfenidone. A mathematical model was developed for delivery of the drug to the cornea and aqueous humor after a contact lens is inserted in the eye. The model was validated with experimental data and used to determine the bioavailability both for contact lenses and eye drops. In vitro release of unmodified commercial contact lenses saw a release time of approximately 20 min, with a partition coefficient of 2.68 ± 0.06. The release of pirfenidone from 20% vitamin E-loaded lenses saw a release time of approximately 80 min, with a partition coefficient of 4.20 ±  0.04. In vivo, the drug was available in the aqueous humor for up to 3 h. Gene expression of inflammatory cytokine IL-β1 and profibrotic growth factor TGF-β1 was significantly suppressed in corneas treated with pirfenidone contact lenses. A week after the alkali burn, the eyes with pirfenidone contact lenses showed significant improvement in corneal haze in comparison to the control eyes. About 50% of the drug loaded in the lens reached the aqueous humor compared to 1.3% with eye drops. Vitamin E-loaded contact lenses serve as a suitable platform for delivery of pirfenidone following alkali burn in rabbit eyes; positive pre-clinical outcome identifies it as promising therapy for addressing corneal inflammation and fibrosis. The bioavailability is about 40-fold higher for contact lenses compared to that for eye drops.

The effect of contact lens materials on disinfection activity of polyquaternium-1 and myristamidopropyl dimethylamine multipurpose solution against Staphylococcus aureus.

PubMed

Shoff, Megan E; Lucas, Anne D; Phillips, K Scott; Brown, Jennifer N; Hitchins, Victoria M; Eydelman, Malvina B

2012-11-01

This study examined the interaction of seven different lens materials with a multipurpose solution (MPS) containing the disinfectants polyquaternium-1 (0.001%) and myristamidopropyl dimethylamine (0.0005%). The objective of this study was to determine whether the different lens materials affect the concentration of a disinfectant in this commercially available MPS and the efficacy of the disinfectant against Staphylococcus aureus. Silicone hydrogel lenses (galyfilcon A, senofilcon A, comfilcon A, enfilcon A, balafilcon A, and lotrafilcon B) and a conventional hydrogel lens (etafilcon A) were soaked in polypropylene lens cases filled with commercially available MPS containing 0.001% polyquaternium-1 and 0.0005% myristamidopropyl dimethylamine for 6, 12, 24, 72, and 168 hours. Empty lens cases were also filled with MPS. After each time point, solutions from cases containing the seven types of lenses and controls were assayed for activity against S. aureus according to International Standards Organization 14729 standard with modifications. Test solutions were analyzed for polyquaternium-1 and myristamidopropyl dimethylamine concentration at each time point. The concentration of polyquaternium-1 and myristamidopropyl dimethylamine remaining in the lens cases was reduced only slightly over time. Storage with the lenses did not adversely affect biocidal efficacy of the solution, and in some cases, it was significantly better (P=0.0029). The efficacy of this polyquaternium-1 and myristamidopropyl dimethylamine MPS to kill S. aureus was not adversely affected by the presence of lens materials soaking in the cases. Thus, current methods for performing solution antimicrobial testing should be reevaluated.

Extended Ciprofloxacin Release Using Vitamin E Diffusion Barrier From Commercial Silicone-Based Soft Contact Lenses.

PubMed

Shayani Rad, Maryam; Mohajeri, Seyed Ahmad

2017-03-01

Ciprofloxacin (Cipro) is an antibiotic, widely used in form of ophthalmic drops (0.3%) for the treatment of eye infections. In this study, vitamin E was used as a hydrophobic barrier to improve and prolong the amount and time of Cipro release from silicone-based soft contact lenses. Three different commercial contact lenses (Air Optix, Biofinity, and Acuvue Oasys) were soaked in vitamin E solutions (0.1 and 0.2 g/mL). The effect of vitamin E on Cipro loading amount and drug releasing profile was evaluated in artificial tear. Swelling properties and diameter changes of the lenses were also investigated in aqueous media in presence and absence of vitamin E. The data indicated that vitamin E, as a hydrophobic barrier, significantly decreased the water content of silicone-based soft contact lenses. After vitamin E loading, a 5% to 18% increase was observed in lens diameter in the hydrated state, whereas the lens diameter increased by 11% to 23% in the dry state. In all commercial lenses, vitamin E loading in a 0.2-g/mL solution caused a 27.94% to 37.08% increase in Cipro binding. The results indicated that applying vitamin E loading solutions, with 0.1 and 0.2 g/mL concentrations, could effectively enhance Cipro release time from 2 hr (in a pure non-vitamin E-loaded lens) to 14 to 17 and 30 to 33 days, respectively. These values showed an increase by a factor of 168 to 204 and 360 to 396 in Cipro release time after using vitamin E loading solutions with 0.1 and 0.2 g/mL concentrations, respectively, compared with pure non-vitamin E-loaded soft contact lenses. This study indicated that vitamin E acts as an effective hydrophobic barrier, in increasing the Cipro loading capacity of silicone-based contact lenses and prolonging the drug release into the artificial tear.

Performance of Three Multipurpose Disinfecting Solutions with a Silicone Hydrogel Contact Lens

PubMed Central

García-Porta, Nery; Rico-del-Viejo, Laura; Ferreira-Neves, Helena; Peixoto-de-Matos, Sofia C.; Queirós, Antonio; González-Méijome, José M.

2015-01-01

Purpose. To evaluate the clinical performance of a silicone hydrogel (Si-Hy) soft contact lens (CL) in combination with three different multipurpose disinfecting solutions (MPDSs). Methods. This was a prospective, randomized, single-masked, crossover, and comparative study in which 31 habitual soft CL wearers were randomly assigned to one of the three MPDSs (Synergi, COMPLETE RevitaLens, and OPTI-FREE PureMoist) for 1 month with a 1-week wash-out period between each exposure. All subjects were successfully refitted with a Si-Hy CL (Biofinity). Subjects were then scheduled for follow-up visits after 1 month of lens wear, being evaluated at 2 and 8 hours after lens insertion. Visual Analogue Scales (VAS) were used to gauge comfort rating. Results. The tarsal conjunctiva showed a significantly different degree of lid redness between the MPDSs at the 2-hour visit (P < 0.05, Kruskal-Wallis test), being lower for COMPLETE RevitaLens compared to the other two MPDSs (Mann-Whitney U test). Furthermore, a significantly different degree of lid roughness at the 8-hour visit was seen (P < 0.05, Kruskal-Wallis test), being higher for Synergi (Mann-Whitney U test). The subjective comfort was similar with the three MPDSs. Conclusion. Tarsal conjunctival response should be also considered in the context of the clinical performance of MPDs at the ocular surface. PMID:25918703

On the the Contact Lens Problem: Modeling Rigid and Elastic Beams on Thin Films

NASA Astrophysics Data System (ADS)

Trinh, Philippe; Wilson, Stephen; Stone, Howard

2011-11-01

Generally, contact lenses are prescribed by the practitioner to fit each individual patient's eye, but these fitting-philosophies are based on empirical studies and a certain degree of trial-and-error. A badly fitted lens can cause a range of afflictions, which varies from mild dry-eye-discomfort, to more serious corneal diseases. Thus, at this heart of this problem, is the question of how a rigid or elastic plate interacts with the free-surface of a thin viscous film. In this talk, we present several mathematical models for the study of these plate-and-fluid problems. Asymptotic and numerical results are described, and we explain the role of elasticity, surface tension, viscosity, and pressure in determining the equilibrium solutions. Finally, we discuss the implications of our work on the contact lens problem, as well as on other coating processes which involve elastic substrates.

Controlled Release of Multiple Therapeutics from Silicone Hydrogel Contact Lenses.

PubMed

White, Charles James; DiPasquale, Stephen Anthony; Byrne, Mark Edward

2016-04-01

The majority of contact lens wearers experience a significant level of ocular discomfort associated with lens wear, often within hours of wear, related to dry lenses, inflammation, protein adhesion to the lens surface, etc. Application of controlled drug release techniques has focused on the incorporation and/or release of a single comfort molecule from a lens including high molecular weight comfort agents or pharmaceutical agents. Previous studies have sought to mitigate the occurrence of only single propagators of discomfort. Clinical studies with eye drop solutions have shown that a mixture of diverse comfort agents selected to address multiple propagators of discomfort provide the greatest and longest lasting sensations of comfort for the patient. In this paper, multiple propagators of discomfort are addressed through the simultaneous release of four molecules from a novel contact lens to ensure high level of lens wear comfort. Silicone hydrogel contact lenses were engineered via molecular imprinting strategies to simultaneously release up to four template molecules including hydropropyl methylcellulose (HPMC), trehalose, ibuprofen, and prednisolone. By adjusting the ratio of functional monomer to comfort molecule, a high level of control was demonstrated over the release rate. HPMC, trehalose, ibuprofen, and prednisolone were released at therapeutically relevant concentrations with varying rates from a single lens. The results indicate use as daily disposable lenses for single day release or extended-wear lenses with multiple day release. Imprinted lenses are expected to lead to higher efficacy for patients compared to topical eye drops by improving compliance and mitigating concentration peaks and valleys associated with multiple drops.

Controlled Release of Multiple Therapeutics from Silicone Hydrogel Contact Lenses

PubMed Central

White, Charles J.; DiPasquale, Stephen A.; Byrne, Mark E.

2016-01-01

Purpose The majority of contact lens wearers experience a significant level of ocular discomfort associated with lens wear, often within hours of wear, related to dry lenses, inflammation, protein adhesion to the lens surface, etc. Application of controlled drug release techniques has focused on the incorporation and/or release of a single comfort molecule from a lens including high molecular weight comfort agents or pharmaceutical agents. Previous studies have sought to mitigate the occurrence of only single propagators of discomfort. Clinical studies with eye drop solutions have shown that a mixture of diverse comfort agents selected to address multiple propagators of discomfort provide the greatest and longest lasting sensations of comfort for the patient. In this paper, multiple propagators of discomfort are addressed through the simultaneous release of four molecules from a novel contact lens to ensure high level of lens wear comfort. Methods Silicone hydrogel contact lenses were engineered via molecular imprinting strategies to simultaneously release up to four template molecules including hydropropyl methylcellulose (HPMC), trehalose, ibuprofen, and prednisolone. Results By adjusting the ratio of functional monomer to comfort molecule, a high level of control was demonstrated over the release rate. HPMC, trehalose, ibuprofen, and prednisolone were released at therapeutically relevant concentrations with varying rates from a single lens. Conclusions The results indicate use as daily disposable lenses for single day release or extended-wear lenses with multiple day release. Imprinted lenses are expected to lead to higher efficacy for patients compared to topical eye drops by improving compliance and mitigating concentration peaks and valleys associated with multiple drops. PMID:26945177

Oxygen permeability of the pigmented material used in cosmetic daily disposable contact lenses

PubMed Central

Galas, Stephen; Copper, Lenora L

2016-01-01

Purpose To evaluate the individual contributions of pigment colorant and packing solution containing polyvinyl pyrrolidone (PVP) on the oxygen permeability (Dk) of a cosmetic printed etafilcon A daily disposable contact lens packaged with PVP. Method The oxygen transport of a contact lens is evaluated through the central optical zone of the lens. Cosmetic printed contact lenses contain pigment colorant in the periphery or mid-periphery of the lens. Therefore, to assess the impact of cosmetic print on oxygen permeability, special lenses need to be produced that contain the colorant within the central optical zone. This technique was used to obtain multiple measurements of nonedge-corrected Dk/t of both the center pigmented lens and its nonpigmented equivalent, using a polarographic measurement described in International Organization for Standardization (ISO) 18369-4:2006(E), and the Dk derived for each measurement is corrected for edge effect. In addition, the edge-corrected Dk values of lenses made from the same monomer batch were measured. The lenses were packaged and autoclaved with and without proprietary technology which embeds PVP in the contact lens during autoclaving. The resulting Dk value of the printed lens material was then used with thickness data to generate true Dk/t profiles for a given lens power. Results The edge-corrected Dk of the printed etafilcon A lens with offset pigment colorant was measured to be 19.7×10−11 (cm2/s) (mL O2/mL·mmHg) at 35°C. This was within ±20% tolerance range as specified in ISO 18369-2:2012(E) for the edge-corrected Dk of the nonpigmented etafilcon A control lens evaluated during the same session, 19.5×10−11 (cm2/s) (mL O2/mL·mmHg). The edge-corrected Dk values of the lenses packaged with PVP (mean 20.1, standard deviation [SD] 0.3) were also within the ±20% tolerance range compared to those packaged without PVP (mean 20.0, SD 0.3). Conclusion The pigment colorant and PVP embedded in the contact lens during autoclaving were not found to influence the oxygen permeability of the etafilcon A material. PMID:28003735

Review on prevention of bacterial adhesion on contact lens using plasma treatment

NASA Astrophysics Data System (ADS)

Ramli, N. A. H.; Zaaba, S. K.; Mustaffa, M. T.; Zakaria, A.; Shahriman A., B.

2017-03-01

Many researches had been conducted to enhance the properties of contact lens. Most of the research conducted discussed on the factors that affect the adhesion process to contact lenses, rate of contact lens contamination, and type of microbe that adhere on the contact lens surface and contact lens casing. Studies on the proposed strategies or technology that can be used to slower down the formation of bacteria on contact lens are being explored. New technologies or strategies to prevent or slow down the adhesion of bacteria on contact lens have become a priority in this area. This review paper covers two main aspects, namely factor that affect the bacteria adhesion on contact lens and also the introduction of plasma treatment as a potential method for contact lens treatment.

The safety and efficacy of contact lens wear in the industrial and chemical workplace.

PubMed

Tyhurst, Keith; McNett, Ryan; Bennett, Edward

2007-11-01

The use and safety of contact lenses in the industrial and chemical workplace has often been questioned since the 1960s because of many unconfirmed reports of ocular injury resulting from contact lens wear. Because of these urban legends, contact lens wear has been banned or wearers have been required to wear additional personal protective equipment (PPE) not required of non-contact lens wearers. Literature review via Medline and Google search. Research has shown that contact lenses typically provide protective benefits that decrease the severity of ocular injury and improve worker performance. While contact lens wear contraindications do exist, in most cases, and with proper precautions, contact lens wear is still possible. Industrial and chemical companies need to establish written contact lens use policies based on current studies that have shown the safety of workplace contact lens wear when combined with the same PPE required of non-contact lens wearers. Practitioners need to discuss, with their contact lens patients, the additional responsibilities required to maintain proper lens hygiene and proper PPE in the workplace.

Effects of silicone hydrogel contact lens wear on ocular surface sensitivity to tactile, pneumatic mechanical, and chemical stimulation.

PubMed

Situ, Ping; Simpson, Trefford L; Jones, Lyndon W; Fonn, Desmond

2010-12-01

To determine the effects of silicone hydrogel lens wear and lens-solution interactions on ocular surface sensitivity. Forty-eight adapted lens wearers completed the study, which comprised two phases. Phase 1 included habitual lens wear, no lens wear (7 ± 3 days), and balafilcon A lenses (PV; PureVision; Bausch & Lomb, Rochester, NY) with a hydrogen peroxide-based regimen for 2 weeks; phase 2 included wear of PV with the use of a multipurpose solution containing either polyhexamethylene-biguanide (PHMB) or Polyquad/Aldox (Alcon Laboratories, Fort Worth, TX) preservative, each for 1 week, with a 2-week washout period between solutions. Tactile and pneumatic (mechanical and chemical) stimuli were delivered, and thresholds were determined by Cochet-Bonnet (Luneau Ophthalmologie, Chartres, France) and Belmonte (Cooperative Research Centre for Eye Research and Technology, Sydney, NSW, Australia) pneumatic esthesiometers, respectively. Corneal and conjunctival thresholds and staining scores were assessed at baseline, after 2 and 8 hours of lens wear on day 1 and at the end of each wearing cycle (2 hours). In phase 1, compared to the no-lens baseline, corneal tactile thresholds increased at the 1-day, 8-hour and the 2-week visits (P < 0.05), whereas conjunctival mechanical thresholds decreased at the 1-day, 2-hour and the 2-week visits (P < 0.05). In phase 2, the chemical thresholds were lower with PHMB-preserved solution compared with the Polyquad/Aldox system at the 1-day, 2-hour and the 1-week visits (P < 0.05). Staining scores correlated inversely with conjunctival chemical thresholds (all P < 0.05). Ocular surface sensitivity changed in adapted lens wearers, when lenses were refit after a no-lens interval and during lens wear with different care regimens. The corneal staining that was observed with certain lens-solution combinations was accompanied by sensory alteration of the ocular surface-that is, higher levels of staining correlated with increased conjunctival chemical sensitivity. (ClinicalTrials.gov number, NCT00455455.).

The TFOS International Workshop on Contact Lens Discomfort: Report of the Subcommittee on Neurobiology

PubMed Central

Stapleton, Fiona; Marfurt, Carl; Golebiowski, Blanka; Rosenblatt, Mark; Bereiter, David; Begley, Carolyn; Dartt, Darlene; Gallar, Juana; Belmonte, Carlos; Hamrah, Pedram; Willcox, Mark

2013-01-01

This report characterizes the neurobiology of the ocular surface and highlights relevant mechanisms that may underpin contact lens–related discomfort. While there is limited evidence for the mechanisms involved in contact lens–related discomfort, neurobiological mechanisms in dry eye disease, the inflammatory pathway, the effect of hyperosmolarity on ocular surface nociceptors, and subsequent sensory processing of ocular pain and discomfort have been at least partly elucidated and are presented herein to provide insight in this new arena. The stimulus to the ocular surface from a contact lens is likely to be complex and multifactorial, including components of osmolarity, solution effects, desiccation, thermal effects, inflammation, friction, and mechanical stimulation. Sensory input will arise from stimulation of the lid margin, palpebral and bulbar conjunctiva, and the cornea. PMID:24058137

Risk factors for microbial bioburden during daily wear of silicone hydrogel contact lenses.

PubMed

Jiang, Ying; Jacobs, Michael; Bajaksouzian, Saralee; Foster, Altreisha N; Debanne, Sara M; Bielefeld, Roger; Garvey, Matt; Raghupathy, Sangeetha; Kern, Jami; Szczotka-Flynn, Loretta B

2014-05-01

To assess risk factors associated with substantial microbial bioburden of lids, conjunctivae, contact lenses, and storage cases during daily wear of silicone hydrogel contact lenses. Two hundred eighteen patients were fit to lotrafilcon A lenses, randomized to use either a multipurpose solution or a hydrogen peroxide care system, and followed up for 1 year. Lenses, lens transport saline, lids, conjunctivae, and storage cases were cultured and considered to have substantial microbial bioburden when they harbored high levels of commensal or pathogenic organisms. Univariate and multivariate logistic regression analyses were conducted to examine which demographic covariates were associated with significant bioburden at each location while controlling for solution use. In multivariate analyses, smoking trended toward an association with lens bioburden (odds ratio [OR]=2.15, 95% confidence interval [CI]: 0.95-4.88). Clerical occupations were found to be associated with more frequent overall storage case contamination (OR=3.51, 95% CI: 1.15-10.70) and, specifically, higher gram-positive storage case contamination (OR=5.57, 95% CI: 1.82-17.06). The peroxide system was associated with more frequent storage case contamination (OR=7.6, 95% CI: 3.79-15.19). Coagulase-negative staphylococci (CNS) were the most frequently cultured organisms within storage cases, and in multivariate analyses, CNS were more frequently found in storage cases of peroxide users (OR=6.12, 95% CI: 2.91-13.09). Clerical occupations were associated with increased microbial bioburden of storage cases during daily wear of silicone hydrogel lenses. Smoking may increase the risk of lens contamination. Storage cases are most frequently contaminated with normal skin flora, and peroxide cases were associated with more frequent contamination. However, the solution type was not associated with lid or lens contamination nor with corneal infiltrative events in this study.

Contact lens deposits, adverse responses, and clinical ocular surface parameters.

PubMed

Zhao, Zhenjun; Naduvilath, Thomas; Flanagan, Judith L; Carnt, Nicole A; Wei, Xiaojia; Diec, Jennie; Evans, Vicki; Willcox, Mark D P

2010-09-01

To correlate clinical responses during contact lens wear with the amount of protein or cholesterol extracted from lenses after wear. Clinical parameters, including adverse response rates and corneal staining, and symptomatology rating during lens wear were collected from a series of clinical tests comprising four different silicone hydrogel lenses with four different multipurpose solutions. To test for correlates, the amount of total protein or cholesterol extracted from lenses after daily wear were compared statistically to clinical parameters. The amount of protein (p = 0.008) or cholesterol (p = 0.01) extracted from lenses was higher for those subjects who showed solution-induced corneal staining. Amount of protein extracted was correlated (p < 0.01) with conjunctival staining (R = -0.23), lens front surface wetting (r = 0.14), and lens fit tightness (R = -0.20). These clinical parameters accounted for 48% of lens protein deposition. The amount of cholesterol extracted from lenses was much more weakly associated with clinical variables. Amount of protein or cholesterol extracted from lenses was not associated with the production of any corneal infiltrative or mechanical adverse event during wear and was only very weakly correlated with insertion comfort of lenses. These results suggest that there may be no physiologically relevant consequence of cholesterol depositing on silicone hydrogel lenses. The amount of protein that deposits onto silicone hydrogel lenses during wear may have more affect on lens performance on-eye. However, the correlations were generally small and may still not indicate any causative relevant physiological response. Further work is required to determine whether there is any direct causative effect to support these correlative findings.

Clinical evaluation of long-term users of two contact lens care preservative systems.

PubMed

Young, Graeme; Keir, Nancy; Hunt, Chris; Woods, Craig A

2009-03-01

To clinically evaluate long-term users of two different contact lens care preservative systems and to investigate whether prolonged use is associated with an increase in the prevalence of dry eye. Eighty-nine wearers of group IV hydrogel or silicone hydrogel lenses participated in this one-visit, investigator-masked study. Subjects were required to have consistently used a polyhexamethylene biguanide (PHMB) or polyquaternium-1 (PQT) based solution for 2 years. Consistent use was defined as 80% for the past 2 years and 100% for the past year. Clinical assessments included: average and comfortable wear time; overall and end-of-day comfort; signs of dryness, discomfort, burning or stinging, grittiness or scratchiness and visual changes; non-invasive and fluorescein break-up-time; pre-ocular tear film lipids, tear meniscus height, Schirmer and fluorescein clearance tests; limbal and bulbar hyperemia; palpebral roughness; corneal and conjunctival staining; lens front surface wetting; and lens film deposits. Significantly more grittiness or scratchiness was reported by subjects using a PHMB-containing system (67% vs. 44%; P = 0.02). Palpebral roughness and hyperemia were significantly greater in the PHMB group wearing group IV lenses (P = 0.01 and P = 0.05, respectively). Corneal staining was significantly higher in the PHMB users in all four peripheral sectors (P < 0.01). Nasal and temporal conjunctival staining was also significantly higher for users of PHMB-containing systems (P < 0.05). Front surface lens wettability was significantly better for group IV PQT users compared to PHMB users (P = 0.008), with 84% vs. 72%, respectively, with lenses graded by the investigator as having "good" or "excellent" wettability. Significantly higher levels of lens front surface film deposits were noted with PHMB users (P = 0.007), with 58% of group IV lenses treated with PHMB compared with 38% of group IV lenses treated with PQT showing some lens front surface film deposition. No significant differences between the two preservative system groups were noted for the range of dry eye evaluations nor the remaining clinical assessments. Differences in both ocular and lens characteristic were observed between long-term users of two preservative systems used in many contact lens multi-purpose solutions. The findings from this study did not support the hypothesis that prolonged use of PHMB-containing solutions leads to dry eye. Additional studies including a larger sample size and perhaps longer use of the systems could help to further elucidate differences in clinical performance between systems.

16 CFR 315.6 - Expiration of contact lens prescriptions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Expiration of contact lens prescriptions. 315.6 Section 315.6 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS UNDER SPECIFIC ACTS OF CONGRESS CONTACT LENS RULE § 315.6 Expiration of contact lens prescriptions. (a) In general. A contact lens...

Effect of contact lens on optical coherence tomography imaging of rodent retina.

PubMed

Liu, Xiaojing; Wang, Chia-Hao; Dai, Cuixia; Camesa, Adam; Zhang, Hao F; Jiao, Shuliang

2013-12-01

To evaluate the effect of powerless contact lens on improving the quality of optical coherence tomography imaging of rodent retina. A spectral-domain optical coherence tomography (SD-OCT) system was built for in vivo imaging of rodent retina. The calibrated depth resolution of the system was 3 µm in tissue. A commercial powerless contact lens for rat eye was tested in the experiments. For each rat eye, the retina was imaged in vivo sequentially first without wearing contact lens and then with wearing contact lens. The lateral resolution and signal-to-noise ratio of the OCT images with and without contact lens were compared to evaluate the improvement of image quality. The fundus images generated from the measured 3D OCT datasets with contact lens showed sharper retinal blood vessels than those without contact lens. The contrast of the retinal blood vessels was also significantly enhanced in the OCT fundus images with contact lens. As high as 10 dB improvements in SNR was observed for OCT images with contact lens compared to the images of the same retinal area without contact lens. We have demonstrated that the use of powerless contact lens on rat eye can significantly improve OCT image quality of rodent retina, which is a benefit in addition to preventing cataract formation. We believe the improvement in image quality is the result of partial compensation of the optical aberrations of the rodent eye by the contact lens.

Kinetics of Platinum-Catalyzed Decomposition of Hydrogen Peroxide

NASA Astrophysics Data System (ADS)

Vetter, Tiffany A.; Colombo, D. Philip, Jr.

2003-07-01

CIBA Vision Corporation markets a contact lens cleaning system that consists of an AOSEPT disinfectant solution and an AOSEPT lens cup. The disinfectant is a buffered 3.0% m/v hydrogen peroxide solution and the cup includes a platinum-coated AOSEPT disc. The hydrogen peroxide disinfects by killing bacteria, fungi, and viruses found on the contact lenses. Because the concentration of hydrogen peroxide needed to disinfect is irritating to eyes, the hydrogen peroxide needs to be neutralized, or decomposed, before the contact lenses can be used again. A general chemistry experiment is described where the kinetics of the catalyzed decomposition of the hydrogen peroxide are studied by measuring the amount of oxygen generated as a function of time. The order of the reaction with respect to the hydrogen peroxide, the rate constant, and the energy of activation are determined. The integrated rate law is used to determine the time required to decompose the hydrogen peroxide to a concentration that is safe for eyes.

Inner layer-embedded contact lenses for pH-triggered controlled ocular drug delivery.

PubMed

Zhu, Qiang; Liu, Chang; Sun, Zheng; Zhang, Xiaofei; Liang, Ning; Mao, Shirui

2018-07-01

Contact lenses (CLs) are ideally suited for controlled ocular drug delivery, but are limited by short release duration, poor storage stability and low drug loading. In this study, we present a novel inner layer-embedded contact lens capable of pH-triggered extended ocular drug delivery with good storage stability. Blend film of ethyl cellulose and Eudragit S100 was used as the inner layer, while pHEMA hydrogel was used as outer layer to fabricate inner layer-embedded contact lens. Using diclofenac sodium(DS) as a drug model, influence of polymer ratio in the blend film, EC viscosity, drug/polymer ratio, inner layer thickness and outlayer thickness of pHEMA hydrogel on drug release behavior was studied and optimized for daily use. The pH-triggered drug eluting pattern enables the inner layer-embedded contact lens being stored in phosphate buffer solution pH 6.8 with ignorable drug loss and negligible changes in drug release pattern. In vivo pharmacokinetic study in rabbits showed sustained drug release for over 24 h in tear fluid, indicating significant improvement in drug corneal residence time. A level A IVIVC was established between in vitro drug release and in vivo drug concentration in tear fluid. In conclusion, this inner layer embedded contact lens design could be used as a platform for extended ocular drug delivery with translational potential for both anterior and posterior ocular diseases therapy. Copyright © 2018 Elsevier B.V. All rights reserved.

A novel phosphorylcholine-coated contact lens for extended wear use.

PubMed

Court, J L; Redman, R P; Wang, J H; Leppard, S W; Obyrne, V J; Small, S A; Lewis, A L; Jones, S A; Stratford, P W

2001-12-01

The preparation and characterisation of a new phosphorylcholine (PC)-coated silicone hydrogel contact lens for use in extended wear is described. The Michael-type addition of amines to acrylates forms the basis of the synthesis of a novel silicone-based macromer with hydrophilic functionality. It is demonstrated that this macromer can be combined with other silicone-based monomers, hydrophilic monomers and crosslinker to produce a contact lenses formulation. Examples of lenses with water contents of 33% and 46% are illustrated and their properties compared to other commercially available lenses. Materials with comparatively low modulus (<0.3 MPa) and adequate tear strength (>2-4MPa) with excellent elongation to break (>200%) can be obtained using this technology. In addition to the mechanical aspects. both the oxygen and solute permeabilities of the material can be controlled by the hydrophilic: hydrophobic monomer balance in the formulation. to obtain materials with attributes suitable for extended wear use. The PC coating is achieved by means of an in-mould coating (IMC) technique that produces a uniform and stable surface as determined by staining and XPS. The coating imparts both improved lens wettability (advancing contact angle of approximately 50 with virtually no hysteresis) and lower protein adsorption relative to the uncoated lens.

16 CFR 315.3 - Availability of contact lens prescriptions to patients.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Availability of contact lens prescriptions... SPECIFIC ACTS OF CONGRESS CONTACT LENS RULE § 315.3 Availability of contact lens prescriptions to patients. (a) In general. When a prescriber completes a contact lens fitting, the prescriber: (1) Whether or...

16 CFR 315.3 - Availability of contact lens prescriptions to patients.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Availability of contact lens prescriptions... SPECIFIC ACTS OF CONGRESS CONTACT LENS RULE § 315.3 Availability of contact lens prescriptions to patients. (a) In general. When a prescriber completes a contact lens fitting, the prescriber: (1) Whether or...

Silicone hydrogel contact lenses surface promote Acanthamoeba castellanii trophozoites adherence: qualitative and quantitative analysis.

PubMed

Omaña-Molina, Maritza A; González-Robles, Arturo; Salazar-Villatoro, Lizbeth; Bernal-Escobar, Alexander; Durán-Díaz, Angel; Méndez-Cruz, Adolfo René; Martínez-Palomo, Adolfo

2014-05-01

To describe the adhesion properties of Acanthamoeba castellanii trophozoites to silicone hydrogel contact lenses of first generation (lotrafilcon A), second generation (galyfilcon A), and third generation (comfilcon A) and correlate the results with their specific surface characteristics, time of interaction, and suspension media. Qualitative and quantitative assessments of the adhesion of 200 trophozoites of A. castellanii on contact lenses in culture medium (Bacto Casitone) and isotonic saline (IS) at different time points (15 minutes and 6 hours) were determined. By scanning electron microscopy, A. castellanii trophozoites were observed firmly adhered to the surface of hydrogel lenses after 15 minutes of interaction. The surface of lotrafilcon A lenses on which amoebae adhere better (16.4±10.2 amoebae/lens section) is rough and folded, which increases the contact surface with trophozoites, allowing acanthopodia to attach firmly. Contrarily, galyfilcon A lenses have a smoother surface, and lower numbers of amoebae were observed adhered to these lenses (4.7±2.9 amoebae/lens section). Even fewer amoebae adhered to the smoother surface of the comfilcon A lens (2.2±1.7 amoebae/lens section). Trophozoites showed similar behavior in both Bacto Casitone medium and IS. A rough surface may contribute to better adhesion of amoebae to silicone hydrogel lenses. Although a reduced numbers of trophozoites adhered to smooth lenses, trophozoites are a risk factor for amoebic keratitis. Isotonic saline facilitated trophozoite survival, suggesting that homemade saline solutions may contribute to the persistence of trophozoites, especially when there is no proper hygiene regimen used with the contact lens cases.

The Impact of Inoculation Parameters on the Pathogenesis of Contact Lens–Related Infectious Keratitis

PubMed Central

Tam, Connie; Mun, James J.; Evans, David J.

2010-01-01

Purpose. Contact lens wear predisposes to Pseudomonas aeruginosa keratitis, but the mechanisms involved remain unclear. An in vivo model was used to study lens inoculation conditions enabling disease. Methods. Custom-made hydrogel contact lenses were fitted to rats after incubation in P. aeruginosa approximately 1011 cfu/mL (3 hours) or approximately 103 cfu/mL (24 hours). Another group was inadvertently inoculated with a suction pen previously used with high inocula, but rinsed in ethanol and stored dry (6 months). Some corneas were tissue paper–blotted to cause fluorescein staining before lens fitting. Contralateral eyes were untreated. Twenty-four hours after disease detection, lenses were transferred to naive rats or examined by confocal microscopy before homogenization to quantify viable bacteria. After lens removal, corneas were washed to collect nonadherent bacteria and were analyzed by immunohistochemistry. Results. All eyes challenged with unworn contaminated lenses developed keratitis after approximately 7 to 10 days. Disease delay and severity were unaffected by inoculum parameters or tissue blotting but occurred sooner with lenses transferred from infected eyes (∼2 days). Worn lenses and corneal washes contained infecting bacteria. Posterior, not anterior, lens surfaces harbored P. aeruginosa biofilms that penetrated the lens matrix. Diseased corneas showed an infiltration of phagocytes and T-lymphocytes. Conclusions. P. aeruginosa induces keratitis in this lens-wearing model after a single inoculation. Delayed disease onset was interesting considering the greater keratitis risk during extended wear. Infection did not require the disruption of corneal barrier function before lens wear and occurred without exposure to lens care solutions. The data suggest that keratitis involves biofilm formation or other bacterial adaptations in vivo. PMID:20130275

Mucins in contact lens wear and dry eye conditions.

PubMed

Ramamoorthy, Padmapriya; Nichols, Jason J

2008-08-01

Ocular mucins are thought to play integral roles in ocular surface lubrication, anchoring of the aqueous, stabilizing the lipid components of the tear film, eliminating foreign bodies and pathogens, and with potential involvement in cell cycle mediation and apoptotic activity of ocular surface epithelia. Ocular mucins are of secreted and membrane-associated types. Secreted mucins may be of large gel-forming type or small soluble mucins (e.g., MUC5AC and MUC7). Membrane-associated mucins such as MUCs 1 and 4 are a major component of the glycocalyx. They are thought to render structural support to the microplicae and mediate epithelial cell cycle and apoptotic activity. The alterations in ocular mucins with contact lens wear are unclear. Recent work shows mucin expression may be up-regulated during the early years of contact lens wear, and with long-term lens wear, mucin expression may return to normal levels or sub-normal levels, although this is not well understood. Further, the polar nature of mucins may be associated with their affinity for contact lens surfaces making them a component of contact lens deposition. This has potential implications in the wettability and tolerability of contact lenses, and may be impacted by surface coatings, polymer characteristics, or care solutions. Conjunctival mucin gene expression and secretion may be deficient in several ocular surface disorders associated with dry eye. Deficiency and alterations in glycosylation characteristics of MUC5AC and MUC2 have been reported in both Sjögren and non-Sjögren dry eye types. Decreased binding of the membrane-associated mucin MUC16 to the conjunctival epithelium has been reported in Sjögren dry eye while MUC1 alterations have been reported in Sjögren and non-Sjögren dry eye states. In view of the mucin involvement in dry eye conditions, stimulation of mucus secretion pathways may hold promise in the pharmaceutical treatment of dry eye.

Bacterial flora of the eye and contact lens. Cases during hydrogel lens wear.

PubMed

Callender, M G; Tse, L S; Charles, A M; Lutzi, D

1986-03-01

Bacteriological comparisons between the tear fluids of soft contact lens wearers and noncontact lens wearers indicate that there is an increase in the bacterial population in contact lens wearers but not a significant change in the varieties present. Differences between groups of contact lens wearers appear to depend on the method of disinfection used.

Impact of air-drying lens cases in various locations and positions.

PubMed

Wu, Yvonne T; Zhu, Hua; Willcox, Mark; Stapleton, Fiona

2010-07-01

To determine the rate and type of microbial contamination when contact lens cases are air-dried in two different positions (face up and face down) and in four different locations (toilet, bathroom, office, and bedroom). Unused contact lens cases (n = 97) were rinsed with 2-ml sterile phosphate buffered saline and then placed on facial tissue paper in different locations: humid (toilet and bathroom) and non-humid (office and bedroom) and air-dried at room temperature. After 24 h, the contact lens cases were collected and sampled for microbial numbers and microbial types identified using standard techniques. The microbial profile and the rate of contamination between different locations and positions were compared. Irrespective of the air-drying location, contact lens cases positioned face up had a significantly higher contamination rate (34/48, 71%) compared with contact lens cases air-dried face down (6/49, 12%) (p < 0.001). For those contact lens cases air-dried face up, there was more contamination when placed in humid environments (toilet and bathroom) than in the non-humid environments (office and bedroom) (p = 0.01). However, the contact lens case contamination rate among various locations was similar when contact lens cases were air-dried face down. Total microorganisms recovered from contact lens cases ranged from 0 to 275 colony forming unit per well. The most frequently recovered microorganisms from the contaminated contact lens cases were coagulase-negative Staphylococci, fungi, and Bacillus spp. Thirty-three percent (13/40) of contact lens cases were contaminated with multiple species. Small numbers of microorganisms from the environment may contaminate contact lens cases while cases are air-dried face up. Cases air-dried in humid environments have higher levels of microbial contamination; this is particularly true when contact lens cases are positioned face up. On the basis of this limited study, we would recommend contact lens cases be air-dried face down.

Extended Latanoprost Release from Commercial Contact Lenses: In Vitro Studies Using Corneal Models

PubMed Central

Mohammadi, Saman; Jones, Lyndon; Gorbet, Maud

2014-01-01

In this study, we compared, for the first time, the release of a 432 kDa prostaglandin analogue drug, Latanoprost, from commercially available contact lenses using in vitro models with corneal epithelial cells. Conventional polyHEMA-based and silicone hydrogel soft contact lenses were soaked in drug solution ( solution in phosphate buffered saline). The drug release from the contact lens material and its diffusion through three in vitro models was studied. The three in vitro models consisted of a polyethylene terephthalate (PET) membrane without corneal epithelial cells, a PET membrane with a monolayer of human corneal epithelial cells (HCEC), and a PET membrane with stratified HCEC. In the cell-based in vitro corneal epithelium models, a zero order release was obtained with the silicone hydrogel materials (linear for the duration of the experiment) whereby, after 48 hours, between 4 to 6 of latanoprost (an amount well within the range of the prescribed daily dose for glaucoma patients) was released. In the absence of cells, a significantly lower amount of drug, between 0.3 to 0.5 , was released, (). The difference observed in release from the hydrogel lens materials in the presence and absence of cells emphasizes the importance of using an in vitro corneal model that is more representative of the physiological conditions in the eye to more adequately characterize ophthalmic drug delivery materials. Our results demonstrate how in vitro models with corneal epithelial cells may allow better prediction of in vivo release. It also highlights the potential of drug-soaked silicone hydrogel contact lens materials for drug delivery purposes. PMID:25207851

Co-delivery of timolol and hyaluronic acid from semi-circular ring-implanted contact lenses for the treatment of glaucoma: in vitro and in vivo evaluation.

PubMed

Desai, Ankita R; Maulvi, Furqan A; Pandya, Mihir M; Ranch, Ketan M; Vyas, Bhavin A; Shah, Shailesh A; Shah, Dinesh O

2018-05-29

Glaucoma is a chronic disease, which is currently treated using frequent high dose applications of an eye drop solution; this method is tedious, and most of patients are non-compliant to it. Contact lenses are emerging as a convenient option to sustain the release of ophthalmic drugs. However, the incorporation of a drug/formulation changes the optical and physical properties of contact lenses. Contact lens users have also reported pink eye syndrome; this makes contact lenses unsuitable to be accepted as a medical device. The objective of the present study was to design novel timolol and hyaluronic acid (comfort agent)-loaded semi-circular ring-implanted contact lenses that could uphold the release at therapeutic rates without compromising the critical lens properties. The drug-loaded rings were individually implanted within the periphery of the contact lenses using modified cast-moulding technology. Atomic force microscopy showed an average roughness of 12.38 nm for the implanted lens that was significantly lower as compared to that of the Freshlook contact lenses (116.27 nm). A major amount of timolol was leached (from 46.47 to 58.79%) during the monomer extraction and moist sterilization (autoclave) steps; therefore, the lenses were sterilized by radiation and packaged under dry conditions (dehydrated). The in vitro release data showed sustained release of timolol and hyaluronic acid up to 96 h. The in vivo drug release study on rabbit eyes showed the presence of timolol in tear fluid up to 72 h. The in vivo pharmacodynamics studies showed a reduction in IOP till 144 h with a low drug loading (154 μg) as compared to the case of a single instillation eye drop solution (250 μg). This study has demonstrated the successful application of implantation technology to co-deliver timolol and hyaluronic acid from contact lenses for an extended period of time to treat glaucoma.

Practitioner influence on contact lens prescribing in the UK.

PubMed

Efron, Nathan; Morgan, Philip B

2009-08-01

Contact lenses are mainly fitted by registered optometrists and contact lens opticians in the UK. Data we have gathered from annual contact lens fitting surveys over the past 12 years indicate that, on average, registered optometrists and contact lens opticians undertake 3.2 and 7.1 contact lens fits per week (p<0.0001). More experienced practitioners tend to fit older patients. Practitioners fitting more lenses per year tend to fit a higher proportion of soft lenses. Contact lens opticians tend to fit a higher proportion of patients with planned replacement and daily disposable lenses compared with optometrists.

Citation parameters of contact lens-related articles published in the ophthalmic literature.

PubMed

Cardona, Genís; Sanz, Joan P

2014-09-01

This study aimed at exploring the citation parameters of contact lenses articles published in the Ophthalmology thematic category of the Journal Citation Reports (JCR). The Thompson Reuters Web of Science database was accessed to record bibliometric information and citation parameters of all journals listed under the Ophthalmology area of the 2011 JCR edition, including the journals with main publication interests in the contact lens field. In addition, the same database was used to unveil all contact lens-related articles published in 2011 in the same thematic area, whereupon differences in citation parameters between those articles published in contact lens and non-contact lens-related journals were explored. Significant differences in some bibliometric indicators such as half-life and overall citation count were found between contact lens-related journals (shorter half-life and fewer citations) and the median values for the Ophthalmology thematic area of the JCR. Visual examination of all Ophthalmology journals uncovered a total of 156 contact lens-related articles, published in 28 different journals, with 27 articles each for Contact Lens & Anterior Eye, Eye & Contact Lens, and Optometry and Vision Science. Significant differences in citation parameters were encountered between those articles published in contact lens and non-contact lens source journals. These findings, which disclosed contact lenses to be a fertile area of research, may be of interest to researchers and institutions. Differences in bibliometric indicators are of relevance to avoid unwanted bias when conducting between- and within-discipline comparisons of articles, journals, and researchers.

Microbial contamination of contact lenses, lens care solutions, and their accessories: a literature review.

PubMed

Szczotka-Flynn, Loretta B; Pearlman, Eric; Ghannoum, Mahmoud

2010-03-01

A contact lens (CL) can act as a vector for microorganisms to adhere to and transfer to the ocular surface. Commensal microorganisms that uneventfully cohabitate on lid margins and conjunctivae and potential pathogens that are found transiently on the ocular surface can inoculate CLs in vivo. In the presence of reduced tissue resistance, these resident microorganisms or transient pathogens can invade and colonize the cornea or conjunctiva to produce inflammation or infection. The literature was reviewed and used to summarize the findings over the last 30 years on the identification, enumeration, and classification of microorganisms adherent to CLs and their accessories during the course of normal wear and to hypothesize the role that these microorganisms play in CL infection and inflammation. Lens handling greatly increases the incidence of lens contamination, and the ocular surface has a tremendous ability to destroy organisms. However, even when removed aseptically from the eye, more than half of lenses are found to harbor microorganisms, almost exclusively bacteria. Coagulase-negative Staphylococci are most commonly cultured from worn lenses; however, approximately 10% of lenses harbor Gram-negative and highly pathogenic species, even in asymptomatic subjects. In storage cases, the incidence of positive microbial bioburden is also typically greater than 50%. All types of care solutions can become contaminated, including up to 30% of preserved products. The process of CL-related microbial keratitis and inflammation is thought to be preceded by the presence or transfer or both of microorganisms from the lens to the ocular surface. Thus, this detailed understanding of lens-related bioburden is important in the understanding of factors associated with infectious and inflammatory complications. Promising mechanisms to prevent bacterial colonization on lenses and lens cases are forthcoming, which may decrease the incidence of microbially driven CL complications.

Knowledge, usage and barriers associated with contact lens wear in Ghana.

PubMed

Abokyi, Samuel; Manuh, George; Otchere, Heinz; Ilechie, Alex

2017-10-01

Despite findings that contact lens wear for vision correction provides better quality of life than spectacles, contact lens use in developing countries is low. This study evaluated knowledge, usage and barriers associated with contact lens wear among spectacle wearers in Cape Coast, Ghana. A cross-sectional survey using a structured questionnaire was conducted on an adult population of spectacle wearers to assess their knowledge of contact lens wear for vision correction. The participants were proportionately sampled from three eye clinics in the Cape Coast Metropolis, Ghana. Questionnaires were either self-administered or completed with the help of a research assistant. Of the 422 participants, only 147 (34.8%) knew of contact lens wear for vision correction. The proportion of spectacle wearers reporting history of contact lens wear was 14 (3.3%). Barriers to contact lens wear reported were satisfaction with vision through spectacles 102 (25.0%), lack of adequate information 111 (27.2%), fear of side effects 94 (23.0%) and cost 78 (19.1%). The younger adults and those with higher number of changes of spectacles were more likely to know of contact lenses. Knowledge and usage of contact lenses among spectacle wearers was low. Contact lens education and demonstration of visual performance through fitting of trial contact lenses on potential candidates may help overcome barriers to contact lens wear. Published by Elsevier Ltd.

Antimicrobial Efficacy of Multipurpose Disinfecting Solutions in the Presence of Contact Lenses and Lens Cases.

PubMed

Gabriel, Manal M; McAnally, Cindy; Bartell, John

2018-03-01

The aim of this study was to use antimicrobial efficacy endpoint methodology to determine compatibility of multipurpose disinfecting solutions (MPSs), lens cases, and hydrogel lenses for disinfection (AEEMC) against International Organization for Standardization (ISO)-specified microorganisms and clinical ocular isolates of Stenotrophomonas maltophilia. Six MPSs (PQ/Aldox 1, 2, and 3; PQ/Alexidine; PQ/PHMB; and PHMB) were challenged against ISO-specified microorganisms and S. maltophilia using the AEEMC test. AEEMC tests were performed with and without balafilcon A, etafilcon A, and senofilcon A lenses in lens cases with organic soil. Exposure times included disinfection time (DT) and 24 hr. Additionally, all six MPSs were challenged with two strains of S. maltophilia, based on the ISO Stand-alone test. The efficacy against bacteria for PQ/Aldox and PQ/Alexidine MPSs was not diminished by the presence of lenses. The efficacy of PQ/PHMB and PHMB MPSs against Serratia marcescens was significantly reduced compared with the no-lens control at DT for at least one lens type. The PHMB MPS with lenses present also demonstrated reduced efficacy against Staphylococcus aureus at DT versus the control. PQ/Aldox MPSs retained activity against Fusarium solani with lenses present; however, all other test MPSs demonstrated reduced F. solani efficacy at DT with lenses present. With lenses, all MPSs showed reduced efficacy against Candida albicans. AEEMC antimicrobial efficacy test results vary based on challenge microorganism, contact lenses, and MPS biocide systems. This study highlights the importance of evaluating MPSs for compatibility with lenses and lens cases.

Antimicrobial Efficacy of Multipurpose Disinfecting Solutions in the Presence of Contact Lenses and Lens Cases

PubMed Central

McAnally, Cindy; Bartell, John

2018-01-01

Objective: The aim of this study was to use antimicrobial efficacy endpoint methodology to determine compatibility of multipurpose disinfecting solutions (MPSs), lens cases, and hydrogel lenses for disinfection (AEEMC) against International Organization for Standardization (ISO)–specified microorganisms and clinical ocular isolates of Stenotrophomonas maltophilia. Methods: Six MPSs (PQ/Aldox 1, 2, and 3; PQ/Alexidine; PQ/PHMB; and PHMB) were challenged against ISO-specified microorganisms and S. maltophilia using the AEEMC test. AEEMC tests were performed with and without balafilcon A, etafilcon A, and senofilcon A lenses in lens cases with organic soil. Exposure times included disinfection time (DT) and 24 hr. Additionally, all six MPSs were challenged with two strains of S. maltophilia, based on the ISO Stand-alone test. Results: The efficacy against bacteria for PQ/Aldox and PQ/Alexidine MPSs was not diminished by the presence of lenses. The efficacy of PQ/PHMB and PHMB MPSs against Serratia marcescens was significantly reduced compared with the no-lens control at DT for at least one lens type. The PHMB MPS with lenses present also demonstrated reduced efficacy against Staphylococcus aureus at DT versus the control. PQ/Aldox MPSs retained activity against Fusarium solani with lenses present; however, all other test MPSs demonstrated reduced F. solani efficacy at DT with lenses present. With lenses, all MPSs showed reduced efficacy against Candida albicans. Conclusions: AEEMC antimicrobial efficacy test results vary based on challenge microorganism, contact lenses, and MPS biocide systems. This study highlights the importance of evaluating MPSs for compatibility with lenses and lens cases. PMID:27598555

Comparative efficacy of contact lens disinfection solutions.

PubMed

Lowe, R; Vallas, V; Brennan, N A

1992-01-01

Using the D value method of analysis, we evaluated the relative antimicrobial effectiveness of eight contact lens disinfection solutions against a standard population of challenge organisms as defined in the Microbiological Guidelines proposed by the Food and Drug Administration (FDA). Six bacteria (Escherichia coli, Staphylococcus aureus, S. epidermidis, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Serratia marcescens) and two fungi (Aspergillus fumigatus, Candida albicans) were investigated. The disinfectants included hydrogen peroxide (AOSept, MiraSept, Oxysept), chlorine-based solutions (Aerotab and Softab), soaking solutions containing synthetic, high molecular weight preservatives (ReNu and Opti-Free) and a thimerosal preserved soaking solution (Hydrocare Cleaning and Soaking Solution). The one-step hydrogen peroxide system (AOSept) was evaluated both with and without the catalytic disk. To facilitate comparison of the disinfecting solutions, we defined a new measure of performance, namely "power" of solution. This has an advantage over the "safety factor" because the solution power is independent of the size of the initial inoculum. Because different approaches to analysis may yield a wide range of D values for one set of survival data we call for adoption of a standardized approach. Our results suggest that one of the chlorine-based solutions fails to meet the FDA recommendations for bacterial challenge. Most solutions performed poorly against mycotic challenge. However, when used over longer disinfecting periods, 3% hydrogen peroxide and the Hydrocare solution gave adequate performance against fungi.

Aberrations associated with rigid contact lenses.

PubMed

Atchison, D A

1995-10-01

A rigid contact lens on an eye can produce levels of spherical aberration very different from those produced by a spectacle lens in front of the eye. These levels are considerably affected by contact lens surface asphericity. Change in longitudinal spherical aberration associated with aspherizing a contact lens surface is well predicted by a simple equation for change in sagittal power of the surface. Displacing an aspheric contact lens on the eye can produce considerable defocus, which is well predicted by simple equations for change in sagittal and tangential surface powers. The best refractive correction with contact lenses can be determined only by overrefraction with a patient wearing a contact lens of power and characteristics similar to that which will be prescribed. An aspheric contact lens that moves to a considerable extent on the eye will cause more unstable vision than will a spherical lens that moves to the same extent.

Dendritiform Keratopathy Associated with Exposure to Polyquarternium-1, a Common Ophthalmic Preservative.

PubMed

Matoba, Alice Y; Peterson, Jeff R; Wilhelmus, Kirk R

2016-03-01

To describe dendritiform keratopathy associated with exposure to polyquaternium-1, a common preservative found in contact lens solutions and tear replacement products. Case series. Sixteen patients who demonstrated dendritiform keratopathy during topical ophthalmic exposure to polyquaternium-1. Records were reviewed of all patients diagnosed with dendritiform keratopathy between 1999 and 2014 who had documented exposure to contact lens care disinfecting solutions or artificial tear solutions containing polyquaternium-1. Patients were excluded who had coexisting potential causes for dendritiform keratopathy, such as prior herpes simplex keratitis, varicella-zoster viral keratitis, the linear form of Thygeson's superficial keratitis, epithelial regeneration line, Acanthamoeba keratitis, mucus plaque keratopathy, medication-related keratopathy, or limbal stem cell deficiency characterized by conjunctivalization of the corneal epithelium. Effect of discontinuation of exposure to polyquaternium-1 on the dendritiform keratopathy. Sixteen patients demonstrated dendritiform keratopathy after exposure to the preservative polyquaternium-1. Thirteen patients had a history of recent exposure to contact lens disinfecting solutions (Opti-Free, Equate) containing polyquaternium-1. Three patients used a tear replacement product (Systane) containing a polyquaternium-1 preservative. Four patients were treated with antiviral medications for presumed herpes simplex keratitis; 4 patients underwent diagnostic testing for Acanthamoeba keratitis. Two additional patients were diagnosed sequentially with herpes simplex keratitis, then Acanthamoeba keratitis before referral. All dendritiform lesions resolved within 2 to 6 weeks after elimination of exposure to polyquaternium-1. Ophthalmic products containing polyquaternium-1 may cause dendritiform keratopathy that may be confused with infections of the superficial cornea, such as herpes simplex virus keratitis or Acanthamoeba keratitis. Copyright © 2016 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Tear analysis in contact lens wearers.

PubMed Central

Farris, R L

1985-01-01

Tear analysis in contact lens wearers was compared with tear analysis in aphakics without contact lens wear and normal phakic patients. Subjects were divided into five groups: group 1, aphakic without contact lens; group 2, phakic with daily-wear hard contact lens; group 3, phakic with daily-wear soft contact lens; group 4, phakic with extended-wear soft contact lens; and group 5, aphakic with extended-wear soft contact lens. The experimental groups were compared with age- and sex-matched control groups for statistical analysis of tear variables by means of the Student's t-test. The variables measured were tear osmolarity, tear albumin, and lysozyme and lactoferrin concentrations in basal and reflex tears. Highly significant elevations of tear osmolarity were found in aphakic subjects without contact lenses. Less significant differences in tear osmolarity were found in phakic subjects with hard daily-wear lenses or with extended-wear soft lenses. Tear albumin, lysozyme, and lactoferrin in basal and reflex tears were not significantly different in the different groups of contact lens wearers or in the group of aphakic subjects without contact lenses compared with their control groups. Individual variations in tear albumin, lysozyme, and lactoferrin appeared to be responsible for the inability to demonstrate significant differences in tear composition in association with the wearing of different types of contact lenses. Older and aphakic patients demonstrated a tendency to have increased concentrations of proteins in the tears compared with younger, phakic contact lens wearers and normal controls without contact lenses. PMID:3914131

Inactivation of Acanthamoeba spp. and Other Ocular Pathogens by Application of Cold Atmospheric Gas Plasma

PubMed Central

Shama, Gilbert; Andrew, Peter W.

2016-01-01

Currently there are estimated to be approximately 3.7 million contact lens wearers in the United Kingdom and 39.2 million in North America. Contact lens wear is a major risk factor for developing an infection of the cornea known as keratitis due to poor lens hygiene practices. While there is an international standard for testing disinfection methods against bacteria and fungi (ISO 14729), no such guidelines exist for the protozoan Acanthamoeba, which causes a potentially blinding keratitis most commonly seen in contact lens wearers, and as a result, many commercially available disinfecting solutions show incomplete disinfection after 6 and 24 h of exposure. Challenge test assays based on international standard ISO 14729 were used to determine the antimicrobial activity of cold atmospheric gas plasma (CAP) against Pseudomonas aeruginosa, Candida albicans, and trophozoites and cysts of Acanthamoeba polyphaga and Acanthamoeba castellanii. P. aeruginosa and C. albicans were completely inactivated in 0.5 min and 2 min, respectively, and trophozoites of A. polyphaga and A. castellanii were completely inactivated in 1 min and 2 min, respectively. Furthermore, for the highly resistant cyst stage of both species, complete inactivation was achieved after 4 min of exposure to CAP. This study demonstrates that the CAP technology is highly effective against bacterial, fungal, and protozoan pathogens. The further development of this technology has enormous potential, as this approach is able to deliver the complete inactivation of ocular pathogens in minutes, in contrast to commercial multipurpose disinfecting solutions that require a minimum of 6 h. PMID:26994079

The effect of the timing of the cessation of contact lens use on the results of biometry.

PubMed

Goudie, Colin; Tatham, Andrew; Davies, Rhys; Sifton, Alison; Wright, Mark

2018-06-01

Current guidelines vary regarding when to remove contact lenses prior to performing biometry, and there is no clear evidence behind these guidelines. This study aimed to determine the effect of soft contact lens wear on biometric measurements by examining the change in predicted lens power for emmetropia at several time points following removal of soft contact lenses. A prospective, controlled study of healthy soft contact lens wearers. Biometry was performed immediately after removing contact lenses and then after 2, 4 and 7 days of no contact lens use. Healthy non-contact lens wearers were used as controls. All measurements were taken with the Zeiss IOLMaster. In all, 14 subjects and 13 controls were recruited. There was no significant difference in age or gender between groups. Eight of the fourteen subjects wore daily disposable CLs, two wore 2-weekly and four wore monthly soft CLs. Measurements from controls and contact lens-wearing subjects showed similar degrees of variation over time. The within-subject SD in predicted intraocular lens (IOL) power for emmetropia for contact lens wearers was 0.20 D (95% CI 0.16-0.25 D) compared to 0.18 D (95% CI 0.12-0.26 D) for controls. There is a significant variation in UK practice regarding advice on the timing of cessation of contact lens wear prior to having biometry performed. Our study suggests that it is likely that soft contact lens wearers are currently being advised to remove their contact lenses for an unnecessarily long period of time prior to having biometry performed.

Putting vital stains in context.

PubMed

Efron, Nathan

2013-07-01

While vital staining remains a cornerstone in the diagnosis of ocular disease and contact lens complications, there are many misconceptions regarding the properties of commonly used dyes by eye-care practitioners and what is and what is not corneal staining after instillation of sodium fluorescein. Similarly, the proper use and diagnostic utility of rose Bengal and lissamine green B, the other two ophthalmic dyes commonly used for assessing ocular complications, have similarly remained unclear. Due to the limitations of vital stains for definitive diagnosis, concomitant signs and symptoms in addition to a complete patient history are required. Over the past decade, there have been many reports of a type of corneal staining--often referred to as solution-induced corneal staining (SICS)--that is observed with the use of multipurpose solutions in combination with soft lenses, more specifically silicone hydrogel lenses. Some authors believe that SICS is a sign of lens/solution incompatibility; however, new research shows that SICS may be neither a measure of lens/solution biocompatibility nor 'true' corneal staining, as that observed in pathological situations. A large component of SICS may be a benign phenomenon, known as preservative-associated transient hyperfluorescence (PATH). There is a lack of correlated signs and/or symptoms with SICS/PATH. Several properties of SICS/PATH, such as appearance and duration, differentiate it from pathological corneal staining. This paper reviews the properties of vital stains, their use and limitations in assessment of the ocular surface, the aetiology of corneal staining, characteristics of SICS/PATH that differentiate it from pathological corneal staining and what the SICS/PATH phenomenon means for contact lens-wearing patients. © 2012 The Author. Clinical and Experimental Optometry © 2012 Optometrists Association Australia.

Method of holding optical elements without deformation during their fabrication

DOEpatents

Hed, P.P.

1997-04-29

An improved method for securing and removing an optical element to and from a blocking tool without causing deformation of the optical element is disclosed. A lens tissue is placed on the top surface of the blocking tool. Dots of UV cement are applied to the lens tissue without any of the dots contacting each other. An optical element is placed on top of the blocking tool with the lens tissue sandwiched therebetween. The UV cement is then cured. After subsequent fabrication steps, the bonded blocking tool, lens tissue, and optical element are placed in a debonding solution to soften the UV cement. The optical element is then removed from the blocking tool. 16 figs.

Method of holding optical elements without deformation during their fabrication

DOEpatents

Hed, P. Paul

1997-01-01

An improved method for securing and removing an optical element to and from a blocking tool without causing deformation of the optical element. A lens tissue is placed on the top surface of the blocking tool. Dots of UV cement are applied to the lens tissue without any of the dots contacting each other. An optical element is placed on top of the blocking tool with the lens tissue sandwiched therebetween. The UV cement is then cured. After subsequent fabrication steps, the bonded blocking tool, lens tissue, and optical element are placed in a debonding solution to soften the UV cement. The optical element is then removed from the blocking tool.

The use of dimethyl sulfoxide in contact lens disinfectants is a potential preventative strategy against contracting Acanthamoeba keratitis.

PubMed

Siddiqui, Ruqaiyyah; Aqeel, Yousuf; Khan, Naveed Ahmed

2016-10-01

Acanthamoeba castellanii is the causative agent of blinding keratitis. Though reported in non-contact lens wearers, it is most frequently associated with improper use of contact lens. For contact lens wearers, amoebae attachment to the lens is a critical first step, followed by amoebae binding to the corneal epithelial cells during extended lens wear. Acanthamoeba attachment to surfaces (biological or inert) and migration is an active process and occurs during the trophozoite stage. Thus retaining amoebae in the cyst stage (dormant form) offers an added preventative measure in impeding parasite traversal from the contact lens onto the cornea. Here, we showed that as low as 3% DMSO, abolished A. castellanii excystation. Based on the findings, it is proposed that DMSO should be included in the contact lens disinfectants as an added preventative strategy against contracting Acanthamoeba keratitis. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

21 CFR 800.12 - Contact lens solutions and tablets; tamper-resistant packaging.

Code of Federal Regulations, 2010 CFR

2010-04-01

...-resistant retail packages, there is the opportunity for the malicious adulteration of these products with... confidence in the security of the packages of over-the-counter (OTC) health care products. The Food and Drug... used to make such a solution for retail sale that is not packaged in a tamper-resistant package and...

21 CFR 800.12 - Contact lens solutions and tablets; tamper-resistant packaging.

Code of Federal Regulations, 2011 CFR

2011-04-01

...-resistant retail packages, there is the opportunity for the malicious adulteration of these products with... confidence in the security of the packages of over-the-counter (OTC) health care products. The Food and Drug... used to make such a solution for retail sale that is not packaged in a tamper-resistant package and...

21 CFR 800.12 - Contact lens solutions and tablets; tamper-resistant packaging.

Code of Federal Regulations, 2012 CFR

2012-04-01

...-resistant retail packages, there is the opportunity for the malicious adulteration of these products with... confidence in the security of the packages of over-the-counter (OTC) health care products. The Food and Drug... used to make such a solution for retail sale that is not packaged in a tamper-resistant package and...

21 CFR 800.12 - Contact lens solutions and tablets; tamper-resistant packaging.

Code of Federal Regulations, 2013 CFR

2013-04-01

...-resistant retail packages, there is the opportunity for the malicious adulteration of these products with... confidence in the security of the packages of over-the-counter (OTC) health care products. The Food and Drug... used to make such a solution for retail sale that is not packaged in a tamper-resistant package and...

21 CFR 800.12 - Contact lens solutions and tablets; tamper-resistant packaging.

Code of Federal Regulations, 2014 CFR

2014-04-01

...-resistant retail packages, there is the opportunity for the malicious adulteration of these products with... confidence in the security of the packages of over-the-counter (OTC) health care products. The Food and Drug... used to make such a solution for retail sale that is not packaged in a tamper-resistant package and...

Forensic Analysis of a Contact Lens in a Murder Case.

PubMed

Zwerling, Charles S

2016-03-01

Contact lenses have had rare relevance in trials and/or investigations. After 5 years of burial, orbital remnants were retrieved from an exhumed body and subsequently identified as a key piece of material evidence in a murder trial. The exhumed case materials were evaluated under laboratory conditions and were determined to be contact lens remnants. Contact lens fracture and burial simulation studies were performed to provide additional corroboration of the physical findings of the exhumed contact lens remnants. This material evidence was instrumental in providing factual proof refuting the defendant's testimony in the murder trial. A brief history of contact lens composition and use is provided for understanding the methods and observational results. This forensic case study represents the first published documentation of a contact lens from an exhumed body being used in a murder investigation and establishes an operational procedure for future forensic contact lens examinations. © 2016 American Academy of Forensic Sciences.

Non-toric extended depth of focus contact lenses for astigmatism and presbyopia correction

NASA Astrophysics Data System (ADS)

Ben Yaish, Shai; Zlotnik, Alex; Yehezkel, Oren; Lahav-Yacouel, Karen; Belkin, Michael; Zalevsky, Zeev

2010-02-01

Purpose: Testing whether the extended depth of focus technology embedded on non-toric contact lenses is a suitable treatment for both astigmatism and presbyopia. Methods: The extended depth of focus pattern consisting of microndepth concentric grooves was engraved on a surface of a mono-focal soft contact lens. These grooves create an interference pattern extending the focus from a point to a length of about 1mm providing a 3.00D extension in the depth of focus. The extension in the depth of focus provides high quality focused imaging capabilities from near through intermediate and up to far ranges. Due to the angular symmetry of the engraved pattern the extension in the depth of focus can also resolve regular as well as irregular astigmatism aberrations. Results: The contact lens was tested on a group of 8 astigmatic and 13 subjects with presbyopia. Average correction of 0.70D for astigmatism and 1.50D for presbyopia was demonstrated. Conclusions: The extended depth of focus technology in a non-toric contact lens corrects simultaneously astigmatism and presbyopia. The proposed solution is based upon interference rather than diffraction effects and thus it is characterized by high energetic efficiency to the retina plane as well as reduced chromatic aberrations.

UVB-induced epidermal pigmentation in mice eyes with no contact lens wear and non-UVB blocking and UVB blocking contact lens wear.

PubMed

Hiramoto, Keiichi; Kobayashi, Hiromi; Yamate, Yurika; Ishii, Masamitsu; Sato, Takao; Inoue, Masayasu

2013-02-01

Irradiation by ultraviolet (UV) B is known to increase the number of Dopa-positive melanocytes in the skin. This study examines the effectiveness of a contact lens for the defense of UVB eye irradiation-induced pigmentation. A 2.5 kJ/m(2) dose of UVB radiation was delivered by a sunlamp to the eye of C57BL/6j male mice, and changes in the expression of Dopa-positive melanocytes in the epidermis and the plasma level of alpha-melanocyte-stimulating hormone (α-MSH) was analyzed. The degree of change in the Dopa-positive melanocytes expression was reduced by UVB blocking contact lens using mice given UVB irradiation to the eye. The plasma level of α-MSH increased in the C57BL/6j mice after irradiation to the eye, but there was no increase in the UVB blocking contact lens mice given UVB irradiation to the eye. Both the increase of the expression of Dopa-positive melanocytes and the plasma level of α-MSH were strongly suppressed by an alignment fitting UVB blocking contact lens and only a slightly suspended UVB blocking contact lens. In addition, these changes were successfully inhibited by a UVB blocking contact lens but not by a non-UVB blocking contact lens with a similar absorbance. These observations suggest that the UVB blocking contact lens inhibits the pigmentation of the epidermis in mice by suppressing of the α-MSH. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

A Class I (Senofilcon A) Soft Contact Lens Prevents UVB-Induced Ocular Effects, Including Cataract, in the Rabbit In Vivo

PubMed Central

Lin, Li-Ren; Leverenz, Victor R.; Dang, Loan

2011-01-01

Purpose. UVB radiation from sunlight is known to be a risk factor for human cataract. The purpose in this study was to investigate the ability of a class I UV-blocking soft contact lens to protect against UVB-induced effects on the ocular tissues of the rabbit in vivo. Methods. Eyes of rabbits were exposed to UVB light for 30 minutes (270–360 nm, peak at 310 nm, 1.7 mW/cm2 on the cornea). Eyes were irradiated in the presence of either a UV-blocking senofilcon A contact lens, a minimally UV-blocking lotrafilcon A contact lens, or no contact lens at all. Effects on the cornea and lens were evaluated at various times after exposure. Results. Eyes irradiated with no contact lens protection showed corneal epithelial cell loss plus lens epithelial cell swelling, vacuole formation, and DNA single-strand breaks, as well as lens anterior subcapsular opacification. The senofilcon A lens protected nearly completely against the UVB-induced effects, whereas the lotrafilcon A lens showed no protection. Conclusions. The results indicate that use of a senofilcon A contact lens is beneficial in protecting ocular tissues of the rabbit against the harmful effects of UVB light, including photokeratitis and cataract. PMID:21421866

A class I (Senofilcon A) soft contact lens prevents UVB-induced ocular effects, including cataract, in the rabbit in vivo.

PubMed

Giblin, Frank J; Lin, Li-Ren; Leverenz, Victor R; Dang, Loan

2011-06-01

UVB radiation from sunlight is known to be a risk factor for human cataract. The purpose in this study was to investigate the ability of a class I UV-blocking soft contact lens to protect against UVB-induced effects on the ocular tissues of the rabbit in vivo. Eyes of rabbits were exposed to UVB light for 30 minutes (270-360 nm, peak at 310 nm, 1.7 mW/cm(2) on the cornea). Eyes were irradiated in the presence of either a UV-blocking senofilcon A contact lens, a minimally UV-blocking lotrafilcon A contact lens, or no contact lens at all. Effects on the cornea and lens were evaluated at various times after exposure. Eyes irradiated with no contact lens protection showed corneal epithelial cell loss plus lens epithelial cell swelling, vacuole formation, and DNA single-strand breaks, as well as lens anterior subcapsular opacification. The senofilcon A lens protected nearly completely against the UVB-induced effects, whereas the lotrafilcon A lens showed no protection. The results indicate that use of a senofilcon A contact lens is beneficial in protecting ocular tissues of the rabbit against the harmful effects of UVB light, including photokeratitis and cataract.

21 CFR 886.5925 - Soft (hydrophilic) contact lens.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Soft (hydrophilic) contact lens. 886.5925 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5925 Soft (hydrophilic) contact lens. (a) Identification. A soft (hydrophilic) contact lens is a device intended to be worn directly...

21 CFR 886.5420 - Contact lens inserter/remover.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Contact lens inserter/remover. 886.5420 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5420 Contact lens inserter/remover. (a) Identification. A contact lens inserter/remover is a handheld device intended to insert or remove...

21 CFR 886.5925 - Soft (hydrophilic) contact lens.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Soft (hydrophilic) contact lens. 886.5925 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5925 Soft (hydrophilic) contact lens. (a) Identification. A soft (hydrophilic) contact lens is a device intended to be worn directly...

21 CFR 886.1430 - Ophthalmic contact lens radius measuring device.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ophthalmic contact lens radius measuring device... lens radius measuring device. (a) Identification. An ophthalmic contact lens radius measuring device is... lens. (b) Classification. Class I (general controls). The device is exempt from the premarket...

Contact Lens Care

MedlinePlus

... your prescription expires Lens measurements The contact lens brand name and material Your doctor’s name and contact ... mail-order sellers may send you a different brand. Contact lenses may look the same, but materials ...

Tear exchange and contact lenses: A review

PubMed Central

Muntz, Alex; Subbaraman, Lakshman N.; Sorbara, Luigina; Jones, Lyndon

2015-01-01

Tear exchange beneath a contact lens facilitates ongoing fluid replenishment between the ocular surface and the lens. This exchange is considerably lower during the wear of soft lenses compared with rigid lenses. As a result, the accumulation of tear film debris and metabolic by-products between the cornea and a soft contact lens increases, potentially leading to complications. Lens design innovations have been proposed, but no substantial improvement in soft lens tear exchange has been reported. Researchers have determined post-lens tear exchange using several methods, notably fluorophotometry. However, due to technological limitations, little remains known about tear hydrodynamics around the lens and, to-date, true tear exchange with contact lenses has not been shown. Further knowledge regarding tear exchange could be vital in aiding better contact lens design, with the prospect of alleviating certain adverse ocular responses. This article reviews the literature to-date on the significance, implications and measurement of tear exchange with contact lenses. PMID:25575892

Evaluation of safety and efficacy of a new multipurpose disinfecting solution on silicone hydrogel contact lenses.

PubMed

Pinto-Fraga, José; Blázquez Arauzo, Francisco; Urbano Rodríguez, Rubén; González-García, María J

2015-01-01

To evaluate the safety and efficacy of a new multipurpose disinfecting solution (MPDS) with a formulation that includes aloe vera on its composition. This is a prospective, randomized, double-masked clinical trial with a crossover design that included seven examinations. Two different MPDSs, Avizor Alvera® (study solution) and All Clean Soft® (control solution), each were used for 1 month. Comfilcon A silicone hydrogel contact lenses were used during the trial. The main outcome variables were corneal staining and deposits on the surfaces of the contact lenses. Other parameters including ocular surface response, contact lens wettability, user satisfaction, and adverse events, were analyzed according to the International Organization for Standardization (ISO) 11980:2010 guidance for clinical investigation. Twenty subjects (10 women, 10 men) (mean age, 27.7±5.6 years; range, 20-41) were included. No differences between both MPDSs were found in the percentage of subjects with corneal staining >0 at day 30 (study: 35%, control: 50%; p=0.46); neither in the percentage of subjects with deposits on the surface of the contact lens >0 at day 30 (study: 26.32%, control: 52.63%; p=0.18). The study MPDS received higher rates in comfort (study: 8.14±1.09, control: 7.94±0.92; p=0.56) and satisfaction at day 30 (study: 8.63±0.91, control: 8.29±0.80; p=0.19), however the scores were not significantly different with the control MPDS. The clinical trial showed that the study MPDS is safe, efficient, and has acceptable physiologic tolerance, according to the ISO 11980:2010 guidance for clinical investigation. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

21 CFR 886.5916 - Rigid gas permeable contact lens.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rigid gas permeable contact lens. 886.5916 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5916 Rigid gas permeable contact lens. (a) Identification. A rigid gas permeable contact lens is a device intended to be worn directly...

21 CFR 886.5916 - Rigid gas permeable contact lens.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Rigid gas permeable contact lens. 886.5916 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5916 Rigid gas permeable contact lens. (a) Identification. A rigid gas permeable contact lens is a device intended to be worn directly...

Contact Lens-related Complications: A Review

PubMed Central

Alipour, Fateme; Khaheshi, Saeed; Soleimanzadeh, Mahya; Heidarzadeh, Somayeh; Heydarzadeh, Sepideh

2017-01-01

Contact lens-related problems are common and can result in severe sight-threatening complications or contact lens drop out if not addressed properly. We systematically reviewed the most important and the most common contact lens-related complications and their diagnosis, epidemiology, and management according to the literature published in the last 20 years. PMID:28540012

National Apprenticeship and Training Standards for Optical Technician (Contact Lens Technician).

ERIC Educational Resources Information Center

Manpower Administration (DOL), Washington, DC. Bureau of Apprenticeship and Training.

A statement of policy of the Contact Lens Society of America regarding contact lens filters is followed by national apprenticeship and training standards for optical technicians approved and adopted by the Contact Lens Society of America in accordance with the basic standards recommended by the Bureau of Apprenticeship and Training of the…

Impact of Cosmetics on the Physical Dimension and Optical Performance of Silicone Hydrogel Contact Lenses.

PubMed

Luensmann, Doerte; Yu, Mili; Yang, Jeffery; Srinivasan, Sruthi; Jones, Lyndon

2015-07-01

To evaluate the impact of cosmetics on silicone hydrogel (SiHy) contact lens shape, lens power, and optical performance. In this in vitro experiment, 7 SiHy materials were coated with 9 marketed brands of cosmetics, including hand creams (HCs) (3), eye makeup removers (MRs) (3), and mascaras (3). Diameter, sagittal depth, and base curve were determined using the Chiltern (Optimec Limited), whereas lens power and optical performance were assessed using the Contest Plus (Rotlex). Six replicates were used for each lens and cosmetic combination. Measurements were repeated after a cleaning cycle using a one-step hydrogen peroxide solution. Makeup removers had the greatest impact on diameter, sagittal depth, and base curve, resulting in changes of up to 0.5, 0.15, and 0.77 mm, respectively. The HCs and mascaras had little impact on these parameters; however, differences were observed between lens types. Optical performance was reduced with all mascaras, and a decrease of greater than 2 units on a 0 to 10 scale (10=uniform power distribution) was seen for 5 lens types exposed to waterproof mascara (P<0.01). Most HCs and MRs had minimal impact on image quality. Lens power did not change with any of the cosmetics (± 0.25 diopter; P>0.05). Lens cleaning resulted in some recovery of the lens parameters, and efficiency varied between cosmetics. Some eye MRs and waterproof mascaras changed the shape and optical performance of some SiHy lenses. Further research is needed to understand the clinical implications for SiHy lens wearers using cosmetics.

The effect of successful contact lens wear on mucosal immunity of the eye.

PubMed

McClellan, K A; Cripps, A W; Clancy, R L; Billson, F A

1998-08-01

This study aimed to assess the effect of contact lens wear on the mucosal defenses of the outer eye against infection. A case-controlled study of daily contact lens wearers in their initial 6 months of contact lens wear. Contact lens wearers (mean age, 23.1 years; 47 subjects) were compared with age-matched control subjects (mean age, 24.7 years; 44 subjects). Outer eye defenses were studied by assay of tear constituents and quantitative conjunctival microbiology. Antimicrobial activity of tears was studied by assay of total immunoglobulin A (IgA), IgA isotype-specific antibodies reactive with Escherichia coli, Haemophilus influenzae, Staphylococcus epidermidis, albumin and lysozyme, and the ocular surface microbial load determined using quantitative microbiology of the conjunctival sac. The IgA isotype-specific antibodies reactive with E. coli (P = 0.03) and S. epidermidis (P = 0.068) were lower in contact lens wearers, but antibody:albumin ratios were not significantly different in the two groups. Contact lens wear also had no significant effect on tear IgA, albumin, or lysozyme or its ratios with albumin. Bacterial numbers and colonization rates for coagulase-negative staphylococci were greater in contact lens wearers than in age-matched control subjects. Corynebacterium sp. and non-Enterobacteriaceae (P = 0.007) were isolated more frequently and in greater numbers from contact lens wearers. Colonization rates were increased for Corynebacterium sp., but non-Enterobacteriaceae were transient. In both daily contact lens wearers and age-matched control subjects, most conjunctival flora were transient rather than colonizing, and no subject developed an outer eye infection during the study. These results suggest that daily contact lens wear does not significantly alter the mucosal defenses of the outer eye that function to eliminate organisms from the conjunctival sac and prevent outer eye infection.

Fluorescent solute-partitioning characterization of layered soft contact lenses.

PubMed

Dursch, T J; Liu, D E; Oh, Y; Radke, C J

2015-03-01

Partitioning of aqueous packaging, wetting, and care-solution agents into and out of soft contact lenses (SCLs) is important for improving wear comfort and also for characterizing lens physico-chemical properties. We illustrate both features of partitioning by application of fluorescent-solute partitioning into DAILIES TOTAL1® (delefilcon A) water-gradient SCLs, which exhibit a layered structure of a silicone-hydrogel (SiHy) core sandwiched between thin surface-gel layers. Two-photon fluorescence confocal laser-scanning microscopy and attenuated total-reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) characterize the lens and assess uptake profiles of six prototypical fluorescent solutes. Comparison of solute uptake in a SiHy-core prototype lens (i.e., O2OPTIX(TM)) validates the core SiHy structure of DAILIESTOTAL1®. To establish surface-layer charge, partition coefficients and water contents are obtained for aqueous pH values of 4 and 7.4. Solute fluorescence-intensity profiles clearly confirm a layered structure for the DAILIES TOTAL1® lenses. In all cases, aqueous solute partition coefficients are greater in the surface layers than in the SiHy core, signifying higher water in the surface gels. ATR-FTIR confirms surface-layer mass water contents of 82±3%. Water uptake and hydrophilic-solute uptake at pH 4 compared with that at pH 7.4 reveal that the surface-gel layers are anionic at physiologic pH 7.4, whereas both the SiHy core and O2OPTIX™ (lotrafilcon B) are nonionic. We successfully confirm the layered structure of DAILIES TOTAL1®, consisting of an 80-μm-thick SiHy core surrounded by 10-μm-thick polyelectrolyte surface-gel layers of significantly greater water content and aqueous solute uptake compared with the core. Accordingly, fluorescent-solute partitioning in SCLs provides information on gel structure and composition, in addition to quantifying uptake and release amounts and rates. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Experimental studies on soft contact lenses for controlled ocular delivery of pirfinedone: in vitro and in vivo.

PubMed

Yang, Mei; Yang, Yangfan; Lei, Ming; Ye, Chengtian; Zhao, Chunshun; Xu, Jiangang; Wu, Kaili; Yu, Minbin

2016-11-01

Pirfinedone (PFD) is a novel agent which has the potential to prevent scarring in the eyes. The 0.5% PFD eye drops exhibits poor bioavailability. Whereas, the feasibility of using contact lens as ocular drug delivery device initiated novel possibilities. To evaluate the delivery of PFD by soft contact lens (SCL) in vivo, we screened the most suitable lens material for PFD among various commercially available SCL materials in vitro. Firstly, 11 different SCLs (-1.00 diopter) were respectively soaked in 2 ml of 0.05% PFD-loading solution for 24 h to fully absorb drug, and then placed in fresh phosphate buffered saline (PBS) to release the drug. PFD concentration in PBS was determined by ultraviolet absorbance at 310 nm. Secondly, by immersing in 2 ml of 0.5% PFD eye drops for 24 h, the polymacon lens (0.00 diopter) was then placed on the cornea of New Zealand rabbits. PFD concentrations were detected by high performance liquid chromatography (HPLC) in tears, aqueous humor, conjunctiva, cornea, and sclera at different time points. PFD showed some affinity for pHEMA-based lenses and the polymacon lens more slowly released more amount of PFD than any other lens in vitro (p < 0.001). Compared with eye drops, drug-loaded SCLs greatly enhanced the retention time and concentrations of PFD in cornea and aqueous humor and consequently improved the bioavailability of PFD. Polymacon-based SCL is probably a promising vehicle to be an effective ophthalmic delivery system for PFD.

An Experimental Model to Study the Impact of Lipid Oxidation on Contact Lens Deposition In Vitro.

PubMed

Schuett, Burkhardt S; Millar, Thomas J

2017-09-01

This study was to establish a controlled in vitro test system to study the effect of lipid oxidation on lipid deposition on contact lenses. Fatty acids with varying degree of unsaturation were oxidized using the Fenton reaction. The degree of lipid oxidation and the lipid moieties formed during the oxidation were identified and estimated by various lipid staining techniques following separation with thin-layer chromatography, and by measuring thiobarbituric acid reactive substances or peroxides in solution. Two different silicone hydrogel-based contact lenses (Balafilcon A and Senofilcon A) were incubated with fatty acids laced with radioactive tracer oxidized to varying degrees, and the amount of lipid deposition was measured using unoxidized lipid samples as controls. The Fenton reaction together with the analytical methods to analyze the lipid oxidation can be used to control oxidation of lipids to a desired amount. In general, saturated fatty acids are not oxidized, the monounsaturated oleic acid produced peroxides while poly-unsaturated lipids initially produced peroxides and then fragmented into reactive aldehydes. Incubation with mildly oxidized lipids (most likely lipid peroxides) resulted in increased lipid deposition on Balafilcon A lenses compared to unoxidized lipids, but this was not observed for Senofilcon A lenses. Further oxidation of the lipids (carbon chain breakup) on the other hand resulted in diminished lipid deposition for both contact lens types. This study provides a method for inducing and controlling lipid oxidation so that the effect of lipid oxidation on contact lens binding can be compared. It could be shown that the degree of lipid oxidation has different effects on the lipid deposition on different contact lens types.

Nonclinical safety evaluation of boric acid and a novel borate-buffered contact lens multi-purpose solution, Biotrue™ multi-purpose solution.

PubMed

Lehmann, David M; Cavet, Megan E; Richardson, Mary E

2010-12-01

Multipurpose solutions (MPS) often contain low concentrations of boric acid as a buffering agent. Limited published literature has suggested that boric acid and borate-buffered MPS may alter the corneal epithelium; an effect attributed to cytotoxicity induced by boric acid. However, this claim has not been substantiated. We investigated the effect of treating cells with relevant concentrations of boric acid using two cytotoxicity assays, and also assessed the impact of boric acid on corneal epithelial barrier function by measuring TEER and immunostaining for tight junction protein ZO-1 in human corneal epithelial cells. Boric acid was also assessed in an in vivo ocular model when administered for 28 days. Additionally, we evaluated Biotrue multi-purpose solution, a novel borate-buffered MPS, alone and with contact lenses for ocular compatibility in vitro and in vivo. Boric acid passed both cytotoxicity assays and did not alter ZO-1 distribution or corneal TEER. Furthermore, boric acid was well-tolerated on-eye following repeated administration in a rabbit model. Finally, Biotrue multi-purpose solution demonstrated good ocular biocompatibility both in vitro and in vivo. This MPS was not cytotoxic and was compatible with the eye when administered alone and when evaluated with contact lenses. We demonstrate that boric acid and a borate-buffered MPS is compatible with the ocular environment. Our findings provide evidence that ocular effects reported for some borate-buffered MPS may be incorrectly attributed to boric acid and are more likely a function of the unique combination of ingredients in the MPS formulation tested. Copyright © 2010 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

16 CFR 315.1 - Scope of regulations in this part.

Code of Federal Regulations, 2010 CFR

2010-01-01

... CONTACT LENS RULE § 315.1 Scope of regulations in this part. This part, which shall be called the “Contact Lens Rule,” implements the Fairness to Contact Lens Consumers Act, codified at 15 U.S.C. 7601-7610, which requires that rules be issued to address the release, verification, and sale of contact lens...

Corneal epithelial and aqueous humor acidification during in vivo contact lens wear in rabbits.

PubMed

Giasson, C; Bonanno, J A

1994-03-01

Based on contact lens-induced stromal acidification of the cornea, it has been suggested that the corneal epithelial and endothelial cells also become acidotic during contact lens wear. This alleged acidification may have a role in altered cell appearance and metabolism during contact lens wear. This study investigated the effects of anoxia, carbon dioxide retention, and contact lens gas transmissibility on the epithelial and aqueous humor pH in living rabbits. Epithelial intracellular pH (pHi) and aqueous humor pH were fluorophotometrically measured with a pH sensitive-dye (BCECF) during contact lens wear or exposure to various gas mixtures. Polymethylmethacrylate (PMMA) lens wear acidified epithelial cells by preventing CO2 efflux and by inducing hypoxia. Increasing lens oxygen transmissibility decreased epithelial acidification. After initiation of rigid, gas-permeable (RGP) lens wear or CO2-air exposure, pHi dropped transiently and then recovered partially. This recovery of pHi was not observed during anoxia, whether induced by PMMA lens wear or exposure to 100% N2. The aqueous humor also acidified during PMMA lens wear, a phenomenon not observed during RGP lens wear. Changes in aqueous pH were smaller, slower, and delayed when compared to their epithelial counterparts. Hypoxic contact lens wear acidifies the corneal epithelium and aqueous humor. The aqueous humor pH change indicates a probable endothelial acidification during hypoxic contact lens wear; the pH changes are caused by two separate and additive effects, CO2 retention and hypoxic acidosis. Increases in the oxygen transmissibility of the lens decrease the cellular acidosis, which might minimize cellular complications arising from contact lens wear. We estimate that a lens with an oxygen transmissibility (Dk/L) of 300 x 10(-11) (cm/sec)(ml O2/ml x mm Hg) is needed to prevent epithelial pHi changes in the open eye. In contrast, lenses with Dk/L as low as 18 x 10(-9) (cm/sec)(ml O2/ml x mm Hg) can prevent aqueous humor pH changes.

Non-invasive pre-lens tear film assessment with high-speed videokeratoscopy.

PubMed

Llorens-Quintana, Clara; Mousavi, Maryam; Szczesna-Iskander, Dorota; Iskander, D Robert

2018-02-01

To evaluate the effect of two types of daily contact lenses (delefilcon A and omafilcon A) on the tear film and establish whether it is dependent on pre-corneal tear film characteristics using a new method to analyse high-speed videokeratoscopy recordings, as well as to determine the sensitivity of the method in differentiating between contact lens materials on eye. High-speed videokeratoscopy recordings were analysed using a custom made automated algorithm based on a fractal dimension approach that provides a set of parameters directly related to tear film stability. Fifty-four subjects participated in the study. Baseline measurements, in suppressed and natural blinking conditions, were taken before subjects were fitted with two different daily contact lenses and after four hours of contact lens wear. The method for analysing the stability of the tear film provides alternative parameters to the non-invasive break up time to assess the quality of the pre-corneal and pre-lens tear film. Both contact lenses significantly decreased the quality of the tear film in suppressed and natural blinking conditions (p<0.001). The utilised method was able to distinguish between contact lens materials on eye in suppressed blinking conditions. The pre-corneal tear film characteristics were not correlated with the decrease in pre-lens tear film quality. High-speed videokeratoscopy equipped with an automated method to analyse the dynamics of the tear film is able to distinguish between contact lens materials in vivo. Incorporating the assessment of pre-lens tear film to the clinical practice could aid improving contact lens fitting and understand contact lens comfort. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Dynamics of a pre-lens tear film after a blink: Model, evolution, and rupture

NASA Astrophysics Data System (ADS)

Usha, R.; Anjalaiah, Sanyasiraju, Y. V. S. S.

2013-11-01

A mathematical model is developed to investigate the dynamics and rupture of a pre-lens tear film on a contact lens. The contact lens is modeled as a saturated porous medium of constant, finite thickness and is described by the Darcy-Brinkman equations with stress-jump condition at the interface. The model incorporates the influence of capillarity, gravitational drainage, contact lens properties such as the permeability, the porosity, and the thickness of the contact lens on the evolution and rupture of a pre-lens tear film, when the eyelid has opened after a blink. Two models are derived for the evolution of a pre-lens tear film thickness using lubrication theory and are solved numerically; the first uses shear-free surface condition and the second, the tangentially immobile free surface condition. The results reveal that life span of a pre-lens tear film is longer on a thinner contact lens for all values of permeability and porosity parameter considered. An increase in permeability of contact lens, porosity or stress-jump parameter increases the rate of thinning of the film and advances the rupture time. The viscous-viscous interaction between the porous contact lens and the pre-lens tear film increases the resistance offered by the frictional forces to the rate of thinning of pre-lens tear film. This slows down the thinning process and hence delays the rupture of the film as compared to that predicted by the models of Nong and Anderson [SIAM. J. Appl. Math. 70, 2771-2795 (2010)] derived in the framework of Darcy model.

Contact lens-induced circumlimbal staining in silicone hydrogel contact lenses worn on a daily wear basis.

PubMed

Maïssa, Cécile; Guillon, Michel; Garofalo, Renee J

2012-01-01

The principal objective of the study was to measure the conjunctival staining produced in the circumlimbal region by silicone hydrogel contact lenses with different edge designs. The secondary objective was to investigate the association between circumlimbal staining and comfort. Four silicone hydrogel contact lenses: ACUVUE OASYS (knife edge design), AIR OPTIX, Biofinity (chisel edge rounded edge combination), and PureVision (rounded edge design), and 1 hydrogel contact lens, ACUVUE 2 (knife edge design), were tested. The study was conducted on a cohort population of 27 established soft contact lens wearers, who wore each contact lens type, in a random order, for a period of 10 (±2) days. Circumlimbal staining was measured in a double-masked fashion through image analysis of digital photographs of lissamine green taken under controlled experimental conditions. The results obtained showed that contact lens edge design was the primary factor controlling circumlimbal staining for silicone hydrogel lenses: a rounded edge away from the ocular surface produced the lowest staining (average, 0.19%) and a knife edge in close apposition to the ocular surface produced the highest staining (average, 1.34%). Contact lens material rigidity was also identified to affect circumlimbal staining and an inverse association between circumlimbal staining and contact lens comfort was demonstrated: the rounded edge design produced the lowest comfort (72 of 100) and the knife edge design produced the highest (87 out of 100). Soft contact lens wear induces circumlimbal staining, the level of staining being influenced by the contact lens edge design. However, high level of circumlimbal staining is not associated with decreased comfort.

Effect of internal lubricating agents of disposable soft contact lenses on higher-order aberrations after blinking.

PubMed

Koh, Shizuka; Maeda, Naoyuki; Hamano, Takashi; Hirohara, Yoko; Mihashi, Toshifumi; Hori, Yuichi; Hosohata, Jun; Fujikado, Takashi; Tano, Yasuo

2008-03-01

To investigate whether the polymer composition of disposable soft contact lenses affects sequential changes in higher-order aberrations (HOAs). Fifteen subjects who wore disposable soft contact lenses with dryness-related symptoms and 15 non-contact lens wearers were enrolled in this study. Ocular HOAs were measured for 60 seconds in each subject wearing a disposable etafilcon A lens (conventional lens) or a disposable etafilcon A lens with polyvinyl pyrrolidone (PVP) (lens with PVP) after 1 hour of contact lens wear. During the measurement, subjects were forced to blink every 10 seconds. The aberration data were analyzed in the central 4-mm diameter up to the sixth-order Zernike polynomials. Total HOAs, the fluctuation index (FI), and the stability index (SI) of the total HOAs over time were compared between the two groups. The subjective ocular dryness also was scored. In symptomatic wearers of disposable soft contact lenses, the total HOAs, the FI, and the SI with the lens with PVP were significantly (P=0.013, P=0.014, P=0.019, respectively) lower than with the conventional lens, whereas a significant (P=0.018) difference between the two lenses was observed only in the FI in non-contact lens wearers. Subjective ocular dryness with the lens with PVP significantly decreased compared with the conventional lens in both groups. Sequential measurement of HOAs may be a useful objective method to evaluate the effect of internal lubricating agents of disposable soft contact lenses on optical quality.

Effect of contact lens use on Computer Vision Syndrome.

PubMed

Tauste, Ana; Ronda, Elena; Molina, María-José; Seguí, Mar

2016-03-01

To analyse the relationship between Computer Vision Syndrome (CVS) in computer workers and contact lens use, according to lens materials. Cross-sectional study. The study included 426 civil-service office workers, of whom 22% were contact lens wearers. Workers completed the Computer Vision Syndrome Questionnaire (CVS-Q) and provided information on their contact lenses and exposure to video display terminals (VDT) at work. CVS was defined as a CVS-Q score of 6 or more. The covariates were age and sex. Logistic regression was used to calculate the association (crude and adjusted for age and sex) between CVS and individual and work-related factors, and between CVS and contact lens type. Contact lens wearers are more likely to suffer CVS than non-lens wearers, with a prevalence of 65% vs 50%. Workers who wear contact lenses and are exposed to the computer for more than 6 h day(-1) are more likely to suffer CVS than non-lens wearers working at the computer for the same amount of time (aOR = 4.85; 95% CI, 1.25-18.80; p = 0.02). Regular contact lens use increases CVS after 6 h of computer work. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

Treatment of contact lens related dry eye with antibacterial honey.

PubMed

Wong, Daniel; Albietz, Julie M; Tran, Huan; Du Toit, Cimonette; Li, Anita Hui; Yun, Tina; Han, Jee; Schmid, Katrina L

2017-12-01

Contact lens induced dry eye affects approximately 50% of contact lens wearers. The aim was to assess the effects of Manuka (Leptospermum sp.) honey eye drops (Optimel, Melcare, Australia) on dry eye in contact lens wearers. The safety of the honey eye drops in contact lens wear and contact lens wearers' compliance were also evaluated. Prospective, randomised, cross over study, examiner masked, pilot treatment trial. Twenty-four participants aged 20 to 55 years with contact lens related dry eye were recruited and randomised to two treatment groups; 20 completed the study. One group used Optimel eye drops twice a day for two weeks followed by conventional lubricant (Systane Ultra, Alcon) therapy for two weeks; the other group completed the treatments in the reverse order. Before and after each treatment dry eye symptomology, ocular surface inflammation, and tear quantity and quality were assessed. Participants completed a daily log detailing their usage of treatments and any issues. Dry eye symptoms improved significantly after Optimel treatment. Patients with more severe symptoms at baseline showed a greater improvement in symptoms. No significant differences were observed in the objective signs of dry eye; presumably because of the short treatment duration. Seventy-five% of contact lens wearers reported good adherence to Optimel treatment and 95% reported no issues using this product. Optimel Eye Drops reduce the symptoms of dry eye in contact lens wearers and are safe to use. A longer treatment period to assess the effect on clinical signs of dry eye is required. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Tear exchange and contact lenses: a review.

PubMed

Muntz, Alex; Subbaraman, Lakshman N; Sorbara, Luigina; Jones, Lyndon

2015-01-01

Tear exchange beneath a contact lens facilitates ongoing fluid replenishment between the ocular surface and the lens. This exchange is considerably lower during the wear of soft lenses compared with rigid lenses. As a result, the accumulation of tear film debris and metabolic by-products between the cornea and a soft contact lens increases, potentially leading to complications. Lens design innovations have been proposed, but no substantial improvement in soft lens tear exchange has been reported. Researchers have determined post-lens tear exchange using several methods, notably fluorophotometry. However, due to technological limitations, little remains known about tear hydrodynamics around the lens and, to-date, true tear exchange with contact lenses has not been shown. Further knowledge regarding tear exchange could be vital in aiding better contact lens design, with the prospect of alleviating certain adverse ocular responses. This article reviews the literature to-date on the significance, implications and measurement of tear exchange with contact lenses. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Contact lens wear is intrinsically inflammatory.

PubMed

Efron, Nathan

2017-01-01

Eye-care practitioners typically associate ocular inflammation during contact lens wear with serious complications such as microbial keratitis; however, more subtle mechanisms may be at play. This paper tests the notion that contact lens wear is intrinsically inflammatory by exploring whether uncomplicated contact lens wear meets the classical, clinical definition of inflammation - rubor (redness), calor (heat), tumor (swelling), dolor (pain) and functio laesa (loss of function) - as well as the contemporary, sub-clinical definition of inflammation (cellular and biochemical reactions). It is demonstrated that all of these clinical and sub-clinical criteria are met with hydrogel lens wear and most are met with silicone hydrogel lens wear, indicating that uncomplicated contact lens wear is intrinsically inflammatory. Consideration of both traditional and contemporary thinking about the role of inflammation in the human body leads to the perhaps surprising conclusion that the chronic, low grade, sub-clinical inflammatory status of the anterior eye during contact lens wear, which may be termed 'para-inflammation', is a positive, protective phenomenon, whereby up-regulation of the immune system, in a non-damaging way, maintains the eye in a state of 'heightened alert', ready to ward off any extrinsic noxious challenge. Characterisation of this inflammatory status may lead to the development of lens engineering or pharmacological strategies to modulate contact lens-induced inflammation, so as to render lens wear more safe and comfortable. © 2016 Optometry Australia.

Microbial Contamination of Contact Lenses, Lens Care Solutions, and Their Accessories: A Literature Review

PubMed Central

Szczotka-Flynn, Loretta B.; Pearlman, Eric; Ghannoum, Mahmoud

2012-01-01

Purpose A contact lens (CL) can act as a vector for microorganisms to adhere to and transfer to the ocular surface. Commensal microorganisms that uneventfully cohabitate on lid margins and conjunctivae and potential pathogens that are found transiently on the ocular surface can inoculate CLs in vivo. In the presence of reduced tissue resistance, these resident microorganisms or transient pathogens can invade and colonize the cornea or conjunctiva to produce inflammation or infection. Methods The literature was reviewed and used to summarize the findings over the last 30 years on the identification, enumeration, and classification of microorganisms adherent to CLs and their accessories during the course of normal wear and to hypothesize the role that these microorganisms play in CL infection and inflammation. Results Lens handling greatly increases the incidence of lens contamination, and the ocular surface has a tremendous ability to destroy organisms. However, even when removed aseptically from the eye, more than half of lenses are found to harbor microorganisms, almost exclusively bacteria. Coagulase-negative Staphylococci are most commonly cultured from worn lenses; however, approximately 10% of lenses harbor Gram-negative and highly pathogenic species, even in asymptomatic subjects. In storage cases, the incidence of positive microbial bioburden is also typically greater than 50%. All types of care solutions can become contaminated, including up to 30% of preserved products. Conclusions The process of CL-related microbial keratitis and inflammation is thought to be preceded by the presence or transfer or both of microorganisms from the lens to the ocular surface. Thus, this detailed understanding of lens-related bioburden is important in the understanding of factors associated with infectious and inflammatory complications. Promising mechanisms to prevent bacterial colonization on lenses and lens cases are forthcoming, which may decrease the incidence of microbially driven CL complications. PMID:20168237

Contact Lenses Wettability In Vitro: Effect of Surface-Active Ingredients

PubMed Central

Lin, Meng C.; Svitova, Tatyana F.

2010-01-01

Purpose To investigate the release of surface-active agents (surfactants) from unworn soft contact lenses and their influence on the lens surface wettability in vitro. Methods Surface tension (ST) of blister pack solutions was measured by pendant-drop technique. STs at the air-aqueous interface and contact angles (CAs) of four conventional and seven silicone hydrogel (SiH) soft contact lenses (SCLs) were evaluated in a dynamic-cycling regime using a modified captive-bubble tensiometer-goniometer. Measurements were performed immediately after removal from blister packs, and after soaking in a glass vial filled with a surfactant-free solution, which was replaced daily for one week. Lens surface wettability was expressed as adhesion energy (AE) according to Young’s equation. Results STs of all blister pack solutions were lower than the reference ST of pure water (72.5 mN/m), indicating the presence of surfactants. When lenses were depleted of surfactants by soaking, the STs of all studied lenses and advancing CAs of selected lenses increased (p < 0.001). Receding CAs of all studied lenses were 12° ± 5° and were not affected by the presence of surfactants. For most of the conventional lenses, the surface wettability was largely dependent on surfactants, and reduced significantly after surfactant depletion. In contrast, most SiH lenses exhibited stable and self-sustained surface wettability in vitro. Conclusions The manufacturer-added surfactants affected wetting properties of all studied SCLs, although to different degrees. PMID:20400924

Acceleration of the formation of biofilms on contact lens surfaces in the presence of neutrophil-derived cellular debris is conserved across multiple genera

PubMed Central

Patel, Naiya B.; Hinojosa, Jorge A.; Zhu, Meifang

2018-01-01

Purpose We have previously shown that invasive strains of Pseudomonas aeruginosa exploit the robust neutrophil response to form biofilms on contact lens surfaces and invade the corneal epithelium. The present study investigated the ability of multiple bacterial genera, all commonly recovered during contact lens–related infectious events, to adhere to and form biofilms on contact lens surfaces in the presence of neutrophils. Methods Five reference strains from the American Type Culture Collection were used: P. aeruginosa, Serratia marcescens, Stenotrophomonas maltophilia, Staphylococcus aureus, and Staphylococcus epidermidis. Each bacterial strain was incubated overnight with or without stimulated human neutrophils in the presence of an unworn contact lens. Standard colony counts and laser scanning confocal microscopy of BacLight-stained contact lenses were used to assess bacterial viability. Three-dimensional modeling of lens-associated biofilms with Imaris software was used to determine the biofilm volume. Lenses were further examined using scanning electron microscopy. Results Less than 1% of the starting inoculum adhered to the contact lens surface incubated with bacteria alone. There were no differences in adhesion rates to contact lens surfaces between bacteria in the absence of neutrophils for either the Gram-negative or Gram-positive test strains. Bacterial adhesion to contact lens surfaces was accelerated in the presence of human neutrophils for all test strains. This effect was least evident with S. epidermidis. There was also an increase in the number of viable bacteria recovered from contact lens surfaces (p<0.001 for the Gram-negative and Gram-positive test strains, respectively) and in biofilm volume (p<0.001 for the Gram-negative test strains, p = 0.005 for S. aureus). Conclusions These results show that in addition to P. aeruginosa, other bacteria commonly encountered during contact lens wear possess the capacity to utilize neutrophil-derived cellular debris to facilitate colonization of the lens surface. These data suggest that this phenomenon is conserved among multiple genera. Thus, during contact lens wear, the presence of inflammation and the accumulation of neutrophil debris under the posterior lens surface likely contribute to colonization of the lens. Further studies are needed to correlate these findings with risk for infection in an animal model. PMID:29422767

[Current quality management situation and administration countermeasure study of enterprises marketing corneal contact lens].

PubMed

Liu, Yungui; Yao, Ying; Shangguan, Shihao; Gu, Qun; Gao, Wuming; Chen, Yaoshui

2014-05-01

Study the current quality management situation of enterprises marketing corneal contact lens via systemic investigations and explore effective administration countermeasures in the future. The quality management indicators of sixty-two corneal contact lens marketing enterprises in Xuhui district of Shanghai were systematically investigated and enterprises of different operation models was compared and analyzed. Wholesale enterprises and retail chain enterprises are apparently better than independent enterprises almost in all facets. Facilitate market accession of corneal contact lens marketing enterprises, encourage the business model of retail chain, enhance supervision of corneal contact lens marketing enterprises, especially independent franchisors.

Impact of lens case hygiene guidelines on contact lens case contamination.

PubMed

Wu, Yvonne T; Teng, Yuu Juan; Nicholas, Mary; Harmis, Najat; Zhu, Hua; Willcox, Mark D P; Stapleton, Fiona

2011-10-01

Lens case contamination is a risk factor for microbial keratitis. The effectiveness of manufacturers' lens case cleaning guidelines in limiting microbial contamination has not been evaluated in vivo. This study compared the effectiveness of manufacturers' guidelines and an alternative cleaning regimen. A randomized cross-over clinical trial with two phases (n = 40) was performed. Participants used the lens types of their choice in conjunction with the provided multipurpose solution (containing polyhexamethylene biguanide) for daily wear. In the manufacturers' guideline phase, cases were rinsed with multipurpose solution and air dried. In the alternative regimen phase, cases were rubbed, rinsed with solution, tissue wiped, and air-dried face down. The duration of each phase was 1 month. Lens cases were collected at the end of each phase for microbiological investigation. The levels of microbial contamination were compared, and compliance to both regimens was assessed. The case contamination rate was 82% (32/39) in the manufacturers' guideline group, compared with 72% (28/39) in the alternative regimen group. There were significantly fewer (p = 0.004) colony forming units (CFU) of bacteria from cases used by following the alternative regimen (CFU range of 0 to 10, and median of 12 CFU per well) compared with that of the manufacturer's guidelines (CFU range of 0 to 10, and median of 28 CFU per well). The compliance level between both guidelines was not significantly different (p > 0.05). The alternative guidelines are more effective in eliminating microbial contamination from lens cases than that of the current manufacturer's guideline. Simply incorporating rubbing and tissue-wiping steps in daily case hygiene reduces viable organism contamination.

Quantification of individual proteins in silicone hydrogel contact lens deposits

PubMed Central

Zhao, Zhenjun; Zhu, Hua; Tilia, Daniel; Willcox, Mark D.P.

2013-01-01

Purpose The aim of this study was to quantify specific proteins deposited on daily wear silicone hydrogel lenses used in combination with multipurpose disinfecting solutions (MPDSs) by applying multiple-reaction-monitoring mass spectrometry (MRM-MS). Methods Balafilcon A or senofilcon A contact lenses used with different MPDSs on a daily wear schedule were collected. Each worn lens was extracted and then digested with trypsin. MRM-MS was applied to quantify the amounts of lysozyme, lactoferrin, lipocalin-1, proline-rich protein-4, and keratin-1 in the extracts. Results The amount of protein extracted from the contact lenses was affected by the individual wearers, lens material, and type of care system used. Higher amounts of proteins were extracted from lenses after wear when they were used with an MPDS containing polyhexamethylene biguanide (PHMB) and poloxamer 407 compared with MPDSs containing polyquaternium-1 (PQ-1)/alexidine dihydrochloride with Tetronic 904 or PQ-1/ PHMB with poloxamine and sulfobetaine (p<0.05). There was a correlation between the amount of lipocalin-1 or keratin-1 extracted from lenses and symptoms of ocular dryness. Conclusions The MRM-MS technique is a promising approach that could be used to reveal associations of individual proteins deposited on lenses with performance of contact lenses during wear. PMID:23441110

Surface thermodynamics and adhesion forces governing bacterial transmission in contact lens related microbial keratitis.

PubMed

Qu, Wenwen; Busscher, Henk J; Hooymans, Johanna M M; van der Mei, Henny C

2011-06-15

Contact lens induced microbial keratitis results from bacterial transmission from one surface to another. We investigated the adhesion forces of Pseudomonas aeruginosa, Staphylococci and Serratia to different contact lenses, lens cases and corneal surfaces using AFM, and applied a Weibull analysis on these adhesion forces to calculate bacterial transmission probabilities from lens case to corneas with a contact lens as an intermediate. Also a new surface thermodynamic parameter was introduced, the interfacial free energy of transmission, which in essence compares the interfacial free energies of bacterial adhesion, calculated from measured contact angles with liquids on the donating and receiving surfaces in the transmission process. Bacterial adhesion forces were generally strongest among all eight strains for the lens case (-6.5 to -12.0 nN) and corneas (-3.5 to -11.5 nN), while contact lenses (-0.6 to -13.1 nN) exerted slightly smaller adhesion forces. Consequently, bacterial transmission from lens case to contact lens yielded a smaller contribution in the final transmission than from contact lens to cornea. Bacterial transmission probabilities as derived from force analyses were higher when the interfacial free energies of transmission were more negative, which is in line with surface thermodynamic principles. Therewith this parameter could provide useful in analyzing other bacterial transmission phenomena between donating and receiving surfaces as well. Copyright © 2011 Elsevier Inc. All rights reserved.

Objective Assessment of Ocular Surface Response to Contact Lens Wear in Presbyopic Contact Lens Wearers of Asian Descent.

PubMed

Guillon, Michel; Dumbleton, Kathy; Theodoratos, Panagiotis; Patel, Trisha; Karkkainen, Tom; Moody, Kurt

2018-05-01

Contact lens wearers of Asian descent may be predisposed to experience microtrauma of the ocular surface as a result a thinner post-lens tear film and higher eyelid tension, and these effects would be anticipated to be most marked in an older population. The objective of this study was to quantify the mechanical effects of the study contact lenses on the ocular surface in a population of presbyopic contact lens wearers of Asian descent. Twenty established presbyopic contact lens wearers (hydrogel n=5, none habitual wearers of etafilcon A lenses; silicone hydrogel n=15) of Asian descent were refitted with etafilcon A multifocal daily disposable contact lenses (1-DAY ACUVUE MOIST MULTIFOCAL) for a period of 1 month of daily lens wear. The habitual modalities of wear were 45% daily disposable and 55% planned replacement. Digital photographs of the upper lid margins, nasal and temporal conjunctiva, and superior cornea were taken after 6 hr of wear of the participants' habitual contact lenses, after 1 day without contact lens wear, and after 6 hr of wear of the study contact lenses at the end of the 1-month period. The photographs were masked according to study visit and the staining extent measured using proprietary software. Lid margin staining was significantly lower with the study contact lenses (2.0±1.0 mm) than with the participants' own contact lenses (3.2±3.0 mm) after 6 hr of wear, representing a mean staining decrease of 38% (P=0.010). Lid margin staining after 6 hr of wear of the study contact lenses was not different from that measured after 1 day without contact lenses (P=0.507). Limbal staining was also significantly less with the study contact lenses than with the participants' own contact lenses after 6 hr of wear (P=0.009). There was minimal upper corneal staining, and the degree was similar with the study and habitual lenses. Etafilcon A material, worn under a daily disposable modality, was shown to reduce upper lid margin and limbal staining in presbyopic contact lens wearers of Asian descent compared with the wearers' own contact lenses. Because of the high preponderance of dry eye amongst presbyopes, material selection is of importance and consideration should be given to the lens-ocular surface interaction.

21 CFR 886.1385 - Polymethylmethacrylate (PMMA) diagnostic contact lens.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Polymethylmethacrylate (PMMA) diagnostic contact... Polymethylmethacrylate (PMMA) diagnostic contact lens. (a) Identification. A polymethylmethacrylate (PMMA) diagnostic contact lens is a device that is a curved shell of PMMA intended to be applied for a short period of time...

21 CFR 886.1385 - Polymethylmethacrylate (PMMA) diagnostic contact lens.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Polymethylmethacrylate (PMMA) diagnostic contact... Polymethylmethacrylate (PMMA) diagnostic contact lens. (a) Identification. A polymethylmethacrylate (PMMA) diagnostic contact lens is a device that is a curved shell of PMMA intended to be applied for a short period of time...

Oscillatory squeeze film analysis of soft contact lenses.

PubMed

Donnchadha, Éanna Mac; Leal, Cristina; Esmonde, Harry

2018-04-13

The complex modulus of a soft contact lens affects the optical performance, fitting, on-eye movement, wettability, physiological impact and overall comfort of the lens. However, despite acknowledgement that the mechanical behaviour of contact lenses is time-dependent, the rheological characteristics of contact lenses remain under-defined. While existing studies have focussed on elasticity to describe lens behaviour, this paper proposes using oscillatory squeeze film analysis to evaluate the complex modulus. The effects of excitation amplitude, repeatability and surface wetness are examined for four commercially available lenses. Slip at the lens/platen interface is considered along with bias introduced by pre-compressing the lens between platens. Test results when compared to results reported from other test methods indicate that a high degree of slip occurs at the lens platen interface suggesting that deformation is primarily due to biaxial extension. Copyright © 2018 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Effect of three months of soft contact lens wear on conjunctival cytology.

PubMed

Sapkota, Kishor; Franco, Sandra; Sampaio, Paula; Lira, Madalena

2016-07-01

The purpose of this study was to investigate the effect of three months of soft contact lens wear on conjunctival goblet cell density and epithelial cell morphology. This was a longitudinal clinical trial. Conjunctival impression cytology was performed on the superior palpebral conjunctiva in fifty-four eyes of twenty-seven neophyte contact lens wearers before and after three months of contact lens wear. Goblet cell density was determined by optical microscopy and epithelial cell morphology was classified according to the Tseng classification. Changes in goblet cell density as well as epithelial cell grading were determined. The effects of lens material and wearing modality on cytological changes were also investigated. Goblet cell density reduced significantly by 85 ± 151 cells/mm(2) (p < 0.001) after three months of contact lens wear. Reduction in goblet cell density was associated with lens materials; it was higher in conventional hydrogel lenses in comparison to silicone-hydrogel lenses (p = 0.008). The highest reduction in goblet cell density was found with Nelfilcon A lens wear (p = 0.002) and the lowest with Comfilcon A lens wear (p = 0.414). There was no statistically significant difference in grading of epithelial metaplasia before and after three months of contact lens wear (p = 0.075). Age was not correlated with the reduction in goblet cell density (r = -0.196, p = 0.160) but it was associated with the change in epithelial cell morphology (p = 0.036). Three months of soft contact lens wear statistically significantly reduced goblet cell density; however, no significant changes were found in the grading of epithelial metaplasia. Contact lenses with lower oxygen permeability, higher Young modulus and higher thickness highly affected the conjunctival cytology. © 2016 Optometry Australia.

Corneal oedema in a unilateral corneal graft patient induced by high Dk mini-scleral contact lens.

PubMed

Guillon, Natalie C; Godfrey, Andrew; Hammond, David S

2018-05-24

Scleral contact lenses are increasingly becoming accepted as the method of choice for visual correction of the irregular cornea. As such, cases have surfaced which demonstrate complications arising from mini-scleral lenses. Identification of these issues and adjusting fitting techniques accordingly is necessary for reducing the risks associated with mini-scleral lens wear. A 58 year old Caucasian female was referred for rigid gas permeable contact lens fitting for correction of right irregular astigmatism post penetrating keratoplasty. After four months of successful mini-scleral contact lens wear, the patient experienced a graft rejection episode and treated accordingly, then refit with a new mini-scleral lens. Five months after the lens refit, the patient presented with complaints of hazy vision, and a diagnosis of lens-induced corneal oedema made. Increased awareness of the potential complications of mini-scleral lenses is necessary to encourage and enforce mini-scleral lens fitting techniques that meet the requirements of minimum vault but adequate protection of the compromised cornea. Copyright © 2018 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Allergic manifestations of contact lens wearing.

PubMed

Solomon, Abraham

2016-10-01

Contact lens-induced papillary conjunctivitis (CLPC) is a common ocular allergic disease in contact lens wearers. In its more severe form, it can cause giant papillary conjunctivitis, resulting in contact lens intolerance and the need to discontinue the use of contact lenses. This review presents the pathogenesis, clinical manifestations and management guidelines of this common disorder. Different types of contact lenses are associated with differences in the severity of CLPC. Refitting patients with silicone hydrogel contact lenses or with daily disposable contact lenses may improve the signs and symptoms of CLPC. The recent introduction of the topical immunomodulatory agent tacrolimus in other severe allergic eye diseases may apply in suppressing the allergic inflammation in CLPC as well. CLPC is a common ocular disorder in contact lens wearers, with a significant impact on the quality of vision. It should be promptly recognized by healthcare practitioners and managed by modifications of the types and wearing schedules of contact lenses, as well as novel treatment options with topical immunomodulators.

A Class I UV-Blocking (senofilcon A) Soft Contact Lens Prevents UVA-induced Yellow Fluorescence and NADH loss in the Rabbit Lens Nucleus in vivo

PubMed Central

Giblin, Frank J.; Lin, Li-Ren; Simpanya, Mukoma F.; Leverenz, Victor R.; Fick, Catherine E.

2012-01-01

It is known that fluorescence, much of it caused by UVA light excitation, increases in the aging human lens, resulting in loss of sharp vision. This study used an in vivo animal model to investigate UVA-excited fluorescence in the rabbit lens, which contains a high level of the UVA chromophore NADH, existing both free and bound to λ-crystallin. Also, the ability of a Class I (senofilcon A) soft contact lens to protect against UVA-induced effects on the rabbit lens was tested. Rabbit eyes were irradiated with UVA light in vivo (100 mW/cm2 on the cornea) for 1 hour using monochromatic 365 nm light. Irradiation was conducted in the presence of either a senofilcon A contact lens, a minimally UV-absorbing lotrafilcon A contact lens, or no contact lens at all. Eyes irradiated without a contact lens showed blue 365 nm-excited fluorescence initially, but this changed to intense yellow fluorescence after 1 hour. Isolated, previously irradiated lenses exhibited yellow fluorescence originating from the lens nucleus when viewed under 365 nm light, but showed normal blue fluorescence arising from the cortex. Previously irradiated lenses also exhibited a faint yellow color when observed under visible light. The senofilcon A contact lens protected completely against the UVA-induced effects on fluorescence and lens yellowing, whereas the lotrafilcon A lens showed no protection. The UVA-exposure also produced a 53% loss of total NADH (free plus bound) in the lens nucleus, with only a 13% drop in the anterior cortex. NADH loss in the nucleus was completely prevented with use of a senofilcon A contact lens, but no significant protection was observed with a lotrafilcon A lens. Overall, the senofilcon A lens provided an average of 67% protection against UVA-induced loss of four pyridine nucleotides in four different regions of the lens. HPLC analysis with fluorescence detection indicated a nearly six-fold increase in 365 nm-excited yellow fluorescence arising from lens nuclear λ-crystallin after the in vivo UVA exposure. It is concluded that UVA-induced loss of free NADH (which fluoresces blue) may have allowed the natural yellow fluorescence of λ-crystallin and other proteins in the lens nucleus to become visible. Increased fluorescence exhibited by UVA-exposed λ-crystallin may have been the result of a UVA-induced change in the conformation of the protein occurring during the initial UVA-exposure in vivo. The results demonstrate the greater susceptibility of the lens nucleus to UVA-induced stress, and may relate to the formation of human nuclear cataract. The senofilcon A contact lens was shown to be beneficial in protecting the rabbit lens against effects of UVA light, including changes in fluorescence, increased yellowing and loss of pyridine nucleotides. PMID:22766154

A Class I UV-blocking (senofilcon A) soft contact lens prevents UVA-induced yellow fluorescence and NADH loss in the rabbit lens nucleus in vivo.

PubMed

Giblin, Frank J; Lin, Li-Ren; Simpanya, Mukoma F; Leverenz, Victor R; Fick, Catherine E

2012-09-01

It is known that fluorescence, much of it caused by UVA light excitation, increases in the aging human lens, resulting in loss of sharp vision. This study used an in vivo animal model to investigate UVA-excited fluorescence in the rabbit lens, which contains a high level of the UVA chromophore NADH, existing both free and bound to λ-crystallin. Also, the ability of a Class I (senofilcon A) soft contact lens to protect against UVA-induced effects on the rabbit lens was tested. Rabbit eyes were irradiated with UVA light in vivo (100 mW/cm(2) on the cornea) for 1 h using monochromatic 365 nm light. Irradiation was conducted in the presence of either a senofilcon A contact lens, a minimally UV-absorbing lotrafilcon A contact lens, or no contact lens at all. Eyes irradiated without a contact lens showed blue 365 nm-excited fluorescence initially, but this changed to intense yellow fluorescence after 1 h. Isolated, previously irradiated lenses exhibited yellow fluorescence originating from the lens nucleus when viewed under 365 nm light, but showed normal blue fluorescence arising from the cortex. Previously irradiated lenses also exhibited a faint yellow color when observed under visible light. The senofilcon A contact lens protected completely against the UVA-induced effects on fluorescence and lens yellowing, whereas the lotrafilcon A lens showed no protection. The UVA-exposure also produced a 53% loss of total NADH (free plus bound) in the lens nucleus, with only a 13% drop in the anterior cortex. NADH loss in the nucleus was completely prevented with use of a senofilcon A contact lens, but no significant protection was observed with a lotrafilcon A lens. Overall, the senofilcon A lens provided an average of 67% protection against UVA-induced loss of four pyridine nucleotides in four different regions of the lens. HPLC analysis with fluorescence detection indicated a nearly six-fold increase in 365 nm-excited yellow fluorescence arising from lens nuclear λ-crystallin after the in vivo UVA exposure. It is concluded that UVA-induced loss of free NADH (which fluoresces blue) may have allowed the natural yellow fluorescence of λ-crystallin and other proteins in the lens nucleus to become visible. Increased fluorescence exhibited by UVA-exposed λ-crystallin may have been the result of a UVA-induced change in the conformation of the protein occurring during the initial UVA-exposure in vivo. The results demonstrate the greater susceptibility of the lens nucleus to UVA-induced stress, and may relate to the formation of human nuclear cataract. The senofilcon A contact lens was shown to be beneficial in protecting the rabbit lens against effects of UVA light, including changes in fluorescence, increased yellowing and loss of pyridine nucleotides. Copyright © 2012 Elsevier Ltd. All rights reserved.

Crystal Structure of Chicken γS-Crystallin Reveals Lattice Contacts with Implications for Function in the Lens and the Evolution of the βγ-Crystallins.

PubMed

Sagar, Vatsala; Chaturvedi, Sumit K; Schuck, Peter; Wistow, Graeme

2017-07-05

Previous attempts to crystallize mammalian γS-crystallin were unsuccessful. Native L16 chicken γS crystallized avidly while the Q16 mutant did not. The X-ray structure for chicken γS at 2.3 Å resolution shows the canonical structure of the superfamily plus a well-ordered N arm aligned with a β sheet of a neighboring N domain. L16 is also in a lattice contact, partially shielded from solvent. Unexpectedly, the major lattice contact matches a conserved interface (QR) in the multimeric β-crystallins. QR shows little conservation of residue contacts, except for one between symmetry-related tyrosines, but molecular dipoles for the proteins with QR show striking similarities while other γ-crystallins differ. In γS, QR has few hydrophobic contacts and features a thin layer of tightly bound water. The free energy of QR is slightly repulsive and analytical ultracentrifugation confirms no dimerization in solution. The lattice contacts suggest how γ-crystallins allow close packing without aggregation in the crowded environment of the lens. Published by Elsevier Ltd.

In vitro power profiles of daily disposable contact lenses.

PubMed

Belda-Salmerón, Lurdes; Madrid-Costa, David; Ferrer-Blasco, Teresa; García-Lázaro, Santiago; Montés-Micó, Robert

2013-10-01

To evaluate and compare the distribution of refractive power within the optic zone of different soft contact lenses and to investigate the effect of lens decentration on the power profiles. The Nimo TR1504 instrument was used to measure the optical power across different aperture diameters (from 1.5mm to 5.5mm in steps of 0.5mm) of four daily disposable contact lenses: DAILIES TOTAL1, Proclear 1-Day, SofLens daily disposable and 1-DAY ACUVUE MOIST. Measurements were performed using a wet cell. Power data were evaluated when contact lenses were in its centered position and after inducing different amounts of lens decentration (from 0.2mm to 1.0mm in steps of 0.2mm). All contact lenses showed an increase - more negative - in lens power with distance from the lens center. The amount of change varied depending on the lens. It was about 10% of lens power for DAILIES TOTAL1 (-0.29diopters (D)), SofLens daily disposable (-0.36D), and Proclear 1-Day (-0.32D) whereas 1-DAY ACUVUE MOIST showed a percentage variation of 3.3% (-0.10D). After inducing a lens decentration up to 1mm, the power curves were shifted in the negative direction. However, the change obtained in lens power compared with well-centered position was always lower than a quarter of diopter both for all the lenses and aperture diameters. Our results showed a variation of the refractive power from the lens center, becoming more negative toward the periphery, with a negligible effect of the decentration for all disposable contact lenses studied. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Accounting for Ethnicity-Related Differences in Ocular Surface Integrity as a Step Toward Understanding Contact Lens Discomfort.

PubMed

Chan, Stefanie M; Svitova, Tatyana F; Lin, Meng C

2017-01-01

Contact lens discomfort is a common problem that can lead to unsuccessful or limited contact lens wear. Although many factors may contribute to contact lens discomfort, limited research has explored the influence of ethnicity-related differences in the anatomy and physiology of the ocular surface. Therefore, we performed a search of the literature in PubMed using key words related to "ocular surface" paired with the terms "race" and "ethnicity." The goal of this review was to determine potential areas of research regarding ethnicity differences, particularly between Asian and non-Asian eyes, in ocular surface integrity to advance our understanding of contact lens discomfort.

Contact lens rehabilitation following repaired corneal perforations

PubMed Central

Titiyal, Jeewan S; Sinha, Rajesh; Sharma, Namrata; Sreenivas, V; Vajpayee, Rasik B

2006-01-01

Background Visual outcome following repair of post-traumatic corneal perforation may not be optimal due to presence of irregular keratometric astigmatism. We performed a study to evaluate and compare rigid gas permeable contact lens and spectacles in visual rehabilitation following perforating corneal injuries. Method Eyes that had undergone repair for corneal perforating injuries with or without lens aspiration were fitted rigid gas permeable contact lenses. The fitting pattern and the improvement in visual acuity by contact lens over spectacle correction were noted. Results Forty eyes of 40 patients that had undergone surgical repair of posttraumatic corneal perforations were fitted rigid gas permeable contact lenses for visual rehabilitation. Twenty-four eyes (60%) required aphakic contact lenses. The best corrected visual acuity (BCVA) of ≥ 6/18 in the snellen's acuity chart was seen in 10 (25%) eyes with spectacle correction and 37 (92.5%) eyes with the use of contact lens (p < 0.001). The best-corrected visual acuity with spectacles was 0.20 ± 0.13 while the same with contact lens was 0.58 ± 0.26. All the patients showed an improvement of ≥ 2 lines over spectacles in the snellen's acuity chart with contact lens. Conclusion Rigid gas permeable contact lenses are better means of rehabilitation in eyes that have an irregular cornea due to scars caused by perforating corneal injuries. PMID:16536877

Contact Lens Anterior Surface pH

DTIC Science & Technology

1991-02-01

greenhouse effect and contact lenses, in Trans- 4. Nom MS: Tear fluid pH in normals, contact lens wearers, actions of the British Contact Lens...Invest 3. Fullard R), Carney LG: Diurnal variation in human tear en- Op/hdanmol Vis Sci 1978;17:810-813. ymes. Exp Eye Res 1984;38:15-26. 20. Efron N: The

Thermal Interaction of Contact Lens Eyewear and 94 GHz Ocular Exposures

DTIC Science & Technology

2008-09-01

AFRL-RH-BR-TR-2008-0071 ` Thermal Interaction of Contact Lens Eyewear and 94 GHz Ocular Exposures John D’Andrea Carrie C. Crane...THERMAL INTERACTION OF CONTACT LENS EYEWEAR AND 94 GHz OCULAR EXPOSURES D’Andrea JA 1, Crane CC1, Hatcher DJ1, Marchello DR1, Ziriax JM1...MM-YYYY) 12-20-2005 2. REPORT TYPE Technical Report 3. DATES COVERED (From - To) 2004-2005 THERMAL INTERACTION OF CONTACT LENS EYEWEAR AND 94

[Comparative analysis of visual function and the quality of life index with eyeglasses or a progressive contact lens].

PubMed

Sant'Anna, Neusa Vidal; Schor, Paulo; Lipener, César; Uras, Ricardo

2006-01-01

To compare the visual function and the answers to a questionnaire of quality of life of patients wearing a progressive contact lens or eyeglasses. The Focus Progressive contact lens had been fitted in 35 patients with far visual acuity with progressive-addition eyeglasses equal to zero (log MAR) and near J1 (Jaeger). The far and near visual acuities and the measurement of contrast sensitivity were compared when the patients were wearing the eyeglasses or the contact lens and the patients' results of the scores of the quality of life questionnaire (NEI VFQ-25) were analyzed statistically considering the type of ametropy and the age. The far and near visual acuities and the contrast sensitivity measurement were worse with the contact lens than with eyeglasses. The answers to the questionnaire did not differ when were comparing the same patients wearing eyeglasses or contact lens, no matter the type of ametropy. The myopic and the hyperopic subgroups had worse answers to the quality of life questionnaire when corrected with the contact lens than with eyeglasses, both with age equal to or less than their median. The visual function was worse with the contact lens. The type of ametropy did not influence the answers to the quality of life questionnaire considering the optical correction, but age did.

Clinical benefits of a new multipurpose disinfecting solution in silicone hydrogel and soft contact lens users.

PubMed

Campbell, Robert; Kame, Gregory; Leach, Norman; Paul, Matthew; White, Eric; Zigler, Lamar

2012-03-01

To evaluate the safety and efficacy of a new multipurpose disinfecting solution (MPDS) containing a diblock copolymer, poly(oxyethylene)-poly(oxybutylene), designed to improve the wetting properties of silicone-hydrogel lenses. This 90-day, randomized, concurrently controlled, double-masked, multisite study involved 573 subjects at 30 investigational sites in the United states. Existing lens wearers were randomly assigned to either regimen 1 (OPTI-FREE PureMoist, a newly developed formulation, Alcon Laboratories Inc., Fort Worth, TX) or regimen 2 (renu fresh, Bausch and Lomb Inc., Rochester, NY). At baseline, days 7, 30, 60, and 90, the subjects recorded subjective evaluations relating to lens acceptability and comfort, wearing time, and rewetting drop frequency, whereas investigators assessed slitlamp findings (including corneal fluorescein staining), lens deposits (modified Rudko), visual acuity, and adverse events. Group IV lenses were collected for ex vivo measurement of lysozyme deposits. Differences favoring regimen 1 were noted on day 90 for subjective evaluations of lens comfort (insertion, removal, overall); lens moisture and freshness; gentle on eye; clear vision; and lens handling (all P<0.004). Corneal fluorescein staining severity and area and lysozyme deposits (group IV lenses) were lower with regimen 1 (P<0.0001). This 90-day study shows that the new MPDS designed for silicone-hydrogel lenses is safe and effective when used by both silicone-hydrogel and traditional soft lens wearers. By improving comfort and decreasing lysozyme deposits and corneal fluorescein staining, the new MPDS enhances patients' wearing experience and helps maintain optimal lens performance.

On- and off-eye spherical aberration of soft contact lenses and consequent changes of effective lens power.

PubMed

Dietze, Holger H; Cox, Michael J

2003-02-01

Soft contact lenses produce a significant level of spherical aberration affecting their power on-eye. A simple model assuming that a thin soft contact lens aligns to the cornea predicts that these effects are similar on-eye and off-eye. The wavefront aberration for 17 eyes and 33 soft contact lenses on-eye was measured with a Shack-Hartmann wavefront sensor. The Zernike coefficients describing the on-eye spherical aberration of the soft contact lens were compared with off-eye ray-tracing results. Paraxial and effective lens power changes were determined. The model predicts the on-eye spherical aberration of soft contact lenses closely. The resulting power change for a +/- 7.00 D spherical soft contact lens is +/- 0.5 D for a 6-mm pupil diameter and +/- 0.1 D for a 3-mm pupil diameter. Power change is negligible for soft contact lenses corrected for off-eye spherical aberration. For thin soft contact lenses, the level of spherical aberration and the consequent power change is similar on-eye and off-eye. Soft contact lenses corrected for spherical aberration in air will be expected to be aberration-free on-eye and produce only negligibly small power changes. For soft contact lenses without aberration correction, for higher levels of ametropia and large pupils, the soft contact lens power should be determined with trial lenses with their power and p value similar to the prescribed lens. The benefit of soft contact lenses corrected for spherical aberration depends on the level of ocular spherical aberration.

Association Between Contact Lens Discomfort and Pre-lens Tear Film Kinetics.

PubMed

Guillon, Michel; Dumbleton, Kathryn A; Theodoratos, Panagiotis; Wong, Stephanie; Patel, Kishan; Banks, Gaidig; Patel, Trisha

2016-08-01

The relationship between contact lens wettability and comfort has been extensively evaluated; however, a direct correlation between the characteristics of the pre-lens tear film and the symptoms associated with contact lens discomfort has yet to be established. In addition, there is relatively limited knowledge relating to the entire tear film kinetics during the inter-blink period in contact lens wearers. The purpose of this analysis was to identify the characteristics of the pre-lens tear film kinetics that may be associated with the symptoms of contact lens discomfort. The study population comprised 202 soft (hydrogel and silicone hydrogel) contact lens wearers attending pre-screening visits at the OTG-i research clinic. All participants completed the Ocular Surface Disease Index (OSDI) questionnaire and the tear film was quantified via post hoc, masked analysis of high definition digital Tearscope videos recorded at the visit. The tear film kinetics of the least symptomatic wearers (OSDI lowest quintile scores, n = 45) were compared to the tear film kinetics of the most symptomatic wearers (OSDI highest quintile scores, n = 43). The hypothesis tested was that the tear film kinetics of asymptomatic wearers were better than tear film kinetics of symptomatic wearers. The distribution of lens types worn was as follows: Daily Disposable 46.5%, 1-Month Replacement 39.6%, and 2-Week Replacement 13.6%. 48.2% of lenses were silicone hydrogel and 51.8% hydrogel. Symptomatic wearers had a shorter break-up time (4.7 s vs. 6.0 s; p = 0.003), lesser surface coverage by the tear film during the interblink period (95.1% vs. 98.5%; p < 0.001) and greater surface exposure at the time of the blink (9.4% vs. 3.9%; p = 0.001). The current study demonstrated that the tear film kinetics of asymptomatic and symptomatic contact lens wearers were different, the findings supporting the hypothesis of poorer tear film kinetics for symptomatic than asymptomatic wearers in a general contact lens wearing population.

Ocular surface and tear film status among contact lens wearers and non-wearers who use VDT at work: comparing three different lens types.

PubMed

Tauste, Ana; Ronda, Elena; Baste, Valborg; Bråtveit, Magne; Moen, Bente E; Seguí Crespo, María-Del-Mar

2018-04-01

To analyze differences in the ocular surface appearance and tear film status of contact lens wearers and non-wearers in a group of visual display terminals (VDT) workers and additionally to assess differences between lens materials. Cross-sectional study of 236 office workers, of whom 92 were contact lens wearers. Workers provided information on their contact lenses (conventional hydrogel, silicone hydrogel or rigid gas permeable lenses) and exposure to VDT at work. Ocular surface and tear film status were determined by the presence of bulbar, limbal and lid redness, lid roughness and corneal staining type, and by Schirmer's and tear break-up time tests (TBUT). A generalized linear model was used to calculate the crude (cRR) and age- and sex-adjusted (aRR) relative risk to measure the association between ocular surface and tear film abnormalities and contact lens use and type. The aRR of ocular surface abnormalities was higher in contact lens wearers compared to non-wearers: bulbar redness (aRR 1.69; 95% CI 1.25-2.30), limbal redness (aRR 2.87; 1.88-4.37), lid redness (aRR 2.53; 1.35-4.73) and lid roughness (aRR 7.03; 1.31-37.82). VDT exposure > 4 h/day increased wearers' risk of limbal and lid redness. Conventional hydrogel wearers had the highest risk of ocular surface abnormalities, followed by silicone hydrogel wearers. Both contact and non-contact lens wearers had a high prevalence of altered TBUT (77.3 and 75.7% respectively) and Schirmer (51.8 and 41.3%). Regular contact lens use during VDT exposure at work increases risk of bulbar, limbal and lid redness, and lid roughness, especially in soft contact lens wearers. The high prevalence of altered TBUT and Schirmer's results in all participants suggests that VDT use greatly affects tear film characteristics.

Contact lens management of irregular corneas after traumatic aphakia: A pediatric case series.

PubMed

Aung, Yin-Yin; McLeod, Andrew

2015-10-01

Pediatric patients account for 35% of all cases that present after ocular trauma and 20.9% of those result in a ruptured globe. When repairing the globe, the removal of the natural lens results in a significant change in refractive error and loss of accommodation. In addition, the eye can have scarring, irregular astigmatism, and changes to the ocular surface. Treatment and vision rehabilitation should be aggressive and done quickly to prevent amblyopia. Advanced lens designs are often needed to treat both the irregular ocular surface and the aphakia. Treatment options are often confounded with the usual issues of contact lens compliance, intolerance, and complications. This case series follows three aphakic pediatric patients through the contact lens fitting process after sustaining a ruptured globe that left them aphakic with residual irregular astigmatism and corneal scarring. Patient 1 is a 3-year-old Hispanic male fit with a bitoric gas permeable contact lens with irregular astigmatism and an elevated central corneal scarring. Patient 2 is a 12-year-old Caucasian male with minimal residual astigmatism fit in a multifocal soft contact lens. Patient 3 is an 8-year-old African American male fit with a hybrid contact lens that was needed to vault the irregular astigmatism and central corneal scarring. Treating patients with irregular corneas or aphakia can be challenging in their own right, but in combination are some of the most advanced specialty contact lens fittings. This case series followed three pediatric patients through the fitting process and demonstrated the options and challenges when fitting this unique patient population. Copyright © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Comparison of adverse events with daily disposable hydrogels and spectacle wear: results from a 12-month prospective clinical trial.

PubMed

Sankaridurg, Padmaja R; Sweeney, Deborah F; Holden, Brien A; Naduvilath, Thomas; Velala, Indira; Gora, Rashmi; Krishnamachary, Murali; Rao, Gullapalli N

2003-12-01

To evaluate the type and incidence of adverse events seen with daily disposable hydrogel contact lens wear compared with a control (spectacle) group over 12 months. Prospective, randomized, observer-masked, comparative clinical trial. Two hundred eighty-one myopes with no prior contact lens wear experience were enrolled from August to December 1996. Subjects were 16 to 35 years old and had refractive errors ranging from a -0.75-diopter (D) sphere to a -6.00-D sphere with a cylinder less than -1.00 D. Each subject was randomly assigned to wear either bilateral disposable hydrogels on a daily disposable wear schedule or spectacles. Type and incidence of adverse events from each group. Adverse events were categorized as serious, significant, and nonsignificant based on the potential to cause vision impairment, severity at event, and level of clinical concern. At baseline, 1.6% of eyes had asymptomatic infiltrates that were nonsignificant. During the study, asymptomatic infiltrates were seen in both contact lens and spectacle groups at 20.5 events versus 11.3 events per 100 eyes per year of wear. No significant events were seen with the spectacle group. With the contact lens group, the type and incidence of significant events per 100 eyes per year of lens wear were corneal peripheral ulcer, 2.5 events; infiltrative keratitis, 1.5 events; and papillary conjunctivitis, 1 event. The incidence of both significant and nonsignificant events was greater with the contact lens group (P<0.05). No serious events (i.e., microbial keratitis) were seen in either group. A greater number of subjects were lost to follow-up or permanently discontinued from the contact lens group relative to the spectacle group (33% vs. 17%, P = 0.002). Lens-related problems such as dryness, discomfort, and difficulty with insertion and removal accounted for 27% of discontinuations from the contact lens group. Poor compliance (40%) was the greatest reason for discontinuations from the spectacle group. No clinically serious events were seen with either group. Only a small percentage of contact lens-wearing eyes presented with significant events, which is promising for daily disposable lens wear. Far more contact lens subjects were lost to follow-up or discontinued. Small, asymptomatic, subepithelial corneal infiltrates of unknown significance were seen in both contact lens- and spectacle-wearing eyes.

Microbiological Investigations of ReNu Plastic Bottles and the 2004 to 2006 ReNu With MoistureLoc-Related Worldwide Fusarium Keratitis Event.

PubMed

Bullock, John D; Warwar, Ronald E; Elder, B Laurel; Khamis, Harry J

2016-05-01

The purposes of this study were to determine whether the contact lens solution RevitaLens Ocutec (containing the antimicrobial agents alexidine and polyquaternium-1) would inhibit Fusarium organisms when heated in ReNu plastic bottles; whether alexidine would inhibit Fusarium organisms when heated in non-ReNu plastic bottles; and whether an alexidine-neutralizing compound leaches from heated ReNu bottles. RevitaLens and an alexidine solution (0.00045%), previously stored in ReNu bottles at room temperature (RT) and 56°C, were incubated with 7 different Fusarium organisms. The alexidine solution was similarly stored in seven non-ReNu plastic bottles and incubated with these same organisms. To determine if an alexidine-neutralizing compound might be leaching from heated ReNu bottles, phosphate-buffered saline (PBS) was incubated at RT and 56°C in ReNu bottles, combined with alexidine, and then tested for anti-Fusarium capability. After being heated in ReNu bottles, RevitaLens retained its anti-Fusarium capability, whereas the alexidine solution did not. The alexidine solution heated in seven non-ReNu plastic bottles retained its anti-Fusarium capability. The alexidine solution retained its anti-Fusarium capability when incubated with a PBS solution that had been heated in ReNu bottles, indicating, microbiologically, that an alexidine-neutralizing compound did not leach from the heated ReNu bottle. Alexidine uniquely fails to inhibit Fusarium organisms when heated in a plastic ReNu bottle, but not in seven other plastic bottles, whereas the anti-Fusarium capability of RevitaLens (containing the antimicrobial agents alexidine and polyquaternium-1) is unaffected by heating in a ReNu bottle. There does not seem to be an alexidine-neutralizing compound leaching from heated ReNu bottles. An interaction between alexidine and its heated ReNu bottle may have been a critical factor in the worldwide ReNu with MoistureLoc-related Fusarium keratitis event of 2004 to 2006.

Objective Assessment of Ocular Surface Response to Contact Lens Wear in Presbyopic Contact Lens Wearers of Asian Descent

PubMed Central

Dumbleton, Kathy; Theodoratos, Panagiotis; Patel, Trisha; Karkkainen, Tom; Moody, Kurt

2018-01-01

Introduction: Contact lens wearers of Asian descent may be predisposed to experience microtrauma of the ocular surface as a result a thinner post-lens tear film and higher eyelid tension, and these effects would be anticipated to be most marked in an older population. The objective of this study was to quantify the mechanical effects of the study contact lenses on the ocular surface in a population of presbyopic contact lens wearers of Asian descent. Methods: Twenty established presbyopic contact lens wearers (hydrogel n=5, none habitual wearers of etafilcon A lenses; silicone hydrogel n=15) of Asian descent were refitted with etafilcon A multifocal daily disposable contact lenses (1-DAY ACUVUE MOIST MULTIFOCAL) for a period of 1 month of daily lens wear. The habitual modalities of wear were 45% daily disposable and 55% planned replacement. Digital photographs of the upper lid margins, nasal and temporal conjunctiva, and superior cornea were taken after 6 hr of wear of the participants' habitual contact lenses, after 1 day without contact lens wear, and after 6 hr of wear of the study contact lenses at the end of the 1-month period. The photographs were masked according to study visit and the staining extent measured using proprietary software. Results: Lid margin staining was significantly lower with the study contact lenses (2.0±1.0 mm2) than with the participants' own contact lenses (3.2±3.0 mm2) after 6 hr of wear, representing a mean staining decrease of 38% (P=0.010). Lid margin staining after 6 hr of wear of the study contact lenses was not different from that measured after 1 day without contact lenses (P=0.507). Limbal staining was also significantly less with the study contact lenses than with the participants' own contact lenses after 6 hr of wear (P=0.009). There was minimal upper corneal staining, and the degree was similar with the study and habitual lenses. Conclusions: Etafilcon A material, worn under a daily disposable modality, was shown to reduce upper lid margin and limbal staining in presbyopic contact lens wearers of Asian descent compared with the wearers' own contact lenses. Because of the high preponderance of dry eye amongst presbyopes, material selection is of importance and consideration should be given to the lens–ocular surface interaction. PMID:27755285

Customer loyalty among daily disposable contact lens wearers.

PubMed

Patel, Neelam I; Naroo, Shehzad A; Eperjesi, Frank; Rumney, Nicholas J

2015-02-01

Optometric practices offer contact lenses as cash sale items or as part of monthly payment plans. With the contact lens market becoming increasingly competitive, patients are opting to purchase lenses from supermarkets and Internet suppliers. Monthly payment plans are often implemented to improve loyalty. This study aimed to compare behavioural loyalty between monthly payment plan members and non-members. BBR Optometry Ltd offers a monthly payment plan (Eyelife™) to their contact lens wearers. A retrospective audit of 38 Eyelife™ members (mean±SD: 42.7±15.0 years) and 30 non-members (mean±SD: 40.8±16.7 years) was conducted. Revenue and profits generated, service uptake and product sales between the two groups were compared over a fixed period of 18 months. Eyelife™ members generated significantly higher professional fee revenue (P<0.001), £153.96 compared to £83.50, and profits (P<0.001). Eyelife™ members had a higher uptake of eye examinations (P<0.001). The 2 groups demonstrated no significant difference in spectacle sales by volume (P=0.790) or value (P=0.369). There were also no significant differences in contact lens revenue (P=0.337), although Eyelife™ members did receive a discount. The Eyelife™ group incurred higher contact lens costs (P=0.037), due to a greater volume of contact lens purchases, 986 units compared to 582. Monthly payment plans improve loyalty among contact lens wearers, particularly service uptake and volume of lens purchases. Additionally the greater professional fees generated, render monthly payment plans an attractive business model and practice builder. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Evaluation of safety and efficacy of a new multipurpose disinfecting solution on silicone hydrogel contact lenses☆

PubMed Central

Pinto-Fraga, José; Blázquez Arauzo, Francisco; Urbano Rodríguez, Rubén; González-García, María J.

2014-01-01

Purpose To evaluate the safety and efficacy of a new multipurpose disinfecting solution (MPDS) with a formulation that includes aloe vera on its composition. Methods This is a prospective, randomized, double-masked clinical trial with a crossover design that included seven examinations. Two different MPDSs, Avizor Alvera® (study solution) and All Clean Soft® (control solution), each were used for 1 month. Comfilcon A silicone hydrogel contact lenses were used during the trial. The main outcome variables were corneal staining and deposits on the surfaces of the contact lenses. Other parameters including ocular surface response, contact lens wettability, user satisfaction, and adverse events, were analyzed according to the International Organization for Standardization (ISO) 11980:2010 guidance for clinical investigation. Results Twenty subjects (10 women, 10 men) (mean age, 27.7 ± 5.6 years; range, 20–41) were included. No differences between both MPDSs were found in the percentage of subjects with corneal staining >0 at day 30 (study: 35%, control: 50%; p = 0.46); neither in the percentage of subjects with deposits on the surface of the contact lens >0 at day 30 (study: 26.32%, control: 52.63%; p = 0.18). The study MPDS received higher rates in comfort (study: 8.14 ± 1.09, control: 7.94 ± 0.92; p = 0.56) and satisfaction at day 30 (study: 8.63 ± 0.91, control: 8.29 ± 0.80; p = 0.19), however the scores were not significantly different with the control MPDS. Conclusions The clinical trial showed that the study MPDS is safe, efficient, and has acceptable physiologic tolerance, according to the ISO 11980:2010 guidance for clinical investigation. PMID:25649640

Trends in the use of silicone hydrogel contact lenses for daily wear.

PubMed

Efron, Nathan; Morgan, Philip B

2008-10-01

Although the first silicone hydrogel contact lenses introduced onto the world contact lens market in 1999 held approval for both daily wear and extended wear use, the latter modality was promoted much more heavily by the manufacturers. The first silicone hydrogel lenses specifically promoted for daily wear were introduced in 2003. Data that we have gathered from annual contact lens fitting surveys demonstrate an immediate increase in market share whereby this lens type now represents more than one-third of soft lens fits in the United Kingdom. The success of this lens category is attributed to the health and safety benefits of silicone hydrogel materials and the positive impact of lens manufacturers by way of the effective marketing and distribution of these products.

Peripheral Optics with Bifocal Soft and Corneal Reshaping Contact Lenses

PubMed Central

Ticak, Anita; Walline, Jeffrey J.

2012-01-01

Purpose To determine whether bifocal soft contact lenses with a distance center design provide myopic defocus to the peripheral retina similar to corneal reshaping contact lenses. Methods Myopic subjects underwent five cycloplegic autorefraction readings centrally and at 10, 20, and 30 degrees temporally, nasally, superiorly, inferiorly while wearing a Proclear Multifocal “D” contact lens with a +2.00 D add (CooperVision, Fairport, NY) and after wearing a Corneal Refractive Therapy (Paragon Vision Sciences, Mesa, AZ) contact lens for two weeks Results Fourteen subjects completed the study. Nine (64%) were female, and 12 (86%) were Caucasian. The average (± standard deviation) spherical equivalent non-cycloplegic manifest refraction for the right eye was −2.84 ± 1.29 D. The average logMAR best-corrected, binocular high contrast visual acuity was −0.17 ± 0.15 while wearing the bifocal soft contact lens, and −0.09 ± 0.16 following corneal reshaping contact lens wear (ANOVA, p = 0.27). The orthokeratology contact lens yielded a more myopic peripheral optical profile than the soft bifocal contact lens at 20 and 30 degrees eccentricity (except inferior at 20 degrees); the two modalities were similar at 10 degrees eccentricity. Conclusions Our data suggest that the two modalities are dissimilar despite the statistical similarities. The corneal reshaping contact lens shows an increase in relative peripheral myopic refraction, a pattern achieved by other studies, but the bifocal lens does not exhibit such a pattern. The low statistical power of the study could be a reason for a lack of providing statistical difference in other positions of gaze, but the graphical representation of the data shows a marked difference in peripheral optical profile between the two modalities. More sophisticated methods of measuring the peripheral optical profile may be necessary to accurately compare the two modalities and to determine the true optical effect of the bifocal soft contact lens on the peripheral retina. PMID:23222924

Disinfection efficacy of contact lens care solutions against ocular pathogens.

PubMed

Miller, M J; Callahan, D E; McGrath, D; Manchester, R; Norton, S E

2001-01-01

Three commercially available products labeled as multi-purpose contact lens solutions, one multi-purpose disinfecting solution, and a hydrogen peroxide system were evaluated for antimicrobial activity according to the current International Organization for Standardization (ISO) and the U.S. Food and Drug Administration (FDA) stand-alone procedure for disinfecting products. One multi-purpose solution was selected to assess its antimicrobial activity against two human corneal isolates of Pseudomonas aeruginosa. Products were challenged with bacteria and fungi, and following a specified period, aliquots of inoculated test solution were neutralized and plated on validated recovery media. After incubation the number of viable microorganisms was enumerated and mean log reductions determined. ReNu MultiPlus (Bausch & Lomb, Rochester, NY), AOSEPT (CIBA Vision Corporation, Duluth, GA), and Opti-Free Express with Aldox (Alcon Laboratories, Ft. Worth, TX) were the only lens care products that met the stand-alone criteria for all required microorganisms within their minimum recommended disinfection time. Of these, ReNu MultiPlus provided the greatest overall antimicrobial activity. ReNu MultiPlus demonstrated a significantly higher mean log reduction of Staphylococcus aureus and Serratia marcescens than Opti-Free Express. ReNu MultiPlus also gave a higher mean log reduction of S. aureus and S. marcescens than AOSEPT, and a higher mean log reduction of Candida albicans and Fusarium solani than AOSEPT, Complete Comfort Plus (Allergan, Irivine, CA), and Solo-Care (CIBA Vision Corp.) (at 4 hours). Both Complete Comfort Plus and Solo-Care (at 4 hours) met the primary acceptance criteria for bacteria; however, neither product possessed enough antimicrobial activity to meet the minimum criteria for yeast or mold. ReNu Multiplus was effective against corneal isolates of P. aeruginosa. ReNu MultiPlus, AOSEPT, and Opti-Free Express met the requirements of the stand-alone primary criteria for disinfecting solutions. ReNu MultiPlus demonstrated the greatest overall disinfection efficacy, as well as excellent activity against clinical strains of P. aeruginosa.

Soft, smart contact lenses with integrations of wireless circuits, glucose sensors, and displays

PubMed Central

Park, Jihun; Kim, Joohee; Kim, So-Yun; Cheong, Woon Hyung; Jang, Jiuk; Park, Young-Geun; Na, Kyungmin; Kim, Yun-Tae; Heo, Jun Hyuk; Lee, Chang Young; Lee, Jung Heon; Bien, Franklin; Park, Jang-Ung

2018-01-01

Recent advances in wearable electronics combined with wireless communications are essential to the realization of medical applications through health monitoring technologies. For example, a smart contact lens, which is capable of monitoring the physiological information of the eye and tear fluid, could provide real-time, noninvasive medical diagnostics. However, previous reports concerning the smart contact lens have indicated that opaque and brittle components have been used to enable the operation of the electronic device, and this could block the user’s vision and potentially damage the eye. In addition, the use of expensive and bulky equipment to measure signals from the contact lens sensors could interfere with the user’s external activities. Thus, we report an unconventional approach for the fabrication of a soft, smart contact lens in which glucose sensors, wireless power transfer circuits, and display pixels to visualize sensing signals in real time are fully integrated using transparent and stretchable nanostructures. The integration of this display into the smart lens eliminates the need for additional, bulky measurement equipment. This soft, smart contact lens can be transparent, providing a clear view by matching the refractive indices of its locally patterned areas. The resulting soft, smart contact lens provides real-time, wireless operation, and there are in vivo tests to monitor the glucose concentration in tears (suitable for determining the fasting glucose level in the tears of diabetic patients) and, simultaneously, to provide sensing results through the contact lens display. PMID:29387797

Soft, smart contact lenses with integrations of wireless circuits, glucose sensors, and displays.

PubMed

Park, Jihun; Kim, Joohee; Kim, So-Yun; Cheong, Woon Hyung; Jang, Jiuk; Park, Young-Geun; Na, Kyungmin; Kim, Yun-Tae; Heo, Jun Hyuk; Lee, Chang Young; Lee, Jung Heon; Bien, Franklin; Park, Jang-Ung

2018-01-01

Recent advances in wearable electronics combined with wireless communications are essential to the realization of medical applications through health monitoring technologies. For example, a smart contact lens, which is capable of monitoring the physiological information of the eye and tear fluid, could provide real-time, noninvasive medical diagnostics. However, previous reports concerning the smart contact lens have indicated that opaque and brittle components have been used to enable the operation of the electronic device, and this could block the user's vision and potentially damage the eye. In addition, the use of expensive and bulky equipment to measure signals from the contact lens sensors could interfere with the user's external activities. Thus, we report an unconventional approach for the fabrication of a soft, smart contact lens in which glucose sensors, wireless power transfer circuits, and display pixels to visualize sensing signals in real time are fully integrated using transparent and stretchable nanostructures. The integration of this display into the smart lens eliminates the need for additional, bulky measurement equipment. This soft, smart contact lens can be transparent, providing a clear view by matching the refractive indices of its locally patterned areas. The resulting soft, smart contact lens provides real-time, wireless operation, and there are in vivo tests to monitor the glucose concentration in tears (suitable for determining the fasting glucose level in the tears of diabetic patients) and, simultaneously, to provide sensing results through the contact lens display.

Contact Lens Risks

MedlinePlus

... Health and Consumer Devices Consumer Products Contact Lenses Contact Lens Risks Share Tweet Linkedin Pin it More ... redness blurred vision swelling pain Serious Hazards of Contact Lenses Symptoms of eye irritation can indicate a ...

Microbial Keratitis in Kingdom of Bahrain: Clinical and Microbiology Study

PubMed Central

Al-Yousuf, Nada

2009-01-01

Background: Microbial keratitis is a potentially vision threatening condition worldwide. Knowing the predisposing factors and etiologic microorganism can help control and prevent this problem. This is the first study of its kind in Kingdom of Bahrain. Objective: To study the profile of microbial keratitis in Bahrain with special focus on risk factors, clinical outcome and microbilogical results. Methods: A retrospective analysis of all patients admitted in Salmaniya Medical Complex over a period of three years from January 2005 to January 2007 was performed. A total of 285 patients with keratitis were analysed. Non infectious corneal ulceration were excluded. Data collected from medical records were demographic features, predisposing factors, history of corneal trauma, associated ocular conditions, visual acuity at the time of presentation and the clinical course. Predisposing risk factors measured were contact lens use, presence of blepharitis, diabetes, lid abnormalities, dry eyes, keratoplasty and refractive surgery. For contact lens wearers any contact lens related risk factors that can lead to keratitis were measured. Pearson's chi-square test was used to carry out statistical analysis wherever required. Results: Contact lens wear, as a risk factor for microbial keratitis, formed 40% of the total study population. Other risk factors identified were dry eyes 24 cases (8%), 10 blepharitis (3%), 22 trauma (8%), abnormal lid position 14 cases (5%). 6 patients keratitis in a graft (2%), 3 had refractive surgery (1%). The most common causative organism isolated was pseudomonas aeroginosa (54%) followed by streptococcus 12%, staph 10%, other organisms 6%. 95% of contact lens wearers had pseudomonas Aeroginosa. This was statistically significant (p< 0.0001). The vast majority, 92% healed with scarring. 1% needed therapeutic keratoplasty and 7% lost to follow up. Risk factors in contact lens wearers were; 41 patients (36%) slept with the contact lenses. 12 (8%) had contact lens related trauma and 8 (7%) had poor hygiene. Sleeping with the contact lenses was statistically significant (p< 0.0001). Conclusion & Recommendation: Contact lens wear is the major risk factor for microbial keratitis in Bahrain. Pseudomonas aeroginosa was the commonest bacteria isolated. Sleeping with the contact lenses is the major risk factor among contact lens wearers. Majority of keratitis patients resulted in permanent scarring on the cornea. Educating the public, especially on contact lens care and precaution, can help reduce this visual morbidity. PMID:20142952

Advantages of using newly developed quartz contact lens with slit illumination from operating microscope.

PubMed

Kiyokawa, Masatoshi; Sakuma, Toshiro; Hatano, Noriko; Mizota, Atsushi; Tanaka, Minoru

2009-06-01

The purpose of this article is to report the characteristics and advantages of using a newly designed quartz contact lens with slit illumination from an operating microscope for intraocular surgery. The new contact lens is made of quartz. The lens is convex-concave and is used in combination with slit illumination from an operating microscope. The optical properties of quartz make this lens less reflective with greater transmittance. The combination of a quartz contact lens with slit illumination provided a brighter and wider field of view than conventional lenses. This system enabled us to perform bimanual vitrectomy and scleral buckling surgery without indirect ophthalmoscope. Small intraocular structures in the posterior pole or in the periphery were detected more easily. In conclusion, the newly designed quartz lens with slit beam illumination from an operating microscope provided a bright, clear and wide surgical field, and allowed intraocular surgery to be performed more easily.

21 CFR 886.5420 - Contact lens inserter/remover.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Contact lens inserter/remover. 886.5420 Section 886.5420 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5420 Contact lens inserter/remover...

Environmental Stability and Infectivity of Hepatitis C Virus (HCV) in Different Human Body Fluids.

PubMed

Pfaender, Stephanie; Helfritz, Fabian A; Siddharta, Anindya; Todt, Daniel; Behrendt, Patrick; Heyden, Julia; Riebesehl, Nina; Willmann, Wiebke; Steinmann, Joerg; Münch, Jan; Ciesek, Sandra; Steinmann, Eike

2018-01-01

Background: Hepatitis C virus (HCV) is a hepatotropic, blood-borne virus, but in up to one-third of infections of the transmission route remained unidentified. Viral genome copies of HCV have been identified in several body fluids, however, non-parental transmission upon exposure to contaminated body fluids seems to be rare. Several body fluids, e.g., tears and saliva, are renowned for their antimicrobial and antiviral properties, nevertheless, HCV stability has never been systematically analyzed in those fluids. Methods: We used state of the art infectious HCV cell culture techniques to investigate the stability of HCV in different body fluids to estimate the potential risk of transmission via patient body fluid material. In addition, we mimicked a potential contamination of HCV in tear fluid and analyzed which impact commercially available contact lens solutions might have in such a scenario. Results: We could demonstrate that HCV remains infectious over several days in body fluids like tears, saliva, semen, and cerebrospinal fluid. Only hydrogen-peroxide contact lens solutions were able to efficiently inactivate HCV in a suspension test. Conclusion: These results indicate that HCV, once it is present in various body fluids of infected patients, remains infective and could potentially contribute to transmission upon direct contact.

Oxygen transport through soft contact lens and cornea: Lens characterization and metabolic modeling

NASA Astrophysics Data System (ADS)

Chhabra, Mahendra

The human cornea requires oxygen to sustain metabolic processes critical for its normal functioning. Any restriction to corneal oxygen supply from the external environment (e.g., by wearing a low oxygen-permeability contact lens) can lead to hypoxia, which may cause corneal edema (swelling), limbal hyperemia, neovascularization, and corneal acidosis. The need for adequate oxygen to the cornea is a major driving force for research and development of hypertransmissible soft contact lenses (SCLs). Currently, there is no standard technique for measuring oxygen permeability (Dk) of hypertransmissible silicone-hydrogel SCLs. In this work, an electrochemistry-based polarographic apparatus was designed, built, and operated to measure oxygen permeability in hypertransmissible SCLs. Unlike conventional methods where a range of lens thickness is needed for determining oxygen permeabilities of SCLs, this apparatus requires only a single lens thickness. The single-lens permeameter provides a reliable, efficient, and economic tool for measuring oxygen permeabilities of commercial hypertransmissible SCLs. The single-lens permeameter measures not only the product Dk, but, following modification, it measures separately diffusivity, D, and solubility, k, of oxygen in hypertransmissible SCLs. These properties are critical for designing better lens materials that ensure sufficient oxygen supply to the cornea. Metabolism of oxygen in the cornea is influenced by contact-lens-induced hypoxia, diseases such as diabetes, surgery, and drug treatment, Thus, estimation of the in-vivo corneal oxygen consumption rate is essential for gauging adequate oxygen supply to the cornea. Therefore, we have developed an unsteady-state reactive-diffusion model for the cornea-contact-lens system to determine in-vivo human corneal oxygen-consumption rate. Finally, a metabolic model was developed to determine the relation between contact-lens oxygen transmissibility (Dk/L) and corneal oxygen deficiency. A new parameter "Oxygen Deficiency Factor" (ODF) is defined to quantify oxygen deficiency in local regions of the cornea. We use this concept to determine the minimum required contact-lens oxygen transmissibility, Dk/L = 150 Barrer/cm, to avoid hypoxia-induced corneal physiologic complications.

Measurement of the refractive index of soft contact lenses during wear.

PubMed

Varikooty, Jalaiah; Keir, Nancy; Woods, Craig A; Fonn, Desmond

2010-01-01

To determine whether the refractive index (RI) of a soft contact lens can be evaluated using refractometry while the lens remains on the eye and to compare this with more traditional ex vivo RI measurements. A slitlamp apparatus was modified to incorporate a customized Atago hand refractometer. With a double-masked study design, nine adapted symptomatic soft contact lens wearers wore a contact lens in each eye (lotrafilcon B and etafilcon A) in a randomized order. In vivo RI was determined from the relative Brix scale measurements immediately after lens insertion and after 1 and 10 hr of lens wear. Ex vivo refractometry was performed after 10 hr of lens wear for comparison. Means +/- standard errors of the means are reported. In vivo RI values at baseline were 1.422 +/- 0.0004 (lotrafilcon B) and 1.405 +/- 0.0021 (etafilcon A); after 1 hr of lens wear, values were 1.423 +/- 0.0006 and 1.408 +/- 0.0007, respectively; and after 10 hr of lens wear, values were 1.424 +/- 0.0004 and 1.411 +/- 0.0010, respectively. Ex vivo RI values at the end of the 10 hr wearing period were 1.424 +/- 0.0003 (lotrafilcon B) and 1.412 +/- 0.0017 (etafilcon A). The change in in vivo RI across the day was statistically significant for the etafilcon A lens (repeated-measures analysis of variance, P<0.01) but not for the lotrafilcon B lens (P>0.05). This novel adaptation of refractometry was able to measure the RI of soft contact lenses during wear (without lens removal). End of day RI measurements using in vivo and ex vivo refractometry were comparable with each other. Future work is required to determine whether this in vivo method can improve our understanding of the relationships between soft contact lens RI, hydration, on-eye lens performance, and symptomology.

A Prototype Antifungal Contact Lens

PubMed Central

Ciolino, Joseph B.; Hudson, Sarah P.; Mobbs, Ashley N.; Hoare, Todd R.; Iwata, Naomi G.; Fink, Gerald R.

2011-01-01

Purpose. To design a contact lens to treat and prevent fungal ocular infections. Methods. Curved contact lenses were created by encapsulating econazole-impregnated poly(lactic-co-glycolic) acid (PLGA) films in poly(hydroxyethyl methacrylate) (pHEMA) by ultraviolet photopolymerization. Release studies were conducted in phosphate-buffered saline at 37°C with continuous shaking. The contact lenses and their release media were tested in an antifungal assay against Candida albicans. Cross sections of the pre- and postrelease contact lenses were characterized by scanning electron microscopy and by Raman spectroscopy. Results. Econazole-eluting contact lenses provided extended antifungal activity against Candida albicans fungi. Fungicidal activity varied in duration and effectiveness depending on the mass of the econazole-PLGA film encapsulated in the contact lens. Conclusions. An econazole-eluting contact lens could be used as a treatment for fungal ocular infections. PMID:21527380

In vitro adhesion of Acanthamoeba castellanii to soft contact lenses depends on water content and disinfection procedure.

PubMed

Reverey, Julia F; Fromme, Roland; Leippe, Matthias; Selhuber-Unkel, Christine

2014-08-01

To compare the potential of different soft contact lenses to be contaminated with Acanthamoeba castellanii as a function of material parameters and cleaning procedures. Different unworn soft hydrogel and silicone hydrogel contact lenses were incubated with human pathogenic A. castellanii. The adhesion of the acanthamoebae was investigated on the contact lenses and put into relation to their material parameters. The efficacy of a recommended contact lens cleaning procedure in reducing A. castellanii adhesion was investigated. We found that material parameters such as elastic modulus, silicone content, ionic properties and swelling do not influence the adhesion of acanthamoebae to soft contact lenses. A material parameter that influenced adhesion significantly was the water content of the lens. With increasing water content, the adhesion of acanthamoebae increased. By following the cleaning instructions of the manufacturer the contamination of the lenses with A. castellanii could be reduced to a minimum, as shown both on contact lenses and in control experiments. With this study we show that for the tested lenses, the adhesion of A. castellanii to contact lenses is independent of the silicone content of the lens, but depends nonlinearly on the water content of the lens. Furthermore, we demonstrate that applying proper lens cleaning procedures minimizes the risk of acanthamoebae adhesion to contact lenses. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Effect of Daily Contact Lens Cleaning on Ocular Adverse Events during Extended Wear.

PubMed

Ozkan, Jerome; Rathi, Varsha M; de la Jara, Percy Lazon; Naduvilath, Thomas; Holden, Brien A; Willcox, Mark D P

2015-02-01

The purpose of the study was to assess what effect daily cleaning of contact lenses with a multipurpose disinfection solution (MPDS), during 30 nights extended wear, would have on contact lens-related adverse events. This was a prospective, open-label, randomized, controlled, parallel-group, 3-month clinical study in which 193 participants were dispensed with lotrafilcon A silicone hydrogel lenses for a 30-day extended-wear schedule and with lenses replaced monthly. Participants were randomized to a control or test group. Test subjects were required to remove lenses daily after waking, clean them with the MPDS, and reinsert the lenses. Control subjects wore lenses without removal for 30 days extended wear. Handling-related lens contamination was assessed at the baseline visit. There was no significant difference between the test and control groups for the incidence of significant corneal infiltrative events (1.3 vs. 4.9%, p = 0.368), total corneal infiltrative events (2.6 vs. 4.9%, p = 0.682), or mechanical events (1.3 vs. 2.5%, p = 1.00). The test group had greater corneal staining (p < 0.047) and fewer mucin balls (p = 0.033). Handling-related lens contamination (unworn lenses) resulted in isolation of Gram-positive bacteria from 92.5% of test lenses compared with 87.5% of control lenses (p = 0.712). Gram-negative bacteria were isolated from 5% of test subjects compared with 2.5% of control subjects (p = 1.00). Fungus was isolated from 2.5% of subjects in both the test and control groups (p = 1.00). The intervention of daily morning cleaning of the lens surface with an MPDS during extended wear did not significantly influence the incidence of adverse events.

Compatibility of phospholipid liposomal spray with silicone hydrogel contact lens wear.

PubMed

Wang, Michael T M; Ganesalingam, Kalaivarny; Loh, Chee Seang; Alberquerque, Trisha; Al-Kanani, Suhaila; Misra, Stuti L; Craig, Jennifer P

2017-02-01

To assess the effects of two weeks of regular phospholipid liposomal spray application on lipid layer grade, tear film stability, subjective comfort, visual acuity, and lipid deposition in silicone hydrogel contact lens wearers. Thirty-one existing contact lens wearers were enrolled and fitted with two week planned replacement silicone hydrogel contact lenses (Acuvue ® Oasys ® ) in a prospective, randomized, paired-eye, investigator-masked trial. A phospholipid liposomal spray (Tears Again ® ) was applied to one eye (randomized) four times daily for two weeks. LogMAR high contrast visual acuity (VA), low contrast glare acuity (LCGA), non-invasive tear film break-up time (NIBUT), and lipid layer grade (LLG) were measured at baseline and day 14, in both treated and control eyes. Subjective comfort relative to baseline, and spectrofluorophotometric assessment of contact lens surface lipid deposition were also assessed on day 14. All measurements did not differ at baseline between treated and control eyes. Lipid layer thickness and tear film stability were increased on day 14 in treated eyes (all p<0.05), but not in control eyes (all p>0.05). A greater proportion of participants reported improved comfort in the treated eye relative to the control eye (p=0.002). There were no significant differences in visual acuity or in contact lens surface lipid deposition, between treated and control eyes, on day 14 (all p>0.05). The phospholipid liposomal spray increased tear film stability, lipid layer thickness and subjective comfort in silicone hydrogel contact lens wearers, without adversely affecting visual acuity or contact lens surface lipid deposition. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Corneal confocal microscopy and dry eye findings in contact lens discomfort patients.

PubMed

Dogan, Aysun Sanal; Gurdal, Canan; Arslan, Nese

2018-02-01

To evaluate the corneal confocal microscopy and dry eye findings in patients with contact lens discomfort. The study included 3 groups of participants: Contact lens wearers using silicone hydrogel soft contact lenses who are symptomatic (CLD, n=15) or asymptomatic (ACL, n=11) and non-wearers as controls (n=14). Duration of contact lens wear, Ocular Surface Disease Index (OSDI) questionnaire responses, fluorescein tear break-uptime (FBUT), and corneal confocal microscopy findings were recorded. Mean age was 25.7±8.2 years and male/female ratio was 7/33. Demographic findings were similar regarding the groups. CLD patients had a longer lens use history than ACL (median 5 vs 2 years, p<0.001). OSDI scores were higher in CLD group than ACL or controls (p<0.001, p=0.002). FBUT was significantly lowest in CLD group, compared to controls and ACL (p<0.001, p=0.039). FBUT was also lower in ACL patients compared to controls (p=0.036). There was no difference between basal epithelium cell counts between all 3 groups. Anterior stromal activated keratocyte numbers were similar between contact lens using groups but was lower in controls (p=0.005). However, dendritiform cells in the sub-basal nerve layer were higher in CLD group compared to controls but similar to ACL (p<0.001, p=0.058). Graded sub-basal nerve tortuosity was more prominent in CLD group than the ACL (p=0.014). Patients with CLD had been wearing contact lenses for longer than those without symptoms. OSDI and FBUT scores were worse in CLD patients. In contact lens discomfort patients, there were increased dendritiform cells, indicating intensified inflammatory status of the cornea. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Effect of a contact lens on mouse retinal in vivo imaging: Effective focal length changes and monochromatic aberrations.

PubMed

Zhang, Pengfei; Mocci, Jacopo; Wahl, Daniel J; Meleppat, Ratheesh Kumar; Manna, Suman K; Quintavalla, Martino; Muradore, Riccardo; Sarunic, Marinko V; Bonora, Stefano; Pugh, Edward N; Zawadzki, Robert J

2018-03-28

For in vivo mouse retinal imaging, especially with Adaptive Optics instruments, application of a contact lens is desirable, as it allows maintenance of cornea hydration and helps to prevent cataract formation during lengthy imaging sessions. However, since the refractive elements of the eye (cornea and lens) serve as the objective for most in vivo retinal imaging systems, the use of a contact lens, even with 0 Dpt. refractive power, can alter the system's optical properties. In this investigation we examined the effective focal length change and the aberrations that arise from use of a contact lens. First, focal length changes were simulated with a Zemax mouse eye model. Then ocular aberrations with and without a 0 Dpt. contact lens were measured with a Shack-Hartmann wavefront sensor (SHWS) in a customized AO-SLO system. Total RMS wavefront errors were measured for two groups of mice (14-month, and 2.5-month-old), decomposed into 66 Zernike aberration terms, and compared. These data revealed that vertical coma and spherical aberrations were increased with use of a contact lens in our system. Based on the ocular wavefront data we evaluated the effect of the contact lens on the imaging system performance as a function of the pupil size. Both RMS error and Strehl ratios were quantified for the two groups of mice, with and without contact lenses, and for different input beam sizes. These results provide information for determining optimum pupil size for retinal imaging without adaptive optics, and raise critical issues for design of mouse optical imaging systems that incorporate contact lenses. Copyright © 2018. Published by Elsevier Ltd.

21 CFR 886.5918 - Rigid gas permeable contact lens care products.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rigid gas permeable contact lens care products. 886.5918 Section 886.5918 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Industry Premarket Notification (510(k)) Guidance Document for Contact Lens Care Products.” [62 FR 30987...

RISK FACTORS FOR CONTACT LENS INDUCED PAPILLARY CONJUNCTIVITIS ASSOCIATED WITH SILICONE HYDROGEL CONTACT LENS WEAR

PubMed Central

Tagliaferri, Angela; Love, Thomas E.; Szczotka-Flynn, Loretta

2014-01-01

BACKGROUND Contact lens induced papillary conjunctivitis (CLPC) continues to be a major cause of dropout during contact lens extended wear. This retrospective study explores risk factors for the development of CLPC during silicone hydrogel lens extended wear. METHODS Data from 205 subjects enrolled in the Longitudinal Analysis of Silicone Hydrogel Contact Lens (LASH) study wearing lotrafilcon A silicone hydrogel lenses for up to 30 days of continuous wear were used to determine risk factors for CLPC in this secondary analysis of the main cohort. The main covariates of interest included substantial lens-associated bacterial bioburden, and topographically determined lens base curve-to-cornea fitting relationships. Additional covariates of interest included history of prior adverse events, time of year, race, education level, gender and other subject demographics. Statistical analyses included univariate logistic regression to assess the impact of potential risk factors on the binary CLPC outcome, and Cox proportional hazards regression to describe the impact of those factors on time-to-CLPC diagnosis. RESULTS Across 12 months of follow-up, 52 subjects (25%) experienced CLPC. No associations were found between CLPC development and the presence of bacterial bioburden, lens-to-cornea fitting relationships, history of prior adverse events, gender or race. CLPC development followed the same seasonal trends as the local peaks in environmental allergans. CONCLUSIONS Lens fit and biodeposits, in the form of lens associated bacterial bioburden, were not associated with the development of CLPC during extended wear with lotrafilcon A silicone hydrogel lenses. PMID:24681609

Ocular response to hydrogen peroxide.

PubMed

Paugh, J R; Brennan, N A; Efron, N

1988-02-01

A controlled, randomized, double-masked study was conducted on eight human subjects to determine the threshold level of hydrogen peroxide, which is toxic when introduced into the eye via a high water content (75%; Durasoft 4) hydrogel contact lens. Subjective comfort, conjunctival hyperemia, corneal and conjunctival epithelial staining, and corneal oxygen uptake were assessed in response to 5-min wear of lenses that were presoaked in isotonic saline solutions of physiologic pH containing 0, 25, 50, 100, 200, 400, and 800 parts per million (ppm) hydrogen peroxide. Higher levels of hydrogen peroxide were associated with greater discomfort (p less than 0.05) and increased conjunctival hyperemia (p less than 0.001). The highest level of hydrogen peroxide tested (800 ppm) did not induce significant corneal or conjunctival epithelial staining or alter the corneal aerobic response. We conclude that residual concentrations of hydrogen peroxide in contact lens care systems should not exceed 100 ppm. Practitioners can use these data to estimate the level of residual hydrogen peroxide to which a patient may have been exposed upon lens application after neutralization.

Cytokine changes in tears and relationship to contact lens discomfort.

PubMed

Willcox, Mark D P; Zhao, Zhenjun; Naduvilath, Thomas; Lazon de la Jara, Percy

2015-01-01

To determine the reproducibility of a multiplex bead assay for measuring cytokines in tears and correlations between ocular discomfort with or without contact lens wear and the concentration of cytokines in tears. Ninety participants (divided into two groups) were enrolled in this prospective study. They were asked to rate their ocular comfort and collect their tears in the morning and just before sleep for 10 days with or without contact lenses. The participants collected their tears using a glass microcapillary tube for both stages. Galyfilcon A lenses were worn on a daily disposable basis during the contact lens stage, and comfort scores and tears were collected before lens insertion and prior to lens removal at the end of the day. Tears were analyzed for cytokine concentrations using a 27-plex multibead assay. Correlations were sought between cytokine concentrations and comfort. There was a significant (p<0.022) decrease in ocular comfort over the day with or without lens wear. The magnitude of ocular discomfort was significantly greater (p<0.009) with lens wear. The concentrations of 12 cytokines differed significantly between the groups; thus, these cytokines were not analyzed further. For the remaining 15 cytokines, interleukin-8 (IL-8) was the only cytokine that changed in both groups during the day without (reduced by >-0.5 Log pg/ml, p<0.001) or with lens wear (reduced by >-0.2 Log pg/ml, p<0.001). The change in the vascular endothelial growth factor (VEGF) concentration only in tears was correlated to ocular comfort, but this was not changed by contact lens wear. Ocular comfort during the day is magnified by contact lens wear. However, the increase in the change in comfort during lens wear was not associated with changes in 15 cytokines in the tear film.

How should initial fit inform soft contact lens prescribing.

PubMed

Boychev, Nikolay; Laughton, Deborah S; Bharwani, Gulshan; Ghuman, Hafsa; Wolffsohn, James S

2016-06-01

To investigate how initial HEMA and silicone-hydrogel (SiHy) contact lens fit on insertion, which informs prescribing decisions, reflect end of day fit. Thirty participants (aged 22.9±4.9 years) were fitted contralaterally with HEMA and SiHy contact lenses. Corneal topography and tear break-up time were assessed pre-lens wear. Centration, lag, post-blink movement during up-gaze and push-up recovery speed were recorded after 5,10,20min and 8h of contact lens wear by a digital slit-lamp biomicroscope camera, along with reported comfort. Lens fit metrics were analysed using bespoke software. Comfort and centration were similar with the HEMA and SiHy lenses (p>0.05), but comfort decreased with time (p<0.01) whereas centration remained stable (F=0.036, p=0.991). Movement-on-blink and lag were greater with the HEMA than the SiHy lens (p<0.01), but movement-on-blink decreased with time after insertion (F=22.423, p<0.001) whereas lag remained stable (F=1.967, p=0.129). Push-up recovery speed was similar with the HEMA and the SiHy lens 5-20min after insertion (p>0.05), but was slower with SiHy after 8h wear (p=0.016). Lens movement on blink and push-up recovery speed was predictive of the movement after 8h of wear after 10-20min SiHy wear, but after 5 to 20min of HEMA lens wear. A HEMA or SiHy contact lens with poor movement on blink/push-up after at least 10min after insertion should be rejected. Copyright © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Morphology of contact lens-induced conjunctival epithelial flaps: a pilot study.

PubMed

Bergmanson, Jan P G; Tukler, Johanna; Leach, Norman E; Alabdelmoneam, Mussaed; Miller, William L

2012-08-01

Conjunctival epithelial flap (CEF) is a conjunctival condition most commonly seen in silicone hydrogel contact lens wearers. This study utilized impression cytology to investigate the cellular composition and health of CEFs. Nine (9) subjects were enrolled - 3 non-lens wearers, 3 contact lens wearers without CEF, and 3 contact lens wearers with CEFs wearing 8.4/13.8 lotrafilcon A lenses. Impression cytology samples were collected from the flap or similar locations, if CEF was absent, using rectangular 5 mm × 2 mm Millipore HAWP02500 membrane filters. The filters were gently pressed onto the conjunctiva, subsequently fixed in 95% alcohol, stained with hematoxylin-eosin and evaluated under an Olympus IX70 microscope. Measurements of the longest cell and nucleus dimensions were measured on 40 cells from each filter by utilizing NIH Image 1.63. CEF consisted of multilayers of epithelial and goblet cells and were devoid of inflammatory cells, basement membrane material and stromal tissue. The cytoplasmic and nuclear dimensions were similar within the groups and the cytoplasm-to-nucleus ratio was not different between the flap group and the non-lens wearing group. The CEF appeared to be formed by healthy epithelial and goblet cells that have been dislocated from their normal location along the conjunctival surface by the lens edge. No inflammatory cells were present in this contact lens induced condition, which is reported to be associated most commonly with the silicone hydrogel material. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Biological and Clinical Implications of Lysozyme Deposition on Soft Contact Lenses

PubMed Central

Omali, Negar Babaei; Subbaraman, Lakshman N.; Coles-Brennan, Chantal; Fadli, Zohra; Jones, Lyndon W.

2015-01-01

ABSTRACT Within a few minutes of wear, contact lenses become rapidly coated with a variety of tear film components, including proteins, lipids, and mucins. Tears have a rich and complex composition, allowing a wide range of interactions and competitive processes, with the first event observed at the interface between a contact lens and tear fluid being protein adsorption. Protein adsorption on hydrogel contact lenses is a complex process involving a variety of factors relating to both the protein in question and the lens material. Among tear proteins, lysozyme is a major protein that has both antibacterial and anti-inflammatory functions. Contact lens materials that have high ionicity and high water content have an increased affinity to accumulate lysozyme during wear, when compared with other soft lens materials, notably silicone hydrogel lenses. This review provides an overview of tear film proteins, with a specific focus on lysozyme, and examines various factors that influence protein deposition on contact lenses. In addition, the impact of lysozyme deposition on various ocular physiological responses and bacterial adhesion to lenses and the interaction of lysozyme with other tear proteins are reviewed. This comprehensive review suggests that deposition of lysozyme on contact lens materials may provide a number of beneficial effects during contact lens wear. PMID:26002002

Omni-focal refractive focus correction technology as a substitute for bi/multi-focal intraocular lenses, contact lenses, and spectacles

NASA Astrophysics Data System (ADS)

Ben Yaish, Shai; Zlotnik, Alex; Raveh, Ido; Yehezkel, Oren; Belkin, Michael; Lahav, Karen; Zalevsky, Zeev

2009-02-01

We present novel technology for extension in depth of focus of imaging lenses for use in ophthalmic lenses correcting myopia, hyperopia with regular/irregular astigmatism and presbyopia. This technology produces continuous focus without appreciable loss of energy. It is incorporated as a coating or engraving on the surface for spectacles, contact or intraocular lenses. It was fabricated and tested in simulations and in clinical trials. From the various testing this technology seems to provide a satisfactory single-lens solution. Obtained performance is apparently better than those of existing multi/bifocal lenses and it is modular enough to provide solution to various ophthalmic applications.

Randomized trial of the effect of contact lens wear on self-perception in children.

PubMed

Walline, Jeffrey J; Jones, Lisa A; Sinnott, Loraine; Chitkara, Monica; Coffey, Bradley; Jackson, John Mark; Manny, Ruth E; Rah, Marjorie J; Prinstein, Mitchell J

2009-03-01

To determine whether contact lens wear affects children's self-perceptions. The Adolescent and Child Health Initiative to Encourage Vision Empowerment Study was a randomized, single-masked trial conducted at five clinical centers in the United States. Subjects were 8- to 11-year-old myopic children randomly assigned to wear spectacles (n = 237) or soft contact lenses (n = 247) for 3 years. The primary endpoint was the Self-Perception Profile for Children Global Self-Worth scale. Secondary outcomes included the Physical Appearance, Athletic Competence, Scholastic Competence, Behavioral Conduct, and Social Acceptance Self-Perception Profile for Children scales. Global self-worth was not affected by contact lens wear [analysis of variance (ANOVA), difference = 0.06; 95% CI, -0.004 to 0.117]. Physical appearance (ANOVA, difference = 0.15; 95% CI, 0.07 to 0.22), athletic competence (ANOVA, difference = 0.08; 95% CI, 0.01 to 0.15), and social acceptance (ANOVA, difference = 0.10; 95% CI, 0.03 to 0.17) were all greater for contact lens wearers. Although contact lens wear does not affect global self-perceptions of 8- to 11-year-old myopic children their physical appearance, athletic competence, and social acceptance self-perceptions are likely to improve with contact lens wear. Eye care practitioners should consider the social and visual benefits of contact lens wear when choosing the most appropriate vision correction modality for children as young as 8 years of age.

Composition of incubation solution impacts in vitro protein uptake to silicone hydrogel contact lenses

PubMed Central

Heynen, Miriam; Luensmann, Doerte; Jones, Lyndon

2012-01-01

Purpose To determine the impact of incubation solution composition on protein deposition to silicone hydrogel (SH) contact lenses using a simplistic and a complex model of the tear film. Methods Three SH materials – senofilcon A (SA), lotrafilcon B (LB), and balafilcon A (BA) – were incubated in two different solutions; Solution A was a simplistic augmented buffered saline solution containing a single protein, whereas Solution B was a complex artificial tear solution (ATS), containing the augmented buffered saline solution in addition to proteins, lipids, and mucins (pH=7.4). The proteins of interest (lysozyme, lactoferrin, albumin) were radiolabeled with Iodine-125 (2% protein of interest) and the accumulation of the conjugated protein to the lens materials was determined after 1, 7, 14, and 28 days of incubation. Protein deposition was measured using a gamma counter and the raw data were translated into absolute amounts (µg/lens) via extrapolation from standards. Results After 28 days, lysozyme uptake was significantly lower on BA lenses when incubated in Solution A (33.7 μg) compared to Solution B (56.2 μg), p<0.001. SA lenses deposited similar amounts of lysozyme when incubated in either Solution A (2.6 μg) or Solution B (4.1 μg), p>0.05. LB lenses also deposited similar amounts of lysozyme for both solutions (Solution A: 5.0 μg, Solution B: 4.7 μg, p>0.05). After 28 days, BA lenses accumulated approximately twice the amount of lactoferrin than the other lens materials, with 30.3 μg depositing when exposed to Solution A and 22.0 μg with Solution B. The difference between the two solutions was statistically significant (p<0.001). LB materials deposited significantly greater amounts of lactoferrin when incubated in Solution A (16.6 μg) compared to Solution B (10.3 μg), p<0.001. Similar amounts of lactoferrin were accumulated onto SA lenses regardless of incubation solution composition (Solution A: 8.2 μg, Solution B: 11.2 μg, p>0.05). After 28 days, albumin deposition onto BA lenses was significantly greater when lenses were incubated in Solution B (1.7 μg) compared to Solution A (0.9 μg), p<0.001. Similar amounts of albumin were deposited on SA lenses when incubated in either solution (0.6 μg versus 0.7 μg, p>0.05). LB lenses incubated in Solution A deposited more albumin compared to Solution B (0.9 μg versus 0.6 μg), p=0.003. Discussion Protein deposition onto SH materials varied when contact lenses were incubated in either a complex ATS compared to a single protein solution. More lysozyme accumulated onto BA lenses incubated in a complex analog of the human tear film, whereas lactoferrin deposited onto SA lenses independent of incubation solution composition. To better mimic the ex vivo environment, future studies should use more appropriate analogs of the tear film. PMID:22355245

Evaluations of Shorter Exposures of Contact Lens Cleaning Solutions against Fusarium oxysporum Species Complex and Fusarium solani Species Complex To Simulate Inappropriate Usage▿

PubMed Central

Ramani, Rama; Chaturvedi, Vishnu

2011-01-01

An outbreak of Fusarium keratitis in contact lens users resulted in withdrawal of ReNu with MoistureLoc solution, although the exact cause of the outbreak remains enigmatic. We evaluated current and discontinued multipurpose cleaning solutions (MPSs; MoistureLoc, Equate, MultiPlus, and OptiFree Express) against plankton- and biofilm-derived cells of Fusarium oxysporum species complex (FOSC) and F. solani species complex (FSSC). The methods included a traditional assay based on CFU counts and a novel flow cytometry (FC) assay based on percent cell subpopulation (PCS) stained with two fluorochromes (Sytox Red and 5-chloromethylfluorescein diacetate). The tests were done with the respective manufacturers' recommended cleaning regimens (240 to 360 min) and under shorter exposures (15 to 60 min) to simulate inappropriate usage by the customers. FC assay measured PCS, which was available rapidly, in 5 to 7 h, whereas 24 to 48 h was needed for CFU counts, and there was good correlation between the two methods (r2 = 0.97). FC assays allowed identification of injured fungal cells, which are likely to be missed with growth assays. In general, a time- and inoculum-dependent survival pattern was seen for both FOSC and FSSC cells, and biofilm-derived cells were more resistant than plankton-derived cells. MultiPlus and Equate produced 100% sterilization of fungi even under shorter exposures. However, biofilm FOSC and FSSC cells survived for up to 4 h in MoistureLoc solution and up to 6 h in OptiFree Express solution under shorter exposure times. This finding was enigmatic, as OptiFree Express is not associated with any outbreak of Fusarium keratitis. This study provides additional support for possible roles that improper lens cleaning regimens and fungal biofilms could play as predisposing factors for Fusarium keratitis. PMID:21300826

Corneal epithelial cell biocompatibility to silicone hydrogel and conventional hydrogel contact lens packaging solutions

PubMed Central

Tanti, N.C.; Jones, L.; Sheardown, H.

2010-01-01

Purpose Although all contact lenses (CLs) are applied initially to the eye directly from a packaging solution, little is known about the effects of these solutions on human corneal epithelial cells (HCECs). Due to the porous nature of CL materials, they have the potential to sorb components of the packaging solution during storage, which could then be subsequently released upon insertion of the CL on the eye. The purpose of this study was to investigate the effect of various packaging solutions on HCECs, using an in vitro model. Methods An in vitro assay was developed whereby various silicone hydrogels and conventional, poly-2-hydroxyethylmethacrylate  (polyHEMA)-based lens materials were removed directly from their packaging and then incubated for up to 24 h with HCECs. The effect of the retained and released packaging solution components on HCECs was assessed by measuring cell viability, adhesion phenotype, and apoptosis. Results Incubation of HCECs with CLs stored in borate-buffered packaging solutions resulted in a significant reduction in cell viability. Adherent cells incubated with these CLs also exhibited reduced levels of β1 and α3 integrin. Soaking borate-buffered packaged CLs in PBS before cell incubation resolved viability and integrin expression in all cases, with the exception of galyfilcon A and balafilcon A, from which a 20% reduction in cell viability was still observed. In comparison, CLs stored in phosphate-buffered packaging solutions had cellular viability and expression of integrins similar to control cells (cells incubated in the absence of a lens). When incubated with cells at a 10% concentration in serum-free medium, borate-buffered packaging solutions and borate-containing saline (Unisol 4) significantly reduced cell viability and integrin expression. Neither caspase activation nor annexin V binding was observed on cells following exposure to borate buffer solution. However, a significant decrease in reactive oxygen species was observed at 24 h. These latter results suggest that in vitro exposure to low concentration of borate/boric acid results in cell dysfunction, leading to necrosis rather than apoptosis. Conclusions Borate-buffered packaging solutions were shown to adversely affect the viability and integrin expression of HCECs in vitro. When used in ophthalmic packaging solutions, the antimicrobial properties of borate buffer may be outweighed by its relatively cytotoxic effects on cells. PMID:20169012

Corneal epithelial cell biocompatibility to silicone hydrogel and conventional hydrogel contact lens packaging solutions.

PubMed

Gorbet, M B; Tanti, N C; Jones, L; Sheardown, H

2010-02-19

Although all contact lenses (CLs) are applied initially to the eye directly from a packaging solution, little is known about the effects of these solutions on human corneal epithelial cells (HCECs). Due to the porous nature of CL materials, they have the potential to sorb components of the packaging solution during storage, which could then be subsequently released upon insertion of the CL on the eye. The purpose of this study was to investigate the effect of various packaging solutions on HCECs, using an in vitro model. An in vitro assay was developed whereby various silicone hydrogels and conventional, poly-2-hydroxyethylmethacrylate (polyHEMA)-based lens materials were removed directly from their packaging and then incubated for up to 24 h with HCECs. The effect of the retained and released packaging solution components on HCECs was assessed by measuring cell viability, adhesion phenotype, and apoptosis. Incubation of HCECs with CLs stored in borate-buffered packaging solutions resulted in a significant reduction in cell viability. Adherent cells incubated with these CLs also exhibited reduced levels of beta(1) and alpha(3) integrin. Soaking borate-buffered packaged CLs in PBS before cell incubation resolved viability and integrin expression in all cases, with the exception of galyfilcon A and balafilcon A, from which a 20% reduction in cell viability was still observed. In comparison, CLs stored in phosphate-buffered packaging solutions had cellular viability and expression of integrins similar to control cells (cells incubated in the absence of a lens). When incubated with cells at a 10% concentration in serum-free medium, borate-buffered packaging solutions and borate-containing saline (Unisol 4) significantly reduced cell viability and integrin expression. Neither caspase activation nor annexin V binding was observed on cells following exposure to borate buffer solution. However, a significant decrease in reactive oxygen species was observed at 24 h. These latter results suggest that in vitro exposure to low concentration of borate/boric acid results in cell dysfunction, leading to necrosis rather than apoptosis. Borate-buffered packaging solutions were shown to adversely affect the viability and integrin expression of HCECs in vitro. When used in ophthalmic packaging solutions, the antimicrobial properties of borate buffer may be outweighed by its relatively cytotoxic effects on cells.

Simultaneously Load and Extended Release of Betamethasone and Ciprofloxacin from Vitamin E-Loaded Silicone-Based Soft Contact Lenses.

PubMed

Rad, Maryam Shayani; Mohajeri, Seyed Ahmad

2016-09-01

The purpose of the present study was to evaluate the efficacy of commercial soft contact lenses, loaded with vitamin E, as ocular drug delivery systems for simultaneous loading and release of ciprofloxacin (Cipro) and betamethasone (BMZ) in artificial tears. In this study, we applied vitamin E as a barrier to increase BMZ-Cipro loading into three commercial silicone-based soft contact lenses and control their simultaneous release into the artificial lachrymal fluid. Two different concentrations of vitamin E solution (0.1 and 0.2 g/ml) were used, and various parameters including changes in lens diameter, water content, ultraviolet-visible light (UV-Vis) transmittance, drug-binding properties, and drug release profile were investigated. The obtained results indicated that vitamin E significantly reduced the swelling properties of contact lenses in aqueous media, while it enhanced the lens diameter in both dry and hydrated states. Vitamin E had no significant effects on visible transmittance, while it blocked UV radiation, which could be harmful for the eye surface. Our findings revealed that vitamin E improved the simultaneous loading amount of BMZ-Cipro into soft contact lenses. Additionally, BMZ and Cipro release rates significantly reduced after using vitamin E as a hydrophobic diffusion barrier. After soaking the lenses in 0.1 and 0.2 g/ml of vitamin E solution, BMZ release time increased by 28.8-81.6 and 182.4-201 folds, respectively. Moreover, Cipro release time increased by 12-18 and 1152-2313 folds, respectively. The results of the present study indicated the efficacy of vitamin E as a diffusion barrier in developing a controlled drug delivery system for the simultaneous loading of BMZ and Cipro and sustaining their release from soft contact lenses.

Practitioner Perceptions of Patients Wearing Decorative Contact Lenses Purchased Through Unauthorized Sellers.

PubMed

Gaiser, Hilary; Ho, Connie; Janier, Nicole; Wee, Amy; Johnson, Catherine; Watanabe, Ronald

2017-03-01

To describe practitioner experiences regarding ocular complications in patients wearing decorative contact lenses, and to investigate the compliance of unauthorized distributors of decorative contact lenses to current Food and Drug Administration (FDA) and Federal Trade Commission (FTC) regulations. Also, to provide data to support a more targeted public health approach to reducing the incidence of illegal contact lens sales and associated ocular complications. An institutional review board-approved online survey was distributed through mass email to a list of 98 optometrists in the Boston, MA area. Concurrently, an empirical evaluation of independent, online decorative contact lens sellers who were not associated with FDA-approved contact lens manufacturers was performed to determine their adherence to FDA and FTC guidelines. The first 18 noncoincidental websites that resulted from a Google search for "costume contact lens sellers" and "cosmetic contact lens sellers" were examined as to the brands and parameters of lenses being sold, whether or not a valid prescription was required or verified, and if consumer education was provided. Twenty-two optometrists completed the online survey. Seventy-seven percent of respondents reported having patients with complications from decorative contact lenses that were purchased both legally and illegally. The most common age group for complications was 18 to 25 years (61%). One third of complications were seen in first-time lens wearers, half of whom never received proper care instructions or were unaware that care instructions existed. One quarter of the lenses were purchased illegally with unlicensed stores being the most common place of purchase. Of the 18 online sites examined, 72% of sellers failed to adhere to FTC and FDA regulations. A significant number of individuals who obtain contact lenses illegally from unauthorized sources are young adults. Most unauthorized sellers reviewed did not adhere to the proper protocol for selling contact lenses or instruct their customers on proper lens wear and care. A significant percentage of optometrists responding to the survey reported complications associated with contact lenses purchased through unauthorized sources, suggesting that the risk of contact lens-related complications increases when the lenses are purchased from one of these sources.

Validating a new device for measuring tear evaporation rates.

PubMed

Rohit, Athira; Ehrmann, Klaus; Naduvilath, Thomas; Willcox, Mark; Stapleton, Fiona

2014-01-01

To calibrate and validate a commercially available dermatology instrument to measure tear evaporation rate of contact lens wearers. A dermatology instrument was modified by attaching a swim goggle cup such that the cup sealed around the eye socket. Results for the unmodified instrument are dependent on probe area and enclosed volume. Calibration curves were established using a model eye, to account for individual variations in chamber volume and exposed area. Fifteen participants were recruited and the study included a contact lens wear and a no contact lens wear stage. Day and diurnal variation of the measurements were assessed by taking the measurement three times a day over 2 days. The coefficient of repeatability of the measurement was calculated and a linear mixed model assessed the influence of humidity, temperature, contact lens wear, day and diurnal variations on tear evaporation rate. The associations between variables were assessed using Pearson correlation coefficient. Absolute evaporation rates with and without contact lens wear were calculated based on the new calibration. The measurements were most repeatable during the evening with no lens wear (COR = 49 g m⁻² h) and least repeatable during the evening with contact lens wear (COR = 93 g m⁻² h). Humidity (p = 0.007), and contact lens wear (p < 0.01), significantly affected the tear evaporation rate. However, temperature (p = 0.54) diurnal variation (p = 0.85) and different days (p = 0.65) had no significant effect after controlling for humidity. Tear evaporation rates can be measured using a modified dermatology instrument. Measurements were higher and more variable with lens wear consistent with previous literature. Control of environmental conditions is important as a higher humidity results in a reduced evaporation rate. © 2013 The Authors Ophthalmic & Physiological Optics © 2013 The College of Optometrists.

[Keratoconus special soft contact lens fitting].

PubMed

Yamazaki, Ester Sakae; da Silva, Vanessa Cristina Batista; Morimitsu, Vagner; Sobrinho, Marcelo; Fukushima, Nelson; Lipener, César

2006-01-01

To evaluate the fitting and use of a soft contact lens in keratoconic patients. Retrospective study on 80 eyes of 66 patients, fitted with a special soft contact lens for keratoconus, at the Contact Lens Section of UNIFESP and private clinics. Keratoconus was classified according to degrees of disease severity by keratometric pattern. Age, gender, diagnosis, keratometry, visual acuity, spherical equivalent (SE), base curve and clinical indication were recorded. Of 66 patients (80 eyes) with keratoconus the mean age was 29 years, 51.5% were men and 48.5% women. According to the groups: 15.0% were incipient, 53.7% moderate, 26.3% advanced and 5.0% were severe. The majority of the eyes of patients using contact lenses (91.25%) achieved visual acuity better than 20/40. To 88 eyes 58% were tihed with lens with spherical power (mean -5.45 diopters) and 41% with spherocylinder power (from -0.5 to -5.00 cylindrical diopters). The most frequent base curve was 7.6 in 61% of the eyes. The main reasons for this special lens fitting were due to reduced tolerance and poor fitting pattern achieved with other lenses. The special soft contact lens is useful in fitting difficult keratoconic patients by offering comfort and improving visual rehabilitation that may allow more patients to postpone the need for corneal transplant.

Research on the relation between the contact angle and the interface curvature radius of electrowetting liquid zoom lens

NASA Astrophysics Data System (ADS)

Zhao, Cunhua; Liang, Huiqin; Cui, Dongqing; Hong, Xinhua; Wei, Daling; Gao, Changliu

2011-08-01

In the ultralight or ultrathin applied domain of zoom lens, the traditional glass / plastic lens is limited for manufacture technology or cost. Therefore, a liquid lens was put forward to solve the problems. The liquid zoom lens has the merits of lower cost, smaller volume, quicker response, lower energy consumption, continuous zoom and higher accuracy. In liquid zoom lens the precise focal length is obtained by the contact angle changing to affect the curvature radius of interface. In our works, the relations of the exerted voltage, the contact angle, the curvature radius and the focal length were researched and accurately calculated. The calculation of the focal length provides an important theoretical basis for instructing the design of liquid zoom lens.

Optical Assessment of Soft Contact Lens Edge-Thickness.

PubMed

Tankam, Patrice; Won, Jungeun; Canavesi, Cristina; Cox, Ian; Rolland, Jannick P

2016-08-01

To assess the edge shape of soft contact lenses using Gabor-Domain Optical Coherence Microscopy (GD-OCM) with a 2-μm imaging resolution in three dimensions and to generate edge-thickness profiles at different distances from the edge tip of soft contact lenses. A high-speed custom-designed GD-OCM system was used to produce 3D images of the edge of an experimental soft contact lens (Bausch + Lomb, Rochester, NY) in four different configurations: in air, submerged into water, submerged into saline with contrast agent, and placed onto the cornea of a porcine eyeball. An algorithm to compute the edge-thickness was developed and applied to cross-sectional images. The proposed algorithm includes the accurate detection of the interfaces between the lens and the environment, and the correction of the refraction error. The sharply defined edge tip of a soft contact lens was visualized in 3D. Results showed precise thickness measurement of the contact lens edge profile. Fifty cross-sectional image frames for each configuration were used to test the robustness of the algorithm in evaluating the edge-thickness at any distance from the edge tip. The precision of the measurements was less than 0.2 μm. The results confirmed the ability of GD-OCM to provide high-definition images of soft contact lens edges. As a nondestructive, precise, and fast metrology tool for soft contact lens measurement, the integration of GD-OCM in the design and manufacturing of contact lenses will be beneficial for further improvement in edge design and quality control. In the clinical perspective, the in vivo evaluation of the lens fitted onto the cornea will advance our understanding of how the edge interacts with the ocular surface. The latter will provide insights into the impact of long-term use of contact lenses on the visual performance.

Optical Assessment of Soft Contact Lens Edge-Thickness

PubMed Central

Tankam, Patrice; Won, Jungeun; Canavesi, Cristina; Cox, Ian; Rolland, Jannick P.

2016-01-01

Purpose To assess the edge shape of soft contact lenses using Gabor-Domain Optical Coherence Microscopy (GD-OCM) with a 2 μm imaging resolution in three dimensions, and to generate edge-thickness profiles at different distances from the edge tip of soft contact lenses. Methods A high-speed custom-designed GD-OCM system was used to produce 3D images of the edge of an experimental soft contact lens (Bausch + Lomb, Rochester NY) in four different configurations: in air, submerged into water, submerged into saline with contrast agent, and placed onto the cornea of a porcine eyeball. An algorithm to compute the edge-thickness was developed and applied to cross-sectional images. The proposed algorithm includes the accurate detection of the interfaces between the lens and the environment, and the correction of the refraction error. Results The sharply defined edge tip of a soft contact lens was visualized in 3D. Results showed precise thickness measurement of the contact lens edge profile. 50 cross-sectional image frames for each configuration were used to test the robustness of the algorithm in evaluating the edge-thickness at any distance from the edge tip. The precision of the measurements was less than 0.2 μm. Conclusions The results confirmed the ability of GD-OCM to provide high definition images of soft contact lens edges. As a non-destructive, precise, and fast metrology tool for soft contact lens measurement, the integration of GD-OCM in the design and manufacturing of contact lenses will be beneficial for further improvement in edge design and quality control. In the clinical perspective, the in-vivo evaluation of the lens fitted onto the cornea will advance our understanding of how the edge interacts with the ocular surface. The latter will provide insights into the impact of long-term use of contact lenses on the visual performance. PMID:27232902

Daily disposable contact lens prescribing around the world.

PubMed

Efron, Nathan; Morgan, Philip B; Helland, Magne; Itoi, Motozumi; Jones, Deborah; Nichols, Jason J; van der Worp, Eef; Woods, Craig A

2010-10-01

Daily disposable contact lenses were introduced into the market 16 years ago. Data that we have gathered from annual contact lens fitting surveys conducted in Australia, Canada, Japan, The Netherlands, Norway, the UK and the USA between 2000 and 2008 indicates an overall increase in daily disposable lens fitting during this period. Daily disposable lenses are especially popular in Japan, Norway and the UK. There is a trend for these lenses to be fitted on a part-time basis. Males are over-represented in daily disposable lens fitting-a trend that is especially evident in Canada. Daily disposable lens wearers are about two years younger than wearers of reusable lenses in Japan and The Netherlands. The convenience and health benefits of daily disposable lenses are expected to fuel continued growth in this sector. Copyright (c) 2010 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Bulbar conjunctival fluorescein staining in hydrogel contact lens wearers.

PubMed

Lakkis, C; Brennan, N A

1996-07-01

To evaluate the clinical usefulness of bulbar conjunctival staining in assessing hydrogel contact lens patients. Overall staining, as well as staining at five separate sites (limbal, nasal band, temporal band, superior, and inferior) was graded on an analog scale in 48 contact lens wearing subjects and 50 controls. The degree to which subjects experienced sensations of dryness, wateriness, itchiness, grittiness, and comfort was also assessed using analog scales. Some measure of conjunctival staining was noted in 98% of subjects, with contact lens wearers showing statistically significant greater staining than controls. Only 12% of controls showed staining of greater than grade 1 (equivalent), whereas 62% of contact lens wearers were above this level. Regression analysis showed that overall staining was a function of whether contact lenses were worn, the degree of dryness, and the amount of itchiness. Conjunctival fluorescein staining appears to serve some clinical usefulness as a composite indicator for certain factors and symptoms and, in addition, provides information which is unique for each individual.

The efficiency of contact lens care regimens on protein removal from hydrogel and silicone hydrogel lenses

PubMed Central

Heynen, Miriam; Liu, Lina; Sheardown, Heather; Jones, Lyndon

2010-01-01

Purpose To investigate the efficiency of lysozyme and albumin removal from silicone hydrogel and conventional contact lenses, using a polyhexamethylene biguanide multipurpose solution (MPS) in a soaking or rubbing/soaking application and a hydrogen peroxide system (H2O2). Methods Etafilcon A, lotrafilcon B and balafilcon A materials were incubated in protein solutions for up to 14 days. Lenses were either placed in radiolabeled protein to quantify the amount deposited or in fluorescent-conjugated protein to identify its location, using confocal laser scanning microscopy (CLSM). Lenses were either rinsed with PBS or soaked overnight in H2O2 or MPS with and without lens rubbing. Results After 14 days lysozyme was highest on etafilcon A (2,200 μg) >balafilcon A (50 µg) >lotrafilcon B (9.7 µg) and albumin was highest on balafilcon A (1.9 µg) =lotrafilcon B (1.8 µg) >etafilcon A (0.2 µg). Lysozyme removal was greatest for balafilcon A >etafilcon A >lotrafilcon B, with etafilcon A showing the most change in protein distribution. Albumin removal was highest from etafilcon A >balafilcon A >lotrafilcon B. H2O2 exhibited greater lysozyme removal from etafilcon A compared to both MPS procedures (p<0.001) but performed similarly for lotrafilcon B and balafilcon A lenses (p>0.62). Albumin removal was solely material specific, while all care regimens performed to a similar degree (p>0.69). Conclusions Protein removal efficiency for the regimens evaluated depended on the lens material and protein type. Overall, lens rubbing with MPS before soaking did not reduce the protein content on the lenses compared to nonrubbed lenses (p=0.89). PMID:20098668

The influence of end of day silicone hydrogel daily disposable contact lens fit on ocular comfort, physiology and lens wettability.

PubMed

Wolffsohn, James; Hall, Lee; Mroczkowska, Stephanie; Hunt, Olivia A; Bilkhu, Paramdeep; Drew, Tom; Sheppard, Amy

2015-10-01

To quantify the end-of-day silicone-hydrogel daily disposable contact lens fit and its influence of on ocular comfort, physiology and lens wettability. Thirty-nine subjects (22.1±3.5 years) were randomised to wear each of 3 silicone-hydrogel daily-disposable contact lenses (narafilcon A, delefilcon A and filcon II 3), bilaterally, for one week. Lens fit was assessed objectively using a digital video slit-lamp at 8, 12 and 16h after lens insertion. Hyperaemia, non-invasive tear break-up time, tear meniscus height and comfort were also evaluated at these timepoints, while corneal and conjunctival staining were assessed on lens removal. Lens fit assessments were not different between brands (P>0.05), with the exception of the movement at blink where narafilcon A was more mobile. Overall, lag reduced but push-up speed increased from 8 to 12h (P<0.05), but remained stable from 12 to 16h (P>0.05). Movement-on-blink was unaffected by wear-time (F=0.403, P=0.670). A more mobile lens fit with one brand did not indicate that person would have a more mobile fit with another brand (r=-0.06 to 0.63). Lens fit was not correlated with comfort, ocular physiology or lens wettability (P>0.01). Among the lenses tested, objective lens fit changed between 8h and 12h of lens wear. The weak correlation in individual lens fit between brands indicates that fit is dependent on more than ocular shape. Consequently, substitution of a different lens brand with similar parameters will not necessarily provide comparable lens fit. Copyright © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Altered bulbar conjunctival microcirculation in response to contact lens wear

PubMed Central

Chen, Wan; Xu, Zhe; Jiang, Hong; Zhou, Jin; Wang, Liang; Wang, Jianhua

2015-01-01

Purpose This study was conducted to determine blood flow velocities and corresponding vessel diameters to characterize the response of the bulbar conjunctival microvasculature to contact lens wear. Methods A Functional Slit-lamp Biomicroscope (FSLB), an adapted traditional slit-lamp, was used to image the temporal bulbar conjunctiva of 22 healthy subjects before and after 6 hours of contact lens wear. All of the measurable venules on the conjunctiva were processed to yield vessel diameters and blood flow velocities. Results The averaged blood flow velocity increased from 0.51 ± 0.20 mm/s to 0.65 ± 0.22 mm/s (P < 0.001) after 6 hours of lens wear. The blood flow velocity distribution showed a velocity increase that correlated with the vessel diameter increase from the baseline (r = 0.826, P < 0.05). This pattern maintained a similar trend after 6 hours of lens wear (r = 0.925, P < 0.05), and increased velocities were found across all of the vessel diameter ranges (P < 0.001). Conclusions Blood flow velocity increases across all of the vessel diameter ranges in response to contact lens wear. FSLB is capable of characterizing the bulbar microvascular response to contact lens wear. PMID:27078615

Adhesion of Stenotrophomonas maltophilia, Delftia acidovorans, and Achromobacter xylosoxidans to Contact Lenses.

PubMed

Vijay, Ajay Kumar; Willcox, Mark D P

2017-09-26

Contact lens cases become contaminated with microbes during use. We wished to compare the adhesion of uncommon bacterial contaminants isolated from lens cases to contact lenses with and without organic soil. Strains of Delftia acidovorans (001), Stenotrophomonas maltophilia (002 and 006), and Achromobacter xylosoxidans (001) isolated from contact lens cases (test strains) and Pseudomonas aeruginosa (Paer1) isolated from eyes at the time of infiltrative response (control strain) were used. Bacteria were grown and resuspended in phosphate-buffered saline (PBS) or 10% organic soil (heat-killed Saccharomyces cerevisiae resuspended in complement inactivated bovine serum). Two silicone hydrogel (senofilcon A and comfilcon A) and one hydrogel lens (etafilcon A) lens materials were used. Bacteria (1.0×10 and 1.0×10 colony-forming units/mL; CFU/mL) adhered to lenses for 24 hr and the numbers of bacteria adherent to each lens type (with and without organic soil) were estimated by culture. All the four test strains adhered in significantly greater numbers to contact lenses after incubation in inoculum prepared with organic soil compared with PBS-D. acidovorans 001 (0.7 log10 CFU; P<0.05), S. maltophilia 002 (1.7 log10 CFU; P<0.05), S. maltophilia 006 (0.9 log10 CFU; P<0.05), and A. xylosoxidans 001 (0.4 log10 CFU; P<0.05). However, the presence of organic soil did not increase adhesion of P. aeruginosa Paer1 (-0.1 log10 CFU; P>0.05). Achromobacter xylosoxidans 001 (P<0.01), D. acidovorans 001 (P<0.01), and S. maltophilia 002 (P<0.01) significantly differed in their adhesion to the three contact lens materials. Bacteria that are commonly found in contact lens cases adhered to contact lenses in relatively high numbers in the presence of organic soil. This might indicate that a similar phenomenon occurs in the presence of tears. This may facilitate their transfer from the lens to the cornea and the production of corneal infiltrates.

Wearable smart sensor systems integrated on soft contact lenses for wireless ocular diagnostics

PubMed Central

Kim, Joohee; Kim, Minji; Lee, Mi-Sun; Kim, Kukjoo; Ji, Sangyoon; Kim, Yun-Tae; Park, Jihun; Na, Kyungmin; Bae, Kwi-Hyun; Kyun Kim, Hong; Bien, Franklin; Young Lee, Chang; Park, Jang-Ung

2017-01-01

Wearable contact lenses which can monitor physiological parameters have attracted substantial interests due to the capability of direct detection of biomarkers contained in body fluids. However, previously reported contact lens sensors can only monitor a single analyte at a time. Furthermore, such ocular contact lenses generally obstruct the field of vision of the subject. Here, we developed a multifunctional contact lens sensor that alleviates some of these limitations since it was developed on an actual ocular contact lens. It was also designed to monitor glucose within tears, as well as intraocular pressure using the resistance and capacitance of the electronic device. Furthermore, in-vivo and in-vitro tests using a live rabbit and bovine eyeball demonstrated its reliable operation. Our developed contact lens sensor can measure the glucose level in tear fluid and intraocular pressure simultaneously but yet independently based on different electrical responses. PMID:28447604

Wearable smart sensor systems integrated on soft contact lenses for wireless ocular diagnostics.

PubMed

Kim, Joohee; Kim, Minji; Lee, Mi-Sun; Kim, Kukjoo; Ji, Sangyoon; Kim, Yun-Tae; Park, Jihun; Na, Kyungmin; Bae, Kwi-Hyun; Kyun Kim, Hong; Bien, Franklin; Young Lee, Chang; Park, Jang-Ung

2017-04-27

Wearable contact lenses which can monitor physiological parameters have attracted substantial interests due to the capability of direct detection of biomarkers contained in body fluids. However, previously reported contact lens sensors can only monitor a single analyte at a time. Furthermore, such ocular contact lenses generally obstruct the field of vision of the subject. Here, we developed a multifunctional contact lens sensor that alleviates some of these limitations since it was developed on an actual ocular contact lens. It was also designed to monitor glucose within tears, as well as intraocular pressure using the resistance and capacitance of the electronic device. Furthermore, in-vivo and in-vitro tests using a live rabbit and bovine eyeball demonstrated its reliable operation. Our developed contact lens sensor can measure the glucose level in tear fluid and intraocular pressure simultaneously but yet independently based on different electrical responses.

Wearable smart sensor systems integrated on soft contact lenses for wireless ocular diagnostics

NASA Astrophysics Data System (ADS)

Kim, Joohee; Kim, Minji; Lee, Mi-Sun; Kim, Kukjoo; Ji, Sangyoon; Kim, Yun-Tae; Park, Jihun; Na, Kyungmin; Bae, Kwi-Hyun; Kyun Kim, Hong; Bien, Franklin; Young Lee, Chang; Park, Jang-Ung

2017-04-01

Wearable contact lenses which can monitor physiological parameters have attracted substantial interests due to the capability of direct detection of biomarkers contained in body fluids. However, previously reported contact lens sensors can only monitor a single analyte at a time. Furthermore, such ocular contact lenses generally obstruct the field of vision of the subject. Here, we developed a multifunctional contact lens sensor that alleviates some of these limitations since it was developed on an actual ocular contact lens. It was also designed to monitor glucose within tears, as well as intraocular pressure using the resistance and capacitance of the electronic device. Furthermore, in-vivo and in-vitro tests using a live rabbit and bovine eyeball demonstrated its reliable operation. Our developed contact lens sensor can measure the glucose level in tear fluid and intraocular pressure simultaneously but yet independently based on different electrical responses.

Drug resistance profile and biofilm forming potential of Pseudomonas aeruginosa isolated from contact lenses in Karachi-Pakistan

PubMed Central

2013-01-01

Background The contaminated contact lens provides Pseudomonas aeruginosa an ideal site for attachment and biofilm production. Continuous contact of the eye to the biofilm-infested lens can lead to serious ocular diseases, such as keratitis (corneal ulcers). The biofilms also prevent effective penetration of the antibiotics, which increase the chances of antibiotic resistance. Methods For this study, 22 Pseudomonas aeruginosa isolates were obtained from 36 contact lenses and 14 contact lens protective fluid samples. These isolates were tested against eight commonly used antibiotics using Kirby-Bauer disk diffusion method. The biofilm forming potential of these isolates was also evaluated using various qualitative and quantitative techniques. Finally, a relationship between biofilm formation and antibiotic resistance was also examined. Results The isolates of Pseudomonas aeruginosa tested were found resistant to most of the antibiotics tested. Qualitative and quantitative biofilm analysis revealed that most of the isolates exhibited strong biofilm production. The biofilm production was significantly higher in isolates that were multi-drug resistant (p < 0.0001). Conclusion Our study indicates that multi-drug resistant, biofilm forming Pseudomonas aeruginosa isolates are mainly involved in contact lens associated infections. This appears to be the first report from Pakistan, which analyzes both antibiotic resistance profile and biofilm forming potential of Pseudomonas aeruginosa isolates from contact lens of the patients with contact lens associated infections. PMID:24134792

Contact lenses and the rate of evaporation measured in vitro; the influence of wear, squalene and wax.

PubMed

Vishnubhatla, Sravya; Borchman, Douglas; Foulks, Gary N

2012-12-01

Accelerated evaporation of tears may contribute to dry eye symptoms. It is not clear whether contact lenses decrease or increase the rate of evaporation of tears. In this study, the rates of evaporation through contact lenses (ERTCL) were measured in vitro to gain insight to this question. Contact lenses were equilibrated with various solutions to determine if they influenced ERTCL in vitro. ERTCL was measured gravimetrically. ERTCL measured in vitro for used contact lenses was about 20% faster than for buffer alone suggesting that natural tear components bound to the lenses changed the ERTCL. One natural tear component that binds to contact lenses is waxes. Equilibration of contact lenses with wax increased the ERTCL by about 30% suggesting that waxes might potentially increase ERTCL in vivo. Squalene, found in sebum and possibly meibum was infused into the contact lenses as a step toward decreasing the ERTCL. Squalene decreased ERTCL by over 60% in vitro. Soaking a contact lens in DuraSite(®) with benzalkonium chloride (BAK) did not alter the ERTCL. ERTCL were about 40% higher than the evaporation rate of DuraSite(®) alone or without BAK. In addition to lowering the ERTCL, the squalene in contact lenses could be a source of terpenoids to replace the terpenoids deficient in patients with MGD. If the ERTCL could be minimized in vivo, contact lenses could potentially be used to relieve dry eye symptoms in patients with evaporative dry eye. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Haemophilus influenzae adherent to contact lenses associated with production of acute ocular inflammation.

PubMed Central

Sankaridurg, P R; Willcox, M D; Sharma, S; Gopinathan, U; Janakiraman, D; Hickson, S; Vuppala, N; Sweeney, D F; Rao, G N; Holden, B A

1996-01-01

Ten episodes of adverse responses to contact lens wear, including contact lens-induced acute red eye (CLARE), in which Haemophilus influenzae was isolated from contact lenses and/or from one of the external ocular sites at the time of the event, are described. All episodes occurred in patients wearing disposable hydrogel lenses on a 6-night extended-wear schedule. Two of the patients had recurrent episodes. H. influenzae was usually isolated in large numbers, and other bacteria or fungi colonizing the contact lens or the external ocular surface were usually present in low numbers. Those patients who were colonized with H. influenzae were more than 100 times as likely to have had a CLARE or infiltrative response than those subjects who were not colonized with this bacterium. H. influenzae colonization of the contact lens and eye may be subsequent to colonization of the nasopharynx because four of the seven patients presented with fever at the time of the event, with concurrent upper respiratory tract infection. Contact lens wearers should be made aware of the potential risk of CLARE associated with the wearing of contact lenses for extended periods during and subsequent to upper respiratory tract infection. PMID:8880493

Activity of a melimine derived peptide Mel4 against Stenotrophomonas, Delftia, Elizabethkingia, Burkholderia and biocompatibility as a contact lens coating.

PubMed

Dutta, Debarun; Zhao, Timothy; Cheah, Kai Bing; Holmlund, Larke; Willcox, Mark D P

2017-06-01

To determine the antimicrobial activity of the melimine derived peptide Mel4 against Delftia, Stenotrophomonas, Elizabethkingia, Burkholderia and to investigate biocompatibility of Mel4 as an antimicrobial coating on contact lenses in animals and humans. In vitro antimicrobial activity of Mel4 was determined against the four Gram negative bacteria by investigating growth curves for 24h followed by viable counts to determine the minimum inhibitory concentration (MIC). Contact lenses were coated by covalently binding Mel4, characterized by amino acid analysis, and were investigated for changes in lens parameters. Safety of Mel-4 coated lenses were determined in a rabbit model of daily contralateral wear. A prospective, randomised, double-masked, contralateral, 1week daily wear human clinical trial was used to evaluate subjective responses and ocular physiology. Mel4 was active against all the bacteria tested (MIC 50 ranged from 31-1000μgml -1 ) and produced an antimicrobial surface on contact lenses. Mel4-coating resulted hydrophilic surface without any significant change in contact lens parameters, and showed no signs of cytotoxicity or ocular irritation during rabbit wear. During human clinical trial, there were no differences between Mel4 coated and uncoated contact lenses in lens performance indicators and ocular signs such as corneal fluorescein staining. Mel4 and control uncoated lenses had no differences in ocular symptoms during lens wear. Mel4 has achieved antimicrobial activity against variety of Gram negative bacteria that are often resistant to the action of cationic peptides and have been implicated in contact lens related adverse events. Mel4-coated contact lenses were safe to wear. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Immunoglobulin Concentration in Tears of Contact Lens Wearers

PubMed Central

Maurya, Rajendra P.; Bhushan, Prashant; Singh, Virendra P.; Singh, Mahendra K.; Kumar, Prakash; Bhatia, Ravindra P.S.; Singh, Usha

2014-01-01

Purpose: To evaluate changes in the concentration of tear immunoglobulins in contact lens wearers. Methods: A total of 45 cases including 23 contact lens wearers (43 eyes) and 22 age and sex matched healthy controls having no ocular pathology were studied for immunoglobulins (IgA, IgG, IgM) in their tears by single radial immunodiffusion method. Results: Most of the cases used soft (56.6%) and semi-soft gas permeable (30.4%) contact lenses. Tear IgM was detected in only 17.4% and tear IgG in 43.6% of contact lens wearers, while in controls IgG was detected in 9.1% but none of the controls had IgM. There was a significant rise in total tear IgA (13.17 ± 4.44 mg/dl) in contact lens wearer as compared to controls (8.93 ± 3.79 mg/dl). Rise of tear IgA was more in symptomatic patients (15.38 ± 5.28 mg/dl) and in those wearing hard (19.73 ± 5.43 mg/dl) and semi-soft contact lenses (13.31 ± 5.43 mg/dl). A significant increase in tear IgA was noticed in subjects wearing lenses for >3 years (15.69 ± 5.39 mg/dl). About 43.4% of lens wearers were symptomatic and 80% of their lenses showed deposits and/or haziness. All cases with IgM in tear were symptomatic. Conclusion: The relation of immunoglobulin concentration with increasing duration of wear and material of contact lens shows that tear immunoglobulin rise accrues due to mechanical stimulation, hence contact lenses should not be used for a long period and lenses of hard nature should be discouraged. The maintenance, cleaning and deproteinization of the lenses are of high importance to avoid immunostimulation. PMID:25667732

Latanoprost-Eluting Contact Lenses in Glaucomatous Monkeys.

PubMed

Ciolino, Joseph B; Ross, Amy E; Tulsan, Rehka; Watts, Amy C; Wang, Rong-Fang; Zurakowski, David; Serle, Janet B; Kohane, Daniel S

2016-10-01

To assess the ability of latanoprost-eluting contact lenses to lower the intraocular pressure (IOP) of glaucomatous eyes of cynomolgus monkeys. Preclinical efficacy study of 3 treatment arms in a crossover design. Female cynomolgus monkeys with glaucoma induced in 1 eye by repeated argon laser trabeculoplasty. Latanoprost-eluting low-dose contact lenses (CLLO) and high-dose contact lenses (CLHI) were produced by encapsulating a thin latanoprost-polymer film within the periphery of a methafilcon hydrogel, which was lathed into a contact lens. We assessed the IOP-lowering effect of CLLO, CLHI, or daily latanoprost ophthalmic solution in the same monkeys. Each monkey consecutively received 1 week of continuous-wear CLLO, 3 weeks without treatment, 5 days of latanoprost drops, 3 weeks without treatment, and 1 week of continuous-wear CLHI. On 2 consecutive days before initiation of each study arm, the IOP was measured hourly over 7 consecutive hours to establish the baseline IOP. Two-tailed Student t tests and repeated-measures analysis of variance were used for statistical analysis. Intraocular pressure. Latanoprost ophthalmic solution resulted in IOP reduction of 5.4±1.0 mmHg on day 3 and peak IOP reduction of 6.6±1.3 mmHg on day 5. The CLLO reduced IOP by 6.3±1.0, 6.7±0.3, and 6.7±0.3 mmHg on days 3, 5, and 8, respectively. The CLHI lowered IOP by 10.5±1.4, 11.1±4.0, and 10.0±2.5 mmHg on days 3, 5, and 8, respectively. For the CLLO and CLHI, the IOP was statistically significantly reduced compared with the untreated baseline at most time points measured. The CLHI demonstrated greater IOP reduction than latanoprost ophthalmic solution on day 3 (P = 0.001) and day 5 (P = 0.015), and at several time points on day 8 (P < 0.05). Sustained delivery of latanoprost by contact lenses is at least as effective as delivery with daily latanoprost ophthalmic solution. More research is needed to determine the optimal continuous-release dose that would be well tolerated and maximally effective. Contact lens drug delivery may become an option for the treatment of glaucoma and a platform for ocular drug delivery. Copyright © 2016 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Evaluation of glutaraldehyde and povidone iodine for sterilization of wide-field contact vitrectomy lenses.

PubMed

Das, T; Sharma, S; Singh, J; Rao, V; Chalam, K V

2001-01-01

Wide-field vitrectomy contact lenses are currently sterilized with ethylene oxide gas, and other lenses with autoclaving. To maintain a large inventory or possibly run the risk of loss of lens quality with repeated autoclaving, glutaraldehyde 2% and povidone iodine 5% solution were evaluated as possible sterilizing agents. Ethylene oxide presterilized lenses were contaminated with known concentrations (10(5) organisms/mL) of bacteria (S. epidemidis, P. aeruginosa, B. subtilis), and fungi (A. flavus, C. albicans) for 5 minutes. The test lenses were treated with glutaraldehyde or povidone iodine for 5, 10, 30, 60, and 120 minutes, and controls with sterilized water for a similar duration. Following treatment, both test and control lenses were sampled with sterile cotton swabs. The swabs were cultured for bacteria (tryptone soya broth 48 hours), and fungi (Saubourd's dextrose broth 5 days). The culture was negative for both glutaraldehyde- and povidone iodine-treated lenses against all organisms at all time points except B subtilis, which needed 120 minutes treatment. Two hours contact time with glutaraldehyde 2% or providone iodine 5% can sterilize vitrectomy contact lenses against common bacteria and fungi without affecting lens quality.

First contact diagnosis and management of contact lens-related complications.

PubMed

Fagan, Xavier J; Jhanji, Vishal; Constantinou, Marios; Amirul Islam, F M; Taylor, Hugh R; Vajpayee, Rasik B

2012-08-01

To describe the spectrum of contact lens-related problems in cases presenting to a tertiary referral eye hospital. A retrospective case record analysis of 111 eyes of 97 consecutive patients was undertaken over a period of five months at the Royal Victorian Eye and Ear Hospital, Melbourne, Australia. Contact lens-related complications (CLRC) were classified into microbial keratitis, sterile corneal infiltrates, corneal epitheliopathy and contact lens-related red eye (CLARE). Main parameters examined were nature of the first contact, clinical diagnosis, and management pattern. Forty-two percent of the initial presentations were to health care practitioners (HCPs) other than ophthalmologists. Mean duration from the onset of symptoms to presentation was 6.3 ± 10.9 days. Forty-nine percent (n = 54) of patients had an associated risk factor, most commonly overnight use of contact lenses (n = 14, 13 %). Most common diagnosis at presentation was corneal epitheliopathy (68 %) followed by sterile infiltrates (10 %), CLARE (8 %) and microbial keratitis (6 %). No significant differences were found in the pattern of treatment modalities administered by ophthalmologists and other HCPs. HCPs other than ophthalmologists are the first contact for contact lens-related problems in a significant proportion of patients. These HCPs manage the majority of CLRC by direct treatment or immediate referral.

Cytokine changes in tears and relationship to contact lens discomfort

PubMed Central

Zhao, Zhenjun; Naduvilath, Thomas; Lazon de la Jara, Percy

2015-01-01

Purpose To determine the reproducibility of a multiplex bead assay for measuring cytokines in tears and correlations between ocular discomfort with or without contact lens wear and the concentration of cytokines in tears. Methods Ninety participants (divided into two groups) were enrolled in this prospective study. They were asked to rate their ocular comfort and collect their tears in the morning and just before sleep for 10 days with or without contact lenses. The participants collected their tears using a glass microcapillary tube for both stages. Galyfilcon A lenses were worn on a daily disposable basis during the contact lens stage, and comfort scores and tears were collected before lens insertion and prior to lens removal at the end of the day. Tears were analyzed for cytokine concentrations using a 27-plex multibead assay. Correlations were sought between cytokine concentrations and comfort. Results There was a significant (p<0.022) decrease in ocular comfort over the day with or without lens wear. The magnitude of ocular discomfort was significantly greater (p<0.009) with lens wear. The concentrations of 12 cytokines differed significantly between the groups; thus, these cytokines were not analyzed further. For the remaining 15 cytokines, interleukin-8 (IL-8) was the only cytokine that changed in both groups during the day without (reduced by >-0.5 Log pg/ml, p<0.001) or with lens wear (reduced by >-0.2 Log pg/ml, p<0.001). The change in the vascular endothelial growth factor (VEGF) concentration only in tears was correlated to ocular comfort, but this was not changed by contact lens wear. Conclusions Ocular comfort during the day is magnified by contact lens wear. However, the increase in the change in comfort during lens wear was not associated with changes in 15 cytokines in the tear film. PMID:25814827

Which soft lens power is better for piggyback in keratoconus? Part II.

PubMed

Romero-Jiménez, Miguel; Santodomingo-Rubido, Jacinto; González-Meijóme, Jose-Manuel; Flores-Rodriguez, Patricia; Villa-Collar, Cesar

2015-02-01

To evaluate how soft lens power affects rigid gas-permeable (RGP) lens power and visual acuity (VA) in piggyback fittings for keratoconus. Sixteen keratoconus subjects (30 eyes) were included in the study. Piggyback contact lens fittings combining Senofilcon-A soft lenses of -6.00, -3.00, +3.00 and +6.00 D with Rose K2 RGP contact lenses were performed. Corneal topography was taken on the naked eye and over each soft contact lens before fitting RGP lenses. Mean central keratometry, over-refraction, RGP back optic zone radius (BOZR) and estimated final power as well as VA were recorded and analyzed. In comparison to the naked eye, the mean central keratometry flattened with both negative lens powers (p<0.05 in all cases), did not change with the +3.00 soft lens power (p=1.0); and steepened with the +6.00 soft lens power (p=0.02). Rigid gas-permeable over-refraction did not change significantly between different soft lens powers (all p>0.05). RGP's BOZR decreased significantly with both positive in comparison with both negative soft lens powers (all p<0.001), but no significant differences were found among negative- or positive-powers separately (both p>0.05). Estimated RGP's final power increased significantly with positive in comparison with negative lens powers (all p<0.001), but no significant differences were found among negative or positive lens powers separately (both p>0.05). Visual acuity did not change significantly between the different soft lens powers assessed (all p>0.05). The use of negative-powered soft lenses in piggyback fitting reduces RGP lens power without impacting VA in keratoconus subjects. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Deposition of lipid, protein, and secretory phospholipase A2 on hydrophilic contact lenses.

PubMed

Mochizuki, Hiroshi; Yamada, Masakazu; Hatou, Shin; Kawashima, Motoko; Hata, Seiichiro

2008-01-01

Recent studies have shown that low tear phospholipid levels are associated with tear film instability in hydrophilic contact lens wearers. The concentration of secretory phospholipase A2 (sPLA2), the enzyme that hydrolyzes phospholipids, in tears is known to exceed the levels found in serum by four orders of magnitude. This study was performed to determine the levels of sPLA2 from the deposition on two different frequent-replacement contact lens materials. Polymacon and etafilcon A contact lenses worn for 2 weeks by 16 experienced contact lens wearers were used for the analysis. Total lipids were determined by the sulfo-phospho-vanillin reaction. Phospholipids in lipid extracts were estimated by phosphorus determination with ammonium molybdate through enzymatic digestion. Total protein was measured by bicinchoninic acid analysis. Double-antibody sandwich enzyme-linked immunosorbent assay was used to determine sPLA2 concentrations. Total lipid deposition was found to be greater in the polymacon group (66.3+/-16.3 microg/lens) than in the etafilcon A group, although phospholipids were not detected in either group. The etafilcon A group had greater deposition of protein (3.7+/-0.7 mg/lens) than the polymacon group had. The etafilcon A group deposited statistically significantly more group IIa sPLA2 (1.1+/-0.3 microg/lens) than the polymacon group (0.07+/-0.04 microg/lens) did (P<0.001). There was a significant difference in the lipid and protein deposition profiles in the two lenses tested. A significant amount of sPLA2 in the deposition on contact lenses may play a role in tear film instability in hydrophilic contact lens wearers.

The significance of oxygen during contact lens wear.

PubMed

Papas, Eric B

2014-12-01

In order to establish the relevance of oxygen to contemporary contact lens practice, a review of the literature was conducted. The results indicate that there are a number of processes occurring in the normal healthy eye where oxygen is required and which are potentially affected by the presence of a contact lens. These activities appear to take place at all corneal levels, as well as at the limbus. Evidence from laboratory, clinical and modelling studies indicates that what constitutes normal oxygenation (normoxia) depends on, among other things, the physiological system under consideration, corneal location and the state of eye closure. This diversity is reflected in the wide range of minimum lens oxygen transmissibility (Dk/t) requirements that are present in a literature. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Microbial Keratitis: Could Contact Lens Material Affect Disease Pathogenesis?

PubMed Central

Evans, David J.; Fleiszig, Suzanne M. J.

2012-01-01

Microbial keratitis is a sight-threatening complication associated with contact lenses. The introduction of silicone hydrogel lens materials with increased oxygen transmission to the ocular surface has not significantly altered the incidence of microbial keratitis. These data suggest that alternate, or additional, predisposing factors involving lens wear must be addressed to reduce or eliminate these infections. The contact lens can provide a surface for microbial growth in situ, and can also influence ocular surface homeostasis through effects on the tear fluid and corneal epithelium. Thus, it is intuitive that future contact lens materials could make a significant contribution to preventing microbial keratitis. Design of the “right” material to prevent microbial keratitis requires understanding the effects of current materials on bacterial virulence in the cornea, and on ocular surface innate defenses. Current knowledge in each of these areas will be presented, with a discussion of future directions needed to understand the influence of lens material on the pathogenesis of microbial keratitis. PMID:23266587

A portable non-contact displacement sensor and its application of lens centration error measurement

NASA Astrophysics Data System (ADS)

Yu, Zong-Ru; Peng, Wei-Jei; Wang, Jung-Hsing; Chen, Po-Jui; Chen, Hua-Lin; Lin, Yi-Hao; Chen, Chun-Cheng; Hsu, Wei-Yao; Chen, Fong-Zhi

2018-02-01

We present a portable non-contact displacement sensor (NCDS) based on astigmatic method for micron displacement measurement. The NCDS are composed of a collimated laser, a polarized beam splitter, a 1/4 wave plate, an aspheric objective lens, an astigmatic lens and a four-quadrant photodiode. A visible laser source is adopted for easier alignment and usage. The dimension of the sensor is limited to 115 mm x 36 mm x 56 mm, and a control box is used for dealing with signal and power control between the sensor and computer. The NCDS performs micron-accuracy with +/-30 μm working range and the working distance is constrained in few millimeters. We also demonstrate the application of the NCDS for lens centration error measurement, which is similar to the total indicator runout (TIR) or edge thickness difference (ETD) of a lens measurement using contact dial indicator. This application has advantage for measuring lens made in soft materials that would be starched by using contact dial indicator.

In vivo performance of melimine as an antimicrobial coating for contact lenses in models of CLARE and CLPU.

PubMed

Cole, Nerida; Hume, Emma B H; Vijay, Ajay K; Sankaridurg, Padmaja; Kumar, Naresh; Willcox, Mark D P

2010-01-01

One strategy to minimize bacteria-associated adverse responses such as microbial keratitis, contact lens-induced acute red eye (CLARE), and contact lens induced peripheral ulcers (CLPUs) that occur with contact lens wear is the development of an antimicrobial or antiadhesive contact lens. Cationic peptides represent a novel approach for the development of antimicrobial lenses. A novel cationic peptide, melimine, was covalently incorporated into silicone hydrogel lenses. Confirmation tests to determine the presence of peptide and anti-microbial activity were performed. Cationic lenses were then tested for their ability to prevent CLPU in the Staphylococcus aureus rabbit model and CLARE in the Pseudomonas aeruginosa guinea pig model. In the rabbit model of CLPU, melimine-coated lenses resulted in significant reductions in ocular symptom scores and in the extent of corneal infiltration (P < 0.05). Evaluation of the performance of melimine lenses in the CLARE model showed significant improvement in all ocular response parameters measured, including the percentage of eyes with corneal infiltrates, compared with those observed in the eyes fitted with the control lens (P < or = 0.05). Cationic coating of contact lenses with the peptide melimine may represent a novel method of prevention of bacterial growth on contact lenses and consequently result in reduction of the incidence and severity of adverse responses due to Gram-positive and -negative bacteria during lens wear.

External ocular surface and lens microbiota in contact lens wearers with corneal infiltrates during extended wear of hydrogel lenses.

PubMed

Willcox, Mark; Sharma, Savitri; Naduvilath, Thomas J; Sankaridurg, Padmaja R; Gopinathan, Usha; Holden, Brien A

2011-03-01

To determine whether carriage of microbes on the contact lens or ocular surfaces during extended wear (EW) with soft hydroxyethyl methacrylate (HEMA)-based contact lenses predisposes the wearer to adverse events. Participants (non-contact lens wearers) were enrolled in a clinical study involving wear of HEMA-based hydrogel lenses on a six night EW basis with weekly replacement. Type and number of bacteria colonizing the lower lid margins, upper bulbar conjunctiva, and contact lenses during EW after one night, 1 week, 1 month, and thereafter every 3 months for 3.5 years were determined. The association of bacteria with adverse responses was compared between carriers (defined as having significant microbes cultured from two or more samples with 1 year) and noncarriers, and the strength of the association was estimated using multivariate logistic regression. Carriers of gram-positive bacteria on lenses (particularly coagulase negative staphylococci or Corynebacterium spp.) were approximately three and eight times more likely to develop contact lens-induced peripheral ulcers (CLPUs) and asymptomatic infiltrates (AIs), respectively. Staphylococcus aureus was most frequently isolated from lenses during CLPU. Carriers of gram-negative bacteria on lenses were five times more likely to develop contact lens-induced acute red eye (CLARE). Haemophilus influenzae was isolated most frequently from lenses during CLARE and AI events. Bacterial carriage on contact lenses during EW predisposes the wearer to the development of corneal inflammatory events including CLARE, CLPU, and AI.

Phospholipids and their degrading enzyme in the tears of soft contact lens wearers.

PubMed

Yamada, Masakazu; Mochizuki, Hiroshi; Kawashima, Motoko; Hata, Seiichiro

2006-12-01

Low tear phospholipids levels are associated with tear film instability in soft contact lens wearers. We assayed levels of phospholipids and their degrading enzyme secretory phospholipase A2 (sPLA2) both in tears and deposited on contact lenses composed of 2 hydrophilic materials after 1 day of routine use. Polymacon (Medalist; FDA group 1, low water/nonionic) and Etafilcon A (One Day Acuvue; group 4, high water/ionic) contact lenses were worn for 12 hours by 16 experienced contact lens wearers. Phospholipids in tear fluids and deposited on contact lenses were estimated by phosphorus determination with ammonium molybdate through enzymatic digestion. Double-antibody sandwich ELISA was used to determine group IIa sPLA2 concentrations, and sPLA2 activity was assayed using 1,2-diheptanoyl thio-phosphatidylcholine as substrate. Phospholipids concentrations in tears with Polymacon and Etafilcon A were 186 +/- 39 and 162 +/- 33 microg/mL, respectively. The latter concentration was significantly lower than that observed in the same subjects when not wearing contact lenses (P = 0.0023). In tears, both group IIa sPLA2 concentrations and enzymatic activity remained unchanged, regardless of lens wearing. However, Etafilcon A (0.57 +/- 0.09 microg/lens) showed more group IIa sPLA2 deposition than Polymacon (0.01 +/- 0.01 microg/lens; P < 0.001). Furthermore, group IIa sPLA2 deposited on Etafilcon A but not on Polymacon lenses retained its enzymatic activity. Significant differences of group IIa sPLA2 deposition were found in the 2 lenses tested. Such deposition might induce phospholipid hydrolysis in tears and thereby promote tear film instability in hydrophilic contact lens wearers.

Contact lens-related dry eye and ocular surface changes with mapping technique in long-term soft silicone hydrogel contact lens wearers.

PubMed

Sengor, Tomris; Aydin Kurna, Sevda; Ozbay, Nurver; Ertek, Semahat; Aki, Suat; Altun, Ahmet

2012-01-01

To evaluate ocular surface changes in long-term silicone hydrogel contact lens wearers. Thirty patients were included in this study. Twenty patients (40 eyes) using contact lenses constituted group 1 and 10 (20 eyes) volunteers constituted group 2. The duration of average contact lens usage was 7.74 ± 3.3 years. Ocular surface was evaluated by surface staining, tear film break-up time (TBUT), Schirmer I test, and conjunctival impression cytology with color-coded mapping technique and by the Ocular Surface Disease Index (OSDI). The mean break-up time was lower and staining scores were higher in group 1 (p<0.001) but Schirmer values were not significantly different from group 2 (p>0.05). The mean OSDI score was 34.59 ± 11.93 to 19.28 ± 6.7 in group 1 and 2. Increased metaplastic predominant changes of grade II and III were observed in the interpalpebral and perilimbal areas in group 1. Significant correlations were observed in TBUT, cornea staining, and grade II to grade III metaplasia ratios between duration of the lens usage and contact lens wear time in a day. Silicone hydrogel lenses produce significant changes on tear film and impression cytology of the ocular surface in long-term use.

Assessment of modifications in thickness, curvatures, and volume upon the cornea caused by disposable soft contact lens wear.

PubMed

Del Águila-Carrasco, Antonio J; Domínguez-Vicent, Alberto; Pérez-Vives, Cari; Ferrer-Blasco, Teresa; Montés-Micó, Robert

2015-01-01

To assess the effect of different disposable soft contact lenses on several corneal parameters-thickness, anterior and posterior curvature, and volume-by means of a Scheimpflug imaging-based device (Pentacam HR). Diurnal variations of these parameters were taken into account. Twenty-one young, healthy subjects wore 4 different types of daily disposable soft contact lenses on 4 different days: Dailies AquaComfort Plus, SofLens, Dailies Total1, and Acuvue TruEye. The lenses had different material and water content. Pachymetry and curvature maps and corneal volume values were obtained using the Pentacam HR twice a day: one before putting the lens on and one after an 8-hour period of contact lens wear. Measurements were also taken without any contact lenses being worn. Regarding corneal thickness, the lens with the most similar behavior to the naked eye scenario was the Dailies Total1, causing a thickening of 0.2 ± 0.1% in the central zone and 0.6 ± 0.2% in the periphery. All 4 lenses caused a slight but not significant flattening in the anterior corneal curvature, whereas the posterior corneal curvature only experienced a significant but small steepening with the SofLens. The use of these lenses increased corneal volume slightly. Variations in corneal parameters seem to depend on the type of contact lens used (material, oxygen transmissibility, water content). However, the magnitude of the changes introduced by the use of soft contact lenses over the 8-hour period was small and probably not large enough to influence either visual acuity or comfort.

Computational Sensing of Staphylococcus aureus on Contact Lenses Using 3D Imaging of Curved Surfaces and Machine Learning.

PubMed

Veli, Muhammed; Ozcan, Aydogan

2018-03-27

We present a cost-effective and portable platform based on contact lenses for noninvasively detecting Staphylococcus aureus, which is part of the human ocular microbiome and resides on the cornea and conjunctiva. Using S. aureus-specific antibodies and a surface chemistry protocol that is compatible with human tears, contact lenses are designed to specifically capture S. aureus. After the bacteria capture on the lens and right before its imaging, the captured bacteria are tagged with surface-functionalized polystyrene microparticles. These microbeads provide sufficient signal-to-noise ratio for the quantification of the captured bacteria on the contact lens, without any fluorescent labels, by 3D imaging of the curved surface of each lens using only one hologram taken with a lens-free on-chip microscope. After the 3D surface of the contact lens is computationally reconstructed using rotational field transformations and holographic digital focusing, a machine learning algorithm is employed to automatically count the number of beads on the lens surface, revealing the count of the captured bacteria. To demonstrate its proof-of-concept, we created a field-portable and cost-effective holographic microscope, which weighs 77 g, controlled by a laptop. Using daily contact lenses that are spiked with bacteria, we demonstrated that this computational sensing platform provides a detection limit of ∼16 bacteria/μL. This contact-lens-based wearable sensor can be broadly applicable to detect various bacteria, viruses, and analytes in tears using a cost-effective and portable computational imager that might be used even at home by consumers.

Optical edge effects create conjunctival indentation thickness artefacts.

PubMed

Sorbara, Luigina; Simpson, Trefford L; Maram, Jyotsna; Song, Eun Sun; Bizheva, Kostadinka; Hutchings, Natalie

2015-05-01

Conjunctival compression observed in ultrahigh resolution optical coherence tomography (UHR-OCT) images of contact lens edges could be actual tissue alteration, may be an optical artefact arising from the difference between the refractive indexes of the lens material and the conjunctival tissue, or could be a combination of the two. The purpose of this study is to image the artefact with contact lenses on a non-biological (non-indentable) medium and to determine the origins of the observed conjunctival compression. Two-dimensional cross-sectional images of the edges of a selection of marketed silicone hydrogel and hydrogel lenses (refractive index ranging from 1.40 to 1.43) were acquired with a research grade UHR-OCT system. The lenses were placed on three continuous surfaces, a glass sphere (refractive index n = 1.52), a rigid contact lens (n = 1.376) and the cornea of a healthy human subject (average n = 1.376). The displacement observed was analysed using ImageJ. The observed optical displacement ranged between 5.39(0.06) μm with Acuvue Advance and 11.99(0.18) μm with Air Optix Night & Day when the lens was imaged on the glass reference sphere. Similarly, on a rigid contact lens displacement ranged between 5.51(0.03) and 9.72(0.12) μm. Displacement was also observed when the lenses were imaged on the human conjunctiva and ranged from 6.49(0.80) μm for the 1-day Acuvue Moist to 17.4(0.22) μm for the Pure Vision contact lens. An optical displacement artefact was observed when imaging a contact lens on two rigid continuous surfaces with UHR-OCT where compression or indentation of the surface could not have been a factor. Contact lenses imaged in situ also exhibited displacement at the intersection of the contact lens edge and the conjunctiva, likely a manifestation of both the artefact and compression of the conjunctiva. © 2015 The Authors Ophthalmic & Physiological Optics © 2015 The College of Optometrists.

Predicting success with silicone-hydrogel contact lenses in new wearers.

PubMed

Best, Nigel; Drury, Laura; Wolffsohn, James S

2013-10-01

to evaluate changes in tear metrics and ocular signs induced by six months of silicone-hydrogel contact lens wear and the difference in baseline characteristics between those who successfully continued in contact lens wear compared to those that did not. Non-invasive Keratograph, Tearscope and fluorescein tear break-up times (TBUTs), tear meniscus height, bulbar and limbal hyperaemia, lid-parallel conjunctival folds (LIPCOF), phenol red thread, fluorescein and lissamine-green staining, and lid wiper epitheliopathy were measured on 60 new contact lens wearers fitted with monthly silicone-hydrogels (average age 36±14 years, 40 females). Symptoms were evaluated by the Ocular Surface Disease Index (OSDI). After six months full time contact lens wear the above metrics were re-measured on those patients still in contact lens wear (n=33). The initial measurements were also compared between the group still wearing lenses after six months and those who had ceased lens wear (n=27). There were significant changes in tear meniscus height (p=0.031), bulbar hyperaemia (p=0.011), fluorescein TBUT (p=0.027), corneal (p=0.007) and conjunctival (p=0.009) staining, LIPCOF (p=0.011) and lid wiper epitheliopathy (p=0.002) after six months of silicone-hydrogel wear. Successful wearers had a higher non-invasive (17.0±8.2s vs 12.0±5.6s; p=0.001) and fluorescein (10.7±6.4s vs 7.5±4.7s; p=0.001) TBUT than drop-outs, although OSDI (cut-off 4.2) was also a strong predictor of success. Silicone-hydrogel lenses induced significant changes in the tear film and ocular surface as well as lid margin staining. Wettability of the ocular surface is the main factor affecting contact lens drop-out. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

38 CFR 4.77 - Visual fields.

Code of Federal Regulations, 2011 CFR

2011-07-01

... who are well adapted to intraocular lens implant or contact lens correction, visual field examinations.... For aphakic individuals not well adapted to contact lens correction or pseudophakic individuals not... meridians 221/2 degrees apart for each eye and indicate the Goldmann equivalent used. See Table III for the...

38 CFR 4.77 - Visual fields.

Code of Federal Regulations, 2010 CFR

2010-07-01

... who are well adapted to intraocular lens implant or contact lens correction, visual field examinations.... For aphakic individuals not well adapted to contact lens correction or pseudophakic individuals not... meridians 221/2 degrees apart for each eye and indicate the Goldmann equivalent used. See Table III for the...

Corneal and conjunctival sensory function: the impact on ocular surface sensitivity of change from low to high oxygen transmissibility contact lenses.

PubMed

Golebiowski, Blanka; Papas, Eric B; Stapleton, Fiona

2012-03-09

Deprivation of oxygen to the ocular surface during contact lens wear has been implicated in the alteration of sensory function. This study investigates whether increasing oxygen availability through discontinuation of contact lens wear or transfer into highly oxygen transmissible (high Dk/t) lenses leads to a change in corneal or conjunctival sensitivity. Twenty-seven long-term extended wearers of low Dk/t soft contact lenses ceased lens wear for 1 week and were refitted with high Dk/t silicone hydrogel lenses. A control group of 25 nonwearers matched for age and sex was also recruited. Central corneal and inferior conjunctival sensitivity were measured using an air-jet aesthesiometer. Threshold was determined using a staircase technique. Measurements were taken during low Dk/t lens wear; after 1 week of no wear; and after 1, 3, 6, and 12 months of high Dk/t lens wear. Measurements were carried out on one occasion on the nonwearers. Corneal sensitivity decreased 1 week after discontinuation of low Dk/t lenses and no further change in sensitivity occurred with high Dk/t lens wear. Conjunctival sensitivity did not change over the same time frame. Ocular surface sensitivity in long-term low Dk/t soft lens wearers was similar to that of nonwearers. Sensitivity was higher in females than males in the nonwearers, but not in the lens-wearing group. An interaction of sex on change in conjunctival threshold was found in the lens wearers. These findings indicate that factors other than oxygen availability alone determine sensitivity of the ocular surface. Silicone hydrogel contact lenses appear to have only a minor impact on ocular surface sensitivity in previous lens wearers.

Factors influencing bacterial adhesion to contact lenses.

PubMed

Dutta, Debarun; Cole, Nerida; Willcox, Mark

2012-01-01

The process of any contact lens related keratitis generally starts with the adhesion of opportunistic pathogens to contact lens surface. This article focuses on identifying the factors which have been reported to affect bacterial adhesion to contact lenses. Adhesion to lenses differs between various genera/species/strains of bacteria. Pseudomonas aeruginosa, which is the predominant causative organism, adheres in the highest numbers to both hydrogel and silicone hydrogel lenses in vitro. The adhesion of this strain reaches maximum numbers within 1h in most in vitro studies and a biofilm has generally formed within 24 h of cells adhering to the lens surface. Physical and chemical properties of contact lens material affect bacterial adhesion. The water content of hydroxyethylmethacrylate (HEMA)-based lenses and their iconicity affect the ability of bacteria to adhere. The higher hydrophobicity of silicone hydrogel lenses compared to HEMA-based lenses has been implicated in the higher numbers of bacteria that can adhere to their surfaces. Lens wear has different effects on bacterial adhesion, partly due to differences between wearers, responses of bacterial strains and the ability of certain tear film proteins when bound to a lens surface to kill certain types of bacteria.

Factors influencing bacterial adhesion to contact lenses

PubMed Central

Dutta, Debarun; Willcox, Mark

2012-01-01

The process of any contact lens related keratitis generally starts with the adhesion of opportunistic pathogens to contact lens surface. This article focuses on identifying the factors which have been reported to affect bacterial adhesion to contact lenses. Adhesion to lenses differs between various genera/species/strains of bacteria. Pseudomonas aeruginosa, which is the predominant causative organism, adheres in the highest numbers to both hydrogel and silicone hydrogel lenses in vitro. The adhesion of this strain reaches maximum numbers within 1h in most in vitro studies and a biofilm has generally formed within 24 h of cells adhering to the lens surface. Physical and chemical properties of contact lens material affect bacterial adhesion. The water content of hydroxyethylmethacrylate (HEMA)-based lenses and their iconicity affect the ability of bacteria to adhere. The higher hydrophobicity of silicone hydrogel lenses compared to HEMA-based lenses has been implicated in the higher numbers of bacteria that can adhere to their surfaces. Lens wear has different effects on bacterial adhesion, partly due to differences between wearers, responses of bacterial strains and the ability of certain tear film proteins when bound to a lens surface to kill certain types of bacteria. PMID:22259220

The impact of cellular debris on Pseudomonas aeruginosa adherence to silicone hydrogel contact lenses and contact lens storage cases.

PubMed

Burnham, Geoffrey W; Cavanagh, H Dwight; Robertson, Danielle M

2012-01-01

To evaluate neutrophil-enhanced Pseudomonas aeruginosa (PA) biofilm formation on silicone hydrogel contact lenses and to determine the effect of epithelial biodebris on PA adherence in contact lens storage cases. A fully invasive PA corneal isolate stably conjugated to green fluorescent protein was used. Unworn lotrafilcon A contact lenses were incubated at various ratios of PA to polymorphonuclear neutrophil (PMN) for 24 hours at 37°C. Lens-associated PA was evaluated using laser scanning confocal microscopy and nonviable PA were visualized using propidium iodide. Viable bacteria were enumerated by colony-forming unit (CFU) analysis. For acute epithelial cell studies, PA viability was determined after coincubation with freeze-thaw epithelial cell lysates in 96-well polystyrene plates. Levels of residual cellular debris and bacterial viability were further assessed in used contact lens storage cases. Laser scanning confocal microscopy demonstrated that cotreatment with PMA-stimulated neutrophils increased PA adherence over 24 hours to lens surfaces with a striking alteration of PA architecture. Propidium iodide staining showed that the adherent bacteria consisted of a mixture of viable and nonviable PA; a PMN-associated increase in viable PA was confirmed by CFU (PA:PMN 0.1:1, P = 0.025; PA:PMN 1:1, P = 0.005). Acute epithelial cell debris studies revealed a significant increase in viable PA in 96-well plates in the presence of epithelial freeze-thaw lysates (PA:debris 1:1, P = 0.002; PA:debris 100:1, P = 0.002). Crystal violet staining of used lens storage cases revealed residual cellular debris at all time points, which was independent of microbial contamination; all lens cases used for periods of 9 months or more were uniformly associated with high levels of viable microorganisms. These results demonstrate that prolonged corneal inflammation with the presence of PMNs when confronted with simultaneous PA challenge in extended contact lens wear has the potential to stimulate biofilm formation on silicone hydrogel contact lenses. These findings further suggest that a persistent buildup of extracellular debris in lens storage cases may contribute to the heavy biofilms reported on these surfaces.

Performance evaluation of delefilcon a water gradient daily disposable contact lenses in first-time contact lens wearers.

PubMed

Marx, Sebastian; Lauenborg, Bo; Kern, Jami R

2018-02-06

To evaluate the tolerability of and subject and investigator satisfaction with delefilcon A (DAILIES TOTAL1 ® ) daily disposable contact lenses in first-time contact lens wearers. This European multicenter, open-label, single-arm, two-week trial enrolled first-time contact lens wearers and fitted them with delefilcon A contact lenses. Assessments were made at dispensing and at Weeks 1 and 2. Subject-reported outcomes included comfort, quality of vision, convenience, and intent to purchase, which were ranked by agreement responses. Investigator-reported outcomes included slit-lamp biomicroscopy findings and lens fit satisfaction. Ninety-two subjects were included in the per protocol dataset. Mean scores at Weeks 1 and 2 for subject-reported quality of vision and ocular comfort were significantly higher with delefilcon A contact lenses than with the subjects' habitual spectacles during the day, at the end of the day, and overall (all p ≤ 0.02). Ninety-one percent of subjects reported that their study lenses were more comfortable than expected, 98% agreed that they were convenient to use, and 92% were interested in purchasing the lenses (all p < 0.001). Investigators reported that study lenses had an acceptable fit in at least 97% of subjects. Practitioners can expect favorable outcomes when transitioning first-time contact lens wearers from spectacles to delefilcon A daily disposable contact lenses. Copyright © 2017. Published by Elsevier Ltd.

Oral omega-6 essential fatty acid treatment in contact lens associated dry eye.

PubMed

Kokke, Karolien H; Morris, Judith A; Lawrenson, John G

2008-06-01

Symptoms of dry eye are commonly reported in contact lens wearers and are a frequent cause of non-tolerance. The purpose of the present study is to evaluate the effects of oral treatment with particular omega-6 fatty acids in the form of evening primrose oil (EPO) on subjective symptoms, ocular surface signs and tear film characteristic in patients with contact lens associated dry eye. The study design was randomised, double-masked and placebo controlled. 76 female soft contact lens wearers were treated for 6 months with either EPO or placebo (olive oil). Subjects underwent three examinations (baseline, 3 and 6 months). At each examination subjects were given a questionnaire relating to lens comfort and dry eye symptoms and underwent a series of tests of tear film characteristics (tear meniscus height, break-up time), meibomian gland function (lipid layer thickness and quality) and ocular surface parameters (hyperaemia and staining). The EPO group showed a significant improvement in the specific symptom of 'dryness' at 3 and 6 months (p<0.01) and also a significant improvement in overall lens comfort at 6 months (p<0.01). Tear meniscus height was increased in the EPO group at 6 months relative to baseline (p<0.01), although all other objective signs were unchanged. This study provides evidence for a beneficial effect of particular orally administered omega-6 fatty acids in alleviating dry eye symptoms and improving overall lens comfort in patients suffering from contact lens associated dry eye.

Contact lens material characteristics associated with hydrogel lens dehydration.

PubMed

Ramamoorthy, Padmapriya; Sinnott, Loraine T; Nichols, Jason J

2010-03-01

To determine the association between material dehydration and hydrogel contact lens material characteristics, including water content and ionicity. Water content and refractive index data were derived from automated refractometry measurements of worn hydrogel contact lenses of 318 participants in the Contact Lens and Dry Eye Study (CLADES). Dehydration was determined in two ways; as the difference between nominal and measured (1) water content and (2) refractive index. Multiple regression models were used to examine the relation between dehydration and material characteristics, controlling for tear osmolality. The overall measured and nominal water content values were 52.58 +/- 7.49% and 56.88 +/- 7.81% respectively, while the measured and nominal refractive indices were 1.429 +/- 0.015 and 1.410 +/- 0.017. High water content and ionic hydrogel lens materials were associated with greater dehydration (p < 0.0001 for both) than low water content and non-ionic materials. When dehydration was assessed as the difference in refractive index, only high water content was associated with dehydration (p < 0.0001). High water content and ionic characteristics of hydrogel lens materials are associated with hydrogel lens dehydration, with the former being more strongly associated. Such dehydration changes could in turn lead to important clinical ramifications such as reduced oxygen transmissibility, greater lens adherence and reduced tear exchange.

A planar lens based on the electrowetting of two immiscible liquids

NASA Astrophysics Data System (ADS)

Liu, Chao-Xuan; Park, Jihwan; Choi, Jin-Woo

2008-03-01

This paper reports the development and characterization of a planar liquid lens based on electrowetting. The working concept of electrowetting two immiscible liquids is demonstrated with measurement and characterization of contact angles with regard to externally applied electric voltages. Consequently, a planar liquid lens is designed and implemented based on this competitive electrowetting. A droplet of silicone oil confined in an aqueous solution (1% KCl) works as a liquid lens. Electrowetting then controls the shape of the confined silicone oil and the focal length of the liquid lens varies depending upon an applied dc voltage. A unique feature of this lens design is the double-ring planar electrodes beneath the hydrophobic substrate. While an outer ring electrode provides an initial boundary for the silicone oil droplet, an inner ring works as the actuation electrode for the lens. Further, the planar electrodes, instead of vertical or out-of-plane wall electrodes, facilitate the integration of liquid lenses into microfluidic systems. With the voltage applied in the range of 50-250 V, the confined silicone oil droplet changed its shape and the optical magnification of a 3 mm-diameter liquid lens was clearly demonstrated. Moreover, focal lengths of liquid lenses with diameters of 2 mm, 3 mm and 4 mm were characterized, respectively. The obtained results suggest that a larger lens diameter yields a longer focal length and a wider range of focal length change in response to voltage. The demonstrated liquid lens has a simple structure and is easy to fabricate.

The use of contact lens telescopic systems in low vision rehabilitation.

PubMed

Vincent, Stephen J

2017-06-01

Refracting telescopes are afocal compound optical systems consisting of two lenses that produce an apparent magnification of the retinal image. They are routinely used in visual rehabilitation in the form of monocular or binocular hand held low vision aids, and head or spectacle-mounted devices to improve distance visual acuity, and with slight modifications, to enhance acuity for near and intermediate tasks. Since the advent of ground glass haptic lenses in the 1930's, contact lenses have been employed as a useful refracting element of telescopic systems; primarily as a mobile ocular lens (the eyepiece), that moves with the eye. Telescopes which incorporate a contact lens eyepiece significantly improve the weight, comesis, and field of view compared to traditional spectacle-mounted telescopes, in addition to potential related psycho-social benefits. This review summarises the underlying optics and use of contact lenses to provide telescopic magnification from the era of Descartes, to Dallos, and the present day. The limitations and clinical challenges associated with such devices are discussed, along with the potential future use of reflecting telescopes incorporated within scleral lenses and tactile contact lens systems in low vision rehabilitation. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

The Potential Application and Risks Associated With the Use of Predatory Bacteria as a Bio-control Agent Against Wound Infections

DTIC Science & Technology

2015-10-01

wotlllds examined. L Haired skin: Dermatitis , uleeratin , neub’ophilic (acute), focal. severe, with edema, serocellular exudate, and underlying...H, Taylor HR, Vajpayee RB (2007) Association between cultures of contact lens and corneal scraping in contact lens related microbial keratitis. Arch...aeruginosa infection and inflammation during contact lens wear: a review. Optom Vis Sci 84: 273–278. 29. Zhang J, Wu XY, Yu FS (2005) Inflammatory

Fungal keratitis and contact lenses: an old enemy unrecognized or a new nemesis on the block?

PubMed

Tuli, Sonal S; Iyer, Sandhya A; Driebe, William T

2007-11-01

To review studies of fungal keratitis related to contact lenses and determine whether the recent insurgence is a new phenomenon or an exacerbation of an ongoing trend. A review of the recent literature on contact lens-related fungal ulcers and a comparison to older studies. The incidence of fungal keratitis associated with contact lenses increased from 5% in the 1980s to between 10% and 25% in the 1990s and was noted to be 44% in Florida at the turn of the century. The most recent study from Florida showed that the incidence had increased from 29% in the late 1990s to 52% in the early 2000s, even before the Fusarium keratitis epidemic in 2004 and 2005. This increase mainly represented an increase in the number related to nontherapeutic contact lenses. Contact lens-related fungal keratitis was relatively rare 20 years ago. However, the incidence has progressively increased since then. Contact lens-related fungal ulcers had become more common even before the recent Fusarium keratitis epidemic. This change may be related to changing contact lens care habits and younger patients being fitted with contact lenses.

Microelectrofluidic lens for variable curvature

NASA Astrophysics Data System (ADS)

Chang, Jong-hyeon; Lee, Eunsung; Jung, Kyu-Dong; Lee, Seungwan; Choi, Minseog; Kim, Woonbae

2012-10-01

This paper presents a tunable liquid lens based on microelectrofluidic technology which integrates electrowetting and microfluidics. In the novel microelectrofluidic lens (MEFL), electrowetting in the hydrophobic surface channel induces the Laplace pressure difference between two fluidic interfaces on the lens aperture and the surface channel. Then, the pressure difference makes the lens curvature tunable. The previous electrowetting lens in which the contact angle changes at the side wall has a certain limitation of the curvature variation because of the contact angle saturation. Although the contact angle saturation also appears in the surface channel of the MEFL, the low surface channel increases the Laplace pressure and it makes the MEFL to have full variation of the optical power possible. The magnitude of the applied voltage determines the lens curvature in the analog mode MEFL as well as the electrowetting lens. Digital operation is also possible when the control electrodes of the MEFL are patterned to have an array. It is expected that the proposed MEFL is able to be widely used because of its full variation of the optical power without the use of oil and digital operation with fast response.

Risk factors for contact lens bacterial contamination during continuous wear.

PubMed

Szczotka-Flynn, Loretta B; Bajaksouzian, Saralee; Jacobs, Michael R; Rimm, Alfred

2009-11-01

Microbial contamination of contact lenses is associated with corneal infection and inflammation. This study determined the microbiological, clinical, and demographic factors that are associated with bacterial contamination of a silicone hydrogel contact lens when worn for continuous wear (CW). Two hundred five healthy subjects were enrolled in the Longitudinal Analysis of Silicone Hydrogel Contact Lens Study and were fitted with lotrafilcon A lenses for monthly CW and followed for 1 year. Lenses were aseptically removed after 1 week and 4 months of wear and cultured using an agar sandwich technique. Lids and conjunctiva were routinely cultured at baseline and after 1 week and 4 months of CW. Lenses and ocular sites were considered to have substantial microbial bioburden when they harbored pathogenic organisms or high levels of commensal organisms. Univariate and multivariate logistic regression analyses were conducted to examine whether substantial conjunctival or lid bioburden, subject demographics, lens-wearing history, symptoms, and biomicroscopic signs were associated with lens bioburden. About one third (32.4%) of subjects had substantial bacterial bioburden in either eye across multiple visits. Over half (53.2%) and about one tenth (11.7%) of subjects had substantial lid and conjunctival bioburden, respectively, and 11.2% discontinued because of discomfort. The adjusted odds ratios (and 95% confidence intervals) for presence of substantial lens bioburden were 2.49 (1.17-5.30), 4.24 (1.45-12.40), and 4.11 (1.17-14.46) for substantial lid bioburden, substantial conjunctival bioburden, and lens discomfort, respectively. Bacterial contamination of silicone hydrogel contact lenses is common during CW. Substantial lens bioburden is associated with discomfort precluding successful CW. The presence of substantial lid and conjunctival bioburden is associated with a 2.5-fold and more than fourfold greater risk of substantial lens bioburden and is likely the major route of contamination.

Peripheral optics with bifocal soft and corneal reshaping contact lenses.

PubMed

Ticak, Anita; Walline, Jeffrey J

2013-01-01

To determine whether bifocal soft contact lenses with a distance center design provide myopic defocus to the peripheral retina similar to corneal reshaping contact lenses. Myopic subjects underwent five cycloplegic autorefraction readings centrally and at 10, 20, and 30 degrees temporally, nasally, superiorly, and inferiorly while wearing Proclear Multifocal "D" contact lenses with a +2.00-diopter add power (CooperVision, Fairport, NY) and after wearing Corneal Refractive Therapy (Paragon Vision Sciences, Mesa, AZ) contact lenses for 2 weeks. Fourteen subjects completed the study. Nine (64%) were female, and 12 (86%) were white. The average (± SD) spherical equivalent noncycloplegic manifest refraction for the right eye was -2.84 ± 1.29 diopters. The average logMAR best-corrected, binocular, high-contrast visual acuity was -0.17 ± 0.15 while wearing the bifocal soft contact lenses and -0.09 ± 0.16 after corneal reshaping contact lens wear (analysis of variance, p = 0.27). The orthokeratology contact lens yielded a more myopic peripheral optical profile than the soft bifocal contact lens at 20 and 30 degrees eccentricity (except inferior at 20 degrees); the two modalities were similar at 10 degrees eccentricity. Our data suggest that the two modalities are dissimilar despite the statistical similarities. The corneal reshaping contact lens shows an increase in relative peripheral myopic refraction, a pattern achieved by other studies, but the bifocal lens does not exhibit such a pattern. The low statistical power of the study could be a reason for lack of providing statistical difference in other positions of gaze, but the graphical representation of the data shows a marked difference in the peripheral optical profile between the two modalities. More sophisticated methods of measuring the peripheral optical profile may be necessary to accurately compare the two modalities and to determine the true optical effect of the bifocal soft contact lens on the peripheral retina.

Animal models to investigate fungal biofilm formation.

PubMed

Chandra, Jyotsna; Pearlman, Eric; Ghannoum, Mahmoud A

2014-01-01

Microbial biofilms play an essential role in several infectious diseases and are defined as extensive communities of sessile organisms irreversibly associated with a surface, encased within a polysaccharide-rich extracellular matrix (ECM), and exhibiting enhanced resistance to antimicrobial drugs. Forming a biofilm provides the microbes protection from environmental stresses due to contaminants, nutritional depletion, or imbalances, but is dangerous to human health due to their inherent robustness and elevated resistance.The use of indwelling medical devices (e.g., central venous catheters, CVCs) in current therapeutic practice is associated with 80-90 % of hospital-acquired bloodstream and deep tissue infections. Most cases of catheter-related bloodstream infections (CRBSIs) involve colonization of microorganisms on catheter surfaces where they form a biofilm. Additionally, Fusarium solani and F. oxysporum were the causative organisms of the 2005/2006 outbreak of contact lens-associated fungal keratitis in the United States, Europe, the UK, and Singapore, and these infections involved formation of biofilms on contact lens. Fungal biofilm formation is studied using a number of techniques, involving the use of a wide variety of substrates and growth conditions. In vitro techniques involving the use of confocal scanning laser/scanning electron microscopy, metabolic activity assay, dry weight measurements, and antifungal susceptibility assays are increasingly used by investigators to quantify and evaluate biofilm morphology. However, there are not many in vivo models used to validate biofilm-associated infections. In this protocol, we describe a clinically relevant rabbit model of C. albicans biofilm-associated catheter infection to evaluate the morphology, topography, and architecture of fungal biofilms. We also describe a murine model of contact lens-associated Fusarium keratitis.Evaluation of the formation of fungal biofilms on catheters in vivo, their analysis using scanning electron microscopy (SEM) and quantitative catheter culture (QCC), and treatment of biofilms using antimicrobial lock therapy can be completed in ~20-25 days using the described methods. The rabbit model has utility in evaluating the efficacy of lock solutions. In addition, the murine model of contact lens-associated Fusarium keratitis enables characterizing/comparing the formation of Fusarium biofilms on contact lenses in vitro and determining their role in vivo.

Corneal Biomechanical Changes Following Toric Soft Contact Lens Wear.

PubMed

Radaie-Moghadam, Somayeh; Hashemi, Hassan; Jafarzadehpur, Ebrahim; Yekta, Abbas Ali; Khabazkhoob, Mehdi

2016-01-01

To determine the effect of using toric soft contact lenses on corneal biomechanical properties. We enrolled 33 healthy patients with mean age of 23.18 ± 4.06 and minimal cylinder power of 1 D (-1.98 ± 0.808 SD) and negative history of contact lens use; keratoconic patients were excluded from the study. Toric soft contact lenses (BIOFINITY, Comfilcon A, Coopervision, Southampton, UK) were fitted in all participants. The Ocular Response Analyzer (Reichert Ophthalmic Instruments, Depew, New York, USA) was used to measure corneal hysteresis (CH), corneal resistance factor (CRF), and the Pentacam HR (Oculus, Inc., Lynnwood, WA, USA) was used to measure central corneal thickness (CCT) and mean keratometry (K mean) before and one week, one month, and three months after using the toric soft contact lenses. CH and CRF were decreased significantly one month after using the contact lens; mean CH decreased from 9.99 ± 1.44 to 9.59 ± 1.54 mmHg, and mean CRF decreased from 9.96 ± 1.71 to 9.63 ± 1.73 mmHg (P = 0.013 and P = 0.017, respectively). Mean CCT and K mean did not show a significant change during the period of toric soft contact lens use. CH and CRF decreased significantly one month after fitting toric soft contact lenses while CCT and Kmean did not change significantly. Corneal biomechanical parameters may alter with toric soft contact lens use and such changes may have implications with long-term use such lenses.

Bilateral Acanthamoeba ulcer in a user of disposable soft contact lenses: a tragic incident or a consequence of the aggressive policy of soft contact lens trading?

PubMed

Sousa, Sidney Júlio de Faria E; Dias, Vanderson Glerian; Marcomini, Luís Antonio Gorla

2008-01-01

This is the report of a case of bilateral Acanthamoeba keratitis in a 19-year-old woman who bought a pair of disposable soft contact lenses in a boutique. She wore this same pair of lenses for 3 months daily without the appropriate care. This led to bilateral corneal transplantation with cataract extraction and also trabeculectomy in the right eye. When last seen, both grafts were crystal clear but the visual acuities were far from satisfactory. She also had bilateral secondary glaucoma, barely controlled by topical medication. Actually, the physical features and the wearing time characteristics of the disposable soft contact lenses created unprecedented difficulties to the medical surveillance of their wearers. Without the right assistance they tend to become careless regarding routine cleaning. They also feel free to buy less expensive lenses, to use saline instead of lens solutions, to violate the limits of wearing time and to extend the use over the sleeping period. Additionally, the aggressive marketing and the wide distribution of these lenses increase the chances that economically or educationally unprepared people will acquire them. The question that remains is: Is the present case an accidental event or an example of what is likely to happen in the future if the indiscriminate selling of disposable soft contact lenses continues to evolve?

Contact lens induced papillary conjunctivitis with silicone hydrogel lenses.

PubMed

Sorbara, L; Jones, L; Williams-Lyn, D

2009-04-01

To describe the refitting of a soft lens wearer into a silicone hydrogel lens due to neovascularization. This change, in turn, caused contact lens induced papillary conjunctivitis (CLPC) and a further refitting was necessary. The patient was refit into a high Dk surface treated silicone hydrogel with a high modulus value. A second refitting was undertaken into a lower Dk silicone hydrogel contact lens with a lower modulus value which had no surface treatment but incorporated an internal wetting agent. A high Dk/t lens was used to resolve existing neovascularization and chronic hyperaemia. Subsequently, CLPC response occurred, possibly due to a combination of factors, resulting in irritation of the palpebral conjunctiva. This resulted in temporary lens discontinuation. A second silicone hydrogel lens was fit, along with the use of a non-preserved care system, which led to improvement and eventual resolution of the condition. High Dk silicone hydrogel lenses have shown excellent efficacy in resolving hypoxic complications such as neovascularization and hyperaemia. However, attention needs to be paid to their potential effect on the upper tarsal plate. More than one silicone hydrogel lens may be needed to help resolve these issues.

Randomized Crossover Trial of Silicone Hydrogel Presbyopic Contact Lenses.

PubMed

Sivardeen, Ahmed; Laughton, Deborah; Wolffsohn, James S

2016-02-01

To assess the performance of four commercially available silicone hydrogel multifocal monthly contact lens designs against monovision. A double-masked randomized crossover trial of Air Optix Aqua multifocal, PureVision 2 for Presbyopia, Acuvue OASYS for Presbyopia, Biofinity multifocal, and monovision with Biofinity contact lenses was conducted on 35 presbyopes (54.3 ± 6.2 years). After 4 weeks of wear, visual performance was quantified by high- and low-contrast visual acuity under photopic and mesopic conditions, reading speed, defocus curves, stereopsis, halometry, aberrometry, Near Activity Visual Questionnaire rating, and subjective quality of vision scoring. Bulbar, limbal, and palpebral hyperemia and corneal staining were graded to monitor the impact of each contact lens on ocular physiology. High-contrast photopic visual acuity (p = 0.102), reading speed (F = 1.082, p = 0.368), and aberrometry (F = 0.855, p = 0.493) were not significantly different between presbyopic lens options. Defocus curve profiles (p < 0.001), stereopsis (p < 0.001), halometry (F = 4.101, p = 0.004), Near Activity Visual Questionnaire (F = 3.730, p = 0.007), quality of vision (p = 0.002), bulbar hyperemia (p = 0.020), and palpebral hyperemia (p = 0.012) differed significantly between lens types, with the Biofinity multifocal lens design principal (center-distance lens was fitted to the dominant eye and a center-near lens to the nondominant eye) typically outperforming the other lenses. Although ocular aberration variation between individuals largely masks the differences in optics between current multifocal contact lens designs, certain design strategies can outperform monovision, even in early presbyopes.

Characterization of Soft Contact Lens Edge Fitting during Daily Wear Using Ultrahigh-Resolution Optical Coherence Tomography.

PubMed

Cui, Lele; Chen, Sisi; Zhou, Weihe; Sheng, Kaixuan; Zhang, Lei; Shen, Meixiao; Li, Ming

2018-01-01

To determine conjunctival overlap over the edge of soft contact lens and to visualize the peripheral postlens tear film (PoLTF) underneath soft contact lenses using ultrahigh-resolution optical coherence tomography (UHR-OCT). Twenty participants (4 males and 16 females, 23.0 ± 3.7 years) were fitted with two different types of soft contact lenses randomly. The limbus with lens was imaged with the UHR-OCT at the horizontal meridian every two hours up to 6 hours during lens wear. The conjunctival overlap was ranked as the percentage of the edge covered by the conjunctiva. The frequency of occurrence for visualized peripheral PoLTF was determined. The average conjunctival overlaps at insertion were 49% and 73% for galyfilcon A and balafilcon A lenses and increased significantly to 84% and 90% by 6 hours of lens wear ( P < 0.001). Lenses with rounded edges had more conjunctival overlap than the lenses with angled edges ( P =0.014). There were significant decreases for PoLTF on the conjunctiva ( P =0.014) and peripheral cornea ( P =0.004) over the study period compared to insertion. The percentage of subjects with PoLTF on the conjunctiva (32.5%) and peripheral cornea (36%) were greater in subjects wearing balafilcon A lenses ( P =0.017). Increased conjunctival overlap over the lens edges and reduced PoLTF underneath the peripheral region of soft contact lenses were shown during lens daily wear. The lens edge configuration may play a role in conjunctival response and peripheral PoLTF.

IgE antibody on worn highly oxygen-permeable silicone hydrogel contact lenses from patients with contact lens-induced papillary conjunctivitis (CLPC).

PubMed

Zhao, Zhenjun; Fu, Han; Skotnitsky, Cheryl C; Sankaridurg, Padmaja R; Willcox, Mark D P

2008-03-01

To investigate whether the level of IgE is increased in the eyes of patients during general contact lens-induced papillary conjunctivitis (CLPC) events, which involve enlarged papillae across the entire palpebral conjunctiva, or local CLPC events, in which papillae are confined to one or two parts of the area. Worn contact lenses were collected and soaked in phosphate-buffered saline. The levels of eluted IgE and IgE retained on contact lenses were detected by enzyme-linked immunosorbent assay. IgE was detected in 6 of 12 cases of general CLPC, 8 of 21 cases of local CLPC, and none of 14 control contact lenses. The average level of eluted IgE was 0.54 +/- 1.06 IU/contact lens, 0.28 +/- 0.54 IU/contact lens, and 0.04 +/- 0.06 IU/contact lens for general CLPC, local CLPC, and the control group, respectively. The incidences of positive IgE were significantly higher in patients with CLPC (general and local) than in control subjects, but no statistical difference was found between general and local CLPC. Generally higher amounts of retained IgE were detected on contact lenses that had increased levels of eluted IgE. Contact lenses that were collected before or after a CLPC event did not show increased levels of IgE. The level of IgE is increased in the eyes of some patients during an acute event of CLPC. The similar incidence of IgE-positive cases and levels of IgE from general and local CLPC contact lenses suggest that the conditions may share similar causal pathways.

Comparison of ocular comfort, vision, and SICS during silicone hydrogel contact lens daily wear.

PubMed

Diec, Jennie; Evans, Victoria E; Tilia, Daniel; Naduvilath, Thomas; Holden, Brien A; Lazon de la Jara, Percy

2012-01-01

The aim of this study was to investigate the relationship between solution-induced corneal staining (SICS) and silicone hydrogel contact lens comfort and vision. A retrospective analysis of a series of open-label studies were conducted with 24 groups of approximately 40 participants, each wearing 1 of 6 silicone hydrogel contact lenses with 1 of 4 lens care products bilaterally for 3 months of daily wear. The presence of SICS and subjective ocular ratings were collected at 2 weeks and at 1 and 3 months. A total of 1,051 participants were enrolled. The participants with SICS rated significantly less favorably than did the participants without SICS for comfort during the day (7.9±1.7 vs. 8.5±1.4, P=0.03), comfort at the end of the day (6.6±2.1 vs. 7.4±1.9, P=0.03), overall dryness (7.4±1.9 vs. 8.0±1.7, P=0.04), dryness at the end of the day (6.7±2.2 vs. 7.5±2.1, P=0.01), feelings of burning and stinging (8.5±2.0 vs. 8.9±1.8, P=0.02), and overall vision (8.2±1.6 vs. 8.7±1.3, P<0.001). The participants with SICS had lower subjective comfort and vision compared with those who did not experience SICS.

Comparing goblet cell densities in patients wearing disposable hydrogel contact lenses versus silicone hydrogel contact lenses in an extended-wear modality.

PubMed

Lievens, Christopher W; Connor, Charles G; Murphy, Heather

2003-10-01

The current study evaluates the response of the ocular surface to extended contact lens wear by comparing a new silicone hydrogel lens to an ACUVUE 2 lens. Twenty subjects with an average age of 28 years were randomly assigned to a fitting with ACUVUE 2 or PureVision lenses. Ocular surface assessment by impression cytology was performed at baseline and for the 6 months after initiation of lens wear. Although goblet cell density significantly increased with wear time, no statistically significant difference was observed between the contact lens groups. The average baseline goblet cell percentages were as follows: ACUVUE 2 group, 1.44; PureVision group, 1.11. The 6-month averages were as follows: ACUVUE 2 group, 3.16; PureVision group, 2.22. It appears that silicone hydrogel lenses may be slightly less irritating to the ocular surface than lenses not containing silicone. This could be a promising indicator for successful 30-day continuous wear.

Staphylococcus aureus causes acute inflammatory episodes in the cornea during contact lens wear.

PubMed

Wu, P Z; Thakur, A; Stapleton, F; Willcox, M D

2000-06-01

The aim of this investigation was to determine the ability of Staphylococcus aureus to cause keratitis during contact lens wear in the rabbit. Rabbits were fitted with hydrogel lenses and wore them on an extended wear schedule for 7 weeks. At the end of each week of wear, one drop of S. aureus was added to the eyes, and the eyes were monitored using slit lamp bio-microscopy, with subsequent microbial and histological studies of the cornea. In the presence of S. aureus, keratitis occurred after 3 weeks of lens wear, a condition that was characterized by diffuse infiltration of the peripheral cornea and limbal redness. In the absence of bacteria, there was no infiltration until week 6. Contact lens wear also prolonged the retention of bacteria in the eye. Extended contact lens wear and S. aureus caused non-ulcerative keratitis in a rabbit model, and disturbances in the ability of the eye to remove bacteria.

Experience with the lathe cut Bausch & Lomb Soflens: Part II--Power and optics study.

PubMed

Weissman, B A; Levinson, A

1978-04-01

Ten familiar spin cast and ten lathe cut Bausch & Lomb SOFLENS contact lenses were measured as to their power on a lensometer and on an eye. Both quality of the optics and quantitative measurements were considered. Lens flexure and the presence of a fluid lens between the posterior surface of the contact lens and the anterior cornea is indicated for both lenses to explain differences between power of the lens in air and on the eye. The spin cast lens design appears to create a quantitatively larger fluid lens, and one which will add positive optical power to the lens/eye system. Either from this and/or additional factors, the lathe cut lens appears to give improved optical performance both in air and on the eye.

Evaluation of the Tear Function Tests and the Ocular Surface in First-Time Users of Silicone Hydrogel Contact Lenses.

PubMed

Yildiz Tasci, Yelda; Gürdal, Canan; Sarac, Ozge; Onusever, Aykut

2017-07-01

To evaluate the effects of three different silicone hydrogel contact lenses (SHCL), (balafilcon A, senofilcon A, and comfilcon A) on tear function tests, corneal thickness, and ocular surface cytology in first time contact lens users. In this prospective study, 120 eyes of 60 subjects were evaluated. Balafilcon A users were designated as group 1, senofilcon A users as group 2, and comfilcon A users as group 3. In all cases, before and after 6 months of contact lens wear, ocular surface disease index score (OSDI), tear breakup time (TBUT), Schirmer 1 test, central corneal thickness (CCT), central corneal epithelium thickness (CCET), and conjunctival impression cytology samples were evaluated. In group 1, 40 eyes of the 20 patients, in group 2, 40 eyes of the 20 patients, and in group 3, 40 eyes of the 20 patients were evaluated. The mean OSDI scores did not differ between the three groups after contact lens wear (p > 0.05). In group 1 and group 2, significant decrease was found in the mean TBUT 6 months after contact lens wear (p = 0.04, p < 0.001, respectively). In group 3, after 6 months of contact lens wear, the mean Schirmer 1 tear test was decreased significantly (p = 0.021). In all 3 groups, no significant change was observed in the mean CCT and CCET after contact lens wear (p > 0.05). After 6 months, the morphological changes in temporal and superior conjunctival epithelial cells were found to be significant in all groups (p < 0.001). Six months after SHCL wear, marked morphological changes occurred in the conjunctival epithelium. Tear function tests were also affected, while corneal thickness did not show any significant difference.

Cytotoxic and inflammatory effects of contact lens solutions on human corneal epithelial cells in vitro.

PubMed

Oh, Sarah; McCanna, David J; Subbaraman, Lakshman N; Jones, Lyndon W

2018-06-01

To ascertain the effect that four contact lens (CL) multipurpose solutions (MPS) have on the viability and release of pro-inflammatory cytokines from human corneal epithelial cells (HCEC). HCEC were exposed to four different MPS at various concentrations for 18 hours. The cells were also exposed to phosphate buffer, borate buffer, and PHMB. The cell viability was evaluated using the alamarBlue assay. The release of pro-inflammatory cytokines was measured using a Multiplex electrochemiluminescent assay. MPS-A, MPS-B and MPS-C all reduced cell metabolic activity p < 0.05 from control with MPS-A showing the greatest cytotoxic effect (maximum reduction, 90.6%). In contrast, MPS-D showed no significant reductions in cytotoxicity except at the highest concentration tested (19% reduction at 20% MPS concentration). Of the four cytokines evaluated MPS-C showed a substantial increase in the release of IL-1β, IL-6, IL-8, and TNF-α at higher concentrations when compared to control p < 0.05. At the 20% concentration of MPS-A and MPS-B the release of IL-1 β increased p < 0.05 but the release of IL-6, IL-8, and TNF-α decreased. MPS-D did not cause a change in the release of cytokines IL-1β, IL-6, IL-8 and TNF-α p > 0.05. Exposing the cells to borate buffer and PHMB caused an increase in the release of TNF-α p < 0.05. This investigation demonstrates that at different concentration levels, several of the MPS tested showed a decrease in viability and an increase in the release of inflammatory cytokines from HCEC. The borate buffer component as well as PHMB appears to contribute to this pro-inflammatory reaction. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Comparison of contact lens and intraocular lens correction of monocular aphakia during infancy: a randomized clinical trial of HOTV optotype acuity at age 4.5 years and clinical findings at age 5 years.

PubMed

Lambert, Scott R; Lynn, Michael J; Hartmann, E Eugenie; DuBois, Lindreth; Drews-Botsch, Carolyn; Freedman, Sharon F; Plager, David A; Buckley, Edward G; Wilson, M Edward

2014-06-01

The efficacy and safety of primary intraocular lens (IOL) implantation during early infancy is unknown. To compare the visual outcomes of patients optically corrected with contact lenses vs IOLs following unilateral cataract surgery during early infancy. The Infant Aphakia Treatment Study is a randomized clinical trial with 5 years of follow-up that involved 114 infants with unilateral congenital cataracts at 12 sites. A traveling examiner assessed visual acuity at age 4.5 years. Cataract surgery with or without primary IOL implantation. Contact lenses were used to correct aphakia in patients who did not receive IOLs. Treatment was determined through random assignment. HOTV optotype visual acuity at 4.5 years of age. The median logMAR visual acuity was not significantly different between the treated eyes in the 2 treatment groups (both, 0.90 [20/159]; P = .54). About 50% of treated eyes in both groups had visual acuity less than or equal to 20/200. Significantly more patients in the IOL group had at least 1 adverse event after cataract surgery (contact lens, 56%; IOL, 81%; P = .02). The most common adverse events in the IOL group were lens reproliferation into the visual axis, pupillary membranes, and corectopia. Glaucoma/glaucoma suspect occurred in 35% of treated eyes in the contact lens group vs 28% of eyes in the IOL group (P = .55). Since the initial cataract surgery, significantly more patients in the IOL group have had at least 1 additional intraocular surgery (contact lens, 21%; IOL, 72%; P < .001). There was no significant difference between the median visual acuity of operated eyes in children who underwent primary IOL implantation and those left aphakic. However, there were significantly more adverse events and additional intraoperative procedures in the IOL group. When operating on an infant younger than 7 months of age with a unilateral cataract, we recommend leaving the eye aphakic and focusing the eye with a contact lens. Primary IOL implantation should be reserved for those infants where, in the opinion of the surgeon, the cost and handling of a contact lens would be so burdensome as to result in significant periods of uncorrected aphakia. clinicaltrials.gov Identifier: NCT00212134

Bilateral corneal erosion due to retail purchase of unfitted prescription contact lenses: a case report.

PubMed

Tseng, Santos Shan-Yu; Yang, Winston Wen-Ching; Hsiao, John Ching-Jen

2008-12-01

We report a case demonstrating the importance of trial fitting before the dispensing of prescription contact lenses. The patient was an 18-year-old computer-using experienced hydrogel lens wearer who ran out of contact lens supply. The patient purchased a brand new box of daily disposable lenses from a retail store having known his back vertex power. No trial fitting of the lenses was performed at the point of sale. After a day of wear of the lenses with significant computer use, the patient removed them and went to bed, but the next morning, presented on an emergency basis with severe pain and blurry vision in both eyes. Slit lamp examination showed significant bilateral corneal erosions that were treated with prophylactic antibiotics, steroids, and lubricants. A bandage contact lens was further given to his right eye. The characteristics of the daily disposable lenses and his computer overuse were viewed as contributing factors to the complication. The dispensing and wear of prescription contact lenses without a proper selection and fit led to bilateral corneal erosions in this patient. Though our case occurred in Taiwan, a jurisdiction where prescription contact lens sale is not regulated, the authors note that such a scenario could occur in jurisdictions where contact lens sale is regulated if, after confirmation of back vertex power, no effort is made to ensure that a purchased lens is safe or appropriate for a patient, such as when lenses are purchased through internet suppliers or in certain commercial retail settings.

Publication analysis of the contact lens field: what are the current topics of interest?

PubMed

Cardona, Genís; Sanz, Joan P

2015-01-01

To determine the main current research interests of scientists working in the contact lens field. All articles published in the 2011 issues of all journals included in the Journal Citation Reports subject category Ophthalmology were inspected to expose those papers related to the contact lens field. Information regarding source journal was obtained and authorship details were recorded to determine the top most prolific authors, institutions and countries. A comprehensive list of key words was compiled to generate a two-dimensional term map in which the frequency of occurrence of a particular term is defined by label size and the distance between two terms is an indication of the relatedness of these terms, based on their co-occurrences within groups of key words. Clusters of related terms were also identified. Visual examination of all articles uncovered a total of 156 papers, published in 28 different journals. Contact Lens & Anterior Eye, Eye & Contact Lens and Optometry and Vision Science had 27 articles each. The most prolific authors and institutions revealed the predominance of countries with long research tradition in the contact lens field. Ten different word clusters or areas of interest were identified, including both traditional, yet unresolved issues (e.g., comfort or dry eye), and the latest research efforts (e.g., myopia control). These findings, which revealed contact lenses to be a fertile area of research, may be of relevance to new researchers as well as to those interested in exploring the latest research trends in this scientific discipline. Copyright © 2013 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Power Profiles and In Vitro Optical Quality of Scleral Contact Lenses: Effect of the Aperture and Power.

PubMed

Domínguez-Vicent, Alberto; Esteve-Taboada, Jose Juan; Recchioni, Alberto; Brautaset, Rune

2018-05-01

To assess the power profile and in vitro optical quality of scleral contact lenses with different powers as a function of the optical aperture. The mini and semiscleral contact lenses (Procornea) were measured for five powers per design. The NIMO TR-1504 (Lambda-X) was used to assess the power profile and Zernike coefficients of each contact lens. Ten measurements per lens were taken at 3- and 6-mm apertures. Furthermore, the optical quality of each lens was described in Zernike coefficients, modulation transfer function, and point spread function (PSF). A convolution of each lens PSF with an eye-chart image was also computed. The optical power fluctuated less than 0.5 diopters (D) along the optical zone of each lens. However, the optical power obtained for some lenses did not match with its corresponding nominal one, the maximum difference being 0.5 D. In optical quality, small differences were obtained among all lenses within the same design. Although significant differences were obtained among lenses (P<0.05), these showed small impact in the image quality of each convolution. Insignificant power fluctuations were obtained along the optical zone measured for each scleral lens. Additionally, the optical quality of both lenses has showed to be independent of the lens power within the same aperture.

Peripheral corneal infiltrates associated with contact lens wear.

PubMed Central

Donshik, P C; Suchecki, J K; Ehlers, W H

1995-01-01

PURPOSE: A retrospective study was performed to review the clinical characteristics of peripheral corneal infiltrates in contact lens wearers. METHODS: The charts of all contact lens patients with peripheral corneal infiltrates 1.5 mm or less in size who presented to the office from 1987 to 1994 were reviewed. RESULTS: The epidemiological and clinical characteristics of peripheral corneal infiltrates associated with contact lens wear were reviewed in 52 patients (64 infiltrates). Forty-four patients presented with a single infiltrate, while the remaining 8 patients had multiple infiltrates. While there was no predilection for a specific quadrant of the cornea, when a subgroup of patients who wore extended wear lenses was analyzed, 19 of the 40 infiltrates were located in the superior quadrant. Forty percent of the patients were wearing disposable extended wear contact lenses, 21% were wearing conventional extended wear lenses, 33% were wearing conventional or frequent replacement/disposable daily wear contact lenses and 6% were wearing rigid gas permeable lenses. The majority of patients had minimal conjunctival inflammation, an anterior stromal cellular reaction and minimal anterior chamber activity. A subgroup of 16 patients had corneal cultures of their infiltrates. In this group, 8 of the 16 had positive cultures. All patients had a resolution of the infiltrates without complications and the majority were refitted to daily wear soft or rigid contact lenses. CONCLUSION: Peripheral corneal infiltrates in contact lens wearers appears to be more common in patients wearing extended wear soft contact lenses. While often considered "sterile" in the literature, a significant number have been shown to be culture-positive. The organisms that have been associated with peripheral infiltrates appear to be less "pathogenic" than those that have been reported to be associated with central corneal ulcer. However, it is probably advisable that patients with peripheral corneal ulcers secondary to contact lens wear should be initially treated with topical antibiotics. PMID:8719670

Character of Mg(ClO4)2 Brines Under Mars Regolith Conditions

NASA Technical Reports Server (NTRS)

Zent, A. P.; Sizemore, H. G.; Rempel, A. W.

2013-01-01

Elsewhere, we report on our investigation of the initiation and growth of ice lenses under Mars like conditions. In that work, we assume that the soil-water-ice system is gas and solute free. We conclude that initiation of lens initiation - the unloading of particle-particle contacts by thermomolecular forces at a given soil horizon - may be a common process in the shallow Martian regolith, and that the dominant property controlling the rate of lens growth is the freezing point depression (Delta-T(sub f)) associated with the interfacial forces of the soil. Lens growth is thus favored in clay-sized soils over silt soils due to the greater Delta-T(sub f), but segregated ice was observed at the Phoenix site, where soils were predominantly siltsized.. Perchlorate salts were also observed at the Phoenix site, and will strongly affect some of the properties associated with potential ice lens growth, over and above increases to Delta-T(sub f),. Here, we investigate the nature of Mg(ClO4)2 brines under Mars-like conditions, with particular emphasis on those aspects that might influence the in situ segregation of residual liquids during phase change, potentially leading to the formation of subsurface excess ice. We also discuss cyclic variations in the water activity (a(sub w)) that might affect the habitability of solutions in the shallow regolith.

[Ocular and visual alterations in computer workers contact lens wearers: scoping review].

PubMed

Tauste Francés, Ana; Ronda-Pérez, Elena; Seguí Crespo, María del Mar

2014-01-01

The high number of computer workers wearing contact lenses raises the question whether the sum of these two risk factors for eye health may cause a worsening of Computer Vision Syndrome. The aim of this review is to synthesize the knowledge about ocular and visual alterations related with computer use in contact lens wearers. International review of scientific papers (2003-2013) in Spanish and English, using Scoping Review method, in Medline through PubMed and in Scopus. The initial search provided 114 references, after applying inclusion/exclusion criteria six of them were included. All of them reveal that symptoms when using computer are more prevalent in contact lens wearers, with values of symptoms presentation prevalence ranging from 95.0% to 16.9% in wearers and from 57.5% to 9.9% in non-wearers, and four times more likely to develop dry eye [OR: 4.07 (95% CI: 3.52 to 4.71)]. Computer workers suffer more ocular and visual disturbances if they also are contact lens users, but studies are few and non conclusive. Likewise, further research regarding contact lens type and their conditions of use, both in symptoms and tear quality and ocular surface are needed. Silicone hydrogel lenses are associated with more comfort.

The effects of two different types of bandage contact lenses on the healthy canine eye.

PubMed

Braus, Barbara Katharina; Riedler, Daniela; Tichy, Alexander; Spergser, Joachim; Schwendenwein, Ilse

2018-02-06

To compare two types of bandage contact lenses on the healthy canine eye. Six healthy Beagles. Two different types of bandage contact lenses (single sized human silicone contact lens 'PureVision 2' (Bausch & Lomb Incorporated, Rochester, NY, USA) and specially designed veterinary hydrogel contact lens 'AcriVet Pat D' (Bausch & Lomb Incorporated) were placed in 12 eyes of healthy Beagle dogs. Retention times and the effects of the lenses regarding irritation of the eye, changes in tear production, impact of contact lenses on tonometric readings, and cytologic and microbiological alterations of the canine eye were investigated. Mean retention times for veterinary hydrogel lenses with special dimensions were significantly shorter (2 days) than for one size human silicon lenses (8.8 days). Irritation scores were overall low for both types of lenses apart from one human lens causing severe irritation and keratoconjunctivitis as a sequel to folding and displacement. Tear production remained stable in human contact lenses. Intraocular pressure readings with a contact lens in place were only slightly altered; the most accurate readings were obtained through a human lens with an applanation tonometer. Cytology revealed a slight, nonsignificant increase in neutrophilic granulocytes with both types of lenses; the microflora did not change significantly. Human silicone lenses have significantly longer retention times and are less expensive than veterinary hydrogel lenses. In regard to irritation, bacterial growth and inflammation, both types of lenses can be recommended for use in canine eyes. © 2018 American College of Veterinary Ophthalmologists.

Kinetics of Competitive Adsorption between Lysozyme and Lactoferrin on Silicone Hydrogel Contact Lenses and the Effect on Lysozyme Activity.

PubMed

Hall, Brad; Jones, Lyndon; Forrest, James A

2015-05-01

To determine the effect of competitive adsorption between lysozyme and lactoferrin on silicone hydrogel contact lenses and the effect on lysozyme activity. Three commercially available silicone hydrogel contact lens materials (senofilcon A, lotrafilcon B and balafilcon A) were examined, for time points ranging from 10 s to 2 h. Total protein deposition was determined by I(125) radiolabeling of lysozyme and lactoferrin, while the activity of lysozyme was determined by a micrococcal activity assay. Senofilcon A and balafilcon A did not show any relevant competitive adsorption between lysozyme and lactoferrin. Lotrafilcon B showed reduced protein deposition due to competitive adsorption for lactoferrin at all time points and lysozyme after 7.5 min. Co-adsorption of lactoferrin and lysozyme decreased the activity of lysozyme in solution for senofilcon A and lotrafilcon B, but co-adsorption had no effect on the surface activity of lysozyme for all lens types investigated. Competition between lysozyme and lactoferrin is material specific. Co-adsorption of lysozyme and lactoferrin does not affect the activity of surface-bound lysozyme but can reduce the activity of subsequently desorbed lysozyme.

Contamination risk of reusing daily disposable contact lenses.

PubMed

Boost, Maureen; Poon, Kin-Chiu; Cho, Pauline

2011-12-01

This study investigated contamination of saline and daily disposable contact lens (DDCL) stored overnight after use in the original blister pack and the practices of a group of DDCL users. Twenty DDCL wearers placed their lenses after 1 day's use back into the blister pack saline (BPS) and left them overnight before transferring both lens and BPS to a new CL case. The lens and BPS were cultured the following day, and total number of organisms, Staphylococci, and gram negative organisms enumerated. Each subject submitted five pairs of lenses over a 1 month period. Ninety-five percent of subjects had at least one pair of contaminated lenses, and the BPS yielded similar results to the contaminated lenses, with staphylococcal contamination being predominant. Three subjects admitted to not washing their hands before handling their lenses and six to habitual reuse of their lenses with storage in the BPS. There was a higher risk of contamination in male subjects. Reuse of lenses poses an important risk for DDCL users because they are unlikely to have received proper training in cleaning and disinfection of lenses and do not use a lens case or disinfecting solutions. Overnight storage in BPS results in contaminated lenses which if reused increases the infection risk especially with Staphylococci. It is important that practitioners carefully educate their patients in correct use of DDCL and, as cost of lenses is a major factor in willingness to reuse, ensure that DDCL is the most suitable choice when prescribing.

Asymptomatic corneal staining associated with the use of balafilcon silicone-hydrogel contact lenses disinfected with a polyaminopropyl biguanide-preserved care regimen.

PubMed

Jones, Lyndon; MacDougall, Nancy; Sorbara, L Gina

2002-12-01

To compare subjective symptoms and signs in a group of individuals who wear silicone-hydrogel lenses on a daily wear basis while they sequentially used two differing care regimens. Fifty adapted soft-lens wearers were fitted with a silicone-hydrogel lens material (PureVision, Bausch & Lomb). The lenses were worn on a daily wear basis for two consecutive 1-month periods, during which the subjects used either a Polyquad (polyquaternium-1) -based system or a polyaminopropyl biguanide (PHMB) -based system, using a double-masked, randomized, crossover experimental design. Significant levels of relatively asymptomatic corneal staining were observed when subjects used the PHMB-based system, with 37% of subjects demonstrating a level of staining consistent with a classical solution-based toxicity reaction. Only 2% of the subjects exhibited such staining when using the Polyquad-based system. These results were significantly different (p < 0.001). Significant symptoms were not correlated with the degree of staining, with no differences in lens comfort or overall preference being reported between the regimens (p = NS). The only statistically significant difference in symptoms related to minor differences in stinging after lens insertion being reported, with the Polyquad-based system demonstrating less stinging (p < 0.008). Practitioners who fit silicone-hydrogel contact lenses on a daily wear basis should be wary of the potential for certain PHMB-containing multipurpose care systems to invoke corneal staining. Switching to non-PHMB based regimens will eliminate this complication in most instances.

Bacterial Colonization of Disposable Soft Contact Lenses Is Greater during Corneal Infiltrative Events than during Asymptomatic Extended Lens Wear

PubMed Central

Sankaridurg, Padmaja R.; Sharma, Savitri; Willcox, Mark; Naduvilath, Thomas J.; Sweeney, Deborah F.; Holden, Brien A.; Rao, Gullapalli N.

2000-01-01

Microorganisms, especially gram-negative bacteria, are considered to play a role in the etiology of certain corneal infiltrative events (CIEs) observed during soft contact lens wear. This study explored the possibility of microbial colonization of soft contact lenses as a risk factor leading to CIEs. In a clinical trial conducted from March 1993 to January 1996, 330 subjects wore disposable soft contact lenses on a 6-night extended-wear and disposal schedule. During this period, 4,321 lenses (118 during CIEs; 4,203 during asymptomatic lens wear) were recovered aseptically and analyzed for microbial colonization. A greater percentage of lenses were free from microbial colonization during asymptomatic wear than during CIEs (42 versus 23%; P < 0.0001). The incidence of gram-positive bacteria, gram-negative bacteria and fungi was greater during CIEs than during asymptomatic lens wear (P < 0.05). During asymptomatic lens wear, gram-positive bacteria were isolated most frequently and were usually normal external ocular microbiota. Of the gram-positive bacteria, the incidence of Streptococcus pneumoniae was greater during CIE than during asymptomatic wear (7.6 versus 0.6%; P < 0.0001). While gram-negative bacteria were seen in few cases during asymptomatic wear, their incidence during CIE in comparison to asymptomatic wear was substantial and significant (23.7 versus 3.8%; P < 0.0001). Also, the level of colonization was high. Of CIEs, events of microbial keratitis, contact lens acute red eye, and asymptomatic infiltrative keratitis were associated with lens colonization with gram-negative bacteria or S. pneumoniae. Colonization of soft contact lenses with pathogenic bacteria, especially gram-negative bacteria and S. pneumoniae, appears to be a significant risk factor leading to CIE. PMID:11101574

Plasma surface modification of rigid contact lenses decreases bacterial adhesion.

PubMed

Wang, Yingming; Qian, Xuefeng; Zhang, Xiaofeng; Xia, Wei; Zhong, Lei; Sun, Zhengtai; Xia, Jing

2013-11-01

Contact lens safety is an important topic in clinical studies. Corneal infections usually occur because of the use of bacteria-carrying contact lenses. The current study investigated the impact of plasma surface modification on bacterial adherence to rigid contact lenses made of fluorosilicone acrylate materials. Boston XO and XO2 contact lenses were modified using plasma technology (XO-P and XO2-P groups). Untreated lenses were used as controls. Plasma-treated and control lenses were incubated in solutions containing Staphylococcus aureus or Pseudomonas aeruginosa. MTT colorimetry, colony-forming unit counting method, and scanning electron microscopy were used to measure bacterial adhesion. MTT colorimetry measurements showed that the optical density (OD) values of XO-P and XO2-P were significantly lower than those of XO and XO2, respectively, after incubation with S. aureus (P < 0.01). The OD value of XO-P was also much lower than that of XO after incubation with P. aeruginosa (P < 0.01). Colony-forming unit counting revealed that a significantly lower number of bacterial colonies attached to the XO-P versus XO lenses and to the XO2-P versus XO2 lenses incubated with S. aureus (P < 0.01). Fewer bacterial colonies attached to the XO-P versus XO lenses incubated with P. aeruginosa (P < 0.01). Further, scanning electron microscopy suggested different bacterial adhesion morphology on plasma-treated versus control lenses. Plasma surface modification can significantly decrease bacterial adhesion to fluorosilicone acrylate contact lenses. This study provides important evidence of a unique benefit of plasma technology in contact lens surface modification.

The use of contact lenses in low vision rehabilitation: optical and therapeutic applications.

PubMed

Vincent, Stephen J

2017-09-01

Ocular pathology that manifests at an early age has the potential to alter the vision-dependent emmetropisation mechanism, which co-ordinates ocular growth throughout childhood. The disruption of this feedback mechanism in children with congenital or early-onset visual impairment often results in the development of significant ametropia, including high levels of spherical refractive error, astigmatism and anisometropia. This review examines the use of contact lenses as a refractive correction, low vision aid and therapeutic intervention in the rehabilitation of patients with bilateral, irreversible visual loss due to congenital ocular disease. The advantages and disadvantages of the use of contact lenses for increased magnification (telescopes and microscopes) or field expansion (reverse telescopes) are discussed, along with the benefits and practical considerations for the correction of pathological high myopia. The historical and present use of therapeutic tinted contact lenses to reduce photosensitivity and nystagmus in achromatopsia, albinism and aniridia are also presented, including clinical considerations for the contact lens practitioner. In addition to the known optical benefits in comparison to spectacles for high levels of ametropia (an improved field of view for myopes and fewer inherent oblique aberrations), contact lenses may be of significant psycho-social benefit for patients with low vision, due to enhanced cosmesis and reduced conspicuity and potential related effects of improved self-esteem and peer acceptance. The contact lens correction of patients with congenital vision impairment can be challenging for both practitioner and patient but should be considered as a potential optical or therapeutic solution in modern low vision rehabilitation. © 2017 Optometry Australia.

16 CFR 315.4 - Limits on requiring immediate payment.

Code of Federal Regulations, 2010 CFR

2010-01-01

... CONTACT LENS RULE § 315.4 Limits on requiring immediate payment. A prescriber may require payment of fees for an eye examination, fitting, and evaluation before the release of a contact lens prescription, but...

16 CFR 315.4 - Limits on requiring immediate payment.

Code of Federal Regulations, 2011 CFR

2011-01-01

... CONTACT LENS RULE § 315.4 Limits on requiring immediate payment. A prescriber may require payment of fees for an eye examination, fitting, and evaluation before the release of a contact lens prescription, but...

The relationship between morphological changes of lens epithelial cells and intraocular lens optic material.

PubMed

Majima, K

1998-01-01

To examine the morphological changes of lens epithelial cells (LECs) occurring directly beneath and at regions contacting various intraocular lens (IOL) optic materials, human LECs were cultured on human anterior lens capsules and were further incubated upon placing above the cells lens optics made of polymethylmethacrylate, silicone, and soft acrylic material. Observations as to the morphological changes of LECs under phase-contrast microscope and scanning electron microscope were performed on the 14th day of incubation. Gatherings of LECs were observed at regions contacting the soft acrylic material under phase-contrast microscope, and gatherings of LECs were observed accurately at the same regions mentioned above under scanning electron microscope. On the other hand, LECs in contact with two other optic materials did not show morphological changes. The results suggest that LECs attached to and proliferated on not only the anterior lens capsules but also the soft acrylic IOL optics. The model used in this study may be useful in studying the relationship between cellular movement of LECs and IOL optic material.

78 FR 44122 - Agency Information Collection Activities; Submission for OMB Review; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-23

... requirements contained in the Contact Lens Rule. That clearance expires on July 31, 2013 (OMB Control No. 3084... SUPPLEMENTARY INFORMATION section below. FOR FURTHER INFORMATION CONTACT: Requests for additional information or... (Bernstein) and (202) 326-2356 (McGregor). SUPPLEMENTARY INFORMATION: Title: Contact Lens Rule (Rule), 16 CFR...

Scanning Electron Microscopy Findings With Energy-Dispersive X-ray Investigations of Cosmetically Tinted Contact Lenses

PubMed Central

Hotta, Fumika; Imai, Shoji; Miyamoto, Tatsuro; Mitamura-Aizawa, Sayaka; Mitamura, Yoshinori

2015-01-01

Objective: To investigate the surfaces and principal elements of the colorants of cosmetically tinted contact lenses (Cos-CLs). Methods: We analyzed the surfaces and principal elements of the colorants of five commercially available Cos-CLs using scanning electron microscopy with energy-dispersive x-ray analysis. Results: In two Cos-CLs, the anterior and posterior surfaces were smooth, and colorants were found inside the lens. One lens showed colorants located to a depth of 8 to 14 μm from the anterior side of the lens. In the other lens, colorants were found in the most superficial layer on the posterior surface, although a coated layer was observed. The colorants in the other three lenses were deposited on either lens surface. Although a print pattern was uniform in embedded type lenses, uneven patterns were apparent in dot-matrix design lenses. Colorants used in all lenses contained chlorine, iron, and titanium. In the magnified scanning electron microscopy images of a certain lens, chlorine is exuded and spread. Conclusions: Cosmetically tinted contact lenses have a wide variety of lens surfaces and colorants. Colorants may be deposited on the lens surface and consist of an element that has tissue toxicity. PMID:25799458

Fabricating customized hydrogel contact lens

NASA Astrophysics Data System (ADS)

Childs, Andre; Li, Hao; Lewittes, Daniella M.; Dong, Biqin; Liu, Wenzhong; Shu, Xiao; Sun, Cheng; Zhang, Hao F.

2016-10-01

Contact lenses are increasingly used in laboratories for in vivo animal retinal imaging and pre-clinical studies. The lens shapes often need modification to optimally fit corneas of individual test subjects. However, the choices from commercially available contact lenses are rather limited. Here, we report a flexible method to fabricate customized hydrogel contact lenses. We showed that the fabricated hydrogel is highly transparent, with refractive indices ranging from 1.42 to 1.45 in the spectra range from 400 nm to 800 nm. The Young’s modulus (1.47 MPa) and hydrophobicity (with a sessile drop contact angle of 40.5°) have also been characterized experimentally. Retinal imaging using optical coherence tomography in rats wearing our customized contact lenses has the quality comparable to the control case without the contact lens. Our method could significantly reduce the cost and the lead time for fabricating soft contact lenses with customized shapes, and benefit the laboratorial-used contact lenses in pre-clinical studies.

Fabricating customized hydrogel contact lens

PubMed Central

Childs, Andre; Li, Hao; Lewittes, Daniella M.; Dong, Biqin; Liu, Wenzhong; Shu, Xiao; Sun, Cheng; Zhang, Hao F.

2016-01-01

Contact lenses are increasingly used in laboratories for in vivo animal retinal imaging and pre-clinical studies. The lens shapes often need modification to optimally fit corneas of individual test subjects. However, the choices from commercially available contact lenses are rather limited. Here, we report a flexible method to fabricate customized hydrogel contact lenses. We showed that the fabricated hydrogel is highly transparent, with refractive indices ranging from 1.42 to 1.45 in the spectra range from 400 nm to 800 nm. The Young’s modulus (1.47 MPa) and hydrophobicity (with a sessile drop contact angle of 40.5°) have also been characterized experimentally. Retinal imaging using optical coherence tomography in rats wearing our customized contact lenses has the quality comparable to the control case without the contact lens. Our method could significantly reduce the cost and the lead time for fabricating soft contact lenses with customized shapes, and benefit the laboratorial-used contact lenses in pre-clinical studies. PMID:27748361

A Drug-Eluting Contact Lens

PubMed Central

Ciolino, Joseph B.; Hoare, Todd R.; Iwata, Naomi G.; Behlau, Irmgard; Dohlman, Claes H.; Langer, Robert; Kohane, Daniel S.

2014-01-01

Purpose To formulate and characterize a drug-eluting contact lens designed to provide extended, controlled release of a drug. Methods Prototype contact lenses were created by coating PLGA (poly[lactic-co-glycolic acid]) films containing test compounds with pHEMA (poly[hydroxyethyl methacrylate]) by ultraviolet light polymerization. The films, containing encapsulated fluorescein or ciprofloxacin, were characterized by scanning electron microscopy. Release studies were conducted in phosphate-buffered saline at 37°C with continuous shaking. Ciprofloxacin eluted from the contact lens was studied in an antimicrobial assay to verify antimicrobial effectiveness. Results After a brief and minimal initial burst, the prototype contact lenses demonstrated controlled release of the molecules studied, with zero-order release kinetics under infinite sink conditions for over 4 weeks. The rate of drug release was controlled by changing either the ratio of drug to PLGA or the molecular mass of the PLGA used. Both the PLGA and the pHEMA affected release kinetics. Ciprofloxacin released from the contact lenses inhibited ciprofloxacin-sensitive Staphylococcus aureus at all time-points tested. Conclusions A prototype contact lens for sustained drug release consisting of a thin drug-PLGA film coated with pHEMA could be used as a platform for ocular drug delivery with widespread therapeutic applications. PMID:19136709

On-eye breakage and recovery of mini-scleral contact lens without compromise for the ocular surface.

PubMed

Macedo-de-Araújo, Rute J; van der Worp, Eef; González-Méijome, José M

2018-06-01

To report the on-eye breakage of a mini-scleral contact lens in a healthy cornea after being hit by a speeding object, without causing any severe corneal damage. A 24-year-old Caucasian male involved in a clinical study reported the in situ breakage of a mini-scleral contact lens during motorbike maintenance. The patient reported eye redness and irritation that significantly decreased after all the pieces of the lens were recovered from the eye. Ocular examinations within 48 h showed absence of corneal damage other than superficial punctate keratitis inferiorly and no fragments of the lens were found in the conjunctival sac. The patient was wearing a 15.2 mm mini-scleral lens in a high Dk material. The evolution of rigid materials towards higher Dk values has resulted in a decreased hardness and modulus values, so these materials are more elastic when subjected to mechanical stress, which could be a beneficial aspect in absorbing the energy of an impact before breaking in pieces. This case report shows that ScCL could have a protective effect to the corneal surface from the direct impact of a high-speed object. Mechanical material properties, wide supporting area and post-lens tear volume acted as protective factors helping to absorb and distribute the kinetic energy of the impacting object. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Sustained ophthalmic delivery of highly soluble drug using pH-triggered inner layer-embedded contact lens.

PubMed

Zhu, Qiang; Cheng, Hongbo; Huo, Yingnan; Mao, Shirui

2018-06-10

In the present work the feasibility of using inner layer-embedded contact lenses (CLs) to achieve sustained release of highly water soluble drug, betaxolol hydrochloride (BH) on the ocular surface was investigated. Blend film of cellulose acetate and Eudragit S100 was selected as the inner layer, while silicone hydrogel was used as outer layer to construct inner layer-embedded contact lenses. Influence of polymer ratio in the blend film on in vitro drug release behavior in phosphate buffered solution or simulated tear fluid was studied and drug-polymer interaction, erosion and swelling of the blend film were characterized to better understand drug-release mechanism. Storage stability of the inner layer-embedded contact lenses in phosphate buffer solution was also conducted, with ignorable drug loss and negligible change in drug release pattern within 30 days. In vivo pharmacokinetic study in rabbits showed sustained drug release for over 240 h in tear fluid, indicating prolonged drug precorneal residence time. In conclusion, cellulose acetate/Eudragit S100 inner layer-embedded contact lenses are quite promising as controlled-release carrier of highly water soluble drug for ophthalmic delivery. Copyright © 2018 Elsevier B.V. All rights reserved.

[Fitting Monocurve and Bicurve (Soper-McGuire design) rigid gas-permeable contact lenses in keratoconus patients: a prospective randomized comparative clinical trial].

PubMed

Coral-Ghanem, Cleusa; Alves, Milton Ruiz

2008-01-01

To evaluate the clinical performance of Monocurve and Bicurve (Soper-McGuire design) rigid gas-permeable contact lens fitting in patients with keratoconus. A prospective and randomized comparative clinical trial was conducted with a minimum follow-up of six months in two groups of 63 patients. One group was fitted with Monocurve contact lenses and the other with Bicurve Soper-McGuire design. Study variables included fluoresceinic pattern of lens-to-cornea fitting relationship, location and morphology of the cone, presence and degree of punctate keratitis and other corneal surface alterations, topographic changes, visual acuity for distance corrected with contact lenses and survival analysis for remaining with the same contact lens design during the study. During the follow-up there was a decrease in the number of eyes with advanced and central cones fitted with Monocurve lenses, and an increase in those fitted with Soper-McGuire design. In the Monocurve group, a flattening of both the steepest and the flattest keratometric curve was observed. In the Soper-McGuire group, a steepening of the flattest keratometric curve and a flattening of the steepest keratometric curve were observed. There was a decrease in best-corrected visual acuity with contact lens in the Monocurve group. Survival analysis for the Monocurve lens was 60.32% and for the Soper-McGuire was 71.43% at a mean follow-up of six months. This study showed that due to the changes observed in corneal topography, the same contact lens design did not provide an ideal fitting for all patients during the follow-up period. The Soper-McGuire lenses had a better performance than the Monocurve lenses in advanced and central keratoconus.

Atomic force microscopy and scanning electron microscopy analysis of daily disposable limbal ring contact lenses.

PubMed

Lorenz, Kathrine Osborn; Kakkassery, Joseph; Boree, Danielle; Pinto, David

2014-09-01

Limbal ring (also known as 'circle') contact lenses are becoming increasingly popular, especially in Asian markets because of their eye-enhancing effects. The pigment particles that give the eye-enhancing effects of these lenses can be found on the front or back surface of the contact lens or 'enclosed' within the lens matrix. The purpose of this research was to evaluate the pigment location and surface roughness of seven types of 'circle' contact lenses. Scanning electron microscopic (SEM) analysis was performed using a variable pressure Hitachi S3400N instrument to discern the placement of lens pigments. Atomic force microscopy (Dimension Icon AFM from Bruker Nano) was used to determine the surface roughness of the pigmented regions of the contact lenses. Atomic force microscopic analysis was performed in fluid phase under contact mode using a Sharp Nitride Lever probe (SNL-10) with a spring constant of 0.06 N/m. Root mean square (RMS) roughness values were analysed using a generalised linear mixed model with a log-normal distribution. Least square means and their corresponding 95% confidence intervals were estimated for each brand, location and pigment combination. SEM cross-sectional images at 500× and 2,000× magnification showed pigment on the surface of six of the seven lens types tested. The mean depth of pigment for 1-DAY ACUVUE DEFINE (1DAD) lenses was 8.1 μm below the surface of the lens, while the remaining lens types tested had pigment particles on the front or back surface. Results of the atomic force microscopic analysis indicated that 1DAD lenses had significantly lower root mean square roughness values in the pigmented area of the lens than the other lens types tested. SEM and AFM analysis revealed pigment on the surface of the lens for all types tested with the exception of 1DAD. Further research is required to determine if the difference in pigment location influences on-eye performance. © 2014 The Authors. Clinical and Experimental Optometry © 2014 Optometrists Association Australia.

Atomic force microscopy and scanning electron microscopy analysis of daily disposable limbal ring contact lenses

PubMed Central

Lorenz, Kathrine Osborn; Kakkassery, Joseph; Boree, Danielle; Pinto, David

2014-01-01

Background Limbal ring (also known as ‘circle’) contact lenses are becoming increasingly popular, especially in Asian markets because of their eye-enhancing effects. The pigment particles that give the eye-enhancing effects of these lenses can be found on the front or back surface of the contact lens or ‘enclosed’ within the lens matrix. The purpose of this research was to evaluate the pigment location and surface roughness of seven types of ‘circle’ contact lenses. Methods Scanning electron microscopic (SEM) analysis was performed using a variable pressure Hitachi S3400N instrument to discern the placement of lens pigments. Atomic force microscopy (Dimension Icon AFM from Bruker Nano) was used to determine the surface roughness of the pigmented regions of the contact lenses. Atomic force microscopic analysis was performed in fluid phase under contact mode using a Sharp Nitride Lever probe (SNL-10) with a spring constant of 0.06 N/m. Root mean square (RMS) roughness values were analysed using a generalised linear mixed model with a log-normal distribution. Least square means and their corresponding 95% confidence intervals were estimated for each brand, location and pigment combination. Results SEM cross-sectional images at 500× and 2,000× magnification showed pigment on the surface of six of the seven lens types tested. The mean depth of pigment for 1-DAY ACUVUE DEFINE (1DAD) lenses was 8.1 μm below the surface of the lens, while the remaining lens types tested had pigment particles on the front or back surface. Results of the atomic force microscopic analysis indicated that 1DAD lenses had significantly lower root mean square roughness values in the pigmented area of the lens than the other lens types tested. Conclusions SEM and AFM analysis revealed pigment on the surface of the lens for all types tested with the exception of 1DAD. Further research is required to determine if the difference in pigment location influences on-eye performance. PMID:24689948

Risk Factors for Contact Lens Bacterial Contamination During Continuous Wear

PubMed Central

Szczotka-Flynn, Loretta B.; Bajaksouzian, Saralee; Jacobs, Michael R.; Rimm, Alfred

2009-01-01

Purpose Microbial contamination of contact lenses is associated with corneal infection and inflammation. This study determined which microbiological, clinical and demographic factors are associated with bacterial contamination of a silicone hydrogel contact lens when worn for continuous wear. Methods Two hundred five normal subjects were enrolled in the Longitudinal Analysis of Silicone Hydrogel (LASH) Contact Lens Study and were fitted with lotrafilcon A lenses for monthly continuous wear and followed for 1 year. Lenses were aseptically removed after 1 week and 4 months of wear and cultured using an agar sandwich technique. Lids and conjunctiva were routinely cultured at baseline, and after 1 week and 4 months of continuous wear. Lenses and ocular sites were considered to have substantial microbial bioburden when they harbored pathogenic organisms or high levels of commensal organisms. Univariate and multivariate logistic regression analyses were conducted to examine whether substantial conjunctival or lid bioburden, subject demographics, lens wearing history, symptoms, and biomicroscopic signs were associated with lens bioburden. Results About one-third (32.4%) of subjects had substantial bacterial bioburden in either eye across multiple visits. Over half (53.2%) and about one-tenth (11.7%) of subjects had substantial lid and conjunctival bioburden, respectively, and 11.2% discontinued due to discomfort. The adjusted odds ratios (and 95% confidence intervals) for presence of substantial lens bioburden were 2.49 (1.17–5.30), 4.24 (1.45–12.40), and 4.11 (1.17–14.46) for substantial lid bioburden, substantial conjunctival bioburden, and lens discomfort, respectively. Conclusions Bacterial contamination of silicone hydrogel contact lenses is common during continuous wear. Substantial lens bioburden is associated with discomfort precluding successful continuous wear. The presence of substantial lid and conjunctival bioburden are associated with a 2.5 fold and over 4 fold greater risk of substantial lens bioburden and are likely the major routes of contamination. PMID:19786927

Disposable contact lens use as a risk factor for microbial keratitis

PubMed Central

Radford, C.; Minassian, D.; Dart, J.

1998-01-01

AIMS—A case-control study was performed to evaluate soft contact lens (SCL) wear modality as a risk factor for microbial keratitis.
METHODS—Contact lens wearers presenting as new patients to Moorfields Eye Hospital accident and emergency department during a 12 month period completed a self administered questionnaire detailing demographic data and contact lens use habits. Cases were patients with a clinical diagnosis of SCL related microbial keratitis. Controls were SCL users attending with disorders unrelated to contact lens wear. Odds ratios (estimates of relative risks) and 95% confidence limits (CL) were calculated through multivariable logistic regression analysis.
RESULTS—There were 89 cases and 566 controls. A substantially increased risk with 1-4 weekly disposable SCL compared with non-disposable SCL was identified among both daily wear (DW) (odds ratio =3.51, 95% CL 1.60-7.66, p=0.002) and extended wear (odds ratio 4.76, 95% CL 1.52-14.87, p=0.007) users after adjustment for demographic, lens use and hygiene variables. Other significant factors among DW users were "occasional" overnight use, use of chlorine based (as opposed to other chemical) systems in combination with poor storage case hygiene, and irregular disinfection.
CONCLUSION—Properties of some disposable SCL may be partly responsible for these excess risks. It is also possible, however, that this finding is largely a reflection of widespread complacency among patients and practitioners with respect to disposable SCL fitting and use.

 Keywords: microbial keratitis; disposable contact lenses PMID:9924331

Cocamidopropyl betaine.

PubMed

Jacob, Sharon E; Amini, Sadegh

2008-01-01

Cocamidopropyl betaine (CAPB) is an amphoteric synthetic detergent that has been increasingly used in cosmetics and personal hygiene products (eg, shampoos, contact lens solutions, toothpaste detergents, makeup removers, bath gels, skin care products, cleansers, liquid soaps, antiseptics, and gynecologic and anal hygiene products) because it induces relatively mild skin irritation. Delayed T-cell-mediated type IV hypersensitivity reactions to CAPB have been reported, and contact sensitization prevalence is estimated at between 3.0 and 7.2%. The increasing rates of sensitization led to CAPB's being named Allergen of the Year in 2004. Related impurities rendered during the manufacturing process (such as amidoamine and dimethylaminopropylamine) are thought to play a role in sensitization.

Daily versus monthly disposable contact lens: Which is better for ocular surface physiology and comfort?

PubMed

Sapkota, Kishor; Franco, Sandra; Lira, Madalena

2018-06-01

To investigate the effect of soft contact lenses (SCL) wearing modality and lens materials on the changes in conjunctival bulbar and limbal redness and conjunctival and corneal staining after two months of SCL wear. Comfort level was also analyzed. In this longitudinal clinical trial, forty-seven neophyte myopic subjects were fitted with a monthly disposable lens (lotrafilcon-B or comfilcon-A or balafilcon-A) in one eye and a daily disposable lens (nelfilcon-A or stenofilcon-A or nesofilcon-A) in the other eye, randomly selected. Conjunctival bulbar and limbal redness and conjunctival and corneal staining were evaluated before and after lens wear. Effect of lens wearing modality and lens materials on these changes was also determined. Level of comfort was evaluated subjectively twice per day. Comfort level and reduction in end-of-day comfort were compared between different lens wearing modalities and materials. Bulbar and limbal redness and conjunctival and corneal staining were increased (p<0.001) after lens wear, and changes were similar with daily and monthly disposable lens wear (p>0.05). Limbal redness was associated with lens materials, and lotrafilcon-B induced the least among the studied lenses (p<0.05). There was no significant association between the wearing modality and the average comfort level and reduction of end-of-day comfort (p>0.05). Two months of SCL wear increased conjunctival redness, conjunctival and corneal staining, which were not associated with the lens wearing modality. There was a reduction in end-of-day comfort, similar to daily and monthly lenses. The change in limbal redness and reduction in end-of-day comfort were associated with the characteristics of the lens material. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Pseudophakodonesis and corneal endothelial contact: direct observations by high-speed cinematography.

PubMed

Jacobs, P M; Cheng, H; Price, N C

1983-10-01

High-speed cinematography was used to observe the movement of Federov type I lens implants within the anterior chamber. Our measurements suggest that in most patients contact between the lens implant and corneal endothelium does not occur.

Ocular discomfort responses after short periods of contact lens wear.

PubMed

Papas, Eric; Tilia, Daniel; McNally, John; de la Jara, Percy Lazon

2015-06-01

To investigate if contact lens-related discomfort is a function of the time of day at which lenses are worn. This was a randomized, crossover, open-label clinical trial where subjective responses, with and without contact lenses, were assessed every 2 hours during five stages (A to E). Each stage began at the time when subjects would normally have inserted their contact lenses (T0). During stage A, no lenses were worn, whereas in stage B, lenses were worn continuously for 12 hours. In stages C to E, lenses were worn for only 4 hours. Contact lenses were inserted at T0 for stage C, but for stages D and E, lenses were not inserted until T0 + 4 and T0 + 8 hours, respectively. Mixed linear models were used for statistical analysis. In the absence of contact lenses, ocular comfort and dryness remained reasonably constant throughout the observation period. Ocular comfort and dryness decreased during 12 hours of continuous lens wear and became significantly worse from the 8-hour time onward compared with insertion (p < 0.023). There were no significant differences in terms of ocular comfort and dryness between any of the 4-hour lens wear stages (p < 0.82). During each 4-hour stage, both comfort and dryness behaved in a similar fashion (p > 0.05) to the first 4 hours of continuous contact lens wear. Comparing the scores of each of these stages with the no-lens response at the corresponding time showed no significant differences for comfort (p > 0.23) or dryness (p > 0.37). Short periods of wear can be experienced at any time of day without significant change in ocular discomfort and dryness. This suggests that subjective responses at the end of the day are determined by the length of time lenses are in contact with the eye, rather than the time of day at which lenses are worn.

Assessing tear film on soft contact lenses with lateral shearing interferometry.

PubMed

Szczesna, Dorota H

2011-11-01

Evaluating precorneal tear film is one of important clinical measurements for assessing health of anterior eye. Contact lens wear is known to influence the quality of tear film. The aim was to evaluate the applicability of lateral shearing interferometry technique in the noninvasive assessment of the effects of contact lens replacement modality and its water content on tear film stability. Sixteen regular soft contact lens wearers took place in the study. Lateral shearing interferometry measurements, in suppressed blinking conditions, were taken in the mornings and afternoons, after a minimum of 5 hours of lens wear for the daily lenses, and after 2 weeks and 1 month for the fortnightly and monthly lens replacement modalities, respectively. Significant differences (paired bootstrap-based Behrens-Fisher test, P < 0.05) in the tear film surface quality were found between all considered pairs of replacement modalities except for the daily and fortnightly lenses measured in the afternoon of the first day of wear. Significant worsening (paired bootstrap-based Behrens-Fisher test, P < 0.001) of tear film quality was found for the low water content materials. Lateral shearing interferometry is a powerful method for the noninvasive assessment of tear film surface quality on soft contact lenses that may find, in future, its use in the clinical assessment of anterior eye's health.

Contact lens assessment in youth: methods and baseline findings.

PubMed

Lam, Dawn Y; Kinoshita, Beth T; Jansen, Meredith E; Mitchell, G Lynn; Chalmers, Robin L; McMahon, Timothy T; Richdale, Kathryn; Sorbara, Luigina; Wagner, Heidi

2011-06-01

To describe the Contact Lens Assessment in Youth (CLAY) Study design and report baseline data for a multicenter, retrospective, observational chart review of children, teenagers, and young adult soft contact lens (SCL) wearers. Clinical charts of SCL wearers aged 8 to 33 years were reviewed at six colleges of optometry. Data were captured retrospectively for eye care visits from January 2006 through September 2009. Patient demographics, SCL parameters, wearing schedules, care systems, and biomicroscopy findings and complications that interrupted SCL wear were entered into an online database. Charts from 3549 patients (14,276 visits) were reviewed; 78.8% were current SCL wearers and 21.2% were new fits. Age distribution was 8 to <13 years (n = 260, 7.3%), 13 to <18 years (n = 879, 24.8%), 18 to <26 years (n = 1,274, 36.0%), and 26 to <34 years (n = 1,136, 32.0%). The sample was 63.2% females and 37.7% college students. At baseline, 85.2% wore spherical SCLs, 13.5% torics, and 0.1% multifocals. Silicone hydrogel lenses were worn by 39.3% of the cohort. Daily wear was reported by 82.1%, whereas 17.9% reported any or occasional overnight wear. Multipurpose care systems were used by 78.1%, whereas another 9.9% indicated hydrogen peroxide solutions use. This data represent the SCL prescribing and wearing patterns for children, teenager, and young adult SCL wearers who presented for eye care in North American academic clinics. This will provide insight into SCL utilization, change in SCL refractive correction, and risk factors for SCL-related complications by age group.

Contact compliance effects in the frictional response of bioinspired fibrillar adhesives

PubMed Central

Piccardo, Marco; Chateauminois, Antoine; Fretigny, Christian; Pugno, Nicola M.; Sitti, Metin

2013-01-01

The shear failure and friction mechanisms of bioinspired adhesives consisting of elastomer arrays of microfibres terminated by mushroom-shaped tips are investigated in contact with a rigid lens. In order to reveal the interplay between the vertical and lateral loading directions, experiments are carried out using a custom friction set-up in which normal stiffness can be made either high or low when compared with the stiffness of the contact between the fibrillar adhesive and the lens. Using in situ contact imaging, the shear failure of the adhesive is found to involve two successive mechanisms: (i) cavitation and peeling at the contact interface between the mushroom-shaped fibre tip endings and the lens; and (ii) side re-adhesion of the fibre's stem to the lens. The extent of these mechanisms and their implications regarding static friction forces is found to depend on the crosstalk between the normal and lateral loading directions that can result in contact instabilities associated with fibre buckling. In addition, the effects of the viscoelastic behaviour of the polyurethane material on the rate dependence of the shear response of the adhesive are accounted for. PMID:23554349

Tear oxygen under hydrogel and silicone hydrogel contact lenses in humans.

PubMed

Bonanno, Joseph A; Clark, Christopher; Pruitt, John; Alvord, Larry

2009-08-01

To determine the tear oxygen tension under a variety of conventional and silicone hydrogel contact lenses in human subjects. Three hydrogel and five silicone hydrogel lenses (Dk/t = 17 to 329) were coated on the back surface with an oxygen sensitive, bovine serum albumin-Pd meso-tetra (4-carboxyphenyl) porphine complex (BSA-porphine). Each lens type was placed on the right eye of 15 non-contact lens wearers to obtain a steady-state open eye tear oxygen tension using oxygen sensitive phosphorescence decay of BSA-porphine. A closed-eye oxygen tension estimate was obtained by measuring the change in tear oxygen tension after 5 min of eye closure. In separate experiments, a goggle was placed over the lens wearing eye and a gas mixture (PO2 = 51 torr) flowed over the lens to simulate anterior lens oxygen tension during eye closure. Mean open eye oxygen tension ranged from 58 to 133 torr. Closed eye estimates ranged from 11 to 42 torr. Oxygen tension under the goggle ranged from 8 to 48 torr and was higher than the closed eye estimate for six out of the eight lenses, suggesting that the average closed eye anterior lens surface oxygen tension is <51 torr. For Dk/t >30, the measured tear oxygen tension is significantly lower than that predicted from previous studies. The phosphorescence decay methodology is capable of directly measuring the in vivo post lens PO2 of high Dk/t lenses without disturbing the contact lens or cornea. Our data indicate that increasing Dk/t up to and beyond 140 continues to yield increased flux into the central cornea.

An early assessment of silicone hydrogel safety: pearls and pitfalls, and current status.

PubMed

Keay, Lisa; Edwards, Katie; Stapleton, Fiona

2007-11-01

The contact lens industry has evolved and now provides many choices, including continuous wear, overnight orthokeratology, frequent-replacement lenses, daily-disposable lenses, and many alternatives in systems of care and maintenance. Epidemiologic studies to date have shown that how a lens is worn, particularly if worn overnight, can increase the risk of microbial keratitis. However, the risk of silicone hydrogel contact lenses worn on a continuous-wear basis has been evaluated only recently. This article summarizes the recent research data on extended-wear silicone hydrogel lenses and discusses the challenges of early evaluations of silicone hydrogel lens safety. Finally, the relevance of this information is discussed to practitioners and contact lens wearers making choices about the risks and benefits of different products and how they are used.

Microbial adhesion to silicone hydrogel lenses: a review.

PubMed

Willcox, Mark D P

2013-01-01

Microbial adhesion to contact lenses is believed to be one of the initiating events in the formation of many corneal infiltrative events, including microbial keratitis, that occur during contact lens wear. The advent of silicone hydrogel lenses has not reduced the incidence of these events. This may partly be related to the ability of microbes to adhere to these lenses. The aim of this study was to review the published literature on microbial adhesion to contact lenses, focusing on adhesion to silicone hydrogel lenses. The literature on microbial adhesion to contact lenses was searched, along with associated literature on adverse events that occur during contact lens wear. Particular reference was paid to the years 1995 through 2012 because this encompasses the time when the first clinical trials of silicone hydrogel lenses were reported, and their commercial availability and the publication of epidemiology studies on adverse events were studied. In vitro studies of bacterial adhesion to unworn silicone hydrogel lens have shown that generally, bacteria adhere to these lenses in greater numbers than to the hydroxyethyl methacrylate-based soft lenses. Lens wear has different effects on microbial adhesion, and this is dependent on the type of lens and microbial species/genera that is studied. Biofilms that can be formed on any lens type tend to protect the bacteria and fungi from the effects on disinfectants. Fungal hyphae can penetrate the surface of most types of lenses. Acanthamoeba adhere in greater numbers to first-generation silicone hydrogel lenses compared with the second-generation or hydroxyethyl methacrylate-based soft lenses. Microbial adhesion to silicone hydrogel lenses occurs and is associated with the production of corneal infiltrative events during lens wear.

Which soft contact lens power is better for piggyback fitting in keratoconus?

PubMed

Romero-Jiménez, Miguel; Santodomingo-Rubido, Jacinto; Flores-Rodríguez, Patricia; González-Méijome, Jose Manuel

2013-02-01

To evaluate the impact of differente soft contact lens power in the anterior corneal curvature and regularity in subjects with keratoconus. Nineteen subjects (30 eyes) with keratoconus were included in the study. Six corneal topographies were taken with Pentacam Eye System over the naked eye and successively with soft lens (Senofilcon A) powers of -3.00, -1.50, 0.00, +1.50 and +3.00 D. Corneal measurements of mean central keratometry (MCK), maximum tangential curvature (TK), maximum front elevation (MFE) and eccentricity (Ecc) at 6 and 8 mm diameters as well as anterior corneal surface high order aberrations (i.e. total RMS, spherical- and coma-like and secondary astigmatism) were evaluated. Negative- and plano-powered soft lenses flattened (p<0.05 in all cases), whereas positive-powered lenses did not induce any significant changes (p>0.05 in all cases) in MCK in comparison to the naked eye. The TK power decreased with negative lenses (p<0.05 in both cases) and increased with +3.00 D lenses (p=0.03) in comparison to the naked eye. No statistically significant differences were found in MFE with any soft lens power in comparison to the naked eye (p>0.05 in all cases). Corneal eccentricity increased at 8 mm diameter for all lens powers (p<0.05 in all cases). No statistically differences were found in HOA RMS and spherical-like aberration (both p>0.05). Statistically differences were found in coma-like and secondary astigmatism (both p<0.05). Negative-powered soft contact lenses provide a flatter anterior surface in comparison to positive-powered lenses in subjects with keratoconus and thus they might be more suitable for piggyback contact lens fitting. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Pseudophakodonesis and corneal endothelial contact: direct observations by high-speed cinematography.

PubMed Central

Jacobs, P M; Cheng, H; Price, N C

1983-01-01

High-speed cinematography was used to observe the movement of Federov type I lens implants within the anterior chamber. Our measurements suggest that in most patients contact between the lens implant and corneal endothelium does not occur. Images PMID:6615750

Combining primary and piggyback intraocular lenses to treat extreme myopic astigmatism in stable keratoconus following cataract surgery.

PubMed

Goh, Yi Wei; Misra, Stuti; Patel, Dipika V; McGhee, Charles N J

2013-03-01

The majority of those with keratoconus can maximise visual acuity with spectacle or contact lens correction as they age; however, as subjects enter their sixties, cataracts may supervene and contact lens tolerance diminishes with consequent reduction in visual acuity. Following cataract extraction, the complex refractive error associated with keratoconus may not be readily corrected by an intraocular lens alone. This report highlights the planned implantation of a primary posterior chamber toric intraocular lens with a secondary piggyback, sulcus-based, intraocular lens in advanced but stable keratoconus with extreme myopic astigmatism and cataract. © 2013 The Authors. Clinical and Experimental Optometry © 2013 Optometrists Association Australia.

[Giant papillary conjunctivitis].

PubMed

Bischoff, G

2014-05-01

Giant papillary conjunctivitis is an inflammation of the conjunctiva, which is associated with immunological-allergic disorders, but is difficult to integrate as a defined type of illness. The deposits of contact lenses are responsible in predisposed wearers. They induce a special immune answer to their biochemical ingredients. In addition, roughness of the superficial corneal layers and the conjunctiva, even without any contact lenses after filtrating glaucoma surgery, leads to mechanically induced papillary formations. In former days these symptoms of building giant papillae were seen mostly in wearers of soft hydrogel contact lenses. Nowadays manufacturers have developed contact lens systems with a variety of material components, with an increase of protein and lipid deposits. In combination with the observed non-compliance of wearers regarding lens exchange and contact lens hygiene, GPC is an issue which should be taken into consideration again. Georg Thieme Verlag KG Stuttgart · New York.

Quality of image of grating target placed in model of human eye with corneal aberrations as observed through multifocal intraocular lenses.

PubMed

Inoue, Makoto; Noda, Toru; Mihashi, Toshifumi; Ohnuma, Kazuhiko; Bissen-Miyajima, Hiroko; Hirakata, Akito

2011-04-01

To evaluate the quality of the image of a grating target placed in a model eye viewed through multifocal intraocular lenses (IOLs). Laboratory investigation. Refractive (NXG1 or PY60MV) or diffractive (ZM900 or SA60D3) multifocal IOLs were placed in a fluid-filled model eye with human corneal aberrations. A United States Air Force resolution target was placed on the posterior surface of the model eye. A flat contact lens or a wide-field contact lens was placed on the cornea. The contrasts of the gratings were evaluated under endoillumination and compared to those obtained through a monofocal IOL. The grating images were clear when viewed through the flat contact lens and through the central far-vision zone of the NXG1 and PY60MV, although those through the near-vision zone were blurred and doubled. The images observed through the central area of the ZM900 with flat contact lens were slightly defocused but the images in the periphery were very blurred. The contrast decreased significantly in low frequencies (P<.001). The images observed through the central diffractive zone of the SA60D3 were slightly blurred, although the images in the periphery were clearer than that of the ZM900. The images were less blurred in all of the refractive and diffractive IOLs with the wide-field contact lens. Refractive and diffractive multifocal IOLs blur the grating target but less with the wide-angle viewing system. The peripheral multifocal optical zone may be more influential on the quality of the images with contact lens system. Copyright © 2011 Elsevier Inc. All rights reserved.

pH triggered controlled drug delivery from contact lenses: Addressing the challenges of drug leaching during sterilization and storage.

PubMed

Maulvi, Furqan A; Choksi, Harsh H; Desai, Ankita R; Patel, Akanksha S; Ranch, Ketan M; Vyas, Bhavin A; Shah, Dinesh O

2017-09-01

In the present work a novel cyclosporine-loaded Eudragit S100 (pH-sensitive) nanoparticles-laden contact lenses were designed to provide sustained release of cyclosporine at therapeutic rates, without leaching of drug during sterilization and storage period (shelf life). The nanoparticles were prepared by Quasi-emulsion solvent diffusion technique using different weight ratios of cyclosporine to Eudragit S100. The contact lenses with direct drug entrapment were also fabricated (DL-50) for comparison. The percentage swelling and optical transparency of nanoparticles-laden contact lenses were improved in comparison to DL-50 lenses. The nanoparticles-laden contact lenses showed sustained drug release profiles, with inverse relationship to the amount of nanoparticles loaded in the contact lenses. It was interesting to note that nanoparticles form nanochannels/cavities after dissolution of Eudragit S 100 in tear fluid pH=7.4 (in vitro release study). This followed the precipitation of drug in hydrogel matrix of contact lenses. As the amount of nanoparticles loading increased, more number of cavities were formed, which caused the formation of large cavities in contact lens matrix. This in turn precipitated the drug. The nanoparticles-laden contact lenses with 1:1 (drug: Eudragit) weight ratio showed the most promising results of sustaining the drug release up to 156h, without affecting optical and physical properties of contact lenses. Packaging study confirmed that the drug was not leached in packaging solution (buffer, pH=6.5) from nanoparticles-laden lenses during shelf life period. In-vivo study in rabbit tear fluid showed sustained release up to 14days. The study revealed the application of pH-sensitive nanoparticles-laden contact lenses for controlled release of cyclosporine without altering the optical and physical properties of lens material. Copyright © 2017 Elsevier B.V. All rights reserved.

Antibacterial and tribological behavior of self-assembled monolayer on optical lens

NASA Astrophysics Data System (ADS)

Horng, J. H.; Jeng, Y. R.; Wei, C. C.; Tasi, Y. T.

2010-10-01

This paper studies the effects of the antibacterial and anti-adhesion properties of self-assembled monolayers (SAMs) on optical parts. Therefore, the experiments in this study prepared several kinds of SAMs, including alkyl and biphenyl spacer chains with different surface terminal groups (-CH3,-COOH) and head groups (-SH). This study reports the growth of eight self-assembled monolayers on optical parts: OTS, ODS, OTS with antibacterial solution, ODS with antibacterial solution, and pure antibacterial solution, with bio-compatibility. Experimental results regarding the contact angle of five self-assembled monolayers show that ODS with antibacterial illustrated the maximum contact angle 103° 12 hours after reaction. The solutions of OTS, ODS with antibacterial, OTS with antibacterial, and pure anti-bacterial showed contact angles of 102°, 99°, 101°, and 59° respectively. These results indicate that the antibacterial solution has negligible effects on anti-adhesion property of optical lenses. The results of digital optical microscope system analysis show that in the antibacterial experiment of eight kinds of selfassembled monolayers, the OTSanti50% effect cultured for 24 hours achieved the best results, with a growth rate of 12%. The descending order of antibacterial effect is antibacterial 10%>ODS>OTS> antibacterial 50%>ODSanti50%>OTSanti10%>ODSanti10%. In summary, the surface treatment of optical lenses involving OTSanti 50% is the most capable of effectively increasing antifouling and antibacterial functions.

The Use of Extended Wear Contact Lenses in the Aviation Environment: An Army-wide Study.

DTIC Science & Technology

1992-09-01

immediately. Special instructions were provided to these flight surgeons regarding identification, treatment , and disposition of these subjects. This...conjunctivitis; two cases of anterior uveitis /iritis; and one case of a severe allergic reaction. Many of the above conditions were probably not...contact lens related, although the anterior uveitis cases may have been related to a temporary tight lens condition. In order to rule out a tight lens fit

Contact Lens-Induced Discomfort and Protein Changes in Tears.

PubMed

Masoudi, Simin; Stapleton, Fiona Jane; Willcox, Mark Duncan Perry

2016-08-01

Ocular discomfort is among the main causes of contact lens wear discontinuation. This study investigated the association between subjective ocular comfort ratings and diurnal changes in tear protein concentrations with and without contact lens wear. The study was a prospective, open-label, single-group two-staged investigation. Basal tears were collected from 30 experienced contact lens wearers twice a day (morning and evening) using a noninvasive method without lens wear (stage 1) and during wear of Etafilcon A contact lenses (stage 2) for 7 to 10 days. Subjects rated their ocular comfort on a scale of 1 to 100 (with 100 as extremely comfortable) at each time of tear collection. Tears were analyzed using liquid quadrupole mass spectrometry in conjunction with selected reaction monitoring (SRM) method. End-of-day comfort was reduced when wearing lenses (87.8 ± 14.3 AM vs. 79.2 ± 16.6 PM) compared to no lens wear (88.3 ± 12.6 AM vs. 84.7 ± 13.3 PM) (AM vs. PM, p < 0.05). A greater reduction in comfort over the day was seen during lens wear (p < 0.01). The concentration of prolactin-induced protein increased from morning to evening in both stages (mean ± SD; 0.08 ± 0.04 mg/ml, AM vs. 0.09 ± 0.05 mg/ml, PM, p < 0.05). There was no change in the concentration of lactoferrin (1.20 ± 0.77 mg/ml), lysozyme (2.11 ± 1.50 mg/ml), lipocalin 1 (1.75 ± 0.99 mg/ml), or proline-rich protein 4 (0.80 ± 0.49 mg/ml). The prolactin-induced protein concentration was negatively associated with discomfort levels in tears (p < 0.05, r = -0.29). Only the absolute concentration of prolactin-induced protein correlated with subjective comfort ratings. Taking into consideration that prolactin-induced protein can be associated with disruption in water transport in lacrimal glands, our findings may indicate that changes to aqueous secretion are associated with contact lens discomfort.

Biocompatibility in the development of silicone-hydrogel lenses.

PubMed

Jacob, Jean T

2013-01-01

In response to patient demands for extended contact lens wearing times, the contact lens industry has developed novel silicone-hydrogel (SiHy) lens materials that combine the enhanced oxygen permeability of silicone polymers with the water-based comfort of conventional hydrogels. In the past 12 years since the successful launch of these SiHy lenses, much has been learned about their ability to provide the biocompatibility necessary to sustain ocular health and comfort. A review of the unique physiologic requirements for a successful extended wear lens and how the first and current SiHy lenses address them is provided.

Potential sources of bacteria that are isolated from contact lenses during wear.

PubMed

Willcox, M D; Power, K N; Stapleton, F; Leitch, C; Harmis, N; Sweeney, D F

1997-12-01

The aim of this paper was to determine the possible contamination sources of contact lenses during wear. Potential sources of the microbiota that colonized hydrogel contact lenses during wear were examined. The microorganisms that colonize contact lenses were grown, identified, and compared to those microorganisms that colonized the lower lid margins, upper bulbar conjunctiva, hands, and contact lens cases of contact lens wearers. In addition, the incidence of contamination of the domestic water supply in the Sydney area was obtained, and this was compared to the incidence of colonization of contact lenses by microorganisms in general and gram-negative bacteria in particular. There was a wide diversity of bacteria that were isolated from each site sampled. Coagulase-negative staphylococci and Propionibacterium spp. were the most common isolates from all ocular sites examined, and constituted the normal ocular microbiota. Other bacteria, including members of the families Enterobacteriaceae and Pseudomonadaceae, were isolated infrequently from all sites, but most frequently from contact lens cases. Statistical analysis revealed that there was a correlation between the isolation of bacteria from the contact lens and the lower lid margin (p < 0.001). Analysis of this correlation revealed that this was true for the normal microbiota. A correlation was also noted between the colonization of contact lenses by gram-negative bacteria and contamination of the domestic water supply. This study has demonstrated that the likely route for the normal ocular microbiota colonizing contact lenses is via the lid margins, whereas colonization by gram-negative bacteria, including potential agents of microbial keratitis, is likely to be from the domestic water supply.

Proper balance of omega-3 and omega-6 fatty acid supplements with topical cyclosporine attenuated contact lens-related dry eye syndrome.

PubMed

Wang, Ling; Chen, Xi; Hao, Jingfang; Yang, Lu

2016-12-01

Essential fatty acids had been applied in the treatment of dry eye syndrome (DES), but the effects of different combinations of fatty acids have not been investigated. 360 long-term contact lens wearers were included in this double-blinded study. Omega-3 and omega-6 fatty acids were combined in different ratios and supplied to the participants that were randomly divided into six groups, and the effects of different essential fatty acids mixture on DES with or without topical cyclosporine were investigated. More than half of long-term contact lens wearers suffered from DES, which were found to be attenuated by oral supplement of properly balanced O3FA and O6FA fatty acid. The topical cyclosporine treatment considerably inhibited the production of cytokines compared to the cyclosporine negative groups, which further relieved DES. Proper balance of omega-3 and omega-6 fatty acid combination significantly alleviated contact lens-related DES.

Presence of Acanthamoeba in the ocular surface in a Spanish population of contact lens wearers.

PubMed

Rodríguez-Martín, Javier; Rocha-Cabrera, Pedro; Reyes-Batlle, María; López-Arencibia, Atteneri; Sifaoui, Ines; Rizo-Liendo, Aitor; Bethencourt-Estrella, Carlos J; Piñero, José E; Lorenzo-Morales, Jacob

2018-06-26

Pathogenic strains of Acanthamoeba are causative agents of a sight-threatening infection of the cornea known as Acanthamoeba keratitis (AK) which mainly affects contact lens wearers and it is commonly related to poor hygiene of contact lenses and their cases. Moreover, treatment of AK is complex due to the existence of a highly resistant cyst stage and if not diagnosed early has poor prognosis, leading to blindness and/or keratoplasty. Even though AK is increasing worldwide as well as awareness among patients and clinicians, it is still a poorly studied pathogen. Additionally, a remaining question to be answered is whether these opportunistic pathogens are present in the ocular surface of healthy contact lens wearers since they are the main group at risk.In order to carry out this study, sterile Schirmer strip tests were collected from a group of individuals all of them contact lens wearers who were attending a local ophthalmology clinic in Tenerife, Canary Islands, Spain. The collected samples (100 eyes of 50 patients) were cultured in 2% Non-Nutrient Agar (NNA) plates and positive plates (16) were then cultured in axenic conditions for further analyses. Molecular analysis classified all isolated strains belonged to Acanthamoeba genotype T4 and osmotolerance and thermotolerance assays revealed that all strains were potentially pathogenic. In conclusion, the ocular surface of contact lens wearers included in this study was colonized by potentially pathogenic strains of Acanthamoeba and should be considered as a risk for AK infection in this region and worldwide.

Changes in the Eye Microbiota Associated with Contact Lens Wearing

PubMed Central

Price, Kenneth; Albert, Luong; Dodick, Jack; Park, Lisa

2016-01-01

ABSTRACT Wearing contact lenses has been identified as a risk factor for the development of eye conditions such as giant papillary conjunctivitis and keratitis. We hypothesized that wearing contact lenses is associated with changes in the ocular microbiota. We compared the bacterial communities of the conjunctiva and skin under the eye from 58 subjects and analyzed samples from 20 subjects (9 lens wearers and 11 non-lens wearers) taken at 3 time points using a 16S rRNA gene-based sequencing technique (V4 region; Illumina MiSeq). We found that using anesthetic eye drops before sampling decreases the detected ocular microbiota diversity. Compared to those from non-lens wearers, dry conjunctival swabs from lens wearers had more variable and skin-like bacterial community structures (UniFrac; P value = <0.001), with higher abundances of Methylobacterium, Lactobacillus, Acinetobacter, and Pseudomonas and lower abundances of Haemophilus, Streptococcus, Staphylococcus, and Corynebacterium (linear discriminant analysis [LDA] score = >3.0). The results indicate that wearing contact lenses alters the microbial structure of the ocular conjunctiva, making it more similar to that of the skin microbiota. Further research is needed to determine whether the microbiome structure provides less protection from ocular infections. PMID:27006462

Colonization of hydrogel lenses with Streptococcus pneumoniae: risk of development of corneal infiltrates.

PubMed

Sankaridurg, P R; Sharma, S; Willcox, M; Sweeney, D F; Naduvilath, T J; Holden, B A; Rao, G N

1999-05-01

To report the association between colonization of contact lenses with Streptococcus pneumoniae and the observation of corneal infiltrative events in a group of patients wearing disposable hydrogel lenses on an extended-wear schedule. In a prospective clinical trial, 330 patients wore disposable hydrogels on a 6-night extended-wear and replacement schedule. The contact lens, lid, and conjunctival microbiota of these subjects was analyzed at frequent intervals and at the time of an adverse event. Streptococcus pneumoniae was an uncommon isolate and was recovered from only one of the 3,763 conjunctival samples, five (0.1%) of the 3,764 lid samples, and 33 (0.8%) of the 4,315 contact lens samples. Of the 33 lens samples, 10 (30%) were associated with corneal infiltrative events. Many of the events were mild inflammatory responses and resolved rapidly on discontinuation of lens wear. The presence of S. pneumoniae on the contact lens was associated with a significant risk of development of corneal infiltrates (odds ratio, 3.0; p = 0.0227, logistic-regression analysis). Presence of S. pneumoniae on hydrogel lenses is a significant risk factor for the development of corneal infiltrates.

Soft Contact Lens Wear at Altitude: Effects of Hypoxia

DTIC Science & Technology

1988-01-01

conjunctiva (2). If the edema is severe, breakdown of some and aircraft with cabin pressures equivalent to lower altitudes, of the epithelial cells from...debris, conjunctival injection, and corneal epithelial of hydrogel lenses. International Contact Lens Clinic. 1983. staining, showed heightened...cornea may be severe enough to affect vision stnae accompanying the wearing of hydrogel lenses. Am. J. and preclude wearing soft contact lenses during

Acanthamoeba: An Overview of the Challenges to the Development of a Consensus Methodology of Disinfection Efficacy Testing for Contact Lens Care Products.

PubMed

Brocious, Jeffrey; Tarver, Michelle E; Hampton, Denise; Eydelman, Malvina

2018-04-24

With the increasing incidence of more pathogens that can cause microbial keratitis (MK), it is necessary to periodically reassess disinfection multipurpose solutions testing requirements to ensure that relevant organisms to challenge them are being used. Current testing protocols have included common pathogens such as Pseudomonas aeruginosa, Staphylococcus aureus, Serratia marcescens, Candida albicans, and Fusarium solani but have omitted less common pathogens such as Acanthamoeba. Specifically, Acanthamoeba sp. has recently been identified as a prevalent cause of MK in certain countries. Developing an appropriate protocol for this unique organism presents a challenge, given its two distinct life stages, methods to grow the organism, encystment techniques, and many other parameters that can affect testing outcomes. Therefore, the appropriate combination of these parameters is crucial to developing a protocol that ensures consistent, accurate results. The FDA has recognized the importance of establishing a standardized testing protocol for this pathogen and embarked on research efforts to provide a recommended testing protocol for testing contact lens care products.

Quantity of protein deposited on hydrogel contact lenses and its relation to visible protein deposits.

PubMed

Myers, R I; Larsen, D W; Tsao, M; Castellano, C; Becherer, L D; Fontana, F; Ghormley, N R; Meier, G

1991-10-01

The purposes of this study were to determine if the quantity of protein deposited (QPD) upon hydrogel lenses was affected by enzymatic cleaning and to test the potential relation between QPD and visible protein deposition (VPD) and change. Seventy-four contact lens patients classified as "heavy depositors" wore new lenses for an average of 80 (SD = 32) days. Cleaning and disinfection solutions varied. One lens was cleaned weekly by a papain enzymatic treatment. The distribution of QPD measurements was bimodal and was related to the FDA material for nonionic, low water content lenses (FDA Materials Group no. 1). The mean deposition was 45 micrograms/cm2 (N = 112) compared with that of ionic, high water content lenses (FDA Materials Group no. 4), which was 1010 micrograms/cm2 (N = 30). VPD distributions were the same for the FDA Group no. 1 and no. 4 lenses. Enzymatic treatment did not significantly reduce QPD; however, enzymatic treatment did reduce VPD. Thus QPD and VPD are independent phenomena and possible reasons for this are given.

Consequences of wear interruption for discomfort with contact lenses.

PubMed

Papas, Eric B; Tilia, Daniel; Tomlinson, Daniel; Williams, Josh; Chan, Eddy; Chan, Jason; Golebiowski, Blanka

2014-01-01

To establish whether increased end-of-day discomfort during soft contact lens wear is associated with short-term changes occurring to the lens itself. Twenty-seven subjects wore hydrogel lenses (Focus Dailies; Alcon) bilaterally for 10 hours on two separate days. Comfort was reported using 1-100 numerical rating scales (1 = intolerable discomfort, 100 = lens cannot be felt). Day 1 ratings were taken before lens insertion and at 0.05, 5, and 10 hours post-insertion. Day 2 ratings occurred at similar times, but lenses were removed after the 5-hour assessment and either reinserted (n = 14) or newly replaced (n = 12). An additional rating was taken 5 minutes after re-insertion. Wear then continued to the 10-hour point. In a separate study, 24 different subjects repeated these procedures using a silicone hydrogel lens (AirOptix Aqua; Alcon) with wear taking place on 3 days to permit lens replacement to be with existing as well as new lenses in all subjects. For hydrogel lenses, comfort scores (mean ± 95% CI) reported after 10 hours were 79.4 ± 8.3 when lenses were worn un-replaced, compared with 73.2 ± 9.2 for replacement with the existing lens. When replacement was with a brand new lens, the corresponding values were 72.9 ± 10.9 (un-replaced) versus 69.2 ± 12.8 (new lens replacement). For silicone hydrogel lenses, 10-hour comfort was 90.3 ± 3.2 (un-replaced) versus 92.2 ± 2.9 (replacement with existing lens) versus 90.0 ± 3.3 (replacement with new lens). Differences between replacement conditions were not significant in any case (analysis of variance, p > 0.05). Final comfort was not influenced by replacing lenses midway through the wearing period. Comfort decrements experienced by users of these daily contact lenses towards the later part of the wearing period are not caused by changes occurring to the lenses on this time scale. Possible alternative etiological factors include a fatigue-like response in one or more ocular tissues or stimulation of ocular surface nociceptors induced by the presence of the contact lens.

Lid wiper microvascular responses as an indicator of contact lens discomfort

PubMed Central

Deng, Zhihong; Wang, Jianhua; Jiang, Hong; Fadli, Zohra; Liu, Che; Tan, Jia; Zhou, Jin

2016-01-01

Purpose To analyze quantitatively the alterations in the microvascular network of the upper tarsal conjunctiva, lid wiper, and bulbar conjunctiva relative to ocular discomfort after contact lens wear. Design A prospective, cross-over clinical study. Methods Functional slit-lamp biomicroscopy (FSLB) was used to image the microvascular network of the upper tarsal conjunctiva, lid wiper, and bulbar conjunctiva. The microvascular network was automatically segmented, and fractal analyses were performed to yield the fractal dimension (Dbox) that represented vessel density. Sixteen healthy subjects (nine female and seven male) with an average age of 35.5 ± 6.7 years old (mean ± standard deviation) were recruited. The right eye was imaged at 9 AM and 3 PM at the first visit (Day 1) when the subject was not wearing contact lenses. During the second visit (Day 2), the right eye was fit with a contact lens for 6 h. Microvascular imaging was performed before (at 9 AM) and after lens wear (at 3 PM). Ocular comfort was rated using a 50-point visual analogue scale before and after 6 h of lens wear, and its relationships with microvascular parameters were analyzed. Results There were no significant differences in Dbox among the upper tarsal conjunctiva, lid wiper, and bulbar conjunctiva among the measurements at 9 AM (Day 1 and Day 2) and 3 PM (Day 1) when the subjects were not wearing the lenses (P > 0.05), whereas after 6 h of lens wear, the microvascular network densities were increased in all three of these locations. Dbox of the lid wiper increased from 1.411 ± 0.116 to 1.548 ± 0.079 after 6 h of contact lens wear (P < 0.01). Dbox of the tarsal conjunctiva was 1.731 ± 0.026 at baseline and increased to 1.740 ± 0.030 (P < 0.05). Dbox of the bulbar conjunctiva increased from 1.587 ± 0.059 to 1.632 ± 0.060 (P < 0.001). The decrease in ocular discomfort was strongly related to the Dbox change in the lid wiper (r = 0.61, P < 0.05). There were no correlations between the changes of ocular comfort and the microvascular network densities of either the tarsal or bulbar conjunctivas (P > 0.05). Conclusion This study is the first to show that the microvascular network of the lid wiper can be quantitatively analyzed in contact lens wearers. The microvascular responses of the lid wiper were significantly correlated with contact lens discomfort. PMID:27542928

Determination of the total attenuation coefficient for six contact lens materials using the Beer-Lambert law.

PubMed

Hull, C C; Crofts, N C

1996-03-01

The Beer-Lambert law has been used to determine the total attenuation coefficient, mu t, of three hard and three soft contact lens materials. The three hard contact lens materials were PMMA, Polycon II and Boston IV whereas the 3 soft materials were chosen with differing water contents of 38, 55 and 70%, respectively. The total attenuation coefficients of all six materials were obtained from measurements of the axial transmission at 632.8 nm of a series of plano powered lenses varying in axial thickness from 0.5 to 3.5 mm. The value of the total attenuation coefficient depends on both scattering and absorption and hence PMMA and Boston IV, which both incorporated a handling tint, showed significantly higher values (P < 0.0001) of mu t (0.562 +/- 0.010 mm-1 and 0.820 +/- 0.008 mm-1, respectively) than Polycon II (mu t = 0.025 +/- 0.005 mm-1). A comparison between Polycon II and the three hydrated soft contact lens materials showed a significant increase (P < 0.02) in the total attenuation coefficients for the 38% and 55% water content materials, and a weakly significant increase for the 70% water content soft lens material (P < 0.1). On the assumption that the absorption coefficients of these four materials are approximately constant, then this change would be due to an increase in the scattering coefficient of the material and could contribute to an increase in intraocular scatter. No significant difference (P > 0.5) was found between any of the hydrated soft contact lens materials tested.

Tear Oxygen Under Hydrogel and Silicone Hydrogel Contact Lenses in Humans

PubMed Central

Bonanno, Joseph A.; Clark, Christopher; Pruitt, John; Alvord, Larry

2011-01-01

Purpose To determine the tear oxygen tension under a variety of conventional and silicone hydrogel contact lenses in human subjects. Methods Three hydrogel and five silicone hydrogel lenses (Dk/t = 17 to 329) were coated on the back surface with an oxygen sensitive, bovine serum albumin-Pd meso-tetra (4-carboxyphenyl) porphine complex (BSA-porphine). Each lens type was placed on the right eye of 15 non-contact lens wearers to obtain a steady-state open eye tear oxygen tension using oxygen sensitive phosphorescence decay of BSA-porphine. A closed-eye oxygen tension estimate was obtained by measuring the change in tear oxygen tension after 5 min of eye closure. In separate experiments, a goggle was placed over the lens wearing eye and a gas mixture (PO2 = 51 torr) flowed over the lens to simulate anterior lens oxygen tension during eye closure. Results Mean open eye oxygen tension ranged from 58 to 133 torr. Closed eye estimates ranged from 11 to 42 torr. Oxygen tension under the goggle ranged from 8 to 48 torr and was higher than the closed eye estimate for six out of the eight lenses, suggesting that the average closed eye anterior lens surface oxygen tension is <51 torr. For Dk/t >30, the measured tear oxygen tension is significantly lower than that predicted from previous studies. Conclusions The phosphorescence decay methodology is capable of directly measuring the in vivo post lens PO2 of high Dk/t lenses without disturbing the contact lens or cornea. Our data indicate that increasing Dk/t up to and beyond 140 continues to yield increased flux into the central cornea. PMID:19609230

Mechanically triggered solute uptake in soft contact lenses.

PubMed

Tavazzi, Silvia; Ferraro, Lorenzo; Fagnola, Matteo; Cozza, Federica; Farris, Stefano; Bonetti, Simone; Simonutti, Roberto; Borghesi, Alessandro

2015-06-01

Molecular arrangement plays a role in the diffusion of water and solutes across soft contact lenses. In particular, the uptake of solutes in hydrated contact lenses can occur as long as free water is available for diffusion. In this work, we investigated the effect of mechanical vibrations of low frequency (200 Hz) on the solute uptake. Hyaluronan, a polysaccharide of ophthalmic use, was taken as example of solute of interest. For a specific water-hydrated hydrogel material, differential scanning calorimetry experiments showed that a large fraction of the hydration water accounted for loosely-bound water, both before and after one week of daily-wear of the lenses. The size (of the order of magnitude of few hundreds of nanometers) of hyaluronan in aqueous solution was found to be less than the size of the pores of the lens observed by scanning electron microscopy. However, solute uptake in already-hydrated lenses was negligible by simple immersion, while a significant increase occurred under mechanical vibrations of 200 Hz, thus providing experimental evidence of mechanically triggered enhanced solute uptake, which is attributed to the release of interfacial loosely-bound water. Also other materials were taken into consideration. However, the effectiveness of mechanical vibrations for hyaluronan uptake is restricted to lenses containing interfacial loosely-bound water. Indeed, loosely-bound water is expected to be bound to the polymer with bonding energies of the order of magnitude of 10-100 J/g, which are compatible with the energy input supplied by the vibrations. Copyright © 2015 Elsevier B.V. All rights reserved.

Colored cosmetic contact lenses: an unsafe trend in the younger generation.

PubMed

Singh, Shwetambari; Satani, Dipali; Patel, Amit; Vhankade, Ravinder

2012-07-01

To identify the microbiological profile and evaluate the clinical course and outcomes in patients who developed severe infectious keratitis after colored cosmetic contact lens wear. This case series includes 13 patients who developed severe infectious keratitis after colored cosmetic contact lens wear. A detailed history regarding contact lens availability and storage and handling techniques was taken. All patients underwent standard diagnostic microbiological evaluation followed by culture-guided topical antimicrobial therapy. Of 13 patients, 8 were male and 5 were female, with mean age at presentation of 19 ± 3.8 years. All patients were emmetropic, and lenses were worn solely for cosmetic purposes. Seven lenses were dispensed without prescription or fitting from an unlicensed optical shop, 5 patients had shared lenses with friends/relatives, and 1 patient obtained the lens from the garbage. None of the patients followed the recommended contact lens handling and storage techniques. The causative microorganisms included Pseudomonas aeruginosa (54%), Staphylococcus aureus (25%), and Staphylococcus epidermidis (17%), with 1 case of viral keratitis. In 62% of cases, ulcer size was ≥5 × 5 mm and posttreatment corrected visual acuity was 6/24 or less. All patients responded well to topical antimicrobials, and none required surgical intervention. Over-the-counter use of decorative lenses as a cosmetic aid is rapidly increasing. Easy and unmonitored availability of these cosmetic lenses is followed by severe sight-threatening complications in young emmetropic individuals.

Ultra-wide field imaging system and traditional retinal examinations for screening fundus changes after cataract surgery.

PubMed

Peng, Jie; Zhang, Qi; Jin, Hai-Ying; Lu, Wu-Yi; Zhao, Pei-Quan

2016-01-01

To compare the results of non-mydriatic ultra-wide field imaging system, mydriatic slit-lamp lens (Volk +90 D) and mydriatic Goldmann three-mirror contact lens examinations in screening fundus lesions among patients after cataract surgery. Non-mydriatic images were obtained with an Optomap panoramic 200Tx (Optomap 200Tx) 3d after surgery and graded by a blinded ophthalmologist. A mydriatic slit-lamp lens examination was performed by another blinded retinal specialist on the same day. A third blinded retinal specialist examined patients two weeks after surgery using a Goldmann three-mirror contact lens. In total, 160 patients (184 eyes) were examined, and 66, 69, and 75 cases of retinal lesion(s) were identified using the Optomap 200Tx, slit-lamp lens, and Goldmann three-mirror contact lens, respectively. In 13 cases, fundus changes were sight-threatening. The results obtained by Optomap 200Tx examination and by mydriatic slit-lamp lens examination have good consistency (P=0.375, Kappa=0.942). The mydriatic Goldmann three-mirror lens examination revealed more fundus lesions but are consistent with Optomap 200Tx (P=0.004, Kappa=0.897) and mydriatic slit-lamp lens examination (P=0.031, Kappa=0.932). Early post-operative fundus screening in cataract patients is extremely important and necessary to prevent further vision loss. Wide-field imaging is a feasible and convenient tool for fundus examination that can be used as a primary screening method among patients after cataract surgery.

Note: Simple hysteresis parameter inspector for camera module with liquid lens

NASA Astrophysics Data System (ADS)

Chen, Po-Jui; Liao, Tai-Shan; Hwang, Chi-Hung

2010-05-01

A method to inspect hysteresis parameter is presented in this article. The hysteresis of whole camera module with liquid lens can be measured rather than a single lens merely. Because the variation in focal length influences image quality, we propose utilizing the sharpness of images which is captured from camera module for hysteresis evaluation. Experiments reveal that the profile of sharpness hysteresis corresponds to the characteristic of contact angle of liquid lens. Therefore, it can infer that the hysteresis of camera module is induced by the contact angle of liquid lens. An inspection process takes only 20 s to complete. Thus comparing with other instruments, this inspection method is more suitable to integrate into the mass production lines for online quality assurance.

Extended release of high molecular weight hydroxypropyl methylcellulose from molecularly imprinted, extended wear silicone hydrogel contact lenses.

PubMed

White, Charles J; McBride, Matthew K; Pate, Kayla M; Tieppo, Arianna; Byrne, Mark E

2011-08-01

Symptoms of contact lenses induced dry eye (CLIDE) are typically treated through application of macromolecular re-wetting agents via eye drops. Therapeutic soft contact lenses can be formulated to alleviate CLIDE symptoms by slowly releasing comfort agent from the lens. In this paper, we present an extended wear silicone hydrogel contact lens with extended, controllable release of 120 kDa hydroxypropyl methylcellulose (HPMC) using a molecular imprinting strategy. A commercial silicone hydrogel lens was tailored to release approximately 1000 μg of HPMC over a period of up to 60 days in a constant manner at a rate of 16 μg/day under physiological flowrates, releasing over the entire range of continuous wear. Release rates could be significantly varied by the imprinting effect and functional monomer to template ratio (M/T) with M/T values 0, 0.2, 2.8, 3.4 corresponding to HPMC release durations of 10, 13, 23, and 53 days, respectively. Lenses had high optical quality and adequate mechanical properties for contact lens use. This work highlights the potential of imprinting in the design and engineering of silicone hydrogel lenses to release macromolecules for the duration of wear, which may lead to decreased CLIDE symptoms and more comfortable contact lenses. Copyright © 2011 Elsevier Ltd. All rights reserved.

National Apprenticeship and Training Standards for Optical Technician (Contact Lens Technician). Revised.

ERIC Educational Resources Information Center

Employment and Training Administration (DOL), Washington, DC. Bureau of Apprenticeship and Training.

These national standards are intended to serve as a guide for the establishment of thorough and complete apprenticeship programs to produce trained optical technicians (contact lens technicians). Covered in the individual sections are the following topics: definitions, qualifications for apprenticeship, credit for previous experience, continuity…

Surface modification of model hydrogel contact lenses with hyaluronic acid via thiol-ene "click" chemistry for enhancing surface characteristics.

PubMed

Korogiannaki, Myrto; Zhang, Jianfeng; Sheardown, Heather

2017-10-01

Discontinuation of contact lens wear as a result of ocular dryness and discomfort is extremely common; as many as 26% of contact lens wearers discontinue use within the first year. While patients are generally satisfied with conventional hydrogel lenses, improving on-eye comfort continues to remain a goal. Surface modification with a biomimetic, ocular friendly hydrophilic layer of a wetting agent is hypothesized to improve the interfacial interactions of the contact lens with the ocular surface. In this work, the synthesis and characterization of poly(2-hydroxyethyl methacrylate) surfaces grafted with a hydrophilic layer of hyaluronic acid are described. The immobilization reaction involved the covalent attachment of thiolated hyaluronic acid (20 kDa) on acrylated poly(2-hydroxyethyl methacrylate) via nucleophile-initiated Michael addition thiol-ene "click" chemistry. The surface chemistry of the modified surfaces was analyzed by Fourier transform infrared spectroscopy-attenuated total reflectance and X-ray photoelectron spectroscopy. The appearance of N (1s) and S (2p) peaks on the low resolution X-ray photoelectron spectroscopy spectra confirmed successful immobilization of hyaluronic acid. Grafting hyaluronic acid to the poly(2-hydroxyethyl methacrylate) surfaces decreased the contact angle, the dehydration rate, and the amount of nonspecific sorption of lysozyme and albumin in comparison to pristine hydrogel materials, suggesting the development of more wettable surfaces with improved water-retentive and antifouling properties, while maintaining optical transparency (>92%). In vitro testing also showed excellent viability of human corneal epithelial cells with the hyaluronic acid-grafted poly(2-hydroxyethyl methacrylate) surfaces. Hence, surface modification with hyaluronic acid via thiol-ene "click" chemistry could be useful in improving contact lens surface properties, potentially alleviating symptoms of contact lens related dryness and discomfort during wear.

Risk factors for moderate and severe microbial keratitis in daily wear contact lens users.

PubMed

Stapleton, Fiona; Edwards, Katie; Keay, Lisa; Naduvilath, Thomas; Dart, John K G; Brian, Garry; Holden, Brien

2012-08-01

To establish risk factors for moderate and severe microbial keratitis among daily contact lens (CL) wearers in Australia. A prospective, 12-month, population-based, case-control study. New cases of moderate and severe microbial keratitis in daily wear CL users presenting in Australia over a 12-month period were identified through surveillance of all ophthalmic practitioners. Case detection was augmented by record audits at major ophthalmic centers. Controls were users of daily wear CLs in the community identified using a national telephone survey. Cases and controls were interviewed by telephone to determine subject demographics and CL wear history. Multiple binary logistic regression was used to determine independent risk factors and univariate population attributable risk percentage (PAR%) was estimated for each risk factor. Independent risk factors, relative risk (with 95% confidence intervals [CIs]), and PAR%. There were 90 eligible moderate and severe cases related to daily wear of CLs reported during the study period. We identified 1090 community controls using daily wear CLs. Independent risk factors for moderate and severe keratitis while adjusting for age, gender, and lens material type included poor storage case hygiene 6.4× (95% CI, 1.9-21.8; PAR, 49%), infrequent storage case replacement 5.4× (95% CI, 1.5-18.9; PAR, 27%), solution type 7.2× (95% CI, 2.3-22.5; PAR, 35%), occasional overnight lens use (<1 night per week) 6.5× (95% CI, 1.3-31.7; PAR, 23%), high socioeconomic status 4.1× (95% CI, 1.2-14.4; PAR, 31%), and smoking 3.7× (95% CI, 1.1-12.8; PAR, 31%). Moderate and severe microbial keratitis associated with daily use of CLs was independently associated with factors likely to cause contamination of CL storage cases (frequency of storage case replacement, hygiene, and solution type). Other factors included occasional overnight use of CLs, smoking, and socioeconomic class. Disease load may be considerably reduced by attention to modifiable risk factors related to CL storage case practice. Copyright © 2012 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Paraxial ray solution for liquid-filled variable focus lenses

NASA Astrophysics Data System (ADS)

Wang, Lihui; Oku, Hiromasa; Ishikawa, Masatoshi

2017-12-01

We propose a general solution for determining the cardinal points and effective focal length of a liquid-filled variable focus lens to aid in understanding the dynamic behavior of the lens when the focal length is changed. A prototype of a variable focus lens was fabricated and used to validate the solution. A simplified solution was also presented that can be used to quickly and conveniently calculate the performance of the lens. We expect that the proposed solutions will improve the design of optical systems that contain variable focus lenses, such as machine vision systems with zoom and focus functions.

The effect of rebamipide ophthalmic suspension on ocular surface mucins in soft contact lens wearers.

PubMed

Shigeyasu, Chika; Yamada, Masakazu; Akune, Yoko; Fukui, Masaki

2017-12-13

To evaluate the changes in ocular surface mucins with 2%rebamipide ophthalmic suspension treatment in soft contact lens (SCL) wearers. Rebamipide suspension is a mucin secretagogue approved for the treatment of dry eye syndrome in Japan. In this study, the fluorescence intensity of wheat germ agglutinin conjugate of fluorescein (F-WGA) was used as a marker of membrane-associated mucins, and sialic acid concentration in tear fluids as a marker of secreted mucins. Thirty-two eyes of 16 SCL wearers with discomfort were treated with rebamipide suspension at a dose of one drop in each eye four times daily for two weeks. The parameters of clinical efficacy were tear break-up time, fluorescein staining scores for the cornea and conjunctiva, and Schirmer test values. Fluorescence intensities in the central cornea were measured by fluorophotometry after the application of 5% F-WGA solution. Tears collected by Schirmer test strips were analyzed by high-performance liquid chromatography, and the concentrations of sialic acid, total protein, and the four major tear proteins, namely secretory IgA, lactoferrin, lipocalin-1, and lysozyme were measured. Significant increases in F-WGA fluorescence intensities (p < 0.005) were seen in the corneal surfaces. Sialic acid concentrations increased over time; however, the differences were not statistically significant. Except for a slight increase in kerato-conjunctival staining scores (p < 0.05) and secretory IgA (p < 0.05), no other significant differences were seen among clinical parameters or tear proteins. Topical application of rebamipide suspension significantly increased F-WGA intensity, a marker of membrane-associated mucins in SCL wearers. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Corneal inflammatory events with daily silicone hydrogel lens wear.

PubMed

Szczotka-Flynn, Loretta; Jiang, Ying; Raghupathy, Sangeetha; Bielefeld, Roger A; Garvey, Matthew T; Jacobs, Michael R; Kern, Jami; Debanne, Sara M

2014-01-01

This study aimed to determine the probability and risk factors for developing a corneal inflammatory event (CIE) during daily wear of lotrafilcon A silicone hydrogel contact lenses. Eligible participants (n = 218) were fit with lotrafilcon A lenses for daily wear and followed up for 12 months. Participants were randomized to either a polyhexamethylene biguanide-preserved multipurpose solution or a one-step peroxide disinfection system. The main exposures of interest were bacterial contamination of lenses, cases, lid margins, and ocular surface. Kaplan-Meier (KM) plots were used to estimate the cumulative unadjusted probability of remaining free from a CIE, and multivariate Cox proportional hazards regression was used to model the hazard of experiencing a CIE. The KM unadjusted cumulative probability of remaining free from a CIE for both lens care groups combined was 92.3% (95% confidence interval [CI], 88.1 to 96.5%). There was one participant with microbial keratitis, five participants with asymptomatic infiltrates, and seven participants with contact lens peripheral ulcers, providing KM survival estimates of 92.8% (95% CI, 88.6 to 96.9%) and 98.1% (95% CI, 95.8 to 100.0%) for remaining free from noninfectious and symptomatic CIEs, respectively. The presence of substantial (>100 colony-forming units) coagulase-negative staphylococci bioburden on lid margins was associated with about a five-fold increased risk for the development of a CIE (p = 0.04). The probability of experiencing a CIE during daily wear of lotrafilcon A contact lenses is low, and symptomatic CIEs are rare. Patient factors, such as high levels of bacterial bioburden on lid margins, contribute to the development of noninfectious CIEs during daily wear of silicone hydrogel lenses.

[Trends of refractive correction in the Japanese Ground Self-Defense Forces: examination after the Great East Japan earthquake].

PubMed

Harimoto, Kouzo; Kato, Naoko; Shoji, Takuhei; Goto, Hiroya; Tokuno, Shinichi; Fujii, Manabu; Takeuchi, Masaru

2014-02-01

To investigate the trends in refractive correction in Japanese Ground Self-Defense Forces' (JGSDF) soldiers. A questionnaire was distributed to 519 soldiers of the Camp Funaoka in the northeastern region. Five hundred and sixteen subjects (99.4%) responded. In total, 246 soldiers (47.7%) wore spectacles or contact lenses. Among the contact lens wearers, 52 had experienced problems previously and 35 reported problems that occurred during military exercises. With regard to military exercises, 66.9% and 63.5% of the spectacle or disposable soft contact lens-users reported inconvenience. Among contact lens users, 33.1% reported that they changed to new sterilized contact lenses only occasionally and 61.9% did not change their contact lenses at all during exercises. During disaster-relief work, subjects worried 'very' (21.5%) or 'somewhat' (46.9%) about problems associated with their spectacles or contact lenses. Twenty-four had undergone refractive surgery (4.9%). About one-half of the JGSDF soldiers surveyed required refractive correction. Attention to convenient and safe refractive correction in the military is warranted.

Pigment dispersion syndrome associated with intraocular lens implantation: a new surgical technique.

PubMed

Canut Jordana, M Isabel; Pérez Formigó, Daniel; Abreu González, Rodrigo; Nadal Reus, Jeroni

2010-11-11

We report the case of a myopic patient who, after intraocular lens transplant in the posterior chamber, suffered elevated intraocular pressure due to pigment dispersion, with recurrent episodes of blurred vision. The patient was treated with a new surgical technique that can avoid potential iridolenticular contact. Complete ophthalmologic examination and optical coherence tomography (OCT) of the anterior segment were performed. Contact between the pigmentary epithelium and the iris with an intraocular lens was revealed by utrasound biomicroscopy and OCT. In this case, Nd:YAG laser iridotomy and laser iridoplasty were not effective for iridolenticular separation and control of the pigment dispersion. We propose a new technique: stitches on the surface of the iris to obtain good iridolenticular separation and good intraocular pressure control. Stitches on the iris surface should be considered as optional therapy in pigmentary glaucoma secondary to intraocular lens implantation. This surgical technique can avoid potential iridolenticular contacts more definitively.

21 CFR 886.5928 - Soft (hydrophilic) contact lens care products.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Soft (hydrophilic) contact lens care products. 886.5928 Section 886.5928 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... means of heat. (b) Classification. Class II (Special Controls) Guidance Document: “Guidance for Industry...

Task Analysis in Optical & Contact Lens Dispensing. Dispensing Opticians.

ERIC Educational Resources Information Center

Hrushowy, Eugene; Stanley, Dale

A task force of opticians and educators in British Columbia was assembled to determine the knowledge and skills required of dispensing opticians and contact lens specialists. The ideas generated by the task force were analyzed and distilled into the standardized tasks listed in this document, using Krathwohl's taxonomy. The document contains 36…

Polymicrobial and microsporidial keratitis in a patient using Boston scleral contact lens for Sjogren's syndrome and ocular cicatricial pemphigoid.

PubMed

Fernandes, Merle; Sharma, Savitri

2013-04-01

To report a rare case of microsporidial and polymicrobial keratitis in a patient with Sjogren's syndrome and ocular cicatricial pemphigoid. This is a descriptive case report. A 66-year-old lady diagnosed with Sjogren's syndrome (SS) and ocular cicatricial pemphigoid (OCP) presented to us with microbial keratitis after using a Boston sclera contact lens for a painful epithelial defect. After 9 days of medical treatment, she underwent therapeutic penetrating keratoplasty. 10% potassium hydroxide and calcofluor white wet mount revealed microsporidial spores. Gram positive cocci and Gram variable bacilli on Gram stain were identified as Staphylococcus epidermidis and Corynebacterium accolens in culture. Histopathological examination of the corneal tissue confirmed the presence of microsporidial spores. Microsporidal keratitis can occur in patients with severe ocular surface disease due to SS and OCP. Predisposing factors include dry eye, local and systemic immunosuppression and Boston scleral contact lens. Early surgical intervention may be needed to eradicate the infection. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Severe keratomalacia after 12 months of continuous hydrogel contact lens wear in a psychiatric patient.

PubMed

Rico-Sergado, Laura; Pérez-Canales, Jose L; Pérez-Santonja, Juan J; Cigüenza-Sancho, Sonia

2015-04-01

A 53-year-old cachectic patient diagnosed with major depressive disorder was referred to our department for evaluation of a visible deformation of the right eye. She had been wearing hydrogel contact lenses on a continuous basis without removal for the last 12 months, influenced by low self-esteem and social isolation. Slit-lamp examination of the right eye showed a conical cornea, extensive neovascularization, severe stromal melting with descemetocele formation and forward bulging of the iris. Examination of the left eye revealed multiple corneal opacities, deep stromal neovascularization and anterior chamber inflammation. No sign of infection was present. Vitamin A deficiency was suspected and later confirmed. The patient required evisceration of the right eye and psychiatric treatment. Inflammatory signs of the left eye resolved within 1 week of initiating treatment. This case illustrates the synergistic effect of soft contact lens abuse and vitamin A deficiency in a psychiatric patient, and emphasizes the importance of instructing vulnerable patients on appropriate lens use and care. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Interpreting the corneal response to oxygen: Is there a basis for re-evaluating data from gas-goggle studies?

PubMed

Papas, Eric B; Sweeney, Deborah F

2016-10-01

When anoxia (0% oxygen) is created within a gas-tight goggle, ocular physiological responses, including corneal swelling, limbal hyperaemia and pH change, are known to vary, depending on the presence or absence of a low, oxygen transmissibility contact lens. A new theory is proposed to account for this discrepancy based on the concept of lid derived oxygen, whereby oxygen originating from the vascular plexus of the palpebral conjunctiva supplements that available to the ocular surface in an open, normally blinking eye, even when the surrounding gaseous atmosphere is anoxic. The effect of a lid derived contribution to corneal oxygenation was assessed by using existing experimental data to model open-eye, corneal swelling behavior as a function of atmospheric oxygen content, both with and without the presence of a contact lens. These models predict that under atmospheric anoxia, contact lens wear results in 13.2% corneal swelling compared with only 5.4% when the lens was absent. Lid derived oxygen acts to provide the ocular surface in the non-contact lens wearing, normally blinking, open-eye with up to 4.7% equivalent oxygen concentration, even within the anoxic environment of a nitrogen filled goggle. Correcting for lid derived oxygen eliminates previously observed discrepancies in corneal swelling behavior and harmonizes the models for the contact lens wearing and gas-goggle cases. On this basis it is proposed that true anoxia at the ocular surface cannot be achieved by atmospheric manipulation (i.e. a gas-goggle) alone but requires an additional presence, e.g. a low, oxygen transmissibility contact lens, to prevent access to oxygen from the eyelids. Data from previously conducted experiments in which the gas-goggle paradigm was used, may have been founded on underestimates of the real oxygen concentration acting on the ocular surface at the time and if so, will require re-interpretation. Future work in this area should consider if a correction for lid derived oxygen is necessary. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rose-K versus Soper contact lens in keratoconus: a randomized comparative trial.

PubMed

Gupta, Raghav; Sinha, Rajesh; Singh, Pooja; Sharma, Namrata; Tandon, Radhika; Titiyal, Jeewan S

2014-01-01

To perform a comparative evaluation of the efficacy and acceptability of Rose-K and Soper contact lenses in Keratoconus. Dr. Rajendra Prasad Center for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi. A randomized comparative clinical trial was performed in keratoconic eyes fitted with Rose-K (Rose-K group) and Soper (Soper group) contact lenses. Patients data were evaluated for best spectacle corrected visual acuity, best contact lens corrected visual acuity (BCLCVA), corneal topography, glare acuity, contrast sensitivity, tear function tests and specular microscopy. Patients were also asked to complete a self-reported comfort questionnaire at each visit. Sixty eyes were randomized to the Rose-K and Soper groups. The two groups were comparable in all the baseline parameters. There was a statistically significant improvement in BCLCVA in both groups at 3 months (P < 0.01, both groups). The difference between in BCLCVA in both groups was not statistically significant. In both groups, there was a significant improvement in the comfort score at 3 months compared to baseline (P < 0.05, both group). The Rose-K group had statistically significantly better scores at 1 and 3 months compared with the Soper group (P = 0.006 and P < 0.001 respectively). Both groups were associated with a significant (P < 0.01), but comparable improvement in glare acuity at 3 months. There was a significant improvement in contrast sensitivity at 3 months in both groups (P < 0.01); the Rose-K group was significantly better than the Soper group at 1 and 3 months (P = 0.001 and 0.002 respectively). The mean number of trial lenses required for fitting Rose-K lens (2.00 ± 0.59) was significantly lower than the Soper lens (3.43 ± 0.82; P < 0.001). Both the contact lens designs provide an equal improvement in visual acuity in patients with Keratoconus. However, Rose-K contact lens provides greater comfort, better quality of vision and requires less chair time compared with the Soper lens and hence may possibly have a greater acceptability.

Water Exposure is a Common Risk Behavior Among Soft and Gas-Permeable Contact Lens Wearers

PubMed Central

Richdale, Kathryn; Mitchell, Gladys Lynn; Kinoshita, Beth T.; Lam, Dawn Y.; Wagner, Heidi; Sorbara, Luigina; Chalmers, Robin L.; Collier, Sarah A.; Cope, Jennifer R.; Rao, Maya M.; Beach, Michael J.; Yoder, Jonathan S.

2017-01-01

Purpose: To understand soft contact lens (SCL) and gas-permeable (GP) lens wearers' behaviors and knowledge regarding exposure of lenses to water. Methods: The Contact Lens Risk Survey (CLRS) and health behavior questions were completed online by a convenience sample of 1056 SCL and 85 GP lens wearers aged 20 to 76 years. Participants were asked about exposing their lenses to water and their understanding of risks associated with these behaviors. Chi-square analyses examined relationships between patient behaviors and perceptions. Results: GP lens wearers were more likely than SCL wearers to ever rinse or store lenses in water (rinsing: 91% GP, 31% SCL, P < 0.001; storing: 33% GP, 15% SCL P < 0.001). Among SCL wearers, men were more likely to store (24% vs. 13%, P = 0.003) or rinse (41% vs. 29%, P = 0.012) their lenses in water. Showering while wearing lenses was more common in SCL wearers (86%) than GP lens wearers (67%) (P < 0.0001). Swimming while wearing lenses was reported by 62% of SCL wearers and 48% of GP lens wearers (P = 0.027). Wearers who rinsed (SCL; P < 0.0001, GP; P = 0.11) or stored lenses in water (SCL; P < 0.0001, GP P = 0.007) reported that this behavior had little or no effect on their infection risk, compared with those who did not. Both SCL (P < 0.0001) and GP lens wearers (P < 0.0001) perceived that distilled water was safer than tap water for storing or rinsing lenses. Conclusions: Despite previously published evidence of Acanthamoeba keratitis' association with water exposure, most SCL, and nearly all GP lens wearers, regularly expose their lenses to water, with many unaware of the risk. PMID:28410356

Water Exposure is a Common Risk Behavior Among Soft and Gas-Permeable Contact Lens Wearers.

PubMed

Zimmerman, Aaron B; Richdale, Kathryn; Mitchell, Gladys Lynn; Kinoshita, Beth T; Lam, Dawn Y; Wagner, Heidi; Sorbara, Luigina; Chalmers, Robin L; Collier, Sarah A; Cope, Jennifer R; Rao, Maya M; Beach, Michael J; Yoder, Jonathan S

2017-08-01

To understand soft contact lens (SCL) and gas-permeable (GP) lens wearers' behaviors and knowledge regarding exposure of lenses to water. The Contact Lens Risk Survey (CLRS) and health behavior questions were completed online by a convenience sample of 1056 SCL and 85 GP lens wearers aged 20 to 76 years. Participants were asked about exposing their lenses to water and their understanding of risks associated with these behaviors. Chi-square analyses examined relationships between patient behaviors and perceptions. GP lens wearers were more likely than SCL wearers to ever rinse or store lenses in water (rinsing: 91% GP, 31% SCL, P < 0.001; storing: 33% GP, 15% SCL P < 0.001). Among SCL wearers, men were more likely to store (24% vs. 13%, P = 0.003) or rinse (41% vs. 29%, P = 0.012) their lenses in water. Showering while wearing lenses was more common in SCL wearers (86%) than GP lens wearers (67%) (P < 0.0001). Swimming while wearing lenses was reported by 62% of SCL wearers and 48% of GP lens wearers (P = 0.027). Wearers who rinsed (SCL; P < 0.0001, GP; P = 0.11) or stored lenses in water (SCL; P < 0.0001, GP P = 0.007) reported that this behavior had little or no effect on their infection risk, compared with those who did not. Both SCL (P < 0.0001) and GP lens wearers (P < 0.0001) perceived that distilled water was safer than tap water for storing or rinsing lenses. Despite previously published evidence of Acanthamoeba keratitis' association with water exposure, most SCL, and nearly all GP lens wearers, regularly expose their lenses to water, with many unaware of the risk.

Candida albicans and Pseudomonas aeruginosa adhesion on soft contact lenses.

PubMed

Onurdağ, Fatma Kaynak; Ozkan, Semiha; Ozgen, Selda; Olmuş, Hülya; Abbasoğlu, Ufuk

2011-04-01

In this study it was aimed to determine the adherence of Pseudomonas and Candida to contact lens surfaces, and to determine the difference in adherence between five contact lens types. Biofilm-negative control strains were also used to emphasize the difference between biofilm-positive and biofilm-negative strains in adherence. Five different soft contact lenses were used to investigate the adherence of Pseudomonas aeruginosa and Candida albicans strains. P. aeruginosa ATCC 27853, P. aeruginosa ATCC 10145, C.albicans ATCC 10231 standard strains and C. albicans clinical isolate were included in the study. Slime formation was investigated by two methods; modified Christensen macrotube method, and a modified microtiter plate test. P. aeruginosa and C. albicans slime formation on soft contact lenses was studied in adherence and separation phases. Pseudomonas and Candida suspensions were serially diluted and inoculated to blood agar and sabouraud dextrose agar surfaces respectively. After overnight incubation, the colonies were counted. Sterile unworn contact lenses were used as negative controls, and bacterial and fungal culture suspensions were used as positive controls. The experiments were conducted in three parallel series. The number of adherent Pseudomonas was as follows from high to low in polymacon, etafilcon A, hilafilcon, ocufilcon and lotrafilcon contact lenses respectively. However, the number of adherent yeast were determined higher in lotrafilcon and ocufilcon contact lenses, followed by hilafilcon, etafilcon A and polymacon contact lenses. Biofilm-negative Pseudomonas ATCC standard strain and Candida clinical isolate were used to confirm that the number of adherent cells were lower than the biofilm-positive ones. This study demonstrates that in addition to the contact lens properties, the microorganisms themselves and their interactions with the lens material also play an important role in adherence.

Comparison of tear osmolarity and ocular comfort between daily disposable contact lenses: hilafilcon B hydrogel versus narafilcon A silicone hydrogel.

PubMed

Sarac, Ozge; Gurdal, Canan; Bostancı-Ceran, Basak; Can, Izzet

2012-06-01

The aim of this study was to evaluate tear osmolarity and ocular comfort with two different types of hydrogel daily disposable lenses. The right eyes of 15 first-time contact lens users were included in this prospective study. All eyes wore hilafilcon B silicone hydrogel contact lenses for 8 h (group 1). After 1 week without contact lenses, all eyes wore narafilcon A silicone hydrogel contact lenses for 8 h (group 2). Tear osmolarity measurement was performed before and after 4 and 8 h of each contact lens wear. Ocular comfort was assessed after 4 and 8 h of each contact lens wear. In group 1, the mean baseline, 4- and 8-h tear osmolarity values were 293 ± 10.57, 303.00 ± 10.5 mOsm/L (p = 0.023), and 295.0 ± 1.4 mOsm/L (p > 0.05), respectively. In group 2, the mean baseline, 4- and 8-h tear osmolarity values were 294 ± 13.65, 300.9 ± 11.3 mOsm/L (p = 0.007), and 298.80 ± 7.2 mOsm/L (p > 0.05), respectively. In group 1, the mean comfort score was 7.20 ± 0.45 and 8.60 ± 0.45 at 4 and 8 h, respectively (p = 0.038). In group 2, the mean comfort score significantly decreased from 9.80 ± 0.45 to 7.80 ± 0.84 at 4 h (p = 0.039). Both hydrogel and silicone hydrogel daily disposable contact lenses elevated tear osmolarity during 8 h of contact lens wear. The increase in tear osmolarity with both contact lenses was below the cut-off value for dry eye and was not associated with ocular comfort.

Bifocal liquid lens zoom objective for mobile phone applications

NASA Astrophysics Data System (ADS)

Wippermann, F. C.; Schreiber, P.; Bräuer, A.; Craen, P.

2007-02-01

Miniaturized camera systems are an integral part of today's mobile phones which recently possess auto focus functionality. Commercially available solutions without moving parts have been developed using the electrowetting technology. Here, the contact angle of a drop of a conductive or polar liquid placed on an insulating substrate can be influenced by an electric field. Besides the compensation of the axial image shift due to different object distances, mobile phones with zoom functionality are desired as a next evolutionary step. In classical mechanically compensated zoom lenses two independently driven actuators combined with precision guides are needed leading to a delicate, space consuming and expansive opto-mechanical setup. Liquid lens technology based on the electrowetting effect gives the opportunity to built adaptive lenses without moving parts thus simplifying the mechanical setup. However, with the recent commercially available liquid lens products a completely motionless and continuously adaptive zoom system with market relevant optical performance is not feasible. This is due to the limited change in optical power the liquid lenses can provide and the dispersion of the used materials. As an intermediate step towards a continuously adjustable and motionless zoom lens we propose a bifocal system sufficient for toggling between two effective focal lengths without any moving parts. The system has its mechanical counterpart in a bifocal zoom lens where only one lens group has to be moved. In a liquid lens bifocal zoom two groups of adaptable liquid lenses are required for adjusting the effective focal length and keeping the image location constant. In order to overcome the difficulties in achromatizing the lens we propose a sequential image acquisition algorithm. Here, the full color image is obtained from a sequence of monochrome images (red, green, blue) leading to a simplified optical setup.

The development of alignment turning system for precision len cells

NASA Astrophysics Data System (ADS)

Huang, Chien-Yao; Ho, Cheng-Fang; Wang, Jung-Hsing; Chung, Chien-Kai; Chen, Jun-Cheng; Chang, Keng-Shou; Kuo, Ching-Hsiang; Hsu, Wei-Yao; Chen, Fong-Zhi

2017-08-01

In general, the drop-in and cell-mounted assembly are used for standard and high performance optical system respectively. The optical performance is limited by the residual centration error and position accuracy of the conventional assembly. Recently, the poker chip assembly with high precision lens barrels that can overcome the limitation of conventional assembly is widely applied to ultra-high performance optical system. ITRC also develops the poker chip assembly solution for high numerical aperture objective lenses and lithography projection lenses. In order to achieve high precision lens cell for poker chip assembly, an alignment turning system (ATS) is developed. The ATS includes measurement, alignment and turning modules. The measurement module including a non-contact displacement sensor and an autocollimator can measure centration errors of the top and the bottom surface of a lens respectively. The alignment module comprising tilt and translation stages can align the optical axis of the lens to the rotating axis of the vertical lathe. The key specifications of the ATS are maximum lens diameter, 400mm, and radial and axial runout of the rotary table < 2 μm. The cutting performances of the ATS are surface roughness Ra < 1 μm, flatness < 2 μm, and parallelism < 5 μm. After measurement, alignment and turning processes on our ATS, the centration error of a lens cell with 200mm in diameter can be controlled in 10 arcsec. This paper also presents the thermal expansion of the hydrostatic rotating table. A poker chip assembly lens cell with three sub-cells is accomplished with average transmission centration error in 12.45 arcsec by fresh technicians. The results show that ATS can achieve high assembly efficiency for precision optical systems.

Vision of low astigmats through thick and thin lathe-cut soft contact lenses.

PubMed

Cho, P; Woo, G C

2001-01-01

Distance and near visual acuity of 13 low astigmats were determined in a double-masked experiment through thick and thin (centre thickness 0.12 mm and 0.06 mm, respectively) spherical lathe-cut soft lenses. For each lens type, distance and near LogMAR VA and over-refraction were assessed with different logMAR VA charts. For 70% of the subjects, the residual astigmatism was significantly lower than the refractive astigmatism with thicker lenses. No statistically significant differences in the distance and near logMAR VA was found between the two lens types using any of the charts used, though, in general, logMAR VA obtained through the thicker lens was better than logMAR VA through the thinner lens. The variabilities in distance and near logMAR VA between the two lens types increased with decreased contrast. The variabilities in distance logMAR VA were greater with Chinese charts than with English charts, and LogMAR VA with Chinese charts were significantly worse for both lens types. Based on the results of this study, we concluded that thicker spherical lathe-cut soft lenses provide better vision in low astigmats. The Snellen acuity test is inadequate for vision assessment of soft contact lens wearers. When a patient wearing thin soft contact lenses complains of poor vision in spite of 6/6 or 6/5 Snellen acuity, changing to thicker lenses may be considered.

Interferometric characterization of tear film dynamics

NASA Astrophysics Data System (ADS)

Primeau, Brian Christopher

The anterior refracting surface of the eye is the thin tear film that forms on the surface of the cornea. When a contact lens is on worn, the tear film covers the contact lens as it would a bare cornea, and is affected by the contact lens material properties. Tear film irregularity can cause both discomfort and vision quality degradation. Under normal conditions, the tear film is less than 10 microns thick and the thickness and topography change in the time between blinks. In order to both better understand the tear film, and to characterize how contact lenses affect tear film behavior, two interferometers were designed and built to separately measure tear film behavior in vitro and in vivo. An in vitro method of characterizing dynamic fluid layers applied to contact lenses mounted on mechanical substrates has been developed using a phase-shifting Twyman-Green interferometer. This interferometer continuously measures light reflected from the surface of the fluid layer, allowing precision analysis of the dynamic fluid layer. Movies showing this fluid layer behavior can be generated. The fluid behavior on the contact lens surface is measured, allowing quantitative analysis beyond what typical contact angle or visual inspection methods provide. The in vivo interferometer is a similar system, with additional modules included to provide capability for human testing. This tear film measurement allows analysis beyond capabilities of typical fluorescein visual inspection or videokeratometry and provides better sensitivity and resolution than shearing interferometry methods.

In vitro and in vivo evaluation of novel ciprofloxacin-releasing silicone hydrogel contact lenses.

PubMed

Hui, Alex; Willcox, Mark; Jones, Lyndon

2014-07-15

The purpose of this study was to evaluate ciprofloxacin-releasing silicone hydrogel contact lens materials in vitro and in vivo for the treatment of microbial keratitis. Model silicone hydrogel contact lens materials were manufactured using a molecular imprinting technique to modify ciprofloxacin release kinetics. Various contact lens properties, including light transmission and surface wettability, were determined, and the in vitro ciprofloxacin release kinetics elucidated using fluorescence spectrophotometry. The materials then were evaluated for their ability to inhibit Pseudomonas aeruginosa growth in vitro and in an in vivo rabbit model of microbial keratitis. Synthesized lenses had similar material properties to commercial contact lens materials. There was a decrease in light transmission in the shorter wavelengths due to incorporation of the antibiotic, but over 80% light transmission between 400 and 700 nm. Modified materials released for more than 8 hours, significantly longer than unmodified controls (P < 0.05). In vivo, there was no statistically significant difference between the number of colony-forming units (CFU) recovered from corneas treated with eye drops and those treated with one of two modified contact lenses (P > 0.05), which is significantly less than corneas treated with unmodified control lenses or those that received no treatment at all (P < 0.05). These novel contact lenses designed for the extended release of ciprofloxacin may be beneficial to supplement or augment future treatments of sight-threatening microbial keratitis. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Dynamics of Flagellum- and Pilus-Mediated Association of Pseudomonas aeruginosa with Contact Lens Surfaces▿

PubMed Central

Tran, Victoria B.; Fleiszig, Suzanne M. J.; Evans, David J.; Radke, Clayton J.

2011-01-01

Flagella and pili are appendages that modulate attachment of Pseudomonas aeruginosa to solid surfaces. However, previous studies have mostly reported absolute attachment. Neither the dynamic roles of these appendages in surface association nor those of attachment phenotypes have been quantified. We used video microscopy to address this issue. Unworn, sterile, soft contact lenses were placed in a laminar-flow optical chamber. Initial lens association kinetics for P. aeruginosa strain PAK were assessed in addition to lens-surface association phenotypes. Comparisons were made to strains with mutations in flagellin (fliC) or pilin (pilA) or those in flagellum (motAB) or pilus (pilU) function. PAK and its mutants associated with the contact lens surface at a constant rate according to first-order kinetics. Nonswimming mutants associated ∼30 to 40 times slower than the wild type. PAK and its pilA mutant associated at similar rates, but each ∼4 times faster than the pilU mutant. Lens attachment by wild-type PAK induced multiple phenotypes (static, lateral, and rotational surface movement), each showing only minor detachment. Flagellin (fliC) and flagellar-motility (motAB) mutants did not exhibit surface rotation. Conversely, strains with mutations in pilin (pilA) and pilus retraction (pilU) lacked lateral-surface movement but displayed enhanced surface rotation. Slower surface association of swimming-incapable P. aeruginosa mutants was ascribed to lower convective-diffusion-arrival rates, not to an inability to adhere. Flagellum function (swimming) enhanced lens association, attachment, and rotation; hyperpiliation hindered lens association. P. aeruginosa bound through three different adhesion sites: flagellum, pili, and body. Reduction of bacterial attachment to contact lenses thus requires blockage of multiple adhesion phenotypes. PMID:21498762

A method for profiling biometric changes during disaccommodation.

PubMed

Alderson, Alison; Davies, Leon N; Mallen, Edward A H; Sheppard, Amy L

2012-05-01

To demonstrate the application of low-coherence reflectometry to the study of biometric changes during disaccommodation responses in human eyes after cessation of a near task and to evaluate the effect of contact lenses on low-coherence reflectometry biometric measurements. Ocular biometric parameters of crystalline lens thickness (LT) and anterior chamber depth (ACD) were measured with the LenStar device during and immediately after a 5 D accommodative task in 10 participants. In a separate trial, accommodation responses were recorded with a Shin-Nippon WAM-5500 optometer in a subset of two participants. Biometric data were interleaved to form a profile of post-task anterior segment changes. In a further experiment, the effect of soft contact lenses on LenStar measurements was evaluated in 15 participants. In 10 adult participants, increased LT and reduced ACD was seen during the 5 D task. Post-task, during fixation of a 0 D target, a profile of the change in LT and ACD against time was observed. In the two participants with accommodation data (one a sufferer of nearwork-induced transient myopia and other a non-sufferer), the post-task changes in refraction compared favorably with the interleaved LenStar biometry data. The insertion of soft contact lenses did not have a significant effect on LenStar measures of ACD or LT (mean change: -0.007 mm, p = 0.265 and + 0.001 mm, p = 0.875, respectively). With the addition of a relatively simple stimulus modification, the LenStar instrument can be used to produce a profile of post-task changes in LT and ACD. The spatial and temporal resolution of the system is sufficient for the investigation of nearwork-induced transient myopia from a biometric viewpoint. LenStar measurements of ACD and LT remain valid after the fitting of soft contact lenses.

Exploring pH-Sensitive Hydrogels Using an Ionic Soft Contact Lens: An Activity Using Common Household Materials

ERIC Educational Resources Information Center

Chen, Yueh-Huey; He, Yu-Chi; Yaung, Jing-Fun

2014-01-01

Hydrogels of the so-called smart polymers or environment-sensitive polymers are important modern biomaterials. Herein, we describe a hands-on activity to explore the pH-responsive characteristics of hydrogels using a commercially available ionic soft contact lens that is a hydrogel of poly(2-hydroxyethyl methacrylate-"co"-methacrylic…

Periscope for noninvasive two-photon imaging of murine retina in vivo

PubMed Central

Stremplewski, Patrycjusz; Komar, Katarzyna; Palczewski, Krzysztof; Wojtkowski, Maciej; Palczewska, Grazyna

2015-01-01

Two-photon microscopy allows visualization of subcellular structures in the living animal retina. In previously reported experiments it was necessary to apply a contact lens to each subject. Extending this technology to larger animals would require fitting a custom contact lens to each animal and cumbersome placement of the living animal head on microscope stage. Here we demonstrate a new device, periscope, for coupling light energy into mouse eye and capturing emitted fluorescence. Using this periscope we obtained images of the RPE and their subcellular organelles, retinosomes, with larger field of view than previously reported. This periscope provides an interface with a commercial microscope, does not require contact lens and its design could be modified to image retina in larger animals. PMID:26417507

Preliminary evaluation of several disinfection/sterilization techniques for use with microdialysis probes.

PubMed

Huff, Jacquelyn K; Bresnahan, James F; Davies, Malonne I

2003-06-06

This study evaluated the suitability of some disinfection and sterilization methods for use with microdialysis probes. Disinfection or sterilization should minimize the tissue inflammatory reaction and improve the long-term health of rats on study and ensure the quality of data obtained by microdialysis sampling. Furthermore, the treatment should not negatively impact probe integrity or sampling performance. The techniques chosen for evaluation included two disinfection methods (70% ethanol and a commercial contact lens solution) and two sterilization methods (hydrogen peroxide plasma, and e-beam radiation). Linear microdialysis probes treated by these processes were compared to untreated probes removed from the manufacturer's packaging as if sterile (the control group). The probes were aseptically implanted in the livers of rats and monitored for 72 hours. The parameters chosen to evaluate probe performance were relative sample mass recovery and the relative in vivo extraction efficiency of the probe for caffeine. Post mortem bacterial counts and histopathology examination of liver tissue were also conducted. The probes remained intact and functional for the entire study period. The methods tested did not acutely alter the probes although hydrogen peroxide plasma and contact lens solution groups showed reduced extraction efficiencies. Minimal tissue damage was observed surrounding the probes and acute inflammatory reaction was mild to moderate. Low numbers of bacterial colonies from the implantation sites indicates that the health of animals in this study was not impaired. This was also true for the control group (untreated probe).

Surface chemical structure for soft contact lenses as a function of polymer processing.

PubMed

Grobe, G L; Valint, P L; Ammon, D M

1996-09-01

The surface chemistry and topography of cast-molded Etafilcon-A and doubled-sided lathed Etafilcon-A soft contact lenses were determined to be significantly different. The variations in surface chemical and morphologic structure between the two lenses were the result of contact lens manufacturing methods. The surface of the cast-molded Etafilcon-A had a consistently less rough surface compared to the doubled sided lathed Etafilcon-A as determined by atomic force microscopy. The surface of the doubled sided lathed Etafilcon-A contained primarily silicone and wax contamination in addition to minute amounts of HEMA. The cast-molded Etafilcon-A had an elemental and chemical content which was consistent with the polymer stoichiometry. Contact angle wettability profiles revealed inherent wettability differences between the two lenses types. The cast-molded Etafilcon-A had an inherently greater water wettability, polarity, and critical surface tension. This means that these two lenses cannot be compared as similar or identical lens materials in terms of surface composition. The manufacturing method used to produce a soft contact lens directly determines the surface elemental and chemical structure as well as the morphology of the finished lens material. These results suggest possible differences in the clinical comfort, spoilage, and lubricity felt during patient wear.

Objective assessment of the effect of pupil size upon the power distribution of multifocal contact lenses.

PubMed

Papadatou, Eleni; Del Águila-Carrasco, Antonio J; Esteve-Taboada, José J; Madrid-Costa, David; Cerviño-Expósito, Alejandro

2017-01-01

To analytically assess the effect of pupil size upon the refractive power distributions of different designs of multifocal contact lenses. Two multifocal contact lenses of center-near design and one multifocal contact lens of center-distance design were used in this study. Their power profiles were measured using the NIMO TR1504 device (LAMBDA-X, Belgium). Based on their power profiles, the power distribution was assessed as a function of pupil size. For the high addition lenses, the resulting refractive power as a function of viewing distance (far, intermediate, and near) and pupil size was also analyzed. The power distribution of the lenses was affected by pupil size differently. One of the lenses showed a significant spread in refractive power distribution, from about -3 D to 0 D. Generally, the power distribution of the lenses expanded as the pupil diameter became greater. The surface of the lens dedicated for each distance varied substantially with the design of the lens. In an experimental basis, our results show how the lenses power distribution is affected by the pupil size and underlined the necessity of careful evaluation of the patient's visual needs and the optical properties of a multifocal contact lens for achieving the optimal visual outcome.

TESS Lens-Bezel Assembly Modal Testing

NASA Technical Reports Server (NTRS)

Dilworth, Brandon J.; Karlicek, Alexandra

2017-01-01

The Transiting Exoplanet Survey Satellite (TESS) program, led by the Kavli Institute for Astrophysics and Space Research at the Massachusetts Institute of Technology (MIT) will be the first-ever spaceborne all-sky transit survey. MIT Lincoln Laboratory is responsible for the cameras, including the lens assemblies, detector assemblies, lens hoods, and camera mounts. TESS is scheduled to be launched in August of 2017 with the primary goal to detect small planets with bright host starts in the solar neighborhood, so that detailed characterizations of the planets and their atmospheres can be performed. The TESS payload consists of four identical cameras and a data handling unit. Each camera consists of a lens assembly with seven optical elements and a detector assembly with four charge-coupled devices (CCDs) including their associated electronics. The optical prescription requires that several of the lenses are in close proximity to a neighboring element. A finite element model (FEM) was developed to estimate the relative deflections between each lens-bezel assembly under launch loads to predict that there are adequate clearances preventing the lenses from making contact. Modal tests using non-contact response measurements were conducted to experimentally estimate the modal parameters of the lens-bezel assembly, and used to validate the initial FEM assumptions. Key Words Non-contact measurements, modal analysis, model validation

Design of a novel system for spectroscopy measurements of the aqueous humor

NASA Astrophysics Data System (ADS)

Miller, Joe; Uttamchandani, Deepak G.

2001-06-01

The authors report on the design of a system which will enable real time measurements of (therapeutic) drug concentrations in the anterior chamber of the eye. Currently the concentration of therapeutic drugs in the anterior chamber is determined by analyzing samples which have been removed from the aqueous humor of laboratory animal eyes. This sampling via paracentesis can be painful and does not provide a continuous measurement. Our system will be far less invasive, removing the need for sampling via paracentesis, and also providing a continuous measurement, enabling a more complete understanding of the kinetics of ophthalmic drugs. A key component in our novel system is a specially constructed contact lens. We report on the design, optimization and manufacture of such a contact lens system capable of directing UV/VIS light in, across and out of the anterior chamber of the eye, thereby enabling absorption spectroscopy measurements of the aqueous humor to be undertaken. Design of the one piece contact lens/mirror system was achieved using the Zemax optical design software package and the lens was fabricated from synthetic fused silica. Results from modeling of the lens and experimental measurements on light propagation across the anterior chamber of animal eyes assisted by the lens will be reported.

Melimine-Coated Antimicrobial Contact Lenses Reduce Microbial Keratitis in an Animal Model.

PubMed

Dutta, Debarun; Vijay, Ajay K; Kumar, Naresh; Willcox, Mark D P

2016-10-01

To determine the ability of antimicrobial peptide melimine-coated contact lenses to reduce the incidence of microbial keratitis (MK) in a rabbit model of contact lens wear. In vitro antimicrobial activity of melimine-coated contact lenses was determined against Pseudomonas aeruginosa by viable count and a radiolabeled assay. The amount of lipopolysaccharide (LPS) associated with bacteria bound to melimine-coated and control lenses was determined. Ocular swabs from rabbit eyes were collected for assessment of ocular microflora. A rabbit model for MK was developed that used overnight wear of contact lenses colonized by P. aeruginosa in the absence of a corneal scratch. During lens wear, detailed ocular examinations were performed, and the incidence of MK was investigated. Bacteria associated with worn lenses and infected corneas were determined by viable plate count. Inhibition in viable and total P. aeruginosa adhesion by melimine-coated contact lenses was 3.1 log10 and 0.4 log10, respectively. After colonization, the amount of LPS on lenses was approximately the same with or without melimine. Gram-positive bacteria were found in all the ocular swabs followed by fungus (42%). Melimine-coated lens wear was protective and significantly (odds ratio 10.12; P = 0.012) reduced the incidence of P. aeruginosa-driven MK in the rabbit model. The antimicrobial lenses were associated with significantly (P < 0.001) lower ocular scores, indicating improved ocular signs compared with controls. This study showed that contaminated contact lenses can produce MK without corneal epithelial defect in an animal model. Melimine-coated contact lenses reduced the incidence of MK associated with P. aeruginosa in vivo. Development of MK requires viable bacteria adherent to contact lenses, and bacterial debris adherent at the lens surface did not cause keratitis.

Oral omega-3 fatty acid treatment for dry eye in contact lens wearers.

PubMed

Bhargava, Rahul; Kumar, Prachi

2015-04-01

The aim of this study was to evaluate the effect of dietary omega-3 fatty acid (O3FA) supplementation on dry eye symptoms, tear film tests, and conjunctival impression cytology in patients with contact lens wear-associated dry eye. In this randomized, double-blind, multicentric trial, contact lens wearers (n = 496) were randomized to receive either O3FAs or placebo capsules (corn oil) twice daily for 6 months. Subjects underwent examinations at baseline, 3 months, and 6 months. At each visit, a questionnaire of dry eye symptoms and lens wear comfort was administered. Subjects further underwent measurement of tear film break-up time (TBUT) and a Schirmer test. Conjunctival impression cytology was performed by the transfer method. Improvement in symptoms and lens wear comfort were primary outcome measures. Changes from baseline in TBUT, Schirmer, and Nelson grade at 6 months were secondary outcome measures. The mean improvement in symptom score in the O3FA group was 4.7 ± 2 (2.0) as compared with 0.5 ± 2 (0.9) in the placebo group (P < 0.0001). Lens wear comfort levels improved significantly (P < 0.0001) from baseline. There was a significant increase in TBUT [3.3 ± 2 (1.5)] and Nelson grade [0.7 ± 2 (0.6)] in the O3FA group (P < 0.0001) as compared with 0.3 ± 2 (0.6) and 0.1 ± 2 (0.4) in the placebo group (P = 0.164 and 0.094, respectively). However, the magnitude of increase in Schirmer score [2.0 ± 2 (1.5)] was relatively small (P = 0.08). The results of this study point toward benefits of orally administered O3FAs in alleviating dry eye symptoms, improving lens wear comfort, and cytological changes in contact lens wearers.

Clinical Evaluation of Large Diameter Rigid-Gas Permeable Versus Soft Toric Contact Lenses for the Correction of Refractive Astigmatism. A MultiCenter Study.

PubMed

Michaud, Langis; Bennett, Edward S; Woo, Stephanie L; Reeder, Renee; Morgan, Bruce W; Dinardo, Amy; Harthan, Jennifer S

2018-05-01

This study aims to address the clinical performance of a large diameter rigid gas permeable lens (LRGP) in a group of subjects with low-to-moderate (0.75-2.75 D) refractive astigmatism. An additional goal was to determine whether soft toric or LRGP contact lenses performed better objectively in the correction of astigmatism and to determine which modality is preferred by subjects. This was a multisite prospective cross-over clinical study. Ten asymptomatic contact lens wearers per site (four university clinics) were recruited and randomly assigned to group A or group B. Group A was assigned to start wearing Comfilcon A soft toric lens first, for two weeks, and then crossed over to LRGP lenses (Boston XO, 14.3 mm diameter miniscleral lens). Group B initially wore LRGP lenses and then crossed over to soft toric lenses. For each type of lens worn, low-contrast and high-contrast visual acuity (VA) were evaluated at distance. At the conclusion of the study, after two months, all subjects completed a questionnaire in which they were asked to indicate their preference for one type of lens (soft toric or LRGP) and to rate the quality of vision in day-to-day activities. Thirty-six of 38 (94.7%) subjects completed the study with 75% preferring the vision of the LRGP lens as compared to the soft toric lenses worn in the study. 52.7% expressed a preference to continue with this modality despite only 38.8% reporting that these LRGP lenses are easy or very easy to handle. Wear time, subjective comfort, and subjective vision ratings exhibited no significant difference between the two groups. In a population of asymptomatic contact lens wearers, LRGP lenses can be considered as a good alternative to soft toric lenses for the correction of refractive astigmatism.

Operational Use Of Contact Lenses By Military Aircrew (L’Utilisation Operationnelle des Lentilles de Contact)

DTIC Science & Technology

1992-10-01

Astigmatism 1 I Accommodation and Convergence 12 Advantages and Disadvantages of Contact Lenses 12 Optical Performance 12 Compliance 13 Supervision 13...absence of parallel tear lens, especially advantages of dealing with only one type of lens and accompanying astigmatism ) support system. - discomfort...Polcon I low. provides an explanation for the failure of high Dk Potycon 1I 8 a materials in fitting a cornea with astigmatism and the Si-02-•• ex need

Fitting an MSD (mini scleral design) rigid contact lens in advanced keratoconus with INTACS.

PubMed

Dalton, Kristine; Sorbara, Luigina

2011-12-01

Keratoconus is a bilateral degenerative disease characterized by a non-inflammatory, progressive central corneal ectasia (typically asymmetric) and decreased vision. In its early stages it may be managed with spectacles and soft contact lenses but more commonly it is managed with rigid contact lenses. In advanced stages, when contact lenses can no longer be fit, have become intolerable, or corneal damage is severe, a penetrating keratoplasty is commonly performed. Alternative surgical techniques, such as the use of intra-stromal corneal ring segments (INTACS) have been developed to try and improve the fit of rigid contact lenses in keratoconic patients and avoid penetrating keratoplasties. This case report follows through the fitting of rigid contact lenses in an advanced keratoconic cornea after an INTACS procedure and discusses clinical findings, treatment options, and the use of mini-scleral and scleral lens designs as they relate to the challenges encountered in managing such a patient. Mini-scleral and scleral lenses are relatively easy to fit, and can be of benefit to many patients, including advanced keratoconic patients, post-INTAC patients and post-penetrating keratoplasty patients. 2011 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Robert Mandell: a pioneer and giant in the art and science of contact lenses.

PubMed

Polse, Kenneth A

2008-10-01

Robert B. Mandell is the quintessential modern clinical scientist. Over his long academic career, he has pioneered many advances in contact lens practice, ranging from a more complete understanding of corneal shape to the effects of contact lenses on corneal health. His classic text, Contact Lens Practice, first published in 1965, was reprinted 14 times in four editions up to 1988. Mandell's contributions to the advancement of the profession of optometry have always been characterized by a genuine concern for the patient and a steadfast belief that his research must have relevance to the practice of optometry.

Bacterial Coaggregation and Cohesion Among Isolates From Contact Lens Cases.

PubMed

Datta, Ananya; Stapleton, Fiona; Willcox, Mark D P

2018-06-01

The aim of this study was to examine cohesion, coaggregation, and coculture between bacteria commonly isolated from contact lens cases. Staphylococcus epidermidis, Staphylococcus haemolyticus, Micrococcus luteus, and Acinetobacter radioresistens (two strains each) isolated from contact lens cases of two asymptomatic wearers were used in this study. In the cohesion assay, bacteria were grown, washed, and examined by incubating lens cases with two different types of bacteria sequentially and assessing the number of adhered cells of each isolate. The ability of isolates to interfere with the growth of other isolates was tested by growing strains in cocultures for 24 hours and determining the numbers of cells of individual strains. For coaggregation, equal proportions of two bacterial suspensions were mixed and allowed to coaggregate for 24 hours. Inhibition of coaggregation was tested by the addition of lactose (0.06 M) or sucrose (0.06 M) or pronase. The initial adhesion of M. luteus or A. radioresistens significantly (P < 0.05) enhanced the subsequent adhesion of the staphylococci. The addition of A. radioresistens in liquid media significantly (P < 0.05) enhanced the growth of staphylococci. S. epidermidis or S. haemolyticus coaggregated with M. luteus or A. radioresistens. The degree of coaggregation varied between 30% and 54%. The highest coaggregation (54% ± 5%) was seen between A. radioresistens 22-1 and S. epidermidis 22-1, isolated from the same lens case. Only lactose or sucrose treatment of staphylococci could partly inhibit coaggregation of some pairs. Coaggregation, cohesion, and growth promotion may facilitate the process of bacterial colonization of contact lens cases.

Rat silicone hydrogel contact lens model: effects of high- versus low-Dk lens wear.

PubMed

Zhang, Yunfan; Gabriel, Manal M; Mowrey-McKee, Mary F; Barrett, Ronald P; McClellan, Sharon; Hazlett, Linda D

2008-11-01

This study used a rat contact lens (CL) model to test if high- versus low-Dk lens wear caused changes in (1) conjunctival Langerhans cell (LC) number or location; (2) Bcl-2 expression; and (3) infection risk. Female, Lewis rats wore a high- or low-Dk CL continuously for 2 weeks. Afterward, corneas were harvested and processed for ADPase activity to identify LCs, for immunostaining and for real time-polymerase chain reaction. Contact lens-wearing rats also were challenged with Pseudomonas aeruginosa by placing a bacterial-soaked CL on the eye followed by topical delivery of bacteria. After 48 hrs, slit lamp examination and real time-polymerase chain reaction were used to evaluate the corneal response. Conjunctival LC were significantly increased after low- versus high-Dk CL wear (P<0.0001). In contrast, conjunctival LC in non-lens wearing rats was not significantly different from the high-Dk lens wearing group. Bcl-2 mRNA levels were significantly decreased in low- versus high-Dk CL wearing rats, while Bax, FasL, caspase 3, and caspase 9 levels were unchanged. Immunostaining for Bcl-2 showed fewer positively stained epithelial cells in the low- versus high-Dk lens wearing group. After bacterial challenge, 30% of low- versus none of the high-Dk CL wearing corneas became infected and showed increased mRNA levels for several proinflammatory cytokines/chemokines, inducible nitric oxide synthase and matrix metalloproteinase-9. Low- versus high-Dk or non-CL wear led to an increased number of conjunctival LC, decreased Bcl-2 levels, and increased the risk of bacterial infection.

Polydimethylsiloxane as dielectric and hydrophobic material in electro-wetting liquid lens

NASA Astrophysics Data System (ADS)

Wang, Liang; Duan, Junping; Zhang, Binzhen; Wang, Wanjun

2016-10-01

An electro-wetting-based variable-focus liquid lens with a spin coated polydimethylsiloxane (PDMS) layer is presented. The PDMS layer acts as both insulation and hydrophobic material of the liquid lens. By changing the applied voltage between the two electrodes, the radius of the water-oil contact curved surface is adjusted to realize the zoom function. In preparation process, at first, the liquid lens is divided into two parts, the PDMS substrate and the cavity, and then two parts of liquid lens are bonding together after surface treatment. After liquid injection and sealing cavity, the whole process was accomplished. The zooming performance of lens is tested, and COMSOL is used to analyze the shape of the water-oil contact curved surface at different voltages, the results shows that with the applied voltage changing from 0V to 120V, the height of meniscus vertex reduced from 2.41mm to 1.67mm, and the focal length changes from -14.3mm to infinity first, and then to 27.1mm.

Analytical Solution for Interface Flow to a Sink With an Upconed Saline Water Lens: Strack's Regimes Revisited

NASA Astrophysics Data System (ADS)

Kacimov, A. R.; Obnosov, Y. V.

2018-01-01

A study is made of a steady, two-dimensional groundwater flow with a horizontal well (drain), which pumps out freshwater from an aquifer sandwiched between a horizontal bedrock and ponded soil surface, and containing a lens-shaped static volume of a heavier saline water (DNAPL-dense nonaqueous phase liquid) as a free surface. For flow toward a line sink, an explicit analytical solution is obtained by a conformal mapping of the hexagon in the complex potential plane onto a reference plane and the Keldysh-Sedov integral representation of a mixed boundary-value problem for a complex physical coordinate. The interface is found as a function of the pumping rate, the well locus, the ratio of liquid densities, and the hydraulic heads at the soil surface and in the well. The shape with two inflexion points and fronts varies from a small-thickness bedrock-spread pancake to a critical curvilinear triangle, which cusps toward the sink. The problem is mathematically solvable in a relatively narrow band of geometric and hydraulic parameters. A similar analytic solution for a static heavy bubble confined by a closed-curve interface (no contact with the bedrock) is outlined as an illustration of the method to solve a mixed boundary-value problem.

Scedosporium prolificans Keratouveitis in Association with a Contact Lens Retained Intraocularly over a Long Term

PubMed Central

Arthur, Stella; Steed, Lisa L.; Apple, David J.; Peng, Qun; Howard, Gene; Escobar-Gomez, Marcela

2001-01-01

Scedosporium prolificans is a soil saprophyte that is associated with a large variety of infectious processes and with respiratory colonization in immunocompetent and immunocompromised patients. We report the first described case of S. prolificans keratouveitis associated with the intraocular long-term retention of a contact lens in a 76-year-old female patient. PMID:11724890

Simulation Study of an Ultrasound Retinal Prosthesis With a Novel Contact-Lens Array for Noninvasive Retinal Stimulation.

PubMed

Gao, Mengdi; Yu, Yanyan; Zhao, Huixia; Li, Guofeng; Jiang, Hongyang; Wang, Congzhi; Cai, Feiyan; Chan, Leanne Lai-Hang; Chiu, Bernard; Qian, Wei; Qiu, Weibao; Zheng, Hairong

2017-09-01

Millions of people around the world suffer from varying degrees of vision loss (including complete blindness) because of retinal degenerative diseases. Artificial retinal prosthesis, which is usually based on electrical neurostimulation, is the most advanced technology for different types of retinal degeneration. However, this technology involves placing a device into the eyeball, and such a highly invasive procedure is inevitably highly risk and expensive. Ultrasound has been demonstrated to be a promising technology for noninvasive neurostimulation, making it possible to stimulate the retina and induce action potentials similar to those elicited by light stimulation. However, the technology of ultrasound retinal stimulation still requires considerable developments before it could be applied clinically. This paper proposes a novel contact-lens array transducer for use in an ultrasound retinal prosthesis (USRP). The transducer was designed in the shape of a contact lens so as to facilitate acoustic coupling with the eye liquid. The key parameters of the ultrasound transducer were simulated, and results are presented that indicate the achievement of 2-D pattern generation and that the proposed contact-lens array is suitable for multiple-focus neurostimulation, and can be used in a USRP.

Risk factors for interruption to soft contact lens wear in children and young adults.

PubMed

Wagner, Heidi; Chalmers, Robin L; Mitchell, G Lynn; Jansen, Meredith E; Kinoshita, Beth T; Lam, Dawn Y; McMahon, Timothy T; Richdale, Kathryn; Sorbara, Luigina

2011-08-01

The purpose of this study was to describe age and other risk factors for ocular events that interrupt soft contact lens (SCL) wear in youth. A retrospective chart review of SCL wearers aged 8 to 33 years at the first observed visit was conducted at six academic eye care centers in North America. Data were extracted from all visits during the observation period (>3 years). Clinical records that documented conditions resulting in an interruption of SCL wear "events" were scanned, masked for age and SCL parameters, and then adjudicated to consensus diagnosis. Generalized estimating equations were used to examine the effect of selected covariates, including age, on the risk of an event. Chart review of 3549 SCL wearers yielded 522 events among 426 wearers (12%). The risk of an event increased from ages 8 to 18 years, showed modest increases between ages 19 and 25 years, and then began to decline after age 25 years. New lens wearers (<1 year) were less likely to experience events (p = 0.001). Lens replacement schedule and material were also predictive of interruptions to SCL wear with the lowest risk in daily replacement and hydrogel lens wearers (both p < 0.0001). These results suggest that the risk of events that interrupt SCL wear peaks in late adolescence and early adulthood and reflects risk factors identified in prospective contact lens studies. Relative to older teens and young adults, patients younger than 14 years presented with significantly fewer events resulting in interrupted lens wear.

[Profile of medical students from the Universidade Estadual Paulista-UNESP--Botucatu, who wear contact lenses].

PubMed

Vidotti, Vanessa Gonçalves; Kamegasawa, Amélia

2006-01-01

To analyze the ametropy, way of acquisition, the care and complications related to contact lens wear among medical students from Faculdade de Medicina de Botucatu da Universidade Estadual Paulista-UNESP--Botucatu (SP). Questionnaire applied to students from the 1st to the 6th year of the Medical school of the Faculdade de Medicina de Botucatu da Universidade Estadual Paulista-UNESP--Botucatu (SP), forming an analytical cross-sectional survey. 27.4% of the students use contact lenses, and among them 94.8% use soft contact lenses and 98% have negative degree. 46.9% discard their contact lens monthly. 63.9% have an average daily use of 14 hours, 14.1% acquire the contact lenses from optician stores or at pharmacies and 46.5% of the students clean their contact lenses when they put them on and take them off. Regarding complications, 51.0% reported ocular redness; 44.5%, blurred vision; and 42.6%, foreign body sensation, whereas only 4 students reported "keratitis". We concluded that the inadequate adaptation that occurs even in users knowledgeable about this issue such as medical students, has increased the risk of complications. This fact indicates that more attention must be paid to contact lens care in order to prevent permanent visual deficit.

A Wirelessly Powered Smart Contact Lens with Reconfigurable Wide Range and Tunable Sensitivity Sensor Readout Circuitry

PubMed Central

Chiou, Jin-Chern; Hsu, Shun-Hsi; Huang, Yu-Chieh; Yeh, Guan-Ting; Liou, Wei-Ting; Kuei, Cheng-Kai

2017-01-01

This study presented a wireless smart contact lens system that was composed of a reconfigurable capacitive sensor interface circuitry and wirelessly powered radio-frequency identification (RFID) addressable system for sensor control and data communication. In order to improve compliance and reduce user discomfort, a capacitive sensor was embedded on a soft contact lens of 200 μm thickness using commercially available bio-compatible lens material and a standard manufacturing process. The results indicated that the reconfigurable sensor interface achieved sensitivity and baseline tuning up to 120 pF while consuming only 110 μW power. The range and sensitivity tuning of the readout circuitry ensured a reliable operation with respect to sensor fabrication variations and independent calibration of the sensor baseline for individuals. The on-chip voltage scaling allowed the further extension of the detection range and prevented the implementation of large on-chip elements. The on-lens system enabled the detection of capacitive variation caused by pressure changes in the range of 2.25 to 30 mmHg and hydration level variation from a distance of 1 cm using incident power from an RFID reader at 26.5 dBm. PMID:28067859

Failure of chemotherapy in the first reported cases of Acanthamoeba keratitis in Pakistan

PubMed Central

Siddiqui, Ruqaiyyah; Chaudhry, Tanveer; Lakhundi, Sahreena; Ahmad, Khabir; Khan, Naveed Ahmed

2014-01-01

Acanthamoeba keratitis is a painful and progressive infection of the cornea that can result in loss of vision. Here, for the first time in Pakistan, we report two cases of Acanthamoeba keratitis. The first patient was a 37-year-old female who presented with severe itching, redness, pain, along with loss of vision. The patient was a regular soft contact lens wearer. The second patient was a 25-year-old female who had been using soft contact lenses for the past two years. She presented with a burning sensation and extreme pain, along with loss of vision. Both patients were treated for a possible microbial keratitis with topical moxifloxacin hydrochloride drops, vancomycin drops, propamidine isethionate ointment, amphotericin B drops, and amikacin drops. However, the response was inadequate and both patients were referred for corneal transplant. Acanthamoeba castellanii was isolated by placing contact lenses and contact lens cases on non-nutrient agar plates containing a lawn of non-invasive Escherichia coli K-12 HB101 bacteria. The polymerase chain reaction (PCR) using genus-specific probes confirmed the identity of Acanthamoeba spp., whereas the morphological characteristics of trophozoites and cysts were suggestive of A. castellanii in both cases. With growing use of contact lenses for vision correction/cosmetic use coupled with sub-standard lens care in this region and the possibility of non-contact lens-associated Acanthamoeba keratitis, a need for increased awareness of this sight-threatening infection is discussed further. PMID:24548160

Superior limbic keratoconjunctivitis associated with cosmetic soft contact lens wear.

PubMed

Fuerst, D J; Sugar, J; Worobec, S

1983-08-01

Thirteen patients who wore soft contact lenses were seen with a syndrome consistent with superior limbic keratoconjunctivitis. An irregular epithelial surface, punctate staining with fluorescein, and subepithelial infiltrates were found on the superior aspect of the corneas in association with hyperemia of the superior bulbar conjunctivae. The keratoconjunctivitis persisted as long as 15 months after discontinuation of lens wear. Patch testing with ophthalmic vehicle preservatives, performed on seven patients, failed to show a consistent hypersensitivity to any of the tested compounds, and three patients had used only preservative-free saline for lens care. The etiology of this syndrome is unknown.

The influence of lens power and center thickness on the intraocular pressure measured through soft lenses: a comparison of two noncontact tonometers.

PubMed

Ogbuehi, Kelechi C

2012-06-01

To quantify the influence of soft contact lens power and thickness on the intraocular pressure (IOP). Thirty-nine young, healthy adult volunteers completed this study. One eye of each subject was randomly assigned either a +6D or a -6D high water content daily disposable lens. The other eye was fitted with the second lens. Triplicate measurements of IOP were taken before, during, and after contact lens wear. Each time, IOP was assessed in a randomized order with two noncontact tonometers. The lenses were swapped between eyes during a second session of measurements, one week later. In the first session with the +6D lenses, the average IOPs (±SDs) before, with the lenses fitted, and after the lenses were removed, were: 14.3 ± 2.9 mmHg, 17.0 ± 3.3 mmHg and 13.9 ± 3.1 mmHg, respectively, for the CT80 and 13.6 ± 3.1 mmHg, 17.1 ± 4.5 mmHg and 13.3 ± 2.9 mmHg, respectively, for the PT100. The corresponding values for the first session with the -6D lenses were: 14.3 ± 3.1 mmHg, 13.1 ± 3.1 mmHg and 14.1 ± 3.3 mmHg, respectively, for the CT80 and 13.6 ± 3.2 mmHg, 13.0 ± 3.0 mmHg and 13.6 ± 3.2 mmHg, respectively, for the PT100. IOP significantly (P<0.05) increased (+ΔIOP=2.7 ± 0.4 mmHg with the CT80 in the first session) with the +6D lenses, but decreased (P<0.05) when the -6D lenses were fitted (-ΔIOP=0.6 ± 0.2 mmHg with the PT100 in the first session). The soft contact lens-induced changes were consistent between sessions but varied between tonometers. The measurement of IOP through soft contact lenses resulted in consistent, statistically significant differences in IOP, which were not uniform across tonometers and which did not appear to be solely related to the central thickness of the soft contact lenses. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Contact-lens type of micromachined hydrogenated amorphous Si fluorescence detector coupled with microfluidic electrophoresis devices

NASA Astrophysics Data System (ADS)

Kamei, Toshihiro; Wada, Takehito

2006-09-01

A 5.8-μm-thick SiO2/Ta2O5 multilayer optical interference filter was monolithically integrated and micromachined on a hydrogenated amorphous Si (a-Si :H) pin photodiode to form a fluorescence detector. A microfluidic electrophoresis device was mounted on a detection platform comprising a fluorescence-collecting half-ball lens and the micromachined fluorescence detector. The central aperture of the fluorescence detector allows semiconductor laser light to pass up through the detector and to irradiate an electrophoretic separation channel. The limit of detection is as low as 7nM of the fluorescein solution, and high-speed DNA fragment sizing can be achieved with high separation efficiency. The micromachined a-Si :H fluorescence detector exhibits high sensitivity for practical fluorescent labeling dyes as well as integration flexibility on various substances, making it ideal for application to portable microfluidic bioanalysis devices.

Bacterial populations on silicone hydrogel and hydrogel contact lenses after swimming in a chlorinated pool.

PubMed

Choo, Jennifer; Vuu, Kathy; Bergenske, Peter; Burnham, Kara; Smythe, Jennifer; Caroline, Patrick

2005-02-01

A number of reports have indicated an association between swimming with contact lenses and subsequent eye infection. This study tests whether a hydrophilic contact lens worn while swimming accumulates bacteria present in the water. It was of interest to determine whether lens type (silicone hydrogel vs. hydrogel) affected the result. Fifteen healthy noncontact lens wearers swam for 30 minutes with a silicone hydrogel lens (PureVision, Bausch & Lomb, Rochester, NY) on one eye and a hydrogel lens (Acuvue 2, Vistakon Inc., Jacksonville, FL) on the other. Lenses were removed aseptically and placed in sterile vials 10 minutes after the subjects left the water. Microbial growth was enumerated for total numbers of colonies and categorized by species present. Numbers of colonies were compared between the two lens groups and with a water sample taken from the pool at the time of the experiment. Eight of the subjects returned on a different day and wore new lenses for 50 minutes in normal room conditions. Two lenses were lost while swimming. Twenty-seven of the remaining 28 lenses worn while swimming showed colonization, principally with Staphylococcus epidermidis, which was also by far the most common species identified from the water itself. Small numbers of Staphylococcus aureus and Streptococcus salivarius were also present in the water and on the lenses. Numbers of colonies varied among subjects (range, 0 to 230), but no differences were observed between the two lens groups. Lenses removed after 30 minutes of wear without swimming were mostly sterile, with 3 of 16 lenses showing just two colonies each. It appears that wearing a hydrophilic lens while swimming allows accumulation of microbial organisms on or in the lens, regardless of lens material. Swimmers should be advised to wear tight-fitting goggles if lenses are worn while swimming, and thorough disinfection of the lenses before overnight wear seems prudent.

Electrophoresis of tear proteins as a new diagnostic tool for two high risk groups for dry eye: computer users and contact lens wearers.

PubMed

Chiva, Andreea

2011-08-15

Dry eye is the most prevalent condition seen by the ophthalmologist, in particular in elderly. The identification of new common risk factors (computer use and contact lens wear) extends the disease among the young people. The early diagnosis of dry eye is essential, but difficult, because the biochemical changes in tear film usually occur before any detectable signs. Due its advantages, electrophoresis of tear proteins could be an important tool for diagnosis of tear film impairment in high risk groups for dry eye. The role of tear proteins electrophoresis in early diagnosis of dry eye related to computer use and contact lens wear, as well as the biochemical changes in these high risk groups are presented. This review will summarize the actual data concerning the electrophoretic changes of tear proteins in computer users and contact lens wearers, two common high risk groups for dry eye. Electrophoresis of tear proteins using automated system Hyrys-Hydrasys SEBIA France is an important tool for early diagnosis of tear film alterations and monitoring of therapy. The quantification of many proteins in a single analysis using a small quantity of unconcentrated reflex tears is the main advantage of this technique. Electrophoresis of tear proteins should became a prerequisite, in particular for computer users less than 3 h/day, as well as at prescribing contact lenses.

Longitudinal changes in Langerhans cell density of the cornea and conjunctiva in contact lens-induced dry eye.

PubMed

Alzahrani, Yahya; Colorado, Luisa H; Pritchard, Nicola; Efron, Nathan

2017-01-01

The aim was to determine longitudinal changes in Langerhans cell density (LCD) in the human cornea and conjunctiva during asymptomatic and symptomatic contact lens wear. Twenty-five participants with contact lens-induced dry eye (CLIDE) and 35 without CLIDE (NO-CLIDE), diagnosed using a range of symptom questionnaires and objective tests (tear film break up, cotton thread tear test and corneal staining) were enrolled. The central cornea and nasal bulbar conjunctiva were examined using a Heidelberg laser scanning confocal microscope at baseline and following one, four and 24 weeks wear of daily disposable hydrogel contact lenses. Twenty-three non-contact lens-wearing controls were also examined. Langerhans cells were counted manually from randomly selected images. In the cornea, mean and standard error of the mean LCD was greater after one week of lens wear in CLIDE (55 ± 7 cells/mm 2 ) versus NO-CLIDE (43 ± 4 cells/mm 2 ) (p = 0.041) and controls (27 ± 4 cells/mm 2 ) (p < 0.001). LCD was also greater in NO-CLIDE versus controls (p = 0.010). At week 4, LCD was greater in CLIDE (41 ± 6 cells/mm 2 ) versus controls (27 ± 4 cells/mm 2 ) (p = 0.004). There were no other significant differences between groups at weeks four or 24. In the conjunctiva, LCD was greater after one week of lens wear in CLIDE (17 ± 1 cells/mm 2 ) (p = 0.003) and NO-CLIDE (17 ± 3 cells/mm 2 ) (p = 0.001) versus controls (7 ± 1 cells/mm 2 ). There were no significant differences between groups at weeks four or 24. The initial transient increase in corneal and conjunctival LCD in CLIDE (versus NO-CLIDE) suggests an inflammatory component in the aetiology of this condition. © 2016 Optometry Australia.

The influence of rigid gas permeable lens wear on the concentrations of dinucleotides in tears and the effect on dry eye signs and symptoms in keratoconus.

PubMed

Carracedo, Gonzalo; González-Méijome, José Manuel; Martín-Gil, Alba; Carballo, Jesús; Pintor, Jesús

2016-10-01

To evaluate the signs and symptoms of dry eye and dinucleotide secretion in tears of keratoconus patients (KC) and the potential effect of rigid gas permeable (RGP) contact lens wear. Twenty-three KC patients and forty control subjects were enrolled in this study. Signs of dry eye including tear volume, tear stability and corneal staining along with symptoms were assessed using the McMonnies questionnaire. Tears were collected using Schirmer strips, and dinucleotide concentrations in collected tears measured using high pressure liquid chromatography. Values obtained in KC and controls were compared. The effect of contact lens wear in KC was also assessed. KC eyes showed a significantly lower tear volume compared to controls, shorter tear break up time (TBUT), higher corneal staining and higher McMonnies dry eye questionnaire scores (p<0.05). When compared with non-wearers, KC contact lens wearers showed significantly higher symptoms, lower Schirmer and TBUT values (p<0.05). Concentration of Ap4A (0.695±0.304μM vs. 0.185±0.178μM) and Ap5A (0.132±0.128μM vs. 0.045±0.036μM) were higher in KC compared to controls (p<0.001) and only Ap4A was statistically higher in RGP wearers compared to non-wearers (0.794±0.478μM vs. 0.417±0.313μM) (p<0.05). Signs and symptoms of dry eye as well as concentrations of Ap4A and Ap5A were markedly increased in KC patients compared to controls. Moreover, Ap4A and symptoms of dry eye were statistically higher in RGP wearers compared to non-wearers. This seems to indicate that factors such as RGP contact lens wear might exacerbate the clinical condition of dry eye. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Aeromedical implications of the X-Chrom lens for improving color vision deficiencies.

DOT National Transportation Integrated Search

1978-04-01

The X-Chrom contact lens is a recent device recommended to improve defective color vision. The red lens is usually worn on the nondominant eye and may require extended wearing for optimum color vision enhancement. A battery of tests was given to 24 i...

Noninvasive Continuous Monitoring of Tear Glucose Using Glucose-Sensing Contact Lenses.

PubMed

Ascaso, Francisco J; Huerva, Valentín

2016-04-01

: The incidence of diabetes mellitus is dramatically increasing in the developed countries. Tight control of blood glucose concentration is crucial to diabetic patients to prevent microvascular complications. Self-monitoring of blood glucose is widely used for controlling blood glucose levels and usually performed by an invasive test using a portable glucometer. Many technologies have been developed over the past decades with the purpose of obtaining a continuous physiological glycemic monitoring. A contact lens is the ideal vehicle for continuous tear glucose monitoring of glucose concentration in tear film. There are several research groups that are working in the development of contact lenses with embedded biosensors for continuously and noninvasively monitoring tear glucose levels. Although numerous aspects must be improved, contact lens technology is one step closer to helping diabetic subjects better manage their condition, and these contact lenses will be able to measure the level of glucose in the wearer's tears and communicate the information to a mobile phone or computer. This article reviews studies on ocular glucose and its monitoring methods as well as the attempts to continuously monitor the concentration of tear glucose by using contact lens-based sensors.

Ultraviolet radiation-blocking characteristics of contact lenses: relevance to eye protection for psoralen-sensitised patients.

PubMed

Anstey, A; Taylor, D; Chalmers, I; Ansari, E

1999-10-01

Nine brands of contact lens marketed as "UV protective" were tested for ultraviolet (UV) transmission in order to assess potential suitability for psoralen-sensitised patients. UV-transmission characteristics of hydrated lenses was tested with a Bentham monochromator spectro-radiometer system. All lenses showed minimal transmission loss in the visible band. The performance of the nine lenses was uniform for ultraviolet B radiation with negligible transmission, but showed variation in transmission for ultraviolet A radiation. None of the lenses complied with UV-transmission criteria used previously to assess UV-blocking spectacles. Only two lenses had UV-blocking characteristics which came close to the arbitrary criteria used. The performance of ordinary soft and hard lenses was very similar, with negligible blocking of UV radiation. None of the nine contact lenses marketed as "UV protective" excluded sufficient UVA to comply with criteria in current use to assess UV protection in spectacles for psoralen-sensitised patients. However, the improved UV-blocking characteristics of contact lenses identified in this paper compared to previous studies suggests that such a contact lens will soon become available. Meanwhile, contact lens-wearing systemically sensitised PUVA patients should continue to wear approved spectacles for eye protection whilst photosensitised with psoralen.

On-eye optical quality of daily disposable contact lenses for different wearing times.

PubMed

Montés-Micó, Robert; Belda-Salmerón, Lurdes; Ferrer-Blasco, Teresa; Albarrán-Diego, César; García-Lázaro, Santiago

2013-09-01

To quantify the optical quality of various daily disposable contact lenses in vivo and to ascertain its variation in terms of wearing time by means of objective non-invasive determination of wavefront patterns. The crx1 adaptive-optics system was used to measure the wavefront aberrations in 15 myopic eyes before and at 2-h intervals after contact lens fitting, over a 12-h wearing period. Seven types of contact lenses having different material, water content and lens design were evaluated in this study: Dailies Total1, Dailies AquaComfort Plus, Proclear 1 Day, 1-Day Acuvue TruEye, 1-Day Acuvue moist, SofLens daily disposable and Clariti 1-Day. The aberration data were analysed by fitting Zernike polynomials up to the 5th-order for 3 and 5-mm pupils. The optical quality under each condition and at each point in time was described by means of the Root-Mean-Square (RMS) value of wavefront aberration, Modulation Transfer Function (MTF), Point Spread Function and cut-off spatial frequency. A RMS increase was observed after contact lens fitting as well as over time, both for a 3-mm and a 5-mm pupil. Each type of lens induced a different amount of wavefront aberrations, which vary over time also in a different manner. Dailies Total1 showed the lowest RMS values both at baseline and at the end of the day. In addition, Dailies Total1 provided the best MTF out of all the contact lenses that were assessed. These observations were reflected in higher cut-off spatial frequencies and visual resolution both at baseline and after 12 h of wearing time. Aberrometry makes it possible to analyse accurately and in vivo the optical quality of contact lenses and to assess how lenses having different characteristics - such as material or water content - behave for different wearing times. These variations across contact lenses may result in differences in visual performance. © 2013 The Authors Ophthalmic & Physiological Optics © 2013 The College of Optometrists.

Evaluation of diminished microbial contamination in handling of a novel daily disposable flat pack contact lens.

PubMed

Nomachi, Miya; Sakanishi, Kotaro; Ichijima, Hideji; Cavanagh, H Dwight

2013-05-01

To evaluate the efficacy of a novel daily disposable (DD) flat package in regard to microbial contamination on the anterior and posterior surfaces of a contact lens (CL) during handling of the lens for insertion. Four kinds of commercially available general blister-packed daily disposable contact lenses (DD CLs) as controls and a novel Magic 1-day Menicon Flat Pack as a test lens were used for this in vitro study. Lenses were removed from their packages using fingers coated with fluorescein 3 to 5 μm beads or an approximately 7×10(2) to 2×10(3) colony-forming unit (CFU)/mL Staphylococcus aureus suspension. The transfer of fluorescein beads to the surface of the lenses was then observed by fluorescence microscopy. Microbial contamination on the lenses was observed by light microscopy after a 2-day incubation period; and, the number of colonies isolated from the contaminated lenses was determined after 4 days of incubation. The number of fluorescein beads on the Magic lens was significantly less (p<0.05) than that of the general blister-packed control lenses. Adherence of microbial colonies was observed on both inner and outer surfaces of general blister-packed lenses, whereas no colony formation was found on the inner surface of the Magic lens, and the lowest bacterial adherence was observed for the Magic lens. The data demonstrated that placement of the Magic DD lens onto the eye is accompanied by diminished microbial contamination compared with general blister-packed DD CLs. Eye care professionals; however, should instruct patients to comply with intended use of DD CLs to prevent CL-associated microbial keratitis. In all cases, hand washing is mandated prelens insertion.

Influence of day and night wear on surface properties of silicone hydrogel contact lenses and bacterial adhesion.

PubMed

Vermeltfoort, Pit B J; Rustema-Abbing, Minie; de Vries, Joop; Bruinsma, Gerda M; Busscher, Henk J; van der Linden, Matthijs L; Hooymans, Johanna M M; van der Mei, Henny C

2006-06-01

The aim of this study was to determine the effect of continuous wear on physicochemical surface properties of silicone hydrogel (S-H) lenses and their susceptibility to bacterial adhesion. In this study, volunteers wore 2 pairs of either "lotrafilcon A" or "balafilcon A" S-H contact lenses. The first pair was worn continuously for a week and the second pair for 4 weeks. One lens of each pair was used for surface characterization and the other one for bacterial adhesion experiments. Lens surfaces were characterized by examination of their wettability, roughness, elemental composition, and proteins attached to their surfaces. Adhesion of Staphylococcus aureus 835 and Pseudomonas aeruginosa #3 to a lens was studied using a parallel plate flow chamber. Before use, the lotrafilcon A lens was rougher than the balafilcon A lens and had a lower water contact angle and a higher affinity for S. aureus 835. After wear, both lens types had similar water contact angles, whereas the differences in elemental surface composition decreased as well. S. aureus 835 adhered in higher numbers to worn balafilcon A lenses, whereas the opposite was seen for P. aeruginosa #3. The initial deposition rates of both bacterial strains to lotrafilcon A lenses decreased by wearing and were found to correlate significant (P < 0.001) with the surface roughness of worn lenses. In this study, the differences in surface properties between 2 types of S-H lenses were found to change after 1 week of continuous wear. Generally, bacteria adhered in lower numbers and less tenaciously to worn lenses, except S. aureus 835, adhering in higher numbers to worn balafilcon A lenses.

Peripheral myopization and visual performance with experimental rigid gas permeable and soft contact lens design.

PubMed

Pauné, J; Queiros, A; Quevedo, L; Neves, H; Lopes-Ferreira, D; González-Méijome, J M

2014-12-01

To evaluate the performance of two experimental contact lenses (CL) designed to induce relative peripheral myopic defocus in myopic eyes. Ten right eyes of 10 subjects were fitted with three different CL: a soft experimental lens (ExpSCL), a rigid gas permeable experimental lens (ExpRGP) and a standard RGP lens made of the same material (StdRGP). Central and peripheral refraction was measured using a Grand Seiko open-field autorefractometer across the central 60° of the horizontal visual field. Ocular aberrations were measured with a Hartman-Shack aberrometer, and monocular contrast sensitivity function (CSF) was measured with a VCTS6500 without and with the three contact lenses. Both experimental lenses were able to increase significantly the relative peripheral myopic defocus up to -0.50 D in the nasal field and -1.00 D in the temporal field (p<0.05). The ExpRGP induced a significantly higher myopic defocus in the temporal field compared to the ExpSCL. ExpSCL induced significantly lower levels of Spherical-like HOA than ExpRGP for the 5mm pupil size (p<0.05). Both experimental lenses kept CSF within normal limits without any statistically significant change from baseline (p>0.05). RGP lens design seems to be more effective to induce a significant myopic change in the relative peripheral refractive error. Both lenses preserve a good visual performance. The worsened optical quality observed in ExpRGP was due to an increased coma-like and spherical-like HOA. However, no impact on the visual quality as measured by CSF was observed. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Effect of overnight orthokeratology on conjunctival goblet cells.

PubMed

Carracedo, Gonzalo; Martin-Gil, Alba; Fonseca, Begoña; Pintor, Jesús

2016-08-01

To evaluate the differences between goblet cell density (GCD) and symptomatology after one month of orthokeratology lens wear. A pilot, short-term study was conducted. Twenty-two subjects (29.7±7.0 years old) participated voluntarily in the study. Subjects were divided into two groups: habitual silicone hydrogel contact lens wearers (SiHCLW) and new contact lens wearers (NCLW). Schirmer test, tear break up time (TBUT), Ocular Surface Disease Index (OSDI) questionnaire and conjunctival impression cytology. GCD, mucin cloud height (MCH) and cell layer thickness (CLT) were measured. All measurements were performed before orthokeratology fitting and one month after fitting to assess the evolution of the changes throughout this time. No differences in tear volume and TBUT between groups were found (p>0.05). However, the OSDI score was statistically better after one month of orthokeratology lens wear than the baseline for the SiHCLW group (p=0.03). Regarding the goblet cell analysis, no differences were found in CLT and MCH from the baseline visit to the one month visit for the SiHCLW compared with NCLW groups (p>0.05). At baseline, the GCD in the SiHCLW group were statistically lower than NCLW group (p<0.001). There was a significant increase in GCD after orthokeratology fitting from 121±140cell/mm(2) to 254±130cell/mm(2) (p<0.001) in the SiHCLW group. Orthokeratology improves the dry eye subject symptoms and GCD after one month of wearing in SiHCLW. These results suggest that orthokeratology could be considered a good alternative for silicone hydrogel contact lens discomfort and dryness. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Discrimination against contact lens wearers.

PubMed

Blais, B R

1998-10-01

Employers' attitudes toward the use of contact lenses at work have become less discriminatory as lenses have improved and numerous studies have demonstrated their safety, provided that additional personal protective equipment is used when necessary. In 1994, the Occupational Safety and Health Administration published its relevant Standard (29 CFR 1910), stating that "contact lenses do not pose additional hazards to the wearer...". Accommodations required by wearers of contact lenses must comply with Title I of the Americans with Disabilities Act. However, many companies still oppose their use. The recently published policy of the American College of Occupational and Environmental Medicine and the American Academy of Ophthalmology on the use of contact lenses should lead to their wider acceptance. Elements of a corporate contact lens policy are outlined. International aspects are summarized as well.

The Effects of Silicone Hydrogel Lens Wear on the Corneal Epithelium and Risk for Microbial Keratitis

PubMed Central

Robertson, Danielle M.

2012-01-01

Previous studies using animal models and human clinical trials have demonstrated that the use of low oxygen transmissible contact lens materials produce corneal epithelial surface damage resulting in increased Pseudomonas aeruginosa (PA) adhesion and raft-mediated internalization into surface corneal epithelial cells. These findings led to the testable clinical predictions that: (1) microbial keratitis (MK) risk is expected to be greatest during the first 6 months of wear; (2) there is no difference between 6 and 30 night extended wear; and (3) that wear of hyper-oxygen transmissible lenses would reduce the reported incidence of infection. Subsequent epidemiological studies have confirmed the first two predictions; however, increased oxygen transmissibility with silicone hydrogel (SiHy) lens wear has not altered the overall incidence of MK. In this review, more recent clinical and basic studies that investigate epithelial alterations and bacterial adhesion to corneal epithelial cells following wear of SiHy lenses with and without concomitant exposure to chemically preserved multipurpose solutions (MPS) will be examined. The collective results of these studies demonstrate that even in the absence of lens-related hypoxia, MPS induce ocular surface changes during SiHy lens wear which are associated with a pathophysiological increase in PA adherence and internalization in the corneal epithelium, and therefore, predict an increased risk for PA-MK. In addition, new data supporting an interactive role for inflammation in facilitating PA adherence and internalization in the corneal epithelium will also be discussed. PMID:23266590

Corneal erosions, bacterial contamination of contact lenses, and microbial keratitis.

PubMed

Willcox, Mark D P; Naduvilath, Thomas J; Vaddavalli, Pravin K; Holden, Brien A; Ozkan, Jerome; Zhu, Hua

2010-11-01

To estimate the rate of corneal erosion coupled with gram-negative bacterial contamination of contact lenses and compare this with the rate of microbial keratitis (MK) with contact lenses. The rate of corneal erosion and contact lens contamination by gram-negative bacteria were calculated from several prospective trials. These rates were used to calculate the theoretical rate of corneal erosion happening at the same time as wearing a contact lens contaminated with gram-negative bacteria. This theoretical rate was then compared with the rates of MK reported in various epidemiological and clinical trials. Corneal erosions were more frequent during extended wear (0.6-2.6% of visits) compared with daily wear (0.01-0.05% of visits). No corneal erosions were observed for lenses worn on a daily disposable basis. Contamination rates for lenses worn on a daily disposable basis were the lowest (2.4%), whereas they were the highest for low Dk lenses worn on an extended wear basis (7.1%). The estimated rate of corneal erosions occurring at the same time as wearing lenses contaminated with gram-negative bacteria was the lowest during daily wear of low Dk lenses (1.56/10,000 [95% CI: 0.23-10.57]) and the highest during extended wear of high Dk lenses (38.55/10,000 [95% CI: 24.77-60.04]). These rates were similar in magnitude to the rates reported for MK of different hydrogel lenses worn on differing wear schedules. The coincidence of corneal erosions during lens wear with gram-negative bacterial contamination of lenses may account for the relative incidence of MK during lens wear with different lens materials and modes of use.

Conjunctival impression cytology versus routine tear function tests for dry eye evaluation in contact lens wearers.

PubMed

Kumar, Prachi; Bhargava, Rahul; Arora, Yogesh C; Kaushal, Sidharth; Kumar, Manjushri

2015-01-01

Prolonged contact lens wear is often accompanied by dryness of the eyes. The aim of this study was to compare conjunctival impression cytology (CIC) and tear film tests such as tear film break up time (TBUT) and Schirmer test for dry eye evaluation in contact lens wearers and measure their correlation with dry eye symptoms. A case control study was done at three referral eye centers. The eyes of 230 contact lens users were compared to 250 eyes of age- and sex-matched controls. Participants were recruited based on their response to a questionnaire of dry eye symptoms, (Dry Eye Scoring System, DESS(©)) and measurements of TBUT, Schirmer test, and CIC was done. A correlation analysis between symptom severity and tear film tests was performed. Pearson's coefficient, R(2) > 0.5 was considered significant. As compared to controls (r (2) = 0.010), Nelson grade correlated significantly with dry eye symptoms (r (2) = 0.765), among cases. However, there was moderate correlation between dry eye symptoms, Schirmer test, and TBUT (r (2) = 0.557 and 0.530, respectively) among cases and a weak correlation among controls (r (2) = 0.130 and 0.054, respectively). The sensitivity of TBUT was 86.4%, specificity was 82.4%, positive likelihood ratio (LR) was 4.50 [95% confidence interval (CI) 3.46-5.85)], and negative LR was 0.09. The sensitivity of the Schirmer test was 48.2%, specificity 88%, LR 2.12 (95% CI 1.48-2.96), and negative LR 0.83. CIC correlates better than Schirmer and TBUT with dry eye symptoms. It may be the most appropriate test for dry-eye evaluation in contact lens wearers.

Intraocular pressure measurement over soft contact lens by rebound tonometer: a comparative study

PubMed Central

Nacaroglu, Senay Asik; Un, Emine Seker; Ersoz, Mehmet Giray; Tasci, Yelda

2015-01-01

AIM To evaluate the intraocular pressure (IOP) measurements by Icare rebound tonometer over a contact lens in comparison with Goldmann applanation tonometry (GAT). METHODS Fifty patients using contact lens were included in this study. One of the eyes of the patients was selected randomly and their IOP were measured by rebound tonometer with and without contact lens (RTCL, RT respectively) and by GAT, as well as their central corneal thickness (CCT) by optical pachymeter. The results of both methods were compared by correlation analysis, general linear method repeated measure and Bland-Altman analysis. RESULTS Mean IOP values measured by RTCL, RT and GAT were 15.68±3.7, 14.50±3.4 and 14.16±2.8 (P<0.001), respectively. Mean IOP by RTCL was significantly higher than the measurements implemented by RT and GAT (P<0.001), while there was no difference between the measurements by GAT and RT (P=0.629). There was a good level of positive correlation between GAT and RTCL as well as RT (r=0.786 P<0.001, r=0.833 P<0.001, respectively). We have observed that CCT increase did not show any correlation with the differences of the measurements between RTCL and RT (P=0.329), RTCL and GAT (P=0.07) as well as RT and GAT (P=0.189) in linear regression model. CONCLUSION The average of the measurements over contact lens by rebound tonometer was found to be higher than what was measured by GAT. Although this difference is statistically significant, it may be clinically negligible in the normal population. PMID:26086004

Quality of image of grating target placed in vitreous of isolated pig eyes photographed through different implanted multifocal intraocular lenses.

PubMed

Inoue, Makoto; Noda, Toru; Ohnuma, Kazuhiko; Bissen-Miyajima, Hiroko; Hirakata, Akito

2011-11-01

To determine the quality of the image of a grating target placed in the vitreous of isolated pig eyes and photographed through implanted refractive and diffractive multifocal intraocular lenses (IOL). Refractive multifocal (NXG1, PY60MV), diffractive multifocal (ZM900, SA60D3) and monofocal (SA60AT, ZA9003) IOL were implanted in the capsular bag of isolated pig eyes. A grating target was placed in the vitreous and photographed through a flat or a wide-field viewing contact lens. The contrast of the grating targets of different spatial frequencies was measured. With the flat corneal contact lens, the gratings appeared clear and not distorted when viewed through the optics of the NXG1 and PY60MV for far vision but were distorted with reduced contrast when viewed through the optical zone for near vision. The images through the diffractive zone of the ZM900 and SA60D3 were more defocused than with the monofocal IOL (p < 0.005). Ghost images oriented centrifugally of the original image were seen with the ZM900 resulting in lower contrast at higher spatial frequencies than with the SA60D3 with less defocused images only in the central area. With the wide-field viewing contact lens, the images were less defocused and the contrast was comparable to both refractive and diffractive multifocal IOL. Both refractive and diffractive multifocal IOL reduced the contrast of the retinal image when viewed through a flat corneal contact lens but less defocused when viewed through a wide-field viewing contact lens. © 2011 The Authors. Acta Ophthalmologica © 2011 Acta Ophthalmologica Scandinavica Foundation.

Fluctuation in visual acuity during soft toric contact lens wear.

PubMed

Chamberlain, Paul; Morgan, Philip B; Moody, Kurt J; Maldonado-Codina, Carole

2011-04-01

To quantify changes in visual acuity (VA) with soft toric contact lenses as a result of lens movement and/or rotational instability caused by versional eye movements. A novel chart for vision assessment at near (40 cm) for soft toric contact lenses (VANT chart),consisting of a central, color-coded logMAR panel and eight peripheral letter targets set on a white background measuring 60 × 40 cm was constructed. In the developmental phase of the work, 10 subjects (20 eyes) wore 2 toric lenses in random order, and the impact of rapid and delayed eye versions in 8 directions of gaze on VANT acuity was investigated. In phase 2, 35 subjects (68 eyes) wore 4 toric lenses in random order, and a streamlined clinical protocol using the VANT chart was implemented. Standard assessments of toric lens fit and distance VA were also performed. Testing in the first phase showed no difference for change in VA for rapid vs. delayed version movements, (p = 0.17) but acuity reduction was greater for diagonal compared with horizontal/vertical versions (p = 0.06). As such, testing in phase 2 proceeded using rapid, diagonal versions only. In this second phase, there were differences for low-contrast distance VA measures between lens types (p = 0.02) and for both VANT baseline acuity (p = 0.03) and postversion acuity (p = 0.04), but no differences were found between lenses for magnitude of vision loss (p = 0.91), which was about one line. No relationship was established between the magnitude of vision loss and measured rotational stability (p = 0.75). This work has demonstrated that conventional approaches to measuring VA do not fully replicate the "real world" experience of soft toric lens wearers. The VANT chart has shown that VA is reduced immediately after versional eye movements and suggests that more dynamic methods of assessing visual performance should be considered for soft toric contact lens wearers, especially given the apparent inability of lens stability measurements to predict visual performance.

[Some special indications for wearing contact lenses (author's transl)].

PubMed

Müller, K

1978-12-01

The typical distinguishing features of special cases which require contact lenses for satisfactory vision are described. Hence in the first case with anisometria associated with irregular astigmatism of one eye, to which a toric soft contact lens was adapted. In the second case a visual acuity of only 0,6 monocular was attained with the best spectacle lens, however with contact lense the visual acuity was 1.25. Here a verdict from a social court is mentioned, which obliged the sickness insurance to take over the costs for such a case. In the third case the adaptation of contact lenses was undertaken after radical bilateral keratoplasty because of parenchymatous keratitis, and an improvement in visual acuity of at least 400% resulted.

Characterization of Soft Contact Lens Fitting Using Ultra-Long Scan Depth Optical Coherence Tomography

PubMed Central

Li, Ming; Lu, Fan

2017-01-01

Objectives To evaluate the centration and movement of soft contact lenses and to verify the repeatability of two repeated measurements of the lens centration and movement using ultra-long scan depth optical coherence tomography (UL-OCT). Methods A 1-day Acuvue® Define™ lens was tested on both eyes of 10 subjects (5 males and 5 females; mean age, 31.6 years). The centration and blink-induced movement of the contact lens were measured using UL-OCT at 5 min and 30 min after insertion. The measurements were repeated once at each checkpoint. Results Good repeatability was found in the lens centration and movement between the two repeated measurements at either checkpoint. The values of the lens movement were 0.457 ± 0.248 mm and 0.402 ± 0.229 mm at 5 min and decreased to 0.197 ± 0.065 mm and 0.211 ± 0.110 mm at 30 min after insertion for the right and left eyes, respectively (P < 0.05). Conclusions The custom-built UL-OCT presented good repeatability of centration and movement in Define lenses at 5 min and 30 min after insertion. Most of the lenses were centered temporal and inferior to the cornea during the first 30 min wearing period. Compared with 5 min after insertion, the lens was centered better and exhibited less movement at 30 min. PMID:28751981

The effect of fractal contact lenses on peripheral refraction in myopic model eyes.

PubMed

Rodriguez-Vallejo, Manuel; Benlloch, Josefa; Pons, Amparo; Monsoriu, Juan A; Furlan, Walter D

2014-12-01

To test multizone contact lenses in model eyes: Fractal Contact Lenses (FCLs), designed to induce myopic peripheral refractive error (PRE). Zemax ray-tracing software was employed to simulate myopic and accommodation-dependent model eyes fitted with FCLs. PRE, defined in terms of mean sphere M and 90°-180° astigmatism J180, was computed at different peripheral positions, ranging from 0 to 35° in steps of 5°, and for different pupil diameters (PDs). Simulated visual performance and changes in the PRE were also analyzed for contact lens decentration and model eye accommodation. For comparison purposes, the same simulations were performed with another commercially available contact lens designed for the same intended use: the Dual Focus (DF). PRE was greater with FCL than with DF when both designs were tested for a 3.5 mm PD, and with and without decentration of the lenses. However, PRE depended on PD with both multizone lenses, with a remarkable reduction of the myopic relative effect for a PD of 5.5 mm. The myopic PRE with contact lenses decreased as the myopic refractive error increased, but this could be compensated by increasing the power of treatment zones. A peripheral myopic shift was also induced by the FCLs in the accommodated model eye. In regard to visual performance, a myopia under-correction with reference to the circle of least confusion was obtained in all cases for a 5.5 mm PD. The ghost images, generated by treatment zones of FCL, were dimmer than the ones produced with DF lens of the same power. FCLs produce a peripheral myopic defocus without compromising central vision in photopic conditions. FCLs have several design parameters that can be varied to obtain optimum results: lens diameter, number of zones, addition and asphericity; resulting in a very promising customized lens for the treatment of myopia progression.

[Early clinical diagnosis of acanthamoeba keratitis. A study of 70 eyes].

PubMed

Bernauer, W; Duguid, G I; Dart, J K

1996-05-01

Acanthamoeba keratitis is an uncommon condition which is usually associated with contact lens wear. The use of home made saline and poor hygiene are important risk factors. Early diagnosis is crucial since these cases respond well to medical therapy. The purpose of this paper is to describe and demonstrate early clinical signs. Between September 1992 and October 1994, 70 cases of acanthamoeba keratitis, one of them bilateral, were prospectively monitored at Moorfields Eye Hospital in London. A database of all patients was set up and the clinical findings, diagnostic methods, therapeutic interventions and the outcome were recorded. 66 patients (96%) were contact lens wearers, 64 of them (97%) wore soft lenses. The mean interval between first symptoms and correct diagnosis was 42%. The most frequent initial diagnoses were "unclear keratoconjunctivitis" and "herpetic keratitis". Early corneal findings included punctate keratopathy (n = 14; 20%), pseudodendrites (n = 4; 6%), epithelial infiltrates (n = 17; 24%), diffuse or focal sub-epithelial infiltrates (n = 36; 51%) and radial keratoneuritis (n = 5; 7%). Ring infiltrates (n = 13; 18%) and corneal ulceration (n = 13) were late signs. When the above corneal findings are observed, particularly in contact lens wearers, the diagnosis of acanthamoeba keratitis should be considered. The diagnosis of "herpetic keratitis" in association with contact lens wear should be encountered with scepticism.

Power profiles and short-term visual performance of soft contact lenses.

PubMed

Papas, Eric; Dahms, Anne; Carnt, Nicole; Tahhan, Nina; Ehrmann, Klaus

2009-04-01

To investigate the manner in which contemporary soft contact lenses differ in the distribution of optical power within their optic zones and establish if these variations affect the vision of wearers or the prescribing procedure for back vertex power (BVP). By using a Visionix VC 2001 contact lens power analyzer, power profiles were measured across the optic zones of the following contemporary contact lenses ACUVUE 2, ACUVUE ADVANCE, O2OPTIX, NIGHT & DAY and PureVision. Single BVP measures were obtained using a Nikon projection lensometer. Visual performance was assessed in 28 masked subjects who wore each lens type in random order. Measurements taken were high and low contrast visual acuity in normal illumination (250 Cd/m), high contrast acuity in reduced illumination (5 Cd/m), subjective visual quality using a numerical rating scale, and visual satisfaction rating using a Likert scale. Marked differences in the distribution of optical power across the optic zone were evident among the lens types. No significant differences were found for any of the visual performance variables (p > 0.05, analysis of variance with repeated measures and Friedman test). Variations in power profile between contemporary soft lens types exist but do not, in general, result in measurable visual performance differences in the short term, nor do they substantially influence the BVP required for optimal correction.

Fusarium Keratitis in Germany

PubMed Central

Stasch, Serena; Kaerger, Kerstin; Hamprecht, Axel; Roth, Mathias; Cornely, Oliver A.; Geerling, Gerd; Mackenzie, Colin R.; Kurzai, Oliver; von Lilienfeld-Toal, Marie

2017-01-01

ABSTRACT Fusarium keratitis is a destructive eye infection that is difficult to treat and results in poor outcome. In tropical and subtropical areas, the infection is relatively common and associated with trauma or chronic eye diseases. However, in recent years, an increased incidence has been reported in temperate climate regions. At the German National Reference Center, we have observed a steady increase in case numbers since 2014. Here, we present the first German case series of eye infections with Fusarium species. We identified Fusarium isolates from the eye or eye-related material from 22 patients in 2014 and 2015. Thirteen isolates belonged to the Fusarium solani species complex (FSSC), 6 isolates belonged to the Fusarium oxysporum species complex (FOSC), and three isolates belonged to the Fusarium fujikuroi species complex (FFSC). FSSC was isolated in 13 of 15 (85%) definite infections and FOSC in 3 of 4 (75%) definite contaminations. Furthermore, diagnosis from contact lens swabs or a culture of contact lens solution turned out to be highly unreliable. FSSC isolates differed from FOSC and FFSC by a distinctly higher MIC for terbinafine. Outcome was often adverse, with 10 patients requiring keratoplasty or enucleation. The use of natamycin as the most effective agent against keratitis caused by filamentous fungi was rare in Germany, possibly due to restricted availability. Keratitis caused by Fusarium spp. (usually FSSC) appears to be a relevant clinical problem in Germany, with the use of contact lenses as the predominant risk factor. Its outcome is often adverse. PMID:28747368

Clinical Performance of a New Bitangential Mini-scleral Lens.

PubMed

Otten, Henny M; van der Linden, Bart J J J; Visser, Esther-Simone

2018-06-01

New bitangential mini-scleral lens designs provide a highly precise fit, follow the scleral shape, are comfortable to wear, and can correct residual astigmatism. This new scleral lens design complements the arsenal of medical contact lenses available to eye care practitioners. The aim of this study was to evaluate the subjective and objective performance of a new mini-scleral lens design with a bitangential periphery. In this observational study, data were collected for up to 15 months (median, 84 days; interquartile range, 76 days) from the left eyes of 133 patients fitted with this newly designed lens. Data were recorded during regular visits at Visser Contact Lens Practice's scleral lens clinics: diagnosis, clinical indication for scleral lenses, previous contact lens type, subjective performance, horizontal visible iris diameter, corrected distance visual acuity, and scleral lens fitting characteristics. The most common indication was keratoconus (45%), followed by irregular astigmatism (22%), keratoplasty (16.5%), ocular surface disease (13.5%), and other forms of irregular astigmatism (3%). The majority of patients (79%) scored comfort as either a 4 or 5 (out of 5), and 82% wore their lenses 12 hours or longer a day. Most lenses (81%) had a diameter of 16 mm (median, 16 mm; range, 15.5 to 17 mm) and were composed of Boston XO2 (46%), Menicon Z (44%), Boston XO (9%), or Boston Equalens II (1%). The median corrected distance visual acuity was 0.022 logarithm of the minimal angle of resolution (interquartile range, 0.155). The fitting characteristics revealed optimal values for centration and movement in 91% and 83%, respectively. Finally, the median stabilization axis was 50 degrees. New mini-scleral lenses with bitangential peripheral geometry yield satisfactory clinical results and good subjective performance and are therefore an effective option for managing patients who have irregular astigmatism or other corneal pathology.

A Laboratory Assessment of Factors That Affect Bacterial Adhesion to Contact Lenses

PubMed Central

Dutta, Debarun; Willcox, Mark DP

2013-01-01

Adhesion of pathogenic microbes, particularly bacteria, to contact lenses is implicated in contact lens related microbial adverse events. Various in vitro conditions such as type of bacteria, the size of initial inoculum, contact lens material, nutritional content of media, and incubation period can influence bacterial adhesion to contact lenses and the current study investigated the effect of these conditions on bacterial adhesion to contact lenses. There was no significant difference in numbers of bacteria that adhered to hydrogel etafilcon A or silicone hydrogel senofilcon A contact lenses. Pseudomonas aeruginosa adhered in higher numbers compared to Staphylococcus aureus. Within a genera/species, adhesion of different bacterial strains did not differ appreciably. The size of initial inoculum, nutritional content of media, and incubation period played significant roles in bacterial adhesion to lenses. A set of in vitro assay conditions to help standardize adhesion between studies have been recommended. PMID:24833224

Flexure-Ring for Centering a Concave Lens in a Bore of a Housing for an Optical System

NASA Technical Reports Server (NTRS)

Ford, Virginia G. (Inventor)

2002-01-01

A flexure-ring is provided for centering a lens in a bore of a housing with 3N lens contacting stubs, where N is an integer equal to or greater than one. The stubs are formed by increasing the inside diameter of the ring made to fit tightly around a lens except at 3N locations for the aforesaid stubs, and said ring having an outside diameter made to fit tightly inside the housing bore locations. Behind each stub, a segment of the ring is removed down to a chord perpendicular to a ring diameter passing through the center of each stub. That chord is selected to have a length greater than the lens contacting surface of the stub, thereby to produce a reduced cross section of the ring on both sides of the stub to serve as flexures in relieving stresses due to different coefficients of thermal expansion of the three parts involved due to changes in temperature while in use.

Sustained Ocular Delivery of Ciprofloxacin Using Nanospheres and Conventional Contact Lens Materials

PubMed Central

Garhwal, Rahul; Shady, Sally F.; Ellis, Edward J.; Ellis, Jeanne Y.; Leahy, Charles D.; McCarthy, Stephen P.; Crawford, Kathryn S.

2012-01-01

Purpose. To formulate conventional contact lenses that incorporate nanosphere-encapsulated antibiotic and demonstrate that the lenses provide for sustained antibacterial activity. Methods. A copolymer composed of pullulan and polycaprolactone (PCL) was used to synthesize core-shell nanospheres that encapsulated ciprofloxacin. Bactericidal activity of the nanosphere-encapsulated ciprofloxacin (nanosphere/cipro) was tested by using liquid cultures of either Staphylococcus aureus or Pseudomonas aeruginosa. Nanosphere/cipro was then incorporated into HEMA-based contact lenses that were tested for growth inhibition of S. aureus or P. aeruginosa in liquid cultures inoculated daily with fresh bacteria. Lens designs included thin or thick lenses incorporating nanosphere/cipro and ciprofloxacin-HCl-soaked Acuvue lenses (Acuvue; Johnson & Johnson Vision Care, Inc., Jacksonville, FL). Results. Less than 2 μg/mL of nanosphere/cipro effectively inhibited the proliferation of cultures inoculated with 107 or 108 bacteria/mL of S. aureus and P. aeruginosa, respectively. HEMA-based contact lenses polymerized with nanosphere/cipro were transparent, effectively inhibited the proliferation of greater than 107/mL of bacteria added daily over 3 days of culture, and killed up to 5 × 109 total microbes in a single inoculation. A thicker lens design provided additional inhibition of bacterial growth for up to 96 hours. Conclusions. Core-shell nanospheres loaded with an antibiotic can be incorporated into a conventional, transparent contact lens and provide for sustained and effective bactericidal activity and thereby provide a new drug delivery platform for widespread use in treating ocular disorders. PMID:22266514

Silicone hydrogel mini-scleral contact lenses in early stage after corneal collagen cross-linking for keratoconus: a retrospective case series.

PubMed

Severinsky, Boris; Wajnsztajn, Denise; Frucht-Pery, Joseph

2013-11-01

 The aim was to the evaluate performance of a novel silicone hydrogel mini-scleral contact lens (SHmS) for optical correction of keratoconus in the early stages after the corneal collagen cross-linking procedure (CXL).  We retrospectively analysed the visual acuity improvement and corneal adaptation in the first 10 eyes of nine patients fitted with SHmS lenses one to 3.5 months after corneal collagen cross-linking. The lenses were designed to rest over the patients' sclera and peri-limbal cornea and vault the central cornea with minimal support over it. Visual acuities with manifest refraction and contact lenses, refractive and topographical values (Kmin and Kmax) were evaluated on lens dispensing and after six month of lens wearing. Ocular physiological responses were evaluated using the Institute of Eye Research (IER) grading scales.  SHmS fitting was performed 2.1 ± 0.97 (SD) months after collagen cross-linking. Mean follow up was 10.9 ± 4.41 months (range six to 18 months). Mean decimal visual acuity with SHmS was 0.66 ± 0.22 (approximately 6/9 Snellen fraction, range 0.3 to 0.1) or 0.75 ± 0.14 (approximately 6/8.1, range 0.5 to 1.0), when omitting two amblyopic eyes. Nine (90 per cent) eyes were successfully fitted, that is, able to wear the lenses for 10 hours per day or longer. Mean wearing time was 11.7 hours (range six to 14) per day. No corneal neovascularisation or papillary reaction was found in all fitted eyes.  SHmS contact lenses provide successful visual rehabilitation shortly after corneal collagen cross-linking. This new soft contact lens design with scleral fixation and minimal apical touch was demonstrated to be safe shortly after collagen cross-linking, as the avoidance of contact with the treated zone minimises contact lens influence on corneal recovery. © 2013 The Authors. Clinical and Experimental Optometry © 2013 Optometrists Association Australia.

Polymerizable-group capped ZnS nanoparticle for high refractive index inorganic-organic hydrogel contact lens.

PubMed

Zhao, Peili; Xu, Jinku; Zhang, Yongchun; Zhu, Weiyue; Cui, Yuezhi

2018-09-01

Refractive index (RI) is an important parameter for contact lens biomaterials. In this paper, a novel polymerizable-group capped ZnS nanoparticle (NP) was synthesized by chemical link between hydroxyl group on the surface of ZnS (ME-capped) and isocyanate group of polymerizable molecule of 2-isocyanatoethyl methacrylate. Then the ZnS NP copolymerized with monomer of 2-hydroxyethyl methacrylate (HEMA) and N,N-dimethylacrylamide (DMA) to prepare high refractive index hydrogel contact lens with high content of inorganic ZnS NP. Increasing polymerizable-group capped ZnS content in the hydrogels improved its RI value and mechanical properties, however decreased slightly its transmittance, equilibrium (ESR) and lysozyme deposition on the hydrogel surface. The ZnS-containing hydrogels possessed good cytocompatibility and in vivo biocompatibility in rabbit eyes, demonstrating a potential application as high RI ocular refractive correction biomaterial. Copyright © 2018 Elsevier B.V. All rights reserved.

Broad spectrum antimicrobial activity of melimine covalently bound to contact lenses.

PubMed

Dutta, Debarun; Cole, Nerida; Kumar, Naresh; Willcox, Mark D P

2013-01-07

To develop a stable antimicrobial contact lens, which is effective against the International Organization for Standardization (ISO) panel microorganisms, Acanthamoeba castellanii and drug resistant strains of Pseudomonas aeruginosa and Staphylococcus aureus. Melimine was covalently incorporated into etafilcon A lenses. The amount of peptide present on the lens surface was quantified using amino acid analysis. After coating, the heat stability (121°C), lens surface hydrophobicity (by captive bubble), and in vitro cytotoxicity to mouse L929 cells of the lenses were investigated. Antimicrobial activity against the micro-organisms was evaluated by viable plate count and fluorescence microscopy, measuring the proportion of cell death compared with control lenses with no melimine. The most effective concentration was determined to be 152 ± 44 μg lens(-1) melimine on the lens surface. After coating, lenses were relatively hydrophilic and were nontoxic to mammalian cells. The activity remained high after autoclaving (e.g., 3.1, 3.9, 1.2, and 1.0 log inhibition against P. aeruginosa, S. aureus, A. castellanii, and Fusarium solani, respectively). Fluorescence microscopy confirmed significantly reduced (P < 0.001) adhesion of viable bacteria to melimine contact lenses. Viable count confirmed that lenses were active against all the bacteria and fungi from the ISO panel, Acanthamoeba and gave at least 2 log inhibition against all the multidrug resistant S. aureus and P. aeruginosa strains. Melimine may offer excellent potential for development as a broad spectrum antimicrobial coating for contact lenses, showing activity against all the bacterial and fungal ISO panel microorganisms, Acanthamoeba, and antibiotic resistant strains of P. aeruginosa and S. aureus.

Hand hygiene prior to contact lens handling is problematical.

PubMed

McMonnies, Charles W

2012-04-01

To establish guidelines for contact lens wearers' hand hygiene practices which achieve a balance between minimising risk of infection and reasonable expectations on the ability of patients to follow them. Evidence has been obtained from publications via PubMed, Advanced Medline Search, Cochrane Reviews, Google Scholar and using the key words hand hygiene, washing and contact lens. Guidelines for effective hand washing and the bother involved vary according to the level of hygiene required. High levels of non-compliance with hand hygiene practices, even among healthcare workers, gives an indication of how important the level of bother involved when following guidelines can be in contributing to non-compliance. Better patient education to improve hand washing techniques as well as patient attitudes toward hand hygiene are needed to reduce high non-compliance levels. Better hand hygiene techniques and higher frequency of their application give the prospect of reduced risk of infection and of any discomfort that arises from increased lens and ocular bioburden. In order that adoption rates might be maximised, the guidelines which have been distilled from this review attempt to strike a balance between technique redundancy and the associated higher levels of hygiene achieved and the possibility that the perception of too much bother involved could reduce participation rates. The guidelines have been expanded by the inclusion of suggested explanatory information in the expectation that helping patients to understand why the recommendations are made will have the effect of increasing their adoption. Copyright © 2011 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Ultra-high resolution of radiocesium distribution detection based on Cherenkov light imaging

NASA Astrophysics Data System (ADS)

Yamamoto, Seiichi; Ogata, Yoshimune; Kawachi, Naoki; Suzui, Nobuo; Yin, Yong-Gen; Fujimaki, Shu

2015-03-01

After the nuclear disaster in Fukushima, radiocesium contamination became a serious scientific concern and research of its effects on plants increased. In such plant studies, high resolution images of radiocesium are required without contacting the subjects. Cherenkov light imaging of beta radionuclides has inherently high resolution and is promising for plant research. Since 137Cs and 134Cs emit beta particles, Cherenkov light imaging will be useful for the imaging of radiocesium distribution. Consequently, we developed and tested a Cherenkov light imaging system. We used a high sensitivity cooled charge coupled device (CCD) camera (Hamamatsu Photonics, ORCA2-ER) for imaging Cherenkov light from 137Cs. A bright lens (Xenon, F-number: 0.95, lens diameter: 25 mm) was mounted on the camera and placed in a black box. With a 100-μm 137Cs point source, we obtained 220-μm spatial resolution in the Cherenkov light image. With a 1-mm diameter, 320-kBq 137Cs point source, the source was distinguished within 2-s. We successfully obtained Cherenkov light images of a plant whose root was dipped in a 137Cs solution, radiocesium-containing samples as well as line and character phantom images with our imaging system. Cherenkov light imaging is promising for the high resolution imaging of radiocesium distribution without contacting the subject.

Laser welding of biological tissue: experimental studies in ophthalmology

NASA Astrophysics Data System (ADS)

Pini, Roberto; Rossi, Francesca; Menabuoni, Luca

2006-04-01

In this paper we present an original approach to laser welding of ocular media. Attention is focused on laser welding of the cornea and lens capsule. The process is based on the interaction of near infrared diode laser radiation (at 810 nm) with tissue that was previously stained with an Indocyanine Green solution in sterile water. The topical application of the chromophore makes possible a selective heating of the tissue, which results in a homogenous welding effect with low thermal damage to the surrounding tissue. Experimental tests were performed ex vivo on both capsule and cornea, and in vivo (rabbits) only on the cornea, in order to characterize the process as a whole. Spectrophotometric, biomechanical, and thermal measurements were carried out in order to study the laser-tissue interaction, while morphological, histological and auto-florescence microscopy analyses made during a follow-up study provided information on the healing process in welded rabbit corneas. The welding procedure was set up according to the type of tissue, with the staining procedure and irradiation conditions being optimized in each case. Our test indicated that: 1) laser welding of corneal wounds, which is a non contact technique performed at low continuous wave laser power (12 W/cm2), can be proposed as a support to or substitute for the standard suturing technique in cataract surgery and in penetrating keratoplasty (in corneal transplants); 2) laser welding of the lens capsule requires a "contact irradiating technique" in order to be efficiently performed, since the tissue is in underwater conditions, with single spot pulses of about 100 J/cm2 fluence and pulse duration around 100 ms. In the latter case, laser welding was proposed as a tool for assisting closure of the lens capsule after the lens refilling procedure (Phaco-ersatz), or for repairing capsular breaks induced by accidental traumas or produced intraoperatively.

In situ measurements of thin films in bovine serum lubricated contacts using optical interferometry.

PubMed

Vrbka, Martin; Křupka, Ivan; Hartl, Martin; Návrat, Tomáš; Gallo, Jiří; Galandáková, Adéla

2014-02-01

The aim of this study is to consider the relevance of in situ measurements of bovine serum film thickness in the optical test device that could be related to the function of the artificial hip joint. It is mainly focussed on the effect of the hydrophobicity or hydrophilicity of the transparent surface and the effect of its geometry. Film thickness measurements were performed using ball-on-disc and lens-on-disc configurations of optical test device as a function of time. Chromatic interferograms were recorded with a high-speed complementary metal-oxide semiconductor digital camera and evaluated with thin film colorimetric interferometry. It was clarified that a chromium layer covering the glass disc has a hydrophobic behaviour which supports the adsorption of proteins contained in the bovine serum solution, thereby a thicker lubricating film is formed. On the contrary, the protein film formation was not observed when the disc was covered with a silica layer having a hydrophilic behaviour. In this case, a very thin lubricating film was formed only due to the hydrodynamic effect. Metal and ceramic balls have no substantial effect on lubricant film formation although their contact surfaces have relatively different wettability. It was confirmed that conformity of contacting surfaces and kinematic conditions has fundamental effect on bovine serum film formation. In the ball-on-disc configuration, the lubricant film is formed predominantly due to protein aggregations, which pass through the contact zone and increase the film thickness. In the more conformal ball-on-lens configuration, the lubricant film is formed predominantly due to hydrodynamic effect, thereby the film thickness is kept constant during measurement.

Increased numbers of Demodex in contact lens wearers.

PubMed

Jalbert, Isabelle; Rejab, Shazana

2015-06-01

The aim of this study was to determine if Demodex infestation is more frequent in contact lens wearers than in nonwearers. Secondary aims were to evaluate the effects of Demodex on the ocular surface (symptoms and signs) and to evaluate the ability of confocal laser scanning microscopy to detect and quantify the Demodex infestation compared with the conventional light microscopic technique. Forty Asian female participants (20 nonwearers, 20 lens wearers) with a mean (± SD) age of 27 (± 9) years were recruited. Ocular comfort scores (Ocular Surface Disease Index, Ocular Comfort Index, and Dry Eye Questionnaire), vital staining (corneal, conjunctival, and lid wiper), tear osmolarity, tear breakup time, and meibomian gland evaluation were evaluated. Demodex was detected using in vivo confocal microscopy and conventional light microscopy. The number of Demodex was higher in lens wearers than in nonwearers (7.6 [± 5.8] vs. 5.0 [± 3.1]; p = 0.02). Demodex was observed in a large majority (90%) of lens wearers and in 65% of nonwearers using confocal microscopy (p = 0.06). The detection rate was lower in both groups using conventional light microscopy (p = 0.003) where Demodex could only be confirmed in 70% and 60% of lens wearers and nonwearers, respectively. The number of Demodex tended to increase with age (ρ = 0.28, p = 0.08), but Demodex did not appear to affect ocular comfort or any clinical signs (p > 0.05). Contact lens wearers harbor Demodex as frequently as nonwearers and in higher numbers, which is best detected using in vivo confocal microscopy. The significance of these findings is uncertain because no associations were found with any symptoms and signs of dry eye disease.

Charged black lens in de Sitter space

NASA Astrophysics Data System (ADS)

Tomizawa, Shinya

2018-02-01

We obtain a charged black lens solution in the five-dimensional Einstein-Maxwell-Chern-Simons theory with a positive cosmological constant. It is shown that the solution obtained here describes the formation of a black hole with the spatial cross section of a sphere from that of the lens space of L (n ,1 ) in five-dimensional de Sitter space.

The Management of Refractory Dry Eye With Semi-Scleral Contact Lens.

PubMed

Yuksel, Erdem; Bilgihan, Kamil; Novruzlu, Şahin; Yuksel, Nilay; Koksal, Murat

2018-05-01

We presented a case of refractory dry eye management with semi-scleral contact lens. Dry eye was associated with facial nerve (cranial nerve VII) palsy as a result of cerebellopontine angle tumor surgery. She was treated with several topical treatments and punctal plug. Despite the treatments, her symptoms still persisted. Her ophthalmic examination revealed scleral exposure because of lagophthalmos, conjunctival hyperemia, corneal debris, scar, and diffuse punctate epitheliopathy on her right eye. Lissamine green staining showed diffuse conjunctival and corneal staining. Therapeutic semi-scleral lenses were fitted. The corneal findings were resolved and the quality of patient life was improved with the aid of semi-scleral lens after 3 months.

Scleral contact lenses for the management of complicated ptosis.

PubMed

Katsoulos, Konstantinos; Rallatos, Gerasimos Livir; Mavrikakis, Ioannis

2018-06-01

To present the management of three patients suffering from ptosis of various etiologies, with scleral contact lenses. Three patients (five eyes) with ptosis resulting from levator dehiscence due to long-term rigid gas permeable contact lens wear for keratoconus, phthisis bulbi, and myopathy due to Kearns-Sayre syndrome were identified during a 2-year period. They were fitted with scleral contact lenses in order to provide cosmesis by lifting the upper eyelid with the bulk of the lens, and simultaneously provide vision correction where applicable. The scleral contact lenses provided comfortable wear, significantly improved cosmesis as both palpebral aperture and marginal reflex distance were increased, and visual acuity was also subjectively and objectively improved. Two of the patients opted for the scleral contact lenses, whereas the parents of the third patient, a 10-year-old girl with Kearns-Sayre syndrome, chose to undergo ptosis surgery due to handling issues of the scleral contact lenses. Scleral contact lenses can be a useful addition to the treatment option for patients with complicated ptosis.

Beauveria keratitis and biopesticides: case histories and a random amplification of polymorphic DNA comparison.

PubMed

Pariseau, Brett; Nehls, Sarah; Ogawa, Gregory S H; Sutton, Deanna A; Wickes, Brian L; Romanelli, Anna M

2010-02-01

The purposes of this study were to describe 2 contact lens-associated Beauveria keratitis cases and to compare the isolates of 3 contact lens-associated Beauveria keratitis cases with Beauveria-based biopesticides using random amplification of polymorphic DNA (RAPD). A 55-year-old diabetic woman from New Mexico and a 31-year-old healthy woman from southern Wisconsin developed soft contact lens-related corneal ulcers unresponsive to topical moxifloxacin and prednisolone acetate drops. Their corneal cultures grew B. bassiana. These isolates, an isolate from a third soft contact lens-related Beauveria keratitis case, and Beauveria-based biopesticides sold in the United States were analyzed using morphological features, DNA sequencing, and RAPD. A PubMed, Cochrane Library, OVID, UpToDate, and Google search using the term "Beauveria" found only 9 reported Beauveria keratitis infections. Patient 1 responded to topical natamycin, ketoconazole, and 200 mg oral ketoconazole twice daily before developing a secondary bacterial infection requiring penetrating keratoplasty. After subsequent cataract surgery, the best-corrected visual acuity was 20/20. Patient 2 was treated with topical natamycin, topical amphotericin, and 200 mg oral voriconazole twice daily for 1 month with residual scarring and a best-corrected visual acuity of 20/25. RAPD showed that all isolates were unrelated. Although earlier reported Beauveria keratitis cases occurred after corneal injury in patients who did not wear contact lenses, 3 recent patients wore soft contact lenses and denied trauma, mirroring a changing trend in microbial keratitis. RAPD analysis showed that the Beauveria isolates were unrelated to one another and to Beauveria-based biopesticides. In Patient 2, oral voriconazole worked well.

The effect of octylglucoside and sodium cholate in Staphylococcus epidermidis and Pseudomonas aeruginosa adhesion to soft contact lenses.

PubMed

Santos, Lívia; Rodrigues, Diana; Lira, Madalena; Oliveira, Rosario; Real Oliveira, M Elisabete C D; Vilar, Eva Yebra-Pimentel; Azeredo, Joana

2007-05-01

In this study, the effect of the natural surfactants octylglucoside and sodium cholate in inhibiting Staphylococcus epidermidis and Pseudomonas aeruginosa adhesion to conventional and silicone-hydrogel contact lenses (CL) was assessed. Hydrophobicity was also evaluated to conditioned and nonconditioned CL. The inhibiting effect of the tested surfactants was determined through "in vitro" adhesion studies to conditioned and nonconditioned CL followed by image acquisition and cell enumeration. Hydrophobicity was evaluated through contact angle measurements using the advancing type technique on air. Sodium cholate exhibits a very low capability to inhibit microbial adhesion. Conversely, octylglucoside effectively inhibited microbial adhesion in both types of lenses. This surfactant exhibited an even greater performance than a multipurpose lens care solution used as control. Octylglucoside was the only tested surfactant able to lower the hydrophobicity of all CL, which can explain its high performance. The results obtained in this study point out the potential of octylglucoside as a conditioning agent to prevent microbial colonization.

Corneal Protection for Burn Patients

DTIC Science & Technology

2013-10-01

inflammation. BODY This Grant Agreement was for a joint project with Col Anthony J. Johnson, MD, PI on Grant Agreement W81XWH-09-2-0069. The ...project could be placed on the inflamed eye in a Prokera®–like device or be sutured to the cornea as is done in AM transplantation. However we have...in place and prevent bacterial infection under the contact lens. A hydrophilic hydrogel contact lens was sealed between two discs of AM. One of

Effect of povidone 2% preservative-free eyedrops on contact lens wearers with computer visual syndrome: pilot study.

PubMed

Guillon, Michel; Maissa, Cecile; Pouliquen, Pascale; Delval, Laurent

2004-01-01

To show that the use of povidone 2% preservative-free lubricating eyedrops reduces computer visual syndrome in contact lens wearers and to identify the best eyedrop instillation protocols. The test product was FILMABAK a CE-marked nonpreserved lubricant, povidone 2% delivered by the ABAK system. Three dispensing modalities were evaluated during contact lens wear and computer use: hourly instillation, symptom-related instillation, and patient's own instillation. During sustained computer use, a decrease in symptoms associated with the use of povidone 2% was statistically and clinically significant. However, the symptoms were not fully eliminated by the use of the test eyedrop. The three instillation routines achieved similar beneficial effects. No significant changes in ocular tissue response were observed, and the staining recorded after sustained computer use remained low. The use of povidone 2% preservative-free lubricating eyedrops under any of the three instillation modalities tested was also associated with a slight improvement in dynamic visual acuity. The use of povidone 2% preservative-free eyedrops was associated with an improvement in symptoms during sustained computer use. Any of the three instillation modalities decreased symptoms of ocular tiredness, dryness, and difficulty of focus; maintained an unchanged corneal surface; and improved dynamic visual acuity. Therefore, the most patient-friendly modality (patient's own instillation modality from symptom onset) could be recommended to contact lens wearers with computer visual syndrome.

Removal of intraocular foreign body in anterior chamber angle with prism contact lens and 23-gauge foreign body forceps.

PubMed

Huang, Yan-Ming; Yan, Hua; Cai, Jin-Hong; Li, Hai-Bo

2017-01-01

To introduce a novel approach in removal of anterior chamber angle foreign body (ACFB) using a prism contact lens and 23-gauge foreign body forceps. Data of 42 eyes of 42 patients who had undergone removal of ACFB using a prism contact lens and 23-gauge foreign body forceps from January 2008 to October 2013 were collected and analyzed. Twenty eyes in group A received the conventional approach by using toothed forceps through corneal limbus incision, and 22 eyes in group B underwent the novel method through the opposite corneal limbus incision. The success rate of ACFB once removal was 75% (15/20) in group A, and 100% (22/22) in group B. The average operation time of group A was significantly longer compared with group B (34.9±9.88min vs 22.13±8.85min; P <0.05). The average size of corneal limbus incision in group A was significantly larger than that of group B (4.85±1.89 mm vs 3.95±1.17 mm; P <0.05). The corneal limbus incision suturing were conducted in all eyes in group A, and only 5 eyes in group B. Removal of ACFB using a prism contact lens and 23-gauge foreign body forceps is a safer, more effective, and convenient technique compared with the conventional approach.

Modeling Corneal Oxygen with Scleral Gas Permeable Lens Wear.

PubMed

Compañ, Vicente; Aguilella-Arzo, Marcel; Edrington, Timothy B; Weissman, Barry A

2016-11-01

The main goal of this current work is to use an updated calculation paradigm, and updated boundary conditions, to provide theoretical guidelines to assist the clinician whose goal is to improve his or her scleral gas permeable (GP) contact lens wearing patients' anterior corneal oxygen supply. Our model uses a variable value of corneal oxygen consumption developed through Monod equations that disallows negative oxygen tensions within the stroma to predict oxygen tension at the anterior corneal surface of scleral GP contact lens wearing eyes, and to describe oxygen tension and flux profiles, for various boundary conditions, through the lens, tears, and cornea. We use several updated tissue and boundary parameters in our model. Tear exchange with GP scleral lenses is considered nonexistent in this model. The majority of current scleral GP contact lenses should produce some levels of corneal hypoxia under open eye conditions. Only lenses producing the thinnest of tear vaults should result in anterior corneal surface oxygen tensions greater than a presumed critical oxygen tension of 100 mmHg. We also find that corneal oxygen tension and flux are each more sensitive to modification in tear vault than to changes in lens oxygen permeability, within the ranges of current clinical manipulation. Our study suggests that clinicians would be prudent to prescribe scleral GP lenses manufactured from higher oxygen permeability materials and especially to fit without excessive corneal clearance.

16 CFR 456.5 - Rules applicable to prescriptions for contact lenses and related issues.

Code of Federal Regulations, 2010 CFR

2010-01-01

... contact lenses and related issues. 456.5 Section 456.5 Commercial Practices FEDERAL TRADE COMMISSION TRADE... contact lenses and related issues. Rules applicable to prescriptions for contact lenses and related issues may be found at 16 CFR part 315 (Contact Lens Rule). [69 FR 40511, July 2, 2004] ...

Optics of wide-angle panoramic viewing system-assisted vitreous surgery.

PubMed

Chalam, Kakarla V; Shah, Vinay A

2004-01-01

The purpose of the article is to describe the optics of the contact wide-angle lens system with stereo-reinverter for vitreous surgery. A panoramic viewing system is made up of two components; an indirect ophthalmoscopy lens system for fundus image viewing, which is placed on the patient's cornea as a contact lens, and a separate removable prism system for reinversion of the image mounted on the microscope above the zooming system. The system provides a 104 degrees field of view in a phakic emmetropic eye with minification, which can be magnified by the operating microscope. It permits a binocular stereoptic view even through a small pupil (3 mm) or larger. In an air-filled phakic eye, field of view increases to approximately 130 degrees. The obtained image of the patient's fundus is reinverted to form true, erect, stereoscopic image by the reinversion system. In conclusion, this system permits wide-angle panoramic view of the surgical field. The contact lens neutralizes the optical irregularities of the corneal surface and allows improved visualization in eyes with irregular astigmatism induced by corneal scars. Excellent visualization is achieved in complex clinical situations such as miotic pupils, lenticular opacities, and in air-filled phakic eyes.

Does correcting astigmatism with toric lenses improve driving performance?

PubMed

Cox, Daniel J; Banton, Thomas; Record, Steven; Grabman, Jesse H; Hawkins, Ronald J

2015-04-01

Driving is a vision-based activity of daily living that impacts safety. Because visual disruption can compromise driving safety, contact lens wearers with astigmatism may pose a driving safety risk if they experience residual blur from spherical lenses that do not correct their astigmatism or if they experience blur from toric lenses that rotate excessively. Given that toric lens stabilization systems are continually improving, this preliminary study tested the hypothesis that astigmats wearing toric contact lenses, compared with spherical lenses, would exhibit better overall driving performance and driving-specific visual abilities. A within-subject, single-blind, crossover, randomized design was used to evaluate driving performance in 11 young adults with astigmatism (-0.75 to -1.75 diopters cylinder). Each participant drove a highly immersive, virtual reality driving simulator (210 degrees field of view) with (1) no correction, (2) spherical contact lens correction (ACUVUE MOIST), and (3) toric contact lens correction (ACUVUE MOIST for Astigmatism). Tactical driving skills such as steering, speed management, and braking, as well as operational driving abilities such as visual acuity, contrast sensitivity, and foot and arm reaction time, were quantified. There was a main effect for type of correction on driving performance (p = 0.05). Correction with toric lenses resulted in significantly safer tactical driving performance than no correction (p < 0.05), whereas correction with spherical lenses did not differ in driving safety from no correction (p = 0.118). Operational tests differentiated corrected from uncorrected performance for both spherical (p = 0.008) and toric (p = 0.011) lenses, but they were not sensitive enough to differentiate toric from spherical lens conditions. Given previous research showing that deficits in these tactical skills are predictive of future real-world collisions, these preliminary data suggest that correcting low to moderate astigmatism with toric lenses may be important to driving safety. Their merits relative to spherical lens correction require further investigation.

Microbial flora of tears of orthokeratology patients, and microbial contamination of contact lenses and contact lens accessories.

PubMed

Boost, Maureen V; Cho, Pauline

2005-06-01

The purpose of this study is to determine if there are changes in the ocular flora of overnight orthokeratology (ortho-k) patients, and the levels of contamination of their lenses and lens accessories, and to correlate compliance with levels of contamination. Normal ocular flora of 41 subjects was determined twice before commencing ortho-k lens wear by culture of the lower conjunctiva. Further specimens were collected on six follow-up visits after beginning lens wear, as were samples from their lenses, cases, and suction holders. A questionnaire on lens care was administered after the fifth visit. Three subjects provided conjunctival samples yielding Staphylococcus aureus on one occasion before lens wear, one being positive for this organism after beginning lens wear. Of 38 subjects yielding no growth or only normal eye flora before use, 28 remained free of ocular pathogens after beginning lens wear. Only four subjects had positive cultures on more than one occasion after lens wear. There was no significant difference in isolation levels of pathogens with lens wear (p = 0.423). Lens culture of 54% of subjects yielded no growth or normal flora only; lenses of 16 subjects yielded potential pathogens, including three subjects contaminated on more than one occasion. Lens isolates did not match the organisms transiently colonizing the eye. Lens case, the most frequently contaminated item, was associated with lens contamination (p < 0.001), the same organism being isolated from both items in 11 subjects. Lens suction holder was less frequently contaminated. Neither lens case nor suction holder contamination was associated with isolates from the eye. Reported good compliance correlated with lack of contamination in all but one subject. The most frequent breaches in the lens care protocol were failure to clean, disinfect, and replace the lens case. Ocular flora was not altered by ortho-k lens wear over an extended period, and patients remained free of infection. Contaminants identified were generally of a transient nature. Most patients had significant contamination of at least one item, most frequently the lens case. Lens case isolates were significantly associated with those from the lens. The majority of patients reporting good compliance had low or no contamination of their lenses and accessories.

Ocular physiology and comfort in neophyte subjects fitted with daily disposable silicone hydrogel contact lenses.

PubMed

Morgan, Philip B; Chamberlain, Paul; Moody, Kurt; Maldonado-Codina, Carole

2013-06-01

To evaluate the performance of a silicone hydrogel daily disposable lens in neophyte subjects over 12 months. Seventy four subjects with no previous contact lens experience were randomised to wear narafilcon A (1 DAY ACUVUE(®) TruEye™) lenses (LW group) or to wear no contact lenses (NLW group) for 12 months. Biomicroscopy (performed by a masked investigator), visual acuity and subjective response scores were recorded at an initial visit and six follow-up visits, in addition to lens fit and surface evaluation for the LW group. Comfort was recorded with SMS messaging. Fifteen of the LW group discontinued before the end of the study, compared with six of the NLW group. Measured visual acuity was about half a line better for the NLW group as these subjects were provided with their full sphero-cylindrical over-refraction, compared to the LW group in their best spherical corrected contact lenses; subjective scores for vision were similar for the two groups. Bulbar conjunctival hyperaemia, limbal hyperaemia, corneal staining, conjunctival staining and papillary conjunctivitis were clinically equivalent for the two groups whereas conjunctival staining was higher in the LW group. Comfort scores assessed by SMS were equivalent for the LW and NLW groups; there was a measurable improvement in comfort during the first month of wear for the LW group. This work has demonstrated that modern soft lenses (narafilcon A daily disposable silicone hydrogel lenses) offer an excellent, comfortable form of vision correction, and are able to exhibit minimal alterations to ocular physiology. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

The role of type III secretion system and lens material on adhesion of Pseudomonas aeruginosa to contact lenses.

PubMed

Shen, Elizabeth P; Tsay, Ruey-Yug; Chia, Jean-San; Wu, Semon; Lee, Jing-Wen; Hu, Fung-Rong

2012-09-21

To determine the distribution of invasive and cytotoxic genotypes among ocular isolates of P. aeruginosa and investigate the influence of the type III secretion system (T3SS) on adhesion to conventional, cosmetic, and silicone hydrogel contact lenses (CL). Clinical isolates from 2001 to 2010 were analyzed by multiplex PCR for exoS, exoU, and exoT genes. Bacterial adhesion to etafilcon, nelfilcon (gray colored), balafilcon, and galyfilcon CL with or without artificial tear fluid (ATF) incubation were compared. Surface characteristics were determined with scanning electron microscopy (SEM). Among 87 total isolates, 64 strains were from microbial keratitis cases. CL-related microbial keratitis (CLMK) isolates were mostly of the cytotoxic genotype (expressing exoU) (P = 0.002). No significant differences were found in bacterial adhesion to all types of CL between the genotypes under T3SS-inducing conditions. A trend for least bacterial adhesion of galyfilcon compared to the other CL was noted for both genotypes. Needle complex pscC mutants adhered less to all materials than the wild type (P < 0.05), indicating a role of the T3SS in contact lens adhesion. ATF-incubated CL had significantly more bacterial adhesion (P < 0.05). SEM showed most of the bacteria adhering on CL surfaces. CLMK isolates were mostly of cytotoxic genotype. Different genotypes did not significantly differ in its adhesion to various CL. T3SS and other adhesins are involved in bacteria-contact lens adhesion through complex interactions. Contact lens materials may also play an important role in the adherence of both genotypes of P. aeruginosa.

A novel method to predict the dry eye symptoms in new contact lens wearers.

PubMed

Pult, Heiko; Murphy, Paul J; Purslow, Christine

2009-09-01

Lid wiper epitheliopathy (LWE) and lid parallel conjunctival folds (LIPCOF) give moderate prediction levels for dryness symptoms in experienced contact lens (CL) wearers. This study investigated whether a combination of LWE and LIPCOF plus other tear film tests and subjective evaluation before contact lens fitting was better able to predict CL-induced dry eye (CLIDE) symptoms. Tear meniscus height, non-invasive break-up time (NIBUT), ocular hyperaemia, LIPCOF, phenol red thread test, corneal and conjunctival staining, and LWE of the right eye of 33 new soft CL wearers (12 males, 21 females, median age = 30.5 years; range = 19 to 44) were assessed in a prospective 2-mo longitudinal study. Symptoms were evaluated by the Ocular Surface Disease Index (OSDI) and subjects were grouped according to their response in the Contact Lens Dry Eye Questionnaire (CLDEQ) during the study (20 symptomatic and 13 asymptomatic). The subjects were fitted with vifilcon A and senofilcon A lenses for a 2-week period, consecutively. Limbal hyperaemia (repeated measures analysis of variance; p < 0.05) and LWE (Friedman; p < 0.004) increased significantly during the study but not LIPCOF (p > or = 0.318; temporal, nasal, and Sum), bulbar hyperaemia (p = 0.432), staining (p > or = 0.060), OSDI (p = 0.126), or CLDEQ (p = 0.317, kappa = 0.279). Limbal hyperaemia significantly decreased in senofilcon A lenses. Wearing comfort among symptomatics was significantly better with senofilcon A (p = 0.005). At the enrolment visit, the subjects who became symptomatic exhibited significantly decreased NIBUT and increased LIPCOF and OSDI (range, p < 0.027). The best test combination to predict CLIDE (logistic regression analyses) was LIPCOF Sum plus NIBUT and OSDI, (positive predictive value = 87% and accuracy = 91%). LIPCOF, NIBUT, and OSDI are significant discriminators for CLIDE in new CL wearers compared with hyperaemia, tear meniscus height, phenol red thread test, staining, and LWE. The best test combination is NIBUT plus LIPCOF Sum and OSDI (named the Contact-Lens-Predicting-Test).

Evaluation of Protamine as a Disinfectant for Contact Lenses.

PubMed

Bandara, Mahesh K; Masoudi, Simin; Zhu, Hua; Bandara, Rani; Willcox, Mark D P

2016-11-01

To investigate the ability of protamine, alone or in combination with other antimicrobial agents, to kill bacteria and fungi associated with contact lens-related keratitis. The International Organization for Standardization 14729:2001 procedure was used to test the antimicrobial activity of solutions of protamine (23-228 μM) with and without polyhexamethylene biguanide (PHMB) and ethylenediamine tetra-acetic acid (EDTA). The recommended ISO panel of microbes along with six clinical isolates was tested. The effect of increasing sodium chloride concentration on the antimicrobial activity was also assessed. The cytotoxicity of the final protamine/EDTA/PHMB solution was measured using ISO 10993-5 standard assays. Protamine gave a dose-dependent antimicrobial effect, with the highest effect for most strains being at 228 μM (≥6 log reductions of viable bacteria and ≥1 log reduction of viable fungi). Addition of EDTA and PHMB increased the antimicrobial effect for all strains except Pseudomonas aeruginosa ATCC6538, which had optimum activity (≥6 log inhibition) even in protamine alone. The optimum antimicrobial activity of all microbes was achieved in 0.2% sodium chloride, but even in 0.8% sodium chloride, the activity met or exceeded the ISO standard (>3 log reductions for bacteria and >1 log reduction for fungi). None of the formulations was cytotoxic to mammalian cells. This study highlights the potential for protamine to be used for the development of effective multipurpose disinfection solutions. Further investigations such as stability, compatibility with contact lenses, and in vivo toxicity are warranted.

Contact-eutectic-lens fabrication technique

NASA Technical Reports Server (NTRS)

Allen, F. G.; Yue, A. S.; Yu, J. G.

1975-01-01

Method enables use of crystal or semiconductor materials with selective spectral-response characteristics (ultraviolet, visible, or infrared wavelengths) in fabrication of contact lenses, reading glasses, and photographic processing equipment.

16 CFR 315.2 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-01-01

... contact lens fitting. Ophthalmic goods are contact lenses, eyeglasses, or any component of eyeglasses. Ophthalmic services are the measuring, fitting, and adjusting of ophthalmic goods subsequent to an eye...

16 CFR 315.2 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... contact lens fitting. Ophthalmic goods are contact lenses, eyeglasses, or any component of eyeglasses. Ophthalmic services are the measuring, fitting, and adjusting of ophthalmic goods subsequent to an eye...

16 CFR 315.2 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... contact lens fitting. Ophthalmic goods are contact lenses, eyeglasses, or any component of eyeglasses. Ophthalmic services are the measuring, fitting, and adjusting of ophthalmic goods subsequent to an eye...

16 CFR 315.2 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... contact lens fitting. Ophthalmic goods are contact lenses, eyeglasses, or any component of eyeglasses. Ophthalmic services are the measuring, fitting, and adjusting of ophthalmic goods subsequent to an eye...

16 CFR 315.2 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... contact lens fitting. Ophthalmic goods are contact lenses, eyeglasses, or any component of eyeglasses. Ophthalmic services are the measuring, fitting, and adjusting of ophthalmic goods subsequent to an eye...

Prevalence of ocular surface symptoms, signs, and uncomfortable hours of wear in contact lens wearers: the effect of refitting with daily-wear silicone hydrogel lenses (senofilcon a).

PubMed

Riley, Colleen; Young, Graeme; Chalmers, Robin

2006-12-01

Many soft contact lens wearers have symptoms or signs that compromise successful lens wear. This study estimated the prevalence of problems in current wearers of soft contact lenses and tested the effect of refitting patients with senofilcon A silicone hydrogel lenses (ACUVUE Oasys). Prevalence was estimated from 1,092 current lens wearers for frequent or constant discomfort or dryness, at least 2 hours of uncomfortable wear, at least grade 2 limbal or bulbar hyperemia (0-4), or at least grade 3 corneal staining (0-15). In the second part of the study, 112 of the 564 wearers classified as problem patients were refitted with senofilcon A lenses and reassessed 2 weeks later. Fifty-two percent (564 of 1,092) had some qualifying criteria, with dryness reported by 23%, discomfort by 13%, and at least 2 hours of uncomfortable wear by 27%. Six percent of subjects had qualifying limbal hyperemia; 10% had bulbar hyperemia; and 12% had corneal staining. After refitting 112 problem patients, 75% had less dryness; 88% had better comfort (P<0.0001 each); and 76% had fewer uncomfortable hours of wear (P=0.004). Although the average wearing time was unchanged, comfortable wearing time increased significantly (10.4 to 11.6 hours) (P=0.004). All (35 of 35) eyes with qualifying limbal hyperemia before the refit also improved (P<0.0001), as did 80% (40 of 50) of those with bulbar hyperemia (P<0.0001) and 76% (26 of 34) of those with corneal staining (P=0.005). Most soft lens wearers encounter clinically significant signs or symptoms with their current contact lenses. Refitting with new-generation silicone hydrogel lenses (senofilcon A) can alleviate some of these common problems.

To wear or not to wear: current contact lens use in the Royal Canadian Mounted Police.

PubMed

Wells, G A; Brown, J J; Casson, E J; Easterbrook, M; Trottier, A J

1997-04-01

The Canadian Ophthalmological Society was asked by the Royal Canadian Mounted Police (RCMP) and the Canadian Human Rights Commission to render an opinion on the acceptability of contact lenses as a reasonable accommodation to the uncorrected visual acuity standard. Survey by mailed questionnaire. Canada. All RCMP general duty constables with a visual acuity code of V3, V4, V5 or V6 (n = 348) and a random sample of approximately 25% of the constables with an acuity code of V2 (n = 809). Of the 1040 questionnaires returned, 1037 were usable (final response rate 89.6%). Of the 1037 respondents 316 were in the V3 to V6 group and 721 were in the V2 group. Reported frequency of problems with spectacles or contact lenses, weighted according to sampling fraction. A total of 934 respondents indicated that they used some form of visual acuity correction while on duty; of the 934, 360 reported that they wore contact lenses at least some of the time. Approximately 75% of the spectacle wearers reported having to remove their spectacles because of fogging or rain. Although contact lens dislogement or fogging (21.2%) was less frequent than spectacle dislogement (59.2%), 35.4% of the contact lens wearers reported that they were unable to wear their lenses because of irritation on at least one occasion in the previous 2 years; the median length of time was 3.14 days. When the additional amount of time due to other causes is factored in, it is clear that contact lens users wear spectacles for substantial periods while on duty. Not only are RCMP general duty constables who usually wear contact lenses likely to have to wear spectacles at some time, but it is also possible that they will have to remove their spectacles and function in an uncorrected state in critical situations. Thus, altering the current standard to allow the use of contact lenses as a reasonable accommodation would not ensure effective and safe job performance.