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Kramer, Elise G; Boshnick, Edward L
This case report aims to explore the use of scleral lenses for the treatment of ocular and visual complications in an adult patient presenting with post-LASIK (Laser-Assisted in situ Keratomileusis) ectasia in both eyes with cross-linking in the right eye and intrastromal corneal ring segments (ICRS; Intacs, Addition Technology, Fremont, CA) in the left eye. Following a comprehensive eye exam and specific testing for contact lens fitting, scleral lenses were fitted with success in both eyes and dispensed. Due to progressive fibrosis and neovascularization of the inferior ICRS in the left eye, the inferior ICRS was removed and scleral lenses were refit with success. Prescribed scleral lenses helped the patient achieve optimal visual correction (20/20) as well as ocular protection of the cornea. Post-LASIK ectasia is a common finding among contact lens specialists today. When ICRS surgery is involved, the fitting of contact lenses may become more challenging. Scleral lenses offer a unique way of addressing many issues raised in this case report including corneal neovascularization and ectasia. This lens modality may be considered for any other case involving irregular corneal curvature following surgery resulting in reduced visual acuity. Copyright © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
speculate why no medical eye problems occurred. There are two possible reasons. One is the degree of patient education and adherence to instructions...Management of this situation can only be accomplished through continuing patient education . Contact lens wearers should also be aware of the problem
The prevalence of myopia has been steadily rising, with 28 per cent of the global population said to be affected in 2010 and to rise to affect nearly 50 per cent by 2050. Increasing levels of myopia increase the risk of vision impairment and in particular, high myopia is associated with the risk of serious and permanent visual disability due to associated sight-threatening complications. To stem the burden associated with higher levels of myopia, there are efforts to slow the progression of myopia, and several optical and pharmaceutical strategies have been found useful in slowing myopia to varying degrees. More recently, numerous multifocal soft contact lenses and extended depth of focus soft contact lenses (collectively referred to as myopia control contact lenses) were found effective in slowing myopia. As opposed to overnight orthokeratology, myopia control contact lenses are worn during the day and the hypotheses proposed to explain the efficacy of these lenses are generally based on the premise that the stimulus for eye growth is a defocused retinal image with hyperopic blur either centrally or peripherally. Although the individual power profiles of the lenses vary, the contact lens generally incorporates 'positive power' to reduce the hyperopic blur and/or impose myopic defocus or in the case of the extended depth of focus lens, has a power profile designed to optimise retinal image quality for points on or in front of the retina. The use of soft contact lenses as a platform for myopia control offers an exciting and effective avenue to manage myopia but there is a need for further research on issues such as the mechanism underlying control of myopia, improving efficacy with lenses, and understanding rebound on discontinuation. More significantly, although contact lenses are generally safe and improve quality of life in older children, one of the major challenges for improved uptake and acceptance of contact lenses centres on the perceived risk of
Muntz, Alex; Subbaraman, Lakshman N.; Sorbara, Luigina; Jones, Lyndon
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
Arora, R; Gupta, S; Taneja, M; Raina, U K; Mehta, D K
To evaluate the therapeutic efficacy of disposable contact lenses in management of complications after keratoplasty. Twenty-eight patients with various post keratoplasty complications were fit with disposable contact lenses (45% Vifilcon A and 55% water content). Indications for lens use included persistent epithelial defects, wound leak, graft edema, dry eye and protection of normal corneal epithelium. Success was obtained with the therapeutic use of disposable lenses in 20 of the 28 cases. The best results were seen in maintenance and restoration of healthy ocular surface and small wound leaks. Stromal graft edema with no epithelial involvement was the major area of therapeutic failure. Disposable contact lenses are an attractive low cost option in the management of complications after keratoplasty. They are particularly useful in maintaining a healthy ocular surface, providing symptomatic relief and avoiding resurgery in patients with small wound leaks.
Krysztofiak, Katarzyna; Ciężar, Kamila; Kościński, Mikołaj
Daily disposable contact lenses are gaining in popularity among practitioners and wearers for the improved ocular health and subjective outcomes they offer. Recently a novel daily disposable contact lens material with water gradient technology was introduced. Delefilcon A lenses consist of a 33% water content silicone hydrogel core and an outer hydrogel layer which is totally free of silicone and contains 80% water. The aim of the present study was to confirm the layered structure of delefilcon A contact lenses. Thickness of hydrogel coating on the silicone hydrogel core was assessed using Raman spectroscopy. To investigate the layered structure of the material, depth spectra of the lenses were recorded. The results obtained suggest that at about 6 μm a boundary between the hydrogel layer and silicone hydrogel core exists, which is in good agreement with the manufacturer's data. Data collected in this experiment confirm a water gradient at the delefilcon A lens surface.
Dutta, Debarun; Willcox, Mark
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
Dutta, Debarun; Cole, Nerida; Willcox, Mark
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.
Wahl, Siegfried; Fornoff, Luise; Ochakovski, G Alex; Ohlendorf, Arne
The study investigated the effect of the design of multifocal contact lenses on the sensitivity to contrast and disability glare. Contrast sensitivity was measured in 16 young adults (mean age: 25.5±2.5years) at a distance of 2m under two conditions: no-glare and glare. Two designs (Center Near and Center Distance) of the Biofinity soft contact lens were used to simulate correction for presbyopes, while a correction with single vision trial lenses and contact lenses acted as controls. The design of the used multifocal contact lenses had a significant influence on the log area under the curve of the contrast sensitivity function (AUC-CSF). Compared to the spectacle lens correction, the AUC-CSF was significantly reduced, in case CS was measured with the Center Near design lens, under the no-glare (p<0.001) and the glare condition (p: p<0.001). In case of the Center Distance design contact lens, the AUC-CSF was significantly smaller in case CS was tested under glare (p=0.001). Disability glare (DG) was depending on the spatial frequency and the design of the multifocal lens, while the Center Distance design produced higher amounts of DG (p<0.001), compared to the other used corrections. The optical design of a multifocal contact lenses has a significant impact on the contrast sensitivity as well as the disability glare. In order to dispense the best correction in terms of contact lenses, the sensitivity to contrast under no-glare and glare conditions should be tested a medium spatial frequencies. Copyright © 2017. Published by Elsevier Ltd.
Koos, D; Koos, M J
The indications of contact lens adaptation in optical purpose are widely large, starting, with refractive errors [correction of vices], unilateral and bilateral aphakia, myopia, anisometropia and astigmatism, together with the use of contact lens in esthetic purpose. We have been presented the adaptation techniques, the supervise, and maintenance of contact lens.
Donshik, P; Weinstock, F J; Wechsler, S; Asbell, P; Atwood, J; Davis, H; Farkas, B; Farris, R L; Gruber, E; Hartstein, J
Nine ophthalmologists and nine optometrists conducted a premarket study of the Acuvue disposable contact lens manufactured by Vistakon, Inc. Of the 812 patients offered the lens, 733 accepted it and were enrolled in the study. These patients were fitted with the lens and followed for a period of 8 months. Over 98% of these patients had 20/25 or better vision on initial fitting; and subjective ratings of lens comfort were very good. Only 3.7% (27 of 733) discontinued wearing their lenses during the study period. Thirty-four patients (5.6%) experienced a problem while wearing their contact lenses.
Chan, Ka Yin; Cho, Pauline; Boost, Maureen
To investigate whether cosmetic contact lenses (CCL) with surface pigments affect microbial adherence. Fifteen brands of CCL were purchased from optical, non-optical retail outlets, and via the Internet. A standardized rub-off test was performed on each CCL (five lenses per brand) to confirm the location of the pigments. The rub-off test comprised gentle rubbing on the surfaces of each CCL with wetted cotton buds for a maximum of 20 rubs per surface. A new set of CCL (five lenses per brand) were incubated in Pseudomonas aeruginosa overnight. Viable counts of adhered bacteria were determined by the number of colony-forming units (CFU) on agar media on each lens. The adherence of P. aeruginosa as well as Staphylococcus aureus and Serratia marcescens to three brands of CCL (A-C) (five lenses per brand) were also compared to their adherences on their clear counterparts. Only two of the 15 brands of CCL tested (brands B and C) had pigments that did not detach with the rub-off test. The remaining 13 brands of CCL all failed the rub-off test and these lenses showed higher P. aeruginosa adherence (8.7 × 10(5)-1.9 × 10(6) CFU/lens). Brands B and C lenses showed at least six times less bacterial adhesion than the other 13 brands. Compared to their clear counterparts, bacterial adherence to brands B and C lenses did not differ significantly, whereas brand A lenses showed significantly higher adherence. Surface pigments on CCL resulted in significantly higher bacterial adherence. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
... Consumer Updates Halloween Safety: Costumes, Candy, and Colored Contact Lenses Share Tweet Linkedin Pin it More sharing ... or witch, poor costume choices—including decorative (colored) contact lenses and flammable costumes—and face paint allergies ...
... Home For Consumers Consumer Updates 'Colored' and Decorative Contact Lenses: A Prescription Is A Must Share Tweet ... appropriate follow-up care.” Where NOT to Buy Contact Lenses FDA is aware that many places illegally ...
Young, G; Allsopp, G; Inglis, A; Watson, S
A short-term clinical study was undertaken to compare and evaluate the fit and clinical behaviour of eight disposable hydrogel contact lenses. Thirty subjects were enrolled in a 1-day, randomised, double-masked study. The lenses compared were Vistakon Acuvue (8.80), Vistakon Surevue (8.80), Aspect Frequency-55, Bausch & Lomb Medalist (SeeQuence 2), Ciba Focus (8.90), Lunelle Rythmic, Pilkington Barnes Hind Precision-Wand Wesley Jessen Freshlook. Three of the eight designs, Acuvue (86.7%), Precision-UV (86.7%) and Frequency-55 (90%), achieved relatively high levels of fitting success. The Rythmic lenses achieved the lowest success rate (70%) showing significantly greater downward decentration than the other designs. Although all the lenses were designed to fit a wide variety of eyes, they exhibited widely varying fitting characteristics. Some were more successful than others. The study shows that it is necessary for practitioners to utilise a range of lens designs in order to fit satisfactorily the typical contact lens population.
Łabuz, Grzegorz; López-Gil, Norberto; van den Berg, Thomas J T P; Vargas-Martín, Fernando
Multifocal contact lenses have been growing in popularity as a modality to correct presbyopic eyes, although visual side effects such as disability glare have been reported. The objective of this study was to investigate the effect of multifocal contact lenses on disability glare by means of ocular straylight. A prospective randomized, comparative study was performed that included 16 subjects free of ocular pathology. Straylight was measured using a commercial straylight meter with the natural and dilated pupil. Participants were fitted with Proclear Multifocal (Distance/Near), ACUVUE Oasys for Presbyopia, and Air Optix Aqua Multifocal randomized to the left or right eye. Straylight measurements were repeated with the contact lens in situ after the pupil dilation. Results obtained with the dilated pupil without contact lens acted as a control. Diameter of the natural and dilated pupil was 2.87 ± 0.40 mm and 7.45 ± 0.86 mm, respectively (P < .001). After pupil dilation, straylight increased from 0.92 ± 0.13 log(s) to 1.04 ± 0.11 log(s) (P < .001). Of the four studied lenses, a significant difference was only found between Air Optix and the control group (P = .006). The latter showed also slightly increased light scatter. A difference in measured straylight was found between the studied multifocal lenses. The observed variability and the straylight-pupil size dependency should be taken into account to avoid elevated straylight in multifocal contact lens wearers. The reason for the observed differences in straylight must be the subject of future studies.
Bailey, J.; Kaur, S.; Morgan, P. B.; Gleeson, H. F.; Clamp, J. H.; Jones, J. C.
Switchable liquid crystal contact lenses with electrically controllable focal powers have previously been investigated as an alternative to bifocal contact lenses and spectacles for the correction of presbyopia. The simplest lens design uses a meniscus shaped cavity within the lens to contain the liquid crystal. The design of such a lens is considered in detail, including the nematic alignment and electrodes materials. The organic transparent conductor PEDOT:PSS was used as both electrode and planar alignment. Four different configurations are considered, using both planar and homeotropic orientations with either homogenous or axial alignment. Controllable switching of the focal power was demonstrated for each mode and focal power changes of up to ΔP = 3.3 ± 0.2 D achieved. Such lens designs offer significant potential for a novel form of correction for this common visual problem.
Josephson, J E; Caffery, B E; Campbell, I; Slomovic, A R
We compared a disposable extended wear contact lens modality with conventional extended wear over a 6-week period. To do so, we refit 31 patients who had successfully worn conventional extended wear contact lenses for more than 1 year. One eye was fit with the AcuvueR disposable contact lens, and a new extended wear lens of the type the patient had been wearing was placed on the other eye. At weekly intervals the disposable lens was discarded and a new disposable lens inserted. At the same time, the conventional lens on the fellow eye was cleaned, disinfected, and reinserted. After 6 weeks the ocular response, subjective impressions, and condition of the lenses in the two eyes were compared. Both lenses were then cultured. Three subjects had to discontinue disposable lens wear because of adverse reactions to trapped cellular debris and corneal microcysts. Although the results were not statistically significant, the Acuvue lens appeared to perform better than or equal to the conventional lens in biomicroscopic observation, visual acuity measurement, and subjective patient preference. Eighty-seven percent of patients preferred to continue with the disposable system. There were no differences found in the type or degree of microbial contamination of the lenses.
... Updates What To Know If Your Child Wants Contact Lenses Share Tweet Linkedin Pin it More sharing ... removed at the first hint of a problem. Contact Lens Risks And Safety Tips Kids and contact ...
hydrogel contact lenses . NSMRL Report (in press). 9. U.S. Navy Diving Manual. Vol 1. Air Diving, Washington, D.C.: Navy Department, June 1985...gg, ^-; Pr v^yJ:-- -^j~£^ z<_^ "SSSES MEDIGÄL asefeHs a»s.^r,--. - «$ i T RIGID GAS PERMEABLE CONTACT LENSES IN HYPERBARIC...This creates the problem of storing their spectacles while diving and finding them again when they surface. Contact lenses could solve this
Bhatia, R P; Panday, Kshama; Srivastava, Rashmi; Indolia, Hitendra Singh
We examined the role of tear secretion on contact lens water content during selection. Tear secretion was estimated using Schirmer's tests. High-water-content contact lenses compromised the tear film more than low-water-content contact lenses, hence they should not be advised in low or marginal Schirmer's test cases.
While gravity has its advantages in keeping us balanced and grounded here on Earth, scientists often find that they are at a disadvantage when trying to conduct research under its powerful, pulling influence. In these instances, the scientists prefer performing their studies in the weightless atmosphere of microgravity, where gravity is greatly reduced and solids, liquids, and gases behave differently. In 1993, Paragon Vision Sciences, Inc., of Mesa, Arizona, participated in a research project with NASA's Langley Research Center to perfect a process for developing contact lenses. The project called for three experiments that would fly onboard the Space Shuttle over the course of three separate missions, from 1993 to 1996. By unleashing contact lens materials to the microgravity settings of space, scientists from NASA and Paragon hoped to better understand how polymers - large molecules that make up plastics - are formed.
Li, Lim; Moody, Kurt; Tan, Donald T H; Yew, Khoo Chong; Ming, Por Yong; Long, Quah Boon
Previous studies in the United States have evaluated the benefits of soft contact lenses (CLs) in 8- to 12-year-old children and 13- to 17-year-old teens. This study was undertaken in Singapore and evaluated the safety, efficacy, and physiologic performance of daily disposable soft lenses in a population of children. In this open-label, bilateral, 3-month dispensing study, 59 children (8-11 years) were fit with etafilcon A spherical or toric daily disposable lenses (1-DAY ACUVUE or 1-DAY ACUVUE for ASTIGMATISM, Vistakon, Jacksonville, FL). All subjects were neophytes requiring visual correction in both eyes. The refractive inclusion criteria were plano to -9.00 diopter (D) with astigmatism of < or =2.00DC in both eyes, or hyperopia of +0.50 to +6.00D with astigmatism of 0.75D or less. The subjects underwent follow-up evaluations, which included a questionnaire for parents and subjects, at 1 week, 1 month, and 3 months. Of the 59 subjects enrolled, 53 (90%) completed the study successfully. Six subjects were discontinued because of lens handling difficulties (four), unacceptable lens fit (one), and an adverse event (one). Adverse events were reported in three subjects, including the discontinuation, and in each case were due to a chalazion. Overall vision quality, overall comfort, and end-of-day comfort were graded significantly better at each of the follow-up visits compared with baseline with spectacles (P< or =0.0001). Both handling and reported symptoms improved during the course of the study. The questionnaire results indicated that most of both parents and subjects preferred CLs to spectacles across a wide variety of aspects including vision, comfort, handling, and appearance. Significantly, more limbal and bulbar hyperemia was noted at follow-up visits than at baseline (P=0.0001); however, no instances of hyperemia greater than grade 2 were noted at any visit. Significantly, more corneal staining was also noted at the 1- and 3-month follow-up visits than at
Moschos, Marilita M.; Nitoda, Eirini; Georgoudis, Panagiotis; Balidis, Miltos; Karageorgiadis, Eleftherios; Kozeis, Nikos
Background: Keratoconus is a chronic, bilateral, usuallly asymmetrical, non-inflammatory, ectatic disorder, being characterized by progressive steepening, thinning and apical scarring of the cornea. Initially, the patient is asymptomatic, but the visual acuity gradually decreases, resulting in significant vision loss due to the development of irregular astigmatism, myopia, corneal thinning and scarring. The classic treatment of visual rehabilitation in keratoconus is based on spectacles and contact lenses (CLs). Objective: To summarize the types of CLs used in the treatment of keratoconus. This is literature review of several important published articles focusing on the visual rehabilitation in keratoconus with CLs. Method: Gas permeable (GP) CLs have been found to achieve better best corrected visual acuity than spectacles, eliminating 3rd-order coma root-mean-square (RMS) error, 3rd-order RMS, and higher-order RMS. However, they have implicated in reduction of corneal basal epithelial cell and anterior stromal keratocyte densities. Soft CLs seem to provide greater comfort and lower cost, but the low oxygen permeability (if the lens is not a silicone hydrogel), and the inability to mask moderate to severe irregular astigmatism are the main disadvantages of them. On the other hand, scleral CLs ensure stable platforms, which eliminate high-order aberrations and provide good centration and visual acuity. Their main disadvantages include the difficulties in application and removal of these lenses along with corneal flattening and swelling. Result: The modern hybrid CLs are indicated in cases of poor centration, poor stability or intolerance with GP lenses. Finally, piggyback CL systems effectively ameliorate visual acuity, but they have been related to corneal neovascularization and giant papillary conjunctivitis. Conclusion: CLs seem to rehabilitate visual performance, diminishing the power of the cylinder and the high-order aberrations. The final choice of CLs is
Qu, Xiao-Mei; Dai, Jin-Hui; Jiang, Zhen-Ying; Qian, Yi-Feng
To compare the clinical performance of two types of silicon hydrogel contact lenses used as bandage lenses after LASEK surgery. A prospective, double-masked study was conducted on 42 eyes of 21 patients who received binocular LASEK surgeries. The interocular difference in spherical equivalent power was less than -1.50D. Patients were randomly assigned to wear Galyfilcon A (Lens A) bandage contact lens in one eye and Balafilcon A (Lens B) in the fellow eye after the surgery. The responses to a subjective questionnaire on comfort of wearing, corneal epithelial status, conjunctival hyperemia, limbal neovascularization, lens fitting and contact lens debris were assessed 1 and 5 days postoperatively. Corneal endothelium was assessed before and 5 days after the surgery upon bandage lens removal. There was no difference between the two groups in terms of conjunctival hyperemia, limbal neovascularization, contact lens fitting, corneal epithelial status, corneal endothelium cell density (CD) and endothelium cell size (CS) at any postoperative visit. Complaints of discomfort, including foreign body sensation, pain and intolerance were statistically more among Lens B wearers at any postoperative visit (P<0.05). Lens B appeared to attract much more debris than Lens A at the 5-day post-operative follow-up visit (P<0.01). The two types of silicon hydrogel lenses investigated in this study demonstrated similar clinical performance in terms of corneal responses and lens fitting. However, Lens A showed a better performance in terms of comfort of wearing and deposit resistance.
Lipener, César; Ray, Camila Baracat Mendina
The proper maintenance of contact lenses is crucial for their success and to maintain the continuity of their use. Many patients abandon the use of their lenses due to problems that could be solved with relatively simple treatments. The misuse of lenses, coupled with poor adjustment, contamination, eye disease and environmental factors may increase the number of corneal infections through the proliferation of microorganisms. This article aims to provide contact lens care and maintenance updates.
Hart, D E; DePaolis, M; Ratner, B D; Mateo, N B
We used electron spectroscopy for chemical analysis (ESCA) to examine the surface chemistry of polymacon, tefilcon, and bufilcon hydrogel contact lenses. Worn and unworn water-cleaned and surfactant-cleaned lenses were compared. The surface chemistry of unworn lenses, which were used as controls, consisted of approximately 70% carbon, 25% oxygen, and < 10% other elements (i.e., silicon, sulfur, sodium, nitrogen, and zinc). In general, surfactant cleaning removed silicon contamination, but left a residue containing sulfur and zinc. The increase in the nitrogen/carbon (N/C) ratio for worn bufilcon and polymacon lenses was significantly greater than the N/C ratio for unworn bufilcon and polymacon lenses. As a group the worn ionic lenses (bufilcon) showed a greater N/C ratio than the worn nonionic lenses (polymacon, tefilcon). The nitrogen that appears on all worn lenses probably represents adherent as well as adsorbed surface proteins. The highest N/C ratios were found on a pair of pathologically deposited lenses and on the lens with the longest wearing time (2 years). For the bufilcon and polymacon lenses, the differences observed in the ESCA data for the unworn and worn lenses suggest that contact lenses begin interacting with the tear film within 1 minute (the shortest wearing time in this study).
Uçakhan, Omür O; Bayraktutar, Betül
To evaluate the safety, efficacy, and on-eye performance of KeraSoft 3 contact lenses (UltraVision) in ectatic corneal diseases. The charts of patients who were fit with KeraSoft 3 were reviewed. The reason for KeraSoft 3 lens fit, the number of trial lenses required for ideal fit, centration, movement, and stabilization of the contact lens, uncorrected, spectacle-corrected, and contact lens-corrected visual acuities, slitlamp biomicroscopy findings, patient comfort, and daily duration of contact lens wear were evaluated. Seventy eyes of 40 patients were fit with the KeraSoft 3 lens. Indications included rigid gas permeable (RGP) lens intolerance in 41 eyes of 24 patients (58.5%), patients' desire to use soft contact lenses in 26 eyes of 14 patients (37.1%), and proud nebula in 3 eyes of 2 patients (4.4%). The number of trial lenses required for ideal fit was 1.2±0.4 lenses. Eleven patients (20 eyes, 29%) never purchased the contact lens, 15 patients (26 eyes, 37%) discontinued after purchasing, and 14 patients (24 eyes, 34%) continued successfully wearing their lenses. In the latter group, the visual acuity improved significantly (P<0.05) and no adverse events were encountered during the mean follow-up period of 10.0±9.8 months. At the last follow-up examination, patients rated comfort and visual acuity with their contact lenses as "very good" to "excellent," with a desire to continue wearing them. In refractive correction of corneal ectasia, KeraSoft 3 contact lenses seem to be a good alternative to RGP lenses before more sophisticated lenses such as hybrid or scleral lenses are tried.
Wu, Yvonne T; Tran, Jess; Truong, Michelle; Harmis, Najat; Zhu, Hua; Stapleton, Fiona
Wearing goggles over contact lenses while swimming is often recommended by eye care professionals. Limited data are available to assess this recommendation. The purpose of this study was to examine whether wearing goggles while swimming limits bacterial colonization on contact lenses and whether the type of lens worn affects contamination rates. Twenty-three subjects underwent two swimming sessions at an ocean (salt water) pool (Maroubra beach Rock Pool, Sydney, Australia). Silicone hydrogel (Ciba Focus Night and Day) or hydrogel lenses (Ciba Focus Daily) were inserted into subjects' eyes before 30 min of swimming sessions, and subjects used modified goggles to mimic goggled and non-goggled conditions. At the end of each session, lenses were collected for microbial investigation. Viable bacterial colonies were classified as gram positive and gram negative and enumerated. The level of bacterial colonization on contact lenses between goggled and non-goggled conditions and between the two lens materials were compared. The range of colony forming units recovered from goggled lenses were 0 to 930 compared with 0 to 1210 on non-goggled lenses. The majority of subjects (16/23) had more microorganisms in the non-goggled condition than when wearing goggles (p = 0.03). Gram negative organisms were found in three non-goggled lenses. No significant difference was shown in the number of bacteria isolated from silicone hydrogel and hydrogel lenses (p > 0.6) irrespective of wearing goggles. Water samples had consistently higher numbers of bacterial counts than those adhered to the lenses; however, no association was found between the number of bacteria in the water sample and those found on the contact lenses. Consistently, fewer bacterial colonies were found on the goggled contact lens, thus suggesting goggles offer some protection against bacterial colonization of contact lenses while swimming. These data would support the recommendation encouraging lens wearers to use goggles
Razmjoo, Hasan; Abdi, Elham; Atashkadi, Sayna; Reza, Akhlaghi M; Reza, Peyman A; Akbari, Mojtaba
Silicon hydrogel bandage contact lenses are used to enhance epithelial healing, control surface-generated pain, and prevent epithelial erosions after refractive surgery. Considering the importance of faster reepithelialization in preventing complications of photorefractive keratectomy (PRK) and the fact that the features and specifications of these commercially-available lenses are different and their performance as a postoperative bandage lenses would be different also, the aim of this study was comparison the efficacy of senofilcon A and lotrafilcon A after PRK. In this prospective study, 44 patients with PRK in both eyes randomly received a silicon hydrogel contact lens of senofilcon A in one eye and lotrafilcon A in other eye. Then the epithelial defect size, visual acuity and subjective level of pain and discomfort were measured for both eyes and compared on day 1, 3 and 5 postoperatively. There was no statistical difference in rate of reepithelialization between senofilcon A and lotrafilcon A (P > 0.05). The mean pain and discomfort index was significantly lower in eyes with senofilcon A (P < 0.05). The mean subjective visual scores were similar with both bandage contact lenses (BCLs) (P > 0.05). Silicon hydrogel BCLs are safe and effective for corneal reepithelialization and have great therapeutic outcome on visual outcomes after PRK. But, senofilcon A had better effect on postoperative pain and discomfort which made it superior than lotrafilcon A. However for more conclusive results, it is recommended to study larger sample size with evaluation the possible factors responsible for the obtained findings regarding postoperative pain and discomfort.
Razmjoo, Hasan; Abdi, Elham; Atashkadi, Sayna; Reza, Akhlaghi M; Reza, Peyman A; Akbari, Mojtaba
Background: Silicon hydrogel bandage contact lenses are used to enhance epithelial healing, control surface-generated pain, and prevent epithelial erosions after refractive surgery. Considering the importance of faster reepithelialization in preventing complications of photorefractive keratectomy (PRK) and the fact that the features and specifications of these commercially-available lenses are different and their performance as a postoperative bandage lenses would be different also, the aim of this study was comparison the efficacy of senofilcon A and lotrafilcon A after PRK. Methods: In this prospective study, 44 patients with PRK in both eyes randomly received a silicon hydrogel contact lens of senofilcon A in one eye and lotrafilcon A in other eye. Then the epithelial defect size, visual acuity and subjective level of pain and discomfort were measured for both eyes and compared on day 1, 3 and 5 postoperatively. Results: There was no statistical difference in rate of reepithelialization between senofilcon A and lotrafilcon A (P > 0.05). The mean pain and discomfort index was significantly lower in eyes with senofilcon A (P < 0.05). The mean subjective visual scores were similar with both bandage contact lenses (BCLs) (P > 0.05). Conclusion: Silicon hydrogel BCLs are safe and effective for corneal reepithelialization and have great therapeutic outcome on visual outcomes after PRK. But, senofilcon A had better effect on postoperative pain and discomfort which made it superior than lotrafilcon A. However for more conclusive results, it is recommended to study larger sample size with evaluation the possible factors responsible for the obtained findings regarding postoperative pain and discomfort. PMID:23112899
Lee, Seung Mok; Lee, Ji Eun; Lee, Da In; Yu, Hak Sun
This study aimed to evaluate the adhesion of Acanthamoeba trophozoites on cosmetic contact lenses (CLs) with and without CL care multipurpose solution (MPS) treatment. Acanthamoeba lugdunensis L3a trophozoites were inoculated onto disks trimmed from CLs: 1-day Acuvue moist, 1-day Acuvue define, Acuvue 2, and Acuvue 2 define. After 18-hour inoculation, the number of adherent trophozoites was counted under phase contrast microscopy. The effects of MPS, Opti-Free Express, soaking CLs for 6 hours, on Acanthamoeba adhesion were analyzed. Scanning electron microscopic examination was performed for assessment of Acanthamoeba attached on the lens surface. Acanthamoeba trophozoites showed greater adhesion to cosmetic CL (P = 0.017 for 1-day CL and P = 0.009 for 2-week CL) although there was no significant difference between the types of cosmetic CL. On all lenses, the number of adherent Acanthamoeba was significantly reduced after treatment with MPS (P < 0.001 for 1-day Acuvue moist, P = 0.046 for 1-day Acuvue define, P < 0.001 for Acuvue 2, and P = 0.015 for Acuvue 2 define), but there was still significant difference between conventional and cosmetic CLs (P = 0.003 for 1-day CL and P < 0.001 for 2-week CL, respectively). More attachment of Acanthamoeba was observed on colored area and the acanthopodia of Acanthamoeba was placed on the rough surface of colored area. Acanthamoeba showed a greater affinity for cosmetic CL and mostly attached on colored area. Although MPS that contained myristamidopropyl dimethylamine reduced the adhesion rate, there was a significant difference between conventional and cosmetic CLs.
Qu, Xiao-Mei; Dai, Jin-Hui; Jiang, Zhen-Ying; Qian, Yi-Feng
AIM To compare the clinical performance of two types of silicon hydrogel contact lenses used as bandage lenses after LASEK surgery. METHODS A prospective, double-masked study was conducted on 42 eyes of 21 patients who received binocular LASEK surgeries. The interocular difference in spherical equivalent power was less than -1.50D. Patients were randomly assigned to wear Galyfilcon A (Lens A) bandage contact lens in one eye and Balafilcon A (Lens B) in the fellow eye after the surgery. The responses to a subjective questionnaire on comfort of wearing, corneal epithelial status, conjunctival hyperemia, limbal neovascularization, lens fitting and contact lens debris were assessed 1 and 5 days postoperatively. Corneal endothelium was assessed before and 5 days after the surgery upon bandage lens removal. RESULTS There was no difference between the two groups in terms of conjunctival hyperemia, limbal neovascularization, contact lens fitting, corneal epithelial status, corneal endothelium cell density (CD) and endothelium cell size (CS) at any postoperative visit. Complaints of discomfort, including foreign body sensation, pain and intolerance were statistically more among Lens B wearers at any postoperative visit (P<0.05). Lens B appeared to attract much more debris than Lens A at the 5-day post-operative follow-up visit (P<0.01). CONCLUSION The two types of silicon hydrogel lenses investigated in this study demonstrated similar clinical performance in terms of corneal responses and lens fitting. However, Lens A showed a better performance in terms of comfort of wearing and deposit resistance. PMID:22553670
Hsu, Kuan-Hui; Chauhan, Anuj
Extended release of photo-unstable drugs from ophthalmic inserts is not useful unless the loaded drug is protected from degradation. Because of the recent interest in extended drug delivery from contact lenses, it is critical to assess whether photo-unstable drugs can be stabilized by loading in lenses. Here, we focus on dexamethasone, which is prone to degradation and has been explored as a candidate for extended release from contact lenses for periods ranging from 10 hours to several days. Degradation rates of dexamethasone were measured in phosphate-buffered saline and after loading in contact lenses. The degradation rates were measured in a humidified, constant-temperature (32°C) chamber with controlled UV exposure. Contact lenses with various degrees of UV blocking were used to explore the relationship between degradation rates and UV exposure. It is known that vitamin E absorbs UV radiation; thus, it was loaded into the lenses to explore the feasibility of reducing the degradation rates. About 85% of dexamethasone degraded in 20 hours in non-UV blocking lenses, whereas less than 1% degraded in class 1 UV blocking lenses. Incorporation of vitamin E into the non-UV blocking lenses reduced the fractional degradation to 30%. Degradation rates in phosphate-buffered saline were significantly higher than even in non-UV blocking contact lenses. The degradation of dexamethasone can be minimized by using a UV blocking contact lens or incorporating vitamin E into a non-UV blocking lens. Vitamin E incorporation has the dual benefits of improving drug stability and release profiles.
Harris, M G; Chin, R S; Lee, D S; Tam, M H; Dobkin, C E; Dobkins, C E
With increasing scientific evidence demonstrating the harmful effects of ultraviolet (UV) radiation on different ocular tissues, contact lens manufacturers are incorporating UV blocking monomers into their contact lenses. This study evaluated the transmittance spectra of Vistakon's disposable soft contact lenses (1 Day Acuvue, Acuvue, Surevue, and Vistavue). All except Vistavue contain a UV blocking agent. Transmittance for each lens was recorded from 200 to 400 nm on a Shimadzu UV 160U Dual Beam Recording Spectrophotometer. The results indicate that lenses which incorporate the UV blocking monomer significantly reduced the transmission of W radiation while untreated lenses did not. Our findings indicate that 1 Day Acuvue, Surevue, and Acuvue meet the American National Standards Institution (ANSI) Standard Z80.20 for Class 2 UV blockers: a maximum of 30% transmittance of UVA wavelengths and 5% transmittance of UVB wavelengths. In contrast, the Vistavue lens demonstrated negligible UV blockage. Our technique, in which contact lenses were placed directly in front of a measuring beam, was accurate and simpler than previously reported methods and may be useful in future studies. We found that UV blocking soft contact lenses can be a viable alternative for spectacles in protecting internal ocular structures from UV radiation. However, the external structures of the eye remain at risk and would continue to benefit from the use of UV blocking sunglasses or spectacle lenses.
Katsoulos, Konstantinos; Rallatos, Gerasimos Livir; Mavrikakis, Ioannis
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.
Coral-Ghanem, Cleusa; Ghanem, Vinícius Coral; Ghanem, Ramon Coral
Therapeutic contact lenses are useful in a variety of ocular surface diseases. Their main indications are: to relieve the pain; protect ocular surface; promote corneal healing and epithelial regeneration; seal a leaking corneal wound and deliver ophthalmic drugs on the ocular surface. There are several kinds of lens designs and materials, and their choice is dependent on the specific disease to be treated, the duration of treatment and the physiologic needs of the diseased cornea. Bullous keratopathy, recurrent epithelial erosion syndrome, dry eye and postoperative epithelial defects are amongst their indications. Therapeutic contact lenses should not be indicated in the presence of active infectious keratitis or when the patient is not compliant. Corneal neovascularization, giant papillary conjunctivitis and infectious keratitis are serious complications, which can be prevented by correctly fitting and maintaining the therapeutic contact lenses. Silicon-hydrogel therapeutic contact lenses, due to their higher oxygen permeability, allow extended wear schedules, decreasing the need for frequent lens replacement.
Roth, H W; Teuchert, J
In a clinical long-term study over a period of 10 years with 3850 patients wearing hard and soft contact lenses, unusual reactions of the cornea and perilimbal conjunctiva have been observed in 3% of all cases. Mainly corneal abrasions, cracks, clouds and mosaics have been observed, which were analyzed as being rare contact lens complications. The causes were lack of proper maintenance of the contact lenses, such as mistakes in cleaning and disinfecting the lenses, mishandling or toxic and allergic reactions due to cleaning and disinfection solutions. Only exact ophthalmological monitoring of the anterior parts of the eye and laboratory tests on the worn lenses permit differentiation between primary eye diseases and contact lens-induced complications.
Federal Aviation Regulations permit the routine use of contact lenses by civilian pilots to satisfy the distant visual acuity requirements for obtaining medical certificates. Specific information identifying the prevalence of both defective distant v...
Acanthamoeba is a microbe that is very common in tap water. It has two forms: the trophozoite and the cyst. These trophozoites and cysts can stick to the surface of your contact lenses and then infect your eye.
Boost, Maureen; Poon, Kin-Chiu; Cho, Pauline
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.
Hickson-Curran, S B; Nason, R J; Becherer, P D; Davis, R A; Pfeifer, J; Stiegemeier, M J
In response to increasing scientific evidence which indicates that ultraviolet radiation (UVR) is a potential threat to ocular health, Acuvue contact lenses (Vistakon, Johnson & Johnson Vision Products Inc., Jacksonville, Florida) have been developed which incorporate an ultraviolet (UV) blocker within the lens polymer. Data are presented for the first clinical evaluation of Acuvue lenses with UV blocking characteristics. A double-masked, multicenter, prospective clinical trial involving 94 subjects was conducted. The study followed a randomized, parallel group design and consisted of 3 months of daily wear with two-weekly lens replacement. Two thirds of the subjects (61) wore the test lenses (Acuvue with UV blocker) and the remaining subjects (33) wore conventional Acuvue lenses (without UV blocker). Biomicroscopic evaluations indicated that the performance of the test and control lenses was clinically similar. No clinically relevant differences between the test and control lenses were noted in the subjective assessments of vision, comfort, or handling. In addition, no differences were shown for surface deposition, lens durability, visual acuity, and subjective symptoms. The study findings indicate that the addition of a UV blocker to Acuvue contact lenses has been achieved without affecting daily wear clinical performance. Because there is increasing evidence to suggest that the ocular tissues may be damaged by UVR, it is prudent for eye care practitioners to prescribe contact lenses that offer the benefits of both regular replacement and UV protection.
Dreifus, M; Tschopp, H; Bosshard, C
Currently it is believed that correction of anisomyopia with contact lenses is contraindicated because most anisomyopias are axial. By determination of dioptric aniseiconia it has been shown that this is smaller than generally believed also with the correction by contact lenses. In childhood it is advisable to correct an anisomyopia fully as early as possible because the distortion of room perception by spectacles seems to play a much bigger role in higher anisomyopia than the functional aniseiconia. The results are shown in tables.
Plowright, Andrew J; Maldonado-Codina, Carole; Howarth, Gillian F; Kern, Jami; Morgan, Philip B
To compare clinical and subjective quality-of-life (QoL) data for teenagers wearing daily disposable contact lenses or spectacles. This open-label study randomized subjects (aged 13 to 19 years) with no previous contact lens wear experience to nelfilcon A (DAILIES AquaComfort Plus) contact lenses or spectacles for 6 months. A full clinical workup, as well as subjective QoL measures using the Pediatric Refractive Error Profile and Quality of Life Impact of Refractive Correction questionnaires, was conducted at baseline and at week 4 and months 3 and 6, with an additional study visit at week 2 for subjects randomized to wear contact lenses. A total of 110 teenagers were enrolled in the study; 13 discontinued before study completion, 10 (17.5%) from the contact lens group and 3 (5.7%) from the spectacle group (p = 0.04). Visual acuity was good for both groups at all study visits. Biomicroscopy assessments were similar at baseline for both groups. Significant differences in Pediatric Refractive Error Profile responses were noted between vision correction groups across visits for appearance (p < 0.001), satisfaction (p < 0.001), activities (p < 0.001), peer perception (p = 0.003), and overall score (p < 0.001). For Quality of Life Impact of Refractive Correction, the contact lens group gave more favorable responses than the spectacle group (p = 0.02). After 6 months of wearing contact lenses, teenagers had a more positive attitude toward comfort, vision, and safety with contact lenses. No serious adverse events were reported during the study. The daily disposable lenses used in this study are suitable for vision correction for teenagers, offering improvements in QoL measures during the first month of wear, including appearance, satisfaction, activities, and peer perceptions, without negatively impacting vision or eye health. Teenagers were able to handle contact lenses with the same amount of confidence as spectacles.
Malone, James P.; Townsend, R. Reid
Purpose. To determine whether class 1 UV-blocking contact lenses protect against UVB radiation–induced damage in a human lens epithelial cell line (HLE B-3) and postmortem human lenses using a proteomics approach. Methods. HLE B-3 cells were exposed to 6.4 mW/cm2 UVB radiation at 302 nm for 2 minutes (768 mJ/cm2) with or without covering by senofilcon A class 1 UV-blocking contact lenses or lotrafilcon A non–UV-blocking (lotrafilcon A has some UV-blocking ability, albeit minimal) contact lenses. Control cells were not exposed to UVB radiation. Four hours after treatment, cells were analyzed by two-dimensional difference gel electrophoresis and tandem mass spectrometry, and changes in protein abundance were quantified. F-actin and microtubule cytoskeletons were examined by fluorescence staining. In addition, human donor lenses were exposed to UVB radiation at 302 nm for 4 minutes (1536 mJ/cm2). Cortical and epithelial cell proteins were scraped from lens surfaces and subjected to the same protein analyses. Results. Senofilcon A lenses were beneficial for protecting HLE B-3 cells against UVB radiation–induced changes in caldesmon 1 isoform, lamin A/C transcript variant 1, DEAD (Asp-Glu-Ala-Asp) box polypeptide, β-actin, glyceraldehyde 3-phosphate dehydrogenase (G3PDH), annexin A2, triose phosphate isomerase, and ubiquitin B precursor. These contact lenses also prevented actin and microtubule cytoskeleton changes typically induced by UVB radiation. Conversely, non–UV-blocking contact lenses were not protective. UVB-irradiated human lenses showed marked reductions in αA-crystallin, αB-crystallin, aldehyde dehydrogenase 1, βS-crystallin, βB2-crystallin, and G3PDH, and UV-absorbing contact lenses significantly prevented these alterations. Conclusions. Senofilcon A class 1 UV-blocking contact lenses largely prevented UVB-induced changes in protein abundance in lens epithelial cells and in human lenses. PMID:21873653
Attempts to dispel rumors concerning contact lenses and tries to supply prudent-use practices for allowing contact lenses in industry and laboratories. Discusses federal regulations that impact the use of contact lenses in industry, policy statements from medical organizations on use of contact lenses in industrial environments, and the…
Qin, Guoting; Zhu, Zhiling; Li, Siheng; McDermott, Alison M; Cai, Chengzhi
In this work, we developed a simple method to load drugs into commercially available contact lenses utilizing fluorous chemistry. We demonstrated this method using model compounds including fluorous-tagged fluorescein and antibiotic ciprofloxacin. We showed that fluorous interactions facilitated the loading of model molecules into fluorocarbon-containing contact lenses, and that the release profiles exhibited sustained release. Contact lenses loaded with fluorous-tagged ciprofloxacin exhibited antimicrobial activity against Pseudomonas aeruginosa in vitro, while no cytotoxicity towards human corneal epithelial cells was observed. To mimic the tear turnover, we designed a porcine eye infection model under flow conditions. Significantly, the modified lenses also exhibited antimicrobial efficacy against Pseudomonas aeruginosa in the ex vivo infection model. Overall, utilizing fluorous chemistry, we can construct a drug delivery system that exhibits high drug loading capacity, sustained drug release, and robust biological activity. Copyright © 2017 Elsevier Ltd. All rights reserved.
Pek, Y Shona; Wu, Hong; Chow, Edwin Py; Ying, Jackie Y
We aim to develop transparent UV-blocking photochromic soft contact lenses via polymerization of a bicontinuous nanoemulsion. Transparent nanostructured polymers were prepared by incorporating a polymerizable surfactant and thermal initiator together with water, monomers, UV blockers and photochromic dyes. The polymers were characterized using oxygen permeometer, tensile tester, electron microscope, UV spectrophotometer, corneal cell culture and testing in rabbits. The polymers have good oxygen permeability, water content, stiffness, strength and UV-blocking ability comparable to commercial UV-blocking soft contact lenses. Their response to UV light is comparable to photochromic spectacle lenses, particularly in reverse transition from colored to colorless state. They are nontoxic and nonleaching. Our photochromic UV-blocking contact lenses provide a novel alternative to photochromic spectacles.
Keith, David J; Christensen, Mike T; Barry, Jacqueline R; Stein, Jerry M
To determine lysozyme deposition as a function of time in soft, high-water content, ionic (group IV) contact lenses. ACUVUE lenses were worn on an extended-wear basis (15 minutes, 2 hours, 4 hours, 6 hours, 8 hours, 1 day, 2 day, and so forth, up to 11 consecutive days). New lenses were dispensed at the beginning of each lens-wear period. After each wear cycle, lenses were analyzed for lysozyme deposition by high performance liquid chromatography. Lysozyme rapidly accumulated on lenses (15 minutes approximately 55 microg/lens) and reached a plateau level by day 6 ( approximately 1300 microg/lens). Most patients in the study showed a plateau range between 1200 and 1400 microg/lens. Six-month and 12-month follow-up studies with ACUVUE lenses showed minimal variation at the 5-day wear time point between the initial, sixth, and 12th month results. This study measured the rate of lysozyme buildup on lenses over time and demonstrated that lysozyme levels associated with group IV lenses reached a plateau after approximately 1 week of extended wear. Little variability was seen in lens lysozyme deposition up to 1 year later. The information derived from this study concerning the rate and variability of deposition has implications for the design and interpretation of cleaning studies and contact lens performance evaluations.
Peng, Cheng-Chun; Chauhan, Anuj
Cyclosporine A (CyA) is effective in treating chronic dry eyes and contact lens mediated dry eyes. CyA is delivered through eye drops of an oil-in-water emulsion, which has a small residence time in the eyes, leading to low bioavailability. Here we explore delivery of CyA from contact lenses to provide controlled and extended drug delivery with an increased bioavailability due to enhanced ocular residence time. Loading and release profiles of CyA from commercial contact lenses are presented to show that 1-DAY ACUVUE® releases CyA for about a day and extended wear silicone hydrogel (SiH) lenses release CyA for about 2-weeks. The longer duration from SiH lenses compared to the 1-DAY ACUVUE®lens is due to larger partition coefficients in the gel. A novel approach is presented for increasing release duration from the SiH lenses to the desired 1-month through incorporation of Vitamin E. The results show that Vitamin E loaded lenses can provide CyA release within the therapeutic window for a period of about a month. This pilot study demonstrates the promising potential of delivering CyA from contact lens for treatment of chromic dry eyes and contact lens mediated dry eyes. Copyright © 2011 Elsevier B.V. All rights reserved.
Maulvi, Furqan A; Soni, Tejal G; Shah, Dinesh O
Contact lenses for ophthalmic drug delivery have become very popular, due to their unique advantages like extended wear and more than 50% bioavailability. To achieve controlled and sustained drug delivery from contact lenses, researchers are working on various systems like polymeric nanoparticles, microemulsion, micelle, liposomes, use of vitamin E, etc. Numerous scientists are working on different areas of therapeutic contact lenses to treat ocular diseases by implementing techniques like soaking method, molecular imprinting, entrapment of drug-laden colloidal nanoparticles, drug plate/film, ion ligand polymeric systems, supercritical fluid technology, etc. Though sustained drug delivery was achieved using contact lens, the critical properties such as water content, tensile strength (mechanical properties), ion permeability, transparency and oxygen permeability were altered, which limit the commercialization of therapeutic contact lenses. Also issues like drug stability during processing/fabrication (drug integrity test), zero order release kinetics (prevent burst release), drug release during monomer extraction step after fabrication (to remove un-reacted monomers), protein adherence, drug release during storage in packaging solution, shelf life study, cost-benefit analysis, etc. are still to be addressed. This review provides an expert opinion on different methodology to develop therapeutic contact lenses with special remark of their advantages and limitations.
Urgacz, Agnieszka; Mrukwa, Ewa
Allergy is the fifth leading chronic condition in industrialized countries among all ages, and the third most common chronic disease among children under 18 years old. Many of allergic patients also have problems with vision and want to improve their quality of life by wearing contact lenses. They are most frequently young and active individuals, for whom contact lenses provide greater convenience and more satisfying vision correction than spectacles. However, application of high quality and immunologically neutral products do not protect from allergic side reactions. Nowadays, eye-related allergy and contact lens wear concern larger and larger populations worldwide. The purpose of this review is to summarize the studies on ocular complications associated with wearing contact lenses. The article presents indications for allergic patients especially on the care system and wear schedule. PMID:26161062
van der Worp, Eef; Mertz, Cristian
This study aims to evaluate the sagittal height differences among a selection of commercially available monthly or two weekly replacement silicone hydrogel soft lenses. The sagittal height (CL-SAG) of four frequent replacement silicone hydrogel lenses (lotrafilcon B, balafilcon A, comfilcon A and senofilcon A) was measured for all base curve radius manufactured in spherical (-3.00D and +3.00D) and toric (=C-0.75×180°) designs (11 spherical and 8 toric lenses in total). Two different lenses of each lens type were evaluated (the intra CL-SAG) using the SHSOphthalmic omniSpect by Optocraft. The intra CL-SAG difference (the difference between two identical lenses from the same batch) was 11±SD 2μm. The CL-SAG of all minus lenses ranged from 3454 to 3765μm (an inter CL-SAG difference of 311μm), while the plus spherical lenses ranged from 3493 to 3757μm (inter CL-SAG difference 264μm). In the toric lens group, the range in toric minus lenses was 3495-3953μm (inter CL-SAG difference 458μm) and 3493-3980μm in the plus group (inter CL-SAG difference 487μm). The inter CL-SAG difference between the spherical and the toric lenses was statistically significant (p=0.03). Marked differences in sagittal height among different commercially available frequent replacement silicone hydrogel lenses exist. Different lenses with the same package base curve value had marked differences in CL-SAG, with potential clinical significance on-eye in terms of lens behavior. The inter CL-SAG variance in the spherical lens group was smaller than in the toric lens group. Copyright © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Wagner, Sandra; Conrad, Fabian; Bakaraju, Ravi C; Fedtke, Cathleen; Ehrmann, Klaus; Holden, Brien A
The purpose of this study was to investigate the optical zone power profile of the most commonly prescribed soft contact lenses to assess their potential impact on peripheral refractive error and hence myopia progression. The optical power profiles of six single vision and ten multifocal contact lenses of five manufacturers in the powers -1.00 D, -3.00 D, and -6.00 D were measured using the SHSOphthalmic (Optocraft GmbH, Erlangen, Germany). Instrument repeatability was also investigated. Instrument repeatability was dependent on the distance from the optical centre, manifesting unreliable data for the central 1mm of the optic zone. Single vision contact lens measurements of -6.00 D lenses revealed omafilcon A having the most negative spherical aberration, lotrafilcon A having the least. Somofilcon A had the highest minus power and lotrafilcon A the biggest deviation in positive direction, relative to their respective labelled powers. Negative spherical aberration occurred for almost all of the multifocal contact lenses, including the centre-distance designs etafilcon A bifocal and omafilcon A multifocal. Lotrafilcon B and balafilcon A seem to rely predominantly on the spherical aberration component to provide multifocality. Power profiles of single vision soft contact lenses varied greatly, many having a negative spherical aberration profile that would exacerbate myopia. Some lens types and powers are affected by large intra-batch variability or power offsets of more than 0.25 dioptres. Evaluation of power profiles of multifocal lenses was derived that provides helpful information for prescribing lenses for presbyopes and progressing myopes. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Zhang, Jiyan; Wang, Liru; Ma, Zhenya
A focimeter is one of the basic ophthalmic instruments used in every optometric practice, and verification of the accuracy and calibration of the instrument are of the utmost importance. For many years the International Standardization for Organization requires that calibrations for all kinds of focimeters shall be accomplished by using test lenses described in ISO 9342:1996. These test lenses must be of high quality and of nominal back vertex power that is known with high accuracy. With the development of science and technology, ISO 9342 was revised in 2005. A new part ISO 9342-2 had been drafted for test lenses used to calibrate focimeters with contact lens measurement, and the original ISO 9342 was turned into the current ISO 9342-1, which could only be used to calibrate fociemters with spectacle lens measurement. As one of the standard drafters, the background for the newly published ISO 9342-2 is introduced in this study, and comparison between test lenses of ISO 9342-1 and ISO 9342-2 is made. Further, the influence of tolerance and uncertainty in design and production of standard test lenses of ISO 9342-2 is analyzed. The paraxial approximation is used to relate the lens parameters with back vertex power and to calculate the uncertainty budget. Moreover, one set of test lenses conforming to ISO 9342-2 is manufactured and experiments are done with it. Results show that test lenses described in ISO 9342-2 can correct the measurement errors of focimeters used for measuring contact lenses well, especially for spherical aberration, and the correction is more effective for spherical contact lenses with high back vertex power.
Jung, Ji Won; Han, Sun Hyup; Kim, Sang Ah; Kim, Eung Kweon; Seo, Kyoung Yul; Kim, Tae-Im
The purpose of this study was to investigate efficient methods to evaluate the pigment layer location of tinted soft contact lenses and to assess various lens products on the market using those methods. Two types of tinted soft contact lenses with known pigment location embedded or back surface were manufactured and examined. Light microscopy (LM), focused ion beam milling and scanning electron microscopy (FIB-SEM), and Fourier-domain optical coherence tomography (FD-OCT) were used to examine the pigment layer. Lens surface roughness was also measured using atomic force microscopy. In the second part of the experiment, pigment location and surface roughness of a clear lens (Lens A) and eight commercially-available tinted soft contact lenses (Lens B-I) were evaluated using FIB-SEM and FD-OCT. Pigment location could be reliably determined with FIB-SEM and FD-OCT. With LM, 40% of the lens sections were broken or deformed during slide preparation. The pigment particles in Lens B were buried below the front surface and there were no significant differences of roughness between the front and back surfaces. However, all tinted lenses with surface pigment had significant difference of roughness between front and back surfaces at the pigmented area. The FIB-SEM and FD-OCT could reliably locate the pigment layer of tinted soft contact lenses. In addition, lens surface roughness was influenced by pigment layer location. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Compañ, V; Andrio, A; López-Alemany, A; Riande, E; Refojo, M F
Oxygen transport through two extended wear (day and night) hydrogel contact lenses that contain organosilicon moieties (balafilcon A and lotrafilcon A) was studied in the hydrate (hydrogel) and dry (xerogel) states. The water uptake increased the oxygen permeability [(Dk)app] and transmissibility [Dk/L(av)] coefficients of the dry materials by about 70%. The (Dk)app for the hydrated lenses was determined following the so-called stack procedure. The values obtained were 107 +/- 4 barrer for balafilcon A and 141 +/- 5 barrer for lotrafilcon A, about 5-10 times larger than those previously reported for conventional (without organosilicon moieties) extended wear hydrogels contact lenses. The Dk/L(av) for -3.00 diopter lenses (harmonic average thickness, L(av) = 75 +/- 2 microm for lotrafilcon, and 85 +/- 2 microm for balafilcon) was 123 +/- 6 barrer/cm for balafilcon A and 183 +/- 8 barrer/cm for lotralicon A. The minimum oxygen transmissibility 87 barrer/cm stipulated by Holden and Mertz to avoid corneal edema with extended wear contact can be easily achieved with lotrafilcon and balafilcon lenses of diverse dioptric powers if the central and peripheral thickness of the lenses are kept below the critical level of oxygen transmissibility.
Rajagopalan, Aruna S; Bennett, Edward S; Lakshminarayanan, Vasudevan
The purpose of this study is to assess the visual performance of subjects wearing gas-permeable (GP) multifocal contact lenses, soft bifocal contact lenses, GP monovision lenses and spectacles. The study included 32 subjects between the ages of 42 and 65 years wearing GP monovision, the Acuvue Bifocal (Vistakon), the Essentials GP Multifocal (Blanchard), and progressive addition lenses (PAL; spectacles group). There were eight subjects in each of these groups who were already wearing these modalities. Binocular low (18%) and high (95%) contrast acuities were recorded using the Bailey-Lovie chart; binocular contrast sensitivity from 1.5 to 18 cycles per degree (cpd) measured with the Vistech VCTS 6500 system, and monocular glare sensitivity at three luminance settings (400, 100, and 12 foot lamberts) was measured using the brightness acuity tester (BAT). Binocular near visual task performance (a modified version of letter counting method used in previous presbyopic studies) was also assessed. For the contact lens-wearing groups, subjects wearing GP multifocals provided the best binocular high and low contrast acuity followed by soft bifocal wearers. There was relative parity between the binocular high and low contrast acuity with PAL and GP multifocal wearers. Monovision acuity, measured binocularly, was determined to be lower than the other three groups with this difference being most significant with high contrast acuity. Among contact lens-wearing groups, it was observed that GP multifocal lens wearers experienced the lowest amount of monocular disability glare followed by soft bifocal wearers and monovision wearers. Subjects wearing soft bifocal lenses and monovision demonstrated slightly reduced binocular contrast sensitivity at all spatial frequencies. In the contact lens groups, GP multifocal lens wearers had the highest binocular contrast sensitivity at all spatial frequencies, on parity with PAL wearers, except at the highest spatial frequency (18 cpd) at
Morris, Carol A; Maltseva, Inna A; Rogers, Victoria A; Ni, Jing; Khong, Kathleen T; Derringer, Charles B; George, Melanie D; Luk, Andrew S
To assess contact lens preservative uptake and release from multipurpose solutions (MPS) and subsequent acquisition of lens antibacterial activity. Kinetics of uptake and release of poly (hexamethylene biguanide hydrochloride) (PHMB) or polyquaternium-1 (PQ-1) from various contact lenses were studied initially with the pure compounds and then after soaking in MPS containing these compounds. Lenses soaked in MPS were tested for antibacterial activity. Only lenses with a negatively charged component absorbed these preservatives. For lenses containing methacrylic acid (MA), uptake of PHMB from preservative-only solution was fast, yet little was released, in contrast to its rapid release from lenses containing other anionic groups. This trend persisted with PHMB-containing MPS. PQ-1 from preservative-only solution was only absorbed by lenses containing MA and was released from MA-containing hydrogels, but not significantly from an MA-containing silicone hydrogel. Lens uptake of PQ-1 was much lower from MPS and release was essentially undetectable from all lenses evaluated. Antibacterial lens activity was acquired by lenses containing MA after an overnight soak in MPS containing PQ-1, and for balafilcon A and omafilcon A after 5 exchanges in PHMB-containing MPS. Acquired activity was maintained during cycling between artificial tear protein solution and MPS. Lens preservative uptake and its subsequent release are dependent on lens chemistry, preservative nature, and other MPS components. A few lens/solution combinations acquired antibacterial activity after one or more overnight soaks in MPS, depending on the nature of the anionic lens component and the preservative. Uncharged lenses did not acquire antibacterial activity.
Zambelli, Alison M.; Brothers, Kimberly M.; Hunt, Kristin M.; Romanowski, Eric G.; Nau, Amy C.; Dhaliwal, Deepinder K.; Shanks, Robert M. Q.
Objectives To measure the diffusion of topical preparations of moxifloxacin, amphotericin B (AmB), and polyhexamethylene biguanide (PHMB) through silicone hydrogel (SH) contact lenses in vitro. Methods Using an in vitro model, the diffusion of three antimicrobials through SH contact lenses was measured. Diffused compounds were measured using a spectrophotometer at set time points over a period of four hours. The amount of each diffused antimicrobial was determined by comparing the experimental value to a standard curve. A biological assay was performed to validate the contact lens diffusion assay by testing antimicrobial activity of diffused material against lawns of susceptible bacteria (Staphylococcus epidermidis) and yeast (Saccharomyces cerevisiae). Experiments were repeated at least two times with a total of at least 4 independent replicates. Results Our data show detectable moxifloxacin and PHMB diffusion through SH contact lenses at 30 minutes, while amphotericin B diffusion remained below the limit of detection within the 4 hour experimental period. In the biological assay, diffused moxifloxacin demonstrated microbial killing starting at 20 minutes on bacterial lawns, whereas PHMB and amphotericin B failed to demonstrate killing on microbial lawns over the course of the 60 minute experiment. Conclusions In vitro diffusion assays demonstrate limited penetration of certain anti-infective agents through silicone hydrogel contact lenses. Further studies regarding the clinical benefit of using these agents along with bandage contact lens use for corneal pathology are warranted. PMID:25806673
Martin, D K; Holden, B A
The hydrodynamic squeeze pressure in the fluid thin film beneath hydrogel contact lenses fitted onto an axisymmetric model eye were measured. These pressures were due to the contact lens relaxing after deformation by an applied force of similar magnitude to the human eyelid force. The distribution of pressure for contact lenses typically fitted to human eyes was negative with respect to atmospheric pressure at the corneal apex and became less negative at the corneo-scleral limbus. The force that the contact lens applied to the cornea was determined by integrating the pressure distribution from the corneal apex to the limbus. This force varied from 6.0 X 10(-4) N to -7.8 X 10(-1) N depending on the thickness, elastic modulus and bearing relationship of the contact lens. An expression was derived to determine the pressure developed beneath the annulus of the hydrogel contact lens overlapping the cornea, in terms of the measured force over the cornea beneath the contact lens and the chord diameters of the contact lens and cornea. It was found that the deformation of hydrogel contact lenses on the model eye did not follow a linear elastic shell theory.
Sticca, Matheus Porto; Carrijo-Carvalho, Linda C; Silva, Isa M B; Vieira, Luiz A; Souza, Luciene B; Junior, Rubens Belfort; Carvalho, Fábio Ramos S; Freitas, Denise
To report a series of cases of Acanthamoeba keratitis (AK) in scleral lens wearers with keratoconus to determine whether this type of contact lens presents a greater risk for development of infection. This study reports three patients who wore scleral contact lenses to correct keratoconus and developed AK. The diagnoses of AK were established based on cultures of the cornea, scleral contact lenses, and contact lens paraphernalia. This study investigated the risk factors for infections. The possible risks for AK in scleral contact lens wearers are hypoxic changes in the corneal epithelium because of the large diameter and minimal tear exchange, use of large amounts of saline solution necessary for scleral lens fitting, storing the scleral lens overnight in saline solution rather than contact lens multipurpose solutions, not rubbing the contact lens during cleaning, and the space between the cornea and the back surface of the scleral lens that might serve as a fluid reservoir and environment for Acanthamoeba multiplication. Two patients responded well to medical treatment of AK; one is still being treated. The recommendations for use and care of scleral contact lenses should be emphasized, especially regarding use of sterile saline (preferably single use), attention to rubbing the lens during cleaning, cleaning of the plunger, and overnight storage in fresh contact lens multipurpose solutions without topping off the lens solution in the case. Copyright © 2017. Published by Elsevier Ltd.
Singh, Kishan; Nair, Anroop B; Kumar, Ashok; Kumria, Rachna
The success of ocular delivery relies on the potential to enhance the drug bioavailability by controlled and extended release of drug on the eye surface. Several new approaches have been attempted to augment the competence and diminish the intrinsic side effects of existing ocular drug delivery systems. In this contest, progress has been made to develop drug-eluting contact lens using different techniques, which have the potential to control and sustain the delivery of drug. Further, the availability of novel polymers have facilitated and promoted the utility of contact lenses in ocular drug delivery. Several research groups have already explored the feasibility and potential of contact lens using conventional drugs for the treatment of periocular and intraocular diseases. Contact lenses formulated using modern technology exhibits high loading, controlled drug release, apposite thickness, water content, superior mechanical and optical properties as compared to commercial lenses. In general, this review discus various factors and approaches designed and explored for the successful delivery of ophthalmic drugs using contact lenses as drug delivery device PMID:24826007
... 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). ...
Dantas, P E; Nishiwaki-Dantas, M C; Ojeda, V H; Holzchuh, N; Mimica, L J
To evaluate the bacterial contamination of bandage disposable soft contact lenses used in patients following photorefractive keratectomy (PRK) and to correlate our findings with clinical data. Forty-six patients (81 eyes) underwent PRK. Immediately after each procedure, disposable soft contact lenses were positioned with sterile forceps. After 3 days, the lenses were removed in a sterile manner, placed in sterile Eppendorf pipettes containing 8 mL of enriched brain heart infusion broth, and analyzed for microbial contamination. Seven positive cultures were found: six gram positive cocci (7.4%) and one gram negative bacillus (1.2%). There was no clinical correlation with these findings. Isolated microorganisms were similar to those described in the literature as agents of bacterial keratitis and are components of the normal ocular flora. Klebsiela pneumoniae--considered an occasional or transient flora--was the exception. All isolated microorganisms but K. pneumoniae were sensitive to most of the antibiotics tested. Our findings suggest that the risk of infectious keratitis after PRK related to soft contact lens wear for 3 days seems to be low, which may be because lenses were not manipulated by the patient during the wearing period, and the postoperative antibiotic regimen was strictly followed by patients. However, care should be taken to instruct patients in proper lens care practices to reduce the risk of bacterial keratitis in contact lens wear following PRK.
Tavazzi, Silvia; Ferraro, Lorenzo; Cozza, Federica; Pastori, Valentina; Lecchi, Marzia; Farris, Stefano; Borghesi, Alessandro
Drug-loaded contact lenses are emerging as the preferred treatment method for several ocular diseases, and efforts are being directed to promote extended and controlled delivery. One strategy is based on delivery induced by environmental triggers. One of these triggers can be hydrogen peroxide, since many platforms based on drug-loaded nanoparticles were demonstrated to be hydrogen-peroxide responsive. This is particularly interesting when hydrogen peroxide is the result of a specific pathophysiological condition. Otherwise, an alternative route to induce drug delivery is here proposed, namely the mechano-synthesis. The present work represents the proof-of-concept of the mechanosynthesis of hydrogen peroxide in siloxane-hydrogel contact lenses as a consequence of the cleavage of siloxane bonds at the interface between the polymer and water in aqueous phase. Their spongy morphology makes contact lenses promising systems for mechanical-to-chemical energy conversion, since the amount of hydrogen peroxide is expected to scale with the interfacial area between the polymer and water. The eyelid pressure during wear is sufficient to induce the hydrogen peroxide synthesis with concentrations which are biocompatible and suitable to trigger the drug release through hydrogen-peroxide-responsive platforms. For possible delivery on demand, the integration of piezoelectric polymers in the siloxane-hydrogel contact lenses could be designed, whose mechanical deformation could be induced by an applied wireless-controlled voltage.
Selan, Laura; Palma, Stefano; Scoarughi, Gian Luca; Papa, Rosanna; Veeh, Richard; Di Clemente, Daniele; Artini, Marco
To compare silicone-hydrogel, poly(2-hydroxyethyl methacrylate) (pHEMA), and phosphorylcholine-coated (PC-C) contact lenses in terms of their susceptibility to biofilm formation by Staphylococcus epidermidis and Pseudomonas aeruginosa. Laboratory investigation. Biofilm formation on colonized test lenses was evaluated with confocal microscopy and in vitro antibiotic susceptibility assays. The results of the latter assays were compared with those performed on planktonic cultures of the same organism. For both microorganisms, sessile colonies on silicone-hydrogel and pHEMA lenses displayed lower antibiotic susceptibility than their planktonic counterparts. In contrast, the susceptibility of cultures growing on PC-C lenses was comparable with that for planktonic cultures. In particular, minimum inhibitory concentration for Tazocin (piperacillin plus tazobactam; Wyeth Pharmaceuticals, Aprilia, Italy; S. epidermidis) and gentamicin (P. aeruginosa) was identical, either in the presence of PC-C support or in planktonic cultures (Tazocin, = 0.2 mug/ml; gentamicin, 0.4 mug/ml). Minimum inhibitory concentration for imipenem (P. aeruginosa) was two-fold higher for PC-C lenses (0.4 mug/ml) with respect to planktonic cultures (0.2 mug/ml). Confocal microscopy of lenses colonized for 24 hours with P. aeruginosa green fluorescent protein-expressing cells revealed a sessile colonization on silicone-hydrogel lens and a few isolated bacterial cells scattered widely over the surface of the PC-C lens. An increase in antibiotic susceptibility of bacterial cultures was associated with diminished bacterial adhesion. Our results indicate that PC-C lenses seem to be more resistant than silicone-hydrogel and pHEMA lenses to bacterial adhesion and colonization. This feature may facilitate their disinfection.
Mosuela, Reynalyn; Mustafa, Shelan; Gould, Simon; Hassanin, Hany; Alany, Raid G; ElShaer, Amr
There is an immense research interest to utilise contact lens (CLs) as a popular platform for ocular drug delivery. However, CLs are the major predisposing factors of bacterial keratitis which is commonly caused by adhesion of microbes such as Pseudomonas aeruginosa and Staphylococcus epidermidis. The aim of the current study is to explore the effect of surfactants; Poloxamer 188, Polysorbate 80 and Tetronic ® 90R4 (at 0.25% - 3% v/v) on the characteristics of CLs and on the adhesion abilities of Pseudomonas aeruginosa to the lenses' surfaces. CLs were formulated using a hydrophilic monomer; 2-hydroxyethyl methacrylate (HEMA) together with silicone-based polymer such as Poly dimethyl siloxane (PDMS) or 3,3,3-trifluoropropylsilane (FSA) then lenses were polymerized under UV light. The formulated CLs with surfactants were found to have an increased equilibrium water content (EWC) due to hydrophilic moiety present in surfactants. A relationship was deduced between EWC and surface contact angle of lenses containing surfactants; where an increased EWC was associated with a decrease in contact angle reflecting a more hydrophilic surfaces of CLs. Apart from the 3% Polysorbate 80 (p < .0001) CLs, all other formulations had light transmission values over 80%. Lenses with surfactants were found to have lower bacterial ATP concentration than lenses without surfactants. Poloxamer 188 in FSA lenses reduced bacterial adhesion from 4.22 × 10 -4 ± 1.30 × 10 -4 pM to 1.03 × 10 -4 ± 4.86 × 10 -5 pM, a reduction by 75.59% when compared to the control lenses (p = .002). Moreover, 1% Tetronic ® 90R4 in PDMS showed a reduction by 57.17% in ATP concentration. Polysorbate 80 in FSA exhibited the least bacterial adhesion with an average bacterial ATP concentration of 3.85 × 10 -5 ± 2.61 × 10 -5 pM; i.e 90.88% less bacterial ATP than control lenses (p = .001). Bioluminescence studies demonstrated a decrease in Pseudomonas
Mathews, Judith R.; And Others
Four young children were taught contact lens wear using a shaping procedure, which involved praise and tangibles for compliance and time-outs or restraint for noncompliance. At followup, levels of compliance were high for three children, while a subject with Down's syndrome showed low compliance with need for physical restraint throughout.…
Soft toric contact lenses are a good alternative for the optical correction of astigmatism. They provide a wide visual field, quick adaptation process, negligible aniseikonia, together with enhanced comfort and reduced incidence of complications introduced by the lenses for frequent replacement. Still practitioners do not recommend them proactively and the satisfaction obtained by the patients is not high enough. This paper presents two recent studies that investigate the opinions of specialists and contact lens wearers and introduce a new contact lens, with an original design, born after 30 years of domination of only 2 modalities of rotational stabilization: prism ballast and dual thin zones. The lens is manufactured using a silicon-hydrogel material of 2-nd generation that provides sustained comfort and better oxygenation.
Harris, M.G.; Rechberger, J.; Grant, T.; Holden, B.A. )
We evaluated the effectiveness of an in-office microwave disinfection procedure which allowed for the disinfection of up to 40 soft contact lenses at one time. Ciba AOSept cases filled with sterile unpreserved saline were contaminated with one of six FDA test challenge microorganisms at a concentration of approximately 10(3) colony forming units per milliliter (CFU/ml). Twenty cases were placed on the rotating plate of a standard 2450 MHz 650 W microwave oven in a 10-cm diameter circle. The cases were exposed to high intensity microwave irradiation for periods of 0 to 15 min. None of the 6 microorganisms evaluated survived 2 min or longer of microwave exposure. Our findings indicated that microwave irradiation can be a convenient, rapid, and effective method of disinfecting a number of soft contact lenses at one time and thus adaptable as an in-office soft contact lens disinfection procedure.
Weale, R A
During a monitoring study related to photorefractive keratectomy, objective tests with the Oqual (a device that can be attached to the slit-lamp) were made of the image forming quality of treated, central, and untreated peripheral regions of the cornea. In a significant number of cases the untreated part was optically inferior to the treated part. Observations on 183 patients implicated prior contact lens wear: patients who had worn hard or gas permeable lenses scored less well than those wearing soft ones or none at all. The effects of age and length of wear were analysed. With one exception, corneal quality did not correlate with age or with length of contact lens wear either for the total sample (A) or for those aged 40 years and less (B). In A, all contact lens wearers scored less well than those who had never worn any. In B, whose eye lenses were most probably more transparent than those of the older group (A-B), those who had worn hard or gas permeable lenses scored significantly less than soft contact lens wearers or those who had never worn any. Although visual acuity is unimpaired, the optical capacity of the affected peripheral corneal regions appears to be permanently degraded, and the observation may have a potential bearing--for example, on the choice of contact lens types selected for cosmetic reasons. PMID:7696238
Belda-Salmerón, Lurdes; Ferrer-Blasco, Teresa; Albarrán-Diego, César; Madrid-Costa, David; Montés-Micó, Robert
The purpose of this study is to compare the visual performance provided by different daily disposable contact lenses and to analyze its variation over time. Visual performance was evaluated in terms of visual acuity (VA) and contrast sensitivity (CS) in 15 myopic subjects (-0.50 to -4.00 diopters) who had been previously fitted with each one of the following seven types of soft contact lenses: DAILIES TOTAL1 (Alcon, Forth Worth, TX), DAILIES AquaComfort Plus (Alcon), 1-DAY ACUVUE TruEye (Johnson & Johnson Vision Care, Jacksonville, FL), 1-DAY ACUVUE MOIST (Johnson & Johnson Vision Care), SofLens daily disposable (Bausch & Lomb, Rochester, NY), Proclear 1 Day (CooperVision, Fairport, NY), and Clariti 1-Day (Sauflon, Twickenham, United Kingdom). We measured VA at three contrast levels (10%, 50%, and 100%) and CS for three spatial frequencies (10, 20, and 25 cycles/degree). These measurements were performed at 2-hr intervals during a 12-hr period of continuous wearing. Measurements were also performed with ophthalmic lenses before contact lens fitting. Two-way analysis of variance (ANOVA) results revealed significant differences across the lens types and over time for low-contrast VA only. For high- and medium-contrast VA, ophthalmic lens performed better than the contact lenses after 12 hr of use (without statistical differences among the contact lenses). Contrast sensitivity values also showed differences across lenses for the three spatial frequencies under analysis. For each particular lens type, no CS variations were observed with wearing time. Although some of the differences were not statistically significant, we found that, for many of the VA and CS measures, ophthalmic lens and DAILIES TOTAL1 yielded better values than the 1-DAY ACUVUE TruEye and Clariti 1-Day. Assessing VA at different contrasts and CS measurements allowed us to perform a visual function evaluation. Contact lens characteristics such as material and water content, among others, may be the
Plainis, Sotiris; Atchison, David A; Charman, W Neil
Many contact lens (CL) manufacturers produce simultaneous-image lenses in which power varies either smoothly or discontinuously with zonal radius. We present in vitro measurements of some recent CLs and discuss how power profiles might be approximated in terms of nominal distance corrections, near additions, and on-eye visual performance. Fully hydrated soft, simultaneous-image CLs from four manufacturers (Air Optix AQUA, Alcon; PureVision multifocal, Bausch & Lomb; Acuvue OASYS for Presbyopia, Vistakon; Biofinity multifocal- "D" design, Cooper Vision) were measured with a Phase focus Lens Profiler (Phase Focus Ltd., Sheffield, UK) in a wet cell and powers were corrected to powers in air. All lenses had zero labeled power for distance. Sagittal power profiles revealed that the "low" add PureVision and Air Optix lenses exhibit smooth (parabolic) profiles, corresponding to negative spherical aberration. The "mid" and "high" add PureVision and Air Optix lenses have bi-aspheric designs, leading to different rates of power change for the central and peripheral portions. All OASYS lenses display a series of concentric zones, separated by abrupt discontinuities; individual profiles can be constrained between two parabolically decreasing curves, each giving a valid description of the power changes over alternate annular zones. Biofinity lenses have constant power over the central circular region of radius 1.5 mm, followed by an annular zone where the power increases approximately linearly, the gradient increasing with the add power, and finally an outer zone showing a slow, linear increase in power with a gradient being almost independent of the add power. The variation in power across the simultaneous-image lenses produces enhanced depth of focus. The through-focus nature of the image, which influences the "best focus" (distance correction) and the reading addition, will vary with several factors, including lens centration, the wearer's pupil diameter, and ocular
Beyer, Jill; Todani, Amit; Dohlman, Claes
To describe visually debilitating deposit formation on hydrogel contact lenses routinely used for protection in eyes with keratoprosthesis and to present different types of contact lenses that provide improved deposit resistance. Seven keratoprosthesis eyes with a history of rapid and severe deposit formation on their hydrogel lenses were evaluated and documented. The Schirmer values and blink rate of each patient were additionally analyzed. These patients were then subsequently refitted with varying types of contact lenses. When soft hydrogel lenses were replaced with lenses with water-impermeable centers, dramatically fewer deposits accumulated. Deposit formation on hydrogel lenses did not seem to correlate with low Schirmer values but rather with an insufficient blink rate. Excellent deposit resistance can be achieved in these patients with the use of hybrid contact lenses with rigid centers or large-diameter entirely rigid contact lenses.
White, Charles James; DiPasquale, Stephen Anthony; Byrne, Mark Edward
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.
White, Charles J.; DiPasquale, Stephen A.; Byrne, Mark E.
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
Pitt, William G; Jack, Daniel R; Zhao, Yibei; Nelson, Jared L; Pruitt, John D
Characterization of the transport and release of phospholipids from a silicone hydrogel contact lens is required to assess the possible use of these lenses for phospholipid delivery to increase patient comfort. Contact lenses of silicone hydrogel composition were loaded with varying amounts of radiolabeled 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) from a solution of n-propanol. These lenses were eluted at 35°C into artificial tear fluid (ATF) or ATF containing varying amounts of DMPC. The amount of DMPC loaded into a lens is a linear function of the time of exposure to the DMPC/propanol solution. The initial rate of elution into ATF appears to be diffusion controlled for at least 10 h and is proportional to the amount of DMPC loaded. The elution rate decreases as the DMPC concentration in the ATF increases. The ease of loading and the controllable release of DMPC from silicone hydrogels presents the possibility of using such lenses to counter eye discomfort caused by inherently low levels of phospholipid in tears.
Conway, H D
Calculations are made of the effects of base curvature on squeeze pressures in hard contact lenses during blinking. An axisymmetrical model with parabolic profile is used of a cylindrical body (the lens) moving along its axis toward a rigid surface (the eye), from which it is separated by a tear film. The results are compared with those obtained from a two-dimensional model having the same parabolic profile. It is found that the maximum pressures in the axisymmetric case are precisely one-half of those in the corresponding two-dimensional one, irrespective of the base curvature. Thus, estimated pressures using the latter model are likely to be too large. A simple formula is also obtained which shows the effect of base curvature on the force. The calculated pressures (and hence forces) will be further reduced if lens deformation occurs as is the case in soft contact lenses.
of contact lenses . Acta Ophthalmologica. 64:88-92. O’Neal, M., Polse, K., and Sarver, M. 1984. Corneal response to rigid and hydrogel lenses during...Soft Contact Lenses In an Armored Division By William G. Bachman D I John K. Crosley MARECTEI Dudley R. Price Gerard Bentley Patrick Leas Sensory...62777A E162777A87 I BG 168 (U) An Operational Assessment of Extended-Wear Soft Contact Lenses in an Armored Division 12. PERSONALAUTHOR(S) William G
Tavazzi, Silvia; Rossi, Alessandra; Picarazzi, Sara; Ascagni, Miriam; Farris, Stefano; Borghesi, Alessandro
Soft contact lenses used for the correction of ametropia are often made of hydrogel and silicone-hydrogel materials. Since they are placed directly on the surface of the eye and they are hydrated by tears, eye cosmetics can compromise the lens performance and, even worse, can be transported from an external environment to the ocular surface through the contact lens. The diffusion of the dye component of a purple eyeshadow in soft contact lenses of different materials is here evaluated. Diffusivity is found to be typically higher in silicone-hydrogels than in hydrogels. In hydrogels, diffusivity is greater in the case of lower oxygen transmissibility. Despite differences between materials, absorbed mass of dye is much larger (10-100 times) than the expected mass by simple hydration and swelling of the contact lens. The most contaminated materials are also resistant to cleaning solutions. The results indicate that, notwithstanding the complexity of contact lens networks, diffusion of dye is found to follow Fick's law and it is driven by polymer-dye interaction, which governs lens hydration and swelling. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Kim, Eon; Bakaraju, Ravi C; Ehrmann, Klaus
To evaluate the optical power profiles of commercially available soft multifocal contact lenses and compare their optical designs. The power profiles of 38 types of multifocal contact lenses-three lenses each-were measured in powers +6D, +3D, +1D, -1D, -3D, and -6D using NIMO TR1504 (Lambda-X, Belgium). All lenses were measured in phosphate buffered saline across 8 mm optic zone diameter. Refractive index of each lens material was measured using CLR 12-70 (Index Instruments, UK), which was used for converting measured power in the medium to in-air radial power profiles. Three basic types of power profiles were identified: center-near, center-distance, and concentric-zone ring-type designs. For most of the lens types, the relative plus with respect to prescription power was lower than the corresponding spectacle add. For some lens types, the measured power profiles were shifted by up to 1D across the power range relative to their labeled power. Most of the lenses were designed with noticeable amounts of spherical aberration. The sign and magnitude of spherical aberration can either be power dependent or consistent across the power range. Power profiles can vary widely between the different lens types; however, certain similarities were also observed between some of the center-near designs. For the more recently released lens types, there seems to be a trend emerging to reduce the relative plus with respect to prescription power, include negative spherical aberration, and keep the power profiles consistent across the power range.
Tavazzi, Silvia; Ferraro, Lorenzo; Fagnola, Matteo; Cozza, Federica; Farris, Stefano; Bonetti, Simone; Simonutti, Roberto; Borghesi, Alessandro
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.
Horst, Caleb R; Brodland, Benjamin; Jones, Lyndon W; Brodland, G Wayne
The purpose of this study is to demonstrate a novel method for measuring the modulus of contact lenses in their as-received, variable-thickness form and to determine whether modulus varies with location within commercial lenses and whether it is dependent on lens geometry and temperature. The thickness profiles of lenses having powers from -8 diopters (D) to +4 D were measured using a Rehder electronic thickness gauge. Strip-shaped specimens having a width of 5.5 mm were then cut from the lenses. Graphite particles were sprinkled on the specimen surface so that its motions could be tracked using digital image-correlation techniques. The specimens were mounted in a BioTester test system using BioRakes (rather than clamps) and stretched uniaxially until all parts of the lens between the attachment points had elongated by at least 10%. This procedure allowed local modulus values to be determined at 110 locations over the surface of each lens and any property variations within the lenses to be characterized. Tests were performed at 5, 23, and 37°C. Material modulus was found to be essentially constant within any given lens and was independent of the optical power of the lens. Young's Modulus values ranged from 0.3 to 1.9 MPa, depending on the lens manufacturer and product, and some lens materials showed a decrease in modulus with temperature. For the materials tested, those with lower water content had a tendency to exhibit higher moduli. Testing of the kind reported here is important for assessing the efficacy of current and proposed contact lens materials and designs, especially if such designs make use of variable properties to enhance function or fit.
Gong, Celia R; Troilo, David; Richdale, Kathryn
To determine the effect of multifocal contact lenses on accommodation and phoria in children. This was a prospective, non-dispensing, randomized, crossover, single-visit study. Myopic children with normal accommodation and binocularity and no history of myopia control treatment were enrolled and fitted with CooperVision Biofinity single vision (SV) and multifocal (MF, +2.50D center distance add) contact lenses. Accommodative responses (photorefraction) and phorias (modified Thorington) were measured at four distances (>3 m, 100 cm, 40 cm, 25 cm). Secondary measures included high- and low-contrast logMAR acuity, accommodative amplitude, and facility. Differences between contact lens designs were analyzed using repeated measures regression and paired t-tests. A total of 16 subjects, aged 10 to 15 years, completed the study. There was a small decrease in high (SV: -0.08, MF: +0.01) and low illumination (SV: -0.03, MF: +0.08) (both P < .01) visual acuity, and contrast sensitivity (SV: 2.0, MF: 1.9 log units, P = .015) with multifocals. Subjects were more exophoric at 40 cm (SV: -0.41, MF: -2.06 Δ) and 25 cm (SV: -0.83, MF: -4.30 Δ) (both P < .01). With multifocals, subjects had decreased accommodative responses at distance (SV: -0.04; MF: -0.37D, P = .02), 100 cm (SV: +0.37; MF: -0.35D, P < .01), 40 cm (SV: +1.82; MF: +0.62D, P < .01), and 25 cm (SV: +3.38; MF: +1.75D, P < .01). There were no significant differences in accommodative amplitude (P = .66) or facility (P = .54). Children wearing multifocal contact lenses exhibited reduced accommodative responses and more exophoria at increasingly higher accommodative demands than with single vision contact lenses. This suggests that children may be relaxing their accommodation and using the positive addition or increased depth of focus from added spherical aberration of the multifocals. Further studies are needed to evaluate other lens designs, different amounts of positive addition and aberrations, and long
Chateau, N; Baude, D
A model of the presbyopic eye in various viewing conditions is derived as a combination of average clinical data with a monochromatic eye model. The modulation transfer function (MTF), obtained through Fourier optics calculations, is used to define new metrics, which help to predict the visual performance of multifocal contact lenses. The model is applied to the optimization of concentric bifocal contact lenses (BCLs): the optimal center optimal zone diameter (COZD) is determined as a function of the lens addition and decentration, in order to achieve similar average performance in distance and near vision. Calculations predict a decrease of the overall visual performance of optimized bifocal lenses with increasing addition. They also show that a lens shift relative to the pupil has opposite effects on the performance of center near (CN) and center distance (CD) designs. The comparison between these two types of bifocals suggests that better overall performance is obtained when the near correction is supported by the center optical zone. These theoretical predictions are found to be compatible with anterior clinical results obtained with BCLs.
Braus, Barbara Katharina; Riedler, Daniela; Tichy, Alexander; Spergser, Joachim; Schwendenwein, Ilse
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.
Bergmanson, J P; Pitts, D G; Chu, L W
Ultraviolet radiation (UVR) has been demonstrated to be harmful to the cornea, the lens and the retina. Recent research has indicated that, in addition to the epithelial trauma found in UVR-induced keratitis, the deeper corneal layers are also involved. Since trauma to keratocytes and endothelial cells can result in permanent damage or cell loss, it is imperative to protect eyes against excessive dosages of UVR. Standard hydrogel contact lenses (Vistamarc normal) and newly developed UV-filtering hydrogel lenses (Vistakon UV-BLOC) were fitted on five rabbits and compared in protection from harmful UVR (300 nm). The eyes that wore the UV-filtering lens maintained normal corneas; however, the eyes that wore the standard hydrogel lens showed pronounced epithelial, stromal and endothelial changes. We concluded that the UV-filtering lens effectively absorbed the hazardous UV radiation while the standard soft lens provided little protection.
Ciolino, Joseph B; Ross, Amy E; Tulsan, Rehka; Watts, Amy C; Wang, Rong-Fang; Zurakowski, David; Serle, Janet B; Kohane, Daniel S
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
Babaei Omali, Negar; Lada, Mark; Lakkis, Carol; Morgan, Philip B; Nichols, Jason J; Subbaraman, Lakshman N; Jones, Lyndon W
There remains only a small amount of data from human studies demonstrating the effect of contact lens/lens care solution combinations on the deposition of lipids. Therefore, information on the degree to which modern materials deposit lipids when used with contemporary care solutions would be valuable. The present study aims to determine the effect of lens care system combinations on levels of total lipid, cholesterol, and cholesteryl esters extracted from three different contact lenses (CLs) when used with four contemporary care systems. Experienced CL wearers were recruited to participate in this study. Combinations of three CLs (etafilcon A [ETA], galyfilcon A [GALY], and senofilcon A [SENO]) and four CL care solutions (Biotrue, ClearCare, OPTI-FREE PureMoist, and RevitaLens Ocutec) were investigated. A total of 791 CLs were analyzed. Subjects were randomized to one lens type and then used all four lens care solutions in random sequence for 10-14 days before the CLs were collected and analyzed for the amount of cholesterol, cholesteryl esters, and total lipids. The mean range of cholesterol recovered across the different care solutions was 0.34-2.77 μg/lens, 3.48-4.29 μg/lens, and 4.75-6.20 μg/lens for ETA, SENO, and GALY lenses, respectively. Use of OPTI-FREE PureMoist with ETA lenses led to a significantly greater amount of cholesterol being recovered when compared to the use of the other solutions with ETA lenses (P < .05). The mean range of cholesteryl esters recovered across different care solutions was 1.31-2.02 μg/lens, 6.43-7.19 μg/lens, and 7.96-10.13 μg/lens for ETA, SENO, and GALY lenses, respectively. There were no differences in the amount of cholesteryl esters and total lipids extracted for a given lens type when used with any of the four care solutions (P > .05). This study did not demonstrate conclusively that any of the solution/CL combinations were superior to any of the other combinations when the amounts of lipid deposition were compared
Kim, Eon; Bakaraju, Ravi C.; Ehrmann, Klaus
ABSTRACT Purpose To evaluate the optical power profiles of commercially available soft multifocal contact lenses and compare their optical designs. Methods The power profiles of 38 types of multifocal contact lenses—three lenses each—were measured in powers +6D, +3D, +1D, −1D, −3D, and −6D using NIMO TR1504 (Lambda-X, Belgium). All lenses were measured in phosphate buffered saline across 8 mm optic zone diameter. Refractive index of each lens material was measured using CLR 12-70 (Index Instruments, UK), which was used for converting measured power in the medium to in-air radial power profiles. Results Three basic types of power profiles were identified: center-near, center-distance, and concentric-zone ring-type designs. For most of the lens types, the relative plus with respect to prescription power was lower than the corresponding spectacle add. For some lens types, the measured power profiles were shifted by up to 1D across the power range relative to their labeled power. Most of the lenses were designed with noticeable amounts of spherical aberration. The sign and magnitude of spherical aberration can either be power dependent or consistent across the power range. Conclusions Power profiles can vary widely between the different lens types; however, certain similarities were also observed between some of the center-near designs. For the more recently released lens types, there seems to be a trend emerging to reduce the relative plus with respect to prescription power, include negative spherical aberration, and keep the power profiles consistent across the power range. PMID:27748699
Lindskoog Pettersson, Anna; Wahlberg Ramsay, Marika; Lundström, Linda; Rosén, Robert; Nilsson, Maria; Unsbo, Peter; Brautaset, Rune
The aim of the present project was to investigate accommodative behavior in young adults and adolescents fitted with an aspheric multifocal (center distance) contact lens with focus on evaluating whether these lenses can be an alternative treatment for subjects in which a reduced level of blur and thereby accommodation in near vision is aimed at. Twenty normal subjects aged between 21 and 35 years participated in the study. Aberrometry was perfomed using a Zywave™ aberrometer, first on the uncorrected eyes of all subjects, and again while the subjects wore a multifocal contact lens with a +1.00 add. A Shin-Nippon N Vision-K 5001 Autoref-Keratometer was used to measure accommodative response with two different refractive corrections: (1) habitual spectacle correction only, and (2) habitual correction and a aspheric multifocal (center distance) contact lens. Four hours of adaptation to the lens was allowed. The lag when wearing only the habitual spectacles was compared with the lag while wearing both the habitual spectacles and the aspheric multifocal contact lens. The mean lag of accommodation for the subject group was 0.85 D (±0.57 SD) and 0.75 D (±0.52 SD) without and with the multifocal lens, respectively. Statistical analyses showed no difference in lag (t = 0.8479, p = 0.407) with and without the lens. In conclusion, young normal subjects do not relax accommodation when fitted with aspheric multifocal center distance lenses when the addition is +1.00. It is therefore unlikely that subjects with accommodative ability, in whom the treatment purpose is to reduce blur and thereby accommodation, can be effectively treated with such lenses.
Walker, Jon; Young, Graeme; Hunt, Chris; Henderson, Terri
To evaluate the clinical performance of two daily disposable contact lenses: 1-DAY ACUVUE (1DA) (etafilcon A, Johnson & Johnson Vision Care) and FOCUS DAILIES with AquaComfort (FD) (nelfilcon A, CIBA Vision, Inc.), which contains a quickly released moisture enhancing agent, polyvinyl alcohol (PVA). This was a 1-week, daily wear, subject-masked, bilateral, parallel group study with subjects randomly assigned to one of two daily disposable soft contact lenses. Subjects were existing soft contact lens wearers in the age range 18-39 years with a spherical refraction between -0.50 and -6.00 D. Subjects were assessed at baseline and after 1 week. Assessments included both subjective (symptoms, wearing time, vision) and objective (lens fit and ocular health) outcomes. Twenty clinical sites enrolled 282 subjects (74% female) of whom 276 (98%) successfully completed the study. Significantly more 1DA wearers reported higher mean comfort scores than with FD (3.95 versus 3.41, respectively, P<0.0001). End-of-day comfort means were also significantly higher with the 1DA group compared to the FD group (3.3 versus 3.0, P=0.03). The 1DA group reported significantly longer mean overall wearing time (1DA was worn on average 0.66+/-0.30 h longer than FD, P=0.03) and longer mean comfortable wearing time (1DA was worn on average 1.73+/-0.35 h longer than FD, P<0.0001). The 1DA lens generally showed significantly better on-eye fitting in terms of movement in primary (P<0.0001) and upgaze (P<0.0001) and ease of removal from the eye (92% versus 63%, P<0.0001) compared to FD. There was significantly less corneal staining observed with the 1DA wearing eyes compared with the FD wearing eyes (23% versus 45%, respectively, P<0.0001). Finally, there was a weak correlation between corneal staining and comfort for FD (r=0.27, P=0.002, n=136), but not for 1DA (r=-0.11, P=0.18, n=140). Subjective and objective clinical performance differences between two commonly used daily disposable lenses
Monsálvez-Romín, Daniel; Domínguez-Vicent, Alberto; García-Lázaro, Santiago; Esteve-Taboada, José J; Cerviño, Alejandro
The power profile of multifocal contact lenses has been demonstrated to report important information that could be used during the fitting process. The aim of this work is to describe the power profile of a recent set of gas permeable multifocal contact lenses as a function of the pupil radius. The measured multifocal contact lenses have a centre-distance design, and are available with five distance-vision diameters (XS, S, M, L and XL) and two different additions: Type A (up to +2.00 D) and Type B (up to +2.50 D). The optical device NIMO TR1504 (Lambda-X, Nivelles, Belgium) was used to obtain the power profile measurements. The optical lens power distribution as a function of the aperture radius was described in terms of radial computed colour maps, radial averaged power profiles, addition, and lens portion used for near vision. The amount of total addition achieved depends on the diameter of the distance-vision area. That is, the bigger the distance vision area, the bigger the radius of the lens in order to get the same level of addition. In other words, the XS lens provides higher addition values compared to the XL lens design for a given aperture. The XS and S designs seem to be aimed to favour near vision, whereas the L and XL designs seem to favour distance vision. For this reason, patients who demand good distance vision might benefit from the L or XL designs, and those with high demand on near-vision tasks might benefit from the XS or S designs. The M design could be the best option for those patients who have the same needs for distance and near vision. © 2017 Optometry Australia.
Jung, Ji Won; Han, Sun Hyup; Park, Si Yoon; Kim, Eung Kweon; Seo, Kyoung Yul; Kim, Tae-Im
To evaluate the effects of the location of pigments in decorative tinted soft contact lenses on the ocular surface. Thirty test subjects were enrolled in this study. All subjects wore the following types of contact lenses, classified according to the location of the pigment layer, in one eye in three different testing sessions: conventional clear lenses, tinted lenses with a pigment layer embedded in the lens matrix, and tinted lenses with an exposed pigment layer on the surface. Tear samples were collected, the ocular surface status was evaluated, and subjective symptoms were surveyed after lens wear for 8 hours. The tinted lenses with surface pigments resulted in a greater increase in epidermal growth factor and interleukin-8 levels compared with the clear lenses and tinted lenses with embedded pigments (p < 0.050). Ocular surface parameters and subjective symptom scores were significantly different among three lens types (p < 0.050), with the clear lenses showing superior results compared with the two tinted lenses (p < 0.050). The tinted lenses with exposed pigments resulted in a greater degree of conjunctival redness and ocular surface staining and poorer symptom scores compared with the tinted lens with embedded pigments (p < 0.050). Our results suggest that the presence of surface pigments in tinted contact lenses increases ocular inflammation and results in a poorer ocular surface status and greater discomfort compared with clear lenses and tinted lenses with an embedded pigment layer.
Read, Michael L; Morgan, Philip B; Maldonado-Codina, Carole
This work sought to undertake a comprehensive investigation of the measurement errors associated with contact angle assessment of curved hydrogel contact lens surfaces. The contact angle coefficient of repeatability (COR) associated with three measurement conditions (image analysis COR, intralens COR, and interlens COR) was determined by measuring the contact angles (using both sessile drop and captive bubble methods) for three silicone hydrogel lenses (senofilcon A, balafilcon A, lotrafilcon A) and one conventional hydrogel lens (etafilcon A). Image analysis COR values were about 2 degrees , whereas intralens COR values (95% confidence intervals) ranged from 4.0 degrees (3.3 degrees , 4.7 degrees ) (lotrafilcon A, captive bubble) to 10.2 degrees (8.4 degrees , 12.1 degrees ) (senofilcon A, sessile drop). Interlens COR values ranged from 4.5 degrees (3.7 degrees , 5.2 degrees ) (lotrafilcon A, captive bubble) to 16.5 degrees (13.6 degrees , 19.4 degrees ) (senofilcon A, sessile drop). Measurement error associated with image analysis was shown to be small as an absolute measure, although proportionally more significant for lenses with low contact angle. Sessile drop contact angles were typically less repeatable than captive bubble contact angles. For sessile drop measures, repeatability was poorer with the silicone hydrogel lenses when compared with the conventional hydrogel lens; this phenomenon was not observed for the captive bubble method, suggesting that methodological factors related to the sessile drop technique (such as surface dehydration and blotting) may play a role in the increased variability of contact angle measurements observed with silicone hydrogel contact lenses.
Aller, Thomas A; Liu, Maria; Wildsoet, Christine F
Most studies have reported only minimal reductions in myopia progression with bifocal or progressive multifocal spectacles, although somewhat larger, although mostly still clinically insignificant, effects have been reported in children with nearpoint esophoria and/or accommodative dysfunctions. The CONTROL study was a 1-year, prospective, randomized, clinical trial of bifocal contact lenses for control of myopia in children with eso fixation disparities at near. Eighty-six myopic subjects, aged 8 to 18 years, were enrolled in the study after passing the screening examination. Of these, 79 completed lens assignment and 78 completed the study. The mean refractive error of these 79 subjects was -2.69 ± 1.40D (SD), and all had progressed by -0.50D or more since their last examination. All subjects also had eso fixation disparity at near. Subjects were randomly assigned to wear either Vistakon Acuvue 2 (single-vision soft contact lenses [SVSCLs]) or Vistakon Acuvue Bifocal (bifocal soft contact lenses [BFSCLs]). Bifocal adds were selected to neutralize the associated phoria. Treatment outcomes included cycloplegic autorefraction and axial length, assessed in terms of changes after 6 and 12 months of treatment from pretreatment baseline values. The BFSCLs significantly slowed myopia progression, with statistically significant differences between the treatment groups after 6 months. After 12 months of treatment, the SVSCL group had progressed by -0.79 ± 0.43D compared with -0.22 ± 0.34D for the BFSCL group (cycloplegic objective spherical equivalent, average of two eyes). Corresponding axial length changes were 0.24 ± 0.17 mm and 0.05 ± 0.14 mm, respectively. All of these differences were found to be statistically significant (unpaired t-tests, p < 0.001). The distance center bifocal contact lenses tested in this study achieved greater control over myopia progression and axial elongation (>70%) compared with most published results with multifocal spectacles. Further
Xie, Zhuoying; Li, Linliang; Liu, Panmiao; Zheng, Fuyin; Guo, Liuyang; Zhao, Yuanjin; Jin, Lu; Li, Tingting; Gu, Zhongze
A circlular structural-colored contact lens is reported, which is fabricated by replicating self-assembled colloidal photonic crystal templates. The structural-colored contact lenses not only display variable and brilliant color under light illumination, but also avoid the addition of any colorants to the hydrogel lenses and prevent the potential harm posed by traditional colored contact lenses. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Karlgard, C C S; Jones, L W; Moresoli, C
Hydrogel contact lenses can be used as bandage lenses to protect the corneal surface after injury. The use of novel silicon-based hydrogel lens materials as bandage lenses has not gained widespread acceptance. As a first step toward advocating their usefulness as bandage lenses, their interaction with ocular pharmaceuticals must be understood because topical agents are often administered in conjunction with bandage lenses. The in vitro uptake and release of ciprofloxacin from silicone-based hydrogel (SH) and conventional pHEMA-based (CH) hydrogel contact lenses was examined by spectrophotometric evaluation of the drug concentration in saline solution. The hydrogel contact lenses tested showed similar drug uptake (average 1800 microg/lens) but different levels of drug release. Multiphoton laser microscopy indicated that ciprofloxacin was distributed throughout the lens thickness, with higher levels of drug at the surface owing to drug precipitation. The drug adsorption onto the lenses was partially reversible. The SH lenses released a lower amount of drug than CH lenses (72 vs. 168 microg/lens). Ionic lenses released less drug than non-ionic lenses (127 vs. 151 microg/lens). The differences in ciprofloxacin uptake and release between SH and CH materials may not be clinically significant because the amount of drug released from all lenses would be above the MIC(90) of ciprofloxacin for common ocular pathogens. These results indicate that material properties have a significant impact on drug-lens interactions.
Park, William L; Sunness, Janet S
To describe the use of red contact lenses to alleviate photophobia in patients with cone disorders. Retrospective interventional case series. Twenty-three patients with achromatopsia or an acquired cone disorder with complaints of severe photophobia were fit with absorptive red soft contact lenses to alleviate photophobia and improve their ability to use their remaining vision more effectively The contact lenses immediately resolved the aversion to light, with dramatic improvement in visual function in all patients (determined by observation of the patient and by patient report). It allowed eight patients to become eligible to drive. Red contact lenses successfully alleviate photophobia in patients with cone disorders.
Bullimore, Mark A.
ABSTRACT Purpose There is increasing interest in fitting children with soft contact lenses. This review collates data from a range of studies to estimate the incidence of complications, specifically corneal infiltrative events and microbial keratitis, in patients under the age of 18 years. Methods Peer-review papers were identified using PubMed and the Web of Science. A broad range of studies are summarized including large-scale epidemiological studies of contact lens–related complications, hospital-based case series, long- and short-term prospective studies, and multicenter retrospective studies. Results Nine prospective studies representing 1800 patient years of wear in 7- to 19-year-olds include safety outcomes. In three large prospective studies representing between 159 and 723 patient years of soft contact lens wear in patients 8 to 14 years, the incidence of corneal infiltrative events is up to 136 per 10,000 years. Data from a large retrospective study show similar rates of corneal infiltrative events: 97 per 10,000 years in 8- to 12-year-olds (based on 411 patient years of wear) and 335 per 10,000 years in 13- to 17-year-olds (based on 1372 patient years of wear). None of the prospective studies report any cases of microbial keratitis. Five clinical studies where safety data are not reported constitute a further 493 patient years. One retrospective study found no cases of microbial keratitis occurred in 8- to 12-year-olds (411 patient years) and an incidence of 15 per 10,000 patient years in 13- to 17-year-olds (1372 patient years)—no higher than the incidence of microbial keratitis in adults wearing soft contact lenses on an overnight basis. Conclusions The overall picture is that the incidence of corneal infiltrative events in children is no higher than in adults, and in the youngest age range of 8 to 11 years, it may be markedly lower. PMID:28514244
Thakur, Deeksha V; Gaikwad, Ujjwala N
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. 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. 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). 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.
until they are worn again. The proper selection of changes in the intact rabbit cornea’s metabolism and these agents is an area that requires... nurse or ophthalmic technician to optical aid. assist in the CL clinic, whose special role will be to instruct subjects in the handling and care of their...Acanthamoeba castellani and behaviour of spherical and aspherical contact lenses Acanthamoeba polyphaga. Ophthalmology. 17: 286-290. exposed to +Gz
Jinabhai, Amit; O'Donnell, Clare; Tromans, Cindy; Radhakrishnan, Hema
This study investigated how aberration-controlling, customised soft contact lenses corrected higher-order ocular aberrations and visual performance in keratoconic patients compared to other forms of refractive correction (spectacles and rigid gas-permeable lenses). Twenty-two patients (16 rigid gas-permeable contact lens wearers and six spectacle wearers) were fitted with standard toric soft lenses and customised lenses (designed to correct 3rd-order coma aberrations). In the rigid gas-permeable lens-wearing patients, ocular aberrations were measured without lenses, with the patient's habitual lenses and with the study lenses (Hartmann-Shack aberrometry). In the spectacle-wearing patients, ocular aberrations were measured both with and without the study lenses. LogMAR visual acuity (high-contrast and low-contrast) was evaluated with the patient wearing their habitual correction (of either spectacles or rigid gas-permeable contact lenses) and with the study lenses. In the contact lens wearers, the habitual rigid gas-permeable lenses and customised lenses provided significant reductions in 3rd-order coma root-mean-square (RMS) error, 3rd-order RMS and higher-order RMS error (p ≤ 0.004). In the spectacle wearers, the standard toric lenses and customised lenses significantly reduced 3rd-order RMS and higher-order RMS errors (p ≤ 0.005). The spectacle wearers showed no significant differences in visual performance measured between their habitual spectacles and the study lenses. However, in the contact lens wearers, the habitual rigid gas-permeable lenses and standard toric lenses provided significantly better high-contrast acuities compared to the customised lenses (p ≤ 0.006). The customised lenses provided substantial reductions in ocular aberrations in these keratoconic patients; however, the poor visual performances achieved with these lenses are most likely to be due to small, on-eye lens decentrations. © 2014 The Authors Ophthalmic & Physiological
Lee, Se Eun; Kim, So Ra; Park, Mijung
AIM To determine the effect of pH, osmolality, and buffering system on the oxygen permeability (Dk) of soft contact lenses. METHODS Two hydrogel lenses (nelfilcon A and etafilcon A) and 2 silicone hydrogel lenses (lotrafilcon A and balafilcon A) were used in the study. These lenses were incubated in phosphate-buffered saline (PBS) and borate-buffered saline (BBS) solutions adjusted by 0.8 pH increments to a pH in the range of 5.8-9.0 or in hypotonic (280 mOsmol/kg), isotonic (310 mOsmol/kg) and hypertonic (380 mOsmol/kg) PBS solutions. Polarographic method was used for measuring the Dk and lenses were stacked as 4 layers to correct the boundary effect. RESULTS Dk values of all contact lenses measured in BBS solutions were more stable than those in PBS solutions. Especially the etafilcon A lens showed a relative big change compared with other types of contact lenses at the same conditions. When the osmolality of PBS solution increased from hypotonic to hypertonic, Dk of all contact lenses decreased. Variations in Dk existed depending on lens materials, etafilcon A lens was the most affected and nelfilcon A was the least affected by osmolality. CONCLUSION From the result obtained, it is revealed that Dk of contact lenses is changed by the pH, osmolality, and buffering condition of tear. Thus, Dk of contact lens can be varied by the lens wearers' physiological and/or pathological conditions. PMID:26558223
González-Chomón, Clara; Silva, Maite; Concheiro, Angel; Alvarez-Lorenzo, Carmen
Combination of the ability of contact lenses (CLs) to act as a physical barrier against airborne antigen and to serve as a sustained depot of antihistaminic drugs may improve the efficiency of treatments of some ocular allergic diseases. The aim of this work was to develop CLs that exhibit affinity to olopatadine by mimicking the composition of the natural H1-receptor for which olopatadine behaves as a selective antagonist. Functional monomers that match the chemical groups of the receptor and application of the molecular imprinting technology led to hydrogels able to load high amounts of olopatadine and to sustain the release once in contact with lachrymal fluid. Optimized hydrogels prepared with acrylic acid, 2-acrylamido-2-methyl-1-propanesulfonic acid and benzylmethacrylate as functional monomers provided in few hours olopatadine concentrations similar to those of commercially available eye drops but the levels could be sustained for a whole day, demonstrating their efficacy. Olopatadine-loaded CLs successfully passed the HET-CAM test of ocular irritancy and showed good compatibility with mast cells. They were able to inhibit the release of histamine and TNF-α from sensitized mast cells, proving their potential application in preventing and treating allergic conjunctivitis. Contact lenses (CLs) with affinity for antiallergic drugs may constitute an advantageous alternative to eye drops in management of ocular allergies for both contact lens wearers and patients who eventually use neutral CLs as therapeutic platforms. The present work represents a step forward in the state of the art of drug-CL combo products by (i) mimicking the composition of the human receptor of the drug, (ii) exploring combinations of functional monomers that include a monomer (2-acrylamido-2-methyl-1-propanesulfonic acid; AMPSA) with a strong acid group (pKa<4) able to enhance the interaction of the network with olopatadine in the saline environment of the lachrymal fluid, and (iii
Marx, Sebastian; Lauenborg, Bo; Kern, Jami R
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.
Dutta, Debarun; Vijay, Ajay K; Kumar, Naresh; Willcox, Mark D P
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.
Lopes-Ferreira, Daniela P; Neves, Helena I F; Faria-Ribeiro, Miguel; Queirós, António; Fernandes, Paulo R B; González-Méijome, José M
To evaluate the impact of eye and head rotation in the measurement of peripheral refraction with an open-field autorefractometer in myopic eyes wearing two different center-distance designs of multifocal contact lenses (MFCLs). Nineteen right eyes from 19 myopic patients (average central M ± SD = -2.67 ± 1.66 D) aged 20-27 years (mean ± SD = 23.2 ± 3.3 years) were evaluated using a Grand-Seiko autorefractometer. Patients were fitted with one multifocal aspheric center-distance contact lens (Biofinity Multifocal D(®)) and with one multi-concentric MFCL (Acuvue Oasys for Presbyopia). Axial and peripheral refraction were evaluated by eye rotation and by head rotation under naked eye condition and with each MFCL fitted randomly and in independent sessions. For the naked eye, refractive pattern (M, J0 and J45) across the central 60° of the horizontal visual field values did not show significant changes measured by rotating the eye or rotating the head (p > 0.05). Similar results were obtained wearing the Biofinity D, for both testing methods, no obtaining significant differences to M, J0 and J45 values (p > 0.05). For Acuvue Oasys for presbyopia, also no differences were found when comparing measurements obtained by eye and head rotation (p > 0.05). Multivariate analysis did not showed a significant interaction between testing method and lens type neither with measuring locations (MANOVA, p > 0.05). There were significant differences in M and J0 values between naked eyes and each MFCL. Measurements of peripheral refraction by rotating the eye or rotating the head in myopic patients wearing dominant design or multi-concentric multifocal silicone hydrogel contact lens are comparable. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Skipper, Richard S.; Spencer, Ian D.
The rapid and impressive growth of China has been achieved on the back of highly labour intensive industries, often in manufacturing, and at the cost of companies and jobs in Europe and America. Approaches that worked well in the 1990's to reduce production costs in the developed countries are no longer effective when confronted with the low labour costs of China and India. We have looked at contact lenses as a product that has become highly available to consumers here but as an industry that has reduced costs by moving to low labour cost countries. The question to be answered was, "Do we have the skill to still make the product in the UK, and can we make it cheap enough to export to China?" if we do not, then contact lens manufacture will move to China sooner or later. The challenge to enter the markets of the BRIC (Brazil, Russia, India and China) countries is extremely exciting as here is the new money, high growth and here is a product that sells to those with disposable incomes. To succeed we knew we had to be radical in our approach; the radical step was very simple: to devise a process in which each step added value to the customer and not cost to the product. The presentation examines the processes used by the major producers and how, by applying good manufacturing practice sound scientific principles to them, the opportunity to design a new low cost patented process was identified.
Xiao, Xinxin; Siepenkoetter, Till; Conghaile, Peter Ó; Leech, Dónal; Magner, Edmond
A lactate/O 2 enzymatic biofuel cell (EBFC) was prepared as a potential power source for wearable microelectronic devices. Mechanically stable and flexible nanoporous gold (NPG) electrodes were prepared using an electrochemical dealloying method consisting of a pre-anodization process and a subsequent electrochemical cleaning step. Bioanodes were prepared by the electrodeposition of an Os polymer and Pediococcus sp. lactate oxidase onto the NPG electrode. The electrocatalytic response to lactate could be tuned by adjusting the deposition time. Bilirubin oxidase from Myrothecium verrucaria was covalently attached to a diazonium-modified NPG surface. A flexible EBFC was prepared by placing the electrodes between two commercially available contact lenses to avoid direct contact with the eye. When tested in air-equilibrated artificial tear solutions (3 mM lactate), a maximum power density of 1.7 ± 0.1 μW cm -2 and an open-circuit voltage of 380 ± 28 mV were obtained, values slightly lower than those obtained in phosphate buffer solution (2.4 ± 0.2 μW cm -2 and 455 ± 21 mV, respectively). The decrease was mainly attributed to interference from ascorbate. After 5.5 h of operation, the EBFC retained 20% of the initial power output.
Batalu, Nicolae Dan; Semenescu, Augustin; Mates, Ileana Mariana; Negoita, Olivia Doina; Purcarea, Victor Lorin; Badica, Petre
Contact lenses are an attractive alternative for vision corrections. Their improvement can be achieved by optimizing the geometry, use of new materials, and application of high precision processing technologies. The optimized design can be obtained by computer-aided design, considering the principles of geometrical optics. Inventor Professional and other similar advanced 3D CAD software allows complex approaches, selection of suitable materials with better mechanical/ optical properties. This is useful for the preparation of the virtual design for 3D printing or CNC fabrication. A finite element analysis is also of interest for testing the best design/ material choice. In this paper, the finite element analysis for a tri-curve contact lens was applied. The selected materials were PMMA and polycarbonate. The applied compressive loads were in the range from 10 to 100MPa. Our results showed that the best scenario was for the polycarbonate, but PMMA also had a high safety factor. The maximum compression load with a reasonable safety factor (of 7-9 depending on materials) was 12MPa. PMID:29450337
Land, Adrian D; Penno, Katie L; Brzezinski, Jennifer L
All contact lenses (corrective/noncorrective) are considered Class II or Class III medical devices under the Federal Food, Drug, and Cosmetic Act, which also states that contact lenses can only be obtained with a prescription. The Forensic Chemistry Center of the US Food & Drug Administration has examined over 300 decorative, noncorrective contact lenses obtained without a prescription. Our observations indicate that 60% of the counterfeit lenses and 27% of the unapproved lenses examined were positive for microbial contamination. Twenty-nine different brands of noncorrective contact lenses were examined, and 48% of them had at least one sample positive for microbial contamination. Each microorganism was further identified using DNA sequencing. Contaminated contact lenses are associated with numerous health risks, including ocular infections and conjunctivitis leading to permanent visual impairment or blindness. These results support the contention that acquiring contact lenses without a prescription is a considerable threat to consumer health and safety. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.
Green, J Angelo; Phillips, K Scott; Hitchins, Victoria M; Lucas, Anne D; Shoff, Megan E; Hutter, Joseph C; Rorer, Eva M; Eydelman, Malvina B
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.
Amin, R M; Dean, M T; Zaumetzer, L E; Poiesz, B J
The virucidal efficacy of various commercially available contact lens care cleaning regimens on human immunodeficiency virus (HIV-1) contaminated contact lenses using either cursory or meticulous cleaning with a rubber policeman was evaluated. Levels of infectious HIV-1 remaining on individual contact lenses were determined by cultivating the lenses with target HUT-78 cells and subsequently analyzing the cultures for the production of HIV-1 p24 by antigen capture and for HIV-1 gag gene DNA content by the polymerase chain reaction. The data indicate that most of the lens care regimens tested, when coupled with meticulous rubbing, were capable of safely decontaminating the contact lenses, that is, they reduce the amount of infectious HIV-1 on the lenses by greater than a 10 log concentration (10(-10], relative to standard controls. Most tested lens care regimens, if properly followed, would virtually eliminate any chance of the lens serving as a vector for HIV.
Hsu, Kuan-Hui; de la Jara, Percy Lazon; Ariyavidana, Amali; Watling, Jason; Holden, Brien; Garrett, Qian; Chauhan, Anuj
To develop a contact lens system that will control the release of an osmoprotectant and a moisturizing agent with the aim to reduce symptoms of ocular dryness. Profiles of the release of osmoprotectant betaine and moisturizing agent dexpanthenol from senofilcon A and narafilcon B contact lenses were determined in vitro under sink conditions. Both types of lenses were also infused with vitamin E to increase the duration of drug release due to the formation of the vitamin E diffusion barriers in the lenses. The release profiles from vitamin E-infused lenses were compared with those from the control lenses. Both dexpanthenol and betaine are released from commercial silicone hydrogel lenses for only about 10 min. Vitamin E loadings into contact lenses at about 20-23% can increase the release times to about 10 h, which is about 60 times larger compared to the control unmodified lenses. Vitamin E-loaded silicone hydrogel contact lenses released betaine and dexpanthenol in a controlled fashion.
Maulvi, Furqan A; Soni, Tejal G; Shah, Dinesh O
Current dry eye treatment includes delivering comfort enhancing agents to the eye via eye drops, but low residence time of eye drops leads to low bioavailability. Frequent administration leads to incompliance in patients, so there is a great need for medical device such as contact lenses to treat dry eye. Studies in the past have demonstrated the efficacy of hyaluronic acid (HA) in the treatment of dry eyes using eye drops. In this paper, we present two methods to load HA in hydrogel contact lenses, soaking method and direct entrapment. The contact lenses were characterized by studying their optical and physical properties to determine their suitability as extended wear contact lenses. HA-laden hydrogel contact lenses prepared by soaking method showed release up to 48 h with acceptable physical and optical properties. Hydrogel contact lenses prepared by direct entrapment method showed significant sustained release in comparison to soaking method. HA entrapped in hydrogels resulted in reduction in % transmittance, sodium ion permeability and surface contact angle, while increase in % swelling. The impact on each of these properties was proportional to HA loading. The batch with 200-μg HA loading showed all acceptable values (parameters) for contact lens use. Results of cytotoxicity study indicated the safety of hydrogel contact lenses. In vivo pharmacokinetics studies in rabbit tear fluid showed dramatic increase in HA mean residence time and area under the curve with lenses in comparison to eye drop treatment. The study demonstrates the promising potential of delivering HA through contact lenses for the treatment of dry eye syndrome.
Hart, D E; Shih, K L
The microbial flora and fauna of 25 high water content nonionic "soft" contact lenses worn by patients on an extended wear basis, 4 hand-cleaned patient-worn lenses, and 4 improperly maintained lenses were compared. Almost all the patient-worn lenses (24 of 25) were free of viable microorganisms, whereas all the hand-cleaned lenses (4 of 4) were contaminated with different microorganisms. This study showed that hand contact is a major source of microbial contamination of a lens and that usually the hand-transported microorganisms do not survive permanently on the lens in a healthy, normal eye. Improperly maintained lenses demonstrated pathogenic microbial associations. Proof of the eye's potent antimicrobial environment was demonstrated. Thus, microorganism-lens associations are largely due to lens handling and inappropriate maintenance regimens. Typically there are few microorganisms on an extended wear soft lens while it is being worn.
Filipecka, Katarzyna; Budaj, Mariusz; Miskowiak, Bogdan; Makowska-Janusik, Małgorzata; Filipecki, Jacek
The polymeric materials: hydrogel, silicone--hydrogel and methacrylic acid are used in ophthalmology for the manufacture of contact lenses. It is important to research the structure of these materials, mainly the prevalence of free volumes. The study has been conducted in order to comparison the presence of free volume gaps in the structure of the polymer soft contact lenses: Etafilcon A (hydrogel), Narafilcon A (silicone-hydrogel) and the polymer rigid gas permeable (RGP) contact lens (Fluor-Silicon-Methacrylat-Copolymer). In addition, to demonstrate differences in the occurrence of free volumes between types of represented contact lenses. Three types of polymer contact lenses were used as materials: Etafilcon A, Narafilcon A and Fluor-Silicon-Methacrylat-Copolymer. The study was done by means of positron annihilation lifetime spectroscopy (PALS). As a result of the performed measurements, a graphical curve resulted which describes the relationship between the number of the annihilation acts in the time function. Significant changes were observed in the ortho-positronium long life component τ3 and their intensities between the examined polymer contact lenses. The conducted study using the Tao-Eldrup model indicates the presence of free volume holes in all research materials. There is a clear difference in the free volume sizes and their fractions between measured contact lenses are connected with oxygen permeability in these lenses. The results lead to the following connection: contact lenses of higher oxygen permeability coefficients and a water content of less, have more and larger free volumes than contact lenses of less oxygen permeability coefficient.
Zambelli, Alison M; Brothers, Kimberly M; Hunt, Kristin M; Romanowski, Eric G; Nau, Amy C; Dhaliwal, Deepinder K; Shanks, Robert M Q
To measure the diffusion of topical preparations of moxifloxacin, amphotericin B (AmB), and polyhexamethylene biguanide (PHMB) through silicone hydrogel (SH) contact lenses (CLs) in vitro. Using an in vitro model, the diffusion of three antimicrobials through SH CLs was measured. Diffused compounds were measured using a spectrophotometer at set time points over a period of 4 hr. The amount of each diffused antimicrobial was determined by comparing the experimental value with a standard curve. A biological assay was performed to validate the CL diffusion assay by testing antimicrobial activity of diffused material against lawns of susceptible bacteria (Staphylococcus epidermidis) and yeast (Saccharomyces cerevisiae). Experiments were repeated at least two times with a total of at least four independent replicates. Our data show detectable moxifloxacin and PHMB diffusion through SH CLs at 30 min, whereas AmB diffusion remained below the limit of detection within the 4-hr experimental period. In the biological assay, diffused moxifloxacin demonstrated microbial killing starting at 20 min on bacterial lawns, whereas PHMB and AmB failed to demonstrate killing on microbial lawns over the course of the 60-min experiment. In vitro diffusion assays demonstrate limited penetration of certain anti-infective agents through SH CLs. Further studies regarding the clinical benefit of using these agents along with bandage CL for corneal pathologic condition are warranted.
Falk, Magnus; Andoralov, Viktor; Blum, Zoltan; Sotres, Javier; Suyatin, Dmitry B; Ruzgas, Tautgirdas; Arnebrant, Thomas; Shleev, Sergey
Here we present unequivocal experimental proof that microscale cofactor- and membrane-less, direct electron transfer based enzymatic fuel cells do produce significant amounts of electrical energy in human lachrymal liquid (tears). 100 μm diameter gold wires, covered with 17 nm gold nanoparticles, were used to fashion three-dimensional nanostructured microelectrodes, which were biomodified with Corynascus thermophilus cellobiose dehydrogenase and Myrothecium verrucaria bilirubin oxidase as anodic and cathodic bioelements, respectively. The following characteristics of miniature glucose/oxygen biodevices operating in human tears were registered: 0.57 V open-circuit voltage, about 1 μW cm(-2) maximum power density at a cell voltage of 0.5 V, and more than 20 h operational half-life. Theoretical calculations regarding the maximum recoverable electrical energy can be extracted from the biofuel and the biooxidant, glucose and molecular oxygen, each readily available in human lachrymal liquid, fully support our belief that biofuel cells can be used as electrical power sources for so called smart contact lenses. Copyright © 2012 Elsevier B.V. All rights reserved.
Masters, Jordan; Kocak, Mehmet; Waite, Aaron
To compare the risk for microbial keratitis in contact lens wearers stratified by wear schedule with the risk after laser in situ keratomileusis (LASIK). Hamilton Eye Institute and Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, USA. Comparative metaanalysis and literature review. An extensive literature search was performed in the PubMed database between December 2014 and July 2015. This was followed by a metaanalysis using a mixed-effects modeling approach. After 1 year of daily soft contact lens wear, there were fewer microbial keratitis cases than after LASIK, or approximately 2 cases fewer cases per 10 000 (P = .0609). If LASIK were assumed to have essentially a 1-time risk for microbial keratitis, 5 years of extrapolation would yield 11 more cases per 10 000 with daily soft contact lens wear than with LASIK, or approximately 3 times as many cases (P < .0001). The extended use of soft contact lenses led to 12 more cases at 1 year than LASIK, or approximately 3 times as many cases (P < .0001), and 81 more cases at 5 years (P < .0001). When incorporating an estimated 10% retreatment rate for LASIK, these results changed very little. Microbial keratitis is a relatively rare complication associated with contact lens use and LASIK postoperatively. The risk for microbial keratitis was similar between patients using contact lenses for 1 year compared with LASIK. Over time, the risk for microbial keratitis was higher for contact lens use than for LASIK, specifically with extended-wear lenses. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.
Sulley, Anna; Hawke, Ryan; Lorenz, Kathrine Osborn; Toubouti, Youssef; Olivares, Giovanna
Rotational stability of toric soft contact lenses (TSCLs) is achieved using a range of designs. Designs utilising prism or peripheral ballast may result in residual prism in the optic zone. This study quantifies the vertical prism in the central 6mm present in TSCLs with various stabilisation methods. Vertical prism was computed using published refractive index and vertical thickness changes in the central optic zone on a full lens thickness map. Thickness maps were measured using scanning transmission microscopy. Designs tested were reusable, silicone hydrogel and hydrogel TSCLs: SofLens(®) Toric, PureVision(®)2 for Astigmatism, PureVision(®) Toric, Biofinity(®) Toric, Avaira(®) Toric, clariti(®) toric, AIR OPTIX(®) for ASTIGMATISM and ACUVUE OASYS(®) for ASTIGMATISM; with eight parameter combinations for each lens (-6.00DS to +3.00DS, -1.25DC, 90° and 180° axes). All TSCL designs evaluated had vertical prism in the optic zone except one which had virtually none (0.01Δ). Mean prism ranged from 0.52Δ to 1.15Δ, with three designs having prism that varied with sphere power. Vertical prism in ACUVUE OASYS(®) for ASTIGMATISM was significantly lower than all other TSCLs tested. TSCL designs utilising prism-ballast and peri-ballast for stabilisation have vertical prism in the central optic zone. In monocular astigmats fitted with a TSCL or those wearing a mix of toric designs, vertical prism imbalance could create or exacerbate disturbances in binocular vision function. Practitioners should be aware of this potential effect when selecting which TSCL designs to prescribe, particularly for monocular astigmats with pre-existing binocular vision anomalies, and when managing complaints of asthenopia in monocular astigmats. Copyright © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Hu, Xiaohong; Tan, Huaping; Chen, Pin; Wang, Xin; Pang, Juan
Hydrogel contact lens is an attractive drug carrier for the delivery of ophthalmic drugs. But limited drug loading capacity and burst release restricted its application in this field. Polymer micelle laden hydrogel contact lenses were designed for ophthalmic drug delivery in the work. β-CD/PAA/PEG ternary system was chosen to form polymer micelle. The micelle size could be adjusted by β-CD content and PAA/PEG concentration. The zeta potential of micelle was irrelevant to β-CD content, but influenced by PAA/PEG concentration. The absorbed drug concentration in micelle solution depended on both β-CD content and PAA/PEG concentration. Polymer micelle laden hydrogels were obtained by radical polymerization in situ. The transparency of polymer micelle laden hydrogel declined with PAA/PEG concentration increasing. The equilibrium water content and water loss showed that polymer micelle laden hydrogel with higher PAA/PEG concentration was in a higher swollen state. The dynamic viscoelastic properties howed that all polymer micelle laden hydrogels had some characteristics of crosslinked elastomers. The surface structure of freeze dried composite hydrogels was different from freeze dried pure hydrogel. The drug loading and releasing behaviors were detected to evaluate the drug loading and releasing capacity of hydrogels using orfloxacin and puerarin as model drugs. The results indicated the polymer micelle in hydrogel could hold or help to hold some ophthalmic drugs, and slow down orfloxacin release speed or keep puerarin stably stay for a time in hydrogels. In the end, it was found that the transparency of composite hydrogel became better after the hydrogel had been immersed in PBS for several weeks.
Lee, Dasom; Cho, Seungkwon; Park, Hwa Sung; Kwon, Inchan
Ocular drug delivery through hydrogel contact lenses has great potential for the treatment of ocular diseases. Previous studies showed that the loading of lipophilic vitamin E to silicone-hydrogel contact lenses was beneficial in ocular drug delivery. We hypothesized that vitamin E loading to another type of popular hydrogel contact lenses, pHEMA-hydrogel contact lenses, improves ocular drug delivery by increasing the drug loading or the duration of drug release. Loading of vitamin E to pHEMA-hydrogel contact lenses significantly increased the loading of a hydrophilic drug surrogate (Alexa Fluor 488 dye) and two hydrophilic glaucoma drugs (timolol and brimonidine) to the lenses by 37.5%, 19.1%, and 18.7%, respectively. However, the release duration time was not significantly altered. Next, we hypothesized that the lipophilic nature of vitamin E attributes to the enhanced drug loading. Therefore, we investigated the effects of co-loading of another lipophilic vitamin, vitamin A, on drug surrogate delivery. We found out that vitamin A loading also increased the loading of the drug surrogate to pHEMA-hydrogel contact lenses by 30.3%. Similar to vitamin E loading, vitamin A loading did not significantly alter the release duration time of the drug or drug surrogate.
Lee, Dasom; Cho, Seungkwon; Park, Hwa Sung; Kwon, Inchan
Ocular drug delivery through hydrogel contact lenses has great potential for the treatment of ocular diseases. Previous studies showed that the loading of lipophilic vitamin E to silicone-hydrogel contact lenses was beneficial in ocular drug delivery. We hypothesized that vitamin E loading to another type of popular hydrogel contact lenses, pHEMA-hydrogel contact lenses, improves ocular drug delivery by increasing the drug loading or the duration of drug release. Loading of vitamin E to pHEMA-hydrogel contact lenses significantly increased the loading of a hydrophilic drug surrogate (Alexa Fluor 488 dye) and two hydrophilic glaucoma drugs (timolol and brimonidine) to the lenses by 37.5%, 19.1%, and 18.7%, respectively. However, the release duration time was not significantly altered. Next, we hypothesized that the lipophilic nature of vitamin E attributes to the enhanced drug loading. Therefore, we investigated the effects of co-loading of another lipophilic vitamin, vitamin A, on drug surrogate delivery. We found out that vitamin A loading also increased the loading of the drug surrogate to pHEMA-hydrogel contact lenses by 30.3%. Similar to vitamin E loading, vitamin A loading did not significantly alter the release duration time of the drug or drug surrogate. PMID:27678247
Dursch, T J; Liu, D E; Oh, Y; Radke, C J
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
Mrazovac, Danijela; Barisić Kutija, Marija; Vidas, Sania; Kuzman, Tomislav; Petricek, Igor; Jandroković, Sonja; Kalauz, Miro; Cerovski, Branimir
Keratoconus is a progressive, non-inflammatory corneal ectasia characterized by thinning and weakening of the corneal stroma which results in its' protrusion. The onset is during puberty and progresses until the fourth decade of life. In earlier stages, good visual acuity can be provided with spectacles. With progression, contact lenses are considered to be a better therapy. Aim of this study was to determine if there is statistically significant difference between best corrected visual acuity (BCVA) obtained by spectacles and contact lenses in newly diagnosed keratoconus patients, as well as to determine which type of contact lenses provide better BCVA in keratoconus patients. We conducted a 5-year retrospective study of all 2891 patients attending our Contact Lens Department for the first time, searching for patients newly diagnosed with keratoconus. Data were obtained on gender, age, education level, treated eyes, corneal changes, keratoconus severity, BCVA with spectacles, contact lenses and best fitted contact lens type. All patients underwent standard ophthalmic exam, refractometry and keratometry have been done, followed by a spectacles correction and lens fitting. Wilcoxon signed rank test was used for statistical analysis. Results showed that of all 2891 patients examined for the first time, 137 patients (4.74%) have been newly diagnosed with heratoconus, there was male bias (72.26%), mean age 27.7 +/- 9.9 years. Most patients had high school education (51.11%), 3.70% had present corneal changes, 50.37% had mild heratoconus. Majority had keratoconus on both eyes (36.3%) or keratoconus of right eye (26.67%). There was a statistically significant difference (p<0.001) between the BCVA obtained with contact lenses (0.82 +/- 0.21 Snellen chart) rather than spectacles (0.37 +/- 0.27 Snellen chart). The best corrected visual acuity was achieved with rigid gas permeable (RGP) lenses in majority of kera- toconus eyes (51.85%), with semi-gas permeable (SGP) lenses
Brothers, Kimberly M.; Nau, Amy C.; Romanowski, Eric G.; Shanks, Robert M. Q.
Purpose This study was designed to measure the impact of bacterial biofilms on diffusion of an ocular therapeutic through silicone hydrogel bandage lenses in vitro. Methods An assay was designed to study the passage of a commonly used steroid dexamethasone through the silicone hydrogel soft contact lenses. Diffused dexamethasone was measured using a spectrophotometer over a period of 18 hours and quantified using a standard curve. This assay was performed with control and Staphylococcus epidermidis biofilm-coated contact lenses composed of lotrafilcon A and methafilcon. Biofilms were formed in brain heart infusion broth supplemented with D-glucose. Results The presented data validate a simple in vitro model that can be used to measure penetration of a topical therapeutic through silicone hydrogel soft contact lenses. Using this model we measured a reduction of dexamethasone diffusion by up to 88% through S. epidermidis biofilm-coated silicon hydrogel lenses compared to control lenses. Conclusions The results of this in vitro study demonstrate that bacterial biofilms impede dexamethasone diffusion through silicon hydrogel contact lenses, and warrant future studies regarding the clinical benefit of using ocular therapeutics in the setting of bandage contact lens use for corneal epithelial defects. PMID:25090165
Brothers, Kimberly M; Nau, Amy C; Romanowski, Eric G; Shanks, Robert M Q
This study was designed to measure the impact of bacterial biofilms on diffusion of an ocular therapeutic through silicone hydrogel bandage lenses in vitro. An assay was designed to study the passage of a commonly used steroid, dexamethasone, through silicone hydrogel soft contact lenses. Diffused dexamethasone was measured using a spectrophotometer over a period of 18 hours and quantified using a standard curve. This assay was performed with control and Staphylococcus epidermidis biofilm-coated contact lenses comprised of lotrafilcon A and methafilcon. Biofilms were formed in brain heart infusion broth supplemented with D-glucose. The presented data validate a simple in vitro model that can be used to measure the penetration of a topical therapeutic through silicone hydrogel soft contact lenses. Using this model, we measured a reduction in dexamethasone diffusion up to 88% through S. epidermidis biofilm-coated silicone hydrogel lenses compared with control lenses. The results of this in vitro study demonstrate that bacterial biofilms impede dexamethasone diffusion through silicone hydrogel contact lenses and warrant future studies regarding the clinical benefit of using ocular therapeutics in the setting of bandage contact lens use for corneal epithelial defects.
Fagnola, Matteo; Pagani, Marco Paolo; Maffioletti, Silvio; Tavazzi, Silvia; Papagni, Antonio
Two experimental spectroscopic methods for the determination of the content of hyaluronic acid in solution are provided based on the formation of complexes between the hyaluronic acid and cationic dyes with sensitivity down to concentrations of either 0.25 or 2.5 microg/ml. These techniques were applied to commercial hydrophilic contact lenses and allowed (i) distinguishing among contact lenses either loaded or non-loaded with hyaluronic acid, (ii) determining, for the loaded ones, the content of hyaluronic acid, (iii) evaluating the release of hyaluronic acid by the lens in solution, and (iv) determining the role of the hyaluronic acid in preventing the adsorption and the successive release by the contact lens of other components which can be present, for example, in the conservation solutions and/or in the blisters of the lenses. The results represent new physical chemistry insights for the field of contact lenses with impact on the advancement of current technology.
Kang, Pauline; Fan, Yvonne; Oh, Kelly; Trac, Kevin; Zhang, Frank; Swarbrick, Helen
To investigate changes in peripheral refraction with under-, full, and over-correction of central refraction with commercially available single vision soft contact lenses (SCLs) in young myopic adults. Thirty-four myopic adult subjects were fitted with Proclear Sphere SCLs to under-correct (+0.75 DS), fully correct, and over-correct (-0.75 DS) their manifest central refractive error. Central and peripheral refraction were measured with no lens wear and subsequently with different levels of SCL central refractive error correction. The uncorrected refractive error was myopic at all locations along the horizontal meridian. Peripheral refraction was relatively hyperopic compared to center at 30 and 35° in the temporal visual field (VF) in low myopes and at 30 and 35° in the temporal VF and 10, 30, and 35° in the nasal VF in moderate myopes. All levels of SCL correction caused a hyperopic shift in refraction at all locations in the horizontal VF. The smallest hyperopic shift was demonstrated with under-correction followed by full correction and then by over-correction of central refractive error. An increase in relative peripheral hyperopia was measured with full correction SCLs compared with no correction in both low and moderate myopes. However, no difference in relative peripheral refraction profiles were found between under-, full, and over-correction. Under-, full, and over-correction of central refractive error with single vision SCLs caused a hyperopic shift in both central and peripheral refraction at all positions in the horizontal meridian. All levels of SCL correction caused the peripheral retina, which initially experienced absolute myopic defocus at baseline with no correction, to experience absolute hyperopic defocus. This peripheral hyperopia may be a possible cause of myopia progression reported with different types and levels of myopia correction.
Kang, Pauline; Fan, Yvonne; Oh, Kelly; Trac, Kevin; Zhang, Frank; Swarbrick, Helen A
To compare changes in peripheral refraction with single-vision (SV) and multifocal (MF) correction of distance central refraction with commercially available SV and MF soft contact lenses (SCLs) in young myopic adults. Thirty-four myopic adult subjects were fitted with Proclear Sphere and Proclear Multifocal SCLs to correct their manifest central refractive error. Central and peripheral refraction were measured with no lens wear and subsequently with the two different types of SCL correction. At baseline, refraction was myopic at all locations along the horizontal meridian. Peripheral refraction was relatively hyperopic compared with center at 30 and 35 degrees in the temporal visual field (VF) in low myopes, and at 30 and 35 degrees in the temporal VF, and 10, 30, and 35 degrees in the nasal VF in moderate myopes. Single-vision and MF distance correction with Proclear Sphere and Proclear Multifocal SCLs, respectively, caused a hyperopic shift in refraction at all locations in the horizontal VF. Compared with SV correction, MF SCL correction caused a significant relative myopic shift at all locations in the nasal VF in both low and moderate myopes and also at 35 degrees in the temporal VF in moderate myopes. Correction of central refractive error with SV and MF SCLs caused a hyperopic shift in both central and peripheral refraction at all positions in the horizontal meridian. Single-vision SCL correction caused the peripheral retina, which initially experienced absolute myopic defocus at baseline with no correction to experience an absolute hyperopic defocus. Multifocal SCL correction resulted in a relative myopic shift in peripheral refraction compared with SV SCL correction. This myopic shift may explain recent reports of reduced myopia progression rates with MF SCL correction.
Rahmani, Saeed; Mohammadi Nia, Mohadeseh; Akbarzadeh Baghban, Alireza; Nazari, Mohammad Reza; Ghassemi-Broumand, Mohammad
Three major parts of sunlight consist of visible, ultraviolet and infrared radiation. Exposure to ultraviolet radiation (UVR) can result in a spectrum of skin and ocular diseases. UV-blocking contact lenses help provide protection against harmful UV radiation. We studied the ultraviolet and visible light rays transmission in some soft UV-blocking contact lenses. Four available tinted soft lenses (Acuvue Moist, Zeiss CONTACT Day 30 Air spheric, Pretty Eyes and Sauflon 56 UV) have been evaluated for UV and visible transmission. One-way ANOVA testing was performed to establish is there a statistically significant difference between the UV regions and visible spectra means for the contact lenses (α=0.05). Pretty Eyes, Zeiss CONTACT, Acuvue Moist and Sauflon 56 UV showed UV-B transmittance value of 0.65%, 10.69%, 1.22%, and 5.78%, respectively. Pretty Eyes and Acuvue Moist had UV-A transmittance values of 32% and 34%, Sauflon 56 UV and Zeiss CONTACT had transmittance values of 48% and 43%, respectively. All of the studied lenses transmitted at least 94.6% on the visible spectrum. The results of the one-way ANOVA statistical analysis show that a statistically significant difference exists within the group of contact lenses tested for the visible (p<0.001), UV-B (p<0.001) and UV-A (p<0.001) portions of the spectrum (α=0.05). Acuvue Moist has the best UV-blocking property and also visible transmission between other tested contact lenses in this study. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Severinsky, Boris; Yahalom, Claudia; Florescu Sebok, Tatiana; Tzur, Veronika; Dotan, Shlomo; Moulton, Eric Alan
Supplemental digital content is available in the text. To determine the benefits provided by centrally red-tinted contact lenses on visual acuity, contrast sensitivity (CS), photophobia, and quality of life in patients with degenerative retinal diseases.We evaluated the impact of centrally red-tinted hydrogel contact lenses on nine patients (aged 15 to 22 years) with severe photophobia and poor visual acuity. Each patient underwent a full eye examination with and without contact lenses, including visual acuity at distance and near, CS, eye movement recording for nystagmus, refraction, and a fundus examination. All patients completed a low vision-adapted VFQ 25-Version 2000 quality-of-life questionnaire.Seven of nine patients demonstrated improvement in binocular visual acuity as well as improvement in CS with the tinted contact lenses. Subjectively, all patients described a major improvement in their photophobia both outdoors and indoors, as well as a marked improvement in quality of life.Red-tinted contact lenses may dramatically improve visual functions, outdoor performance, and quality of life of patients suffering from retinal diseases. These lenses should be a part of the regular assessment in specialty clinics treating patients with low vision, glare, and photophobia.
Gavara, Rafael; Compañ, Vicente
Oxygen permeability, diffusion coefficient of the sodium ions and water flux and permeability in different conventional hydrogel (Hy) and silicone-hydrogel (Si-Hy) contact lenses have been measured experimentally. The results showed that oxygen permeability and transmissibility requirements of the lens have been addressed through the use of siloxane containing hydrogels. In general, oxygen and sodium chloride permeability values increased with the water content of the lens but there was a percolation phenomenon from a given value of water uptake mainly in the Si-Hy lenses which appeared to be related with the differences between free water and bound water contents. The increase of ion permeability with water content did not follow a unique trend indicating a possible dependence of the chemical structure of the polymer and character ionic and non-ionic of the lens. Indeed, the salt permeability values for silicone hydrogel contact lenses were one order of magnitude below those of conventional hydrogel contact lenses, which can be explained by a diffusion of sodium ions occurring only through the hydrophilic channels. The increase of the ionic permeability in Si-Hy materials may be due to the confinement of ions in nanoscale water channels involving possible decreased degrees of freedom for diffusion of both water and ions. In general, ionic lenses presented values of ionic permeability and diffusivity higher than most non-ionic lenses. The tortuosity of the ionic lenses is lower than the non-ionic Si-Hy lenses. Frequency 55 and PureVision exhibited the highest water permeability and flux values and, these parameters were greater for ionic Si-Hy lenses than for ionic conventional hydrogel lenses. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2218-2231, 2017. © 2016 Wiley Periodicals, Inc.
Lee, Se Eun; Kim, So Ra; Park, Mijung
Purpose. To investigate the effect of tear protein deposition on the change in oxygen permeability (Dk) of soft contact lenses (SCL). Methods. Three hydrogel lenses (polymacon, nelfilcon A, and etafilcon A) and two silicon hydrogel lenses (lotrafilcon A and balafilcon A) were investigated. Etafilcon A lenses were incubated in artificial tear solution for 1, 6, 12, and 48 h, whereas the other SCL were incubated for 1, 3, 7, and 14 days. Oxygen permeability was measured using the polarographic method, and lenses were stacked in four layers to correct the boundary effect. Results. The Dk of all investigated SCL was decreased by the protein deposition. Silicone hydrogel lenses showed a smaller deposition of artificial tear proteins than conventional hydrogel lenses. However, their Dk was reduced twofold than those of 3 conventional hydrogel lenses when compared at the same level of protein deposition. Despite a large amount of total deposited protein in etafilcon A lenses, their Dk was more stable than other SCL. Conclusions. From the results, it was revealed that the Dk of SCL is different from the value provided by manufacturers because of the tear protein deposition on surface and/or in pore of SCL; however, the degree of Dk change in SCL was not simply correlated with the amount of tear protein deposition. Thus, it is considered that the correlation between tear protein deposition and properties of lens materials affects Dk change.
Purpose. To investigate the effect of tear protein deposition on the change in oxygen permeability (Dk) of soft contact lenses (SCL). Methods. Three hydrogel lenses (polymacon, nelfilcon A, and etafilcon A) and two silicon hydrogel lenses (lotrafilcon A and balafilcon A) were investigated. Etafilcon A lenses were incubated in artificial tear solution for 1, 6, 12, and 48 h, whereas the other SCL were incubated for 1, 3, 7, and 14 days. Oxygen permeability was measured using the polarographic method, and lenses were stacked in four layers to correct the boundary effect. Results. The Dk of all investigated SCL was decreased by the protein deposition. Silicone hydrogel lenses showed a smaller deposition of artificial tear proteins than conventional hydrogel lenses. However, their Dk was reduced twofold than those of 3 conventional hydrogel lenses when compared at the same level of protein deposition. Despite a large amount of total deposited protein in etafilcon A lenses, their Dk was more stable than other SCL. Conclusions. From the results, it was revealed that the Dk of SCL is different from the value provided by manufacturers because of the tear protein deposition on surface and/or in pore of SCL; however, the degree of Dk change in SCL was not simply correlated with the amount of tear protein deposition. Thus, it is considered that the correlation between tear protein deposition and properties of lens materials affects Dk change. PMID:28280635
Del Águila-Carrasco, Antonio J; Domínguez-Vicent, Alberto; Pérez-Vives, Cari; Ferrer-Blasco, Teresa; Montés-Micó, Robert
To assess the effect of different disposable soft contact lenses upon corneal thickness, and upon anterior and posterior corneal curvatures using a dual-Scheimpflug imaging based device. Twenty-eight young, healthy subjects wore four different types of daily disposable soft contact lenses on four different days: Dailies Total1, Proclear 1 Day, Clariti 1-Day and 1-Day Acuvue Moist. The lenses had different material and water content. Pachymetry maps and keratometry values were obtained using the Galilei G4 twice a day: one before putting the lens on and one after an eight-hour period of contact-lens wear. Measurements were also recorded without any contact lenses being worn during a day. Clariti 1-Day lens caused the greatest thickening in the central (8.9±2.8 μm; p<0.01) and in the peripheral cornea (10.1±4.6 μm; p<0.01), whereas Dailies Total1 was the lens that had the most similar behaviour to the non-contact lens scenario. All the lenses caused a slight flattening in the anterior corneal curvature, except Clariti 1-Day, which induced a very slight steepening. The four lenses caused a steepening of different magnitude in the posterior corneal curvature. The magnitude of the changes introduced by the use of soft contact lenses over the eight-hour wearing period was rather small. Thus it is probable it will not influence the vision nor the comfort of the subject. Also, variations on corneal parameters seem to depend on the type of contact lens used. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Omali, Negar Babaei; Subbaraman, Lakshman N.; Coles-Brennan, Chantal; Fadli, Zohra; Jones, Lyndon W.
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
Omali, Negar Babaei; Subbaraman, Lakshman N; Coles-Brennan, Chantal; Fadli, Zohra; Jones, Lyndon W
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.
Lee, Ga-Hyun; Yu, Hak-Sun; Lee, Ji-Eun
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.
Gaiser, Hilary; Ho, Connie; Janier, Nicole; Wee, Amy; Johnson, Catherine; Watanabe, Ronald
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
Maulvi, Furqan A; Desai, Ankita R; Choksi, Harsh H; Patil, Rahul J; Ranch, Ketan M; Vyas, Bhavin A; Shah, Dinesh O
The effect of surfactant chain lengths [sodium caprylate (C8), Tween 20 (C12), Tween 80 (C18)] and the molecular weight of block copolymers [Pluronic F68 and Pluronic F 127] were studied to determine the stability of the microemulsion and its effect on release kinetics from cyclosporine-loaded microemulsion-laden hydrogel contact lenses in this work. Globule size and dilution tests (transmittance) suggested that the stability of the microemulsion increases with increase in the carbon chain lengths of surfactants and the molecular weight of pluronics. The optical transmittance of direct drug-laden contact lenses [DL-100] was low due to the precipitation of hydrophobic drugs in the lenses, while in microemulsion-laden lenses, the transmittance was improved when stability of the microemulsion was achieved. The results of in vitro release kinetics revealed that drug release was sustained to a greater extent as the stability of microemulsion was improved as well. This was evident in batch PF127-T80, which showed sustained release for 15days in comparison to batch DL-100, which showed release up to 7days. An in vivo drug release study in rabbit tear fluid showed significant increase in mean residence time (MRT) and area under curve (AUC) with PF-127-T80 lenses (stable microemulsion) in comparison to PF-68-SC lenses (unstable microemulsion) and DL-100 lenses. This study revealed the correlation between the stability of microemulsion and the release kinetics of drugs from contact lenses. Thus, it was inferred that the stable microemulsion batches sustained the release of hydrophobic drugs, such as cyclosporine from contact lenses for an extended period of time without altering critical lens properties. Copyright © 2017 Elsevier B.V. All rights reserved.
Alvarez-Lorenzo, Carmen; Hiratani, Haruyiki; Gómez-Amoza, José Luis; Martínez-Pacheco, Ramón; Souto, Consuelo; Concheiro, Angel
The aim of this work was to evaluate the influence of the composition and the application of an imprinting technique on the loading capability of weakly crosslinked hydroxyethyl methacrylate (HEMA) hydrogels, with a view to their use as reloadable soft contact lenses for administration of timolol. Hydrogels were prepared by dissolution of ethylene glycol dimethacrylate (EGDMA, 10 mM) in HEMA with or without methacrylic acid (MAA) or methyl methacrylate (MMA; 100-400 mM) and with or without timolol maleate (10 mg/mL), initiation of polymerization by addition of 2,2'-azo-bis(isobutyronitrile) (AIBN, 10 mM), injection in molds, and curing in an oven at 50-70 degrees C. Unreacted reagents were removed by boiling. The dry hydrogels were clear and fully polymerized with smooth, poreless surfaces and presented optimal mechanical properties. The hydrogels were then characterized by determination of their swelling and timolol release kinetics in 0.9% NaCl, phosphate buffer (pH 7.4) and artificial lacrimal fluid, and of the timolol loading capacity of both nonimprinted hydrogels and de-timololized imprinted hydrogels at various pHs. Both water uptake and timolol release exhibited Fickian kinetics, except in the case of hydrogels made with 400 mM MAA. Timolol diffusion into 0.9% NaCl from HEMA or HEMA/MMA was slow; release from HEMA/MAA into phosphate buffer or lacrimal fluid was faster and increased with the MAA content of the polymer. Timolol loading was significant for HEMA/MAA hydrogels (imprinted or not) at pH 5.5-7.5, and specially for imprinted hydrogels containing 100 mM MAA, which absorb 12 mg timolol/g dry hydrogel. The results indicate that the incorporation of MAA as comonomer increases the timolol loading capacity to therapeutically useful levels while retaining appropriate release characteristics. Copyright 2002 Wiley-Liss Inc. and the American Pharmaceutical Association
Sulley, Anna; Young, Graeme; Lorenz, Kathrine Osborn; Hunt, Chris
To evaluate the ease with which astigmats from three groups of current non-wearers of toric contact lenses can be fitted with current toric soft lenses, and to determine toric lens-wearing success. This was a 1-month, randomized, bilateral, open-label, daily wear study involving 200 subjects and 16 investigational sites in the UK. Three groups of astigmatic subjects aged from 16 to 60 and with a mean age of 36 years (67 spherical soft contact lens users, SW; 72 contact lens drop-outs, DO; and 61 neophytes, Neo) were fitted with one of two toric soft lens types: a daily disposable toric soft lens (1 Day Acuvue Moist for Astigmatism, Johnson & Johnson Vision Care) or a 2-weekly replacement, re-usable toric soft lens (Acuvue Oasys for Astigmatism, Johnson & Johnson Vision Care). Subjects were evaluated after 1 month of wear and success rates calculated according to pre-set criteria for acceptable fit, orientation stability, visual acuity, quality of vision, and overall comfort. Eighty-eight percent of lenses were fitted at the first attempt. Of 198 subjects dispensed with lenses, 182 (92%) completed the study. When analysed by subject group, the success rates according to the pre-set criteria were 80% (53/66), 74% (52/70), and 70% (39/56) for the SW, DO and Neo groups respectively. Comfort was the most common reason for failure with all three groups; however, visual problems were more common in the DO and Neo groups (13% vs 6%). VA with the study lenses was significantly better in the SW group compared to their habitual lenses. For the DO and Neo groups combined (i.e. spectacle wearers), visual acuity was comparable to their habitual spectacles. A high proportion of astigmats who are not using toric soft contact lenses can be fitted with current lenses. Previous contact lens drop-outs and neophyte wearers achieve visual acuity comparable to spectacles when fitted with toric soft lenses. Spherical contact lens wearing astigmats achieve superior visual acuity when
Kazanci, Burcu; Ozek, Dilay; Anayol, Alparslan; Balikçi, Ayşe; Ileri, Dilek; Yilmazbaş, Pelin
To show applications of different types of gas-permeable contact lenses in patients with keratoconus and to compare visual acuity (VA) results. A total of 229 eyes of 133 patients who used different types of rigid gas-permeable contact lenses between April 2003 and April 2010 at the Cornea and Contact Lens Unit of Eye Clinic 2 of the Ministry of Health, Ulucanlar Eye Training and Research Hospital, were included. Visual acuity of patients was classified as uncorrected and corrected with eyeglasses and corrected with contact lenses. The patients were compared in terms of VA, daily contact lens wear time, and complications. A total of 70 out of 133 (52.6%) patients in our study were male, and 63 (47.4%) were female. The mean age was 25.9 ± 7.03 years (12-45). As for the classification of the 229 eyes included in the study, 136 of 229 (59.4%) eyes had moderate keratoconus, 88 (38.4%) had advanced keratoconus, and 5 (2.2%) had severe keratoconus. Following the contact lens application, the VA in all patients increased when compared to uncorrected and corrected with eyeglasses groups and the difference was statistically significant (p<0.005). When a comparison of different types of contact lenses was made, a statistically significant difference was not found (p>0.5) in terms of increase in VA. When patients were evaluated in terms of contact lens wear times, it was observed that Boston Equalens II was preferred by patients wearing lenses 4-8 hours/day. For patients wearing lenses more than 8 hours a day, Rose K lens was used the most. No serious complication was observed in any of the patients that would lead them to stop wearing contact lenses during the follow-up period. There was also no need for keratoplasty in any patient during the follow-up period. We detected an increase in VA in patients with rigid contact lenses. In addition, some contact lenses were better tolerated by patients and were used for a longer time during the day.
Choo, Jennifer; Vuu, Kathy; Bergenske, Peter; Burnham, Kara; Smythe, Jennifer; Caroline, Patrick
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.
Filipecki, J; Sitarz, M; Kocela, A; Kotynia, K; Jelen, P; Filipecka, K; Gaweda, M
Determination of free volume holes of the hydrogel and silicone-hydrogel polymer contact lenses were investigated. Two types of polymer contact lenses were used as materials: the first is a hydrogel contact lenses Proclear family (Omafilcon A), while the second is a silicone-hydrogel contact lens of the family Biofinity (Comfilcon A). Positron annihilation lifetime spectroscopy PALS was used to characterize geometrical sizes and fraction of the free volume holes in the investigated samples. There is a clear difference in the free volume sizes and their fractions between silicone-hydrogel and polymer hydrogel contact lenses which in turn are connected with oxygen permeability in these lenses. Apart from that, spectroscopic (middle infrared) MIR and Raman examinations were carried out in order to demonstrate the differences of the water content in the test contact lenses. Copyright © 2014 Elsevier B.V. All rights reserved.
Filipecki, J.; Sitarz, M.; Kocela, A.; Kotynia, K.; Jelen, P.; Filipecka, K.; Gaweda, M.
Determination of free volume holes of the hydrogel and silicone-hydrogel polymer contact lenses were investigated. Two types of polymer contact lenses were used as materials: the first is a hydrogel contact lenses Proclear family (Omafilcon A), while the second is a silicone-hydrogel contact lens of the family Biofinity (Comfilcon A). Positron annihilation lifetime spectroscopy PALS was used to characterize geometrical sizes and fraction of the free volume holes in the investigated samples. There is a clear difference in the free volume sizes and their fractions between silicone-hydrogel and polymer hydrogel contact lenses which in turn are connected with oxygen permeability in these lenses. Apart from that, spectroscopic (middle infrared) MIR and Raman examinations were carried out in order to demonstrate the differences of the water content in the test contact lenses.
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Lin, Meng C; Svitova, Tatyana F
To investigate the release of surface-active agents (surfactants) from unworn soft contact lenses (SCLs) and their influence on the lens surface wettability in vitro. 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 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 1 week. Lens surface wettability was expressed as adhesion energy according to Young equation. 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 for all studied lenses and advancing CAs of selected lenses increased (p < 0.001). Receding CAs of all studied lenses were 12 degrees +/- 5 degrees 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 silicone hydrogel lenses exhibited stable and self-sustained surface wettability in vitro. The manufacturer-added surfactants affected wetting properties of all studied SCLs, although to different degrees.
Tsukiyama, Junko; Miyamoto, Yuko; Kodama, Aya; Fukuda, Masahiko; Shimomura, Yoshikazu
Previous reports showed that cosmetic cleansing oil for removing makeup, which contains mineral oil and surfactant, can deform some silicone hydrogel contact lenses (SHCLs) when applied directly to the lenses, although plasma-coated SHCLs (lotrafilcon A and B) were not affected. In the present study, we investigated hydrogel lenses and SHCLs in both wet and dry conditions. Several brands of hydrogel and SHCLs were immersed in a cleansing oil solution containing Sudan Black B for 5 min under wet and dry conditions. The lenses under the wet condition were simply picked up from the saline, whereas those under the dry condition were blotted with paper wipes. After immersing, the excess solution remaining on the lenses was removed by finger rubbing with a multipurpose solution. The lenses were then examined using a stereomicroscope, and their mean brightness was measured and compared. The cosmetic cleansing oil was not absorbed by the hydrogel lenses under wet or dry conditions. However, four of seven brands of SHCLs absorbed the cosmetic cleansing oil under both conditions (dry and wet), whereas asmofilcon A absorbed it only under the dry condition. Lotrafilcon B and delefilcon A did not absorb cleansing oil even under the dry condition. Hydrogel lenses resist cosmetic cleansing oil. However, SHCLs have different degrees of resistance depending on the lens material. Some SHCLs absorbed cosmetic cleansing oil more under dry conditions than under wet conditions.
In 3 patients with status after Fuchs-Steven-Johnson syndrome highly hydrophilic contact lenses (72% H2O-up take) were adapted and worn permanently. 2 patients had worn already for a long time usual HEMA-lenses. The lenses showed themselves to be favorable against mechanical irritation from cilia and accessory eyelashes and from scarring conjunctival conditions, and they affected favorably the signs of dessication of the cornea. Corneal defects healed, and the patients had subjectively no complaints. It is sometimes necessary to replace the tears. An increase in the corneal vascularisation already present could not be observed during the 18 months observation time.
Hsu, Kuan-Hui; Carbia, Blanca E; Plummer, Caryn; Chauhan, Anuj
Glaucoma patients frequently instill eye drops multiple times each day, which is a cause for reduced compliance. Additionally, eye drops suffer from other limitations including low bioavailability, which can lead to side effects. We propose to develop drug-eluting contact lenses for managing glaucoma with increased bioavailability and improved compliance. Contact lenses are developed for extended simultaneous release of timolol and dorzolamide, both of which are commonly prescribed hydrophilic drugs. The extended release is achieved by loading lenses with vitamin E barriers. In vitro release studies are performed with control and vitamin E loaded lenses for both drugs loaded separately and then together in the same lens. The safety and efficacy of combination therapy by contacts are demonstrated in a Beagle model of glaucoma. Simultaneous loading of timolol and dorzolamide increases the release duration of both drugs. Also vitamin E incorporation is highly effective in increasing the release durations of both drugs to about 2-days. The lenses loaded with both drugs exhibited superior IOP reduction compared to eye drops with about 6-fold lower drug loading. More importantly, combination therapy by continuous wear of vitamin E loaded contact for 2-days, followed by a new set of contacts for another two days, reduced IOP during the 4days of wear time and for another 8days after removal of the contacts. Vitamin E loading is very effective for providing combination therapy by contact lenses due to the increase in release durations of several drugs. The contact lens based therapy reduces IOP with lower drug dose compared to eye drops and may significantly improve the compliance as the effect of the therapy lasts significantly longer than the wear-duration. Copyright © 2015 Elsevier B.V. All rights reserved.
Insua Pereira, Eduardo; Lira, Madalena
The objective of this investigation was to evaluate the level of comfort and ocular dryness during wear with six daily disposable contact lenses (DDCL) and also determine the changes in contact lens equilibrium water content (EWC) resulting from their wear. In this contralateral open trial, 27 subjects were randomly fitted with six DDCL (stenfilcon A, delefilcon A, nelfilcon A, narafilcon A, nesofilcon A, and omafilcon A). The evaluation of comfort and ocular dryness sensation was recorded by the participants at two moments of the day (11 AM and 5 PM) over a period of 10 days of contact lens wear. The assessment was made with the aid of visual analogue scales (0-10). The refractive index of 54 contact lenses was accessed by a single operator using a digital automated refractometer (CLR 12-70; Index Instruments). The EWC of the lenses was estimated based on its refractive index values. Comfort ratings were slightly higher for delefilcon A (9.56±0.67, P=0.01) and narafilcon A (9.40±0.93, P=0.01) and these lenses wearers also reported less ocular dryness. The results revealed a pronounced water content reduction for omafilcon A (P=0.002), narafilcon A (P=0.008), and nesofilcon A (P=0.003). Although changes in subjective responses and EWC were distinct among the materials analyzed, all the contact lenses performed well during the 10 days of wear.
Luensmann, Doerte; Jones, Lyndon
Proteins are a key component in body fluids and adhere to most biomaterials within seconds of their exposure. The tear film consists of more than 400 different proteins, ranging in size from 10 to 2360 kDa, with a net charge of pH 1-11. Protein deposition rates on poly-2-hydroxyethyl methacrylate (pHEMA) and silicone hydrogel soft contact lenses have been determined using a number of ex vivo and in vitro experiments. Ionic, high water pHEMA-based lenses attract the highest amount of tear film protein (1300 μg/lens), due to an electrostatic attraction between the material and positively charged lysozyme. All other types of pHEMA-based lenses deposit typically less than 100 μg/lens. Silicone hydrogel lenses attract less protein than pHEMA-based materials, with <10 μg/lens for non-ionic and up to 34 μg/lens for ionic materials. Despite the low protein rates on silicone hydrogel lenses, the percentage of denatured protein is typically higher than that seen on pHEMA-based lenses. Newer approaches incorporating phosphorylcholine, polyethers or hyaluronic acid into potential contact lens materials result in reduced protein deposition rates compared to current lens materials. Copyright Â© 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Liotet, S; Warnet, V N
A study was conducted on 113 contact lens showing fungal colonies. The main genus isolated was Cepohalosporium (59.4 p. cent). Lens contamination is favoured by a major factor: contact lens spoliation, a secondary factor being inadequate contact lens maintenance. This contamination raises an economic problem, as every affected contact lens must be replaced.
Lövsund, P; Nilsson, S E; Lindh, H; Oberg, P A
Because of reports of risks associated with the use of contact lenses during exposure to welding arcs, the temperature changes in soft contact lenses were recorded in connection with certain types of welding [manual metal arc (MMA) welding, tungsten inert-gas (TIG) welding, and metal inert-gas (MIG) welding], both with free-hanging lenses and lenses applied to the eyes of anesthetized rabbits. A great increase in temperature was noted, especially with MMA welding. At a distance of 0.4 m the temperature of a lens on a rabbit eye rose from about 35 to 50 degrees C within 6 min, whereas the air temperature only increased from 23 to 30 degrees C. The increase was the greatest at the beginning of the welding period. Most of the lenses completely dried out during the experiment, and there would seem to be a potential risk that the lens would adhere to the cornea. One safety glass screen (DIN 10 A) proved effective in preventing the rise in temperature in contact lenses during MMA welding. Even though it is impossible to direct the eyes at the arc for a prolonged period of time, the use of contact lenses in connection with at least certain types of welding is not to be recommended without the use of a suitable safety glass screen (or safety glasses). With regard to the large number of particles in the welding environment, also a risk factor for contact lens wearers, it is doubtful whether even safety glasses or screens are satisfactory unless they fit closely.
Reverey, Julia F; Fromme, Roland; Leippe, Matthias; Selhuber-Unkel, Christine
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.
Pucker, Andrew D.; Thangavelu, Mirunalni
Purpose. The purpose of this work was to develop an enzymatic method of quantification of cholesterol and cholesterol esters derived from contact lenses, both in vitro and ex vivo. Methods. Lotrafilcon B (O2 Optix; CIBA Vision, Inc., Duluth, GA) and galyfilcon A (Acuvue Advance; Vistakon, Inc., Jacksonville, FL) silicone hydrogel contact lenses were independently incubated in cholesterol oleate solutions varying in concentrations. After incubation, the lenses were removed and underwent two separate 2:1 chloroform-methanol extractions. After in vitro studies, 10 human subjects wore both lotrafilcon B and galyfilcon A contact lenses for 7 days. The lenses also underwent two separate 2:1 chloroform-methanol extractions. All in vitro and ex vivo samples were quantified with a cholesterol esterase enzymatic reaction. Results. Calibration curves from quantifications of in vitro contact lens samples soaked in successively decreasing concentrations of cholesterol oleate yielded coefficients of determination (R2) of 0.99 (lotrafilcon B) and 0.97 (galyfilcon A). For in vitro contact lens samples, galyfilcon A was associated with an average cholesterol oleate extraction of 39.85 ± 48.65 μg/lens, whereas lotrafilcon B was associated with 5.86 ± 3.36 μg/lens (P = 0.05) across both extractions and all incubation concentrations. For ex vivo contact lens samples, there was significantly more cholesterol and cholesterol esters deposited on galyfilcon A (5.77 ± 1.87 μg/lens) than on lotrafilcon B (2.03 ± 1.62 μg/lens; P = 0.0005). Conclusions. This is an efficient and simple method of quantifying total cholesterol extracted from silicone hydrogel contact lenses and, potentially, the meibum and/or tear film. Certain silicone hydrogel materials demonstrate more affinity for cholesterol and its esters than do others. PMID:20089871
Pucker, Andrew D; Thangavelu, Mirunalni; Nichols, Jason J
The purpose of this work was to develop an enzymatic method of quantification of cholesterol and cholesterol esters derived from contact lenses, both in vitro and ex vivo. Lotrafilcon B (O2 Optix; CIBA Vision, Inc., Duluth, GA) and galyfilcon A (Acuvue Advance; Vistakon, Inc., Jacksonville, FL) silicone hydrogel contact lenses were independently incubated in cholesterol oleate solutions varying in concentrations. After incubation, the lenses were removed and underwent two separate 2:1 chloroform-methanol extractions. After in vitro studies, 10 human subjects wore both lotrafilcon B and galyfilcon A contact lenses for 7 days. The lenses also underwent two separate 2:1 chloroform-methanol extractions. All in vitro and ex vivo samples were quantified with a cholesterol esterase enzymatic reaction. Calibration curves from quantifications of in vitro contact lens samples soaked in successively decreasing concentrations of cholesterol oleate yielded coefficients of determination (R(2)) of 0.99 (lotrafilcon B) and 0.97 (galyfilcon A). For in vitro contact lens samples, galyfilcon A was associated with an average cholesterol oleate extraction of 39.85 +/- 48.65 microg/lens, whereas lotrafilcon B was associated with 5.86 +/- 3.36 microg/lens (P = 0.05) across both extractions and all incubation concentrations. For ex vivo contact lens samples, there was significantly more cholesterol and cholesterol esters deposited on galyfilcon A (5.77 +/- 1.87 microg/lens) than on lotrafilcon B (2.03 +/- 1.62 microg/lens; P = 0.0005). This is an efficient and simple method of quantifying total cholesterol extracted from silicone hydrogel contact lenses and, potentially, the meibum and/or tear film. Certain silicone hydrogel materials demonstrate more affinity for cholesterol and its esters than do others.
Fedtke, Cathleen; Bakaraju, Ravi C; Ehrmann, Klaus; Chung, Jiyoon; Thomas, Varghese; Holden, Brien A
To assess visual performance of single vision and multifocal soft contact lenses. At baseline, forty-four myopic participants (aged 18-35 years) were fitted bilaterally with a control lens (AirOptix Aqua). At the four follow-up visits, a total of 16 study lenses (5 single vision, 11 multifocal lenses) were fitted contralaterally. After 1h of lens wear, participants rated (scale 1-10) vision clarity (distance, intermediate and near), magnitude of ghosting at distance, comfort during head movement, and overall comfort. Distance high contrast visual acuity (HCVA), central refraction and higher order aberrations, and contact lens centration were measured. For single vision lenses, vision ratings were not significantly different to the control (p>0.005). The control outperformed Acuvue Oasys, Clariti Monthly and Night and Day in HCVA (mean VA: -0.10 ± 0.07 logMAR, p<0.005). Most refraction and higher order aberration measures were not different between lenses. The Night and Day lens showed greatest differences compared to the control, i.e., C[4, 0] was more positive (p<0.005) at distance (Δ=0.019 μm) and near (Δ=0.028 μm). For multifocal lenses, the majority of vision ratings (84%) were better with the control (p<0.005). HCVA was better with the control (p<0.005). Proclear Multifocal lenses showed greatest differences for M, C[3, -1] and C[4, 0] at distance and near, and were inferiorly de-centered (p<0.005). Design differences between single vision lenses had a small impact on visual performance. Lenses featuring multifocality decreased visual performance, in particular when power variations across the optic zone were large and/or the lens was significantly de-centered. Copyright © 2015. Published by Elsevier Ltd.
Lin, Meng C.; Svitova, Tatyana F.
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
Zhu, Qiurong; Yang, Bi; Deng, Nan; Li, Yifan; Wang, Tingwei; Qi, Huang; Liu, Longqian
To assess the prevalence and general knowledge of contact lens wearers among college students in Chengdu, a metroplolitan of Chinaand find out the routine habits of use and hygienic conditions when wearing contact lenses. The questionnaire was distributed to 1,600 ametropic participants who were from 8 different universities. Data about demographics, general contact lens handling habits, personal attitudes, hygiene behaviors and eye health conditions were collected. We made the analysis ofthe demographics and wearing of contact lenses. Possible reasons for behaviors related to the care of contact lenses were analyzed. The prevalence of contact lens use was 19.80%. Most users (82.15%) were females. An aesthetic effect was cited as the first reason for using (57.91%). The comfort of eyes was the first consideration (75.76%) when buying. To keep clean and use safe, 86.20% subjects washed hands before handling and 83.50% cleaned the lens carefully after removing. There was significant difference between males and females regarding the replacement of the solution (p=0.014). 32.66% wears knew the removal of protein deposits. A total of 54.88% were not informed of the potential complications of contact lens. The incidence of ocular discomfort was 44.78%. Only 3.03% of the students paid regular visits to ophthalmic clinics. The prevalence of contact lenses was relatively low in Chengdu. The wears had limited knowledge about using and careof contact lens. More education on standard lens wear and care should be provided to wearers. Copyright © 2017. Published by Elsevier Ltd.
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
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.
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
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
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
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.
Lövsund, P; Nilsson, S E; Oberg, P A
A number of reports have appeared over the past few years with warnings about the wearing of contact lenses in certain trades involving exposure to are flash. In view of these reports and in light of knowledge on the marked absorption by contact lenses, within the infrared (IR) region, temperature changes were measured in soft contact lenses under radiation from IR heaters used, for example, in the motor industry for drying paint. The lenses were tested while free-hanging and when applied to rabbit eyes. Great increases in temperature were noted with one of the heaters at a distance corresponding to "safe." During 10 min of exposure the temperature of a free-hanging lens rose from 21 to 59 degrees C, whereas the temperature in the surrounding air increased only from 26 to 30 degrees C. The final temperature of the lens was thus 29 degrees C higher than that of the air. In lenses applied to rabbit eyes the temperature rose within only 0.5, 1.0, and 1.5 min from approximately 33 degrees C to about 44, 49, and 51 degrees C, respectively; the air temperature rose from 25 to only 28 degrees C. In other words, the ultimate lens temperature was 23 degrees C higher than the ambient air temperature. In the rabbit experiments most of the lenses dried out completely. There would thus seem to be considerable risk of contact lenses drying and becoming adherent to and damaging the corneal surface among workers exposed to powerful radiation from IR radiators (IR heaters), unless they use efficient eye protectors. IR heaters appear to be associated with greater hazards than are flashes, since there is no warning from powerful visible light and because they are capable of causing a very rapid increase in temperature.
Nakagawara, Van B; Wood, Kathryn J; Montgomery, Ron W
Since 1976, the use of contact lenses by civilian pilots has been permitted to correct distant vision for obtaining a Federal Aviation Administration (FAA) aeromedical certificate. This study examined the civil airman population's experience with contact lens use for a 30-year period (1967 to 1997). Population totals for airmen who carried pathology codes 161 (contact lens) and 158 (orthokeratology) from January 1, 1967 through December 31, 1997 were used to calculate prevalence rates by class of medical certificate and age. The National Transportation Safety Board and FAA databases were queried to determine if contact lens use had contributed to aviation mishaps. The prevalence of contact lens use grew faster for first-class medical certificate holders and airmen > or = 40 years of age during the period. The frequency of airmen with orthokeratology increased by 23 times in a 10-year period. Reports from five aviation accidents and one incident suggested that contact lens use was a contributing factor in these mishaps. Professional pilots and older airmen were found to be more inclined to use contact lenses. The increasing use of contact lenses and the rapid changes in contact lens technology warrant continued monitoring to ensure aviation safety.
Tomlinson, A; Bibby, M M
Control of the movement of a contact lens on the eye is of particular importance in the case of a toric lens fitted on a toroidal cornea. Lens rotation was measured on 13 eyes fitted with each of three types of spherical contact lenses, regular, prism ballasted-truncated, and truncated only. Edge lift was varied in three steps, and lenses fitted flat and steep were tested for the amount of blink-associated rotation. Rotation can be reduced by decreasing the radius of the base curve or providing truncation and/or prism ballast.
Alipur, Fateme; Hosseini, Seyedeh Simindokht
To evaluate visual results, comfort of use, safety, and efficacy of mini scleral contact lenses in optical management in patients with traumatic aphakia and severe concomitant irido-corneal injury. In a case series, eight eyes with post traumatic aphakia and severe concomitant irido-corneal injury that were evaluated at the Contact Lens Clinic of Farabi Eye Hospital, Tehran, Iran for contact lens fitting and could not be corrected with conventional corneal RGP contact lenses were fitted with miniscleral contact lenses. Uncorrected visual acuity (UCVA), best spectacle corrected visual acuity (BSCVA), and BCVA (Best corrected visual acuity) with miniscleral lens were recorded. Slit lamp examination, comfortable daily wearing time, and any contact lens-related complication were documented in each follow-up visit. The mean UCVA and BSCVA of the cases was >2.7 and 0.41 LogMAR, respectively (BSCVA could not be assessed in one case due to severe corneal irregularity). The mean final BCVA with the miniscleral lens was 0.05 LogMAR (range from 0.4 to -0.04 LogMAR). The mean follow-up period was 14.6 months. The mean comfortable daily wearing time (CDWT) was 11.6 h, ranging from 8 to 16 h. The only contact lens-related complication was mild redness and irritation that was observed in 2 patients during the follow-up visits. All patients were comfortable with handling these lenses. Miniscleral contact lenses can be considered a safe and effective option in aphakia patients with concurrent corneal scarring secondary to ocular injury for whom surgical intervention would be complicated.
Cabrera, Josefa Velasco; Velasco, María José García
The aim of the present study is to determine the amount and time of water-content recovery of ionic contact lenses (Surevue and Acuvue) and non-ionic contact lenses (Soflens 38, Soflens 66 and Optima 38) when submerged in maintenance solution for 9 h. Using a hand-held refractometer, we measured the water content of the lenses upon removal from the eye, and after 15, 30, 45 min, 1, 2 and 9 h in soaking solution. Both ionic lenses presented pre-wear water content of 58%, while two of the non-ionic ones (Soflens 38 and Optima 38) registered 38.6% and the third (Soflens 66) had 66%. We found a significant increase (p < 0.05) in water content after submersion in the Opti-Free solution for all the time periods studied and for all lenses. The water-content recovery was faster in the non-ionic lenses (Soflens 38, Soflens 66 and Optima 38) than in the ionic ones (Surevue and Acuvue), especially at 15 min. After 9 h in the soaking solution, the Surevue Acuvue, Soflens 38, Soflens 66 and Optima 38 lenses reached water-content recovery values of 99.7%, 99.6%, 99.8%, 99.8% and 99.6%, respectively, without significant differences (p > 0.05) between ionic and non-ionic lenses, although the non-ionic lenses reached slightly higher water-content values at all the times studied. These results indicate that when the refractometer technique is used to measure water content, the lens types used in this study regain their initial water-content values after 9 h in soaking solution. These data indicate the time needed for hydrogel contact lenses to reach their maximum water content after removal from the eye and submersion in maintenance solution. By ensuring maximum water content and minimum reduction of oxygen for the cornea, the specialist can help avoid clinical signs and symptoms related to low water content in the lenses.
Ben Yaish, Shai; Zlotnik, Alex; Raveh, Ido; Yehezkel, Oren; Belkin, Michael; Lahav, Karen; Zalevsky, Zeev
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.
Kackar, Siddharth; Suman, Ethel; Kotian, M Shashidhar
Microbial biofilm formation on contact lenses and lens storage cases may be a risk factor for contact lens-associated corneal infections. Various types of contact lens care solutions are used to reduce microbial growths on lenses. The present study aimed at comparing the growths of biofilms on the different contact lenses and lens cases. The study also aimed at determining the effect of lens care solutions and bacteriophage on these biofilms. One type of hard lens and two types of soft lenses were used for the study. The organisms used were Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Candida albicans ATCC 60193 and Escherichia coli ATCC 25922. Biofilm production was performed by modified O'Toole and Kolter method and effect of lens cleaning solutions and a crude coliphage on biofilms was also studied. Results were visualised using scanning electron microscopy and quantitated by colony counting method and spectrophotometric measurement of optical density (OD). Statistical analysis was done by SPSS 11.5, Kruskal-Wallis test and Chi-square test. Soft lens cleaning solutions had a significant inhibitory effect (P = 0.020) on biofilm formation on soft lenses and also lens cases (P < 0.001). Soft lens cleaning solution 2 was more efficient than solution 1. However, no such inhibitory effect was observed with regard to hard lens cleaning solution, but for a significant reduction in the OD values (P < 0.001). There was no significant inhibitory effect by bacteriophages. This study showed the importance of selecting the appropriate lens cleaning solution to prevent biofilm production on contact lenses.
Paradiso, Patrizia; Serro, Ana Paula; Saramago, Benilde; Colaço, Rogério; Chauhan, Anuj
Symptoms of bacterial and fungal keratitis are typically treated through the frequent application of antibiotic and antifungal eye drops. The high frequency of half hourly or hourly eye drop administration required to treat these indications is tedious and could reduce compliance. Here, we combine in vitro experiments with a mathematical model to develop therapeutic soft contact lenses to cure keratitis by extended release of suitable drugs. We specifically focus on increasing the release duration of levofloxacin and chlorhexidine from 1-DAY ACUVUE(®) TrueEye™ and ACUVUE OASYS(®) contact lenses by incorporating vitamin E diffusion barriers. Results show that 20% of vitamin E loading in the contact lens increases the release duration of levofloxacin to 100 h and 50 h from 1-DAY ACUVUE(®) TrueEye™ and ACUVUE OASYS(®), respectively, which is a 3- and 6-fold increase, respectively, for the 2 lenses. For chlorhexidine, the increase is 2.5- and 10-fold, for the TrueEye™ and OASYS(®), respectively, to 130 h and 170 h. The mass of drug loaded in the lenses can be controlled to achieve a daily release comparable to the commonly prescribed eye drop therapy. The vitamin E-loaded lenses retain all critical properties for in vivo use. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.
Hall, Brad; Forrest, James A; Jones, Lyndon
To compare and critically evaluate a variety of techniques to measure the quantity and biological activity of protein sorption to contact lenses over short time periods. A literature review was undertaken investigating the major techniques to measure protein sorption to soft contact lens materials, with specific reference to measuring protein directly on lenses using in situ, ex situ, protein structural, and biological activity techniques. The use of in situ techniques to measure protein quantity provides excellent sensitivity, but many are not directly applicable to contact lenses. Many ex situ techniques struggle to measure all sorbed proteins, and these measurements can have significant signal interference from the lens materials themselves. Techniques measuring the secondary and tertiary structures of sorbed proteins have exhibited only limited success. There are a wide variety of techniques to measure both the amount of protein and the biological activity of protein sorbed to soft contact lens materials. To measure the mass of protein sorbed to soft contact lenses (not just thin films) over short time periods, the method of choice should be I radiolabeling. This technique is sensitive enough to measure small amounts of deposited protein, provided steps are taken to limit and measure any interaction of the iodine tracer with the materials. To measure the protein activity over short time periods, the method of choice should be to measure the biological function of sorbed proteins. This may require new methods or adaptations of existing ones.
Kollbaum, Pete S.; Bradley, Arthur; Thibos, Larry N.
Purpose The purpose of the current study was to examine the on- and off-eye optical performance of two types of soft contact lenses (hydrogel and silicone hydrogel). Methods The monochromatic aberrations (lambda = 850 nm) of contact lenses were measured on-eye using a clinical Shack-Hartmann ocular aberrometer. Additionally, we used an off-eye single-pass contact lens aberrometer (lambda = 540 nm) in which the soft contact lens was placed within a wet cell. Comparison of the lower and higher order aberrations measured with these two methods required compensation for different wavelengths and knowledge of the refractive index of the contact lens materials. Results The measured on-eye sphere and spherical aberration values were generally similar to those measured off-eye and those specified by the lens manufacturers for both types of soft contact lenses. However, there were notable differences, especially for high plus-powered lenses, which typically exhibited lower sphere power on the eye than expected from the lens specifications and from the off-eye measured powers, both of which were almost identical. Longitudinal spherical aberration varied with lens power in the hydrogel lenses, as expected from geometrical optics theory. Longitudinal spherical aberration measurements on- and off-eye, however, deviated significantly from that expected of a thin lens with spherical surfaces due to surface asphericities. The difference between on- and off-eye optics can be modeled as a tear lens, or as relative lens thickness changes caused by lens flexure. Conclusions The results of the current study reveal that the major difference between the on-eye lens optics and the manufacturers’ specifications are not due to lens errors, but due to eye-lens interactions, which could be either lens flexure or a tear lens forming behind the soft contact lens. PMID:23969894
Maulvi, Furqan A; Choksi, Harsh H; Desai, Ankita R; Patel, Akanksha S; Ranch, Ketan M; Vyas, Bhavin A; Shah, Dinesh O
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.
Ng, Alan; Heynen, Miriam; Luensmann, Doerte; Jones, Lyndon
To investigate the impact of lactoferrin and lipids on the kinetic deposition of lysozyme on silicone and conventional hydrogel lenses, using a complex artificial tear solution (ATS). Two silicone hydrogel lenses (AIR OPTIX AQUA; lotrafilcon B and ACUVUE OASYS; senofilcon A) and two conventional hydrogel lenses (ACUVUE 2; etafilcon A and PROCLEAR; omafilcon A) were investigated. Lenses were incubated in four different solutions: a complex ATS consisting of various salts, lipids, proteins, and mucins, an ATS without lactoferrin (ATS w/o Lac), an ATS without lipids (ATS w/o Lip), and an ATS without lactoferrin and lipids (ATS w/o Lac & Lip), each containing 2% radiolabeled (125I) lysozyme (1.9 mg/ml). After each time point (4, 12 h and 1, 2, 3, 5, 7, 14, 21, 28 days), the amount of lysozyme per lens was quantified. After 28 days, lotrafilcon B lenses incubated in ATS deposited significantly less lysozyme (9.7 ± 1.4 μg) than when incubated in solutions not containing lactoferrin and lipids (more than 11.8 μg) (p < 0.001). Lysozyme uptake to senofilcon A lenses was higher in ATS w/o Lip (5.3 ± 0.1 μg) compared with other solutions (less than 3.9 μg) (p < 0.001). Etafilcon A lenses deposited the most lysozyme in all four solutions compared with the rest of the lens types (p < 0.001). For etafilcon A lenses, less lysozyme was deposited when incubated in ATS w/o Lip (588.6 ± 0.4 μg) compared with the other solutions (more than 642.6 μg) (p < 0.001). Omafilcon A lenses in ATS w/o Lac accumulated significantly less lysozyme (12.8 ± 1.0 μg) compared with the other solutions (more than 14.2 μg) (p < 0.001). An ATS containing lactoferrin and lipids impacts lysozyme deposition on both silicone and conventional hydrogel contact lenses. When performing in vitro experiments to study protein deposition on contact lenses, more complex models should be used to better mimic the human tear film.
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
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
Wei, Xiaojia; Aliwarga, Yulina; Carnt, Nicole A.; Garrett, Qian; Willcox, Mark D.P.
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
Remba, M J
Three toric hydrogel contact lenses have been approved by the FDA, Durasoft TT, Hydromarc, and Hydrocurve II. These all incorporate prism ballast as the major axis stabilizing feature, but differ in diameter and placement of the cylinder. Correct cylinder axis positioning and maintenance of meridional stability are essential to fitting success.
Pedrotti, M; Guerra, G F
In a study concerning 124 eyes, we have considered the frequency of superficial deposits on gas-permeable contact lenses in extended wear. On the whole this is not a serious problem when a regular and complete upkeep is made. The new materials made with fluor have proven to be superior to materials made with silicones.
Quesnel, N M; Fares, F; Verret, E; Giasson, C
Increasing evidence suggesting deleterious effects of ultraviolet radiation (UVR) on the eye has prompted manufacturers to develop UV-absorbing disposable contact lenses. The spectral transmittances of a sample of these lenses were measured in order to determine if they provide adequate protection from UVR. Four types of UV-absorbing disposable lenses were studied (Acuvue [Vistakon, Jacksonville, FL], Precision UV [Wesley-Jessen, Des Plaines, IL], Specialty Sport [Specialty UltraVision, Sunnyvale, CA], and Surevue [Vistakon]). For comparison, a lens without UV-absorbing properties (Acuvue), a conventional soft lens (Permaflex UV [Cooper Vision, San Jose, CA]) and an RGP lens (Boston ES [Polymer Technology, Rochester, NY]) were also evaluated. The tested lens was placed in a silica wet cell filled with saline. Spectral transmittance was measured over the 200-800 nm waveband. Each disposable lens exhibited a transmittance window in the 240-320 nm waveband. Computing indices of protection factor and safe exposure duration allowed for the assessment of the level of protection afforded by each lens. Among disposable lenses studied, the Surevue performed best with a transmittance of less than 1% in the waveband 280-348 nm and the longest safe exposure duration, while the Specialty Sport had the highesttransmittance of UVB (290-315 nm). All UV-absorbing lenses studied provided a better level of protection from UVR exposure than lenses without UV absorber. These results will help the eyecare practitioner in prescribing the most appropriate UV-blocking lens for each patient.
Koffler, Bruce H; Sears, James J
To compare the safety and efficacy of orthokeratology as a nonsurgical treatment for myopia in children with alternate methods, such as soft contact lenses, rigid gas permeable lenses, and spectacles, throughout multiple studies. Perspective with literature review. Analysis of recent studies to determine the safety and effectiveness of orthokeratology versus soft contact lenses, rigid gas permeable lenses, and spectacles in children. In all of the studies reviewed, the use of orthokeratology lenses proved to reduce myopia, to improve visual acuity, and, with the exception of the SMART study, to reduce the rate of axial elongation. Orthokeratology has been shown to be as effective as other methods in treating myopia and to be more effective at treating axial elongation. There were no major adverse events in any of the studies comparing orthokeratology with other methods of myopia treatment. Studies show that the use of orthokeratology is a safe and efficacious nonsurgical treatment for myopia and that it is capable of slowing axial elongation, making it an effective myopic treatment for children. Copyright © 2013 Elsevier Inc. All rights reserved.
Momeni-Moghaddam, Hamed; Naroo, Shehzad A; Askarizadeh, Farshad; Tahmasebi, Fatemeh
To compare lens orientation and rotational recovery of five currently available soft toric lenses. Twenty subjects were recruited and trialed with each of the study lenses in a random order. Study lenses were PureVision(®) Toric (B&L), Air Optix(®) for Astigmatism (Alcon), Biofinity(®) Toric (CooperVision), Acuvue(®) Advance for Astigmatism (Vistakon), and Proclear(®) Toric (CooperVision). Lens orientation in primary position to determine the lens rotation form the vertical position and rotational recovery to primary gaze orientation following a 45° manual misorientation for the different lenses was compared. The Biofinity Toric showed the lowest rotation from the vertical position and the Proclear Toric the highest. Also, the highest and the lowest reorientation speed were related to the Biofinity Toric and the Acuvue Advance for Astigmatism, respectively. The Repeated Measures ANOVA showed a significant difference in the lens rotation (P=0.004) and rotational recovery (P<0.001) among different contact lenses and the performed multiple comparisons indicated differences in rotation and also in reorientation speed were only seen between the Biofinity Toric when compared to four other lenses (P<0.05). Although there was appropriate fitting, based upon lens orientation and reorientation speed, with each of the study lenses it would appear that the optimized ballast technique used in the design of the Biofinity Toric helps reduce lens rotation and improve rotational recovery compared to others. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
González-Méijome, J M; López-Alemany, A; Almeida, J B; Parafita, M A
To evaluate the effect of wear on dynamic in vitro dehydration of silicone hydrogel (Si-Hi) contact lens (CL) using a previously described gravimetric procedure. Five different silicone hydrogel (Si-Hi) contact lenses (CL) were evaluated after being worn by patients under daily wear conditions for 15 days to 1 month. Lenses were conditioned and disinfected with a multipurpose solution after each day of wear. Lenses were left to dehydrate in an analytical balance under controlled conditions of temperature and relative humidity and the results compared with data from new lens samples of the same power and material. Several quantitative parameters were obtained and compared between worn and unworn samples. The quantitative parameters derived from the dehydration curves showed statistically significant differences between worn and unworn lenses regarding the initial dehydration rate and ability to maintain their original hydration. Worn lenses showed shorter phase I duration (decreased by 30 to 60% compared to unworn samples), a significantly faster initial dehydration rate (increased by about 1%/minute), and lower water retention index (decreased by 10 to 20%) as derived from the initial cumulative dehydration. All the differences were statistically significant for all lenses (p < 0.05). The initial dehydration rates were significantly increased in all CL after wear. This could be of clinical interest because it represents the average initial dehydration rates during the first moments when the lens is left to dehydrate after a blink. This study suggests that even after the lenses had been equilibrated in saline solution for several days, the materials lose their ability to retain water. (c) 2008 Wiley Periodicals, Inc.
Abdi, Saber; Thunholm-Henriksson, Inga-Lill; Pansell, Tony
The aim was to present a series of patients with intermittent partially accommodative esotropia (pAcc-ET) in evaluating the effect of over-plus correcting the hypermetropia relative to the non-cycloplegic refraction using contact lenses. Twenty-three patients (23.8 ± 8.9 years) with intermittent pAcc-ET were fitted with soft daily single-vision contact lenses and the hypermetropia was over-plus corrected relative to the original subjective non-cycloplegic refraction, reducing distance visual acuity to 0.8 (decimal acuity). Hypermetropia correction was increased at follow-ups (every second week) until visual acuity stabilised or symptoms ceased. The contact lenses were worn for the entire study period. After eight weeks of treatment (two to four follow-ups) the intermittent esotropia stabilised into esophoria and the magnitude of the deviation at distance was reduced in 70 per cent (16/23) of patients and at near in 91 per cent (21/23) of patients. As a result calculated accommodative-convergence and the level of accommodation (stimulus AC/A ratio) was reduced in 83 per cent (19/23) of patients but still classified as high (less than 5:1). Compared to correction based on original non-cycloplegic subjective refraction, increasing correction of hypermetropia with contact lenses in partially accommodative esotropia reduced the magnitude of the eso-deviation at distance and near. In addition to reducing accommodative demand and stimulus AC/A with increasing hyperopic correction, contact lenses may provide additional benefit given the increased hyperopic correction and the decreased stimulus for accommodation required at the corneal plane. © 2016 The Authors. Clinical and Experimental Optometry © 2016 Optometry Australia.
Rodriguez-Vallejo, Manuel; Benlloch, Josefa; Pons, Amparo; Monsoriu, Juan A; Furlan, Walter D
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.
Pucker, Andrew D.; Nichols, Jason J.
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
Chan, Ka Yin; Cheung, Sin Wan; Cho, Pauline
The aim was to compare the thickness of each corneal sublayer and the visualization of superficial epithelial cells measured with the ConfoScan 4 (CS4) z-ring with and without the use of a soft contact lens and to evaluate the recovery rate of corneal staining after measurement with the CS4 (z-ring) with and without the application of artificial tears (ATs). Twenty-eight subjects aged 18 to 35 years were recruited to have measurements with the CS4 (z-ring) on 2 different days. The measurements were performed over soft contact lenses (hydrogel lens or silicone hydrogel lens) on the first day and on the naked cornea on the second day. The recovery rates of the corneal staining induced by the measurements at the second visit were monitored for 5 hrs after measurements, one eye with the application of ATs and one eye without. No significant differences were found in the thicknesses of the central cornea and the sublayers measured with or without soft contact lenses. The intensity of epithelial cell images was improved with measurement made over hydrogel lenses, and on average, grade 3 (coverage) staining was observed in the corneas immediately after measurements without contact lenses. The recovery rate of the corneal staining did not improve with the application of ATs. Thickness measurements with the CS4 (z-ring) were not affected if made over soft contact lenses. The use of a soft lens to buffer the cornea during measurements was effective in eliminating corneal dehydration, preventing staining induced by the z-ring without affecting the corneal thickness measurement. It also enhanced epithelial image brightness, which may improve the accuracy in pachymetry.
Pucker, Andrew D; Nichols, Jason J
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. After informed consent, subjects were fitted with lotrafilcon B contact lenses (CIBA Vision). 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) 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 on removal from the eyes. Protein was extracted with a 50:50 0.2% trifluoroacetic acid-acetonitrile solution and quantified using a Bradford analyses. Twenty contact lens wearers were enrolled in this study. For the non-rinsed lenses, the first extraction yielded 13.4 +/- 9.2 microg/lens of protein, whereas the second extraction yielded 5.8 +/- 2.8 microg/lens of protein. For the rinsed lenses, the first extraction yielded an average of 3.0 +/- 1.9 microg/lens of protein, whereas the second extraction yielded an average of 4.0 +/- 2.3 microg/lens. Repeated measures analysis of variance showed a significant interaction (F-statistic = 18.9, p < 0.0001) between the rinse of a lens and extraction number. Rinsing a contact lens after removal from the eye removes well more than one-half of the protein associated with it. Further, to biochemically recover all protein from a silicone hydrogel lens, it may be important to perform more than one chemical extraction from it.
Lira, M; Santos, L; Azeredo, J; Yebra-Pimentel, E; Real Oliveira, M E C D
The purpose of this work was to evaluate the ability of four silicone-hydrogel contact lenses (galyfilcon A, balafilcon A, lotrafilcon A and lotrafilcon B) to retain their equilibrium water content before and after wear, through measurements of refractive index and compare with that of a conventional disposable hydrogel contact lens (etafilcon A). The refractive indices of 115 contact lenses were measured using an automated refractometer (CLR 12-70, Index Instruments, Cambridge, U.K.) before and after a schedule of daily wear by 58 patients for 30 days in the case of silicone-hydrogel lenses and 15 days for the conventional contact lenses. In the silicone-hydrogel contact lenses the changes on the refractive indices were not statistically significant, however after being worn the refractive index of the conventional etalfilcon A hydrogel contact lens increased significantly (p<0.001). The results presented here show that after being worn the silicone-hydrogel contact lens, show more capacity to retain or to reach their initial equilibrium water content than conventional hydrogel contact lenses. This suggests that the silicone-hydrogel contact lenses are less susceptible to spoilation over time maintaining its biocompatibility and contributing to the clinical success of lens performance.
Komori, Yasuka; Kobayashi, Daisuke; Murase, Yosuke; Enomoto, Itaru; Takagi, Hideki; Kono, Ichiro
This study investigated the extent of contact-lens use in Japanese college water-polo male players over 20 years (1991-2011, once every five years). Information about the use of contact lenses during play and the types of contact lens was obtained through a self-report questionnaire. The proportion of contact lens use among the players while playing water polo differed from 1991 to 2011 (χ2(4) = 25.28, P < 0.001, Cohen's d = 0.63). Fifty-four per cent of the players used contact lenses while playing in 1991 (P < 0.001); more than 74% in 1996; 89% in 2001; 84% in 2006; and 86% in 2011. While 96% of the contact lenses used by the players in 1991 were the soft type, 74%, 92%, 86%, and 88% of the contact lenses used in 1996, 2001, 2006, and 2011, respectively, were the disposable type. These findings indicated a high percentage of players were using contact lenses while playing water polo between 1996 and 2011. This could be because the majority of players used disposable lenses. The results suggest that increasing use of contact lenses by water-polo players is beneficial.
Xu, Jinku; Li, Xinsong; Sun, Fuqian
The purpose of this work was to evaluate the usefulness of silicone hydrogel contact lenses loaded with ketotifen fumarate for ocular drug delivery. First, silicone contact lenses were prepared by photopolymerization of bitelechelic methacrylated polydimethylsiloxanes macromonomer, 3-methacryloxypropyltris(trimethylsiloxy)silane, and N,N-dimethylacrylamide using ethylene glycol dimethacrylate as a cross-linker and Darocur 1173 as an initiator followed by surface plasma treatment. Then, the silicone hydrogel matrices of the contact lenses were characterized by equilibrium swelling ratio (ESR), tensile tests, ion permeability, and surface contact angle. Finally, the contact lenses were loaded with ketotifen fumarate by pre-soaking in drug solution to evaluate drug loading capacity, in vitro and in vivo release behavior of the silicone contact lenses. The results showed that ESR and ion permeability increase, and the surface contact angle and tensile strength decreased with the increase of DMA component in the silicone hydrogel. The drug loading and in vitro releases were dependent on the hydrogel composition of hydrophilic/hydrophobic phase of the contact lenses. In rabbit eyes, the pre-soaked contact lenses sustained ketotifen fumarate release for more than 24 h, which leads to a more stable drug concentration and a longer mean retention time in tear fluid than that of eye drops of 0.05%.
Michaud, Langis; Forcier, Pierre
This study aimed to compare two daily disposable lenses to reduce lens-induced discomfort (CLD) among different populations of symptomatic wearers. This was a multicenter, crossover, study. Subjects were contact lens wearers reporting CLD. Subjects (76) were randomly assigned to wear Nelfilcon A (NF) then Delefilcon A (DF)- group A- or vice-versa (group B). Tear break-up time (TBUT), corneal (CS) and conjunctival staining (CJS) were graded at every visit. Subjects'symptoms were evaluated with Contact Lens Dry Eye Questionnaire (CLDEQ-8) and a research questionnaire (Université de Montréal). Compared to baseline (BL), TBUT did not vary (BL) 6.7+2.1s vs. 6.7+1.8s (NF) vs. 6.4+1.9 (DF) (F=1.69; p=0.201) NF wearers were more at risk of developing moderate CJS (odds ratio 14.324; 95% CI 3.103-66.126) and more likely to show increased CS (odds ratio 8.754; 95% CI 2.181-35.146). Comfortable hours of wear reported at BL (7.6+2.3h) did not improve significantly with NF lenses (8.5+ 2.6h; F=1.095; p=0.394) but increased by 22% with DF lenses (10.7+3.0h; F=2.434; p=0.031). The total CLDEQ-8 score was improved with DF lenses (BL 17.2 vs. NF 16.1, p=0.397; vs. DF 8.3, p<0.001), especially on more symptomatic subjects. In the end, 92% of patients preferred to switch over DD lenses, 78% selecting DF material for the future. Outcome from switching CLD wearers to DD lenses is material related. It seems that initial severity of the symptoms could be also a factor to consider. Copyright © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Danion, Anne; Brochu, Heïdi; Martin, Yves; Vermette, Patrick
Intact liposomes were immobilized onto soft contact lenses. In the first step, polyethylenimine was covalently bounded onto the hydroxyl groups available on the surface of a commercial contact lens (Hioxifilcon B). Then, NHS-PEG-biotin molecules were bounded onto the surface amine groups by carbodiimide chemistry. NeutrAvidin were bounded onto the PEG-biotin layer. Liposomes containing PEG-biotinylated lipids were docked onto the surface-immobilized NeutrAvidin. Consecutive addition of further NeutrAvidin and liposome layers enabled fabrication of multilayers. Multilayers of liposomes were also produced by exposing contact lenses coated with NeutrAvidin to liposome aggregates produced by the addition of free biotin in solution. XPS revealed the immobilization of the different layers. By blocking with excess biotin surface-immobilized NeutrAvidin on contact lenses bearing PEG-biotin layers produced under cloud point conditions, ELISA showed that the docking of NeutrAvidin was dependent on biotin-NeutrAvidin affinity binding, with little evidence for nonspecific physisorption; however, it was not possible to differentiate specific versus nonspecific binding of NeutrAvidin attached onto PEG-biotin layers grafted without cloud point conditions. AFM imaging revealed liposome sizes of 106 and 155 nm for layers of liposomes produced (i) by the consecutive addition of further NeutrAvidin and liposomes and (ii) by the exposure of NeutrAvidin-coated contact lenses to liposome aggregates, respectively. The release kinetics of a fluorescent dye demonstrated that intact liposomes had been immobilized onto contact lens surfaces. The stability of surface-immobilized liposomes onto contact lens surfaces showed temperature dependence. Surface-bound liposomes can be stored up to 1 month at 4 degrees C with little release of their content. Copyright 2007 Wiley Periodicals, Inc.
Rad, Maryam Shayani; Sajadi Tabassi, Sayyed Abolghasem; Moghadam, Maryam Hassanpour; Mohajeri, Seyed Ahmad
Betamethasone (BMZ) is an effective drug which is commonly used as an eye drop for the management of ophthalmic inflammations. Due to low ocular bioavailability, it is necessary to prepare and optimize an ocular drug delivery system for BMZ. In this study we tried to use vitamin E diffusion barrier for sustaining BMZ release. Three commercial contact lenses were soaked in vitamin E solutions and swelling percentage, diameter, transmittance, binding capacity and release amount and time were evaluated in comparison with non-vitamin E-loaded pure lenses. The results showed that vitamin E significantly decreased water content of contact lenses whereas, increased the lens diameter in both dry and wet states. It effectively blocked UV radiation which is harmful for the eye surface while had no significant effect on visible transmittance. BMZ loading capacity enhanced and release rate remarkably decreased after using vitamin E as a hydrophobic diffusion barrier. This study revealed that vitamin E can be applied as a hydrophobic diffusion barrier for controlling and sustaining BMZ release from silicone-based soft contact lenses into the lachrymal fluid. It can also protect eye tissues as an antioxidant by blocking the UV radiation.
de Miguel, I; Ferrando, R; Santan, O E; Martín-Sánchez, A M
Keratitis by Acanthamoeba is a severe infectious complication which may be derived from the use and bad preservation of contact lens. This disease la increasingly more frequent and rapid diagnosis and treatment condition the posterior evolution of the disease. The cases of 2 contact lens waters who developed keratitis by Acanthamoeba are presented. The diagnostic methods and treatment are commented upon. Keratitis by Acanthamoeba was diagnosed in 2 patients following analysis of corneal scrapings and of the saline solution used for lens maintenance. Trophozoites and cystes of this parasite were observed in all the samples processed. The evolution was good in the patient treated at 15 days after initiation of the symptoms. However, the evolution was very bad in the patient who delayed in initiating the amebicide treatment. Penetrating keratoplasty was performed in both patients. Specific treatment with derivates of propamidine implemented early may avoid severe ocular complications. As prophylaxis for contact lens users, it is recommended that the contact lens be maintained clean and correctly care for, and the use of home-made saline solutions which are easily contaminated by Acanthamoeba, should be avoided.
Lunardi, Letícia Helena; Arroyo, Danielle; Andrade Sobrinho, Marcelo Vicente de; Lipener, César; Rosa, Juliana Maria da Silva
Keratoconus is characterized by bilateral asymmetrical corneal ectasia that leads to inferior stromal thinning and corneal protrusion. There is currently a lack of consensus regarding the most efficacious method for fitting contact lenses in patients with keratoconus, given the various topographical patterns and evolution grades observed in affected populations. The purpose of the present study was to evaluate the association between keratoconus evolution grade and topography pattern and the type and design of fitted contact lens. We performed a retrospective analysis of contact lenses fitted in a total of 185 patients with keratoconus (325 eyes). Keratoconus was classified as either grade I, II, III, or IV based on keratometry and cone morphology (nipple, oval, globus, or indeterminate) results. A total of 325 eyes were evaluated in the present study. Of the 62 eyes classified as grade I, 66.1% were fitted with monocurve contact lenses. Of the 162 eyes classified as grade I and II, 51%, 30%, and 19% were fitted with adapted monocurve rigid gas-permeable contact lenses (RGPCL), bicurve lenses, and others lens types, respectively. Bicurve lenses were fitted in 52.1% and 62.2% of eyes classified as grade III and IV, respectively. Of the eyes classified as grade III and IV, monocurve and bicurve RGPCL were fitted in 26% and 55%, respectively. In eyes with oval keratoconus, 45%, 35%, and 20% were fitted with monocurve lenses, bicurve lenses, and other lens types, respectively. In eyes with round cones (nipple morphology), 55%, 30%, and 15% were fitted with bicurve lenses, monocurve lenses, and other lens types, respectively. Monocurve RGPCL were most frequently fitted in patients with mild to moderate keratoconus and oval cones morphology, while bicurve lenses were more frequently fitted in patients with severe and advanced keratoconus. This was probably because bicurve lenses are more appropriate for round cones due to increased corneal asphericity.
Shayani Rad, Maryam; Mohajeri, Seyed Ahmad
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.
Montés-Micó, Robert; Belda-Salmerón, Lurdes; Ferrer-Blasco, Teresa; Albarrán-Diego, César; García-Lázaro, Santiago
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.
Vincent, Stephen J
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.
Sterner, Olof; Aeschlimann, Rudolf; Zürcher, Stefan; Osborn Lorenz, Kathrine; Kakkassery, Joseph; Spencer, Nicholas D; Tosatti, Samuele G P
To characterize the effect of lubricant composition and in vitro ageing on the coefficient of friction (CoF) of a wide range of commercially available soft contact lenses (SCLs). The CoF of SCLs was characterized by means of microtribometry against a mucin-coated glass disk. One reusable (RU) silicone-hydrogel (SiHy) lens, senofilcon A, and two daily disposable (DD) lenses, etafilcon A (hydrogel) and nelfilcon A (hydrogel), were tested under different lubricant solutions, including a tear-like fluid (TLF) containing proteins and lipids. Five RU (balafilcon A [SiHy], comfilcon A [SiHy], etafilcon A [hydrogel], lotrafilcon B [SiHy], senofilcon A [SiHy]) and five DD (delefilcon A [SiHy], etafilcon A [hydrogel; two lens types], narafilcon A [SiHy], nelfilcon A [hydrogel]) lenses were tested before and after exposure to an in vitro ageing process, consisting of continuous immersion and withdrawal from TLF for 18 hours. The CoF in TLF was further compared to previously published data collected in a different lubricant. After in vitro ageing, three RU (balafilcon A, etafilcon A, comfilcon A) and three DD (delefilcon A, etafilcon A, nelfilcon A) lenses displayed a significant increase in CoF (P < 0.05). Lenses that contained poly (vinyl pyrrolidone; PVP) showed unaltered CoF after ageing. An in vitro methodology to simulate in vivo wearing of contact lenses has been proposed. The results suggest that certain lens materials show increased CoF after ageing, with potential clinical implications. The results indicate that the presence of a persistent wetting agent is of advantage to maintain a low CoF after prolonged wearing.
Jung, Hyun Jung; Abou-Jaoude, Michelle; Carbia, Blanca E; Plummer, Caryn; Chauhan, Anuj
Glaucoma is the second major cause of blindness in the world after cataract. Glaucoma management through eye drops that reduce the intraocular pressure (IOP) has major deficiencies including low patient compliance and low bioavailability. Extended wear contact lenses that deliver glaucoma drugs for extended periods could increase patient compliance, while also increasing the bioavailability. To develop extended wear contact lenses that can also provide extended glaucoma therapy, we disperse nanoparticles of PGT (propoxylated glyceryl triacylate) that contain a glaucoma drug timolol. The particles can also be loaded into prefabricated lenses by soaking the lenses in a solution of particles in ethanol. The particle loaded gels can release timolol in phosphate buffered saline (PBS) for about a month at room temperature. The most likely rate controlling mechanism is hydrolysis of the ester bond that links timolol to the PGT matrix, but other mechanisms such as water and drug diffusion, drug dissolution, drug-polymer chain cleavage, time-dependent drug permeability within the polymeric matrix, etc. may also be important. Nanoparticle incorporation in the silicone hydrogels results in reduction in ion and oxygen permeabilities, and an increase in modulus, and the impact on each of these properties is proportional to the particle loading. A gel with 5% particle loading can deliver timolol at therapeutic doses for about a month at room temperature, with a minimal impact on critical lens properties. Preliminary animal studies in Beagle dogs conducted with lenses in which particles are loaded by soaking the lenses in ethanol show a reduction in IOP. Copyright © 2012 Elsevier B.V. All rights reserved.
Boles, S F; Refojo, M F; Leong, F L
After 7 days of continuous wear, Acuvue (Vistakon, Jacksonville, FL, U.S.A.; etafilcon A) lenses were soaked in a Pseudomonas aeruginosa suspension (1.4 x 10(8) cfu/ml). New Acuvue lenses served as controls. A single strain of P aeruginosa harvested from a human corneal ulcer was used throughout the experiment. Lenses were examined by culture and scanning electron microscopy (SEM). We found significantly greater (p less than 0.05) bacterial attachment to new Acuvue lenses [culture, 3.1 x 10(4) (+/- 0.82 x 10(4)) cfu/mm2; SEM, 2.6 x 10(4) (+/- 0.47 x 10(4)) bacteria/mm2] compared with those previously worn [culture, 1.0 x 10(4) (+/- 0.17 x 10(4)) cfu/mm2; SEM, 0.73 x 10(4) (+/- 0.21 x 10(4)) bacteria/mm2]. No statistical difference was found among the individuals. Our findings demonstrate that the biological coating resulting from 1 week of continuous contact lens wear restricts P. aeruginosa attachment to the Acuvue lens when comparing new and used lenses.
Visser, Esther-Simone; Wisse, Robert P L; Soeters, Nienke; Imhof, Saskia M; Van der Lelij, Allegonda
To evaluate the performance of medical contact lenses (CLs) for a wide range of clinical indications. Prospective cross-sectional study. A total of 281 eyes were evaluated in 281 consecutive patients (≥18 years of age; CL use ≥3 months) who visited the contact lens service in a tertiary academic clinic for a scheduled follow-up visit. The main outcome measured were clinical indications for CL wear; CL type; change in corrected distance visual acuity (CDVA) with CL use; CL wearing duration; CL wearing time; subjective performance measured using a visual analog scale (VAS) questionnaire (score range: 0-100); and effectiveness of the lens-selection algorithm. Wearing CLs significantly improved CDVA compared to wearing spectacles (median change: -0.15 logMAR, range: 1.00 to -2.10; P<.001). Daily-wear CLs were worn by 77% of patients for a median of 15h/day (range: 5-18h/day), median 7 days/week (range: 1-7 days/week). High subjective scores were measured, with similar results obtained between the scleral lens and soft lens groups. The medical CL fitting was found to be generally effective (the overall satisfaction rating was ≥70 for 81% of patients). Fitting CLs based on the lens-selection algorithm yielded positive clinical results, including improved visual acuity, satisfactory wearing time, and high overall subjective performance. Moreover, subjective performance was similar between users of scleral lenses and users of soft lenses. These results underscore the importance of prescribing scleral lenses and the need for tertiary eye clinics to offer patients a variety of CL types. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Heynen, Miriam; Luensmann, Doerte; Jones, Lyndon
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
Hui, Alex; Bajgrowicz-Cieslak, Magdalena; Phan, Chau-Minh; Jones, Lyndon
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
Connor, C G; Campbell, J B; Steel, S A; Burke, J H
Some patients can wear contact lenses with a low tear breakup time while others with an identical tear breakup time cannot wear lenses. This suggests the current method of tear film assessment is inadequate at differentiating between these two types of patients. The study attempts to expand our knowledge of the tear film with special attention directed to a critical yet little studied component: mucin. Mucin is vital to maintenance of the tear film and functions as a tear film stabilizer. The condition of the precorneal tear film is a major determinant in the success of contact lens wear. Eighteen subjects free of ocular surface disease who had never worn contact lenses had the goblet cell density of their inferior bulbar conjunctiva determined by impression cytology. The subjects were then fit in a 38 percent water polymacon lens and their goblet cell density determined on a monthly basis for 6 months. Nearly a 2-fold increase in goblet cell density was observed in 88 percent of the subjects over the 6-month period. The first statistically significant increase occurred 5 months after the initiation of lens wear when the goblet cell density rose from 4.19-7.84 percent. We speculate the increase in goblet cells is an adaptive response of the ocular surface to a coated daily wear contact lens.
Hickson-Curran, Sheila; Chalmers, Robin L; Riley, Colleen
To review important aspects of contact lens compliance and to survey contact lens replacement frequency, steps in lens care and hygiene and replacement of the lens storage case via online surveys. Random US samples (n=645 and 787) of frequent replacement contact lens wearers answered questions on contact lens wear in online, sponsor-masked surveys. Wearers of lenses prescribed by their practitioner for 2 weekly replacement reported that they replaced lenses as follows: within 2 weeks 45%, within 3 weeks (minor stretching) 68%, within 4 weeks 89%, ≥8 weeks (extreme stretching) 4%, compared to Monthly wearers who reported: within 4 weeks 37%, within 5 weeks (minor stretching) 57%, ≥8 weeks 23% (≥8 weeks extreme stretching, Chi-square p=0.001). Median frequency for cleaning lens storage case was 2-3 times per week, while 33% reported cleaning monthly or less often. Median lens storage case replacement was every 4-6 months, while 48% reported annual replacement or less often. Most patients cleaned their lens case with hot or cold tap water (72%). These internet surveys revealed significant non-compliance with lens care steps, case hygiene and lens replacement schedule. More than half of the contact lens wearers surveyed were not compliant with their 2-weekly or monthly schedule. Lenses prescribed for longer replacement intervals can lead to more extreme stretching of lens life. To encourage better patient habits, eye care providers should reinforce their recommended frequency of replacement of lenses and storage cases and should reinforce care and hygiene steps at each patient visit. Copyright © 2010. Published by Elsevier Ltd.
Babaei Omali, Negar; Heynen, Miriam; Subbaraman, Lakshman N; Papinski, Dominik; Lakkis, Carol; Smith, Sarah L; Morgan, Philip B; Berntsen, David A; Nichols, Jason J; Jones, Lyndon W
To evaluate the effect of four contemporary lens care solutions on total protein, total lysozyme, and active lysozyme extracted from three contact lens materials. Adapted contact lens wearers were recruited at three sites, and all subjects were randomly assigned to daily wear of either etafilcon A, galyfilcon A, or senofilcon A for 2 weeks. Four lens care solutions (Biotrue, OPTI-FREE PureMoist, RevitaLens OcuTec, and ClearCare) were used by each subject in random order with a new pair of lenses after a washout period between solutions of at least 4 days. After 2 weeks of daily wear, contact lenses were collected for analysis. Proteins were extracted from a subset of contact lenses (n = 568) and total protein, total lysozyme, and lysozyme activity were quantified using a modified Bradford assay, an enzyme-linked immunosorbent assay, and a micrococcal assay, respectively. Higher levels of total protein were extracted from etafilcon A when used with Biotrue compared to other solutions (p = 0.0001). There were higher levels of total lysozyme extracted from galyfilcon A lenses when used with PureMoist than with Biotrue or ClearCare (p < 0.006). Higher total lysozyme was extracted from senofilcon A when used with RevitaLens OcuTec compared to Biotrue (p = 0.002). Lower lysozyme activity was recovered from senofilcon A lenses with RevitaLens OcuTec when compared to all other care solutions (all p < 0.004). When Biotrue, PureMoist, or RevitaLens OcuTec were used, higher total lysozyme was extracted from galyfilcon A compared to senofilcon A (p < 0.01). When RevitaLens OcuTec was used, higher levels of active lysozyme were extracted from galyfilcon A compared to senofilcon A (p = 0.02). The ability of lens care solutions to remove protein from lenses varies depending upon the care solution composition and also the polymeric make-up of the contact lens material.
Lorenz, Kathrine Osborn; Kakkassery, Joseph; Boree, Danielle; Pinto, David
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
de Brabander, John; Chateau, Nicolas; Marin, Gildas; Lopez-Gil, Norberto; Van Der Worp, Eef; Benito, Antonio
Outstanding improvements in vision can theoretically be expected using contact lenses that correct monochromatic aberrations of the eye. Imperfections in such correction inherent to contact lenses are lens flexure, translation, rotation, and tear layer effects. The effects of pupil size and accommodation on ocular aberration may cause further difficulties. The purpose of this study was to evaluate whether nonaxisymmetric soft contact lenses could efficiently compensate for higher-order aberrations induced by keratoconus and to what extent rotation and translation of the lens would degrade this perfect correction. Height topography data of nine moderate to severe keratoconus corneas were obtained using the Maastricht Shape Topographer. Three-dimensional ray tracing was applied to each elevation topography to calculate aberrations in the form of a phase error mapping. The effect of a nonaxisymmetric soft contact lens tailored to the corneal aberrations was simulated by adding an opposite phase error mapping that would theoretically compensate all corneal-induced optical aberrations of the keratoconus eyes. Translation (0.25, 0.5, 0.75, and 1.0 mm) and rotation (2.5 degrees, 5.0 degrees, 7.5 degrees, and 10 degrees ) mismatches were introduced. The modulation transfer function (MTF) of each eye with each displaced correction and with various pupil sizes (3, 5, and 7 mm) was deduced from the residual phase error mapping. A single performance criterion (mtfA) was calculated as the area under the MTF over a limited spatial frequency range (5 to 15 periods per degree). Finally, the ratio (RmtfA) of corrected mtfA over uncorrected mtfA provided an estimate of the global enhancement in contrast sensitivity with the customized lens. The contrast improvement ratios RmtfA with perfectly located lenses were for an average pupil size of 4.5 mm between 6.5 and 200. For small translation errors (0.25 mm), RmtfA ranged between 2 and 7. The largest lens translation tested (1 mm
Malet, Florence; Schnider, Cristina M
This study examines what effects replacement schedule and care regimen have on overall patient satisfaction with daily wear frequent-replacement contact lenses. Over 3000 patients were recruited from 313 ophthalmologic practices in France to participate in a 1-month prospective observational clinical study. Subjects included 2108 experienced and 957 novice users of the predominantly prescribed soft contact lenses and care systems in France. All subjects were required to use ACUVUE 2 (Vistakon, Jacksonville, FL) brand contact lenses, replaced once every 2 weeks, and using COMPLETE brand multipurpose solution (Allergan, Irvine, CA) during the study. Practitioners assessed lens fit, and refractive and ocular physiological status. Subjects were surveyed about various subjective attributes at the baseline examination and at the end of the study. Patient satisfaction with the test lenses and care system was found to be excellent for the majority of patients, as evidenced by high subjective satisfaction ratings and the desire of approximately 9 of 10 subjects to continue using the test products after completing the study. Significant improvements were noted with the test lenses and solution compared to previous lenses and solutions for overall satisfaction and comfort variables. Replacing lenses once every 2 weeks combined with a multipurpose care system incorporating ingredients designed for lens conditioning contributed to significant improvements in lens wearing comfort. Thus, lens replacement frequency and lens-and-solution compatibility should be considered in addition to lens material and design when prescribing contact lenses for new or existing wearers.
Heynen, Miriam; Liu, Lina; Sheardown, Heather; Jones, Lyndon
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
Pearson, Richard M
It is generally believed that the clinical performance of the original Czechoslovakian hydrogel contact lenses was poor but historical reviews provide very little explanation regarding their failings. There is a lack of information in the literature about their dimensions and, in particular, thickness, which is essential for the calculation of oxygen transmissibility. Until now no measurements on Czechoslovakian lenses have been reported. A literature search on Czechoslovakian lenses was made that spanned the first decade of their use and included peer-reviewed journals, non-refereed publications and a number of archived documents. In addition, the water content and dimensions of five Geltakt and four Spofa lenses were measured. Lens packaging, lens lifetime, hygienic care, visual acuity, nominal lens dimensions, flexure, failure to correct astigmatism, corneal oedema, oxygen transmissibility, complications and wearing time are reviewed. Measurements on Czechoslovakian lenses indicate that the total diameter was similar to that of the cornea, the back optic zone radius was steep and the centre thickness was large. Problems associated with the Czechoslovakian lenses included packaging and an initial failure to require daily disinfection. Few complications of lens wear were reported, probably due to the comparatively small number of patients fitted and the limited wearing time that they achieved. Delayed disclosure of lens dimensions handicapped the development of a fitting technique. An acceptable visual acuity was attained in selected cases, while reduced acuity may sometimes have been due to uncorrected astigmatism or to poor lens quality. The most serious disadvantage was the very low oxygen transmissibility that could result in marked corneal oedema.
Keir, Nancy; Luensmann, Doerte; Woods, Craig A; Bergenske, Peter; Fahmy, Mary; Fonn, Desmond
To explore the effect of masking on subjective responses when wearing daily disposable (DD) contact lenses. In an adaptation phase, habitual wearers of Manufacturer-A (MFA) (n = 43) and Manufacturer-B (MFB) (n = 53) wore MFA-brand 1 or MFB-brand 1 DDs, respectively, for 30 days, open-label. Subjects were then randomly assigned to one of two experiments. Each experiment included two, 3-day crossover phases. An enhanced version of MFA and MFB lenses (MFA-brand 2 and MFB-brand 2) were worn contralaterally to evaluate potential differences in masking result between manufacturers. Experiment 1: subjects were fully masked to lens and packaging (FM) then unmasked (UM). Experiment 2: subjects were FM then partially masked using an over-label (PM). Comfort ratings (0-100) were recorded for each lens daily and preference between lenses was recorded on day 3 for each crossover phase. The mean difference between 0-100 ratings or preference when FM or PM versus UM for the same lens was considered a measurement of the effect associated with masking. The purpose of the study was withheld from subjects to minimize bias. The effect associated with masking for habitual wearers of MFA and MFB lenses was less than 1 out of 100 (0 ± 2.5) in both experiments. Fifty-eight subjects (60%) expressed no preference when FM. This decreased to 29 (30%) when UM or PM (proportion test, p < 0.001). Approximately half the subjects had a change in lens preference when they were UM or PM, primarily in favor of their habitual lens manufacturer. Masking did not have a measurable impact on 0-100 ratings with the DD lenses used in this study but did have an impact on lens preference. Subjects were more likely to express a preference when they handled the lenses and were exposed to the lens packaging and, in some cases, able to read the lens brand and lens manufacturer.
Jiang, Ying; Jacobs, Michael; Bajaksouzian, Saralee; Foster, Altreisha N; Debanne, Sara M; Bielefeld, Roger; Garvey, Matt; Raghupathy, Sangeetha; Kern, Jami; Szczotka-Flynn, Loretta B
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.
Findl, O; Menapace, R; Georgopoulos, M; Kiss, B; Petternel, V; Rainer, G
To characterize the morphology, size, and change in size of the contact zone of piggyback intraocular lenses (IOLs) of different materials and optic designs. Department of Ophthalmology, Vienna General Hospital, Vienna, Austria. In a prospective study, 9 eyes of 7 patients received piggyback IOLs of the following materials: poly(methyl methacrylate) (PMMA), acrylic, hydrogel, and silicone. The contact zone between the anterior and posterior IOLs was photodocumented from 1 day to 1 year after surgery using specular microscopy. The contact zone area was measured. A contact zone was present with all IOL materials studied. The area of contact, however, differed significantly. With PMMA IOLs, the contact zone was small and surrounded by Newton rings, indicating the tiny gap between the IOLs. With IOLs of soft material, such as silicone and hydrogel, it was larger than with PMMA IOLs and had a slightly irregular shape. With foldable acrylic IOLs, it was regular, round, and slightly larger than with the soft materials. The contact area enlarged primarily during the first 3 months after surgery. After 1 year, 2 eyes with acrylic piggyback IOLs had a membrane formation around the contact zone and 2 eyes developed Elschnig pearls between the IOLs. In piggyback IOL eyes, the shape and size of the contact zone were strongly dependent on the IOL material and optic design. Contact area enlargement seemed to be induced by capsule shrinkage. Fibrous membrane formation around the contact zone and Elschnig pearl formation between the piggyback IOLs were long-term complications of this technique.
de Jong, Bram; van der Meulen, Ivanka J E; van Vliet, Johannes M J; Lapid-Gortzak, Ruth; Nieuwendaal, Carla P; van den Berg, Thomas J T P
To study the effects of corneal scars and the treatment of these scars with rigid gas-permeable (RGP) contact lenses on quality of vision including straylight. Visual effects were related to scar characteristics such as size and grade. Straylight and best-corrected visual acuity were measured in 23 patients with corneal scars during and after RGP contact lens wear. Contralateral eyes were used as controls, and age-normal values in case of bilateral scars. Straylight measurements were performed using the compensation comparison method of the Oculus C-Quant instrument. Scarred eye straylight values were 1.53 log(s) without contact lens and 1.60 log(s) with contact lens (P=0.043). Healthy eyes without contact lens had a mean straylight value of 1.13 log(s), corresponding to age-normal values. Contact lens wear increased straylight in healthy eyes to 1.26 log(s) (P<0.001). Visual acuity improved from 0.66 logarithm of minimal angle of resolution (logMAR) to 0.19 logMAR with contact lens wear in eyes with a corneal scar (P<0.001). Corneal scars can have a strong effect on quality of vision by diminishing visual acuity and increasing straylight. The increase in straylight from corneal scars on its own can lead to a serious visual handicap. Contact lens treatment did not improve straylight, but showed a slight worsening. As the recovery of visual acuity with contact lens wear far exceeded straylight increase, contact lenses remain a clinically useful treatment option in most patients with corneal scars.
Fonn, D; Gauthier, C A; Pritchard, N
Patient preferences and ocular responses were compared between rigid and soft contact lenses by randomly fitting 32 neophyte subjects with a rigid lens in 1 eye and a soft lens in the contralateral eye. Twenty-seven of 32 subjects completed the 3-month study and 16 subjects were willing to continue for an additional 3-month extension. Subjects preferred the comfort and handling of the soft lens but preferred the vision provided by the rigid lens and initially its ease of maintenance. There was also a marked preference for the soft lens when all aspects of lens wear were compared. Objectively, the rigid lenses were responsible for more ocular changes than the soft lenses. Palpebral aperture sizes of the rigid gas permeable (RGP) wearing eyes decreased significantly (0.5 mm; p < 0.05) compared to the soft lens wearing eyes. The incidence of corneal staining was significantly greater in the rigid lens wearing eye (50% RGP vs. 22% soft) but limbal injection was greater in the soft lens wearing eye (18% soft vs. 6% RGP). Refractive sphere, cylinder, and corneal astigmatism decreased in the rigid lens wearing eye after 3 months. This daily wear clinical trial has shown a marked subjective preference for wearing soft lenses with fewer short-term ocular effects.
Galas, Stephen; Copper, Lenora L
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
Galas, Stephen; Copper, Lenora L
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 (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). The pigment colorant and PVP embedded in the contact lens during autoclaving were not found to influence
García-Millán, Eva; Quintáns-Carballo, Mónica; Otero-Espinar, Francisco Javier
Drug nanosuspensions (NSs) show a significant potential to improve loading and release properties of the poorly water soluble drug triamcinolone acetonide (TA) from poly(hydroxyethyl methacrylate) (pHEMA) soft contact lenses. In this work, TA NSs were developed by a controlled precipitation method using a fractional factorial Plackett-Burmann design. Poloxamer 407 (PL) and polyvinyl alcohol (PVA) as stabilizing agents were selected. NSs were characterized in terms of their drug content, particle size and morphology. Results indicate that all studied factors, except homogenization speed and sonication, have significant influence on the drug incorporation yield into NSs. Drug nanoparticles showed an interesting size that may be suitable for their incorporation into topical ocular drug delivery systems, as hydrogels. pHEMA hydrogels and daily-wear Hilafilcon B commercial contact lenses (SCLs) were employed to study TA loading capacity and drug release properties using NSs as loading system. Hydrogels have been synthesised by copolymerization of 2-hydroxyethyl methacrylate (HEMA) with methacrylic acid (MA) in accordance with a previous work (García-Millán et al., 2015). Both synthesised hydrogels and SCLs were characterized in terms of their mechanical and physical properties and TA loading and release properties. Selected TA NS was further characterized by studying its physical-chemical stability during the loading process. Results show that the use of TA NSs as loading medium significantly increases drug loading capacity and release of soft contact lenses in comparison with drug saturated solution. Synthesised pHEMA hydrogels and SCLs lenses have good properties as ophthalmic drug delivery systems, but SCLs load higher quantities of drug and release TA in shorter time periods than synthesised pHEMA hydrogel. Copyright © 2017 Elsevier B.V. All rights reserved.
Ascaso, Francisco J; Huerva, Valentín
: 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.
Berntsen, David A.; Merchea, Mohinder M.; Richdale, Kathryn; Mack, Carla J.; Barr, Joseph T.
Purpose To determine the on-eye effect of spherical and toric contact lens design on higher-order aberrations (HOA). Methods Thirty eyes (15 subjects) entered a masked, randomized, cross-over study. Each eye was fitted with the spherical and toric lens of the following brands in random order: Acuvue Advance, Biomedics 55, Frequency 55, and SofLens 66. HOAs were measured using the Zywave II Aberrometer over a 6-mm aperture up to fifth order. A linear model accounting for the fixed effect of lens type and random effects of subject and eye was created. Paired t-tests were completed between lens brands within the spherical and toric lenses and between the spherical and toric lens within each brand. Best-corrected visual acuity (VA) was measured and compared. Results No clinically meaningful differences in total HOAs were found between brands or between the spherical and toric lens within a brand. Positive spherical aberration (SA) was reduced by all spherical and toric lenses compared to wearing no lens by 0.07 to 0.23 μm (p<0.0001). Frequency toric induced the greatest change in SA. The thin-zone design lens (Acuvue Advance for Astigmatism) had a statistically different amount of vertical coma (−0.04 μm) than the three prism-balast toric lenses (0.11 to 0.23 μm; p<0.0001). SofLens toric had the greatest amount of vertical coma, but better VA than Acuvue Advance for Astigmatism and Frequency toric. With the exception of Acuvue Advance for Astigmatism, toric lenses had greater absolute magnitude of vertical coma than their sphere counterparts (all p<0.002). No other significant HOA differences were observed. Conclusions Toric contact lenses with prism-ballast designs demonstrated more vertical coma, but better VA. Positive SA was reduced by spherical and toric contact lenses. The visual quality effect of lens design and material on induced HOAs warrants further investigation. PMID:19156015
González-Méijome, José M; Lira, Madalena; López-Alemany, Antonio; Almeida, José B; Parafita, Manuel A; Refojo, Miguel F
The purpose of the present study was to measure equilibrium water content (EWC) and refractive index of conventional and silicone hydrogel soft contact lenses (SCL) using a hand refractometer and an automated refractometer. Sixteen SCL were used in this study including 12 conventional SCL not containing siloxane moieties (equilibrium water content (EWC) range: 38.6-74%) and the four silicone hydrogel based contact lenses currently available (WC range: 24-47%). Two experienced observers performed the measurements in a randomised order being masked by a third party during the three sessions at which the measurements were collected. The Atago N-2E hand refractometer and the CLR 12-70 digital refractometer were used. Data were analysed separately for conventional and silicone hydrogel materials. Measured EWC and refractive index correlate better when measured with the instruments used in this study (r(2) = 0.979, p < 0.001) than the nominal parameters (r(2) = 0.666, p < 0.001). The linear relationship that correlates nominal and measured EWC shows higher spread of data when all lenses are analysed together (r(2) = 0.840) than when conventional hydrogel (r(2) = 0.953) and silicone hydrogel contact lenses (r(2) = 0.967) are analysed separately. Regarding refractive index, the relationship between nominal and measured values when all the lenses are considered together (r(2) = 0.794) becomes weaker when conventional hydrogel are considered separately (r(2) = 0.688), while a stronger relationship is observed for silicone hydrogel lenses (r(2) = 0.939). Hence, hand refractometry overestimates the EWC of silicone hydrogels, while automated refractive index measurements are more accurate in silicone hydrogels than in conventional hydrogels. New relationships are presented that correlate nominal and measured values of EWC and refractive index for the silicone containing hydrogels. The linear relationships derived fit well to the data. Hand refractometry overestimates the EWC of
Maulvi, Furqan A; Lakdawala, Dhara H; Shaikh, Anjum A; Desai, Ankita R; Choksi, Harsh H; Vaidya, Rutvi J; Ranch, Ketan M; Koli, Akshay R; Vyas, Bhavin A; Shah, Dinesh O
Glaucoma is commonly treated using eye drops, which is highly inefficient due to rapid clearance (low residence time) from ocular surface. Contact lenses are ideally suited for controlled drug delivery to cornea, but incorporation of any drug loaded particulate system (formulation) affect the optical and physical property of contact lenses. The objective of the present work was to implant timolol maleate (TM) loaded ethyl cellulose nanoparticle-laden ring in hydrogel contact lenses that could provide controlled drug delivery at therapeutic rates without compromising critical lens properties. TM-implant lenses were developed, by dispersing TM encapsulated ethyl cellulose nanoparticles in acrylate hydrogel (fabricated as ring implant) and implanted the same in hydrogel contact lenses (sandwich system). The TM-ethyl cellulose nanoparticles were prepared by double emulsion method at different ratios of TM to ethyl cellulose. The X-ray diffraction studies revealed the transformation of TM to amorphous state. In vitro release kinetic data showed sustained drug release within the therapeutic window for 168h (NP 1:3 batch) with 150μg loading. Cytotoxicity and ocular irritation study demonstrated the safety of TM-implant contact lenses. In vivo pharmacokinetic studies in rabbit tear fluid showed significant increase in mean residence time (MRT) and area under curve (AUC), with TM-implant contact lenses in comparison to eye drop therapy. In vivo pharmacodynamic data in rabbit model showed sustained reduction in intra ocular pressure for 192h. The study demonstrated the promising potential of implantation technology to treat glaucoma using contact lenses, and could serve as a platform for other ocular diseases. Copyright © 2016 Elsevier B.V. All rights reserved.
Lin, David Pei-Cheng; Chang, Han-Hsin; Yang, Li-Chien; Huang, Tzu-Ping; Liu, Hsiang-Jui; Chang, Lin-Song; Lin, Chien-Hsun
Purpose Weekly disposable soft contact lenses have been widely used recently, but their shield effects against ultraviolet (UV) irradiation remain to be evaluated. This study investigated the bioprotective effects of several weekly soft contact lenses against UVB irradiation on the corneal surface in a mouse model. Methods Fifty ICR mice were randomly divided into five groups: (1) blank control, (2) exposed to UVB without contact lens protection, (3) exposed to UVB and protected with Vifilcon A contact lenses, (4) exposed to UVB and protected with Etafilcon A contact lenses, and (5) exposed to UVB and protected with HEMA+MA contact lenses. The exposure to UVB irradiation was performed at 0.72 J/cm2/day after anesthesia for a 7-day period, followed by cornea surface assessment for smoothness, opacity, and grading of lissamine green staining. Tissue sections were prepared for hematoxylin and eosin staining and immunohistochemical detection by using antibodies against myeloperoxidase, cytokeratin-5, P63, Ki-67, nuclear factor-kappa B (p65), cyclooxygenase-2, Fas L, and Fas. Results The results showed impaired corneal surface with myeloperoxidase+ polymorphonuclear leukocyte infiltration into the stroma after UVB exposure, in contrast to the intact status of the blank controls. The corneas with Etafilcon A and HEMA+MA contact lenses maintained more cells positive for cytokeratin-5, P63, and Ki-67 compared to those with Vifilcon A or without contact lens protection. Furthermore, less proinflammatory factors, including nuclear factor-kappa (p65), cyclooxygenase-2, Fas L, and Fas, were induced in the corneas protected by Etafilcon A and HEMA+MA. Conclusions This study demonstrated various protective effects of weekly disposable contact lenses against UVB irradiation. The mouse model used in the present study may be used extensively for in vivo assessment of UV shield efficacy. PMID:23734085
Filipecka, Katarzyna; Miedziński, Rafał; Sitarz, Maciej; Filipecki, Jacek; Makowska-Janusik, Małgorzata
The Raman, MIR and UV-vis spectroscopy have been used to characterize Omafilcon A material constructing the one of the Proclear family contact lenses. The Omafilcon A is hydrogel material composed of 2-hydroxyethyl methacrylate (HEMA) and 2-methacryloyloxyethyl phosphorylcholine (PC) polymers crosslinked with ethyleneglycol dimethacrylate (EGDMA). Vibrational and electronic properties of the Omafilcon A material were also investigated by quantum chemical calculations. Experimentally obtained Raman, MIR and optical spectra were compared to the theoretical ones calculated applying RHF and DFT methodology. The quantum chemical calculations were performed for isolated monomers of lenses compounds as well as for their dimers and trimers to elucidate the effect of Omafilcon A polymerization and the role of an individual components.
Tam, Ngai Keung; Pitt, William G; Perez, Krystian X; Handly, Erika; Glenn, Andrew A; Hickey, John W; Larsen, Brian G
The sorption and desorption of radiolabeled dipalmitoylphosphatidylcholine (DPPC) and cholesterol (CH) were measured on 5 types of commercial contact lenses. The lenses were soaked in vitro in an artificial tear fluid for 16h. The effects of borate buffered saline and two commercial multi-purpose lens-care solutions (MPSs) on reducing the lipid (DPPC and CH) sorption and increasing the lipid removal were examined. The results showed that silicone hydrogel (SiHy) lenses accumulated the most lipids, sorbing over an order of magnitude more than polymacon, a conventional hydrogel lens. Pre-soaking the SiHy lenses for 16h in MPSs reduced the DPPC sorption by up to 13% and the CH sorption by up to 11%, compared to controls that were not pre-soaked. However neither these reductions nor those on polymacon were statistically significant (p>0.05). In sorption experiments without presoaking, subsequent exposure to the MPSs removed some DPPC from the lenses (0-3.1% for SiHy lenses and 14-55% for polymacon), but CH removal was 0.0-0.8% for SiHy lenses and 0.6-28% for polymacon lenses. Some of these removals were statistically significant (p<0.05). Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Filipecki, Jacek; Kotynia, Katarzyna; Filipecka, Katarzyna
Hydrogel and silicone-hydrogel polymeric materials are widely used in ophthalmology for the manufacture of contact lenses. An important aspect is the investigation of the structure of these materials. This study has been conducted in order to compare the degree of disorder and presence of free volumes in the internal structure of the polymeric soft contact lenses Omafilcon A (hydrogel) and Comfilcon A (silicone-hydrogel). Differences in the occurrence of trapping centers for positrons and free volumes between the types of investigated contact lenses have been demonstrated. Two types of polymeric contact lenses were used as materials: Omafilcon A (hydrogel) and Comfilcon A (silicone-hydrogel). The study was performed using positron annihilation lifetime spectroscopy (PALS). When the results of the measurements has been obtained, a graphical curve has created to describe the relationship of the number of annihilation acts in time. Significant changes were observed between the contact lenses investigated in positron trapping in macropores (based on a two-state model) and the presence of free volumes (based on the Tao-Eldrup model). The use of the positron annihilation two-state model made it possible to demonstrate that a higher positron trapping rate in macropores occurs in the silicone-hydrogel contact lens. Additionally, calculations using the Tao-Eldrup model show the existence of free volumes in both types of materials. The size and fraction of free volumes is much larger in the silicone-hydrogel contact lens.
Walline, Jeffrey J; Gaume Giannoni, Amber; Sinnott, Loraine T; Chandler, Moriah A; Huang, Juan; Mutti, Donald O; Jones-Jordan, Lisa A; Berntsen, David A
The Bifocal Lenses In Nearsighted Kids (BLINK) study is the first soft multifocal contact lens myopia control study to compare add powers and measure peripheral refractive error in the vertical meridian, so it will provide important information about the potential mechanism of myopia control. The BLINK study is a National Eye Institute-sponsored, double-masked, randomized clinical trial to investigate the effects of soft multifocal contact lenses on myopia progression. This article describes the subjects' baseline characteristics and study methods. Subjects were 7 to 11 years old, had -0.75 to -5.00 spherical component and less than 1.00 diopter (D) astigmatism, and had 20/25 or better logMAR distance visual acuity with manifest refraction in each eye and with +2.50-D add soft bifocal contact lenses on both eyes. Children were randomly assigned to wear Biofinity single-vision, Biofinity Multifocal "D" with a +1.50-D add power, or Biofinity Multifocal "D" with a +2.50-D add power contact lenses. We examined 443 subjects at the baseline visits, and 294 (66.4%) subjects were enrolled. Of the enrolled subjects, 177 (60.2%) were female, and 200 (68%) were white. The mean (± SD) age was 10.3 ± 1.2 years, and 117 (39.8%) of the eligible subjects were younger than 10 years. The mean spherical equivalent refractive error, measured by cycloplegic autorefraction was -2.39 ± 1.00 D. The best-corrected binocular logMAR visual acuity with glasses was +0.01 ± 0.06 (20/21) at distance and -0.03 ± 0.08 (20/18) at near. The BLINK study subjects are similar to patients who would routinely be eligible for myopia control in practice, so the results will provide clinical information about soft bifocal contact lens myopia control as well as information about the mechanism of the treatment effect, if one occurs.
Butt, Thomas; Crossland, Michael D; West, Peter; Orr, Shepley W; Rubin, Gary S
The National Institute for Health and Care Excellence (NICE) has recommended the use of ranibizumab for neovascular age-related macular degeneration (AMD) and for diabetic macular oedema (DMO) as part of its health technology appraisal process. In the economic evaluations of both interventions, utility values were derived from members of the general public wearing contact lenses with a central opacity that was meant to simulate the blind spot experienced by many patients with advanced retinal disease. This paper tests the validity of the contact lens simulation, and finding it to be invalid, explores the impact on prior economic evaluations. Visual acuity, contrast sensitivity and visual fields were assessed with and without simulation lenses in five healthy subjects with normal vision. We identified important differences between the contact lens simulation and vision loss experienced by patients with AMD. The contact lens simulator did not cause the central scotoma which is characteristic of late-stage AMD and which leads to severe difficulty with everyday activities such as reading or recognising faces and objects. The contact lens instead caused a reduction in retinal illumination experienced by the subjects as a general dimming across the retina. A contact lens with a central opacity does not simulate a central scotoma. The clinical differences between simulated and actual AMD suggest there has been an underestimation of the severity of AMD health states. This brings into question the validity of the economic evaluations of treatments for AMD and DMO used by NICE. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
Jones, Lyndon; Powell, Charles H
Contact lens solutions are highly complex mixtures of biocides (preservatives), surfactants, and other agents designed to disinfect, clean, and wet contact lenses. The commercialization of silicone hydrogel (SiHy) lenses has resulted in unique challenges to the manufacturers of contact lens solutions, because the properties of these materials differ markedly from those seen previously with poly-hydroxyethyl methacrylate-based hydrogels. Historically, hydrogel lens uptake and release of low-molecular weight preservatives such as chlorhexidine and thimerosal were known to result in allergic reactions, resulting in corneal irritation, stinging, conjunctival hyperemia, development of corneal infiltrates, palpebral lid changes, and corneal staining. However, little is known about the interaction of modern care systems with modern soft lens materials. Factors to be considered when evaluating the uptake and release of care components include the water content, charge, relative hydrophobicity, surface treatment, and porosity of the lens material, in conjunction with the concentration, charge/molecule, ionicity in the product matrix, molecular weight, and hydrophobicity of the care component in question. These factors control the sorption of the solution components by lenses, resulting in a variety of differences in the amount of the component taken up into the lens material and the amount and rate of subsequent release onto the ocular surface. Because both natural (ocular) and environmental biota become part of the solution-lens system during regimen use of any lens care product, these extraneously introduced substances should also be considered regarding their potential for uptake and either subsequent release onto the ocular surface or functioning as a scaffold for the adhesion of microbes. This article will review current knowledge concerning these interactions and investigate what clinically observable complications may arise from these interactions. It also reviews
Schürer, M; Walter, A; Brünner, H; Langenbucher, A
Colored transparent filters cause a change in color perception and have an impact on the perceptible amount of different colors and especially on the ability to discriminate between them. Yellow or orange tinted contact lenses worn to enhance contrast vision by reducing or blocking short wavelengths also have an effect on color perception. The impact of the yellow and orange tinted contact lenses Wöhlk SPORT CONTRAST on color discrimination was investigated with the Erlangen colour measurement system in a study with 14 and 16 subjects, respectively. In relation to a yellow reference color located at u' = 0.2487/v' = 0.5433, measurements of color discrimination thresholds were taken in up to 6 different color coordinate axes. Based on these thresholds, color discrimination ellipses were calculated. These results are given in the Derrington, Krauskopf and Lennie (DKL) color system. Both contact lenses caused a shift of the reference color towards higher saturated colors. Color discrimination ability with the yellow and orange colored lenses was significantly enhanced along the blue-yellow axis in comparison to the reference measurements without a tinted filter. Along the red-green axis only the orange lens caused a significant reduction of color discrimination threshold distance to the reference color. Yellow and orange tinted contact lenses enhance the ability of color discrimination. If the transmission spectra and the induced changes are taken into account, these results can also be applied to other filter media, such as blue filter intraocular lenses.
Rotman, S; Sandovsky-Losica, Hana; Sionov, E; Segal, Esther
The objective of the study was to evaluate the effect of supplementation of a chitin soluble extract (CSE) to clinically used commercial contact lenses' cleaning/preservation solutions on adherence of Aspergillus niger and Candida albicans to contact lenses. CSE (25 mg ml-1) was added to Solocare or Oxysept. Adherence of A. niger or C. albicans to contact lenses was assessed by exposing lenses to fungi in test solutions and enumeration of fungal colony forming unit. The study included three parts: (i) the disinfecting and adherence-inhibiting effect of Solocare and Oxysept: (ii) the adherence-inhibiting effect of CSE; (iii) the effect of Solocare + CSE or Oxysept + CSE on the fungal adherence to contact lenses. The experiments showed that: (i) Solocare had a significant disinfecting effect on A. niger and C. albicans while that of Oxysept was only minimal. (ii) Neither Solocare nor Oxysept had an inhibitory effect on the fungal adherence. (iii) CSE inhibited significantly the adherence of A. niger and C. albicans. (iv) Addition of CSE to Solocare or Oxysept resulted in almost complete inhibition of adherence Supplementing CSE to lenses' maintenance solutions increases their antifungal potential by adding anti-adherence activity to the disinfecting effect of these solutions, bearing the potential to serve as a prophylactic means.
Maldonado-Codina, Carole; Morgan, Philip B
This study investigated the water contact angles of five commercially available silicone hydrogel contact lenses (Acuvue Advance, Acuvue Oasys, Focus Night & Day, O2 Optix, and PureVision) using sessile drop and captive bubble techniques. The only lens type that showed a significant difference in water contact angle when measured by sessile drop direct from the blister compared with after 48 h of soaking/washing in saline was the Acuvue Advance lens (from 66 degrees to 96 degrees, respectively) (p=0.0002), presumably because of surface active agents within the blister solution. The water contact angle data split the lenses into two distinct groups (p
Hydrogels were the first biomaterials designed for clinical use. Their discovery and applications as soft contact lenses and implants are presented. This early hydrogel research served as a foundation for the expansion of biomedical polymers research into new directions: design of stimuli sensitive hydrogels that abruptly change their properties upon application of an external stimulus (pH, temperature, solvent, electrical field, biorecognition) and hydrogels as carriers for the delivery of drugs, peptides, and proteins. Finally, pathways to self-assembly of block and graft copolymers into hydrogels of precise 3D structures are introduced. PMID:19918374
González-Méijome, J M; López-Alemany, A; Almeida, J B; Parafita, M A
To evaluate the qualitative and quantitative topographic changes in the surface of worn contact lenses (CLs) of different materials using atomic force microscopy (AFM). The topography of five different CL materials was evaluated with AFM over a surface of 25 microm(2) according to previously published experimental setup. Average roughness (R(a)) and root mean square (Rms) values were obtained for unworn and worn samples. The R(a) value increased for balafilcon A (11.62-13.68 nm for unworn and worn samples, respectively), lotrafilcon A (3.67-15.01 nm for unworn and worn samples, respectively), lotrafilcon B (4.08-8.42 nm for unworn and worn samples, respectively), galyfilcon A (2.81-14.6 nm for unworn and worn samples, respectively), and comfilcon A (2.87-4.63 nm for unworn and worn samples, respectively). Differences were statistically significant for all lenses except Rms and R(a) for comfilcon A, and R(a) parameter for balafilcon A (p > 0.05). The least relative increase was observed for some balafilcon A samples and for some of these samples the roughness decreased after the lenses had been worn. The changes in surface roughness between unworn and worn lenses are different for different silicone-hydrogel materials. Overall all CLs increased the degree of surface roughness after being worn, even for very short periods of time. However, for samples of balafilcon A, roughness increases at a lower extent or even can decrease as compared to unworn samples of the same material due to filling of the macropores. (c) 2008 Wiley Periodicals, Inc.
Szczotka-Flynn, Loretta B.; Pearlman, Eric; Ghannoum, Mahmoud
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
Hiraoka, Takahiro; Ishii, Yuko; Okamoto, Fumiki; Oshika, Tetsuro
To investigate the influence of cosmetically tinted soft contact lenses on ocular higher-order aberrations and visual performance, and to analyze the relationship between these parameters after the lens wear. In 44 eyes of 22 subjects, visual acuity, contrast sensitivity under photopic and mesopic conditions, and ocular higher-order aberrations were evaluated before and after wearing the tinted soft contact lenses (1-day Acuvue Colours; Vistakon, Jacksonville, FL). Contrast sensitivity under a photopic condition was determined at 3, 6, 12, and 18 cycles per degree, and the area under the log contrast sensitivity function (AULCSF) was calculated. Mesopic contrast sensitivity with and without glare was assessed. Ocular higher-order aberrations for a 4-mm pupil were measured, and coma-like, spherical-like, and total higher-order aberrations were determined. The tinted contact lens wearing resulted in significant decreases in log contrast sensitivity at all spatial frequencies (P < 0.05) and AULCSF (P < 0.0001), although 100% contrast visual acuity did not change. Log mesopic contrast sensitivity with and without glare was also reduced significantly by the lens wear (P < 0.0001). The contact lens wear significantly increased coma-like, spherical-like, and total higher-order aberrations (P < 0.0001). The induced changes in higher-order aberrations were analyzed in relation to the changes in contrast sensitivity function. Although the changes in coma-like and spherical-like aberrations did not correlate significantly with those in AULCSF (P > 0.05), the changes in total higher-order aberrations showed a significant correlation with those in AULCSF (P < 0.05). On the other hand, there was no significant relationship between the changes in higher-order aberrations and the changes in log mesopic contrast sensitivity with and without glare (P > 0.05). Cosmetically tinted contact lenses increase ocular higher-order aberrations and worsen contrast sensitivity under both
Lee, Sangkyu; Jo, Insu; Kang, Sangmin; Jang, Bongchul; Moon, Joonhee; Park, Jong Bo; Lee, Soochang; Rho, Sichul; Kim, Youngsoo; Hong, Byung Hee
Recently, smart contact lenses with electronic circuits have been proposed for various sensor and display applications where the use of flexible and biologically stable electrode materials is essential. Graphene is an atomically thin carbon material with a two-dimensional hexagonal lattice that shows outstanding electrical and mechanical properties as well as excellent biocompatibility. In addition, graphene is capable of protecting eyes from electromagnectic (EM) waves that may cause eye diseases such as cataracts. Here, we report a graphene-based highly conducting contact lens platform that reduces the exposure to EM waves and dehydration. The sheet resistance of the graphene on the contact lens is as low as 593 Ω/sq (±9.3%), which persists in an wet environment. The EM wave shielding function of the graphene-coated contact lens was tested on egg whites exposed to strong EM waves inside a microwave oven. The results show that the EM energy is absorbed by graphene and dissipated in the form of thermal radiation so that the damage on the egg whites can be minimized. We also demonstrated the enhanced dehydration protection effect of the graphene-coated lens by monitoring the change in water evaporation rate from the vial capped with the contact lens. Thus, we believe that the graphene-coated contact lens would provide a healthcare and bionic platform for wearable technologies in the future.
White, Charles J; McBride, Matthew K; Pate, Kayla M; Tieppo, Arianna; Byrne, Mark E
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.
Weeks, Andrea; Luensmann, Doerte; Boone, Adrienne; Jones, Lyndon; Sheardown, Heather
Model silicone hydrogel contact lenses, comprised of N,N-dimethylacrylamide and methacryloxypropyltris (trimethylsiloxy) silane, were fabricated and hyaluronic acid (HA) was incorporated as an internal wetting agent using a dendrimer-based method. HA and dendrimers were loaded into the silicone hydrogels and cross-linked using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide chemistry. The presence and location of HA in the hydrogels was confirmed using X-ray photoelectron spectroscopy and confocal laser scanning microscopy, respectively. The effects of the presence of HA on the silicone hydrogels on hydrophilicity, swelling behavior, transparency, and lysozyme sorption and denaturation were evaluated. The results showed that HA increased the hydrophilicity and the equilibrium water content of the hydrogels without affecting transparency. HA also significantly decreased the amount of lysozyme sorption (p < 0.002). HA had no effect on lysozyme denaturation in hydrogels containing 0% and 1.7% methacrylic acid (MAA) (by weight) but when the amount of MAA was increased to 5%, the level of lysozyme denaturation was significantly lower compared to control materials. These results suggest that HA has great potential to be used as a wetting agent in silicone hydrogel contact lenses to improve wettability and to decrease lysozyme sorption and denaturation.
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Montalt, Juan Carlos; Porcar, Esteban; España-Gregori, Enrique; Peris-Martínez, Cristina
To assess the visual quality achieved by fitting corneo-scleral contact lenses (CScL) for keratoconus management. Thirty patients with keratoconus presented to have CScL fitted because of the unsatisfactory visual quality they experienced with their contact lenses or spectacles. The eye examination included visual acuity assessment, anterior eye biomicroscopy, ocular fundus examination, corneal topographic analysis, endothelial-cell count, contrast sensitivity and aberrometry. The fitting process was performed using a diagnostic trial set. Subjective visual quality and comfort, and contact lens wear time were also reported. Patients were monitored for one year. Three patients discontinued CScL wear before one year. Therefore, 27 eyes of 27 patients (19 male and 8 female) participated in this study. The mean age was 36.1 ± 13.1 (mean ± SD) years. Statistically significant differences were found in logMAR visual acuity between the best spectacle-corrected vision and after CScL fitting (mean ± SD, 0.23 ± 0.30 and 0.00 ± 0.14, respectively; p < 0.001). The total high-order aberrations decreased significantly (55%), and the spatial frequencies of contrast sensitivity all improved to normal range values of the population. Furthermore, high subjective visual quality and comfort ratings, and prolonged usage times (mean ± SD, 13.44 ± 2.38 h a day) were reported. No adverse ocular effects or clinically relevant changes in corneal parameters, visual quality, comfort or usage time were found one year after wearing CScL. This CScL seems to be safe and healthy, providing optimal visual quality, comfort and prolonged usage times in patients with keratoconus. Copyright © 2018 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Pinto-Fraga, José; Blázquez Arauzo, Francisco; Urbano Rodríguez, Rubén; González-García, María J
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.
Mohammadi, Saman; Jones, Lyndon; Gorbet, Maud
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
Bertozzi, Carolyn R.
Nature has evolved complex and elegant materials well suited to fulfill a myriad of functions. Lubricants, structural scaffolds and protective sheaths can all be found in nature, and these provide a rich source of inspiration for the rational design of materials for biomedical applications. Many biological materials are based in some fashion on hydrogels, the crosslinked polymers that absorb and hold water. Biological hydrogels contribute to processes as diverse as mineral nucleation during bone growth and protection and hydration of the cell surface. The carbohydrate layer that coats all living cells, often referred to as the glycocalyx, has hydrogel-like properties that keep cell surfaces well hydrated, segregated from neighboring cells, and resistant to non-specific protein deposition. With the molecular details of cell surface carbohydrates now in hand, adaptation of these structural motifs to synthetic materials is an appealing strategy for improving biocompatibility. The goal of this collaborative project between Prof. Bertozzi's research group, the Center for Advanced Materials at Lawrence Berkeley National Laboratory and Sunsoft Corporation was the design, synthesis and characterization of novel hydrogel polymers for improved soft contact lens materials. Our efforts were motivated by the urgent need for improved materials that allow extended wear, and essential feature for those whose occupation requires the use of contact lenses rather than traditional spectacles. Our strategy was to transplant the chemical features of cell surface molecules into contact lens materials so that they more closely resemble the tissue in which they reside. Specifically, we integrated carbohydrate molecules similar to those found on cell surfaces, and sulfoxide materials inspired by the properties of the carbohydrates, into hydrogels composed of biocompatible and manufacturable substrates. The new materials were characterized with respect to surface and bulk hydrophilicity, and
Best, Nigel; Drury, Laura; Wolffsohn, James S
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.
Boyraz, S; Güngör, I
To investigate the effects of the modulus of the lens material on the intraocular pressure measurement using the Tono-Pen XL applanation tonometer through soft contact lenses. Thirty eyes of 15 patients with myopia were evaluated. Intraocular pressure (IOP) measurements were performed using Tono-Pen XL directly over cornea, and subsequently through three soft contact lenses made up of different lens materials. All were -3.00 diopter soft contact lenses: lotrafilcon A with a low water content (24%) and high modulus (1.4 MPa) (CL-I), balafilcon A with a moderate water content (36%) and moderate modulus (1.1 MPa) (CL-II), and vifilcon A with a moderate water content (55%) and low modulus (0.79 MPa) (CL-III). IOP measurements through contact lenses were compared with each other, and with direct corneal measurements. The mean age of the patients (11 males and 4 females) was 26.86±5.62 years. All measurements obtained through CLs were significantly higher than the direct corneal measurements. The measurements through CLs differed by 4.61±0.54 mmHg (P=0,001), 2.9±0.46 mmHg (P=0.001), and 1.94±0.51 mmHg (P=0,003) for CL-I, CL-II and CL-III, respectively. In the paired comparisons of measurements through CLs, all comparisons were significant except the comparison of measurements through CL-II and CL-III (P=0.128). IOP measurements through silicone-hydrogel contact lenses with a high modulus and low water content were higher compared to the other contact lenses. While measuring IOP through CLs, the clinicians should consider the effect of the lens material and the features of the device used.
Karlgard, Caroline C. S.; Sarkar, Dilip K.; Jones, Lyndon W.; Moresoli, Christine; Leung, K. T.
The surface composition of hydrogel contact lenses that contain silicon-based monomers, PureVision™ (balafilcon A) and Focus ® Night&Day™ (lotrafilcon A), were investigated by X-ray photoelectron spectroscopy (XPS). Conventional and daily disposable hydrogel lenses based on hydroxyethyl methacrylate (HEMA) were also studied, with the commonly prescribed 1-day Acuvue ® lens (etafilcon A) used as a control. All the lenses were pre-washed and dehydrated by three different methods, including drying in air, drying in nitrogen or freezing with subsequent freeze-drying, before the XPS analysis. The lenses dried in air had more impurities on the surface, and the lenses that were freeze-dried lost transparency, suggesting that drying lenses in nitrogen is the preferred preparation method for XPS analysis. Surface compositions for all lens materials were obtained and this data can be used as a control/base-value for future analysis of the interactions of soft contact lens materials with chemicals such as drugs or tear components.
Hotta, Fumika; Eguchi, Hiroshi; Imai, Shoji; Miyamoto, Tatsuro; Mitamura-Aizawa, Sayaka; Mitamura, Yoshinori
To investigate the surfaces and principal elements of the colorants of cosmetically tinted contact lenses (Cos-CLs). 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. 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. 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.
Partner, Andrew M; Scott, Robert A H; Shaw, Penny; Coker, William J
Refractive devices used by aviators need to suit the aerospace environment or their failure can have serious implications. A relatively minor visual disability can result in loss of life and aircraft. We surveyed commonly occurring problems with the different types of refractive correction worn by Royal Air Force (RAF) aircrew over the previous 12 mo. We also asked if they had experienced any flight safety incidents (FSI) relating to their refractive correction. A retrospective anonymous questionnaire survey was given to 700 active aircrew occupationally graded as requiring corrective flying spectacles (CFS) or contact lenses (CL) for flying. 63% (443) of the questionnaires were completed. CL were worn by 53% of aircrew; 71% of them used daily disposable CL. CFS were worn by the remaining 47% of aircrew, 14% of whom used multifocal lenses. Of CFS wearers, 83% reported problems including misting, moving, discomfort, and conflict with helmet-mounted devices (HMD). CL-related ocular symptoms were reported in 67% of wearers including cloudy vision, dry eye, photophobia, red eyes, excessive mucus formation, CL movement, itching, and grittiness. No CL-related FSI were reported over the previous 12 mo compared with 5% CFS-related FSI (p < 0.001). The graded performance of CL for vision, comfort, handling, convenience, and overall satisfaction was significantly higher than for CFS. CFS are associated with problems in terms of comfort and safety. CL are well tolerated by aircrew, and deliver improved visual performance.
Lira, Madalena; Alves, Carlos; Botelho, Gabriela
In this work, four silicone-hydrogel contact lenses, Purevision® 2 (balafilcon A), Air Optix Aqua™ (lotrafilcon B), Acuvue® Oasys™ (senofilcon A) and Biofinity™ (comfilcon A), and one conventional lens, Acuvue® 2 (etafilcon A), were submitted during 5 weeks at a temperature of 37 °C under an air atmosphere. They were characterized initially and along exposure time in what concerns to the refractive index, water content, transmittance in the ultraviolet-visible region and chemical structure. From the results presented in this work it was possible to observe that in all lens the refractive index increases till 21 days and the water content decreased. At the end of the exposure these parameters are more variable depending on the lens studied. In what concerns to the transmittance in the ultraviolet-visible region it can be concluded that after exposure all lenses present a higher transmittance than initially. From this work it was possible to conclude that there were no significant changes in the wavenumbers where the main functional groups vibrate and in the intensity of the respective bands after 5 weeks of exposure.
Compañ, V; López-Alemany, A; Riande, E; Refojo, M F
The instrument oxygen transmissibility (IOT) of organosilicon hydrogels, measured by electrochemical procedures, is 5-10 times larger than that of conventional hydrogels. A method is described that allows the estimation of the oxygen tension at the lens-cornea interface for closed- and open-eyelids situations by combining the IOT of the hydrogels and corneal parameters such as corneal thickness, corneal permeability and oxygen flux across the cornea. From these results the biological oxygen apparent transmissibility (BOAT) is obtained, an important parameter which an multiplication with the pressure of oxygen on the external part of the lens gives the oxygen flux onto the cornea. Contact lenses with oxygen transmissibility higher than 100 Dk/t units [1 Dk/t unit=10(-9) [cm(3) O(2) (STp) cm(-2)s(-1)(mmHg)(-1)] posses a large oxygen tension at the lens-cornea interface that substantially reduces the oxygen flux onto the cornea. Lenses whose oxygen transmissibility is lower than 50 Dk/t units allow a rather small oxygen flux onto the cornea under closed eyelids condition that prevent their use for extended wear.
Rad, Maryam Shayani; Mohajeri, Seyed Ahmad
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.
Weeks, Andrea; Subbaraman, Lakshman N; Jones, Lyndon; Sheardown, Heather
The aim of this study was to determine the influence of hyaluronic acid (HA) on lysozyme sorption in model contact lenses containing varying amounts of methacrylic acid (MAA). One model conventional hydrogel (poly(2-hydroxyethyl methacrylate) (pHEMA)) and two model silicone hydrogels (pHEMA, methacryloxypropyltris(trimethylsiloxy)silane (pHEMA TRIS) and N,N-dimethylacrylamide, TRIS (DMAA TRIS)) lens materials were prepared with and without MAA at two different concentrations (1.7 and 5%). HA, along with dendrimers, was loaded into these model contact lens materials and then cross-linked with 1-ethyl-3-(3-dimethylamino propyl)-carbodiimide (EDC). Equilibrium water content (EWC), advancing water contact angle and lysozyme sorption on these lens materials were investigated. In the HA-containing materials, the presence (P < 0.05) and amount (P < 0.05) of MAA increased the EWC of the materials. For most materials, addition of MAA reduced the advancing contact angles (P < 0.05) and for all the materials, the addition of HA further improved hydrophilicity (P < 0.05). For the non-HA containing hydrogels, the presence (P < 0.05) and amount (P < 0.05) of MAA increased lysozyme sorption. The presence of HA decreased lysozyme sorption for all materials (P < 0.05). MAA appears to work synergistically with HA to increase the EWC in addition to improving the hydrophilicity of model pHEMA-based and silicone hydrogel contact lens materials. Hydrogel materials that contain HA have tremendous potential as hydrophilic, protein-resistant contact lens materials.
Silva, D; Fernandes, A C; Nunes, T G; Colaço, R; Serro, A P
The irritation/discomfort associated with the use of contact lenses (CLs) is often related to the eyelid-lens friction. Although the use of such devices is widespread, the information about the influence of the lacrimal fluid biomolecules on the tribological behavior of the CLs hydrogels is scarce. In this work, we investigated the effect of the presence of albumin and cholesterol in the lubricant medium, on the frictional response of two model hydrogels for CLs: a hydroxyethylmethacrylate based hydrogel, HEMA/PVP, and a silicone based one, TRIS/NVP/HEMA. Tribological experiments were done in a nanotribometer, in water and in the presence of solutions of those biomolecules. It was observed a significant increase of the friction coefficient (μ) for HEMA/PVP when the lubricant contains cholesterol, and for TRIS/NVP/HEMA when it contains albumin. Solid-state NMR and DSC analysis revealed that HEMA/PVP hydrated in cholesterol solution has a lower amount of free and loosely bound water than the hydrogel hydrated in water. Therefore, a smaller amount of water shall be released into the contact region during the friction tests with cholesterol solution, leading to a thinner film in the contact zone, and consequently to a higher μ. Concerning TRIS/NVP/HEMA, QCM-D studies showed that this hydrogel adsorbs less albumin than HEMA/PVP and that the formed film is more rigid, which can explain the increase of μ. The obtained results contribute to understand the influence of lacrimal fluid composition on the tribological behavior of CLs materials, being relevant for the selection and optimization of these devices. Understanding the tribological behavior of contact lenses (CLs) materials in contact with the lacrimal fluid and the role of its components is of major importance to optimize the comfort and overall success of these devices. Nevertheless, the available information on this subject in the literature is scarce. In this work, the effect of albumin and cholesterol (two of
Weeks, Andrea; Morrison, David; Alauzun, Johan G; Brook, Michael A; Jones, Lyndon; Sheardown, Heather
Photocrosslinkable methacrylated hyaluronic acid (HA) was prepared and incorporated into model conventional and silicone hydrogel contact lenses as an internal wetting agent. The molecular weight of the HA, the degree of methacrylation as well as the amount (0.25 to 1.0 wt %) incorporated were varied. The HA-containing hydrogels were analyzed using a variety of techniques including water contact angles, equilibrium water content (EWC), and lysozyme sorption. The presence of HA could be detected in the materials using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy-attenuated total reflectance. The materials containing methacrylated HA had improved hydrophilicity and reduced lysozyme sorption. Effects of modified HA on EWC were dependent upon the materials but generally increased water uptake. Increased mobility of the HA associated with a lower molecular weight and lower degree of methacrylation was found to be more effective in improving hydrophilicity and decreasing lysozyme sorption than the less mobile HA. All results found suggest that photocrosslinkable HA has significant potential in contact lens applications. Copyright © 2011 Wiley Periodicals, Inc.
Filipecki, Jacek; Kocela, Agnieszka; Korzekwa, Witold
Polymer materials based on hydrogel and silicone-hydrogel materials are commonly used in ophthalmology. It is important to research the structure of these materials, mainly the prevalence of free volumes. The study has been conducted in order to determine the presence of free volume gaps in the structure of polymer hydrogel and silicone-hydrogel contact lenses. In addition, to demonstrate differences in the occurrence of free volumes between types of represented contact lenses. Three different hydrogel and three different silicone-hydrogel polymer contact lenses were used as research material. The study was done by means of positron annihilation lifetime spectroscopy (PALS). As a result of the performed measurements, a graphical curve resulted which describes the relationship between the number of the annihilation acts in the time function. The study revealed the existence of three τ1, τ2 and τ3 components. Significant changes were observed in the ortho-positronium long life component τ3 and their intensities between the examined polymer contact lenses. The conducted study using the Tao-Eldrup model indicates the presence of free volume holes in all research materials. The results lead to the following connection: contact lenses of higher oxygen permeability coefficient (silicone-hydrogel contact lenses) have more and larger free volumes than contact lenses of less oxygen permeability coefficient (hydrogel contact lenses).
Scholtz, Sibylle K; Auffarth, Gerd U
Alhazen, ibn al-Haytham, (965 Basra - c. 1040 in Cairo) was a Muslim polymath who made significant contributions to the principles of optics, being the first to recognize the optical effect by transparent objects in the 11th century. His insights led to a fundamental revolution, enabling older presbyopic persons to read again. Today many more options are available to help visually impaired people correct their sight defects. This article will give an historical overview of the sight aids which are available today and will describe the very first beginnings of the development of the "reading stone" or "glasses". Further, it will also give a chronological overview of more modern techniques, e.g., intraocular lenses, contact lenses and the options of refractive surgery.
Schultz, C L; Pezzutti, M R; Silor, D; White, R
S. marcescens 8100 and P. aeruginosa 15442 were used to study bacterial adhesion to hydrogel contact lenses which had not been worn. Bacterial removal from unworn lens materials was assessed with a calibrated vortex device modified with a digital rpm readout and fitted with a test tube attachment (MVD). The MVD, which relies on a whirlpool-like force to remove the bacteria, showed that bacteria adhered to the same degree to etafilcon A, vifilcon A and polymacon lenses under standardized conditions. Tracking the isoenzyme patterns of these bacterial species over time showed instability of S. marcescens upon repeated passage. This instability was not evident with P. aeruginosa. Bacterial adhesion of P. aeruginosa 15442, to human worn and unworn etafilcon A materials was determined with a Modified Robbins Device. The MRD was closed off at both ends stopping medium and bacterial movement after 1 h of fluid flow over the lens surface. The results show that immediately following this 1-h period more bacteria adhere to unworn contact lenses than to worn lenses. However, bacterial counts were equivalent on worn and unworn lenses following 5 h of static incubation.
Cerretani, Colin; Peng, Cheng-Chun; Chauhan, A; Radke, C J
In addition to improving oxygen permeability, modern silicone-hydrogel (SiHy) soft contact lenses (SCLs) exceed a limiting diffusive ion permeability to aqueous sodium chloride. Below the ion-permeability threshold, siloxane-based SCLs are prone to bind against the corneal epithelium. Salt permeability is argued to reflect indirectly water hydraulic permeability. However, no quantitative explanation is available to date for a threshold salt permeability. We hypothesize that molecular salt diffusion through a SCL supports the postlens tear film (PoLTF) by enhancing water flow into the PoLTF from the cornea. Higher salt concentrations in the PoLTF raise the osmotic pressure there relative to that in the cornea increasing osmotic water withdrawal from the cornea. The proposed osmotic-withdrawal mechanism successfully predicts a self-consistent threshold lens salt permeability when thin-film attractive binding forces are introduced. For the first time, we present a quantitative picture for the possible origin of a threshold salt permeability in SCL manufacture. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Phan, Chau-Minh; Bajgrowicz, Magdalena; McCanna, David J; Subbaraman, Lakshman N; Jones, Lyndon
To evaluate the effects of two commercial silicone hydrogel contact lenses (CLs) soaked with natamycin (NA) or fluconazole (FL) on the growth of Candida albicans in an in vitro eye model. Three-D printed molds were used as a cast for making eye-shaped models comprising potato dextrose agar. Senofilcon A (SA) and lotrafilcon B (LB) CLs were incubated with either 2 mL of NA or FL at a concentration of 1 mg/mL for 24 hr. To simulate a fungal infection, the eye models were coated with C. albicans. The drug-soaked lenses were placed on top of the eye models. Seven experimental conditions were examined: (1) NA-SA, (2) NA-LB, (3) FL-SA, (4) FL-LB, (5) SA, (6) LB, and (7) control-no lens. At specified time points (t=1, 8, 16, 24, 48 hr), the agar eyes from each experimental condition were removed from the incubator and photographed. The yeast cells from the 24 and 48 hr time point were also analyzed using light microscopy. At 24 and 48 hr, there was considerable growth observed for all conditions except for the NA-SA and NA-LB conditions. When observed under the microscope at 24 and 48 hr, the morphology of the yeast cells in the FL-SA and SA condition were similar to that of the control (oval shaped). There was limited hyphae growth observed for LB and significant visible hyphae growth for the NA-LB group. For NA-SA, NA-LB, and FL-LB groups, the cells were significantly smaller compared with the control. For NA-SA and NA-LB, there was limited growth of C. albicans observed on the eye models even after 48 hr. Under the microscope, the cell morphology differ noticeably between each testing condition, and is dependent on drug-lens combinations.
Srinivasan, Sruthi; Otchere, Heinz; Yu, Mili; Yang, Jeffery; Luensmann, Doerte; Jones, Lyndon
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.
González-Méijome, José M; López-Alemany, Antonio; Almeida, José B; Parafita, Manuel A; Refojo, Miguel F
To investigate the in vitro dehydration process of conventional hydrogel and silicone-hydrogel contact lens materials. Eight conventional hydrogel and five silicone-hydrogel contact lenses were dehydrated under controlled environmental conditions on an analytical balance. Data were taken at 1-min intervals and dehydration curves of cumulative dehydration (CD), valid dehydration (VD), and dehydration rate (DR) were obtained. Several quantitative descriptors of the dehydration process were obtained by further processing of the information. Duration of phase I (r(2) = 0.921), CD at end of phase I (r(2) = 0.971), time to achieve a DR of -1%/min (r(2) = 0.946) were strongly correlated with equilibrium water content (EWC) of the materials. For each individual sample, the VD at different time intervals can be accurately determined using a 2nd order regression equation (r(2) > 0.99 for all samples). The first 5 min of the dehydration process show a relatively uniform average CD of about -1.5%/min. After that, there was a trend towards higher average CD for the following 15 min as the EWC of the material increases (r(2) = 0.701). As a consequence, average VD for the first 5 min displayed a negative correlation with EWC (r(2) = 0.835), and a trend towards uniformization among CL materials for the following periods (r(2) = 0.014). Overall, silicone-hydrogel materials display a lower dehydration, but this seems to be primarily due to their lower EWC. DR curves under the conditions of the present study can be described as a three-phase process. Phase I consists of a relatively uniform DR with a duration that ranges from 10 to almost 60 min and is strongly correlated with the EWC of the polymer as it is the CD during this phase. Overall, HEMA-based hydrogels dehydrate to a greater extent and faster than silicone-hydrogel materials. There are differences in water retention between lenses of similar water content and thickness that should be further investigated.
Abbey, Ashkan M.; Gregori, Ninel Z.; Surapaneni, Krishna; Miller, Darlene
Purpose While manufacturers recommend cleaning ophthalmic lenses with detergent and water and then a specific disinfectant, disinfectants are rarely used in ophthalmic practices. The aim of this pilot study was to evaluate the efficacy of detergent and water versus bleach, a recommended disinfectant, to eliminate common ocular bacteria and viruses from ophthalmic lenses. Methods Three bacterial strains (Staphylococcus epidermidis, Corynebacterium straitum, and methicillin-resistant Staphylococcus aureus (MRSA) and two viral strains (adenovirus and herpes simplex virus (HSV) type-1) were individually inoculated to 20 gonioscopy and laser lenses. Lenses were washed with detergent and water and then disinfected with 10% bleach. All lenses were cultured after inoculation, after detergent and water, and after the bleach. Bacterial cultures in thioglycollate broth were observed for 3 weeks and viral cultures for 2 weeks. The presence of viruses was also detected by multiplex polymerase chain reaction (PCR). Results All 20 lenses inoculated with Staphylococcus epidermidis, Corynebacterium straitum, adenovirus, and HSV-1 showed growth after inoculation, but no growth after detergent/water and after the bleach. All lenses showed positive HSV and adenovirus PCR after inoculation and negative PCR after detergent/water and after bleach. All MRSA contaminated lenses showed growth after inoculation and no growth after detergent and water. However, one lens showed positive growth after bleach. Conclusions Cleaning with detergent and water appeared to effectively eliminate bacteria and viruses from the surface of contaminated ophthalmic lenses. Further studies are warranted to design practical disinfection protocols that minimize lens damage. PMID:24747806
Kenley, Richard A; Filippone, Helena; Giske, Mai; Beidler, Dan; Vehige, Joseph; Fleitman, Jeffrey
To determine the equilibrium binding constant (EB) values of bimatoprost and tafluprost drug product formulations in contact with lotrafilcon A soft contact lenses and to characterize the importance of drug molecule hydrophobicity in controlling the binding interactions. Bimatoprost Ophthalmic Solution and Tafluprost Ophthalmic Solution (Saflutan) were incubated with lotrafilcon A lens material for timed intervals at 25°C and 37°C. Aliquots were withdrawn, filtered, and tested using reverse-phase ultrahigh-performance liquid chromatography with respect to [bimatoprost] or [tafluprost] remaining in the solution. A series of homologous dialkyl phthalate esters and a series of homologous p-hydroxybenzoic acid alkyl esters were also tested as reference compounds. Bimatoprost and tafluprost were rapidly (within 15 min) absorbed from the solution by lotrafilcon A lenses, reaching an equilibrium within 60 min. At any lens:solution (w/v) ratio, the extent of drug binding to lens material was greater for tafluprost than for bimatoprost. The log(EB) values correlated with solute octanol:water partition coefficient (logP) values, indicating that hydrophobic interactions are important in controlling solute partitioning into the lens material. This study established the quantitative relationships between tafluprost and bimatoprost binding to lotrafilcon A lenses. The fraction of bimatoprost or tafluprost that binds to lotrafilcon A increases with increasing lens:solution (w/v) ratio. For a 60 µL dose volume applied to a single contact lens, 16% of initially present bimatoprost remains in the solution, whereas only 6% of initially present tafluprost remains in the solution. These calculations clearly demonstrate that both drugs partition extensively into lotrafilcon A contact lens material. Although the clinical implications of such binding can only be surmised, it would seem prudent to caution contact lens wearers to remove the lenses before administering either
Hatzav, M; Bdolah-Abram, T; Ofri, R
Therapeutic soft contact lenses (TSCLs) are frequently used to support or protect the cornea during healing. Our aim was to quantitatively evaluate the efficacy of topical medications in TSCL-fitted dogs and determine whether it is affected by the presence of TSCLs. In Phase I, pupil diameter was measured in eyes treated with tropicamide and in eyes covered with TSCLs and then treated with tropicamide, with 1-week intervals between sessions. In Phase II, intraocular pressure (IOP) was measured in uncovered and TSCL-covered eyes treated with latanoprost, with 1-week intervals between sessions. Tropicamide caused significant mydriasis in both uncovered and TSCL-covered eyes (P = 0.005). On the other hand, latanoprost caused a significant decrease in IOP when applied to uncovered eyes (P = 0.002), but had no significant effect on IOP when applied to TSCL-covered eyes (P = 0.7). As we used the same dogs and identical TSCLs throughout the study, we conclude that the different outcomes of the two drugs are due to properties of the drugs themselves, or their formulations, affecting their interaction with the TSCLs. The clinical efficacy of topical drugs applied to TSCL-covered eyes may have to be determined for each drug and/or formulation. © 2015 John Wiley & Sons Ltd.
Rathi, Varsha M; Taneja, Mukesh; Dumpati, Srikanth; Mandathara, Preeji S; Sangwan, Virender S
To report the rare coexistence of keratoconus and Stevens-Johnson syndrome (SJS) managed with scleral contact lenses (ScCLs). This is a retrospective case series. Five patients (9 eyes) who had coexisting SJS and corneal ectasia were identified from the database during the 2-year period. Diagnosis of SJS was based on a positive history of drug reactions, signs of ocular surface disease, and the presence of keratinization of lid margins. Keratoconus was diagnosed by slit-lamp biomicroscopy. Five eyes of 3 patients had coexisting SJS and keratoconus and were dispensed with ScCLs (PROSE, prosthetic replacement of the ocular surface ecosystem; Boston Foundation for Sight, Needham Heights, MA). All these patients had photophobia. Visual acuity improved in all these patients with ScCL wear. Two patients (4 eyes) were excluded from this study because they had SJS with generalized corneal thinning from limbus to limbus, corneal opacification, and pannus. One patient developed deep vessels in the cornea on prolonged ScCL wear. Reduction in the ScCL wear schedule and change of material with a higher Dk resulted in regression of vascularization. Case 3 developed conjunctival congestion and was uncomfortable wearing ScCLs, although visual acuity was 20/40. He discontinued using ScCL wear. Keratoconus, a noninflammatory condition of the cornea coexisted with inflammatory SJS. Managing such patients with ScCLs may improve vision and comfort.
Paradiso, P; Colaço, R; Mata, J L G; Krastev, R; Saramago, B; Serro, A P
In this article, liposome-based coatings aiming to control drug release from therapeutic soft contact lenses (SCLs) materials are analyzed. A PHEMA based hydrogel material loaded with levofloxacin is used as model system for this research. The coatings are formed by polyelectrolyte layers containing liposomes of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and DMPC + cholesterol (DMPC + CHOL). The effect of friction and temperature on the drug release is investigated. The aim of the friction tests is to simulate the blinking of the eyelid in order to verify if the SCLs materials coated with liposomes are able to keep their properties, in particular the drug release ability. It was observed that under the study conditions, friction did not affect significantly the drug release from the liposome coated PHEMA material. In contrast, increasing the temperature of release leads to an increase of the drug diffusion rate through the hydrogel. This phenomenon is recorded both in the control and in the coated samples. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1799-1807, 2017. © 2016 Wiley Periodicals, Inc.
Torrent-Burgués, J; Sanz, F
Contact lenses (CLs) are of common use and the biocompatibility, topography and mechanical properties of the used materials are of major importance. The objective of this contribution is to apply the AFM in mode Peak Force to obtain surface topography and mechanical characteristics of un-worn CLs of different materials. One material of hydrogel, two of siloxane-hydrogel and one of rigid gas-permeable were used in the study. The results obtained with different materials have been compared, at a nanoscopic level, and the conclusions are diverse. There is no significant influence of the two environments used to measure the characteristics of the CLs, either water or saline solution. The pHEMA hydrogel CL (Polymacon of Soflens) shows the highest values of roughness, adhesion and elastic modulus. The siloxane-hydrogel CL named Asmofilcon A of PremiO presents the lowest values of mean roughness (Ra), root-mean-square roughness (RMS or Rq), adhesion (Adh) and elastic modulus (Ym), meanwhile the siloxane-hydrogel CL named Lotrafilcon B of Air Optix presents the lowest value of skewness (Rsk) and the rigid gas-permeable CL, named RXD, presents the lowest values of kurtosis (Rku) and maximum roughness (Rmax). Copyright © 2014 Elsevier B.V. All rights reserved.
Mousavi, Maryam; Jesus, Danilo A; Garaszczuk, Izabela K; Szczesna-Iskander, Dorota H; Iskander, D Robert
To evaluate the clinical value of non-invasive keratograph tear film breakup time (NIKBUT) in the assessment of pre-corneal and pre-lens tear film quality for prescribing contact lenses (CLs). Forty-six subjects aged 25.5±4.3 (mean±standard deviation) years were recruited. Visual acuity (VA), anterior eye health checks and NIKBUT were evaluated. On the following day, subjects were fitted with a daily Silicon Hydrogel (SiHy) CL in one eye and a Hydrogel (Hy) CL in the other. After four hours one material for both eyes was chosen based on a qualitative analysis which included VA, CL fitting and comfort. Information about the first and the mean NIKBUT was then contrasted against the prescription decision. Thirty-four subjects were fitted with SiHy and twelve with Hy CL. No statistically significant differences were found for both NIKBUT parameters between left and right eye at baseline (p=0.38 and p=0.50, respectively) and post four hours of CL wear (p=0.61 and p=0.06). The chosen lens did not always correspond to longer NIKBUT. In 39.1% and 34.8% of cases (i.e., 18 and 16 out of 46), there was a match between prescription decision and the first and the mean NIKBUT results, respectively. Although there is no evidence whether tear film surface quality measurement has a superior diagnostic values compared to other traditional clinical measures used in practice, NIKBUT measurements have provided additional information that could be of interest during CL fit. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Pimenta, A F R; Ascenso, J; Fernandes, J C S; Colaço, R; Serro, A P; Saramago, B
Optimization of drug delivery from drug loaded contact lenses assumes understanding the drug transport mechanisms through hydrogels which relies on the knowledge of drug partition and diffusion coefficients. We chose, as model systems, two materials used in contact lens, a poly-hydroxyethylmethacrylate (pHEMA) based hydrogel and a silicone based hydrogel, and three drugs with different sizes and charges: chlorhexidine, levofloxacin and diclofenac. Equilibrium partition coefficients were determined at different ionic strength and pH, using water (pH 5.6) and PBS (pH 7.4). The measured partition coefficients were related with the polymer volume fraction in the hydrogel, through the introduction of an enhancement factor following the approach developed by the group of C. J. Radke (Kotsmar et al., 2012; Liu et al., 2013). This factor may be decomposed in the product of three other factors E HS , E el and E ad which account for, respectively, hard-sphere size exclusion, electrostatic interactions, and specific solute adsorption. While E HS and E el are close to 1, E ad >1 in all cases suggesting strong specific interactions between the drugs and the hydrogels. Adsorption was maximal for chlorhexidine on the silicone based hydrogel, in water, due to strong hydrogen bonding. The effective diffusion coefficients, D e , were determined from the drug release profiles. Estimations of diffusion coefficients of the non-adsorbed solutes D=D e ×E ad allowed comparison with theories for solute diffusion in the absence of specific interaction with the polymeric membrane. Copyright Â© 2016 Elsevier B.V. All rights reserved.
Yañez, Fernando; Martikainen, Lahja; Braga, Mara E M; Alvarez-Lorenzo, Carmen; Concheiro, Angel; Duarte, Catarina M M; Gil, Maria H; de Sousa, Hermínio C
The aim of this work was to develop an innovative supercritical fluid (SCF)-assisted molecular imprinting method to endow commercial soft contact lenses (SCLs) with the ability to load specific drugs and to control their release. This approach seeks to overcome the limitation of the common loading of preformed SCLs by immersion in concentrated drug solutions (only valid for highly water soluble drugs) and of the molecular imprinting methods that require choice of the drug before polymerization and thus to create drug-tailored networks. In particular, we focused on improving the flurbiprofen load/release capacity of daily wear Hilafilcon B commercial SCLs by the use of sequential SCF flurbiprofen impregnation and extraction steps. Supercritical carbon dioxide (scCO2) impregnation assays were performed at 12.0 MPa and 40 °C, while scCO2 extractions were performed at 20.0 MPa and 40 °C. Conventional flurbiprofen sorption and drug removal experiments in aqueous solutions were carried out for comparison purposes. SCF-processed SCLs showed a recognition ability and a higher affinity for flurbiprofen in aqueous solution than for the structurally related ibuprofen and dexamethasone, which suggests the creation of molecularly imprinted cavities driven by both physical (swelling/plasticization) and chemical (carbonyl groups in the network with the C-F group in the drug) interactions. Processing with scCO2 did not alter some of the critical functional properties of SCLs (glass transition temperature, transmittance, oxygen permeability, contact angle), enabled the control of drug loaded/released amounts (by the application of several consecutive processing cycles) and permitted the preparation of hydrophobic drug-based therapeutic SCLs in much shorter process times than those using conventional aqueous-based molecular imprinting methods. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Osuagwu, Uchechukwu L; Ogbuehi, Kelechi C
To assess the transmittance, in the 200-700nm electromagnetic radiation spectrum, by popularly used tinted soft contact lenses (CLs). The spectra transmittances of ultraviolet (UV)-blocking (I Day Acuvue Define, Freshlook ONE DAY) and non-UV-blocking (Durasoft 3, Tutti, and NeoCosmo) tinted soft CLs were tested. The transmittance of each lens, including nine different colors of Freshlook CL was recorded on spectrophotometer, and the data used to also calculate a UV protection factor (PF) for each lens brand tested, with a higher value indicating a higher level of protection. The UV-blocking CLs significantly reduced UVC, UVB & UVA transmission and thereby meet the American National Standards Institution standard for class 2 UV blockers: a maximum of 30% transmittance of UVA and 5% transmittance of UVB wavelengths. In contrast, the Durasoft 3, Tutti, and NeoCosmo CLs demonstrated negligible UV-blockage. The Acuvue Define CL offered the greatest protection from UVC (PF=69) and UVB (PF=55), but with only 35% luminous transmittance, while the Freshlook CL (especially gemstone green) offered the best protection from UVA (PF=24) and showed about 55% translucency. Overall, the UV-blocking CLs performed equally well across the UV spectrum. Different colors of Freshlook CL transmitted statistically and clinically significantly different amounts of visible light but similar amounts of UVR. Freshlook and Acuvue Define CLs which are designated as UV-blockers significantly reduced UVR transmission to safe levels whereas Tutti, NeoCosmo and Durasoft 3 did not. Transmission within the Freshlook CL family was more dependent on color in the visible light spectrum, but not in the UV-spectrum, where the gemstone green performing best among the tested colors. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Weber, Sarah La Porta; Hazarbassanov, Rossen Mihaylov; Nasaré, Alex; Gomes, José Álvaro Pereira; Hofling-Lima, Ana Luisa
To evaluate conjunctival impression cytology and HLADR expression changes after wearing scleral contact lenses (ScCLs) for moderate to severe dry eye disease (DED). Prospective interventional case series. Forty-one eyes from 25 patients with moderate to severe DED were evaluated for Esclera ScCL treatment. Best-corrected visual acuity (BCVA) and slit-lamp findings were assessed. Impression cytology specimens were obtained from DED patients at the baseline and after wearing ScCLs for 12 months. The impression cytology specimens were analyzed using morphological results score, and HLA-DR positive cells were detected and quantified. The values were compared to assess the IC changes after wearing ScCLs. Forty-one eyes from 25 patients were fitted with ScCLs to manage DED. The underlying diseases were Stevens-Johnson syndrome (22 eyes), Sjogren's syndrome (11 eyes), graft-versus-host disease (2 eyes), dry eye after keratomileusis (2 eyes) and undifferentiated ocular surface disease (4 eyes). The HE-PAS impression cytology score did not differ significantly before and after wearing ScCLs for 12 months in DED patients (p>0.05). The percentage of eyes expressing the HLA-DR antigen in the temporal conjunctiva after wearing ScCL for 12 months significantly increased in patients with Sjogren's syndrome (11.11% to 66.66%; p=0.0498). In groups with Stevens Johnson syndrome and other ocular surface disorders, we did not observe statistically significant differences (p>0.05). The ScCLs did not change the parameters used to evaluate inflammatory processes, which were measured using conjunctival impression cytology and HLA-DR expression, except in Sjogren syndrome, in which there was an unexpected increase in HLA expression. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Engle, Andrew T; Laurent, John M; Schallhorn, Steven C; Toman, Steven D; Newacheck, James S; Tanzer, David J; Tidwell, James L
To compare the efficacy of 2 types of bandage contact lenses (BCLs) after photorefractive keratectomy (PRK). Navy Refractive Surgery Center, Naval Medical Center San Diego, San Diego, California, USA. In this prospective study, 100 patients received PRK in both eyes. Each patient received a BCL composed of etafilcon A (Acuvue [ACV], Vistakon Inc.) (14.0 diameter, 8.4/8.8 base curve) in 1 eye and lotrafilcon A (Focus Night & Day [N&D], Ciba Vision) (13.8 diameter, 8.4/8.6 base curve) in the fellow eye. The patient was masked to the lens type in each eye. The postoperative medication regimen was the same with both lenses. The epithelial defect size and subjective level of discomfort were measured at surgery and daily after surgery until both eyes had reepithelialized and the lenses were removed. The mean epithelial defect size at surgery was similar with both BCLs (ACV 57.07 mm(2) and N&D 57.53 mm(2); P=.422). On postoperative days 1 and 2, the mean defect size was significantly smaller in eyes with the N&D lens (day 1, ACV 21.53 and N&D 18.74; day 2, ACV 3.62 and N&D 2.12) (paired t test, P<.001). On day 1, no eye had completely reepithelialized; on day 2, 20 eyes with N&D lenses and 13 eyes with ACV lenses had. On day 3, 70 eyes with N&D lenses and 66 eyes with ACV lenses had reepithelialized. The mean discomfort index was significantly higher in the eyes with ACV lenses on days 1 and 2 (paired t test, P<.001 and P<.002, respectively). Topical nonpreserved tetracaine was used significantly more often in eyes with ACV lenses on days 1, 2, and 3 (paired t test, P<.001, P<.008, P<.003, respectively). No correlation between the use of tetracaine in the first 24 hours and the rate of reepithelialization was noted (R(2)=0.0025 for ACV and R(2)=0.0003 for N&D). The lotrafilcon A lens resulted in significantly faster corneal reepithelialization and reduced patient discomfort in most patients during the first 48 hours after PRK.
Kim, Eon; Bakaraju, Ravi C; Ehrmann, Klaus
To evaluate the repeatability of power profiles measured on NIMO TR1504 (Lambda-X, Belgium) and investigate the effects of lens decentration on the power profiles for single vision (SV), bifocal (BF) and multifocal (MF) contact lenses. Accuracy of the sphere power was evaluated using single vision BK-7 calibration glass lenses of six minus and six plus powers. Three SV and four BF/MF contact lenses - three lenses each, were measured five times to calculate the coefficients of repeatability (COR) of the instrument. The COR was computed for each chord position, lens design, prescription power and operator. One lens from each type was measured with a deliberate decentration up to ±0.5mm in 0.1mm steps. For all lenses, the COR varied across different regions of the half-chord position. In general, SV lenses showed lower COR compared to the BF/MF group lenses. There were no noticeable trends of COR between prescription powers for SV and BF/MF lenses. The shape of the power profiles was not affected when lenses were deliberately decentered for all SV and PureVision MF lenses. However, for Acuvue BF lenses, the peak to trough amplitude of the power profiles flattened up to 1.00D. The COR across the half-chord of the optic zone diameter was mostly within clinical relevance except for the central 0.5mm half-chord position. COR were dependent on the lens type, whereby BF/MF group produced higher COR than SV lenses. The effects of deliberate decentration on the shape of power profiles were pronounced for lenses where the profiles had sharp transitions of power. Copyright © 2015 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.
Kim, Eon; Bakaraju, Ravi C.; Ehrmann, Klaus
Purpose To evaluate the repeatability of power profiles measured on NIMO TR1504 (Lambda-X, Belgium) and investigate the effects of lens decentration on the power profiles for single vision (SV), bifocal (BF) and multifocal (MF) contact lenses. Methods Accuracy of the sphere power was evaluated using single vision BK-7 calibration glass lenses of six minus and six plus powers. Three SV and four BF/MF contact lenses – three lenses each, were measured five times to calculate the coefficients of repeatability (COR) of the instrument. The COR was computed for each chord position, lens design, prescription power and operator. One lens from each type was measured with a deliberate decentration up to ±0.5 mm in 0.1 mm steps. Results For all lenses, the COR varied across different regions of the half-chord position. In general, SV lenses showed lower COR compared to the BF/MF group lenses. There were no noticeable trends of COR between prescription powers for SV and BF/MF lenses. The shape of the power profiles was not affected when lenses were deliberately decentered for all SV and PureVision MF lenses. However, for Acuvue BF lenses, the peak to trough amplitude of the power profiles flattened up to 1.00 D. Conclusion The COR across the half-chord of the optic zone diameter was mostly within clinical relevance except for the central 0.5 mm half-chord position. COR were dependent on the lens type, whereby BF/MF group produced higher COR than SV lenses. The effects of deliberate decentration on the shape of power profiles were pronounced for lenses where the profiles had sharp transitions of power. PMID:26590009
Paradiso, Patrizia; Chu, Virginia; Santos, Luís; Serro, Ana Paula; Colaço, Rogério; Saramago, Benilde
Although the plasma technology has long been applied to treat contact lenses, the effect of this treatment on the performance of drug-loaded contact lenses is still unclear. The objective of this work is to study the effect of nitrogen plasma treatment on two drug-loaded polymeric formulations which previously demonstrated to be suitable for therapeutic contact lenses: a poly-hydroxyethylmethacrylate (pHEMA) based hydrogel loaded with levofloxacin and a silicone-based hydrogel loaded with chlorhexidine. Modifications of the surface and the optical properties, and alterations in the drug release profiles and possible losses of the antimicrobial activities of the drugs induced by the plasma treatment were assessed. The results showed that, depending on the system and on the processing conditions, the plasma treatment may be beneficial for increasing wettability and refractive index, without degrading the lens surface. From the point of view of drug delivery, plasma irradiation at moderate power (200 W) decreased the initial release rate and the amount of released drug, maintaining the drug activity. For lower (100 W) and higher powers (300 W), almost no effect was detected because the treatment was, respectively, too soft and too aggressive for the lens materials. © 2014 Wiley Periodicals, Inc.
B. O., Ajayi; F.E., Kio; F.D., Otajevwo
Fifty conjunctival swab samples collected from ELISA confirmed HIV/AIDS seropositive patients who were referred to the HIV/AIDS laboratories of the University of Benin Teaching Hospital and Central Hospital both based in Benin City, Nigeria were aseptically cultured on appropriate media by standard methods. The resulting isolates/strains, after identification by standard methods, were tested for their ability to adhere to two hydrophobic non-ionic daily wear silicone hydrogel soft contact lenses (i.e. lotrafilcon B, WC 33% and polymacon, WC 38%) as well as to two hydrophilic ionic conventional extended wear silicone hydrogel soft contact lenses (i.e. methafilcon A, WC 55% and omafilcon A, WC 60%) by the adhesiveness/slime production modified vortex/Robin device method. Evidence of adhesiveness/slime production was indicated by presence of a visible stained film lining the surface of the contact lens which was measured and recorded as strong or weak according to the density of the adhered bacterial film. Fourteen (28.0%) Staphylococcus aureus strains and 10 (20.0%) Pseudomonas aeruginosa strains were obtained among other organisms. Staphylococcus aureus strains adhered in decreasing order to lotrafilcon B (55.4 ± 4.7), polymacon (46.4 ± 8.4), methfilcon A (46.4 ± 8.4) and omafilcon A (25.0 ± 6.4) with no significant difference in adhesive strengths of individual strains (P > 0.05). Pseudomonas aeruginosa strains also recorded decreasing adhesive strengths to lotrafilcon B (37.5 ± 8.2), polymacon (28.6 ± 6.3), methafilcon A (26.8 ± 5.5) and omafilcon A (23.2 ± 5.5) also with no significant difference in adhesive strengths of individual strains (P > 0.05). Attachment strengths of Staph. aureus strains to all four contact lenses were higher than those of Pseudomonas aeruginosa strains. Both organisms adhered most to hydrophobic lotrafilcon B and least to hydrophilic omafilcon A. This invitro adhesion studies revealed that daily wear silicone hydrogel low water
Ajayi, B O; Kio, F E; Otajevwo, F D
Fifty conjunctival swab samples collected from ELISA confirmed HIV/AIDS seropositive patients who were referred to the HIV/AIDS laboratories of the University of Benin Teaching Hospital and Central Hospital both based in Benin City, Nigeria were aseptically cultured on appropriate media by standard methods. The resulting isolates/strains, after identification by standard methods, were tested for their ability to adhere to two hydrophobic non-ionic daily wear silicone hydrogel soft contact lenses (i.e. lotrafilcon B, WC 33% and polymacon, WC 38%) as well as to two hydrophilic ionic conventional extended wear silicone hydrogel soft contact lenses (i.e. methafilcon A, WC 55% and omafilcon A, WC 60%) by the adhesiveness/slime production modified vortex/Robin device method. Evidence of adhesiveness/slime production was indicated by presence of a visible stained film lining the surface of the contact lens which was measured and recorded as strong or weak according to the density of the adhered bacterial film. Fourteen (28.0%) Staphylococcus aureus strains and 10 (20.0%) Pseudomonas aeruginosa strains were obtained among other organisms. Staphylococcus aureus strains adhered in decreasing order to lotrafilcon B (55.4 ± 4.7), polymacon (46.4 ± 8.4), methfilcon A (46.4 ± 8.4) and omafilcon A (25.0 ± 6.4) with no significant difference in adhesive strengths of individual strains (P > 0.05). Pseudomonas aeruginosa strains also recorded decreasing adhesive strengths to lotrafilcon B (37.5 ± 8.2), polymacon (28.6 ± 6.3), methafilcon A (26.8 ± 5.5) and omafilcon A (23.2 ± 5.5) also with no significant difference in adhesive strengths of individual strains (P > 0.05). Attachment strengths of Staph. aureus strains to all four contact lenses were higher than those of Pseudomonas aeruginosa strains. Both organisms adhered most to hydrophobic lotrafilcon B and least to hydrophilic omafilcon A. This invitro adhesion studies revealed that daily wear silicone hydrogel low water
Maulvi, Furqan A; Shaikh, Anjum A; Lakdawala, Dhara H; Desai, Ankita R; Pandya, Mihir M; Singhania, Sulabh S; Vaidya, Rutvi J; Ranch, Ketan M; Vyas, Bhavin A; Shah, Dinesh O
Contact lenses are widely used for ophthalmic drug delivery, but incorporation of drug or formulation in the contact lenses affects its optical and physical property. In the present study, we have designed a novel hyaluronic acid (HA)-laden ring implant contact lenses (modified cast moulding method), to circumvent the changes in critical lens property. The objective was to improve the ocular residence time of HA, by providing sustained ocular HA delivery through implant contact lenses for the treatment of dry eye syndrome. Optimization of HA-implant was carried out using 32 factorial design by tailoring the amount of cross linker and thickness of implant, to achieve sustained HA release with constraint on effective ion diffusivity. The in vivo pharmacokinetic study in rabbit tear fluid showed sustained HA release up to 15days, by fabricating implant (80μgHA loading) with 78.4μm thickness (total thickness of lens=100μm) using 0.925% of cross linker, with effective ion diffusivity>1.5×10-6mm2/min. In vivo efficacy study in benzalkonium chloride induced dry eye syndrome rabbits showed faster healing with implant contact lenses in comparison to positive control group. The study demonstrated the promising potential of implantation technology to deliver hyaluronic acid without compromising optical and physical properties of contact lens. The limitation of contact lenses to be used as therapeutic device for controlled drug delivery is focused in this study. Incorporation of drug or formulation in the biomaterial affects the optical and physical property of contact lenses. The significance of project was to design a novel hyaluronic acid-laden ring implant contact lenses, to by-pass the changes in critical property of biomaterial. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Abbey, Ashkan M; Gregori, Ninel Z; Surapaneni, Krishna; Miller, Darlene
Although manufacturers recommend cleaning ophthalmic lenses with detergent and water and then with a specific disinfectant, disinfectants are rarely used in ophthalmic practices. The aim of this pilot study was to evaluate the efficacy of detergent and water versus that of bleach, a recommended disinfectant, to eliminate common ocular bacteria and viruses from ophthalmic lenses. Three bacterial strains (Staphylococcus epidermidis, Corynebacterium straitum, and methicillin-resistant Staphylococcus aureus and 2 viral strains (adenovirus and herpes simplex virus [HSV] type-1) were individually inoculated onto 20 gonioscopy and laser lenses. The lenses were washed with detergent and water and then disinfected with 10% bleach. All the lenses were cultured after inoculation, after washing with detergent and water, and after disinfecting with the bleach. Bacterial cultures in thioglycollate broth were observed for 3 weeks, and viral cultures were observed for 2 weeks. The presence of viruses was also detected by multiplex polymerase chain reaction (PCR). All 20 lenses inoculated with S. epidermidis, C. straitum, adenovirus, and HSV-1 showed growth after inoculation but no growth after washing with detergent/water and after disinfecting with the bleach. All lenses showed positive HSV and adenovirus PCR results after inoculation and negative PCR results after washing with detergent/water and after disinfecting with bleach. All methicillin-resistant S. aureus-contaminated lenses showed growth after inoculation and no growth after washing with detergent and water. However, 1 lens showed positive growth after disinfecting with bleach. Cleaning with detergent and water seemed to effectively eliminate bacteria and viruses from the surface of contaminated ophthalmic lenses. Further studies are warranted to design practical disinfection protocols that minimize lens damage.
Szczesna-Iskander, Dorota H
Recently, a new water gradient silicone hydrogel material has been introduced for a daily disposable lens. The aim of this study was to assess, in vivo, the prelens tear film surface quality (TFSQ) of this new lens in comparison with that of another daily disposable lens from the same manufacturer. Eleven subjects wore two pairs of hydrogel nelfilcon A and silicone hydrogel delefilcon A lenses in two nonconsecutive days. The noninvasive lateral shearing interferometry was used to analyze the prelens tear film and distinguish between different contact lens materials. Measurements were taken in natural blinking conditions after 6 hours of wear. Additionally, the subjective comfort was evaluated. The presence of both lenses resulted in a TFSQ reduction as compared with the bare eye condition. Statistically significant (Wilcoxon rank sum test, P<0.012) smaller change in TFSQ was introduced by the water gradient material than the high water content material. A statistically significant correlation between the TFSQ results of the two lenses was found (Pearson correlation coefficient R=0.8, P<0.003), indicating high linearity of the measurement methodology with respect to the tested lens material. The correlation of subjective comfort in lenses was lower and found to be insignificant (R=0.6, P>0.05). Although the prelens TFSQ is not always directly proportional to the lens water content, the results of the in vivo study showed that the new water gradient silicone hydrogel material impact less TFSQ as compared with its predecessor.
Inamoto, Yoshihiro; Sun, Yi-Chen; Flowers, Mary E D; Carpenter, Paul A; Martin, Paul J; Li, Peng; Wang, Ruikang; Chai, Xiaoyu; Storer, Barry E; Shen, Tueng T; Lee, Stephanie J
To examine safety and efficacy of bandage soft contact lenses (BSCLs) for ocular chronic graft-versus host disease (GVHD), we conducted a phase II clinical trial. Extended-wear BSCLs were applied under daily topical antibiotic prophylaxis. Patients completed standardized symptom questionnaires at enrollment and at 2 weeks, 4 weeks, and 3 months afterward. Ophthalmologic assessment was performed at enrollment, at 2 weeks, and afterward as medically needed. Assessments at follow-up were compared with baseline by paired t-test. Nineteen patients with ocular GVHD who remained symptomatic despite conventional treatments were studied. The mean Lee eye subscale score was 75.4 at enrollment and improved significantly to 63.2 at 2 weeks (P = .01), to 61.8 at 4 weeks (P = .005), and to 56.3 at 3 months (P = .02). The ocular surface disease index score and 11-point eye symptom ratings also improved significantly. According to the Lee eye subscale, clinically meaningful improvement was observed in 9 patients (47%) at 2 weeks, in 11 patients (58%) at 4 weeks, and in 9 patients (47%) at 3 months. Visual acuity improved significantly at 2 weeks compared with enrollment values. Based on slit lamp exam at 2 weeks, punctate epithelial erosions improved in 58% of the patients, showed stability in 16%, and worsened in 5%. No corneal ulceration or ocular infection occurred. BSCLs are a widely available, safe, and effective treatment option that improves manifestations of ocular GVHD in approximately 50% of patients. This study was registered at www.clinicaltrials.gov as NCT01616056. Copyright © 2015 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.
Luensmann, Doerte; Yu, Mili; Yang, Jeffery; Srinivasan, Sruthi; Jones, Lyndon
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.
Gomes, Thiago dos Santos; Magnet, Angela; Izquierdo, Fernando; Vaccaro, Lucianna; Redondo, Fernando; Bueno, Sara; Sánchez, Maria Luisa; Angulo, Santiago; Fenoy, Soledad; Hurtado, Carolina; del Aguila, Carmen
Purpose Acanthamoeba keratitis (AK) is a painful and potentially blinding corneal infection caused by Acanthamoeba spp. In Madrid, environmental studies have demonstrated a high presence of these free-living amoebae in tap water. Since most of AK cases occur in contact lenses (CL) wearers with inadequate hygiene habits, the presence of Acanthamoeba in discarded CL has been studied and compared with other common etiological agents of keratitis, such as Pseudomonas aeruginosa and Staphylococcus aureus. Methods One hundred and seventy-seven healthy individuals from Madrid contributed their discarded CL and answered a questionnaire on hygiene habits. DNA was extracted from the CL solution and analyzed by real-time PCR for Acanthamoeba, Pseudomonas aeruginosa and Staphylococcus aureus. These CL and their solutions were also cultured on non-nutrient agar to isolate Acanthamoeba. Results Among the 177 samples, Acanthamoeba DNA was detected in 87 (49.2%), P. aeruginosa DNA in 14 (7.9%) and S. aureus DNA in 19 (10.7%). Cultivable amoebae, however, were observed in only one sample (0.6%). This isolate was genotyped as T4. The habits reported by this CL owner included some recognized risk factors for AK, but in this study only the practice of “not cleaning the CL case” presented some statistical significant association with Acanthamoeba DNA presence. Detection of the investigated bacterial DNA did not demonstrate statistical significant association with the studied practices, but the presence of P. aeruginosa revealed a possible inhibition of Acanthamoeba in these samples. Conclusions The PCR results suggest a high presence of Acanthamoeba spp. in healthy CL wearers from Madrid, but we can assume that CL solutions are properly disinfecting the CL since only 1.1% of the positive PCR samples correspond to viable amoebae and, after four years, only one participant reported stronger ocular problems. Nevertheless, more studies are necessary to corroborate this hypothesis. PMID
Artigas, José M; Navea, Amparo; García-Domene, M Carmen; Gené, Andrés; Artigas, Cristina
To determine the spectral transmission of contact lenses (CLs), with and without an ultraviolet (UV) filter to evaluate their capacity for protection under UV radiation from artificial illumination (incandescent, fluorescent, xenon (Xe) lamps, or white LEDs (light-emitting diode)). The transmission curves of nine soft CLs were obtained by using a PerkinElmer Lambda 35 UV-vis spectrophotometer. A CIE standard was used for the emission spectra of incandescent and fluorescent lamps, and Xe lamps and white LEDs were measured by using an International Light Technologies ILT-950 spectroradiometer. Five of the nine soft CLs analysed state that they incorporate UV filters, but the other four do not specify anything in this regard. The spectral transmission of all the CLs studied is excellent in the visible region. The CLs with UV filters filter out this radiation more or less effectively. Xe lamps emit a part in the UV region. Incandescent, fluorescent and white LEDs do not emit at all in the UV. Incorporating UV filters is important when the illumination is from a Xe lamp since this light source emits in the UV region. This, however, does not occur with incandescent and fluorescent lamps or white LEDs. The CLs that do incorporate UV filters meet all the standard requirements that the U.S. FDA (Food and Drug Administration) has for UV-blocking CLs Class II (OcularScience, CooperVision and Neolens), and AcuvueMoist and HydronActifresh400 even comply with the stricter Class I. The CLs without UV filters let UVA, UVB and even some UVC through. Copyright © 2015. Published by Elsevier Ltd.
Alvarez-Rivera, Fernando; Concheiro, Angel; Alvarez-Lorenzo, Carmen
Most treatments for diabetic eye conditions rely on systemic (oral) or intravitreal administration, and there is still a demand of efficient and comfortable ocular dosage forms. Our purpose was to design contact lenses (CLs) suitable for local prophylaxis/treatment of diabetes-related ocular pathologies, by means of the incorporation of bioinspired functional groups that can reversibly interact with epalrestat, an aldose reductase inhibitor. Several sets of silicone hydrogels were synthesized varying the contents in 2-hydroxyethyl methacrylate (HEMA), monomethacryloxypropyl-sym-polydimethylsiloxane hydroxypropyl terminated (MCS-MC12), and aminopropyl methacrylamide (APMA). Epalrestat was incorporated before or after polymerization, and loading and release profiles compared. All sets were evaluated regarding optical properties, oxygen permeability, swelling, cytocompatibility, ocular irritation, and corneal drug penetration (using a drug solution as reference). Designed silicone hydrogels showed adequate properties to be used as CLs. Affinity for epalrestat strongly depended on the content in APMA, which endowed the hydrogels with prolonged release in 0.9% NaCl for one week, both after synthesis and after being re-loaded. Bovine corneal permeability tests demonstrated that epalrestat released from the hydrogels can efficiently accumulate into the cornea in spite the concentrations provided on cornea surface were lower than those attained after instillation of concentrated eyedrops. Epalrestat-loaded hydrogels also demonstrated anti-cataract activity in an in vitro model of diabetic eye. Overall, silicone hydrogel CLs functionalized with bioinspired chemical groups represent a first attempt to design CLs adapted to the needs of diabetic eyes, acting as controlled release platforms of epalrestat, promoting drug accumulation and diffusion through cornea. Copyright © 2017 Elsevier B.V. All rights reserved.
Gomes, Thiago Dos Santos; Magnet, Angela; Izquierdo, Fernando; Vaccaro, Lucianna; Redondo, Fernando; Bueno, Sara; Sánchez, Maria Luisa; Angulo, Santiago; Fenoy, Soledad; Hurtado, Carolina; Del Aguila, Carmen
Acanthamoeba keratitis (AK) is a painful and potentially blinding corneal infection caused by Acanthamoeba spp. In Madrid, environmental studies have demonstrated a high presence of these free-living amoebae in tap water. Since most of AK cases occur in contact lenses (CL) wearers with inadequate hygiene habits, the presence of Acanthamoeba in discarded CL has been studied and compared with other common etiological agents of keratitis, such as Pseudomonas aeruginosa and Staphylococcus aureus. One hundred and seventy-seven healthy individuals from Madrid contributed their discarded CL and answered a questionnaire on hygiene habits. DNA was extracted from the CL solution and analyzed by real-time PCR for Acanthamoeba, Pseudomonas aeruginosa and Staphylococcus aureus. These CL and their solutions were also cultured on non-nutrient agar to isolate Acanthamoeba. Among the 177 samples, Acanthamoeba DNA was detected in 87 (49.2%), P. aeruginosa DNA in 14 (7.9%) and S. aureus DNA in 19 (10.7%). Cultivable amoebae, however, were observed in only one sample (0.6%). This isolate was genotyped as T4. The habits reported by this CL owner included some recognized risk factors for AK, but in this study only the practice of "not cleaning the CL case" presented some statistical significant association with Acanthamoeba DNA presence. Detection of the investigated bacterial DNA did not demonstrate statistical significant association with the studied practices, but the presence of P. aeruginosa revealed a possible inhibition of Acanthamoeba in these samples. The PCR results suggest a high presence of Acanthamoeba spp. in healthy CL wearers from Madrid, but we can assume that CL solutions are properly disinfecting the CL since only 1.1% of the positive PCR samples correspond to viable amoebae and, after four years, only one participant reported stronger ocular problems. Nevertheless, more studies are necessary to corroborate this hypothesis.
Compañ, Vicente; Oliveira, Cristina; Aguilella-Arzo, Marcel; Mollá, Sergio; Peixoto-de-Matos, Sofia C; González-Méijome, José M
We defined the theoretical oxygen tension behind modern scleral contact lenses (CLs) made of different rigid gas permeable (RGP) materials, assuming different thickness of the tear layer behind the lens. A second goal was to show clinically the effect of the postlens tear film on corneal swelling. We simulated the partial pressure of oxygen across the cornea behind scleral CLs made of different lens materials (oxygen permeability Dk, 75-200 barrer) and different thickness (Tav, 100-300 μm). Postlens tear film thicknesses (Tpost-tear) ranging from 150 to 350 μm were considered. Eight healthy subjects were fitted randomly with a scleral lens with a thin and a thick postlens tear layer in two different sessions for a period of 3 hours under open-eye conditions. The CLs with less than 125 barrer of Dk and a thickness over 200 μm depleted the oxygen availability at the lens-cornea interface below 55 mm Hg for a postlens tear film of 150 μm. For a postlens tear film thickness of 350 μm, no combination of material or lens thickness will meet the criteria of 55 mm Hg. Our clinical measures of corneal edema showed that this was significantly higher (P < 0.001, Wilcoxon signed ranks test) with the thicker compared to the thinner Tpost-tear (mean ± SD, 1.66 ± 1.12 vs. 4.27 ± 1.19%). Scleral RGP CLs must be comprised of at least 125 barrer of oxygen permeability and up to 200 μm thick to avoid hypoxic effects even under open eye conditions. Postlens tear film layer should be below 150 μm to avoid clinically significant edema. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.
Shi, Dan-Na; Song, Hang; Ding, Tong; Qiu, Wei-Qiang; Wang, Wei
To evaluate the safety of therapeutic bandage contact lens for post-cataract surgery patients and to illustrate its efficacy on post-operative comfort and tear-film stability. A total of 40 participants were recruited and randomly divided into two groups. Group one was instructed to wear bandage contact lenses for a week and use antibiotic eye drops for a month since the first day after surgery. Group two received sub-conjunctival injection of tobramycin and was asked to wear eye pads on the first day after surgery and then were instructed to use antibiotic eye drops as the first group did. Ocular surface disease index (OSDI) questionnaire, slit-lamp microscope examination of tear break-up time (TBUT), corneal fluorescein score (CFS), tear meniscus height (TMH) together with anterior segment optical coherence tomography (AS-OCT) and corneal topography were evaluated preoperatively and postoperatively. The subjective feeling ( P =0.004), TBUT ( P <0.001) and TMH ( P =0.02) post-surgery had improved in patients who used bandage contact lenses compared with those who did not at 1wk post-surgery. Until three month postoperatively, the comfort degree ( P =0.004) and TMH ( P =0.01) of group two were still worse than group one. Moreover, TBUT ( P <0.001) and CFS ( P =0.004) of the group with eye pads got worse than the results before, whereas the group with bandage contact lenses recovered to normal. None of these patients had infections or other complications. Wearing therapeutic bandage contact lens after cataract surgery, compared with traditional eye-pads, is a safe method to improve tear-film stability and reduce post-operative discomfort without hindering corneal incision recovery.
Khater, Mohammad M
The purpose of this study was to evaluate the effect of use of contact lenses to improve visual outcome after repair of traumatic corneal wounds. Two groups of patients (n=30 each) with traumatic full thickness corneal wounds were entered into this study. All cases were caused by sharp objects such as a knife or piece of glass that produced a corneal full thickness wound without any other associated ocular injuries. One group was repaired and received medical treatment (non-contact lens group) and the other group was repaired and a soft contact lens was fitted over the cornea, then medically treated (contact lens group). Each patient was followed up until complete healing, the sutures were removed after about 6 weeks, and the patients were followed up for a further 6 weeks, for a complete follow-up period of 3 months, after which postoperative refraction, manifest refractive spherical equivalent, uncorrected visual acuity, and best-corrected visual acuity were measured and compared between the two groups. After repair and follow-up, uncorrected visual acuity ≥0.3 (decimal system) was achieved in 19 cases (63%) in the contact lens group and in only 14 cases (47%) in the non-contact lens group (P=0.018). Best-corrected visual acuity ≥0.6 was achieved in 26 cases (87%) in the contact lens group and in only 17 cases (57%) in the control group (P=0.012). Soft contact lenses can be used after repair of traumatic corneal wounds to improve visual outcome.
Khater, Mohammad M
Background The purpose of this study was to evaluate the effect of use of contact lenses to improve visual outcome after repair of traumatic corneal wounds. Methods Two groups of patients (n=30 each) with traumatic full thickness corneal wounds were entered into this study. All cases were caused by sharp objects such as a knife or piece of glass that produced a corneal full thickness wound without any other associated ocular injuries. One group was repaired and received medical treatment (non-contact lens group) and the other group was repaired and a soft contact lens was fitted over the cornea, then medically treated (contact lens group). Each patient was followed up until complete healing, the sutures were removed after about 6 weeks, and the patients were followed up for a further 6 weeks, for a complete follow-up period of 3 months, after which postoperative refraction, manifest refractive spherical equivalent, uncorrected visual acuity, and best-corrected visual acuity were measured and compared between the two groups. Results After repair and follow-up, uncorrected visual acuity ≥0.3 (decimal system) was achieved in 19 cases (63%) in the contact lens group and in only 14 cases (47%) in the non-contact lens group (P=0.018). Best-corrected visual acuity ≥0.6 was achieved in 26 cases (87%) in the contact lens group and in only 17 cases (57%) in the control group (P=0.012). Conclusion Soft contact lenses can be used after repair of traumatic corneal wounds to improve visual outcome. PMID:25210430
Beattie, Tara K; Tomlinson, Alan; McFadyen, Angus K; Seal, David V; Grimason, Anthony M
To establish if silicone hydrogel (S-H) contact lenses could be a risk factor for Acanthamoeba infection by facilitating the attachment of trophozoites to their surface and transfer to the cornea and to determine the effect Acanthamoeba culture technique, patient wear, and Pseudomonas biofilm coating have on attachment to the S-H lens. Experimental material study. Attachment to a S-H lens was compared with that of a conventional hydrogel control lens. Sixteen replicates were carried out for both lens types under each test condition. Unworn S-H (PureVision; Bausch & Lomb, Kingston-Upon-Thames UK) and conventional hydrogel (Acuvue; Vistakon, Johnson & Johnson, Jacksonville, FL USA) lens quarters were incubated for 90 minutes in suspensions of liquid or plate-cultured Acanthamoeba castellanii trophozoites. Unworn, worn, and Pseudomonas biofilm coated S-H and hydrogel quarters were incubated for 90 minutes with plate-cultured trophozoites. Trophozoites attached to one surface of each lens quarter were counted by direct light microscopy. Logarithmic transformation of data allowed the use of a parametric analysis of variance. Lens polymer had a significant effect on attachment (P < 0.001), with higher numbers of trophozoites attaching to the S-H lens. Culture technique also had a significant effect on attachment (P = 0.013), with higher numbers of liquid-cultured organisms attaching to both lens types. A significant increase in attachment was demonstrated with worn and Pseudomonas biofilm-coated hydrogel lenses (P < 0.001); however, this difference was not seen with the S-H lens. Acanthamoebal attachment to the S-H lenses was significantly greater than to the conventional hydrogel. Liquid-cultured trophozoites demonstrated a higher affinity for the lenses tested. Wear and bacterial biofilm coating had no effect on attachment to S-H lenses. The increased attachment found with the S-H lens may be an inherent characteristic of the polymer or a side effect of the surface
Almutleb, Essam S; Bradley, Arthur; Jedlicka, Jason; Hassan, Shirin E
This study evaluated the feasibility of using soft contact lenses (CLs) with an opaque centre to induce absolute central scotomas that move with the eye. We examined the geometrical optics prediction that scotoma size will vary with the size of the CL's opaque centre and with ocular pupil size. We also tested the hypothesis that high environmental light levels will ensure that the ocular pupil will remain small enough, even with opaque centre CLs, to generate absolute scotomas representative of those experienced by patients with age-related macular disease. Using an Octopus 900 Perimeter ( www.Haag-Streit.com), kinetic visual fields (VFs) were measured in five normally-sighted subjects using a V4e Goldmann target with CLs that had central opaque areas with diameters of 2.8, 3.0, and 3.2 mm. To control pupil size, VFs were measured with background perimeter bowl luminances of 10, 585, and 1155 cd m-2 . Subjects attempted to (i) fixate the bowl centre; and (ii) place the scotoma edge at the bowl fixation target (eccentric viewing). As predicted, there was a direct relationship between scotoma size and both luminance level and diameter of the opacity. Mean scotoma diameters were 0°, 17.6° and 22°, for the low, medium and high bowl luminances, respectively. Scotoma size was determined primarily by the difference between the diameters of CL opacity and the entrance pupil of the eye and the axial separation between them, and between-subject differences in pupil diameters contributed most to the between-subject variability in scotoma diameter at each light level (SD: 6.01°). Scotoma displacement during eccentric fixation confirmed the gaze-contingent characteristics of this experimental model. It is possible to induce a gaze-contingent absolute scotoma and hence mimic central vision loss using centrally-opaque CLs provided that the CL opacity is larger than the entrance pupil of the eye. This simulation tool will, therefore, be ineffective at low environmental
Allaire, P E; Flack, R D
Hydrodynamic forces occur on lenses due to pressures created in tear films during squeeze motions. Pressures and squeeze forces are calculated for lenses with both flat and steepened base curve radii. A parabolic two-dimensional tear film tickness is assumed for calculation purposes. A tear film with a peripheral film thickness of one-half of the central film thickness produces over three times the squeeze force produced by a constant tear film thickness with the same central clearance. Also, the distance moved by the lens toward the corneal surface is determined.
Altoaimi, Basal H; Kollbaum, Pete; Meyer, Dawn; Bradley, Arthur
Multifocal or multi-zone contact lenses are increasingly being fit to young eyes in an attempt to control myopia progression. However, success in achieving this aim may depend on how much the eye accommodates. The purpose of the current work was to evaluate the ability of an open-field clinical autorefractor to measure on-axis refractive state and accommodation in eyes fit with multifocal contact lenses (CLs). Refractive state was measured with a Grand Seiko WAM-5500 autorefractor (www.grandseiko.com) and a clinical Shack-Hartmann Complete Ophthalmic Analysis System (COAS) aberrometer (www.wfsci.com) in subjects fit bilaterally with single vision aspheric contact lenses, centre distance, and centre near zonal multifocal CLs, and an experimental myopia control multi-zone bifocal CLs (MiSight). Autorefractor measurements were obtained when aligned with the pupil centre, pupil margin, and mid-periphery. Accuracy of refractive state measurements was evaluated using a fully presbyopic (62-year-old) dilated (pupil diameter = 7.1 mm) eye measured through known added spherical powers (trial lenses) of +1.00 D to +6.00 D. Refractive state and accommodation were measured for seven young myopic eyes (23.71 ± 2.87 years) with six target vergences ranging from -0.33 D to -5.00 D. Irrespective of the CL fitted, measured changes in refractive state of the calibration eye were within ≤0.25 D of the added sphere power and the slope (measured refractive state/trial lens power) was approximately -1.0 D/D for both Shack-Hartmann (COAS) aberrometer and Grand Seiko instruments. Also, the Grand Seiko data were highly repeatable (mean measurement standard deviation = 0.04 D) as long as measurements occurred at the same pupil location, but exhibited a hyperopic bias that increased to +1.00 D when eyes were fit with CLs containing significant negative spherical aberration. Centre and marginal refractive states could differ by >3.00 D due to the combined spherical aberration contained in
Eng, W G; Harada, L K; Jagerman, L S
The increasing use of hydrophilic (soft) lenses in the United States hs prompted interest in the clinical investigation of these lenses under various wearing conditions. Any factor causing lens dehydration during wear may affect lens performance and ultimately cause eye discomfort. The purpose of this study was to evaluate the environmental conditions in the aircraft cabin and to observe any changes in the fit of the hydrophilic lenses that might occur during flight. A "laboratory" for testing was set up aboard a World Airways DC-10 on a scheduled round trip between Oakland, California and Honolulu, Hawaii. A keratometer was used to assess lens fit of seven subjects who were wearing hydrophilic lenses. The efficacy of using a soft lens hydrating solution on the fit of the lens was evaluated, but will also be evaluated in a future paper. Atmospheric pressure, humidity, and temperature measurements were recorded throughout the inflight study. The results showed that a decline in cabin humidity from at least 47% to 11% occurred within 30 min of takeoff. Although previous reports have indicated that there are a number of environmental factors in the aircraft that contribute to eye discomfort for lens wearers, this study indicates that low cabin humidity is possibly the most significant factor.
Dixon, Phillip; Chauhan, Anuj
Contact lenses are receiving significant attention for delivering ophthalmic drugs with higher bioavailability compared to eye drops. Here we explore drug transport from delefilcon-A Dailies Total1 ® lenses which are designed to have a thin, high-water content layer on the surface. Our goal is to determine the impact of this high water content layer on drug transport for both hydrophobic (dexamethasone and cyclosporine) and hydrophilic (timolol and levofloxacin) drugs. Drugs were loaded into the lens by soaking in aqueous drug solutions till equilibrium, followed by release in phosphate buffered saline. The concentration data during release was fitted to the diffusion equation without considering the surface layer. If fits were poor, the surface layer was include in the model, as a burst release. Results showed that surface layer resulted in a burst release of about 35% of the loaded drug for the two hydrophilic drugs, and the model did not fit the data unless the surface layer was incorporated as a burst release. For the hydrophobic drugs, there was no burst release and the model fitted the data without including the surface layer likely because of the low partition coefficient of the hydrophobic drugs in the surface layer compared to the lens. The results further confirm the presence of the high water content surface layer on the Dailies Total1 ® lenses. The release profile of the burst release for hydrophilic drugs could be therapeutically useful for antibiotics where a high dose is desirable initially. The effect of vitamin E loading-an established procedure for increasing drug release time in other commercial lenses, was also tested on the release of timolol maleate and levofloxacin. A 20% vitamin E loading was found to increase the release time of timolol and levofloxacin by a factor of 5 and 3-fold respectively, but this increase proved much less effective compared to vitamin E's effect on other commercial silicone hydrogels. Copyright © 2017 Elsevier B
Karaküçük, Sarper; Mirza, G Ertuğrul; Karaküçük, Inci; Akal, Ali; Er, Mustafa
To determine whether nitric oxide (NO) is detectable in the tear fluid of patients with mild forms of papillary conjunctivitis who wear rigid gas-permeable contact lenses. Tear samples were taken from 12 users of rigid gas-permeable contact lenses and 12 healthy controls. Samples were analyzed, and the levels of NO were determined. The mean level of NO in those who wore contact lenses was 118.98 micromol/L (95% CI: 91.85-146.10 micromol/L); whereas the level of NO found in the control subjects was 114.84 micromol/L (95% CI: 102.54-127.14 micromol/L). The difference was statistically insignificant (P>0.05). Nitric oxide levels in the tear fluid of rigid gas-permeable contact lens users did not correlate with the presence of mild symptoms of papillary conjunctivitis.
Sha, Jennifer; Bakaraju, Ravi C; Tilia, Daniel; Chung, Jiyoon; Delaney, Shona; Munro, Anna; Ehrmann, Klaus; Thomas, Varghese; Holden, Brien A
To compare visual acuity (VA), contrast sensitivity, stereopsis, and subjective visual performance of Acuvue® Oasys® for Presbyopia (AOP), Air Optix® Aqua Multifocal (AOMF), and Air Optix® Aqua Single Vision (AOSV) lenses in patients with presbyopia. A single-blinded crossover trial was conducted. Twenty patients with mild presbyopia (add ≤+1.25 D) and 22 with moderate/severe presbyopia (add ≥+1.50 D) who wore lenses bilaterally for 1 h, with a minimum overnight washout period between the use of each lens. Measurements included high- and low-contrast visual acuity (HCVA and LCVA, respectively) at a distance, contrast sensitivity (CS) at a distance, HCVA at intermediate (70 cm) and near (50 cm & 40 cm) distances, stereopsis, and subjective questionnaires regarding vision clarity, ghosting, overall vision satisfaction, and comfort. The test variables were compared among the lens types using repeated-measures ANOVA. Distance variables (HCVA, LCVA, and CS) were significantly worse with multifocal lens than with AOSV lens (p≤0.008), except for AOMF lens in the mild presbyopia group in which no significant difference was observed (p>0.05). Multifocal lenses had significantly greater HCVA at 40 cm than AOSV lens (p≤0.026). AOMF lens had greater intermediate HCVA than AOP lens (p<0.03). AOP lens demonstrated greater improvements in stereopsis than AOMF and AOSV lens in the moderate/severe presbyopia group (p≤0.03). Few significant differences in subjective variables were observed, with no significant difference in the overall vision satisfaction observed between lens types (p>0.05). The proportions of patients willing to buy AOSV, AOMF, and AOP lenses were 20%, 40%, and 50%, respectively, in the mild presbyopia group and 14%, 32%, and 23%, respectively, in the moderate/severe presbyopia group; however, these differences were not statistically significant (p≥0.159). Further development of multifocal lenses is required before significant advantages of
Yañez, Fernando; Concheiro, Angel; Alvarez-Lorenzo, Carmen
Knowledge about the microstructure and the release rate of hydrophilic macromolecules is required for a rational development of comfortable and safe contact lenses. Semi-interpenetrating networks of poly(hydroxyethyl methacrylate) (pHEMA) with poly(vinyl pyrrolidone) (PVP) were prepared by free radical polymerization of HEMA in the presence of PVP K30 or K90F, under anhydrous conditions or after addition of water, and evaluated in terms of swelling, porosity, PVP release rate, air-water surface tension, and friction coefficient. The greater water content was during polymerization, the higher was the swelling degree and porosity. Microphase separation above a certain volume of water resulted in hydrogels with bumpy surface and interconnected pores. All hydrogels showed a high optical clarity and slowly released PVP (20% after 9 days). In general, the greater the content of PVP or the higher its molecular weight was, the lower the friction coefficients were. In the case of hydrogels prepared with water, the friction was influenced by the balance between the ability to hold water in the network (which contributes to the sliding and PVP release) and the deleterious effect of an irregular surface. Controlled delivery of PVP revealed as a critical factor for improving the frictional behavior of pHEMA contact lenses.
Monti, Patrizia; Simoni, Rosa
The role played by water in the molecular structure and properties of commercial soft contact lenses (hydrogels) based on poly 2-hydroxyethyl methacrylate (PHEMA) or poly vinylpyrrolidone (PVP) was investigated by means of vibrational spectroscopy and thermal analyses. The results of this study show that the materials having the greatest water percentage have elastic properties closer to those of the ocular tissues with which they come into contact. Water interacts by hydrogen bonding with the hydrophilic groups present in the polymers, and the strength of this interaction depends on the type of hydrophilic group involved. Moreover, in the case of PVP materials, water also modifies the conformation of the hydrophobic groups. The arrangement of surface water molecules can explain the different adhesion capability of Staphilococcus aureus on this type of lens depending on the water content. In connection with this, a simple model is presented. The water molecules present in the hydrogel structures completely exchange with those of the biological environment. A quantitative analytical method for evaluating the amount of water in commercial lenses by means of Raman spectroscopy is reported.
Schnider, C M
The rigid gas-permeable (RGP) extended-wear lens offers a unique alternative to the hydrogel extended-wear lens as well as to refractive surgery. In suitable patients it can provide almost maintenance-free visual correction for a wide variety of refractive errors. With prudent patient selection, use of high-permeability RGP materials, sound lens design and fitting principles, and conservative follow-up procedures, RGP extended-wear lenses can have success rates exceeding those of either hydrogel extended-wear lenses or refractive surgery, with fewer complications. The complications that do occur are often predictable after a short period of daily wear, and the remainder can often be managed with small changes to lens design.
Li, Shi-Ming; Kang, Meng-Tian; Wu, Shan-Shan; Meng, Bo; Sun, Yun-Yun; Wei, Shi-Fei; Liu, Luoru; Peng, Xiaoxia; Chen, Zhuo; Zhang, Fengju; Wang, Ningli
To evaluate the effect of soft contact lens with concentric ring bifocal and peripheral add multifocal designs on controlling myopia progression in school-aged children. We systematically searched MEDLINE, EMBASE, Cochrane Library and reference lists of included trials. Methodological quality of included trials was assessed using Jadad Scale and Newcastle-Ottawa Quality Assessment Scale items. We identified five randomised controlled trials (RCTs) and three cohort studies with a total of 587 myopic children. Compared with the control group, concentric ring bifocal soft contact lenses showed less myopia progression with a weighted mean difference (WMD) of 0.31 D (95% CI, 0.05~0.57 D, p = 0.02) and less axial elongation with a WMD of -0.12 mm (95% CI, approximately -0.18 to -0.07 mm, p < 0.0001) at 12 months. Relative to the control group, peripheral add multifocal soft contact lenses showed less myopia progression with a WMD of 0.22 D (95% CI 0.14~0.31 D, p < 0.0001) and less axial elongation of -0.10 mm (95% CI -0.13~0.07 mm, p < 0.0001) at 12 months, respectively. The soft contact lenses with concentric ring bifocal and peripheral add multifocal designs produced additional myopia control rates of 30~38% for slowing myopia progression and 31~51% for lessening axial elongation within 24 months. Both concentric ring bifocal and peripheral add multifocal soft contact lenses are clinically effective for controlling myopia in school-aged children, with an overall myopia control rates of 30~50% over 2 years. Concentric ring bifocal soft contact lenses seem to have greater effect than peripheral add multifocal soft contact lenses. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.
Dominguez-Godinez, Carmen Olalla; Martin-Gil, Alba; Carracedo, Gonzalo; Guzman-Aranguez, Ana; González-Méijome, José Manuel; Pintor, Jesús
Purpose To evaluate the possible use of soft contact lenses (CL) to improve the secretagogue role of diadenosine tetraphosphate (Ap4A) promoting tear secretion. Methods Two conventional hydrogel CL (Omafilcon A and Ocufilcon D) and two silicone hydrogel (SiH) CL (Comfilcon A and Balafilcon A) were used. Ap4A was loaded into the lenses by soaking in a 1 mM Ap4A solution during 12 h. In vitro experiments were performed by placing the lenses in multi-wells during 2 h containing 1 ml of ultrapure water. 100 μl aliquots were taken at time zero and every minute for the first 10 min, and then every 15 min. In vivo experiments were performed in New Zealand rabbits and both the dinucleotide release from SiH and tear secretion were measured by means of Schirmer strips and high-pressure liquid chromatography (HPLC) analysis. Results Ap4A in vitro release experiments in hydrogel CL presented a release time 50 (RT50) of 3.9 ± 0.2 min and 3.1 ± 0.1 min for the non-ionic and the ionic CL, respectively. SiH CL released also Ap4A with RT50 values of 5.1 ± 0.1 min for the non-ionic and 2.7 ± 0.1 min for the ionic CL. In vivo experiments with SiH CL showed RT50 values of 9.3 ± 0.2 min and 8.5 ± 0.2 min for the non-ionic and the ionic respectively. The non-ionic lens Ap4A release was able to induce tear secretion above baseline tear levels for almost 360 min. Conclusion The delivery of Ap4A is slower and the effect lasts longer with non-ionic lenses than ionic lenses.
Pescosolido, Nicola; Casciani, Lorena
In this paper, the chemical-physical interactions between two commercially available ophthalmic solutions and hydrogel contact lenses classified according to the four Food and Drug Administration groups were studied by measuring transversal relaxation times (T(2)) of water molecules by low-field nuclear magnetic resonance techniques. The aim was to evaluate possible modifications to the contact lens structure, with particular emphasis on their hydration mechanism. No significant variations in the T(2) values were observed when the T(2) values of the first component of samples swollen with saline solution as the reference were compared with samples of the same set of lenses swollen in the two commercially available ophthalmic solutions. We can, therefore, assume that the hydration characteristics remained unchanged in all the samples studied, and that the experimental ophthalmic solutions ensured an adequate hydration of the sample hydrogel contact lenses without any negative effects on the structure of their polymer chains.
Bietti, G B; De Caro, G; Giraldi, J P; Romani, E
Research has been performed, both experimentally and clinically, to establish the value of the association of soft contact lenses and some types of eye drops. The use of soft contact lenses with eye drops may be useful in some special cases: a) more prolonged and more sustained effect compared with the usual way of administration of eye drops (especially antiglaucomatous substances, antimetabolites, mydriatics); b) possibility of reducing the concentration to avoid local discomfort or systemic side-effects, without loss of their effectiveness on the eye conditions to be treated. The combined use of soft lenses (12.5-15 mm in diameter) with eye drops may be obtained either by presoaking the lens in the liquid or by regular instillation of eye drops after insertion of the lens; the two techniques may of course be associated. In the present research the advantages of utilizing hydrophylic lenses with osmotically active substances, to obtain a better and more protracted dehydration of the cornea, were first examined, in vitro and in vivo. The following substances were tested: 10% propylenglycol, 10% glycerol, 10% glucose and 5% natrium chloride. The clearing effect of the different types of treatment was evaluated in 45 patients with edematous bullous keratopathy with an instrument which measured the infrared light emitted by an optic fiber and reflected by the cornea. The effects were more marked for the epithelial than for the stromal oedema. Another group of investigations was performed with two polypeptides with high molecular weight: Eledoisin, extracted from a mediterranean octopus, Eledone moschata, and Physalaemin, extracted from the skin of a south american batrachian, Physalaemus fuscomaculatus, both of these stimulate the lacrimal secretion and were previously successfully employed topically by the authors against keratoconjunctivitis sicca. The increase of the amount of fluid was however short-lived. Eledoisin at a concentration of 200 mug/ml, was examined
Yildiz Tasci, Yelda; Gürdal, Canan; Sarac, Ozge; Onusever, Aykut
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.
Georges, P; Perrine, D
Because Acanthamoeba keratitis associated with contact lenses were described, several solutions used in stationary eye wash stations were contaminated by free-living amoebae. 0.9% sodium chloride rinsing solutions allowed cyst and trophozoite growth and only one solution for decontamination using hydrogen peroxide led to rapid elimination of cysts and trophozoites. Antiseptic solutions containing ammonium derivatives or chlorhexidine killed only trophozoites. Because of the constant contamination of tap water with Acanthamoeba cysts resistant to chlorine, the prevention of amoebic keratitis in wearers of contact lenses needs: use of sterile solutions for decontamination or rinsing, choice, if possible, of oxidizing solutions, suppression of tap water for rinsing.
Autrata, R; Krejčířová, I; Griščíková, L; Doležel, Z
Our study evaluated the visual and refractive results of LASEK and anterior chamber phakic intraocular lens (pIOL) implantation performed for high myopic anisometropia with amblyopia and contact lens intolerance in children compared with conventional treatment by contact lenses.Fourty-three patients (Group A) aged 3 to 7 years (mean, 5,6 years) with high myopic anisometropia and amblyopia had performed multizonal LASEK (27 eyes) or pIOL Verisyse implantation (16 eyes) on the more myopic eye in general anesthesia. Surgery was followed by patching of the dominant eye. Postoperative visual and refractive outcomes were analyzed and all children had minimally two years follow-up after procedure. Refractive surgical data were reported in standard format to describe safety, efficacy, predictability and stability of the procedure. This Group A of 43 children was compared with control Group B of 37 children (mean age 5,4 years), in whom myopic anisometropia and amblyopia were treated conventionally by contact lenses (CL) and patching of the dominant eye. Visual acuity (VA) and binocular vision (BV) outcome were analyzed and compared in both groups.The mean preoperative spherical equivalent (SE) cycloplegic refraction in Group A was - 9,45 ± 2,47 diopters (D) (range -6.0 to -18.25 D) and the mean postoperative SE -1,48 ± 1,13 D (range + 0,75 to - 2,25 D). The mean preop. decimal uncorrected visual acuity (UCVA) 0,023 ± 0,017 increased to 0,46 ± 0,18. The mean preop.decimal best-corrected visual acuity (BCVA) in Group A was 0,28 ± 0.22 and changed to 0,78± 0,19 by 2 years after surgery. The mean BCVA in Group B was 0,23 ± 0,19, at start of CL correction and amblyopia therapy, and improved to 0,42 ± 0,15 after two years. The mean BCVA at final examination was significantly better in Group A (P < 0,05). Binocular vision improvement expressed by the proportions of subjects gained fusion and stereopsis, was overall better in Group A (81 %) than in Group B (33 %), (P < 0
Kuryan, Jocelyn; Cheema, Anjum; Chuck, Roy S
Near-sightedness, or myopia, is a condition in which light rays entering the eye along the visual axis focus in front of the retina, resulting in blurred vision. Myopia can be treated with spectacles, contact lenses, or refractive surgery. Options for refractive surgery include laser-assisted subepithelial keratectomy (LASEK) and laser-assisted in-situ keratomileusis (LASIK). Both procedures utilize a laser to shape the corneal tissue (front of the eye) to correct refractive error, and both create flaps before laser treatment of corneal stromal tissue. Whereas the flap in LASEK is more superficial and epithelial, in LASIK it is thicker and also includes some anterior stromal tissue. LASEK is considered a surface ablation procedure, much like its predecessor, photorefractive keratectomy (PRK). LASEK was developed as an alternative to PRK to address the issue of pain associated with epithelial debridement used for PRK. Assessing the relative benefits and risks/side effects of LASEK and LASIK warrants a systematic review. To assess the effects of LASEK versus LASIK for correcting myopia. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), which contains the Cochrane Eyes and Vision Trials Register (2016, Issue 10); MEDLINE Ovid (1946 to 24 October 2016); Embase.com (1947 to 24 October 2016); PubMed (1948 to 24 October 2016); LILACS (Latin American and Caribbean Health Sciences Literature Database; 1982 to 24 October 2016); the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), last searched 20 June 2014; ClinicalTrials.gov (www.clinicaltrials.gov); searched 24 October 2016; and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 24 October 2016. We did not use any date or language restrictions in the electronic searches for trials. We considered only randomized controlled trials (RCTs) for the purposes of this review. Eligible RCTs were those in which myopic participants were
Korogiannaki, Myrto; Zhang, Jianfeng; Sheardown, Heather
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
Thurtell, M.J; Dell’Osso, L.F; Leigh, R.J; Matta, M; Jacobs, J.B; Tomsak, R.L
Aim: To determine if acetazolamide, an effective treatment for certain inherited channelopathies, has therapeutic effects on infantile nystagmus syndrome (INS) in a well-studied subject, compare them to other therapies in the same subject and to tenotomy and reattachment (T&R) in other subjects. Methods: Eye-movement data were taken using a high-speed digital video recording system. Nystagmus waveforms were analyzed by applying an eXpanded Nystagmus Acuity Function (NAFX) at different gaze angles and determining the Longest Foveation Domain (LFD). Results: Acetazolamide improved foveation by both a 59.7% increase in the peak value of the NAFX function (from 0.395 to 0.580) and a 70% broadening of the NAFX vs Gaze Angle curve (the LFD increased from 20° to 34°). The resulting U-shaped improvement in the percent NAFX vs Gaze Angle curve, varied from ~60% near the NAFX peak to over 1000% laterally. The therapeutic improvements in NAFX from acetazolamide (similar to T&R) were intermediate between those of soft contact lenses and convergence, the latter was best; for LFD improvements, acetazolamide and contact lenses were equivalent and less effective than convergence. Computer simulations suggested that damping the central oscillation driving INS was insufficient to produce the foveation improvements and increased NAFX values. Conclusion: Acetazolamide resulted in improved-foveation INS waveforms over a broadened range of gaze angles, probably acting at more than one site. This raises the question of whether hereditary INS involves an inherited channelopathy, and whether other agents with known effects on ion channels should be investigated as therapy for this condition. PMID:21270949
Melgosa, M; Hita, E; Velasco, M J
An experimental study of Allergan's Oxysept Comfort system was performed by measuring the slight reddish hue that appears in the disinfecting solution, indicating to the users that their lenses are again ready to be worn. The temporal evolution of the color of the solution has been measured under standardized conditions and analyzed in the CIELAB system, from the perspective of the typical threshold discrimination of the human eye. Color differences between neutralized and non-neutralized solutions occurred in an appropriate direction of the color space to enhance discrimination and were clearly perceptible by normal observers (greater than 9.7 +/- 1.2 CIELAB units). Colorimetric analyses have been used to draw conclusions regarding observers with defective color vision. The color of the solution changes abruptly, approximately 25 min after the neutralization process begins, and remains nearly constant after about 60 min, this agreeing well with the temporal evolution of the hydrogen peroxide concentration.
Zeri, Fabrizio; Calcatelli, Paolo; Donini, Bernardo; Lupelli, Luigi; Zarrilli, Luciana; Swann, Peter G
To assess the accuracy of intraocular pressure (IOP) measurements using rebound tonometry over disposable hydrogel (etafilcon A) and silicone hydrogel (senofilcon A) contact lenses (CLs) of different powers. The experimental group comprised 36 subjects (19 male, 17 female). IOP measurements were undertaken on the subject's right eyes in random order using a rebound tonometer (ICare). The CLs had powers of +2.00D, -2.00D and -6.00D. Six measurements were taken over each contact lens and also before and after the CLs had been worn. A good correlation was found between IOP measurements with and without CLs (all r≥0.80; p<0.05). Bland Altman plots did not show any significant trend in the difference in IOP readings with and without CLs as a function of IOP value. A two-way ANOVA revealed a significant effect of material and power (p<0.01) but no interaction. All the comparisons between the measurements without CLs and with hydrogel CLs were significant (p<0.01). The comparisons with silicone hydrogel CLs were not significant. Rebound tonometry can be reliably performed over silicone hydrogel CLs. With hydrogel CLs, the measurements were lower than those without CLs. However, despite the fact that these differences were statistically significant, their clinical significance was minimal. 2011 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Svitova, Tatyana F.; Lin, Meng C.
Purpose To explore interfacial behaviors and effect of temperature and dilatation on dynamic properties of multilayered human tear lipids extracted from silicone hydrogel (SiH) lenses worn by asymptomatic Asian and Caucasian subjects. Methods Interfacial properties of lipids extracted from Focus® N&D lenses worn by 14 subjects continuously for 1 month were studied. The lipids were deposited on an air bubble immersed in a model tear electrolytes (MTE) solution to form 100 ± 20 nm-thick films. Surface pressure was recorded during slow expansion/contraction cycles to evaluate compressibility and hysteresis of lipid films. Films were also subjected to fast step-strain dilatations at temperatures 22°–45° C for their visco-elastic properties assessment. Results Iso-cycles for Asian and Caucasian lipids were similar at low surface pressures, but had distinctly different compressibility and hysteresis at dynamic pressures exceeding 30 mN/m. Rheological parameters of reconstituted lipids were also dissimilar between Asian and Caucasian. The elastic modulusE∞ for Caucasian lipids was 1.5 times higher than that for Asian lipids, whereas relaxation time (t) was on average 1.3 times higher for Asian. No significant changes were observed in rheological properties of both Asian and Caucasian lipids when temperature increased from 22.0° to 36.5° C. However, for Caucasian lipids, E∞ reduced considerably at temperatures above 42.0° C, while t remained unchanged. For Asian lipids, both E∞ and t started to decline as temperature increased to 38° C and higher. Conclusions Higher elastic modulus of Caucasian lipids and elasticity threshold at certain deformations indicate stronger structure and intermolecular interactions as compared with more viscous Asian lipids. The differences in interfacial behaviors between Asian and Caucasian lipids may be associated with the differences in their chemical compositions. PMID:24270592
Maldonado-Codina, Carole; Efron, Nathan
To investigate the water behavior in hydrogels of differing equilibrium water content (EWC) and to use these results to investigate the opposing discrete model (thermodynamically different classes of water exist in hydrogels) and continuum model (water behaves as a consequence of nonequilibrium conditions) of nonfreezing water in swollen hydrogels. Differential scanning calorimetry (DSC) was used to obtain melting thermograms for five lenses of each of 12 hydrogel lens types. The gravimetric content of the nonfreezing water was subsequently determined from an integrated endotherm for water. The effect of anneal time on the amount of nonfreezing water obtained in samples was investigated before undertaking these measurements. The glass transition temperature (Tg) of each of the lens types was obtained with DSC to investigate how the Tg was related to the amount of nonfreezing water found in the hydrogels. Melting enthalpy increased with increasing anneal time and leveled off at 6 hours. Low-EWC lenses showed endotherms with a single melting peak at 0 degrees C. Materials with a higher EWC showed more complicated melting endotherms, with a broad shoulder occurring at temperatures below 0 degrees C. There was a statistically significant positive correlation between EWC and freezing water (R=0.95, P<0.0001), but the amount of nonfreezing water was similar for all lens materials. There was a statistically significant positive correlation between the Tg of the hydrogels and the theoretically derived weight fraction of nonfreezing water in the hydrogels required to bring the Tg of the gels down to 0 degrees C (R=0.99, P<0.0001) but not with the experimentally derived values (R=0.29, P=0.07). Low-EWC hydrogels have the lowest free-to-bound water ratios. That the experimentally derived values of nonfreezing water are different from the theoretically derived values creates doubt with the continuum model theory. The best model probably employs a combination of the discrete
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
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.
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
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
Guthrie, Sarah E; Jones, Lyndon; Blackie, Caroline A; Korb, Donald R
The purpose of this study was to determine the clinical impact of using SYSTANE BALANCE Lubricant Eye Drops (Alcon, Fort Worth, TX), an oil-in-water emulsion, as a rewetting eye drop in symptomatic contact lens wearers. Subjects who had previously experienced contact lens discomfort (CLD), with a mean lens wearing history of 18.6±12.8 years, were randomly assigned to use a Test (SYSTANE BALANCE Lubricant Eye Drops; n=76) or control (habitual nonlipid contact lens rewetting eye drop; n=30) drop over their contact lenses within 5 min of lens insertion and then subsequently at 2 hr intervals up to a maximum of 4 drops per eye daily for a 1-month period. Assessments of subjective comfort, comfortable wearing time, lid wiper epitheliopathy (LWE), and corneal staining were conducted at baseline and after 1 month, after 6 hr of lens wear. Comfort, wearing time, LWE, and corneal staining all showed statistically significant improvements in the test group using SYSTANE BALANCE Lubricant Eye Drops at the 1-month visit compared with baseline data (all P<0.01) and compared with the control group at the 1-month visit (P<0.01, P=0.01, P<0.01, and P=0.03, respectively). The use of SYSTANE BALANCE Lubricant Eye Drops as a rewetting drop in a group of wearers who experienced symptoms of CLD improved subjective comfort scores, increased comfortable wearing time, and reduced signs of LWE and corneal staining, when compared with the use of non-lipid-containing contact lens rewetting eye drops.
Bendavid, Itai; Avisar, Inbal; Serov Volach, Irena; Sternfeld, Amir; Dan Brazis, Idit; Umar, Lewaa; Yassur, Yiftach; Singer, Pierre; Cohen, Jonathan David
To compare the effectiveness of bandage contact lenses and punctal plugs with ocular lubricants in preventing corneal damage in mechanically ventilated and sedated critically ill patients. Single-center, prospective, randomized, pilot study. Sixteen-bed, general ICU at a tertiary academic medical center. Adults admitted to the ICU and anticipated to require mechanical ventilation and continuous sedation for greater than or equal to 4 days. Patients were randomized to receive eye care with ocular lubricants (n = 38), bandage contact lenses (n = 33), or punctal plugs (n = 33). The bandage contact lenses were changed every 4 days, whereas the punctal plugs remained in situ for the entire study. The primary endpoint was the presence or absence of corneal damage as assessed by the grade of keratopathy. Patients were examined by an ophthalmologist blinded to the study group every 4 days and at the time of withdrawal from the study, due to cessation of sedation, discharge from the ICU, or death. The mean duration of the study was 8.6 ± 6.2 days. The grade of keratopathy in the ocular lubricant group increased significantly in both eyes (p = 0.01 for both eyes) while no worsening was noted in either the lens or punctal plugs groups. In a post hoc analysis of patients with an initially abnormal ophthalmic examination, significant healing of keratopathy was noted in the lens group (p = 0.02 and 0.018 for left and right eyes, respectively) and in the right eye of the plugs group (p = 0.005); no improvement was noted in the ocular lubricant group. Compared with ocular lubrication, bandage contact lenses and punctal plugs were more effective in limiting keratopathy, and their use, particularly of bandage contact lenses, was associated with significant healing of existing lesions.
Dewey, David A.
Laser beam diameters within a schematic human eye are computed for nine different fundus lenses and five different laser delivery systems. These beam diameters taken in conjunction with commonly used power, time, and spot size settings for ophthalmic photocoagulation are used to compare the relative radiant exposure at various structures within the eye. Surprisingly large pupillary radiant exposures result from some combinations of fundus lens, spot size, and laser delivery system. A general guideline for spot size selection is to maintain a pupillary radiant exposure of less than 2 J/mm2. This can be accomplished with parfocal type delivery systems by keeping the product of the selected spot size and the lens's laser magnification under 400 micrometers . With defocus type delivery systems pupillary radiant exposure can be kept below 2 J/mm2, with the exception of the Volk Quadra Aspheric lens, if spot sizes above the 500 micrometers setting are avoided. The Quadra Aspheric lens with both parfocal and defocus delivery systems will maintain less than 2 J/mm2 pupillary radiant exposure if the true retinal spot size is kept below 400 micrometers as with the parfocal systems.
Hall, Brad; Jones, Lyndon; Forrest, James A
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.
Taher, Eman E; Méabed, Eman M H; Abdallah, Islam; Abdel Wahed, Wafaa Y
Acanthamoeba keratitis (AK) is a severe corneal infection that may occur as a serious outcome of improper use of contact lenses (CL). The study aimed to diagnose AK in soft CL users presenting with infectious keratitis, and to identify the prevalent genotypes isolated from different cases. Another aim was to determine the CL hygiene-related risk behaviors, and to explore the risk of water exposure for developing AK. A cross sectional study was performed. A questionnaire was carried out including 260 clinically diagnosed cases as infectious keratitis (170 females and 90 males); all of them were soft CL users for the suspected risk factors. Corneal scrapes from the affected eyes were cultured to diagnose bacterial and AK. PCR was performed and the amplified products were sequenced and compared with GenBank data. The parasite was positively amplified from 32 samples (12.3%). Acanthamoeba T4 genotype was identified in 27/32 (84.4%) of isolates. Other detected genotypes belonged to T5 and T3 genotypes at rates of 9.4%, and 6.25%, respectively. The most important risk factors associated with development of AK were female sex, sleeping while wearing CL, and exposure to water resources through different practices. These practices included rinsing the CL case in tap water, swimming and/or showering while wearing CL, using multipurpose solution for cleaning the lenses, using water from over-building tanks. Rubbing the eyes due to discomfort when applying CL was an additional important risk factor associated with AK. The protective factor was regular hand washing before using CL. CL users were more exposed to AK and should gain enough health education regarding proper lens hygiene and dangers of tap water exposure. Copyright © 2017. Published by Elsevier Ltd.
García-Millán, Eva; Koprivnik, Sandra; Otero-Espinar, Francisco Javier
This paper proposes an approach to improve drug loading capacity and release properties of poly(2-hydroxyethyl methacrylate) (p(HEMA)) soft contact lenses based on the optimization of the hydrogel composition and microstructural modifications using water during the polymerization process. P(HEMA) based soft contact lenses were prepared by thermal or photopolymerization of 2-hydroxyethyl methacrylate (HEMA) solutions containing ethylene glycol di-methacrylate as crosslinker and different proportions of N-vinyl-2-pyrrolidone (NVP) or methacrylic acid (MA) as co-monomers. Transmittance, water uptake, swelling, microstructure, drug absorption isotherms and in vitro release were characterized using triamcinolone acetonide (TA) as model drug. Best drug loading ratios were obtained with lenses containing the highest amount (200 mM) of MA. Incorporation of 40% V/V of water during the polymerization increases the hydrogel porosity giving a better drug loading capacity. In vitro TA release kinetics shows that MA hydrogels released the drug significantly faster than NVP-hydrogels. Drug release was found to be diffusion controlled and kinetics was shown to be reproducible after consecutive drug loading/release processes. Results of p(HEMA) based soft contact lenses copolymerized with ethylene glycol dimethacrylate (EGDMA) and different co-monomers could be a good alternative to optimize the loading and ocular drug delivery of this corticosteroid drug. Copyright © 2015. Published by Elsevier B.V.
Baguet, J; Sommer, F; Duc, T M
Soft contact lens (SCL) surfaces were imaged with atomic force microscopy (AFM). High-resolution images of unworn SCL were obtained under nearly physiological medium. We present images of surfaces of collagen bandage lens under dry or aqueous conditions and of SCL of different water content and fabrication processes. Roughness parameters were determined. AFM studies of surfaces of SCL are expected to provide useful information on the hydrogel surfaces.
Yun, Jun-Won; Hailian, Quan; Na, Yirang; Kang, Byeong-Cheol; Yoon, Jung-Hee; Cho, Eun-Young; Lee, Miri; Kim, Da-Eun; Bae, SeungJin; Seok, Seung Hyeok; Lim, Kyung-Min
In an effort to explore the use of alternative methods to animal testing for the evaluation of the ocular irritancy of medical devices, we evaluated representative contact lenses with the bovine corneal opacity and permeability test (BCOP) and an in vitro eye irritation test using the three-dimensionally-reconstructed human corneal epithelium (RhCE) models, EpiOcular™ and MCTT HCE™. In addition, we compared the obtained results with the ISO standard in vivo rabbit eye irritation test (ISO10993-10). Along with the positive controls (benzalkonium chloride, BAK, 0.02, 0.2, and 1%), the extracts of 4 representative contact lenses (soft, disposable, hard, and colored lenses) and 2 reference lenses (dye-eluting and BAK-coated lenses) were tested. All the lenses, except for the BAK-coated lens, were determined non-irritants in all test methods, while the positive controls yielded relevant results. More importantly, BCOP, EpiOcular™, and MCTT HCE™ yielded a consistent decision for all the tested samples, with the exception of 0.2% BAK in BCOP, for which no prediction could be made. Overall, all the in vitro tests correlated well with the in vivo rabbit eye irritation test, and furthermore, the combination of in vitro tests as a tiered testing strategy was able to produce results similar to those seen in vivo. These observations suggest that such methods can be used as alternative assays to replace the conventional in vivo test method in the evaluation of the ocular irritancy of ophthalmic medical devices, although further study is necessary. Copyright © 2016. Published by Elsevier Ltd.
Chalmers, Robin L; Wagner, Heidi; Kinoshita, Beth; Sorbara, Luigina; Mitchell, G Lynn; Lam, Dawn; Richdale, Kathryn; Zimmerman, Aaron
To compare the habits of United States (US) soft contact lens (SCL) wearers who bought SCLs from their eye care practitioner (ECP), on the internet/telephone, or at retail (not where they were examined) to test the effect of proximity to the prescriber on SCL wear and care practices. Adult SCL wearers completed an adapted Contact Lens Risk Survey (CLRS) online that queried items related to risk factors for SCL-related complications. Responses from subjects who purchased at the ECP, via the internet/telephone, or at a retail store were compared (Chi-Square). Purchase sources were: ECP 646 (67%, 44±12 yrs, 17% male), Retail 104 (11%, 45±13 yrs, 28% male), and Internet/telephone 218 (23%, 45±12 yrs, 18% male); age (p=0.51), gender (p=0.021). Internet purchasers had fewer annual eye exams (79% ECP, 83% retail, 66% internet/telephone, p=0.007), purchased more hydrogel SCLs (34% ECP, 29% retail, 45% internet/telephone, p=0.0034), and paid for SCLs with insurance less often (39% ECP, 29% retail, 19% internet/telephone, p<0.0001). Other behaviors were similar across groups (p>0.05). In this sample, the purchase location of SCL wearers had limited impact on known risk factors for SCL-related complications. Internet purchasers reported less frequent eye exams and were more likely to be wearing hydrogel SCLs. Closer access to the ECP through in-office SCL purchase did not improve SCL habits or reduce the prevalence of risk behaviors. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Kuroda, Kagayaki; Shirakawa, Naoki; Yoshida, Yoshiyuki; Tawara, Kazuya; Kobayashi, Akihiro; Nakai, Toshiharu
We evaluated the magnetization of 21 cosmetic contact lens samples that included various coloring materials with a superconducting quantum interference device with regard to magnetic resonance (MR) safety. We found 7 samples were ferromagnetic; two had both ferromagnetic and diamagnetic properties; and the rest were diamagnetic. The saturated magnetization of the most ferromagnetic sample was 15.0 µJ/T, which yielded a magnetically induced displacement force of 90.0 µN when the spatial gradient of the static magnetic field was 6.0 T/m. The force was less than one-third of the gravitational force.
Arines, Justo; Gargallo, Ana
The training in the use of the slit lamp has always been difficult for students of the degree in Optics and Optometry. Instruments with associated cameras helps a lot in this task, they allow teachers to observe and control if the students evaluate the eye health appropriately, correct use errors and show them how to do it with a visual demonstration. However, these devices are more expensive than those that do not have an integrated camera connected to a display unit. With the aim to improve students' skills in the management of slit lamp, we have adapted USB HD webcams (Microsoft Lifecam HD-5000) to the objectives of the slit lamps available in our contact lenses laboratory room. The webcams are connected to a PC running Linux Ubuntu 11.0; therefore that is a low-cost device. Our experience shows that single method has several advantages. It allows us to take pictures with a good quality of different conditions of the eye health; we can record videos of eye evaluation and make demonstrations of the instrument. Besides it increases the interactions between students because they could see what their colleagues are doing and take conscious of the mistakes, helping and correcting each others. It is a useful tool in the practical exam too. We think that the method supports the training in optometry practice and increase the students' confidence without a huge outlay.
Reza, Syed Azer; Riza, Nabeel A.
To the best of the author's knowledge, demonstrated is the first opto-fluidic technology- based sensor for detection of liquid levels. An opto-fluidic Electronically Controlled Variable Focus Lens (ECVFL) is used to change the spatial intensity profile of the low power optical beam falling on the liquid surface. By observing, tuning and measuring the liquid surface reflected intensity profile to reach its smallest size, the liquid level is determined through a beam spot size versus ECVFL focal length calibration table. Using a 50 μW 632.8 nm laser wavelength liquid illuminating beam, a proof-of-concept sensor is tested using engine oil, vegetable oil, and detergent fluid with measured liquid levels over a 75 cm range. This non-contact Radio Frequency (RF) modulation-free sensor is particularly suited for hazardous fluids in window-accessed sealed containers including liquid carrying vessels in Electromagnetic Interference (EMI) rich environments.
Salopek-Rabatić, Jasminka; Pavan, Josip; Kastelan, Snjezana; Rabatić, Leon
As the number of glaucoma patients rasing up by aging population, importante is, to point out facts about glaucoma patients as contact lens carriers. Diagnostic and therapy options as well as quality of life are discussed and recommended. Glaucoma as chronic desease needs adequate specific diagnostic procedure as a visual field depending on the right/best visual correction, daily therapy, specific eye drop medication, but also needs daily quality of life for those patients. Advantages of both, quality of therapy and quality of life, is explaned and discussed in connection together. It is possible to treat glaucoma patients with the mixture of different active eye drops because of the new glaucoma strategy recently presented, investigated and prescribed as the best therapy approach. The prostaglandines, or the combination of two in one different drugs (combi) bottle is reality. That means, active medication applied once a day, new preservatives strategy from different manufacturers are discussed and recommended.
Reindel, William; Cairns, Gerard; Merchea, Mohinder
Consumer product companies often use in-home studies to gain consumer insights on product performance. Satisfaction surveys completed in the office have been shown to overestimate satisfaction ratings. The purpose of this study was to evaluate the consumer acceptance of a novel multi-purpose solution (Bausch & Lomb Biotrue multi-purpose solution) through the use of a unique Internet survey and a measurement of practitioner satisfaction through in-office evaluations. Contact lens users were converted to an unbranded, investigational-labeled Biotrue multi-purpose solution. Independent practitioners from 15 investigational sites enrolled patients. Following 7 days of use, subjects completed an Internet survey to capture their perspectives regarding the product. After 2 weeks of use, the investigators exited the subjects. Of the 300 subjects enrolled, 291 (97%) completed the Internet survey. Ninety percent rated Biotrue multi-purpose solution "excellent," "very good," or "good" for overall opinion. Significantly more subjects rated Biotrue multi-purpose solution better than their habitual product. Use of Biotrue multi-purpose solution did not affect the fitting characteristics (centration/movement) or surface wetting of the lens. Throughout the evaluation, there were no adverse events reported. Slit lamp examinations revealed that 99.2% of eyes had minimal findings (no findings or trace or mild findings). With 600 eyes enrolled in the study, practitioners agreed that 95.2% of the eyes appeared healthy throughout the study. Use of Internet surveys can be an effective method to gain patient perspectives regarding new products dispensed by eye care practitioners. There was a high level of satisfaction with Biotrue multi-purpose solution. Copyright © 2010 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Diec, Jennie; Naduvilath, Thomas; Tilia, Daniel; Papas, Eric B; Lazon de la Jara, Percy
To describe a ranked symptoms scale (RSS) discriminating subjective responses in contact lens (CL) wear in various situations. Forty experienced clinical trial participants were interviewed for their perceptions of ocular comfort scales, resulting in a numerical RSS. For further evaluation, 20 CL wearers enrolled into a prospective, randomised, crossover trial. Two silicone-hydrogel CLs and a lens care solution (LCS) [Combinations A & B] were selected based on prior performance identifying best/worst combinations for end-of-day comfort. The RSS and a numerical rating scale (NRS) were administered at two time-points (insertion/removal) on alternating days for 6 days. Both NRS and RSS showed acceptable internal consistency for comfort, vision and handling (Cronbach alpha=0.71 for both scales) and similar repeatability for comfort and handling (coefficients-of-repeatability within 0.1 and 0.2 units, respectively, for each scale). The NRS and RSS discriminated differences between combinations for comfort (p≤0.031) and vision (p≤0.026) at both time-points. Additionally, the RSS showed lens/edge awareness influenced discomfort the most, ranking higher at insertion (p=0.038) and higher for Combination-B at both time-points (p≤0.002). Symptoms of dryness and tired eyes increased for both combinations at removal (p<0.02). The RSS also showed haziness and blurred distance vision influenced vision dissatisfaction with Combination-B at lens removal (p≤0.038) while eye strain/headache increased for both combinations by time of removal (p≤0.013). The RSS is able to discriminate subjective responses between combinations and time-of-day. The RSS's ability to rank symptoms may be a useful tool in understanding perceptions of discomfort or dissatisfaction with CL wear. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Sanchez, I; Ortiz-Toquero, S; Blanco, M; Martin, R
Presbyopic contact lens (CL) fittings produce simultaneous vision, providing different retinal images that reduce visual quality and wearers' satisfaction. The purpose of this study was to develop a new method to isolate the multifocality effect of different CL options to manage presbyopia, analysing the impact on binocular visual acuity (VA), stereopsis and contrast sensitivity (CS) and determining the effect of the use of a yellow filter (YF) on visual function. A prospective and double-masked randomized pilot study involving 20 healthy volunteers was conducted. Four multifocal CLs and monovision CLs without far prescription were fitted. All subjects wore their spectacles over the CLs to guarantee optimum VA at distance. Binocular VA, stereopsis and CS were assessed after 20min of CL wear with or without a YF of 455nm. Binocular VA decreased with all multifocal CLs (P<0.05), as did stereopsis (P<0.01). All presbyopia correction reduced CS compared with spectacles (P<0.05), except aspheric designs, at a frequency of 3 cycles/° (P>0.06). Using the YF, visual function improved; better binocular VA was found with all multifocal CLs (statistically significant (P<0.02) with both low-addition designs), and better CS was observed at most spatial frequencies (statistically significant (P<0.02) at low frequencies with all CLs). This pilot study proposes a simple method to analyse the impact of multifocal CL wear on VA, stereopsis and CS while maintaining habitual spectacle correction to assess the patient's short-term opinion and help practitioners and patients make a decision during presbyopia correction with CL fitting. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Rathi, Varsha M; Mandathara, Preeji S; Dumpati, Srikanth
Contact lenses are required for the visual improvement in patients with keratoconus. Various contact lens options, such as rigid gas permeable (RGP) lenses, soft and soft toric lenses, piggy back contact lenses (PBCL), hybrid lenses and scleral lenses are availble. This article discusses about selection of a lens depending on the type of keratoconus and the fitting philosophies of various contact lenses including the starting trial lens. A Medline search was carried out for articles in the English language with the keywords keratoconus and various contact lenses such as Rose k lens, RGP lens, hybrid lens, scleral lens and PBCL. PMID:23925325
Prakash, Mridula; Dhesingh, Ravi Shankaran
Glaucoma, a chronic eye condition caused by progressive degeneration of retinal ganglion cells may result in permanent blindness. The restricted efficiency of currently available glaucoma treatments has awakened a global need for designing a novel anti-glaucoma drug delivery mechanism that targets the drug to the site of action in a sustained manner with less toxicity and side effects. With reference to this global problem in the present study, we have fabricated a biodegradable transparent polymeric material loaded with minimum amount of anti-glaucoma drug, acetazolamide. The drug was modified using a suitable nanocarrier for its sustained drug release. The efficient modification of nanocarrier encapsulated drug as well as the drug loaded polymeric film was studied using various characterization techniques such as UV-visible spectrophotometry, spectroflurimetry, polarizing optical microscope, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), X-ray diffraction (XRD), thermogravimetric analysis and differential scanning calorimetry (TGA/DSC). The characterization techniques indicated efficient transformation of the crystalline drug in to amorphous during nanocarrier encapsulation. The in-vitro drug release study in simulated tear fluid (STF) showed prolonged release of the drug from the nano drug complex for 3 h with the complete degradation of the polymer matrix within 5 min. The fabricated biomaterial showed excellent potential to be developed in to a drug loaded contact lens for sustained glaucoma drug delivery with benefits of low drug content and fewer drug induced side effects. Copyright© Bentham Science Publishers; For any queries, please email at firstname.lastname@example.org.
Zeri, Fabrizio; Durban, Juan J; Hidalgo, Fernando; Gispets, Joan
This two-phase survey aimed to identify the beliefs and attitudes that create a barrier towards contact lens (CL) fitting among adolescents (aged 12-18 years) and their parents attending eye care practitioner clinics in Italy (phase 1) and Iberia (Spain and Portugal; phase 2). In phase 2, the sample was further focused, by limiting it to those adolescents who did not already wear CL. The extent to which CL satisfy aesthetic, visual, and practical needs and their effectiveness, safety, and comfort in the general population and in adolescents was rated by respondents on a 5-point Likert scale. In phase 1, approximately one-third of adolescents (n=146) and parents (n=114) were CL wearers. Most adolescents (77.5% of 223) and parents (66.2% of 230) expressed a high interest in CL use in phase 2 despite none of the adolescents currently wearing CL. Parents, but not adolescents, perceived that CL were significantly less safe in adolescents than in the general population (p<0.05) in phases 1 and 2. Across both phases, adolescents and parents agreed that CL met an aesthetic need in adolescents (p<0.05 versus general population). Among 50% of parents (mainly mothers), significant concerns regarding CL were difficulties following instructions and taking care of the CL and potential eye damage, which, in mothers, led them to show less agreement towards CL use by the adolescent (p<0.001). These findings highlight an essential need for improved education on CL use in the population.
Miñones Conde, M; Conde, O; Trillo, J M; Miñones, J
Mixed monolayers of poly(methyl methacrylate) (PMMA), the main component of hard contact lenses, and dipalmitoyl phosphatidyl choline (DPPC), a characteristic phospholipidic constituent of ocular tear films, were selected as an in vitro model in order to observe the behavior of contact lenses on the eye. Using Langmuir monolayer and Brewster angle microscopy (BAM) techniques, the interaction between both components was analyzed from the data of surface pressure-area isotherms, compressional modulus-surface pressure, and relative film thickness versus time elapsed from the beginning of compression, together with BAM images. Regardless of the surface pressure at which the molecular/monomer areas (A(m)) were recorded, the A(m) mole fractions of PMMA (X(PMMA)) plots show that the experimental results match the theoretical values calculated from additivity rule A(m) = X(PMMA)A(PMMA) + X(DPPC)A(DPPC). The application of the Crisp phase rule to the phase diagram of the PMMA-DPPC system can explain the existence of a mixed monolayer made up of miscible components with ideal behavior at surface pressures below 25 mN/m. However, at very high surface pressures, when collapse is reached (at 60 mN/m), the single collapsed components are segregated into two independent phases. These results allows us to argue that PMMA hard contact lenses in the eye do not alter the structural characteristics of the phospholipid (DPPC) in tears.
Topakova, Anastassia A.; Salmin, Vladimir V.; Gar'kavenko, Victor V.; Levchenko, Julia S.; Lazarenko, Victor I.
Fluorimetry of eye is a perspective technique for research and diagnostics in ophthalmology. It is connected to the structural and functional characteristics of eye that is, actually, the optical system allowing transferring the radiation both for excitation and for registration of fluorescence in different eye's compartments: cornea, lens, vitreous body, and fundus of the eye. At present, different models of ophthalmologic fluorophotometers for the analysis of eye fluorescence as well as more advanced models - scanning fluorophotometers - are offered. Assessment of corneal status in persons wearing contact lenses or in patients with pathological changes (i.e. diabetes mellitus) would give us an opportunity to identify the initial manifestations of corneal pathology at the pre-symptomatic phase. In this paper, we present data on the compact spectrofluorimeter with UV LEDs-induced excitation as well as the method for assessing hypoxic alterations in the eye limb zone caused by contact lenses wearing. We demonstrate dependence of autofluorescence spectra on the contact lenses types and duration of their permanent wearing.
Brennan, Noel A; Coles, M L Chantal; Comstock, Timothy L; Levy, Brian
To evaluate silicone-hydrogel balafilcon A (PureVision, Bausch & Lomb Inc., Rochester, NY) contact lenses worn on a 30-day continuous wear basis when compared with a traditional hydrogel (Acuvue, Vistakon, Johnson and Johnson Vision Products, Inc., Jacksonville, FL) worn on a 7-day extended wear schedule. Prospective, comparative, paired-eye, interventional, multicenter clinical trial. Two hundred twelve ametropes with no significant ocular pathology. Subjects with normal ocular health who conformed to a set of standard criteria were monitored at seven different sites around the globe. Subjects wore both study lenses simultaneously, one on each eye. Lenses were assigned to right and left eyes according to a randomized schedule. The silicone hydrogel was removed and replaced every month and the traditional hydrogel was removed every 7 days and replaced at 14-day intervals. Subjects were followed for up to 1 year with discontinuation on indication divided between lens-related causes, unrelated factors, and loss to follow-up. Discontinuations, symptoms, vision, lens fit, lens surface assessment, slit-lamp assessment, and patient preferences. One hundred twenty three subjects completed the 12-month wearing period. There were no vision-threatening events with either lens type. The silicone-hydrogel lenses showed statistically superior performance in physiologic terms with regard to epithelial microcysts, striae, corneal staining, limbal injection, and bulbar injection. Inflammatory reactions, such as corneal infiltrates and tarsal conjunctival abnormalities occurred at similar rates between the lens types. Visible deposition and postlens debris with associated transient corneal indentation were significantly lower with the traditional hydrogel material at specific time points in the study. Visual acuity was comparable with the two lens types. Subjects rated the silicone-hydrogel material as preferable on subjective scales of dryness, comfort, and lens handling. Overall
Brown, Karl David; Low, Suet; Mariappan, Indumathi; Abberton, Keren Maree; Short, Robert; Zhang, Hong; Maddileti, Savitri; Sangwan, Virender; Steele, David
Extensive damage to the limbal region of the cornea leads to a severe form of corneal blindness termed as limbal stem cell deficiency (LSCD). Whereas most cases of corneal opacity can be treated with full thickness corneal transplants, LSCD requires stem cell transplantation for successful ocular surface reconstruction. Current treatments for LSCD using limbal stem cell transplantation involve the use of murine NIH 3T3 cells and human amniotic membranes as culture substrates, which pose the threat of transmission of animal-derived pathogens and donor tissue-derived cryptic infections. In this study, we aimed to produce surface modified therapeutic contact lenses for the culture and delivery of corneal epithelial cells for the treatment of LSCD. This approach avoids the possibility of suture-related complications and is completely synthetic. We used plasma polymerization to deposit acid functional groups onto the lenses at various concentrations. Each surface was tested for its suitability to promote corneal epithelial cell adhesion, proliferation, retention of stem cells, and differentiation and found that acid-based chemistries promoted better cell adhesion and proliferation. We also found that the lenses coated with a higher percentage of acid functional groups resulted in a higher number of cells transferred onto the corneal wound bed in rabbit models of LSCD. Immunohistochemistry of the recipient cornea confirmed the presence of autologous, transplanted 5-bromo-2′-deoxyuridine (BrdU)-labeled cells. Hematoxylin staining has also revealed the presence of a stratified epithelium at 26 days post-transplantation. This study provides the first evidence for in vivo transfer and survival of cells transplanted from a contact lens to the wounded corneal surface. It also proposes the possibility of using plasma polymer-coated contact lenses with high acid functional groups as substrates for the culture and transfer of limbal cells in the treatment of LSCD. PMID:24328453
Brown, Karl David; Low, Suet; Mariappan, Indumathi; Abberton, Keren Maree; Short, Robert; Zhang, Hong; Maddileti, Savitri; Sangwan, Virender; Steele, David; Daniell, Mark
Extensive damage to the limbal region of the cornea leads to a severe form of corneal blindness termed as limbal stem cell deficiency (LSCD). Whereas most cases of corneal opacity can be treated with full thickness corneal transplants, LSCD requires stem cell transplantation for successful ocular surface reconstruction. Current treatments for LSCD using limbal stem cell transplantation involve the use of murine NIH 3T3 cells and human amniotic membranes as culture substrates, which pose the threat of transmission of animal-derived pathogens and donor tissue-derived cryptic infections. In this study, we aimed to produce surface modified therapeutic contact lenses for the culture and delivery of corneal epithelial cells for the treatment of LSCD. This approach avoids the possibility of suture-related complications and is completely synthetic. We used plasma polymerization to deposit acid functional groups onto the lenses at various concentrations. Each surface was tested for its suitability to promote corneal epithelial cell adhesion, proliferation, retention of stem cells, and differentiation and found that acid-based chemistries promoted better cell adhesion and proliferation. We also found that the lenses coated with a higher percentage of acid functional groups resulted in a higher number of cells transferred onto the corneal wound bed in rabbit models of LSCD. Immunohistochemistry of the recipient cornea confirmed the presence of autologous, transplanted 5-bromo-2'-deoxyuridine (BrdU)-labeled cells. Hematoxylin staining has also revealed the presence of a stratified epithelium at 26 days post-transplantation. This study provides the first evidence for in vivo transfer and survival of cells transplanted from a contact lens to the wounded corneal surface. It also proposes the possibility of using plasma polymer-coated contact lenses with high acid functional groups as substrates for the culture and transfer of limbal cells in the treatment of LSCD.
Theodorou, Maria; Quartilho, Ana; Xing, Wen; Bunce, Catey; Rubin, Gary; Adams, Gillian; Dahlmann-Noor, Annegret
The optimal management of infantile nystagmus syndrome (INS) is still unclear. Contact lenses (CL) may be superior to glasses in improving visual function in INS but it is not known whether their beneficial effects are due to optical correction alone, or to an additional proprioceptive effect, and whether soft CLs would be as effective as rigid CLs. There is little data on feasibility and and the present study aimed to provide this information. We completed a pilot Randomized Control Trial (RCT) at a single tertiary referral centre in London, UK. We enrolled 38 adults with idiopathic INS and randomised them to either plano CL (with corrective spectacles if required) or to corrective CL. CL wear was required for a minimum of 2 weeks. Primary outcome measures were feasibility and safety of CL wear in INS; secondary outcome measures were visual acuity and nystagmus waveform parameters. 27 completed the study (27/38,71%). 4 partcipants withdrew due to difficulty with CL insertion/removal and 7 were lost to follow up. CL tolerability was high (24/27,89%) - 2 found the CLs irritant, and 1 had an exacerbation of allergic eye disease. At two weeks, mean improvement in binocular visual acuity from baseline with plano CLs was 0.07 logMAR (95% confidence interval (CI: 0.03-0.11) and 0.06 logMAR with fully corrective CLs (95% CI:0.02-0.1). Mean improvement in the eXpanded Nystagmus Acuity Function (NAFX, a nystagmus acuity function based on eye movement recording) with plano CLs was -0.04(95% CI: -0.08-0.005) and -0.05 with fully corrective CLs(95% CI: -0.09-0.003). CLs are well tolerated, with a low risk profile. Whilst our study was not powered to detect significant changes in BCVA and waveform parameters between treatment arms, we observed a trend towards an improvement in visual function at two weeks from baseline with CLs.
Nielsen, Kim; Vorum, Henrik; Ehlers, Niels; Aagaard, Nicolaj; Hjortdal, Jesper; Honoré, Bent
Tear film proteins adhere to the surface of contact lenses (CLs). While the proteins in the tears have been extensively studied with various proteomic techniques, adhered proteins to CLs are less studied. In this pilot study, we have separated proteins with 2D gel electrophoresis prior to the conventional mass spectrometry (MS) in order to analyse the deposited proteins on hydrogel CLs from myopic patients. pHEMA and PVA hydrogel CLs worn by 3 patients for different time lengths were analysed. After wear, the CLs were frozen at -20°C. Proteins were extracted in lysis buffer, separated on 12% polyacrylamide gels and silver-stained. Protein spots were excised and identified with liquid chromatography - tandem MS. Deposited proteins were extracted with a yield of 26-66 μg and separated by 2D gel electrophoresis. The silver-stained gels showed similar protein patterns independent of the patient, hydrogel type and wear time. Seventy-two spots were analysed with MS, representing at least 12 different tear film proteins or protein fragments. Deposited tear film proteins from a single set of CLs worn for 1 day can successfully be analysed first with 2D gel electrophoresis and subsequently with MS, thus making examination of individual patients possible. The protein composition appeared homogeneous between the test persons which is a necessity for additional comparison analysis. The molecular masses of the identified proteins indicate that protein degradation occurs only as a minor event. Myopic patients were investigated in this pilot study, but the combined techniques can easily be applied to other eye diseases. © 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.
... 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 ...
Mohammadpour, Mehrdad; Amouzegar, Afsaneh; Hashemi, Hassan; Jabbarvand, Mahmoud; Kordbacheh, Hamed; Rahimi, Firoozeh; Hashemian, Mohammad Naser
To assess the effect of two silicone hydrogel contact lenses with high oxygen permeability in patients having photorefractive keratectomy (PRK). Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran. Sixty patients (120 eyes) who had bilateral PRK were enrolled in this double blind clinical trial. Each patient was fitted with a Lotrafilcon B (Air Optix(®)AQUA, Ciba Vision, Duluth, GA, USA) lens in one eye and a Balafilcon A (PureVision™ Bausch & Lomb, Rochester, NY, USA) lens in the fellow eye. Patients' responses to a subjective questionnaire in terms of pain, foreign body sensation, photophobia, blurred vision and epiphora were evaluated on the first and third postoperative days. Mean pain score for Lotrafilcon B and Balafilcon A contact lenses was 4.43±3.18 vs. 5.45±3.37 on the first postoperative day and 3.43±3.23 vs. 3.88±3.01 on the third postoperative day. However, the difference was only significant in the first 24h after surgery (P=0.032). Foreign body sensation was clinically higher with Balafilcon A contact lens (5.0±3.47 vs. 4.08±3.34 on day 1 and 4.98±3.52 vs. 3.55±3.20 on day 3) and the difference was statistically significant on the first and the third postoperative days (P=0.042 and 0.002, respectively). There was no statistically significant difference between two contact lenses in terms of photophobia, epiphora and blurred vision (P>0.05). The Lotrafilcon B lens resulted in significantly less postoperative pain and discomfort after PRK, especially in the first 24h after PRK. Copyright © 2015. Published by Elsevier Ltd.
González-Méijome, José M; López-Alemany, Antonio; Lira, Madalena; Almeida, José B; Oliveira, M Elisabete C D Real; Parafita, Manuel A
The purpose of the present study was to develop mathematical relationships that allow obtaining equilibrium water content and refractive index of conventional and silicone hydrogel soft contact lenses from refractive index measures obtained with automated refractometry or equilibrium water content measures derived from manual refractometry, respectively. Twelve HEMA-based hydrogels of different hydration and four siloxane-based polymers were assayed. A manual refractometer and a digital refractometer were used. Polynomial models obtained from the sucrose curves of equilibrium water content against refractive index and vice-versa were used either considering the whole range of sucrose concentrations (16-100% equilibrium water content) or a range confined to the equilibrium water content of current soft contact lenses (approximately 20-80% equilibrium water content). Values of equilibrium water content measured with the Atago N-2E and those derived from the refractive index measurement with CLR 12-70 by the applications of sucrose-based models displayed a strong linear correlation (r2 = 0.978). The same correlations were obtained when the models are applied to obtain refractive index values from the Atago N-2E and compared with those (values) given by the CLR 12-70 (r2 = 0.978). No significantly different results are obtained between models derived from the whole range of the sucrose solution or the model limited to the normal range of soft contact lens hydration. Present results will have implications for future experimental and clinical research regarding normal hydration and dehydration experiments with hydrogel polymers, and particularly in the field of contact lenses. 2006 Wiley Periodicals, Inc.
Plainis, Sotiris; Ntzilepis, George; Atchison, David A; Charman, W Neil
To evaluate the effects of the wearer's pupil size and spherical aberration on visual performance with centre-near, aspheric multifocal contact lenses (MFCLs). The advantage of binocular over monocular vision was also investigated. Twelve young volunteers, with an average age of 27 ± 5 years, participated in the study. LogMAR Visual Acuity (VA) was measured under cycloplegia for a range of defocus levels (from +3.0 to -3.0 D, in 0.5 D steps) with no correction and with three aspheric MFCLs (Air Optix Aqua Multifocal) with a centre-near design, providing correction for 'Low', 'Med' and 'High' near demands. Measurements were performed for all combinations of the following conditions: (1) artificial pupils of 6 and 3 mm diameter, (2) binocular and monocular (dominant eye) vision. Depth-of-focus (DOF) was calculated from the VA vs defocus curves. Ocular aberrations under cycloplegia were measured using iTrace. VA at -3.0 D defocus (simulating near performance) was statistically higher for the 3 mm than for the 6 mm pupil (p = 0.006), and for binocular rather than for monocular vision (p < 0.001). Similarly, DOF was better for the 3 mm pupil (p = 0.002) and for binocular viewing conditions (p < 0.001). Both VA at -3.0 D defocus and DOF increased as the 'addition' of the MFCL correction increased. Finally, with the centre-near MFCLs a linear correlation was found between VA at -3.0 D defocus and the wearer's ocular spherical aberration (R(2) = 0.20 p < 0.001 for 6 mm data), with the eyes exhibiting the higher positive spherical aberration experiencing worse VAs. By contrast, no correlation was found between VA and spherical aberration at 0.00 D defocus (distance vision). Both near VA and depth-of-focus improve with these MFCLs, with the effects being more pronounced for small pupils and for binocular rather than monocular vision. Coupling of the wearer's ocular spherical aberration with the aberration profiles provided by MFCLs affects their functionality. Ophthalmic
Bakaraju, Ravi C; Tilia, Daniel; Sha, Jennifer; Diec, Jennie; Chung, Jiyoon; Kho, Danny; Delaney, Shona; Munro, Anna; Thomas, Varghese
To compare the visual performance of prototype contact lenses designed via deliberate manipulation of higher-order spherical aberrations to extend-depth-of-focus with two commercial multifocals, after 1 week of lens wear. In a prospective, participant-masked, cross-over, randomized, 1-week dispensing clinical-trial, 43 presbyopes [age: 42-63 years] each wore AIROPTIX Aqua multifocal (AOMF), ACUVUE OASYS for presbyopia (AOP) and extended-depth-of-focus prototypes (EDOF) appropriate to their add requirements. Measurements comprised high-contrast-visual-acuity (HCVA) at 6m, 70cm, 50cm and 40cm; low-contrast-visual-acuity (LCVA) and contrast-sensitivity (CS) at 6m and stereopsis at 40cm. A self-administered questionnaire on a numeric-rating-scale (1-10) assessed subjective visual performance comprising clarity-of-vision and lack-of-ghosting at various distances during day/night-viewing conditions and overall-vision-satisfaction. EDOF was significantly better than AOMF and AOP for HCVA averaged across distances (p≤0.038); significantly worse than AOMF for LCVA (p=0.021) and significantly worse than AOMF for CS in medium and high add-groups (p=0.006). None of these differences were clinically significant (≤2 letters). EDOF was significantly better than AOMF and AOP for mean stereoacuity (36 and 13 seconds-of-arc, respectively: p≤0.05). For clarity-of-vision, EDOF was significantly better than AOP at all distances and AOMF at intermediate and near (p≤0.028). For lack-of-ghosting averaged across distances, EDOF was significantly better than AOP (p<0.001) but not AOMF (p=0.186). EDOF was significantly better than AOMF and AOP for overall-vision-satisfaction (p≤0.024). EDOF provides better intermediate and near vision performance than either AOMF or AOP with no difference for distance vision after 1 week of lens wear. Copyright © 2017 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.
de Sadeleer, Nicolas
In the light of new case law development, this article examines whether national restrictions on the online sale of pharmaceuticals and medical devices such as contact lenses are consistent either with EU secondary law, either with Article 34 TFEU that prohibits measures having equivalent effect to quantitative restrictions on imports. In particular, this article focuses on an analysis of two judgments on this important issue delivered by the Court of Justice of the European Union in 2003 and 2010, namely the Deutscher Apothekerverband decision and the Ker-Optika decision.
Blümle, S; Kaercher, T; Khaireddin, R
Although contact lenses have long been established in ophthalmology, practical aspects of handling contact lenses is becoming increasingly less important in the clinical training as specialist for ophthalmology. Simultaneously, for many reasons injuries due to wearing contact lenses are increasing. In order to correct this discrepancy, information on contact lenses and practical experience with them must be substantially increased from a medical perspective. This review article deals with the most important aspects for prevention of complications, i.e. contact lens hygiene.
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Dougherty, Paul J
To determine if LASIK using a 130-microm microkeratome head (thin-flap LASIK) is as visually effective and safe as when using a 160-microm head. A study was performed comparing postoperative day 1 uncorrected visual acuity (UCVA) and flap complications in eyes undergoing myopic LASIK with a 130-microm head versus a 160-microm head using the BD K-3000 microkeratome (BD Ophthalmic Systems, Waltham, Mass). The mean preoperative myopia in the 155 eyes of 80 patients in the 130-microm head group was -5.00+/-2.53 diopters (D) compared to -3.78+/-1.73 D in the 279 eyes of 148 patients in the 160-microm head group. The groups were otherwise similar in terms of age, preoperative cylinder, and best spectacle-corrected visual acuity. The geometric mean postoperative day 1 UCVA was 20/25 in the 130-microm head group compared to 20/26 in the 160-microm head group. The only flap complication in the series was a single partial flap in the 160-microm head group. LASIK with a 130-microm head (thin-flap LASIK) is as visually effective and safe as when using a 160-microm head with the BD K-3000 microkeratome.
NETTUNE, GREGORY R.; PFLUGFELDER, STEPHEN C.
Symptoms of tear dysfunction after laser in situ keratomileusis (LASIK) occur in nearly all patients and resolve in the vast majority. Although dry eye complaints are a leading cause of patient discomfort and dissatisfaction after LASIK, the symptoms are not uniform, and the disease is not a single entity. Post-LASIK tear dysfunction syndrome or dry eye is a term used to describe a spectrum of disease encompassing transient or persistent post-operative neurotrophic disease, tear instability, true aqueous tear deficiency, and neuropathic pain states. Neural changes in the cornea and neuropathic causes of ocular surface discomfort may play a separate or synergistic role in the development of symptoms in some patients. Most cases of early post-operative dry eye symptoms resolve with appropriate management, which includes optimizing ocular surface health before and after surgery. Severe symptoms or symptoms persisting after 9 months rarely respond satisfactorily to traditional treatment modalities and require aggressive management. This review covers current theories of post-LASIK dry eye disease, pathophysiology, risk factors, and management options for this disease spectrum of post-LASIK tear dysfunction and neuropathic pain. PMID:20712970
... Consumers Home For Consumers Consumer Updates Focusing on Contact Lens Safety Share Tweet Linkedin Pin it More ... likely to cause substantial consumer injury. Types of Contact Lenses General categories Soft contact lenses. These are ...
Mehta, Prina; Haj-Ahmad, Rita; Al-Kinani, Ali; Arshad, Muhammad Sohail; Chang, Ming-Wei; Alany, Raid G; Ahmad, Zeeshan
Drug-delivery approaches have diversified over the last two decades with the emergence of nanotechnologies, smart polymeric systems and multimodal functionalities. The intended target for specific treatment of disease is the key defining developing parameter. One such area which has undergone significant advancements relates to ocular delivery. This has been expedited by the development of material advancement, mechanistic concepts and through the deployment of advanced process technologies. This review will focus on the developments within lens-based drug delivery while touching on conventional and current methods of topical ocular drug delivery. A summary table will provide quick reference to note the key findings in this area. In addition, the review also elucidates current theranostic and diagnostic approaches based on ocular lenses.
Coskunseven, Efekan; Kymionis, George D; Grentzelos, Michael A; Portaliou, Dimitra M; Kolli, Sai; Jankov, Mirko R
To present visual and refractive outcomes in 11 eyes that underwent femtosecond LASIK and subsequent retreatment with flap lifting using only side cutting. Seven patients (11 eyes) with a mean age of 30.55±5.42 years (range: 24 to 39 years) underwent retreatment 18.18±5.41 months (range: 12 to 26 months) after primary LASIK treatment with side cutting only using a femtosecond laser for the correction of residual refractive error. Mean follow-up after retreatment was 7.72±1.48 months (range: 6 to 10 months). No intra- or postoperative complications were found after LASIK retreatment. Uncorrected distance visual acuity (UDVA) improved in all patients. Mean UDVA improved from 0.54±0.12 (decimal scale) (range: 0.4 to 0.7) preoperatively to 0.99±0.03 (range: 0.9 to 1.0) after retreatment. No patient lost lines of corrected distance visual acuity. Retreatment using a femtosecond laser to create only a side cut is an effective modality to treat residual refractive errors in postoperative LASIK patients. Copyright 2012, SLACK Incorporated.
Phan, Chau-Minh; Bajgrowicz-Cieslak, Magdalena; Subbaraman, Lakshman N.; Jones, Lyndon
Purpose The aim of this study was to evaluate and compare the release of moxifloxacin from a variety of daily disposable (DD) contact lenses (CLs) under various conditions using a novel in vitro eye model. Methods Four commercially available DD conventional hydrogel (CH) CLs (nelfilcon A, omafilcon A, etafilcon A, and ocufilcon B) and three silicone hydrogel (SH) CLs (somofilcon A, narafilcon A, and delefilcon A) were evaluated. These lenses were incubated in moxifloxacin for 24 hours. The release of the drug was measured using a novel in vitro model in three experimental conditions: (1) phosphate buffered saline (PBS); (2) artificial tear solution (ATS) containing a variety of proteins and lipids; and (3) ATS with mechanical rubbing produced by the device. Results Overall, CH CLs had a higher drug release than SH CLs (P < 0.05) under all conditions. Typically, a higher drug release was observed in PBS than ATS (P < 0.05). For CH, drug release was found to be higher in ATS with rubbing than PBS or ATS (P < 0.05). For most lens types, ATS with rubbing produced higher drug release than ATS alone (P < 0.05). Generally, the release kinetics for all conditions were sustained over the 24-hour testing period, and no burst release was observed (P < 0.05). Conclusions Moxifloxacin release from a CL into ATS is lower when compared to release into PBS. When mechanical rubbing is introduced, the amount of drugs released is increased. Translational Relevance Results suggest that sophisticated in vitro models are necessary to adequately model on-eye drug release from CL materials. PMID:27847690
Beruto, D T; Botter, R
This paper illustrates a new thermodynamic and kinetic model that describes the relationship between the water self-diffusion coefficient, D*(w/g), in hydrogel contact lenses, in terms of water matric potential (psi(M)) and equilibrium water content (EWC). Experimental measurements on commercial contact lenses yield water thermodynamic activity values ranging between 0.996 and 0.999. The corresponding psi(M) matric potential is, respectively, between -8 and -2J/mol at temperature 35 degrees C. Comparison between water self-diffusion coefficients derived in this paper and those suggested by other authors shows that our values are greater (25%-50%) than the previous ones. The impact of this model on the nature of the oxygen permeability, pi, in the lenses has been evaluated and the changes of pi with psi(M) and EWC are predicted and compared with direct experimental measurements. For the contact lenses investigated, the oxygen permeability turns out to be only a quadratic function of equilibrium water content, despite the fact that the fraction of the "free" water molecules can be as high as 50%.
Boxer Wachler, Brian S
To compare binocular and monocular vision in patients treated with laser in situ keratomileusis (LASIK) and in non-LASIK patients. Jules Stein Eye Institute, Los Angeles, California, USA. This comparative cross-sectional study comprised 20 postoperative LASIK patients and 20 non-LASIK ametropic patients. LogMAR visual acuity, contrast sensitivity, and infrared pupillometry were tested. Outcome measures were better-eye monocular acuity, binocular acuity, better-eye contrast sensitivity, binocular contrast sensitivity, and pupil diameter under monocular and binocular conditions. Binocular visual acuity and contrast sensitivity were statistically significantly better than the visual acuity in the better eye (P =.0047 to <.0001) in both patient groups. Pupil diameter was statistically significantly smaller under the binocular condition than the monocular condition (P <.0001) in both groups. Monocular testing induced larger pupil diameters, which was associated with reduced vision compared to binocular measurements in LASIK and non-LASIK patients.
Lin, Chien-Hong; Cho, Hsien-Lung; Yeh, Yi-Hsing; Yang, Ming-Chien
The surface wettability and anti-protein adsorption of a silicone-based hydrogel that was synthesized by a block copolymer of polydimethylsiloxane (PDMS) and poly (ethylene glycol) methacrylate (PEGMA) was improved via polyelectrolyte multilayer (PEM) immobilization. Polysaccharide PEMs of chitosan (CS, as a positive-charged agent) and hyaluronic acid (HA, as a negative-charged and anti-adhesive agent) were successfully assembled on the PDMS-PU-PEGMA silicone hydrogel in a layer-by-layer (LBL) self-assembly manner. Atomic force microscopy (AFM) and dyeing data verified the progressive buildup of the PEM silicone hydrogel. The results showed that the contact angle of the silicone hydrogel decreased with an increase in the number of PEM grafting layers. Furthermore, after immobilizing five layers of CS/HA, the protein adsorption decreased from 78 ± 11 to 26 ± 4 μg/cm(2) for HSA and from 55 ± 10 to 20 ± 4 μg/cm(2) for lysozymes. This indicates that CS/HA PEM-immobilized silicone hydrogels can resist protein adsorption. Furthermore, these hydrogels were non-cytotoxic according to an in vitro L929 fibroblast assay. Overall, the results demonstrated that the modified silicone hydrogels exhibited hydrophilicity and anti-protein adsorption, as well as relatively high oxygen permeability and optical transparency. Therefore, they would be applicable as a contact lens material. Copyright © 2015 Elsevier B.V. All rights reserved.
18S ribosomal DNA typing and tracking of Acanthamoeba species isolates from corneal scrape specimens, contact lenses, lens cases, and home water supplies of Acanthamoeba keratitis patients in Hong Kong.
Booton, G C; Kelly, D J; Chu, Y-W; Seal, D V; Houang, E; Lam, D S C; Byers, T J; Fuerst, P A
We examined partial 18S ribosomal DNA (Rns) sequences of Acanthamoeba isolates cultured in a study of microbial keratitis in Hong Kong. Sequence differences were sufficient to distinguish closely related strains and were used to examine links between strains obtained from corneal scrape specimens, contact lenses, lens cases, lens case solutions, and home water-supply faucets of patients with Acanthamoeba. We also looked for evidence of mixed infections. Identification of Acanthamoeba Rns genotypes was based on sequences of approximately 113 bp within the genus-specific amplicon ASA.S1. This permitted genotype identification by using nonaxenic cultures. Of 13 specimens obtained from corneal scrapes, contact lenses, lens cases, or lens case solutions, 12 were Rns genotype T4 and the remaining one was Rns genotype T3. The sequences of corneal scrape specimens of two patients also were the same as those obtained from their contact lenses or lens case specimens. A possible triple-strain infection was indicated by three different T4 sequences in cultures from one patient's lenses. Although faucet water used by patients to clean their lenses is a possible source of infections, specimens isolated from the faucets at two Acanthamoeba keratitis patients' homes differed from their corneal scrape or lens specimens. The overall results demonstrate the potential of this Rns region for tracking Acanthamoeba keratitis strains in infections and for distinguishing single-strain and closely related multiple-strain infections even when other microorganisms might be present with the cultured specimens. They also confirm the predominance of Rns genotype T4 strains in Acanthamoeba keratitis infections.
Pimenta, A F R; Valente, A; Pereira, J M C; Pereira, J C F; Filipe, H P; Mata, J L G; Colaço, R; Saramago, B; Serro, A P
Currently, most in vitro drug release studies for ophthalmic applications are carried out in static sink conditions. Although this procedure is simple and useful to make comparative studies, it does not describe adequately the drug release kinetics in the eye, considering the small tear volume and flow rates found in vivo. In this work, a microfluidic cell was designed and used to mimic the continuous, volumetric flow rate of tear fluid and its low volume. The suitable operation of the cell, in terms of uniformity and symmetry of flux, was proved using a numerical model based in the Navier-Stokes and continuity equations. The release profile of a model system (a hydroxyethyl methacrylate-based hydrogel (HEMA/PVP) for soft contact lenses (SCLs) loaded with diclofenac) obtained with the microfluidic cell was compared with that obtained in static conditions, showing that the kinetics of release in dynamic conditions is slower. The application of the numerical model demonstrated that the designed cell can be used to simulate the drug release in the whole range of the human eye tear film volume and allowed to estimate the drug concentration in the volume of liquid in direct contact with the hydrogel. The knowledge of this concentration, which is significantly different from that measured in the experimental tests during the first hours of release, is critical to predict the toxicity of the drug release system and its in vivo efficacy. In conclusion, the use of the microfluidic cell in conjunction with the numerical model shall be a valuable tool to design and optimize new therapeutic drug-loaded SCLs.
Kammerer, C. C.
Ultrasonic Fresnel lenses are effective focusing elements with potential applications in ultrasonic "contact" testing for defects in materials. Ultrasonic beams focused on concave lenses are used successfully with immersion transducers, for which test object is immersed in water bath. However, for large objects, objects that are already installed, objects on production lines, and objects that can be damaged by water, contact testing is more practical than immersion.
Kumar, Mukesh; Shetty, Rohit; Jayadev, Chaitra; Dutta, Debarun; Nicolsan, Maneck D; Nagaraj, Sriharsha; Kumar, Rajesh S
Objectives: The objective was to determine the repeatability of intraocular pressure (IOP) measurements made through a soft contact lens (CL) using the Scheimpflug noncontact tonometry in healthy subjects. Methods: This prospective, randomized, single-center study included one eye of 88 subjects (40 male and 48 female). Only participants without glaucoma or any other ocular pathology were included in this study. Three consecutive IOP measurements by the Scheimpflug noncontact tonometry were performed with and without daily disposable hydrogel CLs (−0.50 DS) (Dailies-nelfilcon A, 69% water, 8.7 mm base curve, 14 mm diameter, center thickness 0.10 mm) by a single operator. To avoid any bias arising from diurnal variation, all measurements were made at a similar time of day (11 am ± 1 h). The repeatability of IOP measurements using the Scheimpflug noncontact tonometry with and without CLs was evaluated using Pearson's correlation analysis. Bland-Altman plotting was used to assess the limits of agreement between the measurements with and without CLs. Results: The mean (± standard deviation) IOPs with and without CL were 13.80 ± 2.70 and 13.79 ± 2.54 mm of Hg respectively. The mean difference was 0.01 ± 0.16 (95% confidence interval, +1.97 to − 2.00) mm Hg. Statistical analysis via paired t-test showed no statistical difference between the two groups with (P = 0.15). A good correlation was found for IOP measurements with and without CL (r = 0.93, P < 0.001). Good test-retest reliability was found when IOP was measured with and without CL. Conclusion: There was no significant difference between IOP measured with and without CLs by Scheimpflug noncontact tonometry. PMID:26044471
... For Consumers Consumer Information by Audience For Women Contact Lens Care Share Tweet Linkedin Pin it More ... 1088, www.fda.gov/medwatch Learn More about Contact Lens Care Other Tips on Contact Lenses Decorative ...
Parkhurst, Gregory D
The aim of this study was to evaluate and compare night vision and low-luminance contrast sensitivity (CS) in patients undergoing implantation of phakic collamer lenses or wavefront-optimized laser-assisted in situ keratomileusis (LASIK). This is a nonrandomized, prospective study, in which 48 military personnel were recruited. Rabin Super Vision Test was used to compare the visual acuity and CS of Visian implantable collamer lens (ICL) and LASIK groups under normal and low light conditions, using a filter for simulated vision through night vision goggles. Preoperative mean spherical equivalent was -6.10 D in the ICL group and -6.04 D in the LASIK group (P=0.863). Three months postoperatively, super vision acuity (SVa), super vision acuity with (low-luminance) goggles (SVaG), super vision contrast (SVc), and super vision contrast with (low luminance) goggles (SVcG) significantly improved in the ICL and LASIK groups (P<0.001). Mean improvement in SVaG at 3 months postoperatively was statistically significantly greater in the ICL group than in the LASIK group (mean change [logarithm of the minimum angle of resolution, LogMAR]: ICL =-0.134, LASIK =-0.085; P=0.032). Mean improvements in SVc and SVcG were also statistically significantly greater in the ICL group than in the LASIK group (SVc mean change [logarithm of the CS, LogCS]: ICL =0.356, LASIK =0.209; P=0.018 and SVcG mean change [LogCS]: ICL =0.390, LASIK =0.259; P=0.024). Mean improvement in SVa at 3 months was comparable in both groups (P=0.154). Simulated night vision improved with both ICL implantation and wavefront-optimized LASIK, but improvements were significantly greater with ICLs. These differences may be important in a military setting and may also affect satisfaction with civilian vision correction.
Jacobson, Steven D.
Certain examples provide optical contact micrometers and methods of use. An example optical contact micrometer includes a pair of opposable lenses to receive an object and immobilize the object in a position. The example optical contact micrometer includes a pair of opposable mirrors positioned with respect to the pair of lenses to facilitate viewing of the object through the lenses. The example optical contact micrometer includes a microscope to facilitate viewing of the object through the lenses via the mirrors; and an interferometer to obtain one or more measurements of the object.
... disap- pointed. Everyone develops the need to wear reading glasses in their 40s or 50s due to ... corrected for distance with LASIK, you will need reading glasses to correct for presbyopia once it has ...
Bakaraju, Ravi C; Ehrmann, Klaus; Ho, Arthur
To compare the computed optical performance of prototype lenses designed using deliberate manipulation of higher-order spherical aberrations to extend depth-of-focus (EDOF) with two commercial multifocals. Emmetropic, presbyopic, schematic eyes were coupled with prototype EDOF and commercial multifocal lenses (Acuvue Oasys for presbyopia, AOP, Johnson & Johnson & Air Optix Aqua multifocal, AOMF, Alcon). For each test configuration, the through-focus retinal image quality (TFRIQ) values were computed over 21 vergences, ranging from -0.50 to 2.00D, in 0.125D steps. Analysis was performed considering eyes with three different inherent aberration profiles: five different pupils and five different lens decentration levels. Except the LOW design, the AOP lenses offered 'bifocal' like TFRIQ performance. Lens performance was relatively independent to pupil and aberrations but not centration. Contrastingly, AOMF demonstrated distance centric performance, most dominant in LOW followed by MED and HIGH designs. AOMF lenses were the most sensitive to pupil, aberrations and centration. The prototypes demonstrated a 'lift-off' in the TFRIQ performance, particularly at intermediate and near, without trading performance at distance. When compared with AOP and AOMF, EDOF lenses demonstrated reduced sensitivity to pupil, aberrations and centration. With the through focus retinal image quality as the gauge of optical performance, we demonstrated that the prototype EDOF designs were less susceptible to variations in pupil, inherent ocular aberrations and decentration, compared to the commercial designs. To ascertain whether these incremental improvements translate to a clinically palpable outcome requires investigation through human trials. Copyright © 2017 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.
Beach, Raymond J. , Benett
A lensing duct to condense (intensify) light using a combination of front surface lensing and reflective waveguiding. The duct tapers down from a wide input side to a narrow output side, with the input side being lens-shaped and coated with an antireflective coating for more efficient transmission into the duct. The four side surfaces are uncoated, preventing light from escaping by total internal reflection as it travels along the duct (reflective waveguiding). The duct has various applications for intensifying light, such as in the coupling of diode array pump light to solid state lasing materials, and can be fabricated from inexpensive glass and plastic.
Beach, R.J.; Benett, W.J.
A lensing duct to condense (intensify) light using a combination of front surface lensing and reflective waveguiding is described. The duct tapers down from a wide input side to a narrow output side, with the input side being lens-shaped and coated with an antireflective coating for more efficient transmission into the duct. The four side surfaces are uncoated, preventing light from escaping by total internal reflection as it travels along the duct (reflective waveguiding). The duct has various applications for intensifying light, such as in the coupling of diode array pump light to solid state lasing materials, and can be fabricated from inexpensive glass and plastic. 3 figures.
Bakaraju, Ravi C; Fedtke, Cathleen; Ehrmann, Klaus; Ho, Arthur
To compare the contributions of single vision (SVCL) and multifocal contact lenses (MFCL) to the relative peripheral refraction (RPR) profiles obtained via an autorefractor and an aberrometer in a pilot study. Two instruments, Shin-Nippon NVision K5001 (SN) and COAS-HD, were modified to permit open field PR measurements. Two myopic adults (CF, RB) were refracted (cycloplegia) under eight conditions: baseline (no CL); three SVCLs: Focus Dailies(®) (Alcon, USA), PureVision(®) (Bausch & Lomb, USA) and AirOptix(®) (Alcon, USA); and four MFCLs: AirOptix(®) (Alcon, USA), Proclear(®) Distant and Near (Cooper Vision, USA), and PureVision(®) (Bausch & Lomb, USA). CLs had a distance prescription of -2.00D and for MFCLs, a +2.50D Add was selected. Five independent measurements were performed at field angles from -40° to +40° in 10° increments with both instruments. The COAS-HD measures were analyzed at 3mm pupil diameter. Results are reported as a change in the relative PR profile, as refractive power vector components: M, J180, and J45. Overall, at baseline, M, J180 and J45 measures obtained with SN and COAS-HD were considerably different only for field angles ≥±30°, which agreed well with previous studies. With respect to M, this observation held true for most SVCLs with a few exceptions. The J180 measures obtained with COAS-HD were considerably greater in magnitude than those acquired with SN. For SVCLs, the greatest difference was found at -40° for AirOptix SV (ΔCF=3.20D, ΔRB=1.56D) and for MFCLs it was for Proclear Distance at -40° (ΔCF=2.58D, ΔRB=1.39D). The J45 measures obtained with SN were noticeably different to the respective measures with COAS-HD, both in magnitude and sign. The greatest difference was found with AirOptix Multifocal in subject RB at -40°, where the COAS-HD measurement was 1.50D more positive. In some cases, the difference in the RPR profiles observed between subjects appeared to be associated with CL decentration. For most test
Limon, Ofer; Zalevsky, Zeev
The halo effect is a very problematic visual artifact occurring in extended depth of focus or multi-focal ophthalmic lenses such as e.g. intra-ocular (after cataract surgery) or contact lenses when used in dark illumination conditions. This artifact is generated due to surface structures added on top of those lenses in order to increase their depth of focus or to realize multiple focal lengths. In this paper we present novel solution that can resolve this major problem of ophthalmic lenses. The proposed solution involves modification to the surface structure that realizes the extended depth of focus. Our solution is fabricated and numerically and experimentally validated also in preliminary in-vivo trials.
Wachler, Brian S Boxer; Hiatt, Drew; Chou, Brian; Christie, Jonathan P
To evaluate the amount of miosis induced by over-minused lenses and to assess subjective reduction of halos following laser in situ keratomileusis (LASIK) with such lenses. Part I: Infrared pupil diameter was assessed in 14 patients who had not had ocular surgery. The accommodative/miotic reflex was stimulated with concave trial lenses in -1.00-D increments up to -4.00 D while viewing the 20/40 acuity line. Part II. Subjective halos around a distant light were assessed in 14 patients following LASIK for myopia, with and without a -1.00-D lens over manifest refraction. Part I: 100%, 79%, and 64% of patients clearly saw the 20/40 line with a -1.00-D lens, -2.00-D lens, and -3.00/-4.00-D lens, respectively. Mean pupil diameter decreased by 0.2 mm with the -1.00-D lens (P = .02), 0.5 mm with the -2.00-D lens (P = .003), 0.9 mm with the -3.00-D lens (P = .008,), and 1.1 mm with the -4.00-D lens (P = .008). Part II: 11 of 14 patients (79%) noticed a decrease in the size of the halo (30% average reduction) when over-minused by -1.00 D. Pupil diameters and halos decreased with a -1.00-D overcorrection in patients following LASIK. Patients with pupil-dependent night halos after LASIK may benefit from mildly over-minused lenses.
In a long line of intellectual triumphs, Einstein’s theory of general relativity was his greatest and most imaginative. It tells us that what we experience as gravity can be most accurately described as the bending of space itself. This idea leads to consequences, including gravitational lensing, which is caused by light traveling in this curved space. This is works in a way analogous to a lens (and hence the name). In this video, Fermilab’s Dr. Don Lincoln explains a little general relativity, a little gravitational lensing, and tells us how this phenomenon allows us to map out the matter ofmore » the entire universe, including the otherwise-invisible dark matter.« less
In a long line of intellectual triumphs, Einsteinâs theory of general relativity was his greatest and most imaginative. It tells us that what we experience as gravity can be most accurately described as the bending of space itself. This idea leads to consequences, including gravitational lensing, which is caused by light traveling in this curved space. This is works in a way analogous to a lens (and hence the name). In this video, Fermilabâs Dr. Don Lincoln explains a little general relativity, a little gravitational lensing, and tells us how this phenomenon allows us to map out the matter of the entire universe, including the otherwise-invisible dark matter.
In a long line of intellectual triumphs, Einstein’s theory of general relativity was his greatest and most imaginative. It tells us that what we experience as gravity can be most accurately described as the bending of space itself. This idea leads to consequences, including gravitational lensing, which is caused by light traveling in this curved space. This is works in a way analogous to a lens (and hence the name). In this video, Fermilab’s Dr. Don Lincoln explains a little general relativity, a little gravitational lensing, and tells us how this phenomenon allows us to map out the matter of the entire universe, including the otherwise-invisible dark matter.
Executive Summary Objective The objective of this analysis is to review the effectiveness, safety, and cost-effectiveness of phakic intraocular lenses (pIOLs) for the treatment of myopia, hyperopia, and astigmatism. Clinical Need: Condition and Target Population Refractive Errors Refractive errors occur when the eye cannot focus light properly. In myopia (near- or short-sightedness), distant objects appear blurry because the axis of the eye is too long or the cornea is too steep, so light becomes focused in front of the retina. Hyperopia (far sightedness) occurs when light is focused behind the retina causing nearby objects to appear blurry. In astigmatism, blurred or distorted vision occurs when light is focused at two points rather than one due to an irregularly shaped cornea or lens. Refractive errors are common worldwide, but high refractive errors are less common. In the United States, the prevalence of high myopia (≤ −5 D) in people aged 20 to 39, 40 to 59, and 60 years and older is 7.4% (95% confidence interval [CI], 6.5% – 8.3%), 7.8% (95% CI, 6.4% – 8.6%), and 3.1% (95% CI, 2.2% – 3.9%), respectively. The prevalence of high hyperopia (≥ 3 D) is 1.0% (95% CI, .6% – 1.4%), 2.4% (95% CI, 1.7% – 3.0%), and 10.0% (95% CI, 9.1% – 10.9%) for the same age groupings. Finally, the prevalence of astigmatism (≥ 1 D cylinder) is 23.1% (95% CI, 21.6% – 24.5%), 27.6% (95% CI, 25.8% – 29.3%) and 50.1% (48.2% – 52.0%). Low Vision According to the Ontario Schedule of Benefits, low visual acuity is defined by a best spectacle corrected visual acuity (BSCVA) of 20/50 (6/15) or less in the better eye and not amenable to further medical and/or surgical treatment. Similarly, the Ontario Assistive Devices Program defines low vision as BSCVA in the better eye in the range of 20/70 or less that cannot be corrected medically, surgically, or with ordinary eyeglasses or contact lenses. Estimates of the prevalence of low vision vary. Using the criteria of
... Implants and Prosthetics Phakic Intraocular Lenses Phakic Intraocular Lenses Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print Phakic intraocular lenses are new devices used to correct nearsightedness. These ...
Barnett, Melissa; Lien, Vivian; Li, Jennifer Y; Durbin-Johnson, Blythe; Mannis, Mark J
To examine the clinical outcomes of scleral lenses for visual rehabilitation after penetrating keratoplasty (PK). A retrospective review was conducted for 34 patients (48 eyes) who had a history of prior PK and were fit with scleral lenses between October 2009 and December 2013 at the UC Davis Eye Center. The most common initial indication for PK was keratoconus in 27 eyes (56%). Thirty-three eyes (69%) had previously been fit with other types of contact lenses, with small-diameter rigid gas-permeable lenses being the most common. The improvement in best-corrected visual acuity with a scleral lens compared with prior spectacle refraction or other contact lens was a mean of two best-corrected visual acuity lines. Forty-four eyes (91.7%) achieved functional vision with best scleral lens-corrected visual acuities of 20/40 or better. Patients who continued wearing scleral lenses were significantly more likely to report "good" subjective vision compared with patients who abandoned scleral lens wear (P=0.009), although change in objective best-corrected visual acuity did not differ significantly. There were no cases of infectious keratitis. Six eyes (12.5%) developed graft rejection; 3 were able to resume scleral lens wear. Nineteen eyes (39.5%) discontinued scleral lens wear for various reasons, the most common reason for discontinuation of lens wear was difficulty with scleral lens insertion or removal (8 eyes, 42.1%). Scleral lenses are effective and safe in patients who have had PK. There was a mean gain in visual acuity, with the majority of patients achieving 20/40 vision or better. The patient's subjective perception of vision was a significant factor in determining whether scleral lens wear was continued or abandoned.
Saeed, Ahmed M; Abdrabbo, Mohamed A
Purpose To assess the safety and efficacy of laser-assisted in situ keratomileusis (LASIK) in facilitating strabismus management in noncompliant children with fully accommodative esotropia. Setting Ebsar Eye Center, Benha University (Benha, Egypt). Methods The study comprised 20 eyes of ten consecutive patients with accommodative esotropia. All patients were noncompliant with glasses and had refractive stability. They received brief general anesthesia and had bilateral LASIK using Wavelight® Algretto Wave® Eye-Q Excimer Laser (Alcon, Inc, Hunenberg, Switzerland) to fully correct their hyperopic refractive errors aiming to achieve orthophoria. Preoperative and postoperative best corrected visual acuity, cycloplegic refraction, angle of squint, and any LASIK complications were recorded. Follow-up period was 9 months. Results The age of patients ranged 5.1–9.2 years and the hyperopic error range was +3.5 D to +6.75 D, with anisometropia 2 D or less. No patient had decreased best corrected visual acuity or loss of fusion ability. The postoperative refractive error ranged from −0.75 D to +1.5 D at the end of the study period. All patients achieved orthophoria. No significant intraoperative or postoperative complications were recorded. Conclusion LASIK appears to be effective and relatively safe to treat accommodative esotropic children by reducing their hyperopic refractive error, however, patient selection is critical. Larger studies with longer follow-up are necessary to determine its long-term effects. PMID:22267914
Willcox, Mark D P
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.
Foulks, Gary N
To summarize the present status of safety and efficacy of contact lens wear. Literature review. Ovid Medline searches were performed on records from 1966 through 2005 using keywords: keratitis, contact lens complications, extended-wear contact lenses, and silicone-hydrogel contact lenses. Patients desire comfort, clarity of vision, and prolonged contact lens wear when contact lenses are used to correct refractive error. Practitioners desire patient satisfaction but also require maintenance of the integrity of the eye and no complications that jeopardize vision or health of the eye. Improvements in the oxygen permeability of the contact lens materials, design of the contact lens and its surface, and solutions for the maintenance of the lens have reduced but not eliminated the risks of infection, inflammation, and conjunctival papillary reaction associated with contact lens wear. The lessons of past and recent history suggest that patient education and practitioner participation in the management of contact lens wear continue to be critical factors for patient satisfaction and safety in the extended wear of contact lenses. The availability of highly oxygen permeable contact lenses has increased the tolerance and safety of extended contact lens wear, but patient instruction and education in proper use and care of lenses is required and caution is advised.
Mastropasqua, Leonardo; Calienno, Roberta; Lanzini, Manuela; Salgari, Niccolò; De Vecchi, Sergio; Mastropasqua, Rodolfo; Nubile, Mario
The purpose of this study was to evaluate the incidence of opaque bubble layer (OBL) in femtosecond laser-assisted in situ keratomileusis (LASIK) flaps created with the support of Visumax Carl Zeiss femtosecond laser, planned with different flap diameters (7.90, 8.0, and 8.20 mm) and the same laser energy and power settings. Incidence of intraoperative OBL in flaps of consecutive 108 patients (216 eyes) subjected to bilateral femtosecond-assisted LASIK was considered. Flap creation was performed with the same laser design parameters (spot distance and energy offset) and different presetting diameters of 7.90 mm (72 eyes, group 1), 8 mm (72 eyes, group 2), and 8.20 mm (72 eyes, group 3). The incidence of OBL was considered and its extension was reported measuring involvement of different four corneal flap quadrants in which was theoretically divided the entire flap area; based on these data, OBL presence was classified as none (no evidence of OBL), minimal (minimal presence in not more that one quadrants corneal flap), mild (OBL presence in almost two or three quadrants without tendency to invade central cornea), and moderate (OBL presence in almost three quadrants with tendency to invade central cornea). In group 1, the incidence of OBL was of 23.6 % (17 eyes) with a mild/moderate presence; in group 2, incidence was 20.8 % (15 eyes) with mild presence. Group 3 presented a reduced OBL incidence (4.1 %, 3 eye) with a minimal presence. No statistically significant difference was found between group 1 and 2 (p = 0.8414).We found statistically significant differences between group 1 and group 3 (p = 0.0012) and between groups 2 and 3 (p = 0.0044). A significant reduction and extension of OBL incidence were evident when LASIK flap settings diameter was increased, and flap edge was closer to the contact glass border; this is probably consequent to a more effective gas dispersion outside of corneal flap.
Abrieu-Lacaille, M; Saib, N; Rambaud, C; Berguiga, M; Fenolland, J-R; Bonnel, S; Crepy, P; Froussart-Maille, F; Rigal-Sastourne, J-C
To evaluate efficacy and patient satisfaction of presbyopic hyperopes treated with centered PresbyLASIK (multifocality centered on near vision) by the SUPRACOR technique (Technolas Perfect Vision). This is a retrospective study carried out at Percy Army Teaching Hospital from September 2011 through September 2013. Fifty-nine eyes of 29 patients were included and underwent PresbyLASIK. Study parameters included uncorrected binocular distance (DVA) and near (NVA) visual acuity, aberrometry, central corneal curvature by corneal topography (bump), and patient satisfaction (questionnaire). Mean uncorrected binocular visual acuity was found to be 0.09 logmar for DVA and 0.22 for NVA on post-operative day one, 0.04 logmar for DVA and 0.17 for NVA at 1 month post-operatively, 0.15 logmar for DVA and 0.19 for NVA at 3 months post-operatively, and -0.02 logmar for DVA and 0.18 for NVA at 6 months post-operatively. Mean central corneal curvature was found to be 2.56±0.9 diopters. There were significantly more higher-order aberrations in the central 5mm post-operatively (P<0.01). Among the patients undergoing bilateral SUPRACOR LASIK, 79% were entirely satisfied with the surgery, and all patients would recommend the procedure to their family and friends. Eighty-six percent of these patients acheived total spectacle independence at distance and near. SUPRACOR PresbyLASIK is a method of choice in overcoming spectacle dependence in presbyopic hyperopes. Copyright © 2014. Published by Elsevier Masson SAS.
Cosar, C B; Rapuano, C J; Cohen, E J; Laibson, P R
To describe a post-LASIK patient with decreased vision and a chalazion of the upper eyelid. A 46-year-old man was referred with decreased vision of 1 month's duration. He underwent bilateral uncomplicated LASIK for myopic astigmatism 1.5 years and bilateral enhancements 1 year previously. He had 20/20 uncorrected vision in both eyes after those procedures. He developed a chalazion of his right central upper eyelid 1 month prior with simultaneous blurring of vision. On our examination, his uncorrected visual acuity was 20/60 in the right eye. Complete eye examination including refraction, computerized corneal topography, and pachymetry were done. With a manifest refraction of +1.25 +0.50x80, the visual acuity in the right eye improved to 20/20. Computerized corneal topography revealed circular central corneal flattening in both eyes, much greater in the right eye than the left eye. The location of the chalazion with the right eye closed corresponded to the area of central corneal flattening. The central power from the corneal topography was 39.4 D OD and 40.8 D OS. He was diagnosed as having acquired hyperopia associated with chalazion-induced central corneal flattening of the right eye. Chalazion-induced hyperopic change on topography disappeared, and his uncorrected vision improved to 20/20 in the left eye as the chalazion resolved completely. In post-LASIK patients with decreased vision and topography changes late after surgery, periocular masses should be considered in the differential diagnosis. Decreased corneal thickness and rigidity after LASIK might be a predisposing factor to external compression-induced curvature changes.
Knorz, M C; Hugger, P; Jendritzka, B; Liermann, A
Data on mesopic vision after LASIK are not available to date. We therefore evaluated mesopic vision in myopic eyes before and after LASIK. Sixty-seven eyes (34 patients) treated using the Automatic Corneal Shaper and the Keracor 117CT spot-scanning excimer laser were included. All eyes had best-corrected vision of 20/25 or better preoperatively. We measured spectacle refraction, visual acuity, and mesopic vision without and with glare (Nyktometer, Rodenstock) both preoperatively and 1 year after LASIK. Results were evaluated in three groups with reference to baseline refraction, and numbers of patients who saw a contrast of 1:5 or less were compared. Myopia -1 to -5 D (group 1; n = 26): Preoperatively (postoperatively), 89% (96%) (P = 0.03) of eyes identified a contrast of 1:5 or less without glare, while 65% (73%) achieved that level with glare. Myopia -5.1 to -10 D (group 2; n = 24): Preoperatively (postoperatively), 83% (75%) of eyes identified a contrast of 1:5 or less without glare, while 50% (21%) achieved that level with glare. Myopia -10.1 to -15 D (group 3; n = 11): Preoperatively (postoperatively), 73% (55%) of eyes identified a contrast of 1:5 or less without glare, while 46% (27%) achieved that level with glare. LASIK seems to cause a reduction of mesopic vision under glare conditions in corrections of more than -5 D. In corrections of more than -10 D, mesopic vision without glare is reduced, too. However, differences were not statistically significant when comparing vision at contrasts of 1:5 and lower. In addition, mesopic is considerably reduced in high myopes even preoperatively.
Mohamed Mostafa, Engy
Purpose. To evaluate the effect of preoperative and postoperative keratometry on the refractive outcome after laser in situ keratomileusis (LASIK) for moderate and high myopia. Methods. Records of 812 eyes (420 patients) with myopia ≥−6 D who had LASIK at Sohag Laser Center, Egypt, from January 2010 to November 2013, were retrospectively analyzed. Main outcome measures were postoperative corrected distance visual acuity (CDVA), postoperative spherical equivalence, and postoperative Q factor. Results. LASIK was performed in 812 eyes (mean age 21.8 ± 5.2 years). Patients were grouped according to the degree of preoperative myopia into three groups: Group 1, −6 D to −7.9 D; Group 2, −8 to −9.9 D; and Group 3, −10 to −12 D. The refractive outcome among the different myopia groups was stratified by pre- and postoperative keratometry. A trend toward greater undercorrection was noted in eyes with preoperative keratometry <43.5 D compared with those with steeper keratometry >46 D in all myopia groups. The undercorrection was also noted in postoperative keratometry groups <35 D. Conclusions. Preoperative and postoperative keratometry appeared to influence the refractive outcome especially in high myopic eyes. PMID:26693347
Srivannaboon, Sabong; Chansue, Ekktet
To investigate intraoperative perception and sensation during Laser in situ Keratomileusis (LASIK). Sixty patients with uneventful LASIK were included. All procedures were performed by one surgeon with one technique. Any patient with intra-operative complications was excluded. The patients were asked to fill in the subjective evaluation form regarding their perception and sensation during the operation. Twenty-nine patients (48%) reported no pain and twenty-six patients (43%) reported no burning sensation during the surgery. Nineteen patients (32%) reported no light perception during the suction period of microkeratome. There was no correlation between duration of the suction and no light perception (R2 0.01). Thirty-four patients (56%) reported no trouble in maintaining visual fixation at the red light during the laser treatment. Ten patients (16%) reported they could clearly see the movement during the surgery and 5 out of 10 patients (50% of 16%) reported visual frightening. Fifty cases (84%) reported no visual frightening during the surgery after reassurance of the visual experience by the surgeon before the surgery. Patients undergoing LASIK may experience different visual perceptions. Reassurance of the intraoperative perception and sensation before the surgery can reduce the visual frightening.
Describes the nature of gradient refractive index (GRIN) lenses, focusing on refraction in these materials, focal length of a thin Wood lens, and on manufacturing of such lenses. Indicates that GRIN lenses of small cross section are in limited production with applications suggested for optical communication and photocopying fields. (JN)
The evolution of scleral lenses has led to new formulations of scleral fitting concepts and designs. The diameters of modern scleral lenses have been overhauled too and they are smaller comparing to the original ones. Nowadays, prescription of mini-sclerals supposedly seems in major extension and it appears indeed the necessity of some practitioner to differentiate the smaller mini-scleral lenses from larger mini-scleral lenses empathizing that they are the "smaller" ones. Therefore, it is maybe, necessary a definition of mini-scleral lenses referring to the landing zone width in relation to the horizontal visible iris diameter (HVID) and the limbus extension. The choice of the total diameter is crucial for a successful fitting and it depends majorly on patient's topographic patterns and anatomic factors. However, there are other important criteria for the selection of the scleral lens diameter based on oxygen supply, bubbles formation, mechanical stress on a toric sclera, ocular surface disease protection, entity of the vault over the cornea and distribution of the lens weight on the sclera. The advantages of mini-scleral lenses are various nonetheless in some cases large lenses are necessary. This paper presents a review of the benefits and disadvantages of both mini and large scleral lenses analyzing the conditions in which it may be better to prefer one diameter to another. A suggestion may be that to start fitting the smallest lens as possible, depending on the dimension of HVID and limbus width and consider larger lenses only when issues occur. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Thompson, Keith P.; Staver, P. Randall; Garcia, Jose R.; Burns, Stephen A.; Webb, Robert H.; Stulting, R. Doyle
Objective To compare visual outcomes in eyes undergoing aberrometry-guided (InterWave) LASIK with those in eyes undergoing standard LASIK treatment based upon refractive measures. Design Single-center, comparative, interventional, consecutive case series. Participants Four hundred two consecutive eyes undergoing LASIK were analyzed retrospectively. One group, 106 eyes undergoing primary LASIK and 224 eyes undergoing LASIK enhancement, was treated with standard LASIK treatment using a 5.5-mm optical zone, 1.5-mm transition zone laser with the settings determined by manifest refraction. The second group, 44 untreated (primary) eyes and 28 previously treated (enhancement) eyes, received a multipass, multistage treatment in which the laser settings for each stage were determined by aberrometry measurements. Eyes with desired monovision (undercorrected) outcome and preoperative hyperopia were excluded from the study. Intervention An aberrometry-guided laser treatment (InterWave LASIK) was compared with the standard LASIK treatment based upon the manifest refraction. Main Outcome Measures Uncorrected visual acuity (VA), manifest refraction, best spectacle-corrected VA (BSCVA), severity of halos, and root mean square (RMS) retinal blur area measured at 3 months postoperatively. Results Three months postoperatively there was no difference in uncorrected VA, BSCVA, refraction, or RMS retinal blur areas for pupil sizes of 3.5 mm between eyes treated by InterWave and those treated by standard LASIK. However, InterWave LASIK reduced the retinal blur area by 48% (P<0.0103) and 58% (P<0.0004) in primary cases and 43% (P<0.0430) and 74% (P<0.0271) in enhancement cases, respectively, for pupil sizes of 4.5 and 6.5 mm relative to standard LASIK treatments. Patients undergoing InterWave-guided treatment reported less severity of halo (0.37 vs. 0.98 [P<0.016] for primary cases and 0.35 vs. 0.73 [P<0.04] for enhancement cases). Conclusion InterWave LASIK achieved acuity and refractive
Childs, Andre; Li, Hao; Lewittes, Daniella M.; Dong, Biqin; Liu, Wenzhong; Shu, Xiao; Sun, Cheng; Zhang, Hao F.
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.
Bower, Kraig S.; Sia, Rose K.; Ryan, Denise S.; Mines, Michael J.; Dartt, Darlene A.
Purpose To evaluate dry eye manifestations following photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) and determine the incidence and predictive factors of chronic dry eye using a set of dry eye criteria. Setting Walter Reed Army Medical Center, Washington, DC, USA Methods This is a prospective non-randomized clinical study of 143 active duty U.S. Army personnel aged 29.9±5.2 years with myopia or myopic astigmatism (manifest spherical equivalent −3.83±1.96 diopters) undergoing either PRK or LASIK. Dry eye evaluation was performed pre- and postoperatively. Main outcome measures included dry eye manifestations, incidence, and predictive factors of chronic dry eye. Results Schirmer scores, corneal sensitivity, ocular surface staining, surface regularity index (SRI), and responses to dry eye questionnaire significantly changed over time after PRK. After LASIK, significant changes were observed in tear breakup time, corneal sensitivity, ocular surface staining, and responses to questionnaire. At twelve months postoperatively, 5.0% of PRK and 0.8% of LASIK participants developed chronic dry eye. Regression analysis showed preoperatively lower Schirmer score will significantly influence development of chronic dry eye after PRK whereas preoperatively lower Schirmer score or higher ocular surface staining score will significantly influence the occurrence of chronic dry eye after LASIK. Conclusions Chronic dry eye is uncommon after PRK and LASIK. Ocular surface and tear film characteristics during preoperative examination may help predict chronic dry eye development in PRK and LASIK. PMID:26796443
Seider, Michael I.; McLeod, Stephen D.; Porco, Travis C.; Schallhorn, Steven C.
Objective To determine if procedure room temperature and humidity during LASIK affects refractive outcomes in a very large patient sample. Design Retrospective cohort study. Participants 202,394 eyes of 105,712 patients aged 18 to 75 years old who underwent LASIK at an Optical Express, Inc. location in their United Kingdom and Ireland centers from January 1, 2008 to June 30, 2011 who met inclusion criteria. Methods Patient age, gender, pre- and one month post-LASIK manifest refraction and flap creation technique were recorded as well as the ambient temperature and humidity during LASIK. Effect size determination, in addition to univariate and multivariate analysis was performed to characterize the relationships between LASIK procedure room temperature and humidity and post-operative refractive outcome. Main Outcome Measures One month post-LASIK manifest refraction. Results No clinically significant effect of procedure room temperature or humidity was found on LASIK refractive outcomes. When considering all eyes in our population, an increase of one degree Celsius during LASIK was associated with a 0.003 diopter more hyperopic refraction one month post-operatively and an increase in one percent humidity was associated with a 0.0004 more myopic refraction. These effect sizes were the same or similar when considering only myopic eyes, only hyperopic eyes and subgroups of eyes stratified by age and pre-operative refractive error. Conclusions Procedure room temperature or humidity during LASIK was found to have no clinically significant relationship with post-operative manifest refraction in our population. PMID:23769199
Harris, M G; Rich, J; Tandrow, T
This study was designed to determine if spin-cast hydrogel contact lenses rotate on the eye, and if so, to investigate the parameters which influence rotation. If these lenses do rotate, correction of residual astigmatism may be difficult, if not impossible. We monitored the lens rotation associated with 12 specially marked B and L Soflens TM contact lenses on six corneas after insertion and 30 minutes later by use of high speed motion pictures. To analyze lens rotation, the film was projected with a stop action projector and the amount of rotation measured with a protractor. Thirty-one percent of the 144 observations made showed some lens rotation, the majority of which was encyclorotation. Most of the lenses showed little or no change in rotation between the two time periods. Corneal curvature was the only lens or eye parameter associated with rotation. Why lenses were more likely to rotate on steeper corneas is not fully understood. Our findings indicate that Softlenses TM may rotate, but there is no definite way of determining in advance if a given lens will rotate on a given eye. This emphasizes the need for individualized lens fitting and proper patient monitoring.
Lapple, W J; Snyder, A C; Tuovinen, O H
Microbial bioburden of contact lenses was evaluated in connection with lens care by refrigeration. Subjects wore new hydrogel contact lenses for approximately 8 hours. The microbial bioburden initially and after an overnight refrigeration of the lens was evaluated with the use of viable counts on three different media. No major changes in viable counts were observed resulting from this method of storage. Scanning electron microscopy indicated the presence of foreign material on both new and worn lenses, presumed to be debris from lens manufacture and mucoid deposits from daily wear. Microbial colonization was not apparent and single bacterial cells could not be discerned on the micrographs.
Terry, R; Schnider, C; Holden, B A
The introduction of new rigid gas permeable (RGP) contact lens materials provides the practitioner with a number of alternatives for patient management. But whatever the lens materials used, problems related to the lenses, care and maintenance solutions, and patients may arise. This paper examines concerns such as parameter instability, durability of lenses, compatibility of materials and solutions, patient education and compliance, 3 and 9 o'clock staining, corneal distortion, and lid changes. Suggestions are made on ways to avoid or minimize problems related to RGP lens wear.
Deflection of light by gravity was predicted by General Relativity and observationally confirmed in 1919. In the following decades, various aspects of the gravitational lens effect were explored theoretically. Among them were: the possibility of multiple or ring-like images of background sources, the use of lensing as a gravitational telescope on very faint and distant objects, and the possibility of determining Hubble's constant with lensing. It is only relatively recently, (after the discovery of the first doubly imaged quasar in 1979), that gravitational lensing has became an observational science. Today lensing is a booming part of astrophysics. In addition to multiply-imaged quasars, a number of other aspects of lensing have been discovered: For example, giant luminous arcs, quasar microlensing, Einstein rings, galactic microlensing events, arclets, and weak gravitational lensing. At present, literally hundreds of individual gravitational lens phenomena are known. Although still in its childhood, lensing has established itself as a very useful astrophysical tool with some remarkable successes. It has contributed significant new results in areas as different as the cosmological distance scale, the large scale matter distribution in the universe, mass and mass distribution of galaxy clusters, the physics of quasars, dark matter in galaxy halos, and galaxy structure. Looking at these successes in the recent past we predict an even more luminous future for gravitational lensing. Supplementary material is available for this article at 10.12942/lrr-1998-12.
Drijvers, Paul; Godino, Juan D.; Font, Vicenc; Trouche, Luc
A deep understanding of students' learning processes is one of the core challenges of research in mathematics education. To achieve this, different theoretical lenses are available. The question is how these different lenses compare and contrast, and how they can be coordinated and combined to provide a more comprehensive view on the topic of…
Washer and F. Roseberry , 41, 597 (Dec 49). Spurious Resolution of Photographic Lenses, R. HotcbJrias, F. E. Washer, and F. Roseberry , 41, 600 (Sep...Lena — Emulsion Performance — R. L. Williams ,*. 50 (Nov 1940). Measuring the Resolving Power of Lenses, r C. W. Kendall and B. A. Schumacher, i
Jeweler, Sue; Barnes-Robinson, Linda
When parents and teachers help gifted kids use the metaphor "learning through different lenses," amazing things happen: Horizons open up. Ideas are focused. Thoughts are magnified and clarified. They see the big picture. Metaphoric thinking offers new and exciting ways to see the world. Viewing the world through different lenses provides…
The protective efficacy and safety of bandage contact lenses in children aged 5 to 11 after frontalis muscle flap suspension for congenital blepharoptosis: A single-center randomized controlled trial.
Chen, Lin; Pi, Lianhong; Ke, Ning; Chen, Xinke; Liu, Qing
Postoperative complications, lagophthalmos and exposure keratopathy sometimes occur after surgery for congenital blepharoptosis. Bandage contact lenses (BCL) can help prevent some ocular surface disorders. The study aims to evaluate the efficacy and safety of BCL for protection of the ocular surface in children aged 5 to 11 years after frontalis muscle flap suspension for congenital blepharoptosis. We conducted a prospective randomized clinical study of 30 eyes of 30 patients with congenital blepharoptosis consecutively enrolled at the Ophthalmology Ward of the Children's Hospital of Chongqing Medical University, China from September 1, 2016, to February 30, 2017. After frontalis muscle flap suspension surgery, patients were randomly assigned to undergo BCL application (BCL group, 15 eyes) or no BCL application (control group, 15 eyes). All patients were treated with bramycin 0.3% and polyvinyl alcohol drops after surgery. The primary outcomes were dry eye assessed by tear film break time (TFBUT), fluoresce in corneal staining (FCS) on slit-lamp on days 1, 3, and 15 postoperatively, and lower tear meniscus height (LTMH) on optical coherence tomography on days 1 and 15 postoperatively. Secondary outcomes were pairwise correlation of TFBUT, FCS and LTMH. In the BCL group, abnormal TFBUT and FCS were only found in 2 patients (13.33%) on postoperative day 15. In the control group, the incidence of dry eye assessed by TFBUT was 67.00% (10/15 eyes) on day 1, 73.33% (11/15 eyes) on day 3, and 53.33% (8/15 eyes) on day 15 (P < .001). LTMH were significantly higher in the BCL group than the control group postoperatively (P < .001). Significant positive correlations were found between LTMH and TFBUT pre-operation and on days 1 and 15 post-operation. For LTMH and FCSS (R = -0.815, P < .001), and TFBUT and FCS (R = -0.837, P < .001), the Pearson coefficient was negative on postoperative day 1, but not correlated on day 15. Silicone hydrogel BCL were
Mackool, Richard J; Monsanto, Vivian R
We describe a surgical technique to manage persistent corneal striae after laser in situ keratomileusis (LASIK). The sequential lift and suture technique reduces the time required for LASIK, eliminates the need to fixate the flap with forceps during suturing, and increases the accuracy of suture placement. The results in 10 eyes (9 patients) showed complete resolution of striae with improvement in subjective symptoms (glare and blurred vision) and best corrected visual acuity.
Lazon de la Jara, P; Erickson, D; Erickson, P; Stapleton, F
Purpose The aim of this study was to determine how laser in situkeratomileusis (LASIK) affects quality of life (QOL) and to identify factors that may affect satisfaction after LASIK. Methods A total of 104 patients with a mean age of 29±6, treated with LASIK for myopia and astigmatism, were enrolled in a prospective study. High (90%) and low (10%) contrast visual acuity (CVA) were measured under photopic and scotopic conditions before surgery and at 3 months later. A multidimensional QOL scale (Institute for Eye Research multidimensional QOL scale), which assesses psychological characteristics, personality traits, cosmesis, frequency, and tolerance to disturbing visual and ocular symptoms, and overall satisfaction with vision correction, was also used. Paired rank tests were used to compare preoperative and postoperative vision and QOL scores. Correlations and a multiple linear regression were used to describe the relationship between CVA, QOL, and satisfaction after LASIK. Results Significant postoperative changes included increased satisfaction following LASIK (P<0.001), reduced frequency of visual and ocular symptoms (P<0.001), and change in psychological characteristics (P=0.033). The change in satisfaction with LASIK can be predicted by a combination of preoperative satisfaction, postoperative frequency of disturbing visual and ocular symptoms, postoperative mean spherical equivalent, and postoperative scotopic high CVA (R 2=0.725, P<0.05). Conclusions Satisfaction with LASIK is related to visual function, preoperative expectations, psychological characteristics, and uncorrected CVA achieved. An increased sense of subjective well-being, adaptability, and self-efficacy was evident after LASIK. Patients reported a more optimistic attitude to life and increase perceived QOL after surgery. PMID:21720417
Newbury, P. R.; Spiteri, R. J.
Gravitational lensing provides a powerful tool to study a number of fundamental questions in astrophysics. Fortuitously, one can begin to explore some non-trivial issues associated with this phenomenon without a lot of very sophisticated mathematics, making an elementary treatment of this topic tractable even to senior undergraduates. In this paper, we give a relatively self-contained outline of the basic concepts and mathematics behind gravitational lensing as a recent and exciting topic for courses in mathematical modeling or scientific computing. To this end, we have designed and made available some interactive software to aid in the simulation and inversion of gravitational lenses in a classroom setting.
An Ames Research Center scientist invented an infrared lens used in sunglasses to filter out ultraviolet rays. This product finds its origins in research for military enemy detection. Through a Space Act Agreement, Optical Sales Corporation introduced the Hawkeye Lenses not only as sunglasses but as plant stress detection lenses. The lenses enhance the stressed part of the leaf, which has less chlorophyll than healthy leaves, through dyes that filter out certain wavelengths of light. Plant stress is visible earlier, at a stage when something can be done to save the plants.
In addition to multiply-imaged quasars, a number of other aspects of lensing have been discovered: For example, giant luminous arcs, quasar microlensing, Einstein rings, galactic microlensing events, arclets, and weak gravitational lensing. At present, literally hundreds of individual gravitational lens phenomena are known. Although still in its childhood, lensing has established itself as a very useful astrophysical tool with some remarkable successes. It has contributed significant new results in areas as different as the cosmological distance scale, the large scale matter distribution in the universe, mass and mass distribution of galaxy clusters, the physics of quasars, dark matter in galaxy halos, and galaxy structure. Looking at these successes in the recent past we predict an even more luminous future for gravitational lensing.
Fogt, N; Jones, R
The accuracy of directional localization with refractive lenses was determined by open-loop pointing for four myopic habitual contact lens wearers. The target was a single point of light at random locations (dark), or was embedded in a horizontal array of lights (light). In the dark, the regression slope of indicated vs actual target position was significantly less for spectacles than for contact lenses, as predicted from the prismatic effects of the spectacles. In the light, slopes for spectacles and contacts were not significantly different. These results suggest that spectacle wearers do not utilize eye position information in making direction judgments in the light.
The author presents his views on the implantation of intraocular lenses, in connection with two pseudophakic bullous keratopathy cases. There is no medical indication for implantation. The question is whether the most important function of the eye, object vision, may be risked in order to avoid aniseikonia or to restore binocular vision? Knowing that vision can be restored with glasses or contact lenses, is it ethical to induce more or less severe postoperative complications by means of intraocular lenses? In view of the considerable success often achieved immediately after the operation, complications which may not arise years later should also be taken into consideration.
Akhtar, Saeed; Alkatan, Hind; Kirat, Omar; Almubrad, Turki
Post-laser in situ keratomileusis (LASIK) corneal ectasia is a serious late postoperative complication. Here, we report the ultrastructural features of the post-LASIK cornea of two patients. Two normal corneas (age 24 and 37 years old) and two post-LASIK ectaic corneas from two patients (A and B) were studied. The "patient A" (age 27 years) underwent penetrating keratoplasty and "patient B" (age 31 years) underwent deep-anterior lamellar keratoplasty. The excised corneas were processed for light and electron microscopy. A total of 120 images for three-dimensional (3D) reconstruction were taken by using the software "Recorder" and using a bottom mounted camera "Quemesa" attached to a JOEL 1400 transmission electron microscope. The 3D images were constructed using "Visual Kai" software. In the post-LASIK cornea, the hemidesmosomes, the basement membrane, and Bowman"s layer were abnormal. The stromal lamellae were thin and disorganized. The collagen fibrils (CFs) diameter and interfibrillar spacing had decreased. Aggregated microfibrils were present in the Bowman's layer and all parts of the stroma. A large number of microfilaments were present at the detachment end of the flap and residual stroma. The 3D images showed the presence of collagen microfibrils and proteoglycans (PGs) within the CF of the normal and post-LASIK cornea. The collagen microfibrils and PGs within the CFs had degenerated in the post-LASIK cornea. Collagen microfibrils and PGs within the CFs were degenerated, leading to the degeneration of CFs, followed by the disorganization of lamellae in post-LASIK cornea. The CFs diameter and interfibrillar spacing decreased. Copyright © 2013 Wiley Periodicals, Inc.
Anton, A; Neuburger, M; Jordan, J F; Wecker, T; Lübke, J; Heinzelmann, S; Lapp, T; Böhringer, D; Reinhard, T; Maier, P
The reduction of corneal thickness following laser-assisted in-situ keratomileusis (LASIK) requires a correction of intraocular pressure (IOP) measurements. The corneal visualization Scheimpflug technology (CorVis ST, Oculus, Wetzlar, Germany) not only measures the IOP and central corneal thickness (CCT) but also determines 10 additional corneal parameters, such as the time to first and second applanation and velocity. Besides CCT we compared various corneal parameters before and after LASIK in order to detect possible correlations and to correct IOP measurements. Measurements with CorVis ST were made before and after LASIK in 45 myopic patients (45 left eyes). We compared the IOP and CorVis ST parameters using a paired t‑test before and after LASIK and corrected for possible correlations in a multifactorial linear model. Finally, we correlated the changes in IOP to changes in biomechanical parameters. We observed a direct correlation between the IOP measurements and the corneal thickness. The IOP was underestimated by 0.039 mm Hg per micrometer in reduction of corneal thickness. The multifactorial linear model showed a correlation of IOP change to A2 velocity and the radius of applanation. Surgical thinning of the central cornea via LASIK demonstrated a direct correlation between corneal thickness and IOP measurements using the CorVis ST technique. Postoperative changes of the A2 velocity and the applanation radius also had a statistically significant influence on post-LASIK IOP measurements. Our findings could be useful to obtain more precise post-LASIK IOP measurements.
Cox, Daniel J; Banton, Thomas; Record, Steven; Grabman, Jesse H; Hawkins, Ronald J
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
Dixon, J M
A self contained non commercial private office laboratory staffed by office personnel has been used to prepare contact lenses for private office patients. These lenses include hard contact lenses of various materials and various designs. During the past ten years extended wear hydrophilic soft lenses have been prepared in the same manner as hard lenses, all custom made with lens powers, base curves, diameters, and thickness designed according to the needs of each patient. This has provided strict medical supervision and lens maintenance with maximum convenience for patients and the ophthalmologist.
Chao, Cecilia; Golebiowski, Blanka; Zhao, Xiangtian; Chen, Shihao; Zhou, Shi; Stapleton, Fiona
To investigate the associations between dry eye, corneal nerves, and tear neuroptides in dry eye after LASIK. A single visit cross-sectional study was performed. Twenty participants who had LASIK more than 12 months prior and 20 healthy participants were recruited. Ocular comfort, tear functions, ocular surface sensitivity, basal tear collection, and corneal nerve morphology assessments were conducted. Tear substance P and calcitonin gene-related peptide (CGRP) concentrations were determined using ELISAs. Differences in variables between groups were examined using an independent t test or Mann-Whitney U test, as appropriate. Associations between variables in the post-LASIK group were examined using a Spearman's correlation test. A P value of less than .05 was considered significant. Central corneal nerve morphology parameters were all altered in the post-LASIK group (P < .05). Higher ocular discomfort (P = .01), tear CGRP concentration (P = .001), and conjunctival sensitivity (P < .009) were found in the post-LASIK group. There was a positive association between dry eye symptoms and superior corneal sensitivity (P = .51, P = .02) and tear substance P concentration (P = .52, P < .03). This study provides evidence of the association between tear neuropeptides, conjunctival sensitivity, and symptoms in symptomatic patients after LASIK. The differences in nerve morphology, neuropeptide, and ocular surface sensitivity between symptomatic and asymptomatic patients after LASIK are required to better understand the mechanism of dry eye after LASIK. [J Refract Surg. 2016;32(8):518-524.]. Copyright 2016, SLACK Incorporated.
Lei, Feng; Burns, Stephen A.; shao, Liqin; Yang, Yabo
Purpose To compare retinal measurements obtained by time domain optical coherence tomography (OCT) devices before and after myopic laser in situ keratomileusis (Lasik) and to assess the interaction of Lasik and retinal structures as measured by time domain OCT. Methods 53 patients randomly selected participated in the study. Only the right eye of each subject was included in the study. Comprehensive ophthalmic examinations including refraction examination, slitlamp examination, dilated fundus examination, corneal topography, corneal thickness, intraocular pressure, and retinal Stratus OCT scans were acquired for each patient before myopic Lasik and 3 months after surgery. Results Total macular volume (TMV) changed significantly between preoperative and postoperative measurements (p=0.003). No statistical differences were found between preoperative and postoperative disc area, rim area, cup/disk vert. ratio, or average foveal thickness (p>0.05). The variation in TMV correlated significantly with the change in spherical refraction equivalent, maximal corneal curvature, minimal corneal curvature, and corneal ablation depth. Conclusion Most retinal OCT measurements undergo no obvious changes after myopic Lasik. The increased TMV measurements we measured after Lasik seem to be correlated with the alteration in corneal shape. The exact mechanism for this change is not clear, while we examined several possibilities including subclinical macular edema, magnification changes, errors in OCT analysis and IOP, none of these seem to be a likely cause. PMID:22512373
Tan, Colin S H; Au Eong, Kah-Guan; Lee, Hung-Ming
To describe the loss of light perception and other visual experiences encountered during different stages of laser in situ keratomileusis (LASIK) and to compare patients' experiences between LASIK performed with the Zyoptix XP microkeratome and Intralase laser. Prospective, randomized, self-matched clinical study. Forty-one patients (82 eyes) had bilateral LASIK with the corneal flap fashioned by Zyoptix XP microkeratome in one eye and Intralase laser in the other. They were interviewed postoperatively with a standardized questionnaire about their intraoperative visual experiences, including light perception and ability to see the red fixation light. During both vacuum suction and corneal flap fashioning, a higher proportion of eyes in the Zyoptix XP microkeratome group lost light perception compared with the Intralase group (85.4% vs 39.0% and 90.2% vs 61.0%; P < .001 and P = .004, respectively). Patients also saw flashes, various colors, movement, the surgeon's hands or fingers, and the surgeon during surgery, and there was no difference in these visual experiences between the Zyoptix XP microkeratome and Intralase groups. Overall, eight (19.5%) of 41 patients were frightened by their intraoperative visual experiences during LASIK. Patients retain light perception during most stages of LASIK except during suction and fashioning of the corneal flap, when some are temporarily unable to see. Many also experience various visual sensations intraoperatively, and 19.5% of patients are frightened by their visual experiences.
Kanellopoulos, Anastasios John; Georgiadou, Stella; Asimellis, George
To evaluate corneal stromal thickness reduction and compare to attempted and achieved ablation depth in a consecutive case series study of myopic LASIK. Stromal thickness reduction was retrospectively evaluated in 205 consecutive eyes of 205 patients undergoing myopic and myopic astigmatic LASIK. Anterior segment optical coherence tomography was performed preoperatively and 3 months postoperatively. Epithelial thickness remodeling was also accounted for to achieve objective stromal thickness reduction. The derived maximum stromal thickness reduction was then compared to the programmed (planned) maximum ablation depth. Deviation of planned versus achieved maximum stromal thickness changes was correlated with residual refractive error. The 3-month stromal reduction was 86.01 ± 28.28 µm, compared to the average programmed maximum ablation depth of 88.48 ± 26.05 µm. The attempted versus achieved thickness outliers correlated with deviations in achieved refractive correction. Actual objective stromal thickness reduction following myopic LASIK correlates well with the attempted versus achieved refractive change. Copyright 2015, SLACK Incorporated.
Edens, Chris; Liebich, Lauren; Halpin, Alison Laufer; Moulton-Meissner, Heather; Eitniear, Samantha; Zgodzinski, Eric; Vasko, Larry; Grossman, David; Perz, Joseph F; Mohr, Marika C
Laser-assisted in situ keratomileusis (LASIK) eye surgery is increasingly common, with approximately 600,000 procedures performed each year in the United States. LASIK eye surgery is typically performed in an outpatient setting and involves the use of a machine-guided laser to reshape the lens of the eye to correct vision irregularities. Clinic A is an ambulatory surgery center that performs this procedure on 1 day each month. On February 5, 2015, the Toledo-Lucas County Health Department (TLCHD) in Ohio was notified of eye infections in two of the six patients who had undergone LASIK procedures at clinic A on January 9, 2015. The two patients experienced eye pain after the procedures and received diagnoses of infection with Mycobacterium chelonae, an environmental organism found in soil and water.
Strong gravitational lensing has now developed into a mature tool for investigating galactic structure and dynamics as well as cosmological models. In this lecture the phenomenon of strong gravitational lensing, its history and applications are reviewed with an emphasis on the recent ideas developed by the author. Expected massive discoveries of strong lensing galactic scale systems in forthcoming projects like Euclid or LSST herald the bright future of gravitational lensing in cosmology.
Biomedical Optical Company of America's (BOCA) suntiger lenses, similar in principle to natural filters in the eyes of hawks and eagles, bar 99 percent of potentially harmful wavelengths, while allowing visually useful colors of light (red, orange, green) to pass through. They also improve visual acuity, night vision and haze or fog visibility. The lenses evolved from work done by James B. Stephens and Dr. Charles G. Miller of the Jet Propulsion Laboratory. They developed a formula and produced a commercial welding curtain that absorbs, filters, and scatters light. This research led to protective glasses now used by dentists, workers in hazardous environments, CRT operators and skiers.
Cuadros, Juan; Gros-Otero, Juan; Gallego-Angui, Patricia; Scheu, Ann Karolin; Montes-Mollón, Ángeles; Pérez-Rico, Cinta; Moreno, Javier Paz; Gómez-Herruz, Peña; Soliveri, Juan; Teus, Miguel
Keratitis produced by Aspergillus tamarii has been previously described associated to an ocular injury. We report a case in a contact lens wearer with a history of previous bilateral myopic LASIK ablation, bilateral intracorneal rings and vitrectomy and scleral buckling in his left eye. The fungus could be quickly identified combining phenotype, microscopy and mass spectrometry. Treatment with intravenous amphotericin, oral voriconazole, and topical amphotericin and natamycin and voriconazole was needed for corneal preservation.
Schallhorn, Steven C; Teenan, David; Venter, Jan A; Schallhorn, Julie M; Hettinger, Keith A; Hannan, Stephen J; Pelouskova, Martina
To compare clinical and quality of life outcomes between patients who underwent monovision LASIK and refractive lens exchange. The study comprised 590 patients with refractive lens exchange and 608 patients with monovision LASIK available for 3-month postoperative clinical visits. All patients with refractive lens exchange had a Tecnis Symfony lens (Johnson & Johnson Vision Care, Inc., Santa Ana, CA) in at least one eye. Patients were divided into four refractive categories: moderate to high myopia, low myopia, plano presbyopia, and hyperopia. Three-month postoperative data were compared between monovision LASIK and refractive lens exchange for each group. Postoperatively, the percentage of patients with binocular uncorrected distance visual acuity of 20/20 or better, for monovision LASIK and refractive lens exchange, respectively, was as follows: moderate to high myopia: 84.7% vs 90.7% (P = .31), low myopia: 89.4% vs 85.2% (P = .45), plano presbyopia: 90.5% vs 89.9% (P = .90), and hyperopia: 77.5% vs 84.2% (P = .03). For near vision, the percentage with binocular near visual acuity of 20/40 or better (J5) at 40 cm was as follows: moderate to high myopia: 98.9% vs 90.7% (P < .01), low myopia: 100% vs 98.1% (P = .17), plano presbyopia: 96.8% vs 95.8% (P = .34), and hyperopia: 95.6% vs 95.7% (P = .96). There was a statistically significant difference in patient satisfaction in favor of monovision LASIK for moderate to high myopia (94.3% for monovision LASIK vs 79.1% for refractive lens exchange, P <.01). For all other refractive categories, there was no significant difference in patient satisfaction. All myopic patients with refractive lens exchange experienced more postoperative visual phenomena than patients with monovision LASIK. The plano presbyopia group had comparable visual phenomena between the two procedures. Monovision LASIK and refractive lens exchange are both reasonable options for presbyopic patients. [J Refract Surg. 2017;33(11):749-758.]. Copyright
Choi, Kyoungjun; Park, Hyung Gyu
With potential benefits to the 71 million contact lens users worldwide, contact lenses are being reinvented in the form of smart wearable electronics. In this issue of ACS Nano, Lee et al. report on the fascinating functions of a graphene-based smart contact lens that is able to protect eyes from electromagnetic waves and dehydration. Graphene and two-dimensional materials can be exploited in many opportunities in the development of smart contact lenses. Here, we briefly review and describe prospects for the future of smart contact lenses that incorporate graphene in their platforms.
Carney, L G; Hill, R M
Tear protein deposition on contact lenses can lead to interruption or even cessation of lens wear. Yet, there are positive roles that tear proteins play in the maintenance of ocular integrity, with and without contact lenses present. One of these roles, that of tear buffering, is explored here.
Greenslade, Thomas B., Jr.
One of the rewards of walking up the scores of steps winding around the inside of the shaft of a lighthouse is turning inward and examining the glass optical system. This arrangement of prisms, lenses, and reflectors is used to project the light from a relatively small source in a beam that can be seen far at sea.
Classé, J G
The use of forms in contact lens practice can save time, promote patient education, and reduce the opportunity for legal or economic disputes. The most commonly employed forms are those for contact lens fitting agreements, instructions for care and maintenance of lenses, prepaid service agreements, clinical investigations of investigatory lenses or solutions, and for extended wear patients. Sample forms are utilized for purposes of illustration.
All contact lenses with replacement schedules longer than daily must be maintained. At each step of their use, the lenses may be contaminated. Contact lens solutions perform the essential functions of cleaning, decontaminating and preserving the lenses to prevent infectious problems and improve wearing comfort. Contact lens contamination essentially comes from hands, cleaning solutions, cases, water and the environment. The pathogenic microorganisms are mainly Gram-negative bacteria, fungi and amoebae. Contact lens deposits may or may not have an organic origin. Their presence increases the risk of infection because they serve as a nutrient matrix for microbes, and they are responsible for wearing discomfort. Contact lens solutions differ in their composition, their mechanism of action and the concentration of the various agents. To prescribe the best lens care system to each wearer and for each material, it is necessary to be very familiar with them. Maintenance is the main cause of discomfort with contact lenses, either through improper use, solution-material incompatibility, or a reaction of the wearer to the components. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
Frings, Andreas; Steinberg, Johannes; Druchkiv, Vasyl; Linke, Stephan J; Katz, Toam
Previous studies have suggested that, to improve refractive predictability in hyperopic LASIK treatments, preoperative cycloplegic or manifest refraction, or a combination of both, could be used in the laser nomogram. We set out to investigate (1) the prevalence of a high difference between manifest and cycloplegic spherical equivalent in hyperopic eyes preoperatively, and (2) the related predictability of postoperative keratometry. Retrospective cross-sectional data analysis of consecutive treated 186 eyes from 186 consecutive hyperopic patients (mean age 42 [±12] years) were analyzed. Excimer ablation for all eyes was performed using a mechanical microkeratome (SBK, Moria, France) and an Allegretto excimer laser platform. Two groups were defined according to the difference between manifest and cycloplegic spherical equivalent which was defined as ≥1.00 diopter (D); the data was analyzed according to refractive outcome in terms of refractive predictability, efficacy, and safety. In 24 eyes (13 %), a preoperative difference of ≥1.00D between manifest spherical equivalent and cycloplegic spherical equivalent (= MCD) occurred. With increasing preoperative MCD, the postoperative achieved spherical equivalent showed hyperopic regression after 3 months. There was no statistically significant effect of age (accommodation) or optical zone size on the achieved spherical equivalent. A difference of ≥1.00D occurs in about 13 % of hyperopia cases. We suggest that hyperopic correction should be based on the manifest spherical equivalent in eyes with preoperative MCD <1.00D. If the preoperative MCD is ≥1.00D, treatment may produce manifest undercorrection, and therefore we advise that the patient should be warrned about lower predictability, and suggest basing conclusions on the arithmetic mean calculated from the preoperative manifest and cycloplegic spheres.
Learning unit: Thin lenses "Why objects seen through lenses are sometimes upright and sometimes reversed" Nita Laura Simona National College of Arts and Crafts "Constantin Brancusi", Craiova, Romania 1. GEOMETRIC OPTICS. 13 hours Introduction (models, axioms, principles, conventions) 1. Thin lenses (Types of lenses. Defining elements. Path of light rays through lenses. Image formation. Required