... Consumer Devices Consumer Products Contact Lenses Types of Contact Lenses Share Tweet Linkedin Pin it More sharing ... Orthokeratology (Ortho-K) Decorative (Plano) Contact Lenses Soft Contact Lenses Soft contact lenses are made of soft, ...
... vision problems; this includes prescribing eyeglasses and contact lenses, but also doing eye surgery for other eye-related problems. An optometrist ... them clean. The most important thing about contact lenses is good hygiene to prevent infections in your eye. But the really fun part of new glasses ...
Kingston, David W.
Summarizes results of a three-item questionnaire returned by 43 Michigan institutions expressing views on wearing contact lenses in chemical laboratories. Questions focused on eye protection, type of protection, and use of contact lenses. (SK)
... Vea esta página en español The Basics of LASIK Eye Surgery Share This Page Facebook Twitter Linked- ... Surgery Surgical Alternatives to LASIK For More Information LASIK Basics If you wear glasses or contact lenses, ...
... of this Web site is to provide objective information to the public about LASIK surgery. See other ... undergoing LASIK surgery. This web site also provides information on FDA’s role in LASIK surgery, FDA’s current ...
Badawy, Abdel-Rahman; Hassan, Muhammad Umair; Elsherif, Mohamed; Ahmed, Zubair; Yetisen, Ali K; Butt, Haider
Color vision deficiency (color blindness) is an inherited genetic ocular disorder. While no cure for this disorder currently exists, several methods can be used to increase the color perception of those affected. One such method is the use of color filtering glasses which are based on Bragg filters. While these glasses are effective, they are high cost, bulky, and incompatible with other vision correction eyeglasses. In this work, a rhodamine derivative is incorporated in commercial contact lenses to filter out the specific wavelength bands (≈545-575 nm) to correct color vision blindness. The biocompatibility assessment of the dyed contact lenses in human corneal fibroblasts and human corneal epithelial cells shows no toxicity and cell viability remains at 99% after 72 h. This study demonstrates the potential of the dyed contact lenses in wavelength filtering and color vision deficiency management. © 2018 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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
Steinbach, P D; Nover, A
If it is necessary to prescribe contact lenses for children, this correction should be made as soon as possible. As a consequence of the development of soft (hydrophile) lenses, the above mentioned group of patients has increased considerably. In any case, a monolateral aphakia as well as a manifest anisometropia should be corrected by a contact lense to avoid amblyopia, heterotropia and loss of stereoscopic vision. Usually soft lenses are well tolerated, so that patients suffering from aphakia as well as hyperopia should always use this type of lense. Nevertheless, the hard lense still has its indication in treating myopia and high astigmatism.
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
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.
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
Jain, M. R.
Clinical studies were conducted on 466 patients waiting for senile cataract surgery and receiving chloromycetin, gentamicin, or carbenicillin subconjunctivally and through New Sauflon 70 and New Sauflon 85 lenses. The aqueous drug levels were biologically estimated at various time intervals. Soft contact lenses provided significantly higher drug penetration than subconjunctival therapy. Both modes of treatment provided therapeutically effective levels against most of the common ocular pathogens for varying intervals of 2 to 12 hours. PMID:3349016
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.
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. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. 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 ...
Atchison, D A
A rigid contact lens on an eye can produce levels of spherical aberration very different from those produced by a spectacle lens in front of the eye. These levels are considerably affected by contact lens surface asphericity. Change in longitudinal spherical aberration associated with aspherizing a contact lens surface is well predicted by a simple equation for change in sagittal power of the surface. Displacing an aspheric contact lens on the eye can produce considerable defocus, which is well predicted by simple equations for change in sagittal and tangential surface powers. The best refractive correction with contact lenses can be determined only by overrefraction with a patient wearing a contact lens of power and characteristics similar to that which will be prescribed. An aspheric contact lens that moves to a considerable extent on the eye will cause more unstable vision than will a spherical lens that moves to the same extent.
Harris, M G; Haririfar, M; Hirano, K Y
Tinted and ultraviolet (UV)-blocking disposable contact lenses have become increasingly popular over the last decade. Wearers of UV-blocking contact lenses could benefit greatly by protecting their eyes from potential UV radiation damage. A Uvikon 930 dual beam spectrophotometer was used to measure three enhancement-tinted lenses (royal blue, evergreen, and aqua), two types of UV-blocking lenses, and two types of non-UV-blocking lenses. Enhancement-tinted lenses did show a decrease in transmittance at certain wavelengths on the visible spectrum, but they did not reduce the transmittance of UV radiation to the extent of the UV-blocking lenses designed specifically for this purpose.
Gifford, Paul; Gifford, Kate Louise
The growing incidence of pediatric myopia worldwide has generated strong scientific interest in understanding factors leading to myopia development and progression. Although contact lenses (CLs) are prescribed primarily for refractive correction, there is burgeoning use of particular modalities for slowing progression of myopia following reported success in the literature. Standard soft and rigid CLs have been shown to have minimal or no effect for myopia control. Overall, orthokeratology and soft multifocal CLs have shown the most consistent performance for myopia control with the least side effects. However, their acceptance in both clinical and academic spheres is influenced by data limitations, required off-label usage, and a lack of clear understanding of their mechanisms for myopia control. Myopia development and progression seem to be multifactorial, with a complex interaction between genetics and environment influencing myopigenesis. The optical characteristics of the individual also play a role through variations in relative peripheral refraction, binocular vision function, and inherent higher-order aberrations that have been linked to different refractive states. Contact lenses provide the most viable opportunity to beneficially modify these factors through their close alignment with the eye and consistent wearing time. Contact lenses also have potential to provide a pharmacological delivery device and a possible feedback mechanism for modification of a visual environmental risk. An examination of current patents on myopia control provides a window to the future development of an ideal myopia-controlling CL, which would incorporate the broadest treatment of all currently understood myopigenic factors. This ideal lens must also satisfy safety and comfort aspects, along with overcoming practical issues around U.S. Food and Drug Administration approval, product supply, and availability to target populations. Translating the broad field of myopia research
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.
de Luis Eguileor, Beatriz; Etxebarria Ecenarro, Jaime; Santamaria Carro, Alaitz; Feijoo Lera, Raquel
To assess visual function in patients with irregular cornea who do not tolerate gas permeable (GP) corneal contact lenses and are fitted with GP scleral contact lenses (Rose K2 XL). In this prospective study, we analyzed 15 eyes of 15 patients who did not tolerate GP corneal contact lenses and were fitted with scleral contact lenses (Rose K2 XL). We assessed visual function using visual acuity and the visual function index (VF-14); we used the VF-14 as an indicator of patient satisfaction. The measurements were taken with the optical correction used before and 1 month after the fitting of the Rose K2 XL contact lenses. We also recorded the number of hours lenses had been worn over the first month. Using Rose K2 XL contact lenses, visual acuity was 0.06±0.07 logMAR. In all cases, visual acuity had improved compared with the measurement before fitting the lenses (0.31±0.18 logMAR; P=0.001). VF-14 scores were 72.74±12.38 before fitting of the scleral lenses, and 89.31±10.87 after 1 month of lens use (P=0.003). Patients used these scleral lenses for 9.33±2.99 comfortable hours of wear. Both visual acuity and VF-14 may improve after fitting Rose K2 XL contact lenses in patients with irregular corneas. In addition, in our patients, these lenses can be worn for a longer period than GP corneal contact lenses.
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
Background This study aimed to evaluate the adhesion of Acanthamoeba trophozoites on cosmetic contact lenses (CLs) with and without CL care multipurpose solution (MPS) treatment. Methods 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. Results 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. Conclusion 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. PMID:29318793
Wang, Yingming; Qian, Xuefeng; Zhang, Xiaofeng; Xia, Wei; Zhong, Lei; Sun, Zhengtai; Xia, Jing
Contact lens safety is an important topic in clinical studies. Corneal infections usually occur because of the use of bacteria-carrying contact lenses. The current study investigated the impact of plasma surface modification on bacterial adherence to rigid contact lenses made of fluorosilicone acrylate materials. Boston XO and XO2 contact lenses were modified using plasma technology (XO-P and XO2-P groups). Untreated lenses were used as controls. Plasma-treated and control lenses were incubated in solutions containing Staphylococcus aureus or Pseudomonas aeruginosa. MTT colorimetry, colony-forming unit counting method, and scanning electron microscopy were used to measure bacterial adhesion. MTT colorimetry measurements showed that the optical density (OD) values of XO-P and XO2-P were significantly lower than those of XO and XO2, respectively, after incubation with S. aureus (P < 0.01). The OD value of XO-P was also much lower than that of XO after incubation with P. aeruginosa (P < 0.01). Colony-forming unit counting revealed that a significantly lower number of bacterial colonies attached to the XO-P versus XO lenses and to the XO2-P versus XO2 lenses incubated with S. aureus (P < 0.01). Fewer bacterial colonies attached to the XO-P versus XO lenses incubated with P. aeruginosa (P < 0.01). Further, scanning electron microscopy suggested different bacterial adhesion morphology on plasma-treated versus control lenses. Plasma surface modification can significantly decrease bacterial adhesion to fluorosilicone acrylate contact lenses. This study provides important evidence of a unique benefit of plasma technology in contact lens surface modification.
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.
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.
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...
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.
Babaei Omali, Negar; Zhu, Hua; Zhao, Zhenjun; Ozkan, Jerome; Xu, Banglao; Borazjani, Roya; Willcox, Mark D P
To examine the effect of cholesterol on the adhesion of bacteria to silicone hydrogel contact lenses. Contact lenses, collected from subjects wearing Acuvue Oasys or PureVision lenses, were extracted in chloroform:methanol (1:1, v/v) and amount of cholesterol was estimated by thin-layer chromatography. Unworn lenses were soaked in cholesterol, and the numbers of Pseudomonas aeruginosa strains or Staphylococcus aureus strains that adhered to the lenses were measured. Cholesterol was tested for effects on bacterial growth by incubating bacteria in medium containing cholesterol. From ex vivo PureVision lenses, 3.4 ± 0.3 μg/lens cholesterol was recovered, and from Acuvue Oasys lenses, 2.4 ± 0.2 to 1.0 ± 0.1 μg/lens cholesterol was extracted. Cholesterol did not alter the total or viable adhesion of any strain of P. aeruginosa or S. aureus (p > 0.05). However, worn PureVision lenses reduced the numbers of viable cells of P. aeruginosa (5.8 ± 0.4 log units) compared with unworn lenses (6.4 ± 0.2 log units, p = 0.001). Similarly, there were fewer numbers of S. aureus 031 adherent to worn PureVision (3.05 ± 0.8 log units) compared with unworn PureVision (4.6 ± 0.3 log units, p = 0.0001). Worn Acuvue Oasys lenses did not affect bacterial adhesion. Cholesterol showed no effect on the growth of any test strain. Although cholesterol has been shown to adsorb to contact lenses during wear, this lipid does not appear to modulate bacterial adhesion to a lens surface.
Willcox, Mark D P; Naduvilath, Thomas J; Vaddavalli, Pravin K; Holden, Brien A; Ozkan, Jerome; Zhu, Hua
To estimate the rate of corneal erosion coupled with gram-negative bacterial contamination of contact lenses and compare this with the rate of microbial keratitis (MK) with contact lenses. The rate of corneal erosion and contact lens contamination by gram-negative bacteria were calculated from several prospective trials. These rates were used to calculate the theoretical rate of corneal erosion happening at the same time as wearing a contact lens contaminated with gram-negative bacteria. This theoretical rate was then compared with the rates of MK reported in various epidemiological and clinical trials. Corneal erosions were more frequent during extended wear (0.6-2.6% of visits) compared with daily wear (0.01-0.05% of visits). No corneal erosions were observed for lenses worn on a daily disposable basis. Contamination rates for lenses worn on a daily disposable basis were the lowest (2.4%), whereas they were the highest for low Dk lenses worn on an extended wear basis (7.1%). The estimated rate of corneal erosions occurring at the same time as wearing lenses contaminated with gram-negative bacteria was the lowest during daily wear of low Dk lenses (1.56/10,000 [95% CI: 0.23-10.57]) and the highest during extended wear of high Dk lenses (38.55/10,000 [95% CI: 24.77-60.04]). These rates were similar in magnitude to the rates reported for MK of different hydrogel lenses worn on differing wear schedules. The coincidence of corneal erosions during lens wear with gram-negative bacterial contamination of lenses may account for the relative incidence of MK during lens wear with different lens materials and modes of use.
Zhu, Zhiling; Li, Siheng; McDermott, Alison M.
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. PMID:28188995
Ji, Yong Woo; Cho, Young Joo; Lee, Chul Hee; Hong, Soon Ho; Chung, Dong Yong; Kim, Eung Kweon; Lee, Hyung Keun
To compare physical characteristics of cosmetic contact lenses (Cos-CLs) and conventional contact lenses (Con-CLs) that might affect susceptibility to bacterial adhesion on the contact lens (CL) surface. Surface characteristics of Cos-CLs and Con-CLs made from the same material by the same manufacturer were measured by atomic force microscopy (AFM) and scanning electron microscopy. To determine the extent and rate of bacterial adhesion, Cos-CL and Con-CL were immersed in serum-free Roswell Park Memorial Institute media containing Staphylococcus aureus or Pseudomonas aeruginosa. Additionally, the rate of removal of adherent bacteria was evaluated using hand rubbing or immersion in multipurpose disinfecting solutions (MPDS). The mean surface roughness (root mean square and peak-to-valley value) measured by AFM was significantly higher for Cos-CL than for Con-CL. At each time point, significantly more S. aureus and P. aeruginosa adhered to Cos-CL than to Con-CL, which correlated with the surface roughness of CL. In Cos-CL, bacteria were mainly found on the tinted surface rather than on the noncolored or convex areas. Pseudomonas aeruginosa attached earlier than S. aureus to all types of CL. However, P. aeruginosa was more easily removed from the surface of CL than S. aureus by hand rubbing or MPDS soaking. Increased surface roughness is an important physical factor for bacterial adhesion in Cos-CL, which may explain why rates of bacterial keratitis rates are higher in Cos-CL users in CL physical characteristics.
AlQattan, Bader; Yetisen, Ali K; Butt, Haider
Contact lenses are ubiquitous biomedical devices used for vision correction and cosmetic purposes. Their application as quantitative analytical devices is highly promising for point-of-care diagnostics. However, it is a challenge to integrate nanoscale features into commercial contact lenses for application in low-cost biosensors. A neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (1064 nm, 3 ns pulse, 240 mJ) in holographic interference patterning mode was utilized to produce optical nanostructures over the surface of a hydrogel contact lens. One-dimensional (925 nm) and two-dimensional (925 nm × 925 nm) nanostructures were produced on contact lenses and analyzed by spectroscopy and angle-resolve measurements. The holographic properties of these nanostructures were tested in ambient moisture, fully hydrated, and artificial tear conditions. The measurements showed a rapid tuning of optical diffraction from these nanostructures from 41 to 48°. The nanostructures were patterned near the edges of the contact lens to avoid any interference and obstruction to the human vision. The formation of 2D nanostructures on lenses increased the diffraction efficiency by more than 10%. The versatility of the holographic laser ablation method was demonstrated by producing four different 2D nanopattern geometries on contact lenses. Hydrophobicity of the contact lens was characterized by contact angle measurements, which increased from 59.0° at pristine condition to 62.5° at post-nanofabrication. The holographic nanostructures on the contact lens were used to sense the concentration of Na + ions. Artificial tear solution was used to simulate the conditions in dry eye syndrome, and nanostructures on the contact lenses were used to detect the electrolyte concentration changes (±47 mmol L -1 ). Nanopatterns on a contact lens may be used to sense other ocular diseases in early stages at point-of-care settings.
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…
Beattie, Tara K; Tomlinson, Alan; Seal, David V; McFadyen, Angus K
Sodium salicylate has shown potential as a component of contact lens care solutions designed to reduce Acanthamoebal attachment to contact lenses. This study determined the minimum effective concentration required to significantly reduce amoebal attachment. Different concentrations of sodium salicylate (10, 15, and 20 mM) were applied during exposure of unworn or bacterial biofilm-coated hydrogel contact lenses to Acanthamoeba castellanii trophozoites. Salicylate was applied at stage 1 intervention during biofilm formation on lenses, at stage 2 intervention during amoebal exposure, or at both stages. A significant reduction in amoebal attachment was achieved when 10 mM salicylate was included during stage 1 alone; however, 15 mM was required for stage 2 intervention to significantly reduce attachment to clean or biofilm-coated lenses. For stages 1 and 2 combined intervention, 10 mM sodium salicylate produced a significant reduction in amoebal attachment. In situ, within a contact lens case, biofilm formation and amoebal attachment would occur concurrently; therefore, stages 1 and 2 intervention would be closest to the real-life situation, thus indicating that 10 mM of salicylate would be an effective minimum concentration for reducing amoebal attachment to hydrogel contact lenses. Inclusion of components in contact lens care solution, such as sodium salicylate, which reduce Acanthamoebal attachment, has the potential to enhance effectiveness, particularly where amoebicidal efficacy may be limited, thus reducing the risk of contact lens-associated Acanthamoebal infection.
Onurdağ, Fatma Kaynak; Ozkan, Semiha; Ozgen, Selda; Olmuş, Hülya; Abbasoğlu, Ufuk
In this study it was aimed to determine the adherence of Pseudomonas and Candida to contact lens surfaces, and to determine the difference in adherence between five contact lens types. Biofilm-negative control strains were also used to emphasize the difference between biofilm-positive and biofilm-negative strains in adherence. Five different soft contact lenses were used to investigate the adherence of Pseudomonas aeruginosa and Candida albicans strains. P. aeruginosa ATCC 27853, P. aeruginosa ATCC 10145, C.albicans ATCC 10231 standard strains and C. albicans clinical isolate were included in the study. Slime formation was investigated by two methods; modified Christensen macrotube method, and a modified microtiter plate test. P. aeruginosa and C. albicans slime formation on soft contact lenses was studied in adherence and separation phases. Pseudomonas and Candida suspensions were serially diluted and inoculated to blood agar and sabouraud dextrose agar surfaces respectively. After overnight incubation, the colonies were counted. Sterile unworn contact lenses were used as negative controls, and bacterial and fungal culture suspensions were used as positive controls. The experiments were conducted in three parallel series. The number of adherent Pseudomonas was as follows from high to low in polymacon, etafilcon A, hilafilcon, ocufilcon and lotrafilcon contact lenses respectively. However, the number of adherent yeast were determined higher in lotrafilcon and ocufilcon contact lenses, followed by hilafilcon, etafilcon A and polymacon contact lenses. Biofilm-negative Pseudomonas ATCC standard strain and Candida clinical isolate were used to confirm that the number of adherent cells were lower than the biofilm-positive ones. This study demonstrates that in addition to the contact lens properties, the microorganisms themselves and their interactions with the lens material also play an important role in adherence.
Donnchadha, Éanna Mac; Leal, Cristina; Esmonde, Harry
The complex modulus of a soft contact lens affects the optical performance, fitting, on-eye movement, wettability, physiological impact and overall comfort of the lens. However, despite acknowledgement that the mechanical behaviour of contact lenses is time-dependent, the rheological characteristics of contact lenses remain under-defined. While existing studies have focussed on elasticity to describe lens behaviour, this paper proposes using oscillatory squeeze film analysis to evaluate the complex modulus. The effects of excitation amplitude, repeatability and surface wetness are examined for four commercially available lenses. Slip at the lens/platen interface is considered along with bias introduced by pre-compressing the lens between platens. Test results when compared to results reported from other test methods indicate that a high degree of slip occurs at the lens platen interface suggesting that deformation is primarily due to biaxial extension. Copyright © 2018 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
The typical distinguishing features of special cases which require contact lenses for satisfactory vision are described. Hence in the first case with anisometria associated with irregular astigmatism of one eye, to which a toric soft contact lens was adapted. In the second case a visual acuity of only 0,6 monocular was attained with the best spectacle lens, however with contact lense the visual acuity was 1.25. Here a verdict from a social court is mentioned, which obliged the sickness insurance to take over the costs for such a case. In the third case the adaptation of contact lenses was undertaken after radical bilateral keratoplasty because of parenchymatous keratitis, and an improvement in visual acuity of at least 400% resulted.
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.
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.
Ticak, Anita; Walline, Jeffrey J
To determine whether bifocal soft contact lenses with a distance center design provide myopic defocus to the peripheral retina similar to corneal reshaping contact lenses. Myopic subjects underwent five cycloplegic autorefraction readings centrally and at 10, 20, and 30 degrees temporally, nasally, superiorly, and inferiorly while wearing Proclear Multifocal "D" contact lenses with a +2.00-diopter add power (CooperVision, Fairport, NY) and after wearing Corneal Refractive Therapy (Paragon Vision Sciences, Mesa, AZ) contact lenses for 2 weeks. Fourteen subjects completed the study. Nine (64%) were female, and 12 (86%) were white. The average (± SD) spherical equivalent noncycloplegic manifest refraction for the right eye was -2.84 ± 1.29 diopters. The average logMAR best-corrected, binocular, high-contrast visual acuity was -0.17 ± 0.15 while wearing the bifocal soft contact lenses and -0.09 ± 0.16 after corneal reshaping contact lens wear (analysis of variance, p = 0.27). The orthokeratology contact lens yielded a more myopic peripheral optical profile than the soft bifocal contact lens at 20 and 30 degrees eccentricity (except inferior at 20 degrees); the two modalities were similar at 10 degrees eccentricity. Our data suggest that the two modalities are dissimilar despite the statistical similarities. The corneal reshaping contact lens shows an increase in relative peripheral myopic refraction, a pattern achieved by other studies, but the bifocal lens does not exhibit such a pattern. The low statistical power of the study could be a reason for lack of providing statistical difference in other positions of gaze, but the graphical representation of the data shows a marked difference in the peripheral optical profile between the two modalities. More sophisticated methods of measuring the peripheral optical profile may be necessary to accurately compare the two modalities and to determine the true optical effect of the bifocal soft contact lens on the peripheral
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 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Belda-Salmerón, Lurdes; Madrid-Costa, David; Ferrer-Blasco, Teresa; García-Lázaro, Santiago; Montés-Micó, Robert
To evaluate and compare the distribution of refractive power within the optic zone of different soft contact lenses and to investigate the effect of lens decentration on the power profiles. The Nimo TR1504 instrument was used to measure the optical power across different aperture diameters (from 1.5mm to 5.5mm in steps of 0.5mm) of four daily disposable contact lenses: DAILIES TOTAL1, Proclear 1-Day, SofLens daily disposable and 1-DAY ACUVUE MOIST. Measurements were performed using a wet cell. Power data were evaluated when contact lenses were in its centered position and after inducing different amounts of lens decentration (from 0.2mm to 1.0mm in steps of 0.2mm). All contact lenses showed an increase - more negative - in lens power with distance from the lens center. The amount of change varied depending on the lens. It was about 10% of lens power for DAILIES TOTAL1 (-0.29diopters (D)), SofLens daily disposable (-0.36D), and Proclear 1-Day (-0.32D) whereas 1-DAY ACUVUE MOIST showed a percentage variation of 3.3% (-0.10D). After inducing a lens decentration up to 1mm, the power curves were shifted in the negative direction. However, the change obtained in lens power compared with well-centered position was always lower than a quarter of diopter both for all the lenses and aperture diameters. Our results showed a variation of the refractive power from the lens center, becoming more negative toward the periphery, with a negligible effect of the decentration for all disposable contact lenses studied. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
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
Stapleton, Fiona; Keay, Lisa; Edwards, Katie; Holden, Brien
It was widely anticipated that after the introduction of silicone hydrogel lenses, the risk of microbial keratitis would be lower than with hydrogel lenses because of the reduction in hypoxic effects on the corneal epithelium. Large-scale epidemiological studies have confirmed that the absolute and relative risk of microbial keratitis is unchanged with overnight use of silicone hydrogel materials. The key findings include the following: (1) The risk of infection with 30 nights of silicone hydrogel use is equivalent to 6 nights of hydrogel extended wear; (2) Occasional overnight lens use is associated with a greater risk than daily lens use; (3) The rate of vision loss due to corneal infection with silicone hydrogel contact lenses is similar to that seen in hydrogel lenses; (4) The spectrum of causative organisms is similar to that seen in hydrogel lenses, and the material type does not impact the corneal location of presumed microbial keratitis; and (5) Modifiable risk factors for infection include overnight lens use, the degree of exposure, failing to wash hands before lens handling, and storage case hygiene practice. The lack of change in the absolute risk of disease would suggest that exposure to large number of pathogenic organisms can overcome any advantages obtained from eliminating the hypoxic effects of contact lenses. Epidemiological studies remain important in the assessment of new materials and modalities. Consideration of an early adopter effect with studies involving new materials and modalities and further investigation of the impact of second-generation silicone hydrogel materials is warranted.
Almesmary, A A
In the clinical practice we have met with the fact that some patients did not tolerate soft coloured contact lenses even when they used them for a short time. To find whether the cause is the composition of these lenses, mainly the adding of stain, he used the laboratory test to determine cytotoxicity, the test of dynamic observation of cytotoxicity where the cells cultured in vitro are the experimental object. On the basis of the results of this test commonly used for the determination of the cytotoxicity of implantation materials, he thinks that the cause of intolerance of coloured lenses is not their toxicity but other phenomena. An individual hypersensitivity or insufficient care of lenses (the influence of disinfectants) can be among these causes.
Subbaraman, Lakshman N; Borazjani, Roya; Zhu, Hua; Zhao, Zhenjun; Jones, Lyndon; Willcox, Mark D P
The aim of the study is to determine the adhesion of Gram positive and Gram negative bacteria onto conventional hydrogel (CH) and silicone hydrogel (SH) contact lens materials with and without lysozyme, lactoferrin, and albumin coating. Four lens types (three SH-balafilcon A, lotrafilcon B, and senofilcon A; one CH-etafilcon A) were coated with lysozyme, lactoferrin, or albumin (uncoated lenses acted as controls) and then incubated in Staphylococcus aureus (Saur 31) or either of two strains of Pseudomonas aeruginosa (Paer 6294 and 6206) for 24 h at 37 °C. The total counts of the adhered bacteria were determined using the H-thymidine method and viable counts by counting the number of colony-forming units on agar media. All three strains adhered significantly lower to uncoated etafilcon A lenses compared with uncoated SH lenses (p < 0.05). Lysozyme coating on all four lens types increased binding (total and viable counts) of Saur 31 (p < 0.05). However, lysozyme coating did not influence P. aeruginosa adhesion (p > 0.05). Lactoferrin coating on lenses increased binding (total and viable counts) of Saur 31 (p < 0.05). Lactoferrin-coated lenses showed significantly higher total counts (p < 0.05) but significantly lower viable counts (p < 0.05) of adhered P. aeruginosa strains. There was a significant difference between the total and viable counts (p < 0.05) that were bound to lactoferrin-coated lenses. Albumin coating of lenses increased binding (total and viable counts) of all three strains (p < 0.05). Lysozyme deposited on contact lenses does not possess antibacterial activity against certain bacterial strains, whereas lactoferrin possess an antibacterial effect against strains of P. aeruginosa.
Colomé-Campos, J; Quevedo-Junyent, L; Godoy-Barreda, N; Martínez-Salcedo, I; Romero-Aroca, P
To describe the benefits and optimum use of prophylactic antibiotics in users of therapeutic contact lenses (TCL). A microbiological study was carried out on samples from 33 patients who continuously wore TCL. The resistance to antibiotics of bacteria isolated in our health region was also reviewed. An assessment was also made on whether there were microorganisms of a higher pathogenic potential in TCL than conventional contact lenses, as reported in the literature. No bacteria were isolated from 17 (52%) of the 33 lenses studied. From the 16 (48%) remaining lenses, coagulase negative Staphylococci were isolated from 10 (62%), Propionibacterium acnes from 4 (25%), and Corynebacterium from 2 (13%). The high number of negative cultures and the presence of saprophytic bacteria indicate that prophylactic antibiotic treatment is not precise. The most frequent pathogenic bacteria found in contact lenses are strongly resistant to the current commercially available antibiotics. Copyright © 2012 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.
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). [69 FR 40511, July 2, 2004] ...
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.
ben Yaish, Shai; Zlotnik, Alex; Limon, Ofer; Lahav Yacouel, Karen; Doron, Ravid; Zalevsky, Zeev
In this communication we present the first dispensing medical trial in which we successfully report on testing of novel extended depth of focus rigid gas permeable (RGP) contact lenses having reduced halo and distinct focal peaks for near and far distance vision.
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.
Papas, Eric B; Tilia, Daniel; Tomlinson, Daniel; Williams, Josh; Chan, Eddy; Chan, Jason; Golebiowski, Blanka
To establish whether increased end-of-day discomfort during soft contact lens wear is associated with short-term changes occurring to the lens itself. Twenty-seven subjects wore hydrogel lenses (Focus Dailies; Alcon) bilaterally for 10 hours on two separate days. Comfort was reported using 1-100 numerical rating scales (1 = intolerable discomfort, 100 = lens cannot be felt). Day 1 ratings were taken before lens insertion and at 0.05, 5, and 10 hours post-insertion. Day 2 ratings occurred at similar times, but lenses were removed after the 5-hour assessment and either reinserted (n = 14) or newly replaced (n = 12). An additional rating was taken 5 minutes after re-insertion. Wear then continued to the 10-hour point. In a separate study, 24 different subjects repeated these procedures using a silicone hydrogel lens (AirOptix Aqua; Alcon) with wear taking place on 3 days to permit lens replacement to be with existing as well as new lenses in all subjects. For hydrogel lenses, comfort scores (mean ± 95% CI) reported after 10 hours were 79.4 ± 8.3 when lenses were worn un-replaced, compared with 73.2 ± 9.2 for replacement with the existing lens. When replacement was with a brand new lens, the corresponding values were 72.9 ± 10.9 (un-replaced) versus 69.2 ± 12.8 (new lens replacement). For silicone hydrogel lenses, 10-hour comfort was 90.3 ± 3.2 (un-replaced) versus 92.2 ± 2.9 (replacement with existing lens) versus 90.0 ± 3.3 (replacement with new lens). Differences between replacement conditions were not significant in any case (analysis of variance, p > 0.05). Final comfort was not influenced by replacing lenses midway through the wearing period. Comfort decrements experienced by users of these daily contact lenses towards the later part of the wearing period are not caused by changes occurring to the lenses on this time scale. Possible alternative etiological factors include a fatigue-like response in one or more ocular tissues or stimulation of ocular
Harris, M G
Practitioners must understand their legal responsibilities in fitting minors with contact lenses, which include informed consent, contractual obligations, and the Statute of Limitations. Minors are children and teenagers who have not yet reached voting age in their state--generally 18 years of age. Informed consent requires permission from the patient before a practitioner performs any treatment. For these young people, this consent generally can only be given by a parent or legal guardian. Minors can repudiate contracts made with them; therefore, the contractual obligation to pay for a contact lens fitting should be established with a parent or legal guardian. In most states, minors have additional time beyond the usual Statute of Limitations to bring a lawsuit. If practitioners recognize their legal responsibilities in caring for these special patients, fitting youngsters with contact lenses can be a rewarding part of practice.
Harris, M.G.; Rechberger, J.; Grant, T.
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 survivedmore » 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.« less
Hart, D E
SEM was used to visualize tear-film/hydrogel polymer surface interactions. Lenses were preserved by fixation including a quaternary ammonium complex to aid in mucin preservation. In less than 2 weeks of continuous wear the anterior surface was completely coated, yet the coating was absent from the posterior lens surface. Tear-film break-up over the deposited lens surface, combined with degradation and deformation at the polymer surface boundary, as well as entrapment of moieties within the polymer matrix, all occurred. These are the likely culprits which can contribute to adverse reactions as well as cause light scatter and diminished vision. Lenses removed directly from the eyes of patients suffering with different forms of conjunctivitis were obtained. Bacterial and viral conjunctivitis can induce a microbially contaminated as well as a heavily deformed and deposited lens. Viable and intact microbes were not typically observed in the mucoprotein layer of hydrogel 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
Kim, Dong Ju; Park, Joo-Hee; Kim, Marth; Park, Choul Yong
To investigate the antibiofilm efficacy of nitric oxide (NO) on soft contact lenses. Nitrite (NO precursor) release from various concentrations (0-1000 μM) of sodium nitrite (NaNO 2, NO donor) was measured by Griess Assay. Cell viability assay was performed using human corneal epithelial cell under various concentration (0-1000 μM) of NaNO 2 . Biofilm formation on soft contact lenses was achieved by adding Staphylococcus aureus or Pseudomonas aeruginosa to the culture media. Various concentrations of NaNO 2 (0-1000 μM) were added to the culture media, each containing soft contact lens. After incubation in NaNO 2 containing culture media for 1, 3, or 7 days, each contact lens was transferred to a fresh, bacteria-free media without NaNO 2 . The bacteria in the biofilm were dispersed in the culture media for planktonic growth. After reculturing the lenses in the fresh media for 24 h, optical density (OD) of media was measured at 600 nm and colony forming unit (CFU) was counted by spreading media on tryptic soy agar plate for additional 18 h. Nitrite release from NaNO 2 showed dose-dependent suppressive effect on biofilm formation. Most nitrite release from NaNO 2 tended to occur within 30 min. The viability of human corneal epithelial cells was well maintained at tested NaNO 2 concentrations. The bacterial CFU and OD showed dose-dependent decrease in the NaNO 2 treated samples on days 1, 3 and 7 for both Staphylococcus aureus and Pseudomonas aeruginosa. NO successfully inhibited the biofilm formation by Staphylococcus aureus or Pseudomonas aeruginosa on soft contact lenses in dose-dependent manner.
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.
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.
Ticak, Anita; Walline, Jeffrey J.
Purpose To determine whether bifocal soft contact lenses with a distance center design provide myopic defocus to the peripheral retina similar to corneal reshaping contact lenses. Methods Myopic subjects underwent five cycloplegic autorefraction readings centrally and at 10, 20, and 30 degrees temporally, nasally, superiorly, inferiorly while wearing a Proclear Multifocal “D” contact lens with a +2.00 D add (CooperVision, Fairport, NY) and after wearing a Corneal Refractive Therapy (Paragon Vision Sciences, Mesa, AZ) contact lens for two weeks Results Fourteen subjects completed the study. Nine (64%) were female, and 12 (86%) were Caucasian. The average (± standard deviation) spherical equivalent non-cycloplegic manifest refraction for the right eye was −2.84 ± 1.29 D. The average logMAR best-corrected, binocular high contrast visual acuity was −0.17 ± 0.15 while wearing the bifocal soft contact lens, and −0.09 ± 0.16 following corneal reshaping contact lens wear (ANOVA, p = 0.27). The orthokeratology contact lens yielded a more myopic peripheral optical profile than the soft bifocal contact lens at 20 and 30 degrees eccentricity (except inferior at 20 degrees); the two modalities were similar at 10 degrees eccentricity. Conclusions Our data suggest that the two modalities are dissimilar despite the statistical similarities. The corneal reshaping contact lens shows an increase in relative peripheral myopic refraction, a pattern achieved by other studies, but the bifocal lens does not exhibit such a pattern. The low statistical power of the study could be a reason for a lack of providing statistical difference in other positions of gaze, but the graphical representation of the data shows a marked difference in peripheral optical profile between the two modalities. More sophisticated methods of measuring the peripheral optical profile may be necessary to accurately compare the two modalities and to determine the true optical effect of the bifocal soft
Gong, Celia R; Troilo, David; Richdale, Kathryn
Purpose To determine the effect of multifocal contact lenses on accommodation and phoria in children. Methods 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 4 distances (>3m, 100cm, 40cm, 25cm). 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. Results A total of 16 subjects, aged 10-15 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<0.01) visual acuity, and contrast sensitivity (SV: 2.0, MF: 1.9 log units, p=0.015) with multifocals. Subjects were more exophoric at 40 cm (SV: -0.41, MF: -2.06 Δ) and 25cm (SV: -0.83, MF: -4.30 Δ) (both p<0.01). With multifocals, subjects had decreased accommodative responses at distance (SV: -0.04; MF: -0.37 D, p=0.02), 100 cm (SV: +0.37; MF: -0.35 D, p<0.01), 40 cm (SV: +1.82; MF: +0.62 D, p<0.01), and 25 cm (SV: +3.38; MF: +1.75 D, p<0.01). There were no significant differences in accommodative amplitude (p=0.66) or facility (p=0.54). Conclusions 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
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
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.
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
Denk, Nora; Fritsche, Jens; Reese, Sven
To evaluate the effect of UV-blocking soft contact lenses in treatment for chronic superficial keratitus (CSK). Twenty six dogs with CSK were treated continuously with UV-blocking contact lenses for 6 months. A contact lens was placed on one eye of each dog; the other eye remained without a lens as a control eye. After this primary study, five of the dogs were further treated and they wore then contact lenses in both eyes. Continuously, all patients were concurrently treated topically with cyclosporine. The contact lenses were changed every 4 weeks and an ophthalmic examination performed. Evaluation criteria included corneal alterations as pigmentation, edema, pannus and vascularization. To determine the transmittance characteristics of the contact lenses before and after use, 32 contact lenses were measured with a UV-vis-NIR spectrophotometer. Pigmentation increased in eyes wearing lenses and in control eyes over the evaluation period of 6 months. Corneal edema increased in the eyes wearing lenses, but remained unaffected in the control eyes. A significant difference in the incidence of pannus and the extent of corneal vascularisation could not be evaluated. Adverse effects were noted in six cases (corneal edema and vascularisation, conjunctivitis, blepharospasm). All new lenses studied reduced UV-radiation to a safe level, whereas used lenses did not maintain their transmittance characteristics. No positive effect of UV-blocking contact lenses could be proven with the study design used. © 2011 American College of Veterinary Ophthalmologists.
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
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
Sivardeen, Ahmed; Laughton, Deborah; Wolffsohn, James S
To assess the performance of four commercially available silicone hydrogel multifocal monthly contact lens designs against monovision. A double-masked randomized crossover trial of Air Optix Aqua multifocal, PureVision 2 for Presbyopia, Acuvue OASYS for Presbyopia, Biofinity multifocal, and monovision with Biofinity contact lenses was conducted on 35 presbyopes (54.3 ± 6.2 years). After 4 weeks of wear, visual performance was quantified by high- and low-contrast visual acuity under photopic and mesopic conditions, reading speed, defocus curves, stereopsis, halometry, aberrometry, Near Activity Visual Questionnaire rating, and subjective quality of vision scoring. Bulbar, limbal, and palpebral hyperemia and corneal staining were graded to monitor the impact of each contact lens on ocular physiology. High-contrast photopic visual acuity (p = 0.102), reading speed (F = 1.082, p = 0.368), and aberrometry (F = 0.855, p = 0.493) were not significantly different between presbyopic lens options. Defocus curve profiles (p < 0.001), stereopsis (p < 0.001), halometry (F = 4.101, p = 0.004), Near Activity Visual Questionnaire (F = 3.730, p = 0.007), quality of vision (p = 0.002), bulbar hyperemia (p = 0.020), and palpebral hyperemia (p = 0.012) differed significantly between lens types, with the Biofinity multifocal lens design principal (center-distance lens was fitted to the dominant eye and a center-near lens to the nondominant eye) typically outperforming the other lenses. Although ocular aberration variation between individuals largely masks the differences in optics between current multifocal contact lens designs, certain design strategies can outperform monovision, even in early presbyopes.
Freeman, M I
At the present time, nine lathe-cut lenses are FDA approved and commercially available in the United States. Complications of lathe-cut soft contact lenses cover a wide spectrum of problems. Five significant complications of lathe-cut lenses and their prevention and therapeutic management are discussed.
Collins, Randall S; McChesney, Megan E; McCluer, Craig A; Schatz, Martha P
The efficacy of opaque contact lenses as occlusion therapy for amblyopia has been established in the literature. Prosthetic contact lenses use similar tints to improve cosmesis in scarred or deformed eyes and may be an alternative in occlusion therapy. To test this idea, we determined the degree of vision penalization elicited by prosthetic contact lenses and their effect on peripheral fusion. We tested 19 CIBA Vision DuraSoft 3 Prosthetic soft contact lenses with varying iris prints, underprints, and opaque pupil sizes in 10 volunteers with best-corrected Snellen distance visual acuity of 20/20 or better in each eye. Snellen visual acuity and peripheral fusion using the Worth 4-Dot test at near were measured on each subject wearing each of the 19 lenses. Results were analyzed with 3-factor analysis of variance. Mean visual acuity through the various lenses ranged from 20/79 to 20/620. Eight lenses allowed preservation of peripheral fusion in 50% or more of the subjects tested. Iris print pattern and opaque pupil size were significant factors in determining visual acuity (p < 0.05). Sufficient vision penalization can be achieved to make occlusion with prosthetic contact lenses a viable therapy for amblyopia. The degree of penalization can be varied and different iris print patterns and pupil sizes, using peripheral fusion, can be preserved with some lenses. Prosthetic contact lenses can be more cosmetically appealing and more tolerable than other amblyopia treatment modalities. These factors may improve compliance in occlusion therapy.
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.
Dutta, Debarun; Willcox, Mark DP
Adhesion of pathogenic microbes, particularly bacteria, to contact lenses is implicated in contact lens related microbial adverse events. Various in vitro conditions such as type of bacteria, the size of initial inoculum, contact lens material, nutritional content of media, and incubation period can influence bacterial adhesion to contact lenses and the current study investigated the effect of these conditions on bacterial adhesion to contact lenses. There was no significant difference in numbers of bacteria that adhered to hydrogel etafilcon A or silicone hydrogel senofilcon A contact lenses. Pseudomonas aeruginosa adhered in higher numbers compared to Staphylococcus aureus. Within a genera/species, adhesion of different bacterial strains did not differ appreciably. The size of initial inoculum, nutritional content of media, and incubation period played significant roles in bacterial adhesion to lenses. A set of in vitro assay conditions to help standardize adhesion between studies have been recommended. PMID:24833224
Campbell, Darren; Carnell, Sarah Maria; Eden, Russell John
Contact angle, as a representative measure of surface wettability, is often employed to interpret contact lens surface properties. The literature is often contradictory and can lead to confusion. This literature review is part of a series regarding the analysis of hydrogel contact lenses using contact angle techniques. Here we present an overview of contact angle terminology, methodology, and analysis. Having discussed this background material, subsequent parts of the series will discuss the analysis of contact lens contact angles and evaluate differences in published laboratory results. The concepts of contact angle, wettability and wetting are presented as an introduction. Contact angle hysteresis is outlined and highlights the advantages in using dynamic analytical techniques over static methods. The surface free energy of a material illustrates how contact angle analysis is capable of providing supplementary surface characterization. Although single values are able to distinguish individual material differences, surface free energy and dynamic methods provide an improved understanding of material behavior. The frequently used sessile drop, captive bubble, and Wilhelmy plate techniques are discussed. Their use as both dynamic and static methods, along with the advantages and disadvantages of each technique, is explained. No single contact angle technique fully characterizes the wettability of a material surface, and the application of complimenting methods allows increased characterization. At present, there is not an ISO standard method designed for soft materials. It is important that each contact angle technique has a standard protocol, as small protocol differences between laboratories often contribute to a variety of published data that are not easily comparable.
Astigmatism 1 I Accommodation and Convergence 12 Advantages and Disadvantages of Contact Lenses 12 Optical Performance 12 Compliance 13 Supervision 13...absence of parallel tear lens, especially advantages of dealing with only one type of lens and accompanying astigmatism ) support system. - discomfort...Polcon I low. provides an explanation for the failure of high Dk Potycon 1I 8 a materials in fitting a cornea with astigmatism and the Si-02-•• ex need
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.
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.
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.
Schmäl, F; Stoll, W
During electronystagmography it is necessary to correct detective vision for calibration, smooth pursuit, and saccadic eye movements. Therefore more and more people use contact lenses instead of normal glasses. Given the lack of detailed information about this phenomenon, in the current literature we decided to investigate the influence of soft contact lenses on electronystagmography. The aim of this study was to find out differences in the results of electronystagmography between using glasses or contact lenses. Our investigation involved 20 vestibular healthy human subjects with myopia. In the first part of the examination they used their contact lenses and in the second part they were wearing normal glasses. After measuring the calibration potential we wanted to see if contact lenses would increase the rate of artifacts in the electronystagmogram. Then we attempted to determine whether contact lenses would an influence on the registration of the optokinetic nystagmus. Induced saccadic eye movements were recorded and analysed. Contact lenses had a negative influence neither on the calibration potential nor on the rate of artifacts. The latency of the saccadic eye movements also showed no differences between both parts of this investigation. Only the velocity of the saccades and the gain value during the optokinetic test were reduced when glasses were used. Contact lenses may stimulate the secretory function of the lacrimal gland and thus decrease friction forces. It is also possible that the reduced image size produced or the reduction-effect of minus by glasses in near sighted persons negatively influences eyeball velocity. In summary, our study demonstrates that contact lenses do not have a negative influence on electronystagmography. Therefore electronystagmographic studies of patients with contact lenses are permissible for purposes of documenting a medical opinion.
Lackner, Birgit; Pieh, Stefan; Schmidinger, Gerald; Hanselmayer, Georg; Dejaco-Ruhswurm, Irene; Funovics, Martin A; Skorpik, Christian
To evaluate long-term results after insertion of implantable contact lenses (ICLs) in phakic eyes. Prospective, noncomparative, interventional case series. Seventy-five phakic eyes (65 myopic, 10 hyperopic eyes) of 45 patients aged 21.7 to 60.6 years were included. STAAR Collamer Implantable Contact Lenses (STAAR Surgical Inc., Nidau, Switzerland) were implanted for correction of high myopia and hyperopia. Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), and intraocular pressure (IOP) were determined. Presence of lens opacification and the distance between the ICL and the crystalline lens were assessed by slit-lamp examination before surgery and at 1, 3, 6 months, and yearly after lens implantation. Preoperative mean spherical equivalent was -16.23+/-5.29 diopters (D) for myopic eyes and +7.88 +/-1.46 D for hyperopic eyes. After ICL implantation, mean residual refractive error was -1.77+/-2.17 D in myopic patients and +0.44+/-0.69 D in hyperopic patients. Preoperative mean UCVA was Snellen 0.03+/-0.03 for myopic patients and Snellen 0.12+/-0.16 for hyperopic patients. Preoperative mean BCVA was Snellen 0.49+/-0.23 for myopic patients and Snellen 0.82+/-0.23 for hyperopic patients. After ICL implantation, mean UCVA up to the end of individual observation time was Snellen 0.36+/-0.36 for myopic patients and Snellen 0.58+/-0.28 for hyperopic patients. Mean BCVA was Snellen 0.73+/-0.26 for myopic and Snellen 0.80+/-0.24 for hyperopic patients. Mean preoperative IOP was 14.2+/-2.7 mmHg, and mean postoperative IOP was 13.46+/-2.1 mmHg over all follow-up investigations. The main complication was the development of subcapsular anterior opacifications of the crystalline lens in 25 eyes (33.3%), 2 of which showed direct contact to the ICL. Eleven eyes (14.7%) were stable in opacification and 14 eyes (18.7%) had progressive opacifications. The median time to opacification was 27.1 months. In 8 patients (10.7%), the subjective visual impairment mandated
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.
Sorbara, L; Jones, L; Williams-Lyn, D
To describe the refitting of a soft lens wearer into a silicone hydrogel lens due to neovascularization. This change, in turn, caused contact lens induced papillary conjunctivitis (CLPC) and a further refitting was necessary. The patient was refit into a high Dk surface treated silicone hydrogel with a high modulus value. A second refitting was undertaken into a lower Dk silicone hydrogel contact lens with a lower modulus value which had no surface treatment but incorporated an internal wetting agent. A high Dk/t lens was used to resolve existing neovascularization and chronic hyperaemia. Subsequently, CLPC response occurred, possibly due to a combination of factors, resulting in irritation of the palpebral conjunctiva. This resulted in temporary lens discontinuation. A second silicone hydrogel lens was fit, along with the use of a non-preserved care system, which led to improvement and eventual resolution of the condition. High Dk silicone hydrogel lenses have shown excellent efficacy in resolving hypoxic complications such as neovascularization and hyperaemia. However, attention needs to be paid to their potential effect on the upper tarsal plate. More than one silicone hydrogel lens may be needed to help resolve these issues.
Bilgihan, Kamil; Yuksel, Erdem; Deniz, Nuriye Gokcen; Yuksel, Nilay
Corneal collagen cross linking (CCL) with ultraviolet A (UVA) has been proposed as a treatment for the progression of corneal ectasia associated with keratoconus and post-laser-assisted in situ keratomileusis (LASIK) ectasia. Despite the reports about safety of procedure, we consider that UVA of sunlight can effect riboflavin saturated and de-epitelizated cornea early after CCL. To evaluate the UVA blockage capability of 11 different silicone hydrogel contact lenses which are widely used after CCL treatment. Eleven different silicone hydrogel and daily disposable contact lenses were evaluated. The UVA light at 365 nm wavelength for UVA source and UV light meter to measure UVA radiation were used. 3, 9 and 18 mW/cm(2) power of UV radiance was applied centrally to the each type of contact lenses. The power of UVA transmittance for each radiance and percentage of blockage were evaluated for each brand. Also, protection factor (PF) was calculated. The senofilcon A and narafilcon A had the highest blockage and lowest transmittance (p = 0.02). PF was significantly higher in the senofilcon A and narafilcon A at 3, 9 and 18 mW/cm(2) (p = 0.0001). And also, the hilafilcon B, filcon IV, nelfilcon A, enfilcon A, lotrafilcon A and lotrafilcon B had the highest UVA transmittance. The narafilcon A and the senofilcon A may be a good options for epithelial healing after CCL procedure to protect the cornea from UVA of sunlight. And also, the hilafilcon B, filcon IV, nelfilcon A, enfilcon A, lotrafilcon A and lotrafilcon B contact lenses that have high-UVA transmittance feature can be a treatment choice for contact lens-assisted CCL technique in thin corneas.
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.
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.
Thakur, Deeksha V.; Gaikwad, Ujjwala N.
Background & objectives: With increasing use of soft contact lenses the incidence of contact lens induced infections is also increasing. This study was aimed to assess the knowledge of new and existing contact lens users about the risk of microbial contamination associated with improper use and maintenance of contact lenses, type of microbial flora involved and their potential to cause ophthalmic infections. Methods: Four samples each from 50 participants (n=200) were collected from the lenses, lens care solutions, lens care solution bottles and lens cases along with a questionnaire regarding their lens use. The samples were inoculated onto sheep blood agar, Mac Conkey's agar and Sabouraud's dextrose agar. Organisms were identified using standard laboratory protocols. Results: Overall rate of microbial contamination among the total samples was 52 per cent. The most and the least contaminated samples were found to be lens cases (62%) and lens care solution (42%), respectively. The most frequently isolated contaminant was Staphylococcus aureus (21%) followed by Pseudomonas species (19.5%). Majority (64%) of the participants showed medium grade of compliance to lens cleaning practices. Rate of contamination was 100 and 93.75 per cent respectively in those participants who showed low and medium compliance to lens care practices as compared to those who had high level of compliance (43.75%) (P<0.05). Interpretation & conclusions: Lens care practices amongst the participants were not optimum which resulted into high level contamination. Hence, creating awareness among the users about the lens care practices and regular cleaning and replacements of lens cases are required. PMID:25297366
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.
Chiericati, Stefano; Borghesi, Alessandro; Cozza, Federica; Ferraro, Lorenzo; Acciarri, Maurizio; Farris, Stefano; Tavazzi, Silvia
This article compares the optical performance of soft contact lenses (CLs) treated with multipurpose or hydrogen peroxide care systems. The investigated care systems were (1) 3% hydrogen peroxide solution Oxysept (Abbot Medical Optics, Abbott Park, IL) and (2) multipurpose solution Regard (Vita Research, Ariccia, Italy). Three types of silicone hydrogel CLs were studied (comfilcon A, lotrafilcon B, and balafilcon A), unworn and exposed for 30 times to the solutions, which were replaced every 8 hr. The optical performance of the CLs was evaluated through the on-eye transmitted light wavefront patterns by considering new CLs as references. The surface morphology of the CLs was investigated by scanning electron microscopy. Statistically significant modifications in the range 0.1 to 0.3 μm of Zernicke coefficients and modifications of the root mean square of the wavefront aberration function were found for CLs treated with multipurpose solution, in agreement with the observed modifications of the surface morphology. Statistically significant changes were also found after exposure to the hydrogen peroxide solution, but the variation of the Zernicke coefficients was found lower than 0.1 μm, thus being negligible in CL optical performances. In addition to disinfection ability and ocular surface reactions, CL care systems are different in solution-related CL optical performance. Multipurpose solutions may affect the CL surface morphology with significant modifications of the transmitted light wavefront pattern.
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.
Bandara, Mahesh K; Masoudi, Simin; Zhu, Hua; Bandara, Rani; Willcox, Mark D P
To investigate the ability of protamine, alone or in combination with other antimicrobial agents, to kill bacteria and fungi associated with contact lens-related keratitis. The International Organization for Standardization 14729:2001 procedure was used to test the antimicrobial activity of solutions of protamine (23-228 μM) with and without polyhexamethylene biguanide (PHMB) and ethylenediamine tetra-acetic acid (EDTA). The recommended ISO panel of microbes along with six clinical isolates was tested. The effect of increasing sodium chloride concentration on the antimicrobial activity was also assessed. The cytotoxicity of the final protamine/EDTA/PHMB solution was measured using ISO 10993-5 standard assays. Protamine gave a dose-dependent antimicrobial effect, with the highest effect for most strains being at 228 μM (≥6 log reductions of viable bacteria and ≥1 log reduction of viable fungi). Addition of EDTA and PHMB increased the antimicrobial effect for all strains except Pseudomonas aeruginosa ATCC6538, which had optimum activity (≥6 log inhibition) even in protamine alone. The optimum antimicrobial activity of all microbes was achieved in 0.2% sodium chloride, but even in 0.8% sodium chloride, the activity met or exceeded the ISO standard (>3 log reductions for bacteria and >1 log reduction for fungi). None of the formulations was cytotoxic to mammalian cells. This study highlights the potential for protamine to be used for the development of effective multipurpose disinfection solutions. Further investigations such as stability, compatibility with contact lenses, and in vivo toxicity are warranted.
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.
Draeger, J; Schröder, U; Vogt, L
It is still forbidden by German law for cockpit aircrew to wear contact lenses. This is due in particular to experience gathered in the past with older types of contact lenses, especially those made of glass or PMMA. Meanwhile, technological progress has brought improvements in respect of material, size, tolerance and particularly the optical result. Investigations were carried out with regard to the tolerance of contact lenses in condition of low humidity, high g and sudden compression. The results are given and the consequences for cockpit aircrew and passengers are discussed.
Tseng, Santos Shan-Yu; Yang, Winston Wen-Ching; Hsiao, John Ching-Jen
We report a case demonstrating the importance of trial fitting before the dispensing of prescription contact lenses. The patient was an 18-year-old computer-using experienced hydrogel lens wearer who ran out of contact lens supply. The patient purchased a brand new box of daily disposable lenses from a retail store having known his back vertex power. No trial fitting of the lenses was performed at the point of sale. After a day of wear of the lenses with significant computer use, the patient removed them and went to bed, but the next morning, presented on an emergency basis with severe pain and blurry vision in both eyes. Slit lamp examination showed significant bilateral corneal erosions that were treated with prophylactic antibiotics, steroids, and lubricants. A bandage contact lens was further given to his right eye. The characteristics of the daily disposable lenses and his computer overuse were viewed as contributing factors to the complication. The dispensing and wear of prescription contact lenses without a proper selection and fit led to bilateral corneal erosions in this patient. Though our case occurred in Taiwan, a jurisdiction where prescription contact lens sale is not regulated, the authors note that such a scenario could occur in jurisdictions where contact lens sale is regulated if, after confirmation of back vertex power, no effort is made to ensure that a purchased lens is safe or appropriate for a patient, such as when lenses are purchased through internet suppliers or in certain commercial retail settings.
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.
Altoaimi, Basal H; Almutairi, Meznah S; Kollbaum, Pete S; Bradley, Arthur
The effectiveness of multifocal contact lenses (MFCLs) at slowing myopia progression may hinge on the accommodative behavior of young eyes fit with these presbyopic style lenses. Can they remove hyperopic defocus? Convergence accommodation as well as pupil size and the zonal geometry are likely to contribute to the final accommodative responses. The aim of this study was to examine the accommodation behavior of young adult eyes wearing MFCLs and the effectiveness of these MFCLs at removing foveal hyperopic defocus when viewing near targets binocularly. Using a high-resolution Shack-Hartmann aberrometer, accommodation and pupil behavior of eight young adults (27.25 ± 2.05 years) were measured while subjects fixated a 20/40 character positioned between 2 m and 20 cm (0.50 to 5.00 diopters [D]) in 0.25-D steps. Refractive states were measured while viewing binocularly and monocularly with single-vision and both center-distance and center-near +2.00 D add MFCLs. Refractive state was defined using three criteria: the dioptric power that would (1) minimize the root mean square wavefront error, (2) focus the pupil center, and (3) provide the peak image quality. Refractive state pupil maps reveal the complex optics that exist in eyes wearing MFCLs. Reduced accommodative gain beyond the far point of the near add revealed that young subjects used the added plus power to help focus near targets. During accommodation to stimuli closer than the far point generated by the add power, a midperipheral region of the pupil was approximately focused, resulting in the smallest accommodative errors for the minimum root mean square-defined measures of refractive state. Paraxial images were always hyperopically or myopically defocused in eyes viewing binocularly with center-distance or center-near MFCLs, respectively. Because of zone geometry in the concentric MFCLs tested, the highly aberrated transition zone between the distance and near optics contributed a significant proportion and
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
Espy, J W
In a review of the literature, it became apparent that there were very few articles describing the advantages, as well as the fitting techniques, of lathe-cut hydrophilic contact lenses. Few practitioners, including those who fit other types of hydrophilic lenses and hard lenses, have had any experience with this lens, and considerable interest has been generated by fragmentary reports of good results. This paper describes in detail the geometry of the first lathe-cut hydrophilic lens approved by the Federal Drug Administration, the fitting methods utilizing trial lenses, and the results of 100 patients successfully fitted.
Danion, Anne; Arsenault, Isabelle; Vermette, Patrick
In vitro methods to evaluate antibacterial activity were used with contact lenses bearing levofloxacin-loaded liposomes developed for the prevention and treatment of bacterial ocular infections such as keratitis. Levofloxacin was incorporated into liposomes before these intact liposomes were immobilized onto the surfaces of soft contact lenses using a multilayer immobilization strategy. The release of levofloxacin from contact lenses bearing 2, 5, and 10 layers of liposomes into a saline buffer at 37 degrees C was monitored by fluorescence. The levofloxacin release, as a function of time, was described by a mechanism taking into account two independent first-order kinetic models. The total release of levofloxacin from the contact lenses was completed within 6 days. The release of levofloxacin from contact lenses bearing 10 layers of liposomes and subsequently soaked overnight in a levofloxacin solution was also studied and compare to that of dried contact lenses without any chemical modification rehydrated in a levofloxacin solution. The antibacterial activity of the liposome-coated contact lenses against Staphylococcus aureus was evaluated by measuring (i) the diameters of the inhibition zone on an agar plate and (ii) the optical density using a broth assay. The liposome-coated lenses showed an antibacterial activity both on agar and in broth following 24 h. When initial bacteria inocula were equal or below 10(6) CFU/mL, all the bacteria were inhibited within 2 h. When using initial bacteria inocula of 10(8) CFU/mL, an initial burst release provided by soaking the liposomal lenses was required for the first hours to inhibit bacteria growth. (c) 2007 Wiley-Liss, Inc. and the American Pharmacists Association.
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.
Keith, D; Hong, B; Christensen, M
A quick, simple, and efficient extraction technique was developed for the removal of protein from soft hydrophilic contact lenses. An extraction solvent consisting of a 50:50 mix of 0.2% trifluoroacetic acid and acetonitrile was used to remove protein from in vitro laboratory-deposited and human-worn contact lenses. The protein removed was analyzed using HPLC, bicinchoninic acid (BCA) analysis, and SDS-PAGE gel electreophoresis. Extraction efficiency for lysozyme from laboratory-deposited Group IV lenses was determined to be approximately 100%. Group IV human-worn contact lenses were extracted and analyzed for lysozyme by HPLC and total protein by bicinchoninic acid (BCA) analysis. Groups I, II, III, and IV contact lenses deposited with an artificial tear protein solution and human-worn lenses were extracted and analyzed by SDS-PAGE gel electreophoresis and micro-BCA. The ACN/TFA procedure offers a simple, quick, and efficient extraction technique for removal of protein from contact lenses for subsequent analysis.
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
... Assisted In Situ Keratomileusis; Laser vision correction; Nearsightedness - Lasik; Myopia - Lasik ... cornea (curvature) and the length of the eye. LASIK uses an excimer laser (an ultraviolet laser) to ...
Yuksel, Erdem; Yalcin, Nuriye Gokçen; Kilic, Gaye; Cubuk, Mehmet Ozgur; Ozmen, Mehmet Cuneyt; Altay, Aylin; Çağlar, Kayhan; Bilgihan, Kamil
To investigate the agents of bacterial contamination of contact lenses after corneal collagen cross-linking (CCL), and to present the possible changes of ocular flora after riboflavin/ultraviolet A. Seventy-two contact lenses of patients who underwent CCL and 41 contact lenses of patients who underwent photorefractive keratectomy (PRK) as control group were enrolled to the study. After 48 h of incubation, broth culture media was transferred to plates. Samples were accepted as positive if one or more colony-forming units were shown. There were positive cultures in 12 (16.7%) contact lenses in the CCL group and 5 (12.2%) had positive cultures in PRK group. Coagulase-negative staphlycocci (CNS) were the most frequent microorganism. Alpha hemolytic streptococci and Diphteroid spp. were the other isolated microorganisms. Bacterial colonization can occur during and early after the CCL procedure in epithelial healing. To prevent corneal infections after the treatment, prophylactic antibiotics should be prescribed.
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.
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.
Papadatou, Eleni; Del Águila-Carrasco, Antonio J; Esteve-Taboada, José J; Madrid-Costa, David; Cerviño-Expósito, Alejandro
To analytically assess the effect of pupil size upon the refractive power distributions of different designs of multifocal contact lenses. Two multifocal contact lenses of center-near design and one multifocal contact lens of center-distance design were used in this study. Their power profiles were measured using the NIMO TR1504 device (LAMBDA-X, Belgium). Based on their power profiles, the power distribution was assessed as a function of pupil size. For the high addition lenses, the resulting refractive power as a function of viewing distance (far, intermediate, and near) and pupil size was also analyzed. The power distribution of the lenses was affected by pupil size differently. One of the lenses showed a significant spread in refractive power distribution, from about -3 D to 0 D. Generally, the power distribution of the lenses expanded as the pupil diameter became greater. The surface of the lens dedicated for each distance varied substantially with the design of the lens. In an experimental basis, our results show how the lenses power distribution is affected by the pupil size and underlined the necessity of careful evaluation of the patient's visual needs and the optical properties of a multifocal contact lens for achieving the optimal visual outcome.
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.
Vishnubhatla, Sravya; Borchman, Douglas; Foulks, Gary N
Accelerated evaporation of tears may contribute to dry eye symptoms. It is not clear whether contact lenses decrease or increase the rate of evaporation of tears. In this study, the rates of evaporation through contact lenses (ERTCL) were measured in vitro to gain insight to this question. Contact lenses were equilibrated with various solutions to determine if they influenced ERTCL in vitro. ERTCL was measured gravimetrically. ERTCL measured in vitro for used contact lenses was about 20% faster than for buffer alone suggesting that natural tear components bound to the lenses changed the ERTCL. One natural tear component that binds to contact lenses is waxes. Equilibration of contact lenses with wax increased the ERTCL by about 30% suggesting that waxes might potentially increase ERTCL in vivo. Squalene, found in sebum and possibly meibum was infused into the contact lenses as a step toward decreasing the ERTCL. Squalene decreased ERTCL by over 60% in vitro. Soaking a contact lens in DuraSite(®) with benzalkonium chloride (BAK) did not alter the ERTCL. ERTCL were about 40% higher than the evaporation rate of DuraSite(®) alone or without BAK. In addition to lowering the ERTCL, the squalene in contact lenses could be a source of terpenoids to replace the terpenoids deficient in patients with MGD. If the ERTCL could be minimized in vivo, contact lenses could potentially be used to relieve dry eye symptoms in patients with evaporative dry eye. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Vermeltfoort, Pit B J; van der Mei, Henny C; Busscher, Henk J; Hooymans, Johanna M M; Bruinsma, Gerda M
The aim of this study was to determine the transfer of Pseudomonas aeruginosa No. 3 and Staphylococcus aureus 835 from contact lenses to surfaces with different hydrophobicity and roughness. Bacteria were allowed to adhere to contact lenses (Surevue, PureVision, or Focus Night & Day) by incubating the lenses in a bacterial suspension for 30 min. The contaminated lenses were put on a glass, poly(methylmethacrylate), or silicone rubber substratum, shaped to mimic the eye. After 2 and 16 h, lenses were separated from the substrata and bacteria were swabbed off from the respective surfaces and resuspended in saline. Appropriate serial dilutions of these suspensions were made, from which aliquots were plated on agar for enumeration. Bacterial transfer varied between 4 and 60%, depending on the combination of strain, contact time, contact lens, and substratum surface. For P. aeruginosa No. 3, transfer was significantly higher after 16 h than after 2 h, whereas less increase with time was seen for S. aureus 835. Bacterial transfer from all tested contact lenses was least to silicone rubber, the most hydrophobic and roughest substratum surface included. (c) 2004 Wiley Periodicals, Inc.
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.
Schornack, Muriel; Rice, Melissa; Hodge, David
To assess the accuracy of Tonopen XL measurement of intraocular pressure (IOP) through low-power (-0.25 to -3.00) and high power (-3.25 to -6.00) silicone hydrogel lenses of 3 different materials (galyfilcon A, senofilcon A, and lotrafilcon B). Seventy-eight patients were recruited for participation in this study. All were habitual wearers of silicone hydrogel contact lenses, and none had been diagnosed with glaucoma, ocular hypertension, or anterior surface disease. IOP was measured with and without lenses in place in the right eye only. Patients were randomized to initial measurement either with or without the lens in place. A single examiner collected all data. No statistically significant differences were noted between IOP measured without lenses and IOP measured through low-power lotrafilcon B lenses or high-power or low-power galyfilcon A and senofilcon A lenses. However, we did find a statistically significant difference between IOP measured without lenses and IOP measured through high-power lotrafilcon B lenses. In general, Tonopen XL measurement of IOP through silicone hydrogel lenses may be sufficiently accurate for clinical purposes. However, Tonopen XL may overestimate IOP if performed through a silicone hydrogel lens of relatively high modulus.
Garcia-Romo, Esperanza; Perez-Rico, Consuelo; Roldán-Díaz, Isabel; Arévalo-Serrano, Juan; Blanco, Román
To investigate the feasibility, effectiveness and acceptability of using prosthetic occluding contact lenses (OCLs) to treat moderate amblyopia in adults and of the role of the multifocal visual evoked potential (mfVEP) as a predictor of postamblyopic therapy. A comparative, prospective, interventional, case series pilot study with amblyopic adults (mean age: 40 years, range 20-50 years) allocated into two intervention groups: eye patching and OCL. The primary outcome variable was logarithm of the minimum angle of resolution (logMAR) best-corrected visual acuity (BCVA), and secondary outcomes were mfVEP amplitude and latency and patients' health-related quality of life National Eye Institute Visual Function Questionnaire (NEI VFQ-25). Significant improvements in pre- to postamblyopic therapy BCVA were seen at 1.5 months in the OCL group [0.29 logMAR, 95% confidence interval (CI): 0.10-0.47 versus 0.11 logMAR, 95% CI: 0.02-0.19; p < 0.001] and eye patching group (0.29 logMAR, 95% CI: 0.17-0.40 versus 0.18 logMAR, 95% CI: 0.12-0.23; p < 0.01). Post-treatment BCVA was inversely related to age (R: 0.009, 95% CI: -0.02 to -0.001; p = 0.04) and the presence of strabismus (R: -0.3, 95% CI: -0.434 to -0.17; p = 0.001). No significant changes in the number and size of the abnormal mfVEP amplitude and latency defects were observed after occlusion. The NEI VFQ-25 composite score showed significant improvement in the OCL users at 12 months compared to eye patching. Significant vision improvement can be achieved, making occlusion with OCLs an effective and more acceptable therapy for adults with amblyopia. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.
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
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
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.
Das, T; Sharma, S; Singh, J; Rao, V; Chalam, K V
Wide-field vitrectomy contact lenses are currently sterilized with ethylene oxide gas, and other lenses with autoclaving. To maintain a large inventory or possibly run the risk of loss of lens quality with repeated autoclaving, glutaraldehyde 2% and povidone iodine 5% solution were evaluated as possible sterilizing agents. Ethylene oxide presterilized lenses were contaminated with known concentrations (10(5) organisms/mL) of bacteria (S. epidemidis, P. aeruginosa, B. subtilis), and fungi (A. flavus, C. albicans) for 5 minutes. The test lenses were treated with glutaraldehyde or povidone iodine for 5, 10, 30, 60, and 120 minutes, and controls with sterilized water for a similar duration. Following treatment, both test and control lenses were sampled with sterile cotton swabs. The swabs were cultured for bacteria (tryptone soya broth 48 hours), and fungi (Saubourd's dextrose broth 5 days). The culture was negative for both glutaraldehyde- and povidone iodine-treated lenses against all organisms at all time points except B subtilis, which needed 120 minutes treatment. Two hours contact time with glutaraldehyde 2% or providone iodine 5% can sterilize vitrectomy contact lenses against common bacteria and fungi without affecting lens quality.
Hondur, Ahmet; Bilgihan, Kamil; Cirak, Meltem Yalinay; Dogan, Ozgur; Erdinc, Alper; Hasanreisoglu, Berati
To evaluate the extent and agents of bacterial contamination of bandage disposable soft contact lenses after laser subepithelial keratectomy (LASEK) and to correlate the findings with clinical data. Disposable soft contact lenses were collected from 52 eyes of 26 consecutive patients treated with LASEK for myopia. The patients were treated with a fixed combination of tobramycin and diclofenac until epithelial closure. The lenses were removed on the fourth or fifth postoperative day with sterile forceps and immediately placed in sterile tubes containing culture media brain-heart infusion broth. The lenses were evaluated for microbial colonization. Of the 52 contact lenses analyzed, six (11.5%) had positive cultures. However, no clinical finding of infection was noted. Isolated microorganisms were coagulase-negative staphylococci (two lenses), Stenotrophomonas maltophilia (two lenses), Acinetobacter species (one lens), and Aeromonas hydrophila (one lens). Except for one case, the microorganisms were sensitive to the administered antibiotic. The risk of infectious keratitis after LASEK seems to be low. Except for staphylococci, the isolated microorganisms have not been previously reported to colonize the ocular surface or cause keratitis after refractive surgery. These findings may suggest a changing trend of potentially infectious agents after surface ablation.
Babaei Omali, Negar; Proschogo, Nicholas; Zhu, Hua; Zhao, Zhenjun; Diec, Jennie; Borazjani, Roya; Willcox, Mark D P
Protein and lipid deposits on contact lenses may contribute to clinical complications. This study examined the effect of phospholipids on the adhesion of bacteria to contact lenses. Worn balafilcon A (n = 11) and senofilcon A (n = 11) were collected after daily wear and phospholipids were extracted in chloroform:methanol. The amount of phospholipid was measured by electrospray ionization mass spectrometry. Unworn lenses soaked in phospholipids were exposed to Pseudomonas aeruginosa and Staphylococcus aureus. After 18 h incubation, the numbers of P. aeruginosa or S. aureus that adhered to the lenses were measured. Phospholipid was tested for possible effects on bacterial growth. A broad range of sphingomyelins (SM) and phosphatidylcholines (PC) were detected from both types of worn lenses. SM (16:0) (m/z 703) and PC (34:2) (m/z 758) were the major phospholipids detected in the lens extracts. Phospholipids did not alter the adhesion of any strain of P. aeruginosa or S. aureus (p > 0.05). Phospholipids (0.1 mg/mL) showed no effect on the growth of P. aeruginosa 6294 or S. aureus 031. Phospholipids adsorb/absorb to contact lenses during wear, however, the major types of phospholipids adsorbed to lenses do not alter bacterial adhesion or growth.
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 (C 8 ), Tween 20 (C 12 ), Tween 80 (C 18 )] 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.
Willcox, M D; Power, K N; Stapleton, F; Leitch, C; Harmis, N; Sweeney, D F
The aim of this paper was to determine the possible contamination sources of contact lenses during wear. Potential sources of the microbiota that colonized hydrogel contact lenses during wear were examined. The microorganisms that colonize contact lenses were grown, identified, and compared to those microorganisms that colonized the lower lid margins, upper bulbar conjunctiva, hands, and contact lens cases of contact lens wearers. In addition, the incidence of contamination of the domestic water supply in the Sydney area was obtained, and this was compared to the incidence of colonization of contact lenses by microorganisms in general and gram-negative bacteria in particular. There was a wide diversity of bacteria that were isolated from each site sampled. Coagulase-negative staphylococci and Propionibacterium spp. were the most common isolates from all ocular sites examined, and constituted the normal ocular microbiota. Other bacteria, including members of the families Enterobacteriaceae and Pseudomonadaceae, were isolated infrequently from all sites, but most frequently from contact lens cases. Statistical analysis revealed that there was a correlation between the isolation of bacteria from the contact lens and the lower lid margin (p < 0.001). Analysis of this correlation revealed that this was true for the normal microbiota. A correlation was also noted between the colonization of contact lenses by gram-negative bacteria and contamination of the domestic water supply. This study has demonstrated that the likely route for the normal ocular microbiota colonizing contact lenses is via the lid margins, whereas colonization by gram-negative bacteria, including potential agents of microbial keratitis, is likely to be from the domestic water supply.
Coagulase-negative staphylococci and diphtheroids are normal inhabitants of the outer surface of the human eye. These microorganisms serve as part of the defense mechanism of the ocular anatomy in preventing colonization and infection by pathogenic bacteria. Nevertheless, infections associated with contaminated solutions and cases became serious problems for people who wear soft contact lenses. The aim of this study is to isolate and identify aerobic bacteria, particularly, gram-negative species associated with the use of extended-wear soft contact lenses. Extended-wear contact lenses were collected, using aseptic technique, from the eyes of individuals after 30 days of extended wear (5-7 day intermittent periods) and were examined for adhered aerobic bacteria. Coagulase-negative staphylococci were isolated from 74% of the lenses. Serratia marcescens was found at an incidence of 10% and Pseudomonas aeruginosa at an incidence of 6%. The presence of species of bacteria, including P. aeruginosa and S. marcescens, which have been associated with daily wear soft contact lenses, solutions, and cases also seem to be associated with extended-wear lenses.
Problem ............... .......... 7 Subjects .. ............... ............... 9 *Material and Methods .. ............... ......... 14 Treatment of...abil- ity to achieve visual acuity comparable to that with their spectacle lenses, these patients frequently complain that their new vision is "not...available through Cadwell Laboratories) and the Arden Photographic Plates (available from American Optical Co.). In light of these new capabilities and
Cox, Stephanie M; Berntsen, David A; Bickle, Katherine M; Mathew, Jessica H; Powell, Daniel R; Little, B Kim; Lorenz, Kathrine Osborn; Nichols, Jason J
To assess whether patient-reported measures are improved with soft toric contact lenses (TCLs) compared with soft spherical contact lenses (SCLs) and whether clinical time needed to fit TCL is greater than SCL. Habitual contact lens wearers with vertexed spherical refraction +4.00 to +0.25 D or -0.50 to -9.00 D and cylinder -0.75 to -1.75 DC were randomly assigned to be binocularly fitted into a TCL or SCL, and masked to treatment assignment. Time to successful fit was recorded. After 5 days, the National Eye Institute Refractive Error Quality of Life Instrument (NEI-RQL-42) and modified Convergence Insufficiency Symptom Survey (CISS) were completed. After washout, subjects were fit into the alternative lens design (TCL or SCL). Outcomes were evaluated using linear mixed models for the time to fit and CISS score, generalized linear model for the successful fit, and Wilcoxon tests for the NEI-RQL-42. Sixty subjects (71.7% women, mean age [±SD] = 27.5±5.0 years) completed the study. The mean time to fit the TCL was 10.2±4.3 and 9.0±6.5 min for the SCL (least square [LS] mean difference (TCL-SCL)=1.2, P=0.22). Toric contact lens scored better than SCL in global NEI-RQL-42 score (P=0.006) and the clarity of vision (P=0.006) and satisfaction with correction subscales (P=0.006). CISS showed a 15% reduction in symptoms (LS mean difference [TCL-SCL]=-2.20, P=0.02). TCLs are a good option when trying to improve the vision of patients with low-to-moderate astigmatism given the subjective improvements in outcomes.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.
Gu, Xiaobo; Jennings, Jacob D; Snarr, Jason; Chaudhary, Vinod; Pollard, Jacob E; Savage, Paul B
We provided contact lens hydrogels with an antibacterial innate immune function using nonpeptide mimics of endogenous antimicrobial peptides. Antimicrobial peptide mimics, ceragenins, were prepared for either covalent attachment to hydrogels or for controlled elution from lenses. The lipophilicity of the ceragenins was varied incrementally to provide differing levels of association with hydrophobic domains in lenses. Ceragenin-containing lenses were challenged repeatedly with Staphylococcus aureus or Pseudomonas aeruginosa in nutrient media. Bacterial growth and biofilm formation on lenses were quantified. A ceragenin covalently fixed in lenses effectively inhibited S. aureus biofilm formation on lenses in 10% tryptic soy broth (approximately 3-log reduction), but did not reduce biofilm formation in 100% tryptic soy broth. Ceragenins designed to elute from lenses were incorporated at 1% relative to the dry weight of the lenses. The ceragenin with the optimal lipid content, CSA-138, prevented bacterial colonization of lenses for 15 days with P. aeruginosa and for 30 days with S. aureus (daily exchange of growth media and reinoculation with 10⁶ CFU). Measurement of CSA-138 elution showed that concentrations of the ceragenin never exceeded 5 μg/mL in a 24-hour period and that after 4 days of elution, concentrations dropped to <0.5 μg/mL, while maintaining antibacterial activity. Ceragenin CSA-138 appears well suited for providing an innate immune-like function to abiotic hydrogel contact lenses for extended periods of time. Elution of even low concentrations of CSA-138 (<0.5 μg) is sufficient to eliminate inocula of 10⁶ CFU of S. aureus and P. aeruginosa.
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.
Tuli, Sonal S; Iyer, Sandhya A; Driebe, William T
To review studies of fungal keratitis related to contact lenses and determine whether the recent insurgence is a new phenomenon or an exacerbation of an ongoing trend. A review of the recent literature on contact lens-related fungal ulcers and a comparison to older studies. The incidence of fungal keratitis associated with contact lenses increased from 5% in the 1980s to between 10% and 25% in the 1990s and was noted to be 44% in Florida at the turn of the century. The most recent study from Florida showed that the incidence had increased from 29% in the late 1990s to 52% in the early 2000s, even before the Fusarium keratitis epidemic in 2004 and 2005. This increase mainly represented an increase in the number related to nontherapeutic contact lenses. Contact lens-related fungal keratitis was relatively rare 20 years ago. However, the incidence has progressively increased since then. Contact lens-related fungal ulcers had become more common even before the recent Fusarium keratitis epidemic. This change may be related to changing contact lens care habits and younger patients being fitted with contact lenses.
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.
Omaña-Molina, Maritza A; González-Robles, Arturo; Salazar-Villatoro, Lizbeth; Bernal-Escobar, Alexander; Durán-Díaz, Angel; Méndez-Cruz, Adolfo René; Martínez-Palomo, Adolfo
To describe the adhesion properties of Acanthamoeba castellanii trophozoites to silicone hydrogel contact lenses of first generation (lotrafilcon A), second generation (galyfilcon A), and third generation (comfilcon A) and correlate the results with their specific surface characteristics, time of interaction, and suspension media. Qualitative and quantitative assessments of the adhesion of 200 trophozoites of A. castellanii on contact lenses in culture medium (Bacto Casitone) and isotonic saline (IS) at different time points (15 minutes and 6 hours) were determined. By scanning electron microscopy, A. castellanii trophozoites were observed firmly adhered to the surface of hydrogel lenses after 15 minutes of interaction. The surface of lotrafilcon A lenses on which amoebae adhere better (16.4±10.2 amoebae/lens section) is rough and folded, which increases the contact surface with trophozoites, allowing acanthopodia to attach firmly. Contrarily, galyfilcon A lenses have a smoother surface, and lower numbers of amoebae were observed adhered to these lenses (4.7±2.9 amoebae/lens section). Even fewer amoebae adhered to the smoother surface of the comfilcon A lens (2.2±1.7 amoebae/lens section). Trophozoites showed similar behavior in both Bacto Casitone medium and IS. A rough surface may contribute to better adhesion of amoebae to silicone hydrogel lenses. Although a reduced numbers of trophozoites adhered to smooth lenses, trophozoites are a risk factor for amoebic keratitis. Isotonic saline facilitated trophozoite survival, suggesting that homemade saline solutions may contribute to the persistence of trophozoites, especially when there is no proper hygiene regimen used with the contact lens cases.
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.
Vidotti, Vanessa Gonçalves; Kamegasawa, Amélia
To analyze the ametropy, way of acquisition, the care and complications related to contact lens wear among medical students from Faculdade de Medicina de Botucatu da Universidade Estadual Paulista-UNESP--Botucatu (SP). Questionnaire applied to students from the 1st to the 6th year of the Medical school of the Faculdade de Medicina de Botucatu da Universidade Estadual Paulista-UNESP--Botucatu (SP), forming an analytical cross-sectional survey. 27.4% of the students use contact lenses, and among them 94.8% use soft contact lenses and 98% have negative degree. 46.9% discard their contact lens monthly. 63.9% have an average daily use of 14 hours, 14.1% acquire the contact lenses from optician stores or at pharmacies and 46.5% of the students clean their contact lenses when they put them on and take them off. Regarding complications, 51.0% reported ocular redness; 44.5%, blurred vision; and 42.6%, foreign body sensation, whereas only 4 students reported "keratitis". We concluded that the inadequate adaptation that occurs even in users knowledgeable about this issue such as medical students, has increased the risk of complications. This fact indicates that more attention must be paid to contact lens care in order to prevent permanent visual deficit.
García-Lázaro, Santiago; Ferrer-Blasco, Teresa; Madrid-Costa, David; Albarrán-Diego, César; Montés-Micó, Robert
To assess and compare the effects of four simultaneous-image multifocal contact lenses (SIMCLs), and those with distant-vision-only contact lenses on visual performance in early presbyopes, under dim conditions, including the effects of induced glare. In this double-masked crossover study design, 28 presbyopic subjects aged 40 to 46 years were included. All participants were fitted with the four different SIMCLs (Air Optix Aqua Multifocal [AOAM; Alcon], PureVision Multifocal [PM; Bausch & Lomb], Acuvue Oasys for Presbyopia [AOP; Johnson & Johnson Vision], and Biofinity Multifocal [BM; CooperVision]) and with monofocal contact lenses (Air Optix Aqua, Alcon). After 1 month of daily contact lens wearing, each subject's binocular distance visual acuity (BDVA) and binocular distance contrast sensitivity (BDCS) were measured using the Functional Visual Analyzer (Stereo Optical Co., Inc.) under mesopic conditions (3 candela [cd]/m) both with no glare and under the 2 levels of induced glare: 1.0 lux (glare 1) and 28 lux (glare 2). Among the SIMCLs, in terms of BDVA, AOAM and PM outperformed BM and AOP. All contact lenses performed better at level without glare, followed by Glare 1, and with the worst results obtained under glare 2. Binocular distance contrast sensitivity revealed statistically significant differences for 12 cycles per degree (cpd). Among the SIMCLs, post hoc multiple comparison testing revealed that AOAM and PM provided the best BDCS at the three luminance levels. In both cases, BDVA and BDCS at 12 cpd, monofocal contact lenses outperformed all SIMCL ones at all lighting conditions. Air Optix Aqua Multifocal and PM provided better visual performance than BM and AOP for distance vision with low addition and under dim conditions, but they all provide worse performance than monofocal contact lenses.
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.
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.
Omali, Negar Babaei; Zhu, Hua; Zhao, Zhenjun; Willcox, Mark D P
Bacterial adhesion to contact lenses is believed to be the initial step for the development of several adverse reactions that occur during lens wear such as microbial keratitis. This study examined the effect of combinations of proteins on the adhesion of bacteria to contact lenses. Unworn balafilcon A and senofilcon A lenses were soaked in commercially available pure protein mixtures to achieve the same amount of various proteins as found ex vivo. These lenses were then exposed to Pseudomonas aeruginosa and Staphylococcus aureus. Following incubation, the numbers of P. aeruginosa or S. aureus that adhered to the lenses were measured. The possible effect of proteins on bacterial growth was investigated by incubating bacteria in medium containing protein. Although there was a significant (p < 0.003) increase in the total or viable counts of one strain of S. aureus (031) on balafilcon A lenses soaked in the lysozyme/lactoferrin combination, the protein adhered to lenses did not alter the adhesion of any other strains of P. aeruginosa or S. aureus (p > 0.05). Growth of S. aureus 031 (p < 0.0001) but not of P. aeruginosa 6294 was stimulated by addition of lysozyme/lactoferrin combination (2.8/0.5 mg/mL). Addition of lipocalin did not affect the growth of any strains tested (p > 0.05). Adsorption of amounts of lysozyme and lactoferrin or lipocalin equivalent to those extracted from worn contact lenses did not affect the adhesion of most strains of S. aureus or P. aeruginosa to lens surfaces.
Iskeleli, Güzin; Bahar, Hrisi; Eroglu, Ebru; Torun, Muzeyyen Mamal; Ozkan, Sehirbay
To determine the effect of 30-day continuous-wear silicone hydrogel contact lenses on the conjunctival flora in asymptomatic wearers. The authors studied 29 eyes of 15 patients wearing Focus NIGHT & DAY silicone hydrogel contact lenses for up to 30 nights of continuous wear. The average age of the patients was 25.54 +/- 8.98 years. Cultures of the inferior cul-de-sac were taken bilaterally from all eyes, before and after lens wear in asymptomatic patients. The isolation and identification of bacteria were made by standard clinical laboratory methods. The number of eyes whose conjunctival cultures were sterile before using the lenses significantly decreased (P = 0.0005), and the number of eyes with a growth of coagulase-negative staphylococci and diphtheroid rods in their conjunctival cultures significantly increased after using these lenses (P = 0.001 and P = 0.031, respectively). Conversely, a statistically significant difference was not found in the number of eyes that carried Propionibacterium acnes and Fusobacterium nucleatum in their conjunctival cultures before and after using the 30-day continuous-wear silicone hydrogel lenses (P = 0.998 and P = 0.488, respectively). The results suggest that the sterility of the conjunctiva significantly decreased after using 30-day continuous-wear silicone hydrogel contact lenses. In addition, the number of bacteria of the normal conjunctival flora significantly increased after the use of these lenses. Contamination by the bacteria of the eyelids may be a possible colonization factor in this study group. Therefore, it is appropriate to examine the patients who wear these lenses more frequently.
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
Erickson, Graham B; Horn, Fraser C; Barney, Tyler; Pexton, Brett; Baird, Richard Y
The use of tinted and clear contact lenses (CLs) in all aspects of life is becoming a more popular occurrence, particularly in athletic activities. This study broadens previous research regarding performance-tinted CLs and their effects on measures of visual performance. Thirty-three subjects (14 male, 19 female) were fitted with clear B&L Optima 38, 50% visible light transmission Amber and 36% visible light transmission Gray-Green Nike Maxsight CLs in an individualized randomized sequence. Subjects were dark-adapted with welding goggles before testing and in between subtests involving a Bailey-Lovie chart and the Haynes Distance Rock test. The sequence of testing was repeated for each lens modality. The Amber and Gray-Green lenses enabled subjects to recover vision faster in bright sunlight compared with clear lenses. Also, subjects were able to achieve better visual recognition in bright sunlight when compared with clear lenses. Additionally, the lenses allowed the subjects to alternate fixation between a bright and shaded target at a more rapid rate in bright sunlight as compared with clear lenses. Subjects preferred both the Amber and Gray-Green lenses over clear lenses in the bright and shadowed target conditions. The results of the current study show that Maxsight Amber and Gray-Green lenses provide better contrast discrimination in bright sunlight, better contrast discrimination when alternating between bright and shaded target conditions, better speed of visual recovery in bright sunlight, and better overall visual performance in bright and shaded target conditions compared with clear lenses.
Singh, Shwetambari; Satani, Dipali; Patel, Amit; Vhankade, Ravinder
To identify the microbiological profile and evaluate the clinical course and outcomes in patients who developed severe infectious keratitis after colored cosmetic contact lens wear. This case series includes 13 patients who developed severe infectious keratitis after colored cosmetic contact lens wear. A detailed history regarding contact lens availability and storage and handling techniques was taken. All patients underwent standard diagnostic microbiological evaluation followed by culture-guided topical antimicrobial therapy. Of 13 patients, 8 were male and 5 were female, with mean age at presentation of 19 ± 3.8 years. All patients were emmetropic, and lenses were worn solely for cosmetic purposes. Seven lenses were dispensed without prescription or fitting from an unlicensed optical shop, 5 patients had shared lenses with friends/relatives, and 1 patient obtained the lens from the garbage. None of the patients followed the recommended contact lens handling and storage techniques. The causative microorganisms included Pseudomonas aeruginosa (54%), Staphylococcus aureus (25%), and Staphylococcus epidermidis (17%), with 1 case of viral keratitis. In 62% of cases, ulcer size was ≥5 × 5 mm and posttreatment corrected visual acuity was 6/24 or less. All patients responded well to topical antimicrobials, and none required surgical intervention. Over-the-counter use of decorative lenses as a cosmetic aid is rapidly increasing. Easy and unmonitored availability of these cosmetic lenses is followed by severe sight-threatening complications in young emmetropic individuals.
Yan, G; Nyquist, G; Caldwell, K D; Payor, R; McCraw, E C
This study was done to characterize and quantify the protein deposits on worn contact lenses and to measure the residual deposits after extraction in 2% sodium dodecyl sulfate and the total protein deposits on worn vifilcon, atlafilcon, and tefilcon lenses (Food and Drug Administration Types IV, II, and I, respectively). Contact lens extracts were separated with gel electrophoresis, and the amount of protein was estimated after silver staining and densitometry. To determine the residual deposits, the contact lenses were hydrolyzed, and amino acid analysis was carried out by reverse-phase high-performance liquid chromatography after precolumn derivatization with phenylisothiocyanate. Refinement of the hydrolysis conditions was undertaken to minimize interference by the lens polymers. The extraction removed only approximately 25% of the protein deposits. Mild hydrolytic conditions, 20 hr in 6 N HCl at 105 degrees C, were found to cause minimal polymer interference. Of the 350, 10, and 20 micrograms of protein typically determined on whole vifilcon, atlafilcon, and tefilcon lenses, the polymers were estimated to account for 4, 0.5, and less than 0.4 micrograms, respectively. Hydrolysis of worn contact lenses with subsequent amino acid separation can be applied to determine the total protein deposits without the uncertainty inherent in extraction of the deposits.
Hui, Alex; Willcox, Mark; Jones, Lyndon
The purpose of this study was to evaluate ciprofloxacin-releasing silicone hydrogel contact lens materials in vitro and in vivo for the treatment of microbial keratitis. Model silicone hydrogel contact lens materials were manufactured using a molecular imprinting technique to modify ciprofloxacin release kinetics. Various contact lens properties, including light transmission and surface wettability, were determined, and the in vitro ciprofloxacin release kinetics elucidated using fluorescence spectrophotometry. The materials then were evaluated for their ability to inhibit Pseudomonas aeruginosa growth in vitro and in an in vivo rabbit model of microbial keratitis. Synthesized lenses had similar material properties to commercial contact lens materials. There was a decrease in light transmission in the shorter wavelengths due to incorporation of the antibiotic, but over 80% light transmission between 400 and 700 nm. Modified materials released for more than 8 hours, significantly longer than unmodified controls (P < 0.05). In vivo, there was no statistically significant difference between the number of colony-forming units (CFU) recovered from corneas treated with eye drops and those treated with one of two modified contact lenses (P > 0.05), which is significantly less than corneas treated with unmodified control lenses or those that received no treatment at all (P < 0.05). These novel contact lenses designed for the extended release of ciprofloxacin may be beneficial to supplement or augment future treatments of sight-threatening microbial keratitis. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.
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.
Henriques, Mariana; Sousa, Cláudia; Lira, Madalena; Elisabete, M; Oliveira, Real; Oliveira, Rosário; Azeredo, Joana
The purpose of this study is to compare the adhesion capabilities of the most important etiologic agents of microbial ocular infection to the recently available silicone-hydrogel lenses with those to a conventional hydrogel lens. In vitro static adhesion assays of Pseudomonas aeruginosa 10,145, Staphylococcus epidermidis 9142 (biofilm-positive), and 12,228 (biofilm-negative) to two extended-wear silicone-hydrogel lenses (balafilcon A and lotrafilcon A), a daily wear silicone-hydrogel lens (galyfilcon A) and a conventional hydrogel (etafilcon A) were performed. To interpret the adhesion results, lens surface relative hydrophobicity was assessed by water contact angle measurements. P. aeruginosa and S. epidermidis 9142 exhibited greater adhesion capabilities to the extended wear silicone-hydrogel lenses than to the daily wear silicone- and conventional hydrogel lenses (p < 0.05). No statistical differences were found between the adhesion extent of these strains to galyfilcon A and etafilcon A. The biofilm negative strain of S. epidermidis adhered in larger extents to the silicone-hydrogel lenses than to the conventional hydrogel (p < 0.05), but in much lower amounts than the biofilm-positive strain. The water contact angle measurements revealed that the extended wear silicone-hydrogel lenses are hydrophobic, whereas the daily wear silicone- and conventional hydrogel lenses are hydrophilic. As a result of their hydrophobicity, the extended wear silicone-hydrogel lenses (lotrafilcon A and balafilcon A) may carry higher risk of microbial contamination than both the hydrophilic daily wear silicone-hydrogel lens, galyfilcon A and the conventional hydrogel lens, etafilcon A.
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.
Gabriel, Manal M; McAnally, Cindy; Bartell, John
The aim of this study was to use antimicrobial efficacy endpoint methodology to determine compatibility of multipurpose disinfecting solutions (MPSs), lens cases, and hydrogel lenses for disinfection (AEEMC) against International Organization for Standardization (ISO)-specified microorganisms and clinical ocular isolates of Stenotrophomonas maltophilia. Six MPSs (PQ/Aldox 1, 2, and 3; PQ/Alexidine; PQ/PHMB; and PHMB) were challenged against ISO-specified microorganisms and S. maltophilia using the AEEMC test. AEEMC tests were performed with and without balafilcon A, etafilcon A, and senofilcon A lenses in lens cases with organic soil. Exposure times included disinfection time (DT) and 24 hr. Additionally, all six MPSs were challenged with two strains of S. maltophilia, based on the ISO Stand-alone test. The efficacy against bacteria for PQ/Aldox and PQ/Alexidine MPSs was not diminished by the presence of lenses. The efficacy of PQ/PHMB and PHMB MPSs against Serratia marcescens was significantly reduced compared with the no-lens control at DT for at least one lens type. The PHMB MPS with lenses present also demonstrated reduced efficacy against Staphylococcus aureus at DT versus the control. PQ/Aldox MPSs retained activity against Fusarium solani with lenses present; however, all other test MPSs demonstrated reduced F. solani efficacy at DT with lenses present. With lenses, all MPSs showed reduced efficacy against Candida albicans. AEEMC antimicrobial efficacy test results vary based on challenge microorganism, contact lenses, and MPS biocide systems. This study highlights the importance of evaluating MPSs for compatibility with lenses and lens cases.
McAnally, Cindy; Bartell, John
Objective: The aim of this study was to use antimicrobial efficacy endpoint methodology to determine compatibility of multipurpose disinfecting solutions (MPSs), lens cases, and hydrogel lenses for disinfection (AEEMC) against International Organization for Standardization (ISO)–specified microorganisms and clinical ocular isolates of Stenotrophomonas maltophilia. Methods: Six MPSs (PQ/Aldox 1, 2, and 3; PQ/Alexidine; PQ/PHMB; and PHMB) were challenged against ISO-specified microorganisms and S. maltophilia using the AEEMC test. AEEMC tests were performed with and without balafilcon A, etafilcon A, and senofilcon A lenses in lens cases with organic soil. Exposure times included disinfection time (DT) and 24 hr. Additionally, all six MPSs were challenged with two strains of S. maltophilia, based on the ISO Stand-alone test. Results: The efficacy against bacteria for PQ/Aldox and PQ/Alexidine MPSs was not diminished by the presence of lenses. The efficacy of PQ/PHMB and PHMB MPSs against Serratia marcescens was significantly reduced compared with the no-lens control at DT for at least one lens type. The PHMB MPS with lenses present also demonstrated reduced efficacy against Staphylococcus aureus at DT versus the control. PQ/Aldox MPSs retained activity against Fusarium solani with lenses present; however, all other test MPSs demonstrated reduced F. solani efficacy at DT with lenses present. With lenses, all MPSs showed reduced efficacy against Candida albicans. Conclusions: AEEMC antimicrobial efficacy test results vary based on challenge microorganism, contact lenses, and MPS biocide systems. This study highlights the importance of evaluating MPSs for compatibility with lenses and lens cases. PMID:27598555
Lohmann, C P; Fitzke, F W; O'Brart, D; Muir, M K; Marshall, J
After photorefractive keratectomy (PRK) using excimer lasers (193 nm) many patients report the presence of halos around light sources at night. However, halos are not unique to PRK patients, as they are a common observation in myopic contact lens wearers. We present an objective measurement of the halos using a computerized technique. The patient fixated on a red cross within a white circle in the center of a video monitor which served as the halo source. The screen surrounding the circle was not illuminated. The operator controlled the movement of the white spot and moved the spot toward the halo source until the subject indicated when the cursor was at the outer parameter of the halo. Measurements were made at 30 degree intervals around the halo source and expressed as square degrees. The study found that spectacles, soft contact lenses, and excimer laser surgery were superior to hard contact lenses in terms of the size of the halo. A mean value of 2.51 square degrees was obtained for spectacles wearers compared with 3.18 square degrees for soft contact lenses, 3.14 square degrees for excimer laser patients with 4-millimeter ablation zone, 2.76 square degrees for excimer laser patients with a 5-millimeter ablation zone, and 89.5 square degrees for hard contact lenses. It appears that this device is very useful for measuring the halo size after excimer laser PRK. We concluded that halos were not a problem for our patients after excimer laser photorefractive keratectomy.
Dutta, Debarun; Cole, Nerida; Kumar, Naresh; Willcox, Mark D P
To develop a stable antimicrobial contact lens, which is effective against the International Organization for Standardization (ISO) panel microorganisms, Acanthamoeba castellanii and drug resistant strains of Pseudomonas aeruginosa and Staphylococcus aureus. Melimine was covalently incorporated into etafilcon A lenses. The amount of peptide present on the lens surface was quantified using amino acid analysis. After coating, the heat stability (121°C), lens surface hydrophobicity (by captive bubble), and in vitro cytotoxicity to mouse L929 cells of the lenses were investigated. Antimicrobial activity against the micro-organisms was evaluated by viable plate count and fluorescence microscopy, measuring the proportion of cell death compared with control lenses with no melimine. The most effective concentration was determined to be 152 ± 44 μg lens(-1) melimine on the lens surface. After coating, lenses were relatively hydrophilic and were nontoxic to mammalian cells. The activity remained high after autoclaving (e.g., 3.1, 3.9, 1.2, and 1.0 log inhibition against P. aeruginosa, S. aureus, A. castellanii, and Fusarium solani, respectively). Fluorescence microscopy confirmed significantly reduced (P < 0.001) adhesion of viable bacteria to melimine contact lenses. Viable count confirmed that lenses were active against all the bacteria and fungi from the ISO panel, Acanthamoeba and gave at least 2 log inhibition against all the multidrug resistant S. aureus and P. aeruginosa strains. Melimine may offer excellent potential for development as a broad spectrum antimicrobial coating for contact lenses, showing activity against all the bacterial and fungal ISO panel microorganisms, Acanthamoeba, and antibiotic resistant strains of P. aeruginosa and S. aureus.
Maïssa, Cécile; Guillon, Michel; Garofalo, Renee J
The principal objective of the study was to measure the conjunctival staining produced in the circumlimbal region by silicone hydrogel contact lenses with different edge designs. The secondary objective was to investigate the association between circumlimbal staining and comfort. Four silicone hydrogel contact lenses: ACUVUE OASYS (knife edge design), AIR OPTIX, Biofinity (chisel edge rounded edge combination), and PureVision (rounded edge design), and 1 hydrogel contact lens, ACUVUE 2 (knife edge design), were tested. The study was conducted on a cohort population of 27 established soft contact lens wearers, who wore each contact lens type, in a random order, for a period of 10 (±2) days. Circumlimbal staining was measured in a double-masked fashion through image analysis of digital photographs of lissamine green taken under controlled experimental conditions. The results obtained showed that contact lens edge design was the primary factor controlling circumlimbal staining for silicone hydrogel lenses: a rounded edge away from the ocular surface produced the lowest staining (average, 0.19%) and a knife edge in close apposition to the ocular surface produced the highest staining (average, 1.34%). Contact lens material rigidity was also identified to affect circumlimbal staining and an inverse association between circumlimbal staining and contact lens comfort was demonstrated: the rounded edge design produced the lowest comfort (72 of 100) and the knife edge design produced the highest (87 out of 100). Soft contact lens wear induces circumlimbal staining, the level of staining being influenced by the contact lens edge design. However, high level of circumlimbal staining is not associated with decreased comfort.
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.
Lievens, Christopher W; Connor, Charles G; Murphy, Heather
The current study evaluates the response of the ocular surface to extended contact lens wear by comparing a new silicone hydrogel lens to an ACUVUE 2 lens. Twenty subjects with an average age of 28 years were randomly assigned to a fitting with ACUVUE 2 or PureVision lenses. Ocular surface assessment by impression cytology was performed at baseline and for the 6 months after initiation of lens wear. Although goblet cell density significantly increased with wear time, no statistically significant difference was observed between the contact lens groups. The average baseline goblet cell percentages were as follows: ACUVUE 2 group, 1.44; PureVision group, 1.11. The 6-month averages were as follows: ACUVUE 2 group, 3.16; PureVision group, 2.22. It appears that silicone hydrogel lenses may be slightly less irritating to the ocular surface than lenses not containing silicone. This could be a promising indicator for successful 30-day continuous wear.
Schornack, Muriel M; Faia, Lisa J; Griepentrog, Gregory J
To report two cases of pseudomonas keratitis associated with daily wear of silicone hydrogel contact lenses. Medical records of two patients who developed pseudomonas keratitis while wearing silicone hydrogel lenses on a daily-wear schedule are reviewed and discussed. A 13-year-old girl who wore ACUVUE Advance lenses (Johnson & Johnson Vision Care, Jacksonville, FL) 12 to 14 hours daily developed a paracentral corneal ulcer in her left eye 4 months after beginning contact lens use. Cultures were positive for Pseudomonas aeruginosa. The ulcer responded to fortified antibiotics and resolved in 10 days. Best-corrected visual acuity after resolution of the ulcer was 20/25. A 58-year-old woman with a 30-year history of rigid gas-permeable contact lens wear was refitted with O2 Optix lenses (CIBA Vision, Duluth, GA). Six months later, she had a 4.9 x 4.0 mm epithelial defect with an underlying stromal infiltrate in the right eye. Cultures were positive for P. aeruginosa. The ulcer responded to fortified antibiotics and resolved in 30 days. Best-corrected visual acuity after resolution of the ulcer was 20/30. Increased oxygen permeability associated with silicone hydrogel contact lenses may reduce, but does not eliminate, the risk of pseudomonas keratitis. Studies have yet to quantify the risk of keratitis associated with daily wear of these lens materials. Further study is necessary to identify the risks of complications with daily wear of silicone hydrogel lenses and to determine which factors may contribute to those risks.
Peng, Cheng-Chun; Fajardo, Neil P; Razunguzwa, Trust; Radke, Clayton J
We developed an in vitro model-blink cell that reproduces the mechanism of in vivo fouling of soft contact lenses. In the model-blink cell, model tear lipid directly contacts the lens surface after forced aqueous rupture, mirroring the pre-lens tear-film breakup during interblink. Soft contact lenses are attached to a Teflon holder and immersed in artificial tear solution with protein, salts, and mucins. Artificial tear-lipid solution is spread over the air/tear interface as a duplex lipid layer. The aqueous tear film is periodically ruptured and reformed by withdrawing and reinjecting tear solution into the cell, mimicking the blink-rupture process. Fouled deposits appear on the lenses after cycling, and their compositions and spatial distributions are subsequently analyzed by optical microscopy, laser ablation electrospray ionization mass spectrometry, and two-photon fluorescence confocal scanning laser microscopy. Discrete deposit (white) spots with an average size of 20 to 300 μm are observed on the studied lenses, confirming what is seen in vivo and validating the in vitro model-blink cell. Targeted lipids (cholesterol) and proteins (albumin from bovine serum) are identified in the discrete surface deposits. Both lipid and protein occur simultaneously in the surface deposits and overlap with the white spots observed by optical microscopy. Additionally, lipid and protein penetrate into the bulk of tested silicone-hydrogel lenses, likely attributed to the bicontinuous microstructure of oleophilic silicone and hydrophilic polymer phases of the lens. In vitro spoilation of soft contact lenses is successfully achieved by the model-blink cell confirming the tear rupture/deposition mechanism of lens fouling. The model-blink cell provides a reliable laboratory tool for screening new antifouling lens materials, surface coatings, and care solutions.
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
Grobe, G L; Valint, P L; Ammon, D M
The surface chemistry and topography of cast-molded Etafilcon-A and doubled-sided lathed Etafilcon-A soft contact lenses were determined to be significantly different. The variations in surface chemical and morphologic structure between the two lenses were the result of contact lens manufacturing methods. The surface of the cast-molded Etafilcon-A had a consistently less rough surface compared to the doubled sided lathed Etafilcon-A as determined by atomic force microscopy. The surface of the doubled sided lathed Etafilcon-A contained primarily silicone and wax contamination in addition to minute amounts of HEMA. The cast-molded Etafilcon-A had an elemental and chemical content which was consistent with the polymer stoichiometry. Contact angle wettability profiles revealed inherent wettability differences between the two lenses types. The cast-molded Etafilcon-A had an inherently greater water wettability, polarity, and critical surface tension. This means that these two lenses cannot be compared as similar or identical lens materials in terms of surface composition. The manufacturing method used to produce a soft contact lens directly determines the surface elemental and chemical structure as well as the morphology of the finished lens material. These results suggest possible differences in the clinical comfort, spoilage, and lubricity felt during patient wear.
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
Varikooty, Jalaiah; Keir, Nancy; Richter, Doris; Jones, Lyndon W; Woods, Craig; Fonn, Desmond
To evaluate subjective ocular comfort across the day with three silicone hydrogel daily disposables (SHDDs) in a group of adapted lens wearers. Masked subjects (asymptomatic or symptomatic of end-of-day (EOD) dryness with habitual lenses) wore three SHDDs: DAILIES TOTAL1 (DT1), Clariti 1day (C1D), or 1-DAY ACUVUE TRUEYE (AVTE), each for 3 days. On day 2, wearing time (WT) and comfort ratings after insertion, at 4, 8, and 12 hours, and at EOD were recorded. Because not all subjects wore lenses for 12 hours, comfort was analyzed across the day (up to 8 hours, 8 to 12 hours), and a new variable ("cumulative comfort" [CC]) was calculated for EOD. One hundred four subjects completed the study (51 asymptomatic, 53 symptomatic). The two groups had different WTs (mean WT, 14.0 and 12.7 hours, respectively; p < 0.001). Ocular comfort was rated higher in the asymptomatic group throughout the day (p < 0.001). One hundred four subjects wore all three SHDDs for at least 8 hours, whereas 74 (45 asymptomatic, 29 symptomatic) subjects wore them for 12 hours or longer. Comfort ratings were higher with DT1 (least square means [LSM] = 91.0) than with C1D (LSM = 86.5; p < 0.001) and AVTE (LSM = 87.7; p = 0.011) for the first 8 hours and lower with C1D compared with DT1 (p = 0.012) from 8 to 12 hours. Mean EOD (± SD) comfort with the C1D lens was 72 ± 21, lower than both DT1 (mean, 79 ± 17; p = 0.001) and AVTE (mean, 78 ± 21; p = 0.010). Mean CC was higher in the asymptomatic group (mean, 1261 ± 59) compared with that in the symptomatic group (mean, 1009 ± 58; p < 0.001) and higher for DT1 (mean, 1184 ± 258) than C1D (mean, 1094 ± 318; p = 0.002) and AVTE (mean, 1122 ± 297; p = 0.046). All three SHDDs had average WTs of 12 hours or longer for 1 day. Comfort during the first 12 hours was highest with DT1 (similar to AVTE between 8 and 12 hours) and lowest with C1D. End-of-day comfort was lowest with C1D, and CC was highest for DT1. Cumulative comfort may be a valuable new
Park, Young Min; Kwon, Han Jo; Lee, Jong Soo
To determine the bacteriological spectrum of the removed therapeutic soft contact lenses (TSCLs) and to establish efficacy of prophylactic antibiotics on TSCLs used for 2 weeks for treatment of patients with recurrent corneal erosion syndrome (RCES). This study included idiopathic RCES treated using highly oxygen-permeable silicone hydrogel contact lenses (CLs), and treated 4 times per day with topical tobramycin 3% for 2 weeks. After TSCLs were applied for 2 weeks, the lenses were removed with sterile forceps under which a speculum was inserted, and placed on blood agar with the inner face down. The TSCLs were analyzed for bacterial colonization, and antibiotic susceptibility tests were performed for the isolates, using disk diffusion. Of the 40 lenses analyzed, 9 (22.5%) yielded positive cultures. Staphylococcus epidermidis was the most commonly isolated microorganism; there were five methicillin-sensitive coagulase-negative staphylococci and two methicillin-resistant coagulase-negative staphylococci. Furthermore, we found two lenses that were colonized by Enterobacter gergoviae and Citrobacter freundii. All cultured bacteria showed intermediate or complete sensitivity to ciprofloxacin, tigecycline, and tobramycin. Despite bacterial colonization in 9 CLs, no clinical signs of infectious keratitis were found in any of the patients with prophylactic topical tobramycin 3%. In case of using TSCLs for 2 weeks, tobramycin or ciprofloxacin may be useful as prophylactic topical antibiotics for preventing secondary corneal infections. Considering currently growing incidence of ciprofloxacin-resistant ocular isolates, tobramycin seems to be a reasonable prophylactic topical antibiotic susceptible broad spectrum of bacteria in clinics.
Temporarily implanted devices, such as drug-loaded contact lenses, are emerging as the preferred treatment method for ocular diseases like glaucoma. Localizing the delivery of glaucoma drugs, such as timolol maleate (TM), can minimize adverse effects caused by systemic administration. Although eye drops and drug-soaked lenses allow for local treatment, their utility is limited by burst release and a lack of sustained therapeutic delivery. Additionally, wet transportation and storage of drug-soaked lenses result in drug loss due to elution from the lenses. Here we present a nanodiamond (ND)-embedded contact lens capable of lysozyme-triggered release of TM for sustained therapy. We find that ND-embedded lenses composed of enzyme-cleavable polymers allow for controlled and sustained release of TM in the presence of lysozyme. Retention of drug activity is verified in primary human trabecular meshwork cells. These results demonstrate the translational potential of an ND-embedded lens capable of drug sequestration and enzyme activation. PMID:24506583
Cho, P; Woo, G C
Distance and near visual acuity of 13 low astigmats were determined in a double-masked experiment through thick and thin (centre thickness 0.12 mm and 0.06 mm, respectively) spherical lathe-cut soft lenses. For each lens type, distance and near LogMAR VA and over-refraction were assessed with different logMAR VA charts. For 70% of the subjects, the residual astigmatism was significantly lower than the refractive astigmatism with thicker lenses. No statistically significant differences in the distance and near logMAR VA was found between the two lens types using any of the charts used, though, in general, logMAR VA obtained through the thicker lens was better than logMAR VA through the thinner lens. The variabilities in distance and near logMAR VA between the two lens types increased with decreased contrast. The variabilities in distance logMAR VA were greater with Chinese charts than with English charts, and LogMAR VA with Chinese charts were significantly worse for both lens types. Based on the results of this study, we concluded that thicker spherical lathe-cut soft lenses provide better vision in low astigmats. The Snellen acuity test is inadequate for vision assessment of soft contact lens wearers. When a patient wearing thin soft contact lenses complains of poor vision in spite of 6/6 or 6/5 Snellen acuity, changing to thicker lenses may be considered.
Hill, J F
The purpose of this study was to compare the clinical acceptability of polymacon spin-cast to polymacon lathe-cut hydrophilic contact lenses. Ten patients successfully wearing polymacon spin-cast lenses were studied. Each patient had one eye refitted with polymacon lathe-cut lenses. Comparison of the two types of lenses was then made. Objective evaluation included centration, movement, visual acuity, and over-refraction. Subjective criteria were based on patient comfort and stability and quality of vision. Results indicate that lathe-cut lenses can be just as clinically satisfactory as the spincast ones.
Willcox, Mark; Sharma, Savitri; Naduvilath, Thomas J; Sankaridurg, Padmaja R; Gopinathan, Usha; Holden, Brien A
To determine whether carriage of microbes on the contact lens or ocular surfaces during extended wear (EW) with soft hydroxyethyl methacrylate (HEMA)-based contact lenses predisposes the wearer to adverse events. Participants (non-contact lens wearers) were enrolled in a clinical study involving wear of HEMA-based hydrogel lenses on a six night EW basis with weekly replacement. Type and number of bacteria colonizing the lower lid margins, upper bulbar conjunctiva, and contact lenses during EW after one night, 1 week, 1 month, and thereafter every 3 months for 3.5 years were determined. The association of bacteria with adverse responses was compared between carriers (defined as having significant microbes cultured from two or more samples with 1 year) and noncarriers, and the strength of the association was estimated using multivariate logistic regression. Carriers of gram-positive bacteria on lenses (particularly coagulase negative staphylococci or Corynebacterium spp.) were approximately three and eight times more likely to develop contact lens-induced peripheral ulcers (CLPUs) and asymptomatic infiltrates (AIs), respectively. Staphylococcus aureus was most frequently isolated from lenses during CLPU. Carriers of gram-negative bacteria on lenses were five times more likely to develop contact lens-induced acute red eye (CLARE). Haemophilus influenzae was isolated most frequently from lenses during CLARE and AI events. Bacterial carriage on contact lenses during EW predisposes the wearer to the development of corneal inflammatory events including CLARE, CLPU, and AI.
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
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%.
Dietze, Holger H; Cox, Michael J
Soft contact lenses produce a significant level of spherical aberration affecting their power on-eye. A simple model assuming that a thin soft contact lens aligns to the cornea predicts that these effects are similar on-eye and off-eye. The wavefront aberration for 17 eyes and 33 soft contact lenses on-eye was measured with a Shack-Hartmann wavefront sensor. The Zernike coefficients describing the on-eye spherical aberration of the soft contact lens were compared with off-eye ray-tracing results. Paraxial and effective lens power changes were determined. The model predicts the on-eye spherical aberration of soft contact lenses closely. The resulting power change for a +/- 7.00 D spherical soft contact lens is +/- 0.5 D for a 6-mm pupil diameter and +/- 0.1 D for a 3-mm pupil diameter. Power change is negligible for soft contact lenses corrected for off-eye spherical aberration. For thin soft contact lenses, the level of spherical aberration and the consequent power change is similar on-eye and off-eye. Soft contact lenses corrected for spherical aberration in air will be expected to be aberration-free on-eye and produce only negligibly small power changes. For soft contact lenses without aberration correction, for higher levels of ametropia and large pupils, the soft contact lens power should be determined with trial lenses with their power and p value similar to the prescribed lens. The benefit of soft contact lenses corrected for spherical aberration depends on the level of ocular spherical aberration.
Mowrey-McKee, Mary; Borazjani, Roya; Collins, Gary; Cook, James; Norton, Susan
The purpose of this article is to describe new methodology, antimicrobial efficacy endpoint methodology to determine compatibility of contact lens solutions, lens cases and hydrogel lenses for disinfection (AEEMC), to evaluate the effect of a contact lens and a lens case on disinfection efficacy, and to present the ring test used to justify the use of the method in multiple laboratories. A prototype solution containing chlorhexidine as the disinfecting agent and four representative lens types (group I and IV hydrogels and two silicone hydrogels) were used in these ring tests. Five laboratories participated in the chemical and microbiologic analyses. The residual chlorhexidine in lens cases containing the contact lenses was determined using high-performance liquid chromatography; uptake by the lenses was then determined by extrapolation. For the microbiologic part of the study, a contact lens was placed in the well of the lens case, inoculated at 10 to 10 cfu (colony forming units) per lens with microorganisms in 10% organic soil. The microorganisms, Pseudomonas aeruginosa, Serratia marcescens, Staphylococcus aureus, Candida albicans, and Fusarium solani, were prepared as in International Organization for Standardization (ISO) 14729. After a 3- to 10-min exposure time, the prototype solution was dispensed into each well. Aliquots of the inoculated solutions were removed at 4 and 24 hrs and 7 and 30 days and cultured in neutralizing media for determination of survivors; lenses were also cultured for survivors. Chemical uptake data confirmed the differences observed in kill of the challenge organisms according to lens type. It was observed that the culturing of the solution provided adequate data to show the effect of a lens on disinfection efficacy of a lens care product. The findings of the ring test indicated that the separate culturing of the contact lenses is not necessary for routine assessment. The methodology in the November 12, 2008, draft standard (AEEMC
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.
Williams, Timothy J; Schneider, Rene P; Willcox, Mark D P
Gram negative bacterial adhesion to contact lenses can cause adverse responses. During contact lens wear, components of the tear film adsorb to the contact lens. This study aimed to investigate the effect of this conditioning film on the viability of bacteria. Bacteria adhered to contact lenses which were either unworn, worn for daily-, extended- or overnight-wear or coated with lactoferrin or lysozyme. Numbers of viable and total cells were estimated. The number of viable attached cells was found to be significantly lower than the total number of cells on worn (50% for strain Paer1 on daily-wear lenses) or lactoferrin-coated lenses (56% for strain Paer1). Lysozyme-coated lenses no statistically significant effect on adhesion. The conditioning film gained through wear may not inhibit bacterial adhesion, but may act adversely upon those bacteria that succeed in attaching.
Efron, Nathan; Morgan, Philip B
Although the first silicone hydrogel contact lenses introduced onto the world contact lens market in 1999 held approval for both daily wear and extended wear use, the latter modality was promoted much more heavily by the manufacturers. The first silicone hydrogel lenses specifically promoted for daily wear were introduced in 2003. Data that we have gathered from annual contact lens fitting surveys demonstrate an immediate increase in market share whereby this lens type now represents more than one-third of soft lens fits in the United Kingdom. The success of this lens category is attributed to the health and safety benefits of silicone hydrogel materials and the positive impact of lens manufacturers by way of the effective marketing and distribution of these products.
Morgan, Philip B; Chamberlain, Paul; Moody, Kurt; Maldonado-Codina, Carole
To evaluate the performance of a silicone hydrogel daily disposable lens in neophyte subjects over 12 months. Seventy four subjects with no previous contact lens experience were randomised to wear narafilcon A (1 DAY ACUVUE(®) TruEye™) lenses (LW group) or to wear no contact lenses (NLW group) for 12 months. Biomicroscopy (performed by a masked investigator), visual acuity and subjective response scores were recorded at an initial visit and six follow-up visits, in addition to lens fit and surface evaluation for the LW group. Comfort was recorded with SMS messaging. Fifteen of the LW group discontinued before the end of the study, compared with six of the NLW group. Measured visual acuity was about half a line better for the NLW group as these subjects were provided with their full sphero-cylindrical over-refraction, compared to the LW group in their best spherical corrected contact lenses; subjective scores for vision were similar for the two groups. Bulbar conjunctival hyperaemia, limbal hyperaemia, corneal staining, conjunctival staining and papillary conjunctivitis were clinically equivalent for the two groups whereas conjunctival staining was higher in the LW group. Comfort scores assessed by SMS were equivalent for the LW and NLW groups; there was a measurable improvement in comfort during the first month of wear for the LW group. This work has demonstrated that modern soft lenses (narafilcon A daily disposable silicone hydrogel lenses) offer an excellent, comfortable form of vision correction, and are able to exhibit minimal alterations to ocular physiology. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
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.
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.
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.
Zimmerman, Aaron B; Marks, Amanda
To report a case of neurotrophic keratitis in which scleral contact lenses improved vision from 20/100 to 20/20, however, due to poor lens care, an incident of microbial keratitis developed. A 64-year-old man with an ocular history of neurotrophic keratitis secondary to herpes simplex in each eye was successfully fit with scleral lenses. He subsequently developed microbial keratitis due to a number of risk factors. The lesion was culture negative, yet was very responsive to treatment with moxifloxacin. The lesion fully healed, and the patient did not suffer additional vision loss. This case demonstrates the ability of scleral lenses to correct visual impairments secondary to poor epithelial integrity and illustrates the importance of the practitioner providing detailed lens care instruction.
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.
Myers, R I; Larsen, D W; Tsao, M; Castellano, C; Becherer, L D; Fontana, F; Ghormley, N R; Meier, G
The purposes of this study were to determine if the quantity of protein deposited (QPD) upon hydrogel lenses was affected by enzymatic cleaning and to test the potential relation between QPD and visible protein deposition (VPD) and change. Seventy-four contact lens patients classified as "heavy depositors" wore new lenses for an average of 80 (SD = 32) days. Cleaning and disinfection solutions varied. One lens was cleaned weekly by a papain enzymatic treatment. The distribution of QPD measurements was bimodal and was related to the FDA material for nonionic, low water content lenses (FDA Materials Group no. 1). The mean deposition was 45 micrograms/cm2 (N = 112) compared with that of ionic, high water content lenses (FDA Materials Group no. 4), which was 1010 micrograms/cm2 (N = 30). VPD distributions were the same for the FDA Group no. 1 and no. 4 lenses. Enzymatic treatment did not significantly reduce QPD; however, enzymatic treatment did reduce VPD. Thus QPD and VPD are independent phenomena and possible reasons for this are given.
Polse, Kenneth A
Robert B. Mandell is the quintessential modern clinical scientist. Over his long academic career, he has pioneered many advances in contact lens practice, ranging from a more complete understanding of corneal shape to the effects of contact lenses on corneal health. His classic text, Contact Lens Practice, first published in 1965, was reprinted 14 times in four editions up to 1988. Mandell's contributions to the advancement of the profession of optometry have always been characterized by a genuine concern for the patient and a steadfast belief that his research must have relevance to the practice of optometry.
Anstey, A; Taylor, D; Chalmers, I; Ansari, E
Nine brands of contact lens marketed as "UV protective" were tested for ultraviolet (UV) transmission in order to assess potential suitability for psoralen-sensitised patients. UV-transmission characteristics of hydrated lenses was tested with a Bentham monochromator spectro-radiometer system. All lenses showed minimal transmission loss in the visible band. The performance of the nine lenses was uniform for ultraviolet B radiation with negligible transmission, but showed variation in transmission for ultraviolet A radiation. None of the lenses complied with UV-transmission criteria used previously to assess UV-blocking spectacles. Only two lenses had UV-blocking characteristics which came close to the arbitrary criteria used. The performance of ordinary soft and hard lenses was very similar, with negligible blocking of UV radiation. None of the nine contact lenses marketed as "UV protective" excluded sufficient UVA to comply with criteria in current use to assess UV protection in spectacles for psoralen-sensitised patients. However, the improved UV-blocking characteristics of contact lenses identified in this paper compared to previous studies suggests that such a contact lens will soon become available. Meanwhile, contact lens-wearing systemically sensitised PUVA patients should continue to wear approved spectacles for eye protection whilst photosensitised with psoralen.
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
Schultz, Clyde; Breaux, Jason; Schentag, Jerome; Morck, Douglas
Despite pharmacological advances, delivery of drugs to the posterior segment of the eye remains problematic. We investigated the ability of hydrogel contact lenses to deliver small-molecule steroids, as well as larger biological molecules to the posterior segment. Release characteristics of steroid-instilled lenses were studied in vitro. Drug delivery to the posterior segment of the eye was evaluated in a rabbit model, in which hydrogel contact lenses treated with diluted steroids (prednisolone or beclomethasone) were placed on rabbit corneas for four hours on days 1, 2, 5, 8 and 10. The amount of drug in plasma, posterior segment tissue and vitreous humour was measured with high-performance liquid chromatography-tandem mass spectrometry. In a further preliminary investigation, two rabbits were treated with ranibizumab. The lenses released prednisolone and beclomethasone in saline over a six-hour period at a declining rate. Prednisolone was found in posterior segment tissue from six of six rabbits at concentrations ranging from 26.8 to 166 ng/g and in vitreous humour from two of six rabbits. Beclomethasone was detected in posterior segment tissue from three rabbits but was not found in the vitreous humour. Ranibizumab was detected in posterior segment tissue in a range from 0.19 ng/mL to 0.5183 ng/mL. Hydrogel contact lenses are a non-invasive, periocular drug delivery device capable of achieving measurable drug levels in posterior segment tissue. © 2010 The Authors. Clinical and Experimental Optometry © 2010 Optometrists Association Australia.
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
Szczesna, Dorota H
Evaluating precorneal tear film is one of important clinical measurements for assessing health of anterior eye. Contact lens wear is known to influence the quality of tear film. The aim was to evaluate the applicability of lateral shearing interferometry technique in the noninvasive assessment of the effects of contact lens replacement modality and its water content on tear film stability. Sixteen regular soft contact lens wearers took place in the study. Lateral shearing interferometry measurements, in suppressed blinking conditions, were taken in the mornings and afternoons, after a minimum of 5 hours of lens wear for the daily lenses, and after 2 weeks and 1 month for the fortnightly and monthly lens replacement modalities, respectively. Significant differences (paired bootstrap-based Behrens-Fisher test, P < 0.05) in the tear film surface quality were found between all considered pairs of replacement modalities except for the daily and fortnightly lenses measured in the afternoon of the first day of wear. Significant worsening (paired bootstrap-based Behrens-Fisher test, P < 0.001) of tear film quality was found for the low water content materials. Lateral shearing interferometry is a powerful method for the noninvasive assessment of tear film surface quality on soft contact lenses that may find, in future, its use in the clinical assessment of anterior eye's health.
Dumbleton, Kathryn; Keir, Nancy; Moezzi, Amir; Feng, Yunwei; Jones, Lyndon; Fonn, Desmond
Silicone hydrogel (SiH) lenses offer many physiological advantages for daily wear (DW) in addition to the continuous-wear modality for which they were originally developed. The purpose of this study was to investigate the clinical performance and physiological responses in a group of successful long-term wearers of conventional hydrogel lenses when refitted with DW SiH contact lenses. Eighty-seven successful soft lens wearers (8.4+/-4.7 years of prior lens wear) participated in this study. Bulbar and limbal hyperemia were subjectively graded and digitally photographed for subsequent masked objective evaluation. Subjective symptoms were scored using visual analog scales. In addition, refractive error, corneal curvature, and corneal thickness were measured. All subjects were refitted with Focus Night & Day (lotrafilcon A) SiH lenses; however, to reduce the potential for bias, they were informed that they were being randomly assigned to wear either low oxygen permeability (Dk) lenses or high Dk SiH lenses and were "masked" as to their lens assignment. Subjects returned after 1 week, 1 month, and 2 months of DW, at which time all gradings, photographs, and measurements were repeated. End-of-day subjective symptoms were also graded periodically during the study. Ninety-three percent of subjects were successfully refitted. Both objective and subjective evaluations showed that bulbar and limbal hyperemia decreased significantly in all quadrants during the study (p<0.001), particularly for those subjects with greater baseline hyperemia (p<0.001). Subjects reported a concurrent reduction in end-of-day dryness and improved end-of-day comfort compared with their habitual lenses (p<0.001). No significant changes in refractive error, tarsal papillary response, corneal curvature, or corneal thickness were found during the study. Hyperemia in contact lens wearers may be attributed to a number of factors, including hypoxia. Refitting existing low Dk lens wearers with SiH lenses on
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
Lorenz, Kathrine Osborn; Kakkassery, Joseph; Boree, Danielle; Pinto, David
Background Limbal ring (also known as ‘circle’) contact lenses are becoming increasingly popular, especially in Asian markets because of their eye-enhancing effects. The pigment particles that give the eye-enhancing effects of these lenses can be found on the front or back surface of the contact lens or ‘enclosed’ within the lens matrix. The purpose of this research was to evaluate the pigment location and surface roughness of seven types of ‘circle’ contact lenses. Methods Scanning electron microscopic (SEM) analysis was performed using a variable pressure Hitachi S3400N instrument to discern the placement of lens pigments. Atomic force microscopy (Dimension Icon AFM from Bruker Nano) was used to determine the surface roughness of the pigmented regions of the contact lenses. Atomic force microscopic analysis was performed in fluid phase under contact mode using a Sharp Nitride Lever probe (SNL-10) with a spring constant of 0.06 N/m. Root mean square (RMS) roughness values were analysed using a generalised linear mixed model with a log-normal distribution. Least square means and their corresponding 95% confidence intervals were estimated for each brand, location and pigment combination. Results SEM cross-sectional images at 500× and 2,000× magnification showed pigment on the surface of six of the seven lens types tested. The mean depth of pigment for 1-DAY ACUVUE DEFINE (1DAD) lenses was 8.1 μm below the surface of the lens, while the remaining lens types tested had pigment particles on the front or back surface. Results of the atomic force microscopic analysis indicated that 1DAD lenses had significantly lower root mean square roughness values in the pigmented area of the lens than the other lens types tested. Conclusions SEM and AFM analysis revealed pigment on the surface of the lens for all types tested with the exception of 1DAD. Further research is required to determine if the difference in pigment location influences on-eye performance. PMID
Cole, Nerida; Hume, Emma B H; Vijay, Ajay K; Sankaridurg, Padmaja; Kumar, Naresh; Willcox, Mark D P
One strategy to minimize bacteria-associated adverse responses such as microbial keratitis, contact lens-induced acute red eye (CLARE), and contact lens induced peripheral ulcers (CLPUs) that occur with contact lens wear is the development of an antimicrobial or antiadhesive contact lens. Cationic peptides represent a novel approach for the development of antimicrobial lenses. A novel cationic peptide, melimine, was covalently incorporated into silicone hydrogel lenses. Confirmation tests to determine the presence of peptide and anti-microbial activity were performed. Cationic lenses were then tested for their ability to prevent CLPU in the Staphylococcus aureus rabbit model and CLARE in the Pseudomonas aeruginosa guinea pig model. In the rabbit model of CLPU, melimine-coated lenses resulted in significant reductions in ocular symptom scores and in the extent of corneal infiltration (P < 0.05). Evaluation of the performance of melimine lenses in the CLARE model showed significant improvement in all ocular response parameters measured, including the percentage of eyes with corneal infiltrates, compared with those observed in the eyes fitted with the control lens (P < or = 0.05). Cationic coating of contact lenses with the peptide melimine may represent a novel method of prevention of bacterial growth on contact lenses and consequently result in reduction of the incidence and severity of adverse responses due to Gram-positive and -negative bacteria during lens wear.
Gause, Samuel; Hsu, Kuan-Hui; Shafor, Chancellor; Dixon, Phillip; Powell, Kristin Conrad; Chauhan, Anuj
Ophthalmic drug for the anterior chamber diseases are delivered into tears by either eye drops or by extended release devices placed in the eyes. The instilled drug exits the eye through various routes including tear drainage into the nose through the canaliculi and transport across various ocular membranes. Understanding the mechanisms relevant to each route can be useful in predicting the dependency of ocular bioavailability on various formulation parameters, such as drug concentration, salinity, viscosity, etc. Mathematical modeling has been developed for each of the routes and validated by comparison with experiments. The individual models can be combined into a system model to predict the fraction of the instilled drug that reaches the target. This review summarizes the individual models for the transport of drugs across the cornea and conjunctiva and the canaliculi tear drainage. It also summarizes the combined tear dynamics model that can predict the ocular bioavailability of drugs instilled as eye drops. The predictions from the individual models and the combined model are in good agreement with experimental data. Both experiments and models predict that the corneal bioavailability for drugs delivered through eye drops is less than 5% due to the small area of the cornea in comparison to the conjunctiva, and the rapid clearance of the instilled solution by tear drainage. A contact lens is a natural choice for delivering drugs to the cornea due to the placement of the contact in the immediate vicinity of the cornea. The drug released by the contact towards the cornea surface is trapped in the post lens tear film for extended duration of at least 30min allowing transport of a large portion into the cornea. The model predictions backed by in vivo animal and clinical data show that the bioavailability increases to about 50% with contact lenses. This realization has encouraged considerable research towards delivering ocular drugs by contact lenses. Commercial
Costa, Manuel F. M.
Optical triangulation as a non-destructive test method extensively proved its usefulness on the dimensional and topographic inspection of a large range of objects and surfaces. In this communication the issue of microtopographic and thickness inspection of hard contact lenses (RPG) is addressed. The use of optical triangulation is discussed based on the results of the application of our MICROTOP.03.MFC microtopographer to this kind of tasks will be presented.
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.
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
Zeri, Fabrizio; De Cusatis, Mario; Lupelli, Luigi; Swann, Peter Graham
To investigate if the accuracy of intraocular pressure (IOP) measurements using rebound tonometry over disposable hydrogel (etafilcon A) contact lenses (CL) is affected by the positive power of the CLs. The experimental group comprised 26 subjects, (8 male, 18 female). IOP measurements were undertaken on the subjects' right eyes in random order using a Rebound Tonometer (ICare). The CLs had powers of +2.00D and +6.00D. Measurements were taken over each contact lens and also before and after the CLs had been worn. The IOP measure obtained with both CLs was significantly lower compared to the value without CLs (t test; p<0.001) but no significant difference was found between the two powers of CLs. Rebound tonometry over positive hydrogel CLs leads to a certain degree of IOP underestimation. This result did not change for the two positive lenses used in the experiment, despite their large difference in power and therefore in lens thickness. Optometrists should bear this in mind when measuring IOP with the rebound tonometer over plus power contact lenses. Copyright © 2016 The Authors. Published by Elsevier Espana.. All rights reserved.
Sandri, Giuseppina; Bonferoni, Maria Cristina; Rossi, Silvia; Delfino, Alessio; Riva, Federica; Icaro Cornaglia, Antonia; Marrubini, Giorgio; Musitelli, Giorgio; Del Fante, Claudia; Perotti, Cesare; Caramella, Carla; Ferrari, Franca
Hemoderivative tear substitutes contain various ephiteliotrophic factors, such as growth factors (GF), involved in ocular surface homeostasis without immunogenic properties. The aim of the present work was the loading of platelet lysate into contact lenses to improve the precorneal permanence of platelet lysate growth factors on the ocular surface to enhance the treatment of corneal lesions. To this purpose, chondroitin sulfate, a sulfated glycosaminoglycan, which is normally present in the extracellular matrix, was associated with platelet lysate. In fact, chondroitin sulfate is capable of electrostatic interaction with positively charged growth factors, in particular, with bFGF, IGF, VEGF, PDGF and TGF-β, resulting in their stabilization and reduced degradation in solution. In the present work, various types of commercially available contact lenses have been loaded with chondroitin sulfate or chondroitin sulfate in association with platelet lysate to achieve a release of growth factors directly onto the corneal surface lesions. One type of contact lenses (PureVision(®)) showed in vitro good proliferation properties towards corneal cells and were able to enhance cut closure in cornea constructs. Copyright © 2016 Elsevier B.V. All rights reserved.
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.
Mochizuki, Hiroshi; Yamada, Masakazu; Hatou, Shin; Kawashima, Motoko; Hata, Seiichiro
Recent studies have shown that low tear phospholipid levels are associated with tear film instability in hydrophilic contact lens wearers. The concentration of secretory phospholipase A2 (sPLA2), the enzyme that hydrolyzes phospholipids, in tears is known to exceed the levels found in serum by four orders of magnitude. This study was performed to determine the levels of sPLA2 from the deposition on two different frequent-replacement contact lens materials. Polymacon and etafilcon A contact lenses worn for 2 weeks by 16 experienced contact lens wearers were used for the analysis. Total lipids were determined by the sulfo-phospho-vanillin reaction. Phospholipids in lipid extracts were estimated by phosphorus determination with ammonium molybdate through enzymatic digestion. Total protein was measured by bicinchoninic acid analysis. Double-antibody sandwich enzyme-linked immunosorbent assay was used to determine sPLA2 concentrations. Total lipid deposition was found to be greater in the polymacon group (66.3+/-16.3 microg/lens) than in the etafilcon A group, although phospholipids were not detected in either group. The etafilcon A group had greater deposition of protein (3.7+/-0.7 mg/lens) than the polymacon group had. The etafilcon A group deposited statistically significantly more group IIa sPLA2 (1.1+/-0.3 microg/lens) than the polymacon group (0.07+/-0.04 microg/lens) did (P<0.001). There was a significant difference in the lipid and protein deposition profiles in the two lenses tested. A significant amount of sPLA2 in the deposition on contact lenses may play a role in tear film instability in hydrophilic contact lens wearers.
Nilagiri, Vinay Kumar; Metlapally, Sangeetha; Kalaiselvan, Parthasarathi; Schor, Clifton M; Bharadwaj, Shrikant R
This study showed an improvement in three-dimensional depth perception of subjects with bilateral and unilateral keratoconus with rigid gas-permeable (RGP) contact lens wear, relative to spectacles. This novel information will aid clinicians to consider RGP contact lenses as a management modality in keratoconic patients complaining of depth-related difficulties with their spectacles. The aim of this study was to systematically compare changes in logMAR acuity and stereoacuity from best-corrected spherocylindrical spectacles to RGP contact lenses in bilateral and unilateral keratoconus vis-à-vis age-matched control subjects. Monocular and binocular logMAR acuity and random-dot stereoacuity were determined in subjects with bilateral (n = 30; 18 to 24 years) and unilateral (n = 10; 18 to 24 years) keratoconus and 20 control subjects using standard psychophysical protocols. Median (25th to 75th interquartile range) monocular (right eye) and binocular logMAR acuity and stereoacuity improved significantly from spectacles to RGP contact lenses in the bilateral keratoconus cohort (P < .001). Only monocular logMAR acuity of affected eye and stereoacuity improved from spectacles to RGP contact lenses in the unilateral keratoconus cohort (P < .001). There was no significant change in the binocular logMAR acuity from spectacles to RGP contact lenses in the unilateral keratoconus cohort. The magnitude of improvement in binocular logMAR acuity and stereoacuity was also greater for the bilateral compared with the unilateral keratoconus cohort. All outcome measures of cases with RGP contact lenses remained poorer than control subjects (P < .001). Binocular resolution and stereoacuity improve from spectacles to RGP contact lenses in bilateral keratoconus, whereas only stereoacuity improves from spectacles to RGP contact lenses in unilateral keratoconus. The magnitude of improvement in visual performance is greater for the binocular compared with the unilateral keratoconus cohort.
7RD-R1BS 579 A LONG TERM STUDY OF THE HATER CONTENT CHANGES IN THREE 1/2 TYPES OF HYDROGEL ..(U) AIR FORCE INST OF TECH URIGHT-PATTERSON AFI OH L 0...The Water Content Changes THESIS/Dl$$XF$T$77q Ln ~In Three Types Of Hydrogel Contact Lenses G EFRIGI EOTNME IO 7. AUTHOR(.) S. CONTRACT OR GRANT NUMBER...SECURITY CLASSIFICATION OF THIS PAGE ("o~tn Date Entered) ABSTRACT A" Sufficient oxygen is required to pass through a hydrogel contact lens for proper
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 (cm 2 /s) (mL O 2 /mL·mmHg) at 35°C. This was within ±20% tolerance range as specified in ISO 18369-2:2012(E) for the edge-corrected Dk of the nonpigmented etafilcon A control lens evaluated during the same session, 19.5×10 -11 (cm 2 /s) (mL O 2 /mL·mmHg). The edge-corrected Dk values of the lenses packaged with PVP (mean 20.1, standard deviation [SD] 0.3) were also within the ±20% tolerance range compared to those packaged without PVP (mean 20.0, SD 0.3). The pigment colorant and PVP embedded in the contact lens during autoclaving were not found to
Bonanno, Joseph A.; Clark, Christopher; Pruitt, John; Alvord, Larry
Purpose To determine the tear oxygen tension under a variety of conventional and silicone hydrogel contact lenses in human subjects. Methods Three hydrogel and five silicone hydrogel lenses (Dk/t = 17 to 329) were coated on the back surface with an oxygen sensitive, bovine serum albumin-Pd meso-tetra (4-carboxyphenyl) porphine complex (BSA-porphine). Each lens type was placed on the right eye of 15 non-contact lens wearers to obtain a steady-state open eye tear oxygen tension using oxygen sensitive phosphorescence decay of BSA-porphine. A closed-eye oxygen tension estimate was obtained by measuring the change in tear oxygen tension after 5 min of eye closure. In separate experiments, a goggle was placed over the lens wearing eye and a gas mixture (PO2 = 51 torr) flowed over the lens to simulate anterior lens oxygen tension during eye closure. Results Mean open eye oxygen tension ranged from 58 to 133 torr. Closed eye estimates ranged from 11 to 42 torr. Oxygen tension under the goggle ranged from 8 to 48 torr and was higher than the closed eye estimate for six out of the eight lenses, suggesting that the average closed eye anterior lens surface oxygen tension is <51 torr. For Dk/t >30, the measured tear oxygen tension is significantly lower than that predicted from previous studies. Conclusions The phosphorescence decay methodology is capable of directly measuring the in vivo post lens PO2 of high Dk/t lenses without disturbing the contact lens or cornea. Our data indicate that increasing Dk/t up to and beyond 140 continues to yield increased flux into the central cornea. PMID:19609230
Bonanno, Joseph A; Clark, Christopher; Pruitt, John; Alvord, Larry
To determine the tear oxygen tension under a variety of conventional and silicone hydrogel contact lenses in human subjects. Three hydrogel and five silicone hydrogel lenses (Dk/t = 17 to 329) were coated on the back surface with an oxygen sensitive, bovine serum albumin-Pd meso-tetra (4-carboxyphenyl) porphine complex (BSA-porphine). Each lens type was placed on the right eye of 15 non-contact lens wearers to obtain a steady-state open eye tear oxygen tension using oxygen sensitive phosphorescence decay of BSA-porphine. A closed-eye oxygen tension estimate was obtained by measuring the change in tear oxygen tension after 5 min of eye closure. In separate experiments, a goggle was placed over the lens wearing eye and a gas mixture (PO2 = 51 torr) flowed over the lens to simulate anterior lens oxygen tension during eye closure. Mean open eye oxygen tension ranged from 58 to 133 torr. Closed eye estimates ranged from 11 to 42 torr. Oxygen tension under the goggle ranged from 8 to 48 torr and was higher than the closed eye estimate for six out of the eight lenses, suggesting that the average closed eye anterior lens surface oxygen tension is <51 torr. For Dk/t >30, the measured tear oxygen tension is significantly lower than that predicted from previous studies. The phosphorescence decay methodology is capable of directly measuring the in vivo post lens PO2 of high Dk/t lenses without disturbing the contact lens or cornea. Our data indicate that increasing Dk/t up to and beyond 140 continues to yield increased flux into the central cornea.
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.
Mathews, Steven M; Spallholz, Julian E; Grimson, Mark J; Dubielzig, Richard R; Gray, Tracy; Reid, Ted W
Although silicone hydrogel materials have produced many corneal health benefits to patients wearing contact lenses, bacteria that cause acute red eye or corneal ulcers are still a concern. A coating that inhibits bacterial colonization while not adversely affecting the cornea should improve the safety of contact lens wear. A covalent selenium (Se) coating on contact lenses was evaluated for safety using rabbits and prevention of bacterial colonization of the contact lenses in vitro. Contact lenses coated with Se were worn on an extended-wear schedule for up to 2 months by 10 New Zealand White rabbits. Corneal health was evaluated with slit-lamp biomicroscopy, pachymetry, electron microscopy, and histology. Lenses worn by the rabbits were analyzed for protein and lipid deposits. In addition, the ability of Se to block bacterial colonization was tested in vitro by incubating lenses in a Pseudomonas aeruginosa broth followed by scanning electron microscopy of the contact lens surface. The covalent Se coating decreased bacterial colonization in vitro while not adversely affecting the corneal health of rabbits in vivo. The Se coating produced no noticeable negative effects as observed with slit-lamp biomicroscopy, pachymetry, electron microscopy, and histology. The Se coating did not affect protein or lipid deposition on the contact lenses. The data from this pilot study suggest that a Se coating on contact lenses might reduce acute red eye and bacterial ulceration because of an inhibition of bacterial colonization. In addition, our safety tests suggest that this positive effect can be produced without an adverse effect on corneal health.
Vijay, Ajay Kumar; Willcox, Mark D P
Contact lens cases become contaminated with microbes during use. We wished to compare the adhesion of uncommon bacterial contaminants isolated from lens cases to contact lenses with and without organic soil. Strains of Delftia acidovorans (001), Stenotrophomonas maltophilia (002 and 006), and Achromobacter xylosoxidans (001) isolated from contact lens cases (test strains) and Pseudomonas aeruginosa (Paer1) isolated from eyes at the time of infiltrative response (control strain) were used. Bacteria were grown and resuspended in phosphate-buffered saline (PBS) or 10% organic soil (heat-killed Saccharomyces cerevisiae resuspended in complement inactivated bovine serum). Two silicone hydrogel (senofilcon A and comfilcon A) and one hydrogel lens (etafilcon A) lens materials were used. Bacteria (1.0×10 and 1.0×10 colony-forming units/mL; CFU/mL) adhered to lenses for 24 hr and the numbers of bacteria adherent to each lens type (with and without organic soil) were estimated by culture. All the four test strains adhered in significantly greater numbers to contact lenses after incubation in inoculum prepared with organic soil compared with PBS-D. acidovorans 001 (0.7 log10 CFU; P<0.05), S. maltophilia 002 (1.7 log10 CFU; P<0.05), S. maltophilia 006 (0.9 log10 CFU; P<0.05), and A. xylosoxidans 001 (0.4 log10 CFU; P<0.05). However, the presence of organic soil did not increase adhesion of P. aeruginosa Paer1 (-0.1 log10 CFU; P>0.05). Achromobacter xylosoxidans 001 (P<0.01), D. acidovorans 001 (P<0.01), and S. maltophilia 002 (P<0.01) significantly differed in their adhesion to the three contact lens materials. Bacteria that are commonly found in contact lens cases adhered to contact lenses in relatively high numbers in the presence of organic soil. This might indicate that a similar phenomenon occurs in the presence of tears. This may facilitate their transfer from the lens to the cornea and the production of corneal infiltrates.
Thite, Nilesh; Shah, Ukti; Mehta, Jasmin; Jurkus, Janice
Purpose To understand the potential barriers, motivators and enablers in dispensing multifocal contact lenses (MFCL). Method Two focus group discussions were conducted to design questionnaires regarding the prescribing habits for multifocal contact lenses (MFCL). Questions on potential barriers and motivators were included. The questionnaires were distributed among 133 eye care practitioners across Mumbai, India. Practitioners fitting one or less patient per month with MFCL completed the survey describing potential barriers, while those who prescribed more MFCL's per month completed the survey describing enablers and motivators. Results Responses from 102 practitioners were received. Most common potential barriers in prescribing MFCL were increased chair time (75%), lack of readily available trials (69%) and limitation in power range (63%). Lack of awareness among patients (90%) was the most common barrier from patients’ outlook. Professional satisfaction (88%) and better business proposition (82%) were observed as main motivators while availability of the trials (84%) and correct patient selection (82%) were the major enablers. Graduate Optometrists felt dispensing MFCL did not offer a good business proposition (p = 0.02). Experienced practitioners were observed to be least motivated (p = 0.01) and believed that their patients found these lenses expensive (p = 0.02). Conclusion To enhance the MFCL practice, barriers like lack of awareness and limitations in power range must be addressed. Trial lens availability may motivate practitioners to prescribe MFCL. Further probing is required to understand lack of motivation among experienced practitioners. PMID:25563404
Thite, Nilesh; Shah, Ukti; Mehta, Jasmin; Jurkus, Janice
To understand the potential barriers, motivators and enablers in dispensing multifocal contact lenses (MFCL). Two focus group discussions were conducted to design questionnaires regarding the prescribing habits for multifocal contact lenses (MFCL). Questions on potential barriers and motivators were included. The questionnaires were distributed among 133 eye care practitioners across Mumbai, India. Practitioners fitting one or less patient per month with MFCL completed the survey describing potential barriers, while those who prescribed more MFCL's per month completed the survey describing enablers and motivators. Responses from 102 practitioners were received. Most common potential barriers in prescribing MFCL were increased chair time (75%), lack of readily available trials (69%) and limitation in power range (63%). Lack of awareness among patients (90%) was the most common barrier from patients' outlook. Professional satisfaction (88%) and better business proposition (82%) were observed as main motivators while availability of the trials (84%) and correct patient selection (82%) were the major enablers. Graduate Optometrists felt dispensing MFCL did not offer a good business proposition (p=0.02). Experienced practitioners were observed to be least motivated (p=0.01) and believed that their patients found these lenses expensive (p=0.02). To enhance the MFCL practice, barriers like lack of awareness and limitations in power range must be addressed. Trial lens availability may motivate practitioners to prescribe MFCL. Further probing is required to understand lack of motivation among experienced practitioners. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.
Burnham, Geoffrey W; Cavanagh, H Dwight; Robertson, Danielle M
To evaluate neutrophil-enhanced Pseudomonas aeruginosa (PA) biofilm formation on silicone hydrogel contact lenses and to determine the effect of epithelial biodebris on PA adherence in contact lens storage cases. A fully invasive PA corneal isolate stably conjugated to green fluorescent protein was used. Unworn lotrafilcon A contact lenses were incubated at various ratios of PA to polymorphonuclear neutrophil (PMN) for 24 hours at 37°C. Lens-associated PA was evaluated using laser scanning confocal microscopy and nonviable PA were visualized using propidium iodide. Viable bacteria were enumerated by colony-forming unit (CFU) analysis. For acute epithelial cell studies, PA viability was determined after coincubation with freeze-thaw epithelial cell lysates in 96-well polystyrene plates. Levels of residual cellular debris and bacterial viability were further assessed in used contact lens storage cases. Laser scanning confocal microscopy demonstrated that cotreatment with PMA-stimulated neutrophils increased PA adherence over 24 hours to lens surfaces with a striking alteration of PA architecture. Propidium iodide staining showed that the adherent bacteria consisted of a mixture of viable and nonviable PA; a PMN-associated increase in viable PA was confirmed by CFU (PA:PMN 0.1:1, P = 0.025; PA:PMN 1:1, P = 0.005). Acute epithelial cell debris studies revealed a significant increase in viable PA in 96-well plates in the presence of epithelial freeze-thaw lysates (PA:debris 1:1, P = 0.002; PA:debris 100:1, P = 0.002). Crystal violet staining of used lens storage cases revealed residual cellular debris at all time points, which was independent of microbial contamination; all lens cases used for periods of 9 months or more were uniformly associated with high levels of viable microorganisms. These results demonstrate that prolonged corneal inflammation with the presence of PMNs when confronted with simultaneous PA challenge in extended contact lens wear has the potential
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.
Tavazzi, Silvia; Tonveronachi, Martina; Fagnola, Matteo; Cozza, Federica; Ferraro, Lorenzo; Borghesi, Alessandro; Ascagni, Miriam; Farris, Stefano
The purpose of this study was a comparison between new and worn siloxane-hydrogel contact lenses in terms of microscopic structure, surface morphology, and loading of hyaluronan. The analyses were performed by scanning electron microscopy, with the support of the freeze-drying technique, and by fluorescence confocal microscopy. Along the depth profile of new lenses, a thin porous top layer was observed, which corresponds to the region of hyaluronan penetration inside well-defined channels. The time evolution was followed from one day to two weeks of daily wear, when a completely different scenario was found. Clear experimental evidence of a buggy surface was observed with several crests and regions of swelling, which could be filled by the hyaluronan solution. The modifications are attributed to the progressive relaxation of the structure of the polymeric network. © 2014 Wiley Periodicals, Inc.
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
Maciejewska, Magdalena; Bauer, Marta; Neubauer, Damian; Kamysz, Wojciech; Dawgul, Malgorzata
The widespread use of contact lenses is associated with several complications, including ocular biofilm-related infections. They are very difficult to manage with standard antimicrobial therapies, because bacterial growth in a biofilm is associated with an increased antibiotic resistance. The principal aim of this study was to evaluate the efficacy of antimicrobial peptides (AMPs) in eradication of bacterial biofilms formed on commercially available contact lenses. AMPs were synthesized according to Fmoc/tBu chemistry using the solid-phase method. Minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) of the compounds were determined. Anti-biofilm activity of the antimicrobial peptides determined at different temperatures (25 °C and 37 °C) were compared with the effectiveness of commercially available contact lens solutions. All of the tested compounds exhibited stronger anti-biofilm properties as compared to those of the tested lens solutions. The strongest activity of AMPs was noticed against Gram-positive strains at a temperature of 25 °C. Conclusions: The results of our experiments encourage us toward further studies on AMPs and their potential application in the prophylaxis of contact lens-related eye infections. PMID:28773992
Porcar, Esteban; Montalt, Juan Carlos; España-Gregori, Enrique; Peris-Martínez, Cristina
To analyse the visual quality achieved by fitting corneo-scleral contact lenses (CScL) in an uncommon case of bilateral keratoconus, high hyperopia and astigmatism. A 45-year-old man presented for eye examination due to the unsatisfactory quality of his vision wearing soft toric contact lenses. He presented high hyperopia and astigmatism with bilateral keratoconus. He was fitted with CScL to correct his irregular astigmatism and ocular aberrations. A diagnostic trial set was used in the fitting process and he was assessed according to standardised fitting methodology. Visual acuity, corneal topography, biometry and ocular aberrations were evaluated. The follow-up period was 1year. The best spectacle-corrected visual acuity was 20/32 with +8.00/-4.50×30° for the right eye (RE) and 20/25 with +7.75/-2.25×120° for the left eye (LE). After CScL fitting, visual acuity was improved to 20/20 and 20/16 for the RE and LE, respectively. The patient wore these contact lenses an average of 13h a day. The total high order aberrations decreased by approximately 79% in the RE (2.37-0.50μm) and 47% in the LE (1.04-0.55μm) after CScL fitting. Visual quality and wearing time were maintained after 1year wearing CScL. In addition, no adverse ocular effects were found during this period. The present case report describes how the patient had CScL fitted successfully for management of keratoconus with high hyperopia and astigmatism. They provided optimal visual quality, along with prolonged use times and no adverse effects to the cornea. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Dixon, Phillip; Fentzke, Richard C; Bhattacharya, Arnab; Konar, Aditya; Hazra, Sarbani; Chauhan, Anuj
Cystinosis is an orphan disease caused by a genetic mutation that leads to deposition of cystine crystals in many organs including cornea. Ophthalmic manifestation of the disease can be treated with hourly instillation of cysteamine eye drops. The hourly eye drop instillation is tedious to the patients leading to poor compliance and additionally, significant degradation of the drug occurs within one week of opening the bottle, which further complicates this delivery approach. This paper focuses on designing a contact lens to treat the disease with improved efficacy compared to eye drops, and also exploring safety of the drug eluding contact lens in an animal model. Our goal is to design a lens that is safe and that can deliver a daily therapeutic dose of cysteamine to the cornea while retaining drug stability. We show that cysteamine diffuses out rapidly from all lenses due to its small size. Vitamin E incorporation increases the release duration of both ACUVUE ® OASYS ® and ACUVUE ® TruEye TM but the effect is more pronounced in TruEye TM likely due to the low solubility of vitamin E in the lens matrix and higher aspect ratio of the barriers. The barriers are not effective in hydrogel lenses, which along with the high aspect ratio in silicone hydrogels suggests that barriers could be forming at the interface of the silicone and hydrogel phases. The presence of vitamin E has an additional beneficial effect of reduction in the oxidation rates, likely due to a transport barrier between the oxygen diffusing through the silicone channels and drug located in the hydrogel phase. Based on this study, both Acuvue ® OASYS ® and ACUVUE ® TruEye TM can be loaded with vitamin E to design a cysteamine eluting contact lenses for effective therapy of cystinosis. The lenses must be worn for about 4-5 hr. each day, which is less than the typical duration of daily-wear. The vitamin E and cysteamine loaded lenses did not exhibit any toxicity in a rabbit model over a period of 7
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.
Koh, Shizuka; Maeda, Naoyuki; Hamano, Takashi; Hirohara, Yoko; Mihashi, Toshifumi; Hori, Yuichi; Hosohata, Jun; Fujikado, Takashi; Tano, Yasuo
To investigate whether the polymer composition of disposable soft contact lenses affects sequential changes in higher-order aberrations (HOAs). Fifteen subjects who wore disposable soft contact lenses with dryness-related symptoms and 15 non-contact lens wearers were enrolled in this study. Ocular HOAs were measured for 60 seconds in each subject wearing a disposable etafilcon A lens (conventional lens) or a disposable etafilcon A lens with polyvinyl pyrrolidone (PVP) (lens with PVP) after 1 hour of contact lens wear. During the measurement, subjects were forced to blink every 10 seconds. The aberration data were analyzed in the central 4-mm diameter up to the sixth-order Zernike polynomials. Total HOAs, the fluctuation index (FI), and the stability index (SI) of the total HOAs over time were compared between the two groups. The subjective ocular dryness also was scored. In symptomatic wearers of disposable soft contact lenses, the total HOAs, the FI, and the SI with the lens with PVP were significantly (P=0.013, P=0.014, P=0.019, respectively) lower than with the conventional lens, whereas a significant (P=0.018) difference between the two lenses was observed only in the FI in non-contact lens wearers. Subjective ocular dryness with the lens with PVP significantly decreased compared with the conventional lens in both groups. Sequential measurement of HOAs may be a useful objective method to evaluate the effect of internal lubricating agents of disposable soft contact lenses on optical quality.
Zhao, Zhenjun; Fu, Han; Skotnitsky, Cheryl C; Sankaridurg, Padmaja R; Willcox, Mark D P
To investigate whether the level of IgE is increased in the eyes of patients during general contact lens-induced papillary conjunctivitis (CLPC) events, which involve enlarged papillae across the entire palpebral conjunctiva, or local CLPC events, in which papillae are confined to one or two parts of the area. Worn contact lenses were collected and soaked in phosphate-buffered saline. The levels of eluted IgE and IgE retained on contact lenses were detected by enzyme-linked immunosorbent assay. IgE was detected in 6 of 12 cases of general CLPC, 8 of 21 cases of local CLPC, and none of 14 control contact lenses. The average level of eluted IgE was 0.54 +/- 1.06 IU/contact lens, 0.28 +/- 0.54 IU/contact lens, and 0.04 +/- 0.06 IU/contact lens for general CLPC, local CLPC, and the control group, respectively. The incidences of positive IgE were significantly higher in patients with CLPC (general and local) than in control subjects, but no statistical difference was found between general and local CLPC. Generally higher amounts of retained IgE were detected on contact lenses that had increased levels of eluted IgE. Contact lenses that were collected before or after a CLPC event did not show increased levels of IgE. The level of IgE is increased in the eyes of some patients during an acute event of CLPC. The similar incidence of IgE-positive cases and levels of IgE from general and local CLPC contact lenses suggest that the conditions may share similar causal pathways.
Papas, Eric; Dahms, Anne; Carnt, Nicole; Tahhan, Nina; Ehrmann, Klaus
To investigate the manner in which contemporary soft contact lenses differ in the distribution of optical power within their optic zones and establish if these variations affect the vision of wearers or the prescribing procedure for back vertex power (BVP). By using a Visionix VC 2001 contact lens power analyzer, power profiles were measured across the optic zones of the following contemporary contact lenses ACUVUE 2, ACUVUE ADVANCE, O2OPTIX, NIGHT & DAY and PureVision. Single BVP measures were obtained using a Nikon projection lensometer. Visual performance was assessed in 28 masked subjects who wore each lens type in random order. Measurements taken were high and low contrast visual acuity in normal illumination (250 Cd/m), high contrast acuity in reduced illumination (5 Cd/m), subjective visual quality using a numerical rating scale, and visual satisfaction rating using a Likert scale. Marked differences in the distribution of optical power across the optic zone were evident among the lens types. No significant differences were found for any of the visual performance variables (p > 0.05, analysis of variance with repeated measures and Friedman test). Variations in power profile between contemporary soft lens types exist but do not, in general, result in measurable visual performance differences in the short term, nor do they substantially influence the BVP required for optimal correction.
Ribeiro, Andreza Maria; Figueiras, Ana; Veiga, Francisco
Conventional ophthalmic systems present very low corneal systemic bioavailability due to the nasolacrimal drainage and the difficulty to deliver the drug in the posterior segment of ocular tissue. For these reasons, recent advances have focused on the development of new ophthalmic drug delivery systems. This review provides an insight into the various constraints associated with ocular drug delivery, summarizes recent findings in soft contact lenses (SCL) and the applications of novel pharmaceutical systems for ocular drug delivery. Among the new therapeutic approaches in ophthalmology, SCL are novel continuous-delivery systems, providing high and sustained levels of drugs to the cornea. The tendency of research in ophthalmic drug delivery systems development are directed towards a combination of several technologies (bio-inspired and molecular imprinting techniques) and materials (cyclodextrins, surfactants, specific monomers). There is a tendency to develop systems which not only prolong the contact time of the vehicle at the ocular surface, but also at the same time slow down the clearance of the drug. Different materials can be applied during the development of contact lenses and can be combined with natural inspired strategies of drug immobilization and release, providing successful tools for ocular drug delivery systems.
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.
Sarac, Ozge; Gurdal, Canan; Bostancı-Ceran, Basak; Can, Izzet
The aim of this study was to evaluate tear osmolarity and ocular comfort with two different types of hydrogel daily disposable lenses. The right eyes of 15 first-time contact lens users were included in this prospective study. All eyes wore hilafilcon B silicone hydrogel contact lenses for 8 h (group 1). After 1 week without contact lenses, all eyes wore narafilcon A silicone hydrogel contact lenses for 8 h (group 2). Tear osmolarity measurement was performed before and after 4 and 8 h of each contact lens wear. Ocular comfort was assessed after 4 and 8 h of each contact lens wear. In group 1, the mean baseline, 4- and 8-h tear osmolarity values were 293 ± 10.57, 303.00 ± 10.5 mOsm/L (p = 0.023), and 295.0 ± 1.4 mOsm/L (p > 0.05), respectively. In group 2, the mean baseline, 4- and 8-h tear osmolarity values were 294 ± 13.65, 300.9 ± 11.3 mOsm/L (p = 0.007), and 298.80 ± 7.2 mOsm/L (p > 0.05), respectively. In group 1, the mean comfort score was 7.20 ± 0.45 and 8.60 ± 0.45 at 4 and 8 h, respectively (p = 0.038). In group 2, the mean comfort score significantly decreased from 9.80 ± 0.45 to 7.80 ± 0.84 at 4 h (p = 0.039). Both hydrogel and silicone hydrogel daily disposable contact lenses elevated tear osmolarity during 8 h of contact lens wear. The increase in tear osmolarity with both contact lenses was below the cut-off value for dry eye and was not associated with ocular comfort.
Szczotka-Flynn, Loretta; Lass, Jonathan H; Sethi, Ajay; Debanne, Sara; Benetz, Beth Ann; Albright, Matthew; Gillespie, Beth; Kuo, Jana; Jacobs, Michael R; Rimm, Alfred
This study determined which microbiologic, clinical, demographic, and behavioral factors are associated with corneal infiltrative events (CIEs) during continuous wear of silicone hydrogel (SH) contact lenses. Subjects (n = 205) were fitted with lotrafilcon A lenses for continuous wear and observed for 1 year. The main exposures of interest were corneal staining and bacterial lens contamination. Kaplan-Meier (KM) plots were used to estimate the cumulative unadjusted probability of remaining CIE free, and Cox proportional hazards regression was used to model the hazard of having a CIE, as a function of key predictor variables. The KM-unadjusted cumulative probability of remaining CIE free was 73.3%. Approximately 53% of subjects had repeated episodes of corneal staining (mild or greater), and 11.3% had repeated episodes of moderate or greater corneal staining. Corneal staining was not associated with the development of a CIE. The frequency of substantial bacterial bioburden on worn lenses at the time of a CIE was 64.7%, compared with only 12.2% during uncomplicated wear. The presence of substantial lens bacterial bioburden was associated with the development of a CIE (adjusted hazards ratio [HR], 8.66; 95% confidence interval [CI], 2.88-26.01). Smoking was also associated with a CIE (adjusted HR, 4.13; 95% CI, 1.27-13.45). Corneal staining is common during continuous wear of SH lenses, but it is not associated with the development of a CIE. Smoking and substantial lens bacterial bioburden pose prominent risks of a CIE. In this study, more than 70% of the total risk of CIE in those with substantial lens bioburden is attributable to this exposure. (ClinicalTrials.gov number, NCT00727402).
Szczotka-Flynn, Loretta B; Pearlman, Eric; Ghannoum, Mahmoud
A contact lens (CL) can act as a vector for microorganisms to adhere to and transfer to the ocular surface. Commensal microorganisms that uneventfully cohabitate on lid margins and conjunctivae and potential pathogens that are found transiently on the ocular surface can inoculate CLs in vivo. In the presence of reduced tissue resistance, these resident microorganisms or transient pathogens can invade and colonize the cornea or conjunctiva to produce inflammation or infection. The literature was reviewed and used to summarize the findings over the last 30 years on the identification, enumeration, and classification of microorganisms adherent to CLs and their accessories during the course of normal wear and to hypothesize the role that these microorganisms play in CL infection and inflammation. Lens handling greatly increases the incidence of lens contamination, and the ocular surface has a tremendous ability to destroy organisms. However, even when removed aseptically from the eye, more than half of lenses are found to harbor microorganisms, almost exclusively bacteria. Coagulase-negative Staphylococci are most commonly cultured from worn lenses; however, approximately 10% of lenses harbor Gram-negative and highly pathogenic species, even in asymptomatic subjects. In storage cases, the incidence of positive microbial bioburden is also typically greater than 50%. All types of care solutions can become contaminated, including up to 30% of preserved products. The process of CL-related microbial keratitis and inflammation is thought to be preceded by the presence or transfer or both of microorganisms from the lens to the ocular surface. Thus, this detailed understanding of lens-related bioburden is important in the understanding of factors associated with infectious and inflammatory complications. Promising mechanisms to prevent bacterial colonization on lenses and lens cases are forthcoming, which may decrease the incidence of microbially driven CL complications.
Lass, Jonathan H.; Sethi, Ajay; Debanne, Sara; Benetz, Beth Ann; Albright, Matthew; Gillespie, Beth; Kuo, Jana; Jacobs, Michael R.; Rimm, Alfred
Purpose. This study determined which microbiologic, clinical, demographic, and behavioral factors are associated with corneal infiltrative events (CIEs) during continuous wear of silicone hydrogel (SH) contact lenses. Methods. Subjects (n = 205) were fitted with lotrafilcon A lenses for continuous wear and observed for 1 year. The main exposures of interest were corneal staining and bacterial lens contamination. Kaplan-Meier (KM) plots were used to estimate the cumulative unadjusted probability of remaining CIE free, and Cox proportional hazards regression was used to model the hazard of having a CIE, as a function of key predictor variables. Results. The KM-unadjusted cumulative probability of remaining CIE free was 73.3%. Approximately 53% of subjects had repeated episodes of corneal staining (mild or greater), and 11.3% had repeated episodes of moderate or greater corneal staining. Corneal staining was not associated with the development of a CIE. The frequency of substantial bacterial bioburden on worn lenses at the time of a CIE was 64.7%, compared with only 12.2% during uncomplicated wear. The presence of substantial lens bacterial bioburden was associated with the development of a CIE (adjusted hazards ratio [HR], 8.66; 95% confidence interval [CI], 2.88–26.01). Smoking was also associated with a CIE (adjusted HR, 4.13; 95% CI, 1.27–13.45). Conclusions. Corneal staining is common during continuous wear of SH lenses, but it is not associated with the development of a CIE. Smoking and substantial lens bacterial bioburden pose prominent risks of a CIE. In this study, more than 70% of the total risk of CIE in those with substantial lens bioburden is attributable to this exposure. (ClinicalTrials.gov number, NCT00727402). PMID:20538985
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
Niu, Yafei; Sarver, Edwin J; Stevenson, Scott B; Marsack, Jason D; Parker, Katrina E; Applegate, Raymond A
To report the development of a tool designed to dynamically simulate the effect of soft toric contact lens movement on retinal image quality, initial findings on three eyes, and the next steps to be taken to improve the utility of the tool. Three eyes of two subjects wearing soft toric contact lenses were cyclopleged with 1% cyclopentolate and 2.5% phenylephrine. Four hundred wavefront aberration measurements over a 5-mm pupil were recorded during soft contact lens wear at 30 Hz using a complete ophthalmic analysis system aberrometer. Each wavefront error measurement was input into Visual Optics Laboratory (version 7.15, Sarver and Associates, Inc.) to generate a retinal simulation of a high contrast log MAR visual acuity chart. The individual simulations were combined into a single dynamic movie using a custom MatLab PsychToolbox program. Visual acuity was measured for each eye reading the movie with best cycloplegic spectacle correction through a 3-mm artificial pupil to minimize the influence of the eyes' uncorrected aberrations. Comparison of the simulated acuity was made to values recorded while the subject read unaberrated charts with contact lenses through a 5-mm artificial pupil. For one study eye, average acuity was the same as the natural contact lens viewing condition. For the other two study eyes visual acuity of the best simulation was more than one line worse than natural viewing conditions. Dynamic simulation of retinal image quality, although not yet perfect, is a promising technique for visually illustrating the optical effects on image quality because of the movements of alignment-sensitive corrections.
Guillon, Michel; Maïssa, Cécile
The objective of the investigation was to show that, because of their overall properties, Acuvue® Oasys™ with Hydraclear™ Plus brand (senofilcon A) silicone hydrogel contact lenses achieve excellent ocular tissue tolerance during long-term extended wear. The investigation was a 2-year, prospective, extended wear investigation of senofilcon A silicone hydrogel contact lenses worn for up to 6 nights without removal. The 2-year results compared with the subjects' baseline ocular statuses on entering the study revealed: The quantification of the effects on the ocular tissues of 2 years of extended wear of senofilcon A, by mainly previously successful daily soft contact lens wearers, found an excellent biocompatibility. The results support the hypothesis that senofilcon A contact lenses, when worn on a 6-night/7-day extended wear regimen, maintain excellent long-term ocular tissue tolerance. Copyright © 2010 American Optometric Association. Published by Elsevier Inc. All rights reserved.
Liu, Xiaowei; Wang, Peng; Kao, Andrew A; Jiang, Yang; Li, Ying; Long, Qin
To compare the locations and types of bacterial contamination of bandage disposable soft contact lenses after laser subepithelial keratectomy (LASEK) and photorefractive keratectomy (PRK). Bandage disposable soft contact lenses were collected with sterile forceps from 30 eyes of 15 consecutive patients treated with LASEK (LASEK group) and 30 eyes of 15 consecutive patients who underwent PRK (PRK group) to correct myopia. Immediately after collection, each lens was cut in two parts with sterile scissors and placed onto chocolate agar with one piece outer face down and the inner face down for the other piece. The lenses were analyzed for bacterial colonization and evaluated for the amount of growth on the inner face and outer face, respectively. The antibiotic susceptibility tests were performed for the isolates using disk diffusion. Five positive cultures (16.7%) were found in LASEK group: 4 appeared in the inner face of the lens and1 appeared in the outer face. In PRK group, 2 of the 30 contact lenses (6.67%) had positive cultures; both of them appeared in the outer face of the lens. The difference of positive culture rate in the two groups was not statistically significant (χ=1.46, P=0.228). When comparing the positive colonization rate in location, the positive culture rate in the inner face of LASEK group was statistically significantly higher than that of PRK group (13.3% vs. 0%, χ=4.29, P=0.038); however, no clinical finding of infection was noted. In both groups, methicillin-sensitive coagulase-negative staphylococci (MSSCoN) were the most common isolate. Besides MSSCoN, the growth of methicillin-resistant coagulase-negative staphylococci, Corynebacterium, and Micrococcus were also present in this study. All the microorganisms were sensitive to tobramycin, which was used in conjunction with dexamethasone to treat the cases. Previous literature reports that the risk of infectious keratitis after LASEK or PRK is relatively low. However, within this study, the
Sousa, Sidney Júlio de Faria E; Dias, Vanderson Glerian; Marcomini, Luís Antonio Gorla
This is the report of a case of bilateral Acanthamoeba keratitis in a 19-year-old woman who bought a pair of disposable soft contact lenses in a boutique. She wore this same pair of lenses for 3 months daily without the appropriate care. This led to bilateral corneal transplantation with cataract extraction and also trabeculectomy in the right eye. When last seen, both grafts were crystal clear but the visual acuities were far from satisfactory. She also had bilateral secondary glaucoma, barely controlled by topical medication. Actually, the physical features and the wearing time characteristics of the disposable soft contact lenses created unprecedented difficulties to the medical surveillance of their wearers. Without the right assistance they tend to become careless regarding routine cleaning. They also feel free to buy less expensive lenses, to use saline instead of lens solutions, to violate the limits of wearing time and to extend the use over the sleeping period. Additionally, the aggressive marketing and the wide distribution of these lenses increase the chances that economically or educationally unprepared people will acquire them. The question that remains is: Is the present case an accidental event or an example of what is likely to happen in the future if the indiscriminate selling of disposable soft contact lenses continues to evolve?
Khalil, M A; Sonbol, F I
The objective was to investigate the biofilm-forming capacity of methicillin resistant Staphylococcus aureus (MRSA) isolated from eye lenses of infected patients. A total of 32 MRSA isolated from contact lenses of patients with ocular infections were screened for their biofilm-forming capacity using tube method (TM), Congo red agar (CRA), and microtiter plate (MtP) methods. The effect of some stress factor on the biofilm formation was studied. The biofilm-forming related genes, icaA, icaD and 10 microbial surface components that recognize adhesive matrix molecule (MSCRAMM), of the selected MRSA were also detected using polymerase chain reaction. Of 32 MRSA isolates, 34.37%, 59.37%, and 81.25% showed positive results using CRA, TM or MtP, respectively. Biofilm production was found to be reduced in the presence of ethanol or ethylenediaminetetraacetic acid and at extreme pH values. On the other hand, glucose or heparin leads to a concentration dependent increase of biofilm production by the isolates. The selected biofilm producing MRSA isolate was found to harbor the icaA, icaD and up to nine of 10 tested MSCRAMM genes, whereas the selected non biofilm producing MRSA isolate did not carry any of the tested genes. The MtP method was found to be the most effective phenotypic screening method for detection of biofilm formation by MRSA. Furthermore, the molecular approach should be taken into consideration for the rapid and correct diagnosis of virulent bacteria associated with contact eye lenses.
Tarkowski, Witold; Moneta-Wielgoś, Joanna; Młocicki, Daniel
Demodex mites may be a potential etiological factor in the development of various eye and skin disorders. The aim of the study was to investigate the presence of Demodex in the hair follicles of eyelashes and their potential influence on abandoning soft contact lenses which had been previously well tolerated by their users. A group of 62 users of contact lenses (28 with emerging discomfort and 34 without discomfort) were examined. There is a need to check the existence of a relationship between D. folliculorum or/and D. brevis infestation and the emergence of intolerance to the presence of soft contact lenses. The removed lashes were examined under light microscopy, applying standard parasitological methods if demodicosis is suspected. A positive result was assumed if at least one adult stage, larva, protonymph/nymph, or egg of D. folliculorum and/or D. brevis was present. A positive correlation was observed between the presence of Demodex and intolerance to contact lenses by their existing users (p < 0.05), and Demodex sp. infections were observed in 92.86% of patients with intolerance to contact lenses. Our results provide further evidence for the pathogenic role played by the mites in the development of eye diseases. PMID:26290865
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.
Domínguez-Vicent, Alberto; Esteve-Taboada, Jose Juan; Recchioni, Alberto; Brautaset, Rune
To assess the power profile and in vitro optical quality of scleral contact lenses with different powers as a function of the optical aperture. The mini and semiscleral contact lenses (Procornea) were measured for five powers per design. The NIMO TR-1504 (Lambda-X) was used to assess the power profile and Zernike coefficients of each contact lens. Ten measurements per lens were taken at 3- and 6-mm apertures. Furthermore, the optical quality of each lens was described in Zernike coefficients, modulation transfer function, and point spread function (PSF). A convolution of each lens PSF with an eye-chart image was also computed. The optical power fluctuated less than 0.5 diopters (D) along the optical zone of each lens. However, the optical power obtained for some lenses did not match with its corresponding nominal one, the maximum difference being 0.5 D. In optical quality, small differences were obtained among all lenses within the same design. Although significant differences were obtained among lenses (P<0.05), these showed small impact in the image quality of each convolution. Insignificant power fluctuations were obtained along the optical zone measured for each scleral lens. Additionally, the optical quality of both lenses has showed to be independent of the lens power within the same aperture.
Tashakori-Sabzevar, Faezeh; Mohajeri, Seyed Ahmad
Recently, significant advances have been made in order to optimize drug delivery to ocular tissues. The main problems in ocular drug delivery are poor bioavailability and uncontrollable drug delivery of conventional ophthalmic preparations (e.g. eye drops). Hydrogels have been investigated since 1965 as new ocular drug delivery systems. Increase of hydrogel loading capacity, optimization of drug residence time on the ocular surface and biocompatibility with the eye tissue has been the main focus of previous studies. Molecular imprinting technology provided the opportunity to fulfill the above-mentioned objectives. Molecularly imprinted soft contact lenses (SCLs) have high potentials as novel drug delivery systems for the treatment of eye disorders. This technique is used for the preparation of polymers with specific binding sites for a template molecule. Previous studies indicated that molecular imprinting technology could be successfully applied for the preparation of SCLs as ocular drug delivery systems. Previous research, particularly in vivo studies, demonstrated that molecular imprinting is a versatile and effective method in optimizing the drug release behavior and enhancing the loading capacity of SCLs as new ocular drug delivery systems. This review highlights various potentials of molecularly imprinted contact lenses in enhancing the drug-loading capacity and controlling the drug release, compared to other ocular drug delivery systems. We have also studied the effects of contributing factors such as the type of comonomer, template/functional monomer molar ratio, crosslinker concentration in drug-loading capacity, and the release properties of molecularly imprinted hydrogels.
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
Zhu, Qiang; Liu, Chang; Sun, Zheng; Zhang, Xiaofei; Liang, Ning; Mao, Shirui
Contact lenses (CLs) are ideally suited for controlled ocular drug delivery, but are limited by short release duration, poor storage stability and low drug loading. In this study, we present a novel inner layer-embedded contact lens capable of pH-triggered extended ocular drug delivery with good storage stability. Blend film of ethyl cellulose and Eudragit S100 was used as the inner layer, while pHEMA hydrogel was used as outer layer to fabricate inner layer-embedded contact lens. Using diclofenac sodium(DS) as a drug model, influence of polymer ratio in the blend film, EC viscosity, drug/polymer ratio, inner layer thickness and outlayer thickness of pHEMA hydrogel on drug release behavior was studied and optimized for daily use. The pH-triggered drug eluting pattern enables the inner layer-embedded contact lens being stored in phosphate buffer solution pH 6.8 with ignorable drug loss and negligible changes in drug release pattern. In vivo pharmacokinetic study in rabbits showed sustained drug release for over 24 h in tear fluid, indicating significant improvement in drug corneal residence time. A level A IVIVC was established between in vitro drug release and in vivo drug concentration in tear fluid. In conclusion, this inner layer embedded contact lens design could be used as a platform for extended ocular drug delivery with translational potential for both anterior and posterior ocular diseases therapy. Copyright © 2018 Elsevier B.V. All rights reserved.
Dart, J K G; Radford, C F; Minassian, D; Verma, S; Stapleton, F
To assess the relative risks (RR) of microbial keratitis (MK) for contemporary contact lens (CL) types and wearing schedules. A 2-year prospective case-control study begun in December 2003. Cases were 367 CL wearers attending Moorfields Eye Hospital with proven or presumed MK. Controls were 1069 hospital controls, who were CL wearers with a disorder unrelated to CL wear, and 639 population-based controls who were CL wearers randomly selected from the Moorfields catchment area. Hospital patients completed a self-administered questionnaire; population-based controls were interviewed by telephone. Multivariate analysis was done both for all cases of MK, and for the moderate and severe MK subgroups alone. The RR for developing MK, and vision loss, for all lens types compared with planned replacement soft lenses (the referent). Compared with planned replacement soft lenses (the referent), the RR of MK was significantly increased with daily disposable (DD) CLs (RR, 1.56x [95% confidence interval (CI), 1.1-2.1]; P = 0.009) and differed between different brands of DD lens, was reduced for rigid lenses (RR, 0.16x [95% CI, 0.06-0.4]; P<0.001), and no different for silicone hydrogel or other types of soft lens. Although the risk of MK was higher overall among DD lens users, the risk of vision loss was less than for planned replacement soft CL users (P = 0.05); no DD lens users lost vision to the level of >or=20/40. The RR for overnight wear, for any lens type, was 5.4 times higher (95% CI, 3.3-10.9; P<0.001). Comparison of the DD soft CL types with planned replacement soft lenses (the referent), showed significant differences between brands for the risk of MK. The risk of MK has not been reduced in users of DD and silicone hydrogel CLs. However, vision loss is less likely to occur in DD than in reusable soft CL users. Different brands of CL may be associated with significantly different risks of keratitis; understanding these differences should lead to the development of
Vermeltfoort, Pit B J; Rustema-Abbing, Minie; de Vries, Joop; Bruinsma, Gerda M; Busscher, Henk J; van der Linden, Matthijs L; Hooymans, Johanna M M; van der Mei, Henny C
The aim of this study was to determine the effect of continuous wear on physicochemical surface properties of silicone hydrogel (S-H) lenses and their susceptibility to bacterial adhesion. In this study, volunteers wore 2 pairs of either "lotrafilcon A" or "balafilcon A" S-H contact lenses. The first pair was worn continuously for a week and the second pair for 4 weeks. One lens of each pair was used for surface characterization and the other one for bacterial adhesion experiments. Lens surfaces were characterized by examination of their wettability, roughness, elemental composition, and proteins attached to their surfaces. Adhesion of Staphylococcus aureus 835 and Pseudomonas aeruginosa #3 to a lens was studied using a parallel plate flow chamber. Before use, the lotrafilcon A lens was rougher than the balafilcon A lens and had a lower water contact angle and a higher affinity for S. aureus 835. After wear, both lens types had similar water contact angles, whereas the differences in elemental surface composition decreased as well. S. aureus 835 adhered in higher numbers to worn balafilcon A lenses, whereas the opposite was seen for P. aeruginosa #3. The initial deposition rates of both bacterial strains to lotrafilcon A lenses decreased by wearing and were found to correlate significant (P < 0.001) with the surface roughness of worn lenses. In this study, the differences in surface properties between 2 types of S-H lenses were found to change after 1 week of continuous wear. Generally, bacteria adhered in lower numbers and less tenaciously to worn lenses, except S. aureus 835, adhering in higher numbers to worn balafilcon A lenses.
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.
Gao, Shaohui; Wu, Junshu; Li, Lili; Wang, Yong; Zhong, Xingwu
To evaluate the efficacy of silicone hydrogel contact lenses on ocular surface after Sub-Bowman Keratomileusis (SBK). Forty-six patients suffered from myopia underwent a bilateral SBK. Post-operatively, one eye of each patient wore a PureVision contact lens for 24 h as a treated eye and the contralateral eye was as a blank control. Afterwards, corneal fluorescein (FL) staining, tear break-up time (TBUT), schirmer I test (SIT), central corneal thickness (CCT), ocular surface disease index (OSDI), corneal hysteresis (CH), corneal resistance factor (CRF) and corneal flap complications were assessed 1 d (except for CH and CRF), 1 week, 1 month and 3 months postoperatively. Following SBK, in contrast to the control, corneal fluorescein staining of treated eyes were significantly reduced and tear break-up time of treated eyes were significantly improved at 1 d and 1 week after SBK. However, Schirmer I test of treated and control eyes were not different after SBK. Central corneal thickness of treated eyes were significantly thinner than that of control at 1 d after SBK, however, there were no differences at other time points. Ocular surface disease index of treated eyes were obviously alleviated more than that of control at 1 d after SBK, but no differences were found at other visits. Moreover, Corneal hysteresis and corneal resistance factor of treated and un-treated eyes were not different after surgery. And also the rate of corneal flap complications were not different between treated and control eyes after SBK. Silicone hydrogel contact lenses played a positive role in accelerating corneal epithelial healing, enhancing tear film stability and reducing discomfort of patients in the early stage after SBK.
Hotta, Fumika; Imai, Shoji; Miyamoto, Tatsuro; Mitamura-Aizawa, Sayaka; Mitamura, Yoshinori
Objective: To investigate the surfaces and principal elements of the colorants of cosmetically tinted contact lenses (Cos-CLs). Methods: We analyzed the surfaces and principal elements of the colorants of five commercially available Cos-CLs using scanning electron microscopy with energy-dispersive x-ray analysis. Results: In two Cos-CLs, the anterior and posterior surfaces were smooth, and colorants were found inside the lens. One lens showed colorants located to a depth of 8 to 14 μm from the anterior side of the lens. In the other lens, colorants were found in the most superficial layer on the posterior surface, although a coated layer was observed. The colorants in the other three lenses were deposited on either lens surface. Although a print pattern was uniform in embedded type lenses, uneven patterns were apparent in dot-matrix design lenses. Colorants used in all lenses contained chlorine, iron, and titanium. In the magnified scanning electron microscopy images of a certain lens, chlorine is exuded and spread. Conclusions: Cosmetically tinted contact lenses have a wide variety of lens surfaces and colorants. Colorants may be deposited on the lens surface and consist of an element that has tissue toxicity. PMID:25799458
Ben Yaish, Shai; Zlotnik, Alex; Yehezkel, Oren; Lahav-Yacouel, Karen; Belkin, Michael; Zalevsky, Zeev
Purpose: Testing whether the extended depth of focus technology embedded on non-toric contact lenses is a suitable treatment for both astigmatism and presbyopia. Methods: The extended depth of focus pattern consisting of microndepth concentric grooves was engraved on a surface of a mono-focal soft contact lens. These grooves create an interference pattern extending the focus from a point to a length of about 1mm providing a 3.00D extension in the depth of focus. The extension in the depth of focus provides high quality focused imaging capabilities from near through intermediate and up to far ranges. Due to the angular symmetry of the engraved pattern the extension in the depth of focus can also resolve regular as well as irregular astigmatism aberrations. Results: The contact lens was tested on a group of 8 astigmatic and 13 subjects with presbyopia. Average correction of 0.70D for astigmatism and 1.50D for presbyopia was demonstrated. Conclusions: The extended depth of focus technology in a non-toric contact lens corrects simultaneously astigmatism and presbyopia. The proposed solution is based upon interference rather than diffraction effects and thus it is characterized by high energetic efficiency to the retina plane as well as reduced chromatic aberrations.
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.
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.
Lara Oya, Ana; Medialdea Hurtado, María Eloisa; Rojo Martín, María Dolores; Aguilera Pérez, Antonia; Alastruey-Izquierdo, Ana; Miranda Casas, Consuelo; Rubio Prats, Marina; Medialdea Marcos, Santiago; Navarro Marí, José María
Fungal keratitis is a severe ocular infection that primarily affects subjects engaged in outdoor activities. Risk factors include allergic conjunctivitis, previous eye surgery, previous treatment with wide-spectrum antimicrobial agents and corticosteroids and using contact lenses. Corneal infection is usually secondary to trauma involving organic material, which is often the only predisposing factor. Early diagnosis based on clinical examination and microbiological investigation (microscopy, cultures and molecular techniques) is crucial to selecting the appropriate antifungal therapy and prevent progression. We report the case of a patient with keratitis due to Beauveria bassiana, an opportunistic and entomopathogenic filamentous fungus that is used as a biological insecticide and which is a rare cause of corneal infection. We review previous cases reports of B. bassiana keratitis published and its main features to compare with our case, a female occasional agriculture worker who had not suffered any trauma involving organic material. The patient received topical and oral antifungal therapy and debridement surgery, with a satisfactory outcome.
Mukherjee, Achyut; Ioannides, Antonis; Aslanides, Ioannis
Purpose To evaluate and compare Comfilcon A and Senofilcon A silicone hydrogel contact lenses used as a therapeutic bandage following transepithelial excimer laser photorefractive keratectomy (PRK). Methods Patients undergoing transepithelial PRK for myopia were prospectively recruited. Included patients had a Comfilcon A silicone hydrogel lens inserted in one eye, with a Senofilcon A lens in the contralateral eye. Postoperative assessment of subjective pain, epithelial healing and visual recovery was at day 1, 3 and 7. Contact lens factors including centration, movement and deposits were assessed. Results 48 eyes of 24 patients were included in the study. Mean age was 31 years (SD 11) and mean refractive error −4.5 D (SD 1.8). Mean pain score at day 1 was significantly higher in the Comfilcon group at 4.6 (SD 2.7) vs. 1.5 (SD2.5) in the Senofilcon group (P < 0.005). Mean time to healing was 3.17 days (SD 0.37) in the Comfilcon group, and 3.21 days (SD 0.4) in the Senofilcon group, with no difference in defect size. There was a pronounced central raphe in 1 eye in the Comfilcon group vs. 5 eyes in the Senofilcon group (P = 0.19). Significantly more eyes demonstrated no lens movement in the Senofilcon group (18 vs. 4, P = 0.0001). Conclusion The variation in material characteristics and lens geometry of different silicone hydrogel lenses affects their clinical characteristics in therapeutic roles. Other factors than oxygen permeability may affect pain and epithelial healing, with superior pain relief from the less permeable Senofilcon lens in this study. PMID:25649638
Mukherjee, Achyut; Ioannides, Antonis; Aslanides, Ioannis
To evaluate and compare Comfilcon A and Senofilcon A silicone hydrogel contact lenses used as a therapeutic bandage following transepithelial excimer laser photorefractive keratectomy (PRK). Patients undergoing transepithelial PRK for myopia were prospectively recruited. Included patients had a Comfilcon A silicone hydrogel lens inserted in one eye, with a Senofilcon A lens in the contralateral eye. Postoperative assessment of subjective pain, epithelial healing and visual recovery was at day 1, 3 and 7. Contact lens factors including centration, movement and deposits were assessed. 48 eyes of 24 patients were included in the study. Mean age was 31 years (SD 11) and mean refractive error -4.5 D (SD 1.8). Mean pain score at day 1 was significantly higher in the Comfilcon group at 4.6 (SD 2.7) vs. 1.5 (SD2.5) in the Senofilcon group (P<0.005). Mean time to healing was 3.17 days (SD 0.37) in the Comfilcon group, and 3.21 days (SD 0.4) in the Senofilcon group, with no difference in defect size. There was a pronounced central raphe in 1 eye in the Comfilcon group vs. 5 eyes in the Senofilcon group (P=0.19). Significantly more eyes demonstrated no lens movement in the Senofilcon group (18 vs. 4, P=0.0001). The variation in material characteristics and lens geometry of different silicone hydrogel lenses affects their clinical characteristics in therapeutic roles. Other factors than oxygen permeability may affect pain and epithelial healing, with superior pain relief from the less permeable Senofilcon lens in this study. Copyright © 2013 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.
Qu, Wenwen; Busscher, Henk J; van der Mei, Henny C; Hooymans, Johanna M M
To measure adhesion forces of Pseudomonas aeruginosa, Staphylococcus aureus, and Serratia marcescens to a rigid contact lens (CL), standard polypropylene, and Ag-impregnated lens cases using atomic force microscopy and determine bacterial transmission from lens case to CL. Adhesion forces of bacterial strains to Ag-impregnated and polypropylene lens cases and a rigid CL were measured using atomic force microscopy. Adhesion forces were used to calculate Weibull distributions, from which transmission probabilities from lens case to CL were derived. Transmission probabilities were compared with actual transmission of viable bacteria from a lens case to the CL in 0.9% NaCl and in an antimicrobial lens care solution. Bacterial transmission probabilities from polypropylene lens cases based on force analysis coincided well for all strains with actual transmission in 0.9% NaCl. Bacterial adhesion forces on Ag-impregnated lens cases were much smaller than that on polypropylene and CLs, yielding a high probability of transmission. Comparison with actual bacterial transmission indicated bacterial killing due to Ag ions during colony-forming unit transmission from an Ag-impregnated lens case, especially for P. aeruginosa. Transmission of viable bacteria from Ag-impregnated lens cases could be further decreased by use of an antimicrobial lens care solution instead of 0.9% NaCl. Bacterial transmission probabilities are higher from Ag-impregnated lens cases than from polypropylene lens cases because of small adhesion forces, but this is compensated for by enhanced bacterial killing due to Ag impregnation, especially when in combination with an antimicrobial lens care solution. This calls for a balanced combination of antimicrobial lens care solutions and surface properties of a lens case and CL.
Varikooty, Jalaiah; Keir, Nancy; Woods, Craig A; Fonn, Desmond
To determine whether the refractive index (RI) of a soft contact lens can be evaluated using refractometry while the lens remains on the eye and to compare this with more traditional ex vivo RI measurements. A slitlamp apparatus was modified to incorporate a customized Atago hand refractometer. With a double-masked study design, nine adapted symptomatic soft contact lens wearers wore a contact lens in each eye (lotrafilcon B and etafilcon A) in a randomized order. In vivo RI was determined from the relative Brix scale measurements immediately after lens insertion and after 1 and 10 hr of lens wear. Ex vivo refractometry was performed after 10 hr of lens wear for comparison. Means +/- standard errors of the means are reported. In vivo RI values at baseline were 1.422 +/- 0.0004 (lotrafilcon B) and 1.405 +/- 0.0021 (etafilcon A); after 1 hr of lens wear, values were 1.423 +/- 0.0006 and 1.408 +/- 0.0007, respectively; and after 10 hr of lens wear, values were 1.424 +/- 0.0004 and 1.411 +/- 0.0010, respectively. Ex vivo RI values at the end of the 10 hr wearing period were 1.424 +/- 0.0003 (lotrafilcon B) and 1.412 +/- 0.0017 (etafilcon A). The change in in vivo RI across the day was statistically significant for the etafilcon A lens (repeated-measures analysis of variance, P<0.01) but not for the lotrafilcon B lens (P>0.05). This novel adaptation of refractometry was able to measure the RI of soft contact lenses during wear (without lens removal). End of day RI measurements using in vivo and ex vivo refractometry were comparable with each other. Future work is required to determine whether this in vivo method can improve our understanding of the relationships between soft contact lens RI, hydration, on-eye lens performance, and symptomology.
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.
Santos, Lívia; Rodrigues, Diana; Lira, Madalena; Oliveira, M Elisabete C D Real; Oliveira, Rosário; Vilar, Eva Yebra-Pimentel; Azeredo, Joana
To evaluate the influence of surface treatment of silicone-hydrogel CL on lens hydrophobicity, protein adsorption and microbial colonisation by studying several silicone hydrogel contact lenses (CL) with and without surface treatment. The lenses used in this study were Balafilcon A, Lotrafilcon A, Lotrafilcon B and Galyfilcon A. A conventional hydrogel CL (Etafilcon A) was also tested. Hydrophobicity was determined through contact angle measurement using the advancing type technique on air. The type and quantity of proteins adsorbed were assessed through SDS-PAGE and fluorescence spectroscopy, respectively. Microbial colonisation was studied by removing the microbes from the lenses through sonication, and counting the colony-forming units on agar plates. Regarding hydrophobicity, both surface and non-surface-treated silicone hydrogel CL were found to be hydrophobic, and the conventional hydrogel CL was found to be hydrophilic. Concerning protein adsorption, different protein profiles were observed on the several lenses tested. Nevertheless, the presence of proteins with the same molecular weight as lysozyme and lactoferrin was common to all lenses, which is probably related to their abundance in tears. In terms of total protein adsorption, silicone hydrogel CL did not exhibit any differences between themselves. However, the conventional hydrogel Etafilcon A adsorbed a larger amount of proteins. Regarding microbial colonisation, Balafilcon A exhibited the greatest amount of colonising microbes, which can be due to its superior hydrophobicity and higher electron acceptor capacity. This study suggests that silicone hydrogel lenses adsorb a lower amount of proteins than the conventional hydrogel lenses and that this phenomenon is independent of the presence of surface treatment. Concerning microbial colonisation, the surface treated Balafilcon A, exhibited a greater propensity, a fact that may compromise the lens wearer's ocular health.
Triharpini, Ni Nyoman; Gede Jayanegara, I Wayan; Handayani, Ariesanti Tri; Widiana, I Gde Raka
Corneal erosion is common in eye emergency cases. Extensive corneal erosions result in severe pain and prolonged healing time. This study aimed to compare bandage contact lenses with pressure patching in terms of reducing the size of the erosion area, pain scale in patients with corneal erosion and its complications. A randomized open-label clinical trial was conducted. Subjects with mechanical corneal erosion were selected to use either bandage contact lenses or pressure patching. All subjects received antibiotic eye drops and 0.5% tropicamide eye drops. Evaluations were done 24 and 72 hours after treatment. The size of the corneal erosion area, pain scale, and complications were assessed. A total of 32 eyes (16 eyes in each group) were studied. The change in the size of the corneal erosion area was greater in the bandage contact lens group than in the pressure patching group, although there was no significant difference. In the bandage contact lens group, 56.25% of the eyes were healed at 24 hours and 43.75% were healed at 72 hours. In the pressure patching group, 62.50% were healed at 24 hours and 12.50% were healed at 72 hours. The change in pain scale was significantly greater in the bandage contact lens group than in the pressure patching group. No complications were found in both groups. Bandage contact lenses are an effective alternative to treating mechanical corneal erosion because of their effect in reducing pain without causing any complications.
Sankaridurg, Padmaja R.; Sharma, Savitri; Willcox, Mark; Naduvilath, Thomas J.; Sweeney, Deborah F.; Holden, Brien A.; Rao, Gullapalli N.
Microorganisms, especially gram-negative bacteria, are considered to play a role in the etiology of certain corneal infiltrative events (CIEs) observed during soft contact lens wear. This study explored the possibility of microbial colonization of soft contact lenses as a risk factor leading to CIEs. In a clinical trial conducted from March 1993 to January 1996, 330 subjects wore disposable soft contact lenses on a 6-night extended-wear and disposal schedule. During this period, 4,321 lenses (118 during CIEs; 4,203 during asymptomatic lens wear) were recovered aseptically and analyzed for microbial colonization. A greater percentage of lenses were free from microbial colonization during asymptomatic wear than during CIEs (42 versus 23%; P < 0.0001). The incidence of gram-positive bacteria, gram-negative bacteria and fungi was greater during CIEs than during asymptomatic lens wear (P < 0.05). During asymptomatic lens wear, gram-positive bacteria were isolated most frequently and were usually normal external ocular microbiota. Of the gram-positive bacteria, the incidence of Streptococcus pneumoniae was greater during CIE than during asymptomatic wear (7.6 versus 0.6%; P < 0.0001). While gram-negative bacteria were seen in few cases during asymptomatic wear, their incidence during CIE in comparison to asymptomatic wear was substantial and significant (23.7 versus 3.8%; P < 0.0001). Also, the level of colonization was high. Of CIEs, events of microbial keratitis, contact lens acute red eye, and asymptomatic infiltrative keratitis were associated with lens colonization with gram-negative bacteria or S. pneumoniae. Colonization of soft contact lenses with pathogenic bacteria, especially gram-negative bacteria and S. pneumoniae, appears to be a significant risk factor leading to CIE. PMID:11101574
Bakaraju, Ravi C; Ehrmann, Klaus; Falk, Darrin; Ho, Arthur; Papas, Eric
A physical model eye capable of carrying soft contact lenses (CLs) was used as a platform to evaluate optical performance of several commercial multifocals (MFCLs) with high- and low-add powers and a single-vision control. Optical performance was evaluated at three pupil sizes, six target vergences, and five CL-correcting positions using a spatially filtered monochromatic (632.8 nm) light source. The various target vergences were achieved by using negative trial lenses. A photosensor in the retinal plane recorded the image point-spread that enabled the computation of visual Strehl ratios. The centration of CLs was monitored by an additional integrated en face camera. Hydration of the correcting lens was maintained using a humidity chamber and repeated instillations of rewetting saline drops. All the MFCLs reduced performance for distance but considerably improved performance along the range of distance to near target vergences, relative to the single-vision CL. Performance was dependent on add power, design, pupil, and centration of the correcting CLs. Proclear (D) design produced good performance for intermediate vision, whereas Proclear (N) design performed well at near vision (p < 0.05). AirOptix design exhibited good performance for distance and intermediate vision. PureVision design showed improved performance across the test vergences, but only for pupils ≥4 mm in diameter. Performance of Acuvue bifocal was comparable with other MFCLs, but only for pupils >4 mm in diameter. Acuvue Oasys bifocal produced performance comparable with single-vision CL for most vergences. Direct measurement of single-pass images at the retinal plane of a physical model eye used in conjunction with various MFCLs is demonstrated. This method may have utility in evaluating the relative effectiveness of commercial and prototype designs.
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.
Cerviño, Alejandro; Gonzalez-Meijome, Jose M; Linhares, João M M; Hosking, Sarah L; Montes-Mico, Robert
To investigate the effect of two tinted contact lenses (CL) designed for outdoor sports activity on the psychometric determination of retinal straylight using the compensation comparison method. Thirteen emmetropic subjects were randomly fitted with two different tinted Nike Maxsight (Bausch & Lomb, Rochester, NY, USA) CL in one eye, while the contralateral eye was fitted with a clear lens made of the same material (Optima 38, Bausch & Lomb). Three valid straylight measurements were taken on each eye before and a few minutes after lens insertion, when lens stabilization had occurred. The subjects' mean straylight values were 0.90 +/- 0.09 at baseline and 0.95 +/- 0.10 with the clear Optima 38 CL. Straylight values were 0.97 +/- 0.10 and 1.0 +/- 0.10 log units with the amber and grey-green tinted CL, respectively. Differences in straylight between baseline (without CL) and with the clear CL in place were neither statistically significant (p = 0.066) nor was there a significant difference between baseline and the amber CL (p = 0.052). However, the grey-green CL showed a statistically significant difference from baseline (p = 0.006). Differences in straylight with the clear CL compared with the grey-green CL were also statistically different from zero (p = 0.002) showing an increased straylight value for the tinted CL. These differences were variable, but consistent for each subject, thus those showing higher or lower changes with one tinted lens tended to show the same trend with the second lens (r(2) = 0.736). Despite increases having been found in straylight values with tinted contact lenses, those changes are not likely to induce clinically significant changes in visual function under photopic conditions, even for the grey-green CL, which seems to increase straylight values more significantly than the amber CL. This difference between the tinted CL could suggest a wavelength dependence of straylight values, although this should be investigated further by
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
Guillon, Michel; Maïssa, Cécile
The objective of the investigation was to show that, because of their overall properties, Acuvue® Oasys™ with Hydraclear® Plus brand (senofilcon A) silicone hydrogel contact lenses achieve excellent ocular tissue tolerance during long-term daily wear. The 2-year investigation was a prospective daily wear analysis of Acuvue® Oasys™ with Hydraclear® Plus (senofilcon A) silicone hydrogel contact lenses replaced every 2 weeks and used in conjunction with a representative range of care systems. The 2-year results compared with the subjects' baseline ocular status on entering the study revealed: The quantification of the effects on the ocular tissues of 2 years of daily wear of senofilcon A, by mainly previously successful daily soft contact lens wearers, showed an excellent biocompatibility. The results support the hypothesis that senofilcon A contact lenses, when worn on a 2-week daily wear regimen, maintain excellent long-term ocular tissue tolerance. Copyright © 2010 American Optometric Association. Published by Elsevier Inc. All rights reserved.
To assess the possibility of estimating the refractive index of rigid contact lenses on the basis of measurements of their back vertex power (BVP) in air and when immersed in liquid. First, a spreadsheet model was used to quantify the magnitude of errors arising from simulated inaccuracies in the variables required to calculate refractive index. Then, refractive index was calculated from in-air and in-liquid measurements of BVP of 21 lenses that had been made in three negative BVPs from materials with seven different nominal refractive index values. The power measurements were made by two operators on two occasions. Intraobserver reliability showed a mean difference of 0.0033±0.0061 (t = 0.544, P = 0.59), interobserver reliability showed a mean difference of 0.0043±0.0061 (t = 0.707, P = 0.48), and the mean difference between the nominal and calculated refractive index values was -0.0010±0.0111 (t = -0.093, P = 0.93). The spreadsheet prediction that low-powered lenses might be subject to greater errors in the calculated values of refractive index was substantiated by the experimental results. This method shows good intra and interobserver reliabilities and can be used easily in a clinical setting to provide an estimate of the refractive index of rigid contact lenses having a BVP of 3 D or more.
Coiffard, L; Rivalland, P; De Roeck-Holtzhauer, Y
We characterized some market products designed for cleaning contact lenses and we compared their properties to the main requirements of eye-washes. We performed several physicochemical controls including pH determination, viscosity with a Baume apparatus and the decreasing of the freezing point following the method described by the French Pharmacopea. In addition, we carried out certain analytical controls, concerning three active principles (thiomersal, chlorhexidin digluconate, hydrogen peroxide), at the opening of the different package and after accelerated aging. A microbiological control was performed when opening the product and after a simulation of a 5-day aging. We finally determined the efficacy of the products on four bacterial strains for tests and of deproteinizing products on artificial dust. The pH values obtained ranged from 4.0 (oxygenated water solutions) to 7.8. The viscosity was close to a water solution one. Contents in active substances were usually similar to those stated on the package. At opening, the bacteriological quality was excellent. But, the multidose package were highly contaminated when used. Finally decontaminating efficacy against some germs was very good for the products tested. The results obtained show that the rincing products best answer the eye-wash criteria taken as references. Their main disadvantage is their contamination in the case of multidose packaging.
Madrid-Costa, David; Ruiz-Alcocer, Javier; García-Lázaro, Santiago; Albarrán-Diego, César; Ferrer-Blasco, Teresa
The aim of this study was to evaluate whether the creation of 2 foci (distance and near) provided by multizone refractive multifocal contact lenses (CLs) for presbyopia correction affects the measurements on Humphreys 24-2 Swedish interactive threshold algorithm (SITA) standard automated perimetry (SAP). In this crossover study, 30 subjects were fitted in random order with either a multifocal CL or a monofocal CL. After 1 month, a Humphrey 24-2 SITA standard strategy was performed. The visual field global indices (the mean deviation [MD] and pattern standard deviation [PSD]), reliability indices, test duration, and number of depressed points deviating at P<5%, P<2%, P<1%, and P<0.5% on pattern deviation probability plots were determined and compared between multifocal and monofocal CLs. Thirty eyes of 30 subjects were included in this study. There were no statistically significant differences in reliability indices or test duration. There was a statistically significant reduction in the MD with the multifocal CL compared with monfocal CL (P=0.001). Differences were not found in PSD nor in the number of depressed points deviating at P<5%, P<2%, P<1%, and P<0.5% in the pattern deviation probability maps studied. The results of this study suggest that the multizone refractive lens produces a generalized depression in threshold sensitivity as measured by the Humphreys 24-2 SITA SAP.
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.
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.
Santos, Lívia; Rodrigues, Diana; Lira, Madalena; Oliveira, Rosario; Real Oliveira, M Elisabete C D; Vilar, Eva Yebra-Pimentel; Azeredo, Joana
In this study, the effect of the natural surfactants octylglucoside and sodium cholate in inhibiting Staphylococcus epidermidis and Pseudomonas aeruginosa adhesion to conventional and silicone-hydrogel contact lenses (CL) was assessed. Hydrophobicity was also evaluated to conditioned and nonconditioned CL. The inhibiting effect of the tested surfactants was determined through "in vitro" adhesion studies to conditioned and nonconditioned CL followed by image acquisition and cell enumeration. Hydrophobicity was evaluated through contact angle measurements using the advancing type technique on air. Sodium cholate exhibits a very low capability to inhibit microbial adhesion. Conversely, octylglucoside effectively inhibited microbial adhesion in both types of lenses. This surfactant exhibited an even greater performance than a multipurpose lens care solution used as control. Octylglucoside was the only tested surfactant able to lower the hydrophobicity of all CL, which can explain its high performance. The results obtained in this study point out the potential of octylglucoside as a conditioning agent to prevent microbial colonization.
Chahal, Harinder S; Estrada, Marcela; Sindt, Christine W; Boehme, Jacob A; Greiner, Mark A; Nerad, Jeffrey A; Carter, Keith D; Allen, Richard C; Shriver, Erin M
To describe the role and efficacy of scleral contact lenses (SCLs) in the treatment of progressive keratopathy in patients who have undergone periocular surgical procedures, to investigate the financial impact of these surgical interventions, and to demonstrate the role of oculoplastic surgery in improving scleral contact lens fit. A retrospective medical record review was performed to identify patients who both received SCLs and were examined by the oculoplastics service at the University of Iowa between January 1990 and December 2015. Inclusion criteria also required a minimum of 12 months of patient follow up after being fit with a SCL. The indication for SCL use, as well as clinical outcomes and cumulative relative value units (RVUs) of prior oculoplastic treatments and SCL therapy were recorded for each patient. Six hundred and fifty-nine patients were fitted with SCLs at the authors' institution during the 25-year study period, 43 of whom were examined by the oculoplastics service for reasons related to their SCL. Patients who were fitted for SCLs before (27 patients) or after (16 patients) evaluation in the oculoplastics clinic presented with a variety of corneal and periocular pathology. Corneal indications for SCLs in patients seen secondarily in the oculoplastics clinic included decreased corneal sensation (from CN V palsy or neurotrophic keratopathy), decreased corneal healing from limbal stem cell deficiency, exposure keratopathy, and keratoconjunctivitis sicca secondary to Sjogren's syndrome or orbital radiation. Indications for oculoplastic clinic evaluation in current scleral lens patients included lagophthalmos, trichiasis, epiphora, cicatricial changes in the eyelids or fornices, and eyelid or eyebrow malposition affecting SCL centration. In all 27 patients, surgical intervention resulted in improved SCL centration. Sixteen patients (5 with CN VII palsy, 4 with CN V and CN VII palsy, 4 with neurotrophic keratitis, and 3 with cicatricial entropion
Ortillés, Ángel; Goñi, Pilar; Rubio, Encarnación; Sierra, Marta; Gámez, Ekaterina; Fernández, María T; Benito, María; Cristóbal, José Á; Calvo, Begoña
To develop a rabbit model of Acanthamoeba keratitis (AK) as the best method to reproduce the natural course of this disease. To induce AK, infected contact lenses (1000 amoebae/mm2, 90% trophozoites) were placed over the previously debrided corneal surface, in combination with a temporary tarsorrhaphy. Environmental and clinical strains of Acanthamoeba spp. (genotype T4) were used. Three groups (1L, n = 32; 2L-21d, n = 5; 2L-3d, n = 23) were established according to the number of contact lenses used (1L, 1 lens; 2L-21d and 2L-3d, 2 lenses) and the placement day of these (1L, day 1; 2L-21d, days 1 and 21; 2L-3d, days 1 and 3). The infection was quantified by a clinical score system and confirmed using corneal cytology and culture, polymerase chain reaction and histopathologic analysis. The infection rate obtained was high (1L, 87.5%; 2L-21d, 100%; 2L-3d, 82.6%), although no clinical signs were observed in the 50% of the infected animals in group 1L. Among groups, group 2L-3d showed more cases of moderate and severe infection. Among strains, no statistically significant differences were found in the infection rate. In the control eyes, cross infection was confirmed when a sterile contact lens was placed in the previously debrided corneas but not if the eye remained intact. The combination of two infected contact lenses after corneal debridement seems to be an alternative model, clinically and histopathologically similar to its human counterpart, to induce the different AK stages and reproduce the course of the disease in rabbits.
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.
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.
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
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
Veli, Muhammed; Ozcan, Aydogan
We present a cost-effective and portable platform based on contact lenses for noninvasively detecting Staphylococcus aureus, which is part of the human ocular microbiome and resides on the cornea and conjunctiva. Using S. aureus-specific antibodies and a surface chemistry protocol that is compatible with human tears, contact lenses are designed to specifically capture S. aureus. After the bacteria capture on the lens and right before its imaging, the captured bacteria are tagged with surface-functionalized polystyrene microparticles. These microbeads provide sufficient signal-to-noise ratio for the quantification of the captured bacteria on the contact lens, without any fluorescent labels, by 3D imaging of the curved surface of each lens using only one hologram taken with a lens-free on-chip microscope. After the 3D surface of the contact lens is computationally reconstructed using rotational field transformations and holographic digital focusing, a machine learning algorithm is employed to automatically count the number of beads on the lens surface, revealing the count of the captured bacteria. To demonstrate its proof-of-concept, we created a field-portable and cost-effective holographic microscope, which weighs 77 g, controlled by a laptop. Using daily contact lenses that are spiked with bacteria, we demonstrated that this computational sensing platform provides a detection limit of ∼16 bacteria/μL. This contact-lens-based wearable sensor can be broadly applicable to detect various bacteria, viruses, and analytes in tears using a cost-effective and portable computational imager that might be used even at home by consumers.
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.
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 antibiotics prophylaxis. Patients completed standardized symptom questionnaires at enrollment and at 2 weeks, 4 weeks and 3 months afterwards. Ophthalmologic assessment was performed at enrollment, at 2 weeks and afterwards 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=0.01), to 61.8 at 4 weeks (p=0.005) and to 56.3 at 3 months (p=0.02). 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 (58%) at 4 weeks and in 9 (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 graft-versus host disease in approximately 50% of patients. This study was registered at www.clinicaltrials.gov as NCT01616056. PMID:26189353
Hirasawa, Kazunori; Ito, Hikaru; Ohori, Yukari; Takano, Yui; Shoji, Nobuyuki
AIM To evaluate the refractive correction for standard automated perimetry (SAP) in eyes with refractive multifocal contact lenses (CL) in healthy young participants. METHODS Twenty-nine eyes of 29 participants were included. Accommodation was paralyzed in all participants with 1% cyclopentolate hydrochloride. SAP was performed using the Humphrey SITA-standard 24-2 and 10-2 protocol under three refractive conditions: monofocal CL corrected for near distance (baseline); multifocal CL corrected for distance (mCL-D); and mCL-D corrected for near vision using a spectacle lens (mCL-N). Primary outcome measures were the foveal threshold, mean deviation (MD), and pattern standard deviation (PSD). RESULTS The foveal threshold of mCL-N with both the 24-2 and 10-2 protocols significantly decreased by 2.2-2.5 dB (P<0.001), while that of mCL-D with the 24-2 protocol significantly decreased by 1.5 dB (P=0.0427), as compared with that of baseline. Although there was no significant difference between the MD of baseline and mCL-D with the 24-2 and 10-2 protocols, the MD of mCL-N was significantly decreased by 1.0-1.3 dB (P<0.001) as compared with that of both baseline and mCL-D, with both 24-2 and 10-2 protocols. There was no significant difference in the PSD among the three refractive conditions with both the 24-2 and 10-2 protocols. CONCLUSION Despite the induced mydriasis and the optical design of the multifocal lens used in this study, our results indicated that, when the dome-shaped visual field test is performed with eyes with large pupils and wearing refractive multifocal CLs, distance correction without additional near correction is to be recommended. PMID:29062776
Hirasawa, Kazunori; Ito, Hikaru; Ohori, Yukari; Takano, Yui; Shoji, Nobuyuki
To evaluate the refractive correction for standard automated perimetry (SAP) in eyes with refractive multifocal contact lenses (CL) in healthy young participants. Twenty-nine eyes of 29 participants were included. Accommodation was paralyzed in all participants with 1% cyclopentolate hydrochloride. SAP was performed using the Humphrey SITA-standard 24-2 and 10-2 protocol under three refractive conditions: monofocal CL corrected for near distance (baseline); multifocal CL corrected for distance (mCL-D); and mCL-D corrected for near vision using a spectacle lens (mCL-N). Primary outcome measures were the foveal threshold, mean deviation (MD), and pattern standard deviation (PSD). The foveal threshold of mCL-N with both the 24-2 and 10-2 protocols significantly decreased by 2.2-2.5 dB ( P <0.001), while that of mCL-D with the 24-2 protocol significantly decreased by 1.5 dB ( P =0.0427), as compared with that of baseline. Although there was no significant difference between the MD of baseline and mCL-D with the 24-2 and 10-2 protocols, the MD of mCL-N was significantly decreased by 1.0-1.3 dB ( P <0.001) as compared with that of both baseline and mCL-D, with both 24-2 and 10-2 protocols. There was no significant difference in the PSD among the three refractive conditions with both the 24-2 and 10-2 protocols. Despite the induced mydriasis and the optical design of the multifocal lens used in this study, our results indicated that, when the dome-shaped visual field test is performed with eyes with large pupils and wearing refractive multifocal CLs, distance correction without additional near correction is to be recommended.
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.
Leube, Alexander; Kovats, Imre; Wahl, Siegfried; Sickenberger, Wolfgang
Pilot study to investigate the feasibility of an axis-free correction approach of regular astigmatism using soft, bifocal contact lenses (CL). The investigation covers an optical simulation and a pilot study for the assessment of visual performance (over refraction OR, monocular visual acuity VA). The power of the two zones was adjusted according to the power of the astigmatic meridians, individually. Subjective performance was assessed in 30 participants with a mean horizontal cylindrical component of J 0 =- 0.65±1.29 D (cylinder from -0.75 to -4.00 DC). OR and VA were measured directly after fitting the CL, after one hour and after 5days (3FUP). Evaluating the modulation transfer function, CL increased the Strehl ratio by 10% and the transferred spatial frequency was improved from 6.6 cpd to 21.3 cpd. Analysis of Sturm's interval revealed a residual astigmatism of D Ast =0.73 D. OR revealed a statistically significant reduction of spherical error between baseline and all follow up (ΔM=-2.14 D, p<0.001) and between the J 0 from baseline to 3FUP (ΔJ 0 =-0.46 D, p=0.04). Wearing the CL for 5days did not result in a significant difference of VA (ΔVA 3FUP =+0.01 logMAR, p=0.99). Axis-free correction of astigmatism using bifocal CL resulted in reasonable performance based on computer simulation. Participants showed no clinically reduced visual acuity or contrast sensitivity. Further clinical studies are needed to show if this approach provides a good alternative to conventional astigmatic correction. Copyright © 2017 The Authors. Published by Elsevier Ltd.. 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.
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.
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.
Ruiz-Alcocer, Javier; Madrid-Costa, David; Radhakrishnan, Hema; Ferrer-Blasco, Teresa; Montés-Micó, Robert
The aim of this study was to evaluate ocular aberration changes through different simultaneous vision multifocal contact lenses (CLs). Eighteen young-adult subjects with a mean age of 29.8±2.11 years took part. Changes in accommodative response, spherical aberration (C(4)(0)), horizontal coma (C(3)(1)), vertical coma (C(3)(-1)), and root mean square (RMS) of higher-order aberrations (HOAs, third to sixth orders) were evaluated. Measurements were obtained with a distance-single vision CL and 2 aspheric multifocal CLs of simultaneous focus center-near design (PureVision Low Add and PureVision High Add) for 2 accommodative stimuli (-2.50 and -4.00 D). All measurements were performed monocularly with a Hartmann-Shack aberrometer (IRX-3; Imagine Eyes, Orsay, France). No statistically significant differences were found in accommodative responses to -2.50- and -4.00-D stimuli between the single vision CL and the 2 multifocal CLs. Spherical aberration was found to decrease and become more negative with accommodation for both stimuli with all three CLs. Horizontal coma decreased significantly with accommodation (-2.5- and -4.00-D stimuli) for the distance-single vision CLs (P=0.002 and P=0.003). No differences were found in vertical coma Zernike coefficients. The RMS of HOAs was found to decrease only with the single vision CLs for both stimuli (P<0.01). Data obtained in this study suggest that in young subjects, the multifocal CLs studied do not induce large changes in accommodative response compared with the distance-single vision CLs. Spherical aberration reduced significantly with accommodation.
Desai, Ankita R; Maulvi, Furqan A; Pandya, Mihir M; Ranch, Ketan M; Vyas, Bhavin A; Shah, Shailesh A; Shah, Dinesh O
Glaucoma is a chronic disease, which is currently treated using frequent high dose applications of an eye drop solution; this method is tedious, and most of patients are non-compliant to it. Contact lenses are emerging as a convenient option to sustain the release of ophthalmic drugs. However, the incorporation of a drug/formulation changes the optical and physical properties of contact lenses. Contact lens users have also reported pink eye syndrome; this makes contact lenses unsuitable to be accepted as a medical device. The objective of the present study was to design novel timolol and hyaluronic acid (comfort agent)-loaded semi-circular ring-implanted contact lenses that could uphold the release at therapeutic rates without compromising the critical lens properties. The drug-loaded rings were individually implanted within the periphery of the contact lenses using modified cast-moulding technology. Atomic force microscopy showed an average roughness of 12.38 nm for the implanted lens that was significantly lower as compared to that of the Freshlook contact lenses (116.27 nm). A major amount of timolol was leached (from 46.47 to 58.79%) during the monomer extraction and moist sterilization (autoclave) steps; therefore, the lenses were sterilized by radiation and packaged under dry conditions (dehydrated). The in vitro release data showed sustained release of timolol and hyaluronic acid up to 96 h. The in vivo drug release study on rabbit eyes showed the presence of timolol in tear fluid up to 72 h. The in vivo pharmacodynamics studies showed a reduction in IOP till 144 h with a low drug loading (154 μg) as compared to the case of a single instillation eye drop solution (250 μg). This study has demonstrated the successful application of implantation technology to co-deliver timolol and hyaluronic acid from contact lenses for an extended period of time to treat glaucoma.
Schulle, Krystal L; Berntsen, David A; Sinnott, Loraine T; Bickle, Katherine M; Gostovic, Anita T; Pierce, Gilbert E; Jones-Jordan, Lisa A; Mutti, Donald O; Walline, Jeffrey J
Practitioners fitting contact lenses for myopia control frequently question whether a myopic child can achieve good vision with a high-add multifocal. We demonstrate that visual acuity is not different than spectacles with a commercially available, center-distance soft multifocal contact lens (MFCL) (Biofinity Multifocal "D"; +2.50 D add). To determine the spherical over-refraction (SOR) necessary to obtain best-corrected visual acuity (BCVA) when fitting myopic children with a center-distance soft MFCL. Children (n = 294) aged 7 to 11 years with myopia (spherical component) of -0.75 to -5.00 diopters (D) (inclusive) and 1.00 D cylinder or less (corneal plane) were fitted bilaterally with +2.50 D add Biofinity "D" MFCLs. The initial MFCL power was the spherical equivalent of a standardized subjective refraction, rounded to the nearest 0.25 D step (corneal plane). An SOR was performed monocularly (each eye) to achieve BCVA. Binocular, high-contrast logMAR acuity was measured with manifest spectacle correction and MFCLs with over-refraction. Photopic pupil size was measured with a pupilometer. The mean (±SD) age was 10.3 ± 1.2 years, and the mean (±SD) SOR needed to achieve BCVA was OD: -0.61 ± 0.24 D/OS: -0.58 ± 0.27 D. There was no difference in binocular high-contrast visual acuity (logMAR) between spectacles (-0.01 ± 0.06) and best-corrected MFCLs (-0.01 ± 0.07) (P = .59). The mean (±SD) photopic pupil size (5.4 ± 0.7 mm) was not correlated with best MFCL correction or the over-refraction magnitude (both P ≥ .09). Children achieved BCVA with +2.50 D add MFCLs that was not different than with spectacles. Children typically required an over-refraction of -0.50 to -0.75 D to achieve BCVA. With a careful over-refraction, these +2.50 D add MFCLs provide good distance acuity, making them viable candidates for myopia control.
Kwok, L Stephen; Kuznetsov, Valerian A; Ho, Arthur; Coroneo, Minas T
Peripheral light-focusing (PLF) is an occult form of ultraviolet radiation (UVR) hazardous to the human eye. In PLF, obliquely incident light is refracted from the peripheral cornea to concentrated sites inside the anterior segment. In the current study, the directionality of this phenomenon for UVR and whether PLF is established in outdoor settings exposed to sunlight were investigated. The protection provided by a UV-blocking contact lens was also evaluated. UVA and UVB sensors were placed on the nasal limbus of an anatomically based model eye. The temporal limbus was exposed to a UV light source placed at various angles behind the frontal plane. PLF was quantified with the sensor output. The ensemble was mounted in the orbit of a mannequin head and exposed to sunlight in three insolation environments within the region of Sydney, Australia. PLF for UVA and UVB was determined with no eyewear or with sunglasses and commercially available soft contact lenses, with and without UV-blocking capability. The intensity of UVA peaked at approximately 120 degrees incidence, the level at which the UVB response was also at its maximum. The intensification of UVA was up to x18.3. The intensity of PLF for UVA and UVB was reduced by an order of magnitude by a UV-blocking contact lens, whereas a clear contact lenses had a much lesser effect. Only the UV-blocking contact lens achieved a significant effect on UVA and UVB irradiance in the urban, beach, and mountain locales (P < 0.056). The results identify another type of sunlight hazard: the peripheral focusing of obliquely incident light. UVR from albedo (reflected ambient light) is capable of establishing PLF in the anterior segment, but this can be shielded by UV-blocking soft contact lenses. Sunglasses may be unable to shield oblique rays, unless side protection is incorporated. Contact lenses can offer UVR protection against all angles of incidence, including the peak-response angle. They can also protect the eye in settings
... Technique. In: Mannis MJ, Holland EJ, eds. Cornea . 4th ed. Philadelphia, PA: Elsevier; 2017:chap 166. Sierra ... LASIK. In: Yanoff M, Duker JS, eds. Ophthalmology . 4th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 3. ...
Yuksel Elgin, Cansu; Iskeleli, Guzin; Aydin, Ovgu
To investigate changes in tear and ocular surface of patients with keratoconus using rigid gas permeable contact lenses (RGPCL) and compare them against keratoconus patients who were not using lenses as well as a control group of healthy subjects. 24 keratoconus patients using RGPCL (Group 1) 22 patients who were not using lenses (Group 3) and 21 healthy subjects (Group 3) were included in the study. Subjective complaints about the subjects' eyes have been investigated using the ocular-surface disease index (OSDI). After the control of best-corrected visual acuity, anterior chamber and fundus examinations were performed. Schirmer (p-value=0.01) and tear break up mean comparison tests (p-value=0.002) revealed significant differences across different groups but tear osmolarity analysis did not (p-value >0.05). Oxford and OSDI scores were compatible with Schirmer and tear break up test comparisons. (for both p-value=0.001) Moreover, no statistical differences were seen in impression cytology measures between groups. (p-value >0.05) CONCLUSIONS: The erosion in the tear film stability is in line with the erosion in the ocular surface epithelium. Taking into account the statistical indifference between the impression cytology measures across groups, the break up time differences may be attributed to the collagen destruction in tear. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Dry eye is one of the most common complications after laser-assisted in situ keratomileusis (LASIK). The clinical signs of post-LASIK dry eye include positive vital staining of ocular surface, decreased tear film breakup time and Schirmer test, reduced corneal sensitivity, and decreased functional visual acuity. The symptoms and signs last at least 1 month after LASIK. Although the mechanisms for developing post-LASIK dry eye are not completely understood, loss of corneal innervation by flap-making may affect the reflex loops of the corneal-lacrimal gland, corneal-blinking, and blinking-meibomian gland, and blinking-meibomian gland, resulting in decreased aqueous and lipid tear secretion and mucin expression. As LASIK enhancement by flap-lifting induces less dry eye symptoms and signs than first surgery, it is suggested that other factors rather than loss of neurotrophic effect may be involved in the mechanisms of post-LASIK dry eye. The treatments of dry eye include artificial tears, topical cyclosporine, hot compress, punctal plugs, and autologous serum eye drops. For patients with severe preoperative dry eye, a combination of punctal plugs and serum eye drops is required to be used before surgery.
Afzha, Rooh; Chatterjee, Anirban; Subbaiah, Shobha Krishna; Pradeep, Avani Rangaraju
Background: Ultrasonic scaler is a preferential treatment modality among the clinicians. However, the aerosol/splatter generated is a concern for patients and practitioners. Therefore, the purpose of this study was to evaluate contamination of contact lenses of the dentist after scaling and root planing using ultrasonic scalers with and without protective eyewear. Materials and Methods: Thirty patients were randomly selected for scaling and root planing and divided into 2 groups of 15 each. Group A – dentist wearing contact lenses and protective eyewear. Group B - dentist wearing only contact lenses. After scaling and root planing using ultrasonic scalers, the lenses were subjected to culture and 16S rRNA (16S ribosomal RNA) gene sequencing. Results: In Group A – 15 out of thirty samples were contaminated, in Group B – all the thirty samples were contaminated. Most of the samples showed Gram-positive bacteria and 5 samples were contaminated with fungi. 16S rRNA gene sequencing of forty contaminated samples showed that 31 were contaminated with Streptococcus mutans and 9 with Staphylococcus aureus. Conclusion: Keeping in mind the limitation of the study for the absence of negative control, we would like to conclude that dental practitioners should better avoid contact lenses in a dental setup because of the risk of contamination of the contact lenses from the various dental procedures which can produce aerosol/splatter and if worn, it is recommended to wear protective eyewear. PMID:27563200
Afzha, Rooh; Chatterjee, Anirban; Subbaiah, Shobha Krishna; Pradeep, Avani Rangaraju
Ultrasonic scaler is a preferential treatment modality among the clinicians. However, the aerosol/splatter generated is a concern for patients and practitioners. Therefore, the purpose of this study was to evaluate contamination of contact lenses of the dentist after scaling and root planing using ultrasonic scalers with and without protective eyewear. Thirty patients were randomly selected for scaling and root planing and divided into 2 groups of 15 each. Group A - dentist wearing contact lenses and protective eyewear. Group B - dentist wearing only contact lenses. After scaling and root planing using ultrasonic scalers, the lenses were subjected to culture and 16S rRNA (16S ribosomal RNA) gene sequencing. In Group A - 15 out of thirty samples were contaminated, in Group B - all the thirty samples were contaminated. Most of the samples showed Gram-positive bacteria and 5 samples were contaminated with fungi. 16S rRNA gene sequencing of forty contaminated samples showed that 31 were contaminated with Streptococcus mutans and 9 with Staphylococcus aureus. Keeping in mind the limitation of the study for the absence of negative control, we would like to conclude that dental practitioners should better avoid contact lenses in a dental setup because of the risk of contamination of the contact lenses from the various dental procedures which can produce aerosol/splatter and if worn, it is recommended to wear protective eyewear.
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
Background The contaminated contact lens provides Pseudomonas aeruginosa an ideal site for attachment and biofilm production. Continuous contact of the eye to the biofilm-infested lens can lead to serious ocular diseases, such as keratitis (corneal ulcers). The biofilms also prevent effective penetration of the antibiotics, which increase the chances of antibiotic resistance. Methods For this study, 22 Pseudomonas aeruginosa isolates were obtained from 36 contact lenses and 14 contact lens protective fluid samples. These isolates were tested against eight commonly used antibiotics using Kirby-Bauer disk diffusion method. The biofilm forming potential of these isolates was also evaluated using various qualitative and quantitative techniques. Finally, a relationship between biofilm formation and antibiotic resistance was also examined. Results The isolates of Pseudomonas aeruginosa tested were found resistant to most of the antibiotics tested. Qualitative and quantitative biofilm analysis revealed that most of the isolates exhibited strong biofilm production. The biofilm production was significantly higher in isolates that were multi-drug resistant (p < 0.0001). Conclusion Our study indicates that multi-drug resistant, biofilm forming Pseudomonas aeruginosa isolates are mainly involved in contact lens associated infections. This appears to be the first report from Pakistan, which analyzes both antibiotic resistance profile and biofilm forming potential of Pseudomonas aeruginosa isolates from contact lens of the patients with contact lens associated infections. PMID:24134792
Hart, D E; Plociniak, M P; Grimes, G W
Historically, biochemical studies of the interaction between tears and hydrogel contact lenses have not been coordinated with the study of the morphological ultrastructure of the phenomena. Moreover, terms that have distinct and different meanings--pellicle, coating, deposit, and biofilm--have been used interchangeably and often incorrectly when applied within the context of the general field of contact lens biotechnology to describe the tear-polymer interaction. We describe our elucidation of morphological and elemental characteristics of the normal pellicle that forms on the lens surface and urge standard use of the word "pellicle" to specify this entity. Fourteen worn hydrogel lenses (8 Group 1 and 6 Group 4 lenses according to the FDA classification) were rinsed, quartered, and fixed or dried, depending on the analysis to be performed. Scanning electron microscopy (SEM) was used to examine the morphology of the pellicle and quantify its thickness. X-ray analysis was used to detect elements associated with the anterior, central, and posterior portions of the lenses and their relative distribution. A distinctive morphological pellicle ranging from 0.1 to 8.6 microns was present on 12 of the 14 lenses. The pellicle was thicker on the Group 4 lenses than on the Group 1 lenses (P < 0.003). However, the pellicle on Group 1 lenses became thicker with increasing lens age (P < 0.02), but not as thick as on Group 4 lenses. Morphologically distinct lipid or jelly bump deposits were observed at the surface of both lenses from a single patient wearing 2 week old Group 4 lenses. Eleven lenses had sulfur-bearing tear components on the anterior zone. Sulfur was deposited within the matrix of nine lenses. The sulfur containing moieties were more prevalent on Group 4 lenses (P < 0.002). More sulfur was assayed on older lenses (P < 0.004). The anterior lens zone had more sulfur-bearing tear components than did the posterior or center zones (P < 0.05). The physiologically normal
Mao, Xinbang; You, Zhipeng
The aim of the present study was to compare the effectiveness of 25G vitrectomy to standard 20G vitrectomy for treatment of Terson syndrome under Resight non-contact wide-angle lenses. This was a case-control study of 20 patients with Terson syndrome (study group) that underwent 25G vitrectomy under Resight non-contact wide-angle lenses, with those of 20 matched patients that underwent 20G vitrectomy (control group). Medical records were reviewed from between July 2011 and October 2013. Data included results of the Early Treatment Diabetic Retinopathy Study examination, ophthalmology B-scan ultrasonography and fundus photography. The mean age, follow-up time, the preoperative visual acuity of LogMAR and the preoperative intraocular pressure (IOP) were all comparable in the two groups (all P>0.05). There were statistically significant differences in postoperative visual acuity of LogMAR compared with preoperative visual acuity (P<0.001) in both groups, but no difference between the groups (P=0.845). However, the operative times (13.5 min in study group vs. 42 min in control group) and post-operative IOP at day 1 (13.5 vs. 20 mmHg) were significantly reduced in the study group compared to the control group (P<0.001). Therefore, the present findings suggest that 25G Vitrectomy for Terson syndrome under Resight non-contact wide-angle lenses can achieve a significantly shorter operative time and lower post-operative IOP compared with 20G Vitrectomy.
Vermeltfoort, Pit B J; Hooymans, Johanna M M; Busscher, Henk J; van der Mei, Henny C
The killing efficacies of multipurpose lens care solutions on planktonic and biofilm bacteria grown in polypropylene contact lens storage cases with and without silver impregnation and effects on bacterial transmission from storage cases to silicone hydrogel contact lenses were investigated. For transmission studies, biofilms of Staphylococcus aureus 835 or Pseudomonas aeruginosa no. 3 were grown on lens storage cases and incubated with a contact lens in different multipurpose lens care solutions (Opti-Free(R)Express(R), ReNu(R) MultiPlus(R), and SoloCare Aquatrade mark) or 0.9% NaCl. In addition, planktonic bacteria were directly suspended in multipurpose solutions and their killing efficacies were determined. The numbers of transmitted live and dead bacteria on the lenses were measured using a combination of plate counting and fluorescence microscopy. The highest killing efficacies were shown by Opti-Free(R) Express(R) for planktonic as well as for biofilm bacteria. Silver impregnation of lens cases in combination with the prescribed solution increased the killing efficacy for P. aeruginosa in biofilms, whereas effects for S. aureus were minor. Lowest numbers of live and dead bacteria were transmitted to a lens in Opti-Free(R) Express(R) multipurpose solution, with no significant differences between lens types and no effects of silver impregnation. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008. (c) 2008 Wiley Periodicals, Inc.
Cowell, B A; Willcox, M D; Schneider, R P
Adhesion of bacteria to hydrogel lenses is thought to be an initial step of ocular colonization allowing evasion of normal host defences. The salt concentration of media is an important parameter controlling microbial adhesion. Salinity varies from 0.97% NaCl equivalents in the open eye to 0.89% in the closed eye state. In this study, the effect of sodium chloride in the concentration range of 0.8-1.0% (w/v) NaCl on adhesion of ocular bacteria to soft contact lenses was investigated using a static adhesion assay. Pseudomonas aeruginosa was found to adhere to lenses in significantly greater amounts than Serratia marcescens, Flavobacterium meningosepticum, Stenotrophomonas maltophilia and Staphylococcus intermedius. Increasing NaCl from 0.8% to 1.0% (w/v) increased adhesion of all bacteria tested. This adhesion was strong since the organisms could not be removed by washing in low ionic buffer. Adhesion of these organisms did not correlate with their cell surface properties as determined by bacterial adhesion to hydrocarbons (BATH) and retention on sepharose columns.
Boost, Maureen V; Cho, Pauline
The purpose of this study is to determine if there are changes in the ocular flora of overnight orthokeratology (ortho-k) patients, and the levels of contamination of their lenses and lens accessories, and to correlate compliance with levels of contamination. Normal ocular flora of 41 subjects was determined twice before commencing ortho-k lens wear by culture of the lower conjunctiva. Further specimens were collected on six follow-up visits after beginning lens wear, as were samples from their lenses, cases, and suction holders. A questionnaire on lens care was administered after the fifth visit. Three subjects provided conjunctival samples yielding Staphylococcus aureus on one occasion before lens wear, one being positive for this organism after beginning lens wear. Of 38 subjects yielding no growth or only normal eye flora before use, 28 remained free of ocular pathogens after beginning lens wear. Only four subjects had positive cultures on more than one occasion after lens wear. There was no significant difference in isolation levels of pathogens with lens wear (p = 0.423). Lens culture of 54% of subjects yielded no growth or normal flora only; lenses of 16 subjects yielded potential pathogens, including three subjects contaminated on more than one occasion. Lens isolates did not match the organisms transiently colonizing the eye. Lens case, the most frequently contaminated item, was associated with lens contamination (p < 0.001), the same organism being isolated from both items in 11 subjects. Lens suction holder was less frequently contaminated. Neither lens case nor suction holder contamination was associated with isolates from the eye. Reported good compliance correlated with lack of contamination in all but one subject. The most frequent breaches in the lens care protocol were failure to clean, disinfect, and replace the lens case. Ocular flora was not altered by ortho-k lens wear over an extended period, and patients remained free of infection
Schafer, Jeffery; Reindel, William; Steffen, Robert; Mosehauer, Gary; Chinn, Joseph
Background Sustained digital display viewing reduces eye blink frequency and tear film stability. To retain water and preserve a smooth optical surface, contact lens manufacturers have integrated the humectant polyvinylpyrrolidone (PVP) into silicone hydrogel contact lenses. In this study, extended blink time (EBT) was used to assess visual stability over a prolonged blink interval of two PVP-containing silicone hydrogel lenses, samfilcon A (SAM) and senofilcon A (SEN). Materials and methods This randomized, bilateral, masked, crossover study assessed lens performance in ten subjects after 16 hours of wear. EBT, ie, the time elapsed between cessation of blinking and blur-out of a threshold letter on the acuity chart, was measured. At the end of the wear period, subjects reported duration of computer use and rated visual quality (VQ) and comfort while wearing the assigned lens, and the investigator evaluated lens surface wetting characteristics. Each lens was removed and immediately weighed to determine total water content. Results EBTs were 10.42 seconds for SAM and 8.04 seconds for SEN (p = 0.015). Subjective ratings of VQ after 16 hours of wear were 84.6 for SAM and 74.4 for SEN (p = 0.049). Comfort ratings were 85.9 for SAM and 80.2 for SEN (p > 0.05). Median times of computer use were 6–8 hours for both lens types. Post blink, 70.0% of SAM and 30.0% of SEN lenses were completely wet (p = 0.021). Total water content after wear was 43.7% for SAM and 35.5% for SEN (p < 0.001). Conclusion EBT measurement indicated more stable vision with the PVP-containing SAM polymer compared with the PVP-containing SEN polymer. The SAM polymer also demonstrated better surface wetting and maintained higher water content after a prolonged period of wear. EBT can be valuable in assessing vision stability of patients after hours of computer use. PMID:29765195
Migonney, V; Lacroix, M D; Ratner, B D; Jozefowicz, M
Epoxy ring-opening functionalization of polymers at random sites along chains with various chemical groups has been demonstrated. The reaction is performed in an aqueous solution under mild conditions in order to minimize degradation of the macromolecular chains. Silicone lenses made of copolymers with epoxy side chains were functionalized with 4-hydroxybutyric acid, sodium salt. The carboxylated silicone derivatives were characterized by ESCA and radiotracers. A mean value of 30% reaction yield was concluded, based upon data from both methods; nevertheless, the latter can be improved up to 50% or more if the conditions of preparation of the epoxydized silicone lenses are optimized. Derivatized silicones were coated in the wells of culture plates to evaluate the cell compatibility of these new polymers with a fibroblast cell line (McCoy's). No cellular toxicity was observed.
Opdahl, Aric; Kim, Seong H; Koffas, Telly S; Marmo, Chris; Somorjai, Gabor A
The surface mechanical properties of poly(hydroxyethyl)methacrylate (pHEMA)-based contact lenses were monitored as a function of humidity by atomic force microscopy (AFM). Surface viscoelastic and adhesion values were extracted from AFM force versus distance interaction curves and were found to be strongly dependent on the bulk water content of the lens and on the relative humidity. At low relative humidity, 40-50%, the dehydration rate from the surface is faster than the hydration rate from the bulk, leading to a rigid surface region that has mechanical properties similar to those measured on totally dehydrated lenses. At relative humidity values > 60%, the dehydration rate from the lens surface rapidly decreases, leading to higher surface water content and a softer surface region. The results indicate that, in an ocular environment, although the bulk of the pHEMA contact lens is hydrated, the surface region may be in a transition between a dehydrated glassy state and a hydrated rubbery state. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 350-356, 2003
Fabres, Laura Fuhrich; Maschio, Vinicius José; Santos, Denise Leal Dos; Kwitko, Sergio; Marinho, Diane Ruschel; Araújo, Bruno Schneider de; Locatelli, Claudete Inês; Rott, Marilise Brittes
Several strains of free-living amoebae belonging to the genus Acanthamoeba can cause a painful sight-threatening disease of the cornea known as Acanthamoeba keratitis (AK). The numbers of AK cases keep rising worldwide mainly due to an increase in contact lens wearers and lack of hygiene in the maintenance of contact lenses and their cases. We report a case of AK in a healthy young woman admitted to the Hospital de Clinicas in Porto Alegre, southern Brazil. Corneal scrapings were examined for the presence of Acanthamoeba strains. The initial isolate was characterized by morphological and genotypic properties. The isolate belonged to group III according to Pussard and Pons' cyst morphology. Analysis of its 18S rDNA sequence identified the isolate as genotype T4. The T4 genotype is the most commonly reported among keratitis isolates and the most common in environmental samples.
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.
Pearson, Richard M; Evans, Bruce J W
To compare the repeatability and validity of measurements of the back vertex power (BVP) of spherical soft contact lenses made in-air using the method specified in the International Standard (ISO 18369-3:2006) with the corresponding values when BVP was calculated from measurements made using a wet cell and focimeter method that is not approved by this Standard. The BVP of 20 hydrogel and 20 silicone hydrogel lenses, with labelled powers ranging from +8.00 to -12.00 D, were measured with a focimeter by two operators on two occasions in-air in accordance with the relevant International Standard. Equivalent sets of measurements were made with the lenses immersed in-saline within a wet cell and their BVPs in-air were calculated. The validity of each method was assessed by comparing their results with an instrument that used the Hartmann method. The reliability results were generally a little better for the in-saline measurements than for the in-air measurements, although all reliability data demonstrated absolute values of mean errors (inter-operator and inter-session) that were <0.05 D for hydrogel lenses and <0.07 D for silicone hydrogel lenses. The in-air 95% confidence intervals were <0.45 D and <0.40 D for hydrogel and silicone hydrogel lenses, respectively and in-saline <0.39 and <0.31 D for hydrogel and silicone hydrogel lenses, respectively. The validity data revealed a relationship between measurement error and BVP for the in-air data (the focimeter overestimates the power of high plus and high minus lenses compared with the Hartmann instrument) and possibly a more complex relationship for the in-saline data. The 95% limits of agreement indicate better agreement for the in-saline validity data (-0.55 to +0.48 D for hydrogel lenses and -0.42 to +0.54 D for silicone hydrogel lenses) than those obtained in-air (-0.64 to +0.68 D for hydrogel lenses and -0.57 to +0.44 D for silicone hydrogel lenses). Using equipment readily available in a clinical setting, the wet
Michaud, Langis; Bennett, Edward S; Woo, Stephanie L; Reeder, Renee; Morgan, Bruce W; Dinardo, Amy; Harthan, Jennifer S
This study aims to address the clinical performance of a large diameter rigid gas permeable lens (LRGP) in a group of subjects with low-to-moderate (0.75-2.75 D) refractive astigmatism. An additional goal was to determine whether soft toric or LRGP contact lenses performed better objectively in the correction of astigmatism and to determine which modality is preferred by subjects. This was a multisite prospective cross-over clinical study. Ten asymptomatic contact lens wearers per site (four university clinics) were recruited and randomly assigned to group A or group B. Group A was assigned to start wearing Comfilcon A soft toric lens first, for two weeks, and then crossed over to LRGP lenses (Boston XO, 14.3 mm diameter miniscleral lens). Group B initially wore LRGP lenses and then crossed over to soft toric lenses. For each type of lens worn, low-contrast and high-contrast visual acuity (VA) were evaluated at distance. At the conclusion of the study, after two months, all subjects completed a questionnaire in which they were asked to indicate their preference for one type of lens (soft toric or LRGP) and to rate the quality of vision in day-to-day activities. Thirty-six of 38 (94.7%) subjects completed the study with 75% preferring the vision of the LRGP lens as compared to the soft toric lenses worn in the study. 52.7% expressed a preference to continue with this modality despite only 38.8% reporting that these LRGP lenses are easy or very easy to handle. Wear time, subjective comfort, and subjective vision ratings exhibited no significant difference between the two groups. In a population of asymptomatic contact lens wearers, LRGP lenses can be considered as a good alternative to soft toric lenses for the correction of refractive astigmatism.
... this page: //medlineplus.gov/ency/presentations/100206.htm Lasik eye surgery - series—Normal anatomy To use the ... A.M. Editorial team. Related MedlinePlus Health Topics Laser Eye Surgery A.D.A.M., Inc. is accredited by ...
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.
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
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
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. 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). 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. 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.
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
Svitova, Tatyana F; Lin, Meng C
To explore interfacial behaviors and effects of temperature and dilatation on dynamic properties of multilayered human tear lipids extracted from silicone hydrogel (SiH) lenses worn by asymptomatic Asian and white subjects. 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 electrolyte (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 of 22 to 45°C for their viscoelastic property assessment. Isocycles for Asian and white 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 white. The elastic modulus E∞ for white 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 white lipids when temperature increased from 22.0 to 36.5°C. However, for white lipids, E∞ reduced considerably at temperatures higher than 42.0°C, whereas t remained unchanged. For Asian lipids, both E∞ and t started to decline as temperature increased to 38°C and higher. Higher elastic modulus of white 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 white lipids may be associated with the differences in their chemical compositions.
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
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.
Gargallo, Ana; Arines, Justo
We have adapted low cost webcams to the slit lamps objectives with the aim of improving contact lens fitting practice. With this solution we obtain good quality pictures and videos, we also recorded videos of eye examination, evaluation routines of contact lens fitting, and the final practice exam of our students. In addition, the video system increases the interactions between students because they could see what their colleagues are doing and take conscious of their mistakes, helping and correcting each others. We think that the proposed system is a low cost solution for supporting the training in contact lens fitting practice.
Coral-Ghanem, Cleusa; Alves, Milton Ruiz
To evaluate the clinical performance of Monocurve and Bicurve (Soper-McGuire design) rigid gas-permeable contact lens fitting in patients with keratoconus. A prospective and randomized comparative clinical trial was conducted with a minimum follow-up of six months in two groups of 63 patients. One group was fitted with Monocurve contact lenses and the other with Bicurve Soper-McGuire design. Study variables included fluoresceinic pattern of lens-to-cornea fitting relationship, location and morphology of the cone, presence and degree of punctate keratitis and other corneal surface alterations, topographic changes, visual acuity for distance corrected with contact lenses and survival analysis for remaining with the same contact lens design during the study. During the follow-up there was a decrease in the number of eyes with advanced and central cones fitted with Monocurve lenses, and an increase in those fitted with Soper-McGuire design. In the Monocurve group, a flattening of both the steepest and the flattest keratometric curve was observed. In the Soper-McGuire group, a steepening of the flattest keratometric curve and a flattening of the steepest keratometric curve were observed. There was a decrease in best-corrected visual acuity with contact lens in the Monocurve group. Survival analysis for the Monocurve lens was 60.32% and for the Soper-McGuire was 71.43% at a mean follow-up of six months. This study showed that due to the changes observed in corneal topography, the same contact lens design did not provide an ideal fitting for all patients during the follow-up period. The Soper-McGuire lenses had a better performance than the Monocurve lenses in advanced and central keratoconus.
Shen, Elizabeth P; Tsay, Ruey-Yug; Chia, Jean-San; Wu, Semon; Lee, Jing-Wen; Hu, Fung-Rong
To determine the distribution of invasive and cytotoxic genotypes among ocular isolates of P. aeruginosa and investigate the influence of the type III secretion system (T3SS) on adhesion to conventional, cosmetic, and silicone hydrogel contact lenses (CL). Clinical isolates from 2001 to 2010 were analyzed by multiplex PCR for exoS, exoU, and exoT genes. Bacterial adhesion to etafilcon, nelfilcon (gray colored), balafilcon, and galyfilcon CL with or without artificial tear fluid (ATF) incubation were compared. Surface characteristics were determined with scanning electron microscopy (SEM). Among 87 total isolates, 64 strains were from microbial keratitis cases. CL-related microbial keratitis (CLMK) isolates were mostly of the cytotoxic genotype (expressing exoU) (P = 0.002). No significant differences were found in bacterial adhesion to all types of CL between the genotypes under T3SS-inducing conditions. A trend for least bacterial adhesion of galyfilcon compared to the other CL was noted for both genotypes. Needle complex pscC mutants adhered less to all materials than the wild type (P < 0.05), indicating a role of the T3SS in contact lens adhesion. ATF-incubated CL had significantly more bacterial adhesion (P < 0.05). SEM showed most of the bacteria adhering on CL surfaces. CLMK isolates were mostly of cytotoxic genotype. Different genotypes did not significantly differ in its adhesion to various CL. T3SS and other adhesins are involved in bacteria-contact lens adhesion through complex interactions. Contact lens materials may also play an important role in the adherence of both genotypes of P. aeruginosa.
Walsh, James E; Bergmanson, Jan P G; Saldana, Gerardo; Gaume, Amber
Peak solar UV radiation (UVR) intensities are typically experienced in summer months. People living in the southern states of the United States, where the UVR frequently exceeds the recommended minimum erythema dose (MED), are at particular risk, especially outdoor workers. The present study analyzed summertime MED readings in Houston, TX, to assess the frequency of intensities regarded as unhealthy. The study also sought to assess whether UV-blocking hydrogel contact lenses provide ocular protection from these high doses. Readings, taken at midday using a UVR biometer, were analyzed to assess the potential UVR risk. The spectral response of the meter, modified by the spectral transmission curves of the contact lenses, allowed us to mathematically assess the ocular protection provided. In addition, ambient UVR measurements were taken at midday, using a portable UVR radiometer. The detector was adapted so that a standard diameter hydrogel contact lens could be placed over it to quantify the UV-blocking capabilities of the lens. The MED readings showed that the recommended safety standards were exceeded approximately at local midday 90% of the time. Model calculations and empirical data demonstrated that contact lenses attenuated the MED readings by up to 90%, bringing them well within the recommended Environmental Protection Agency safety standards. The efficacy of the model used in this study was verified through direct comparison of the modeled and measured data. UV-blocking hydrogel soft contact lenses reduce the MED to the human eye and therefore limit the lifetime ocular dose. These lenses are highly recommended to prevent the development of UVR-related ocular pathologic conditions.
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.
Ding, Hui; Pu, Aijun; He, Hong; Xie, Ruo Zhong; Yang, Jun; Liao, Aiping; Gao, Shaohui; Zhong, Xingwu
This study compared the effect of orthokeratology (OK) lens wear on corneal topography and microstructure between the 1-night and 30-night wearers to predict any adverse responses of the eyes to long-term OK lens wear. Nine rhesus monkeys with one eye wearing an OK lens and the fellow eye wearing a rigid gas permeable (RGP) lens were used in this study. The lenses were worn for 11 hours, with the measurement of corneal curvature and thickness and axial components of the eye at 0 night (n = 9), 1 night (n = 9), and 30 nights (n = 6). Histology was performed at 1 and 30 nights of lens wear. Corneal surface power in the 3-mm central region was reduced in the OK eye when compared with the RGP eye (P < 0.05). Central corneal thickness was only reduced in 30 nights of OK lens wear (P < 0.05). Under light microscopy, the 1-night OK or RGP eyes showed normal morphology in all layers of the cornea. The 30-night OK eyes showed a thinned central corneal epithelium and a thickened but less stratified paracentral corneal epithelium when compared with the 30-night RGP eyes. Under electron microscopy, intercellular junctions of corneal epithelium in the 30-night OK eyes were much looser than those in the 1-night OK eyes. However, the density and morphology of hemidesmosomes were similar between the OK and RGP eyes at 30 nights of lens wear. Overnight OK can change the corneal curvature through anterior corneal remodeling, resulting in an effective correction of myopia. However, a decrease in intercellular junctions during long-term wear may compromise the functions of the corneal epithelium as a border mechanical barrier.
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.
immediately. Special instructions were provided to these flight surgeons regarding identification, treatment , and disposition of these subjects. This...conjunctivitis; two cases of anterior uveitis /iritis; and one case of a severe allergic reaction. Many of the above conditions were probably not...contact lens related, although the anterior uveitis cases may have been related to a temporary tight lens condition. In order to rule out a tight lens fit
Raali, E; Vaahtoranta-Lehtonen, H H; Lehtonen, O P
BEN22 detergent was studied for its ability to detach Acanthamoeba from soft contact lenses without mechanical cleaning or separate cleaning agents. Trophozoites of Acanthamoeba castellanii and A. polyphaga were adhered onto nonionic, high water content soft contact lenses. The lenses were immersed for 2 hours in contact lens care solutions and the remaining trophozoites were counted microscopically. The counts were compared to the counts on the same lens before treatment. BEN22 (50:50 mixture of L-alpha-L-rhamnopyranosyl-beta-hydroxydecanoyl-beta-hydroxydecanoate and 2-O-alpha-L-rhamnopyranosyl-alpha-L-rhamnopyranosyl-beta-hydroxydecanoyl-beta-hydroxydecanoate) (Kassell Industries, Inc., Wisconsin Dells, WI) in a concentration of 0.05% detached the trophozoites to a statistically significant greater extent than saline, but commercial ReNu Multi-Purpose Solution (Bausch & Lomb, Italy) and BioSoak (Finnsusp Ltd., Finland) did so as well. ReNu Multi-Purpose Solution was more effective than 0.005% BEN22 in detaching the trophozoites of both of the Acanthamoeba strains. After the 2 hour immersion period, a maximum of 97% of the initial trophozoites were detached. The variation between individual lenses was significantly greater than that within the different areas of one lens. BEN22 had no reliable detaching effect on Acanthamoeba. The variation between lenses was great, and the rate of detachment was low with all the agents tested indicating that immersion and rinsing in the solutions tested cannot be considered as a safe substitute for proper disinfection against Acanthamoeba in contact lens care.
Golebiowski, Blanka; Papas, Eric B; Stapleton, Fiona
Deprivation of oxygen to the ocular surface during contact lens wear has been implicated in the alteration of sensory function. This study investigates whether increasing oxygen availability through discontinuation of contact lens wear or transfer into highly oxygen transmissible (high Dk/t) lenses leads to a change in corneal or conjunctival sensitivity. Twenty-seven long-term extended wearers of low Dk/t soft contact lenses ceased lens wear for 1 week and were refitted with high Dk/t silicone hydrogel lenses. A control group of 25 nonwearers matched for age and sex was also recruited. Central corneal and inferior conjunctival sensitivity were measured using an air-jet aesthesiometer. Threshold was determined using a staircase technique. Measurements were taken during low Dk/t lens wear; after 1 week of no wear; and after 1, 3, 6, and 12 months of high Dk/t lens wear. Measurements were carried out on one occasion on the nonwearers. Corneal sensitivity decreased 1 week after discontinuation of low Dk/t lenses and no further change in sensitivity occurred with high Dk/t lens wear. Conjunctival sensitivity did not change over the same time frame. Ocular surface sensitivity in long-term low Dk/t soft lens wearers was similar to that of nonwearers. Sensitivity was higher in females than males in the nonwearers, but not in the lens-wearing group. An interaction of sex on change in conjunctival threshold was found in the lens wearers. These findings indicate that factors other than oxygen availability alone determine sensitivity of the ocular surface. Silicone hydrogel contact lenses appear to have only a minor impact on ocular surface sensitivity in previous lens wearers.
Tsai, Tsung-Han; Peng, Kai-Ling; Lin, Chien-Jen
Background Laser in situ keratomileusis (LASIK) is the most common and popular procedure performed for the correction of refractive errors in the last two decades. We report a case of traumatic flap displacement with flap folding which occurred 3 years after LASIK was performed. Previous literature suggests that vision prognosis would be closely related to proper and prompt management of traumatic flap displacement with flap folding 3 years after LASIK. Case presentation A 23-year-old female presented to our hospital who had undergone uneventful LASIK in both eyes 3 years prior. Unfortunately, she had suffered a blunt trauma in her right eye in a car accident. A late onset of corneal flap displacement was found with upper and lower portion of the flap being folded inside the corneal bed. Surgical intervention for debridement with subsequent reposition of corneal flap was performed as soon as possible in the operating room. A bandage contact lens was placed, and topical antibiotic and corticosteroids were given postoperatively. Two days after the operation, the displaced corneal flap was found to be well attached smoothly on the corneal bed without folds. The best-corrected visual acuity was 6/6 with refraction of −0.75 D to 1.0 D ×175° in her right eye 1 month later. Literature review We reviewed a total of 19 published cases of late-onset traumatic flap dislocations or displacements after LASIK with complete data from 2000 to 2014. Conclusion Traumatic displacement of corneal flaps after LASIK may occur after blunt injury with specific direction of force to the flap margin, especially tangential one. According to the previous literature, late-onset traumatic flap displacement may happen at any time after LASIK and be caused by various types of injuries. Fortunately, good visual function could mostly be restored with immediate and proper management. PMID:28458585
Tsai, Tsung-Han; Peng, Kai-Ling; Lin, Chien-Jen
Laser in situ keratomileusis (LASIK) is the most common and popular procedure performed for the correction of refractive errors in the last two decades. We report a case of traumatic flap displacement with flap folding which occurred 3 years after LASIK was performed. Previous literature suggests that vision prognosis would be closely related to proper and prompt management of traumatic flap displacement with flap folding 3 years after LASIK. A 23-year-old female presented to our hospital who had undergone uneventful LASIK in both eyes 3 years prior. Unfortunately, she had suffered a blunt trauma in her right eye in a car accident. A late onset of corneal flap displacement was found with upper and lower portion of the flap being folded inside the corneal bed. Surgical intervention for debridement with subsequent reposition of corneal flap was performed as soon as possible in the operating room. A bandage contact lens was placed, and topical antibiotic and corticosteroids were given postoperatively. Two days after the operation, the displaced corneal flap was found to be well attached smoothly on the corneal bed without folds. The best-corrected visual acuity was 6/6 with refraction of -0.75 D to 1.0 D ×175° in her right eye 1 month later. We reviewed a total of 19 published cases of late-onset traumatic flap dislocations or displacements after LASIK with complete data from 2000 to 2014. Traumatic displacement of corneal flaps after LASIK may occur after blunt injury with specific direction of force to the flap margin, especially tangential one. According to the previous literature, late-onset traumatic flap displacement may happen at any time after LASIK and be caused by various types of injuries. Fortunately, good visual function could mostly be restored with immediate and proper management.
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.
Qu, Wenwen; Hooymans, Johanna M M; Qiu, Jun; de-Bont, Nik; Gelling, Onko-Jan; van der Mei, Henny C; Busscher, Henk J
Surface properties of lens cases are determinant for their cleanability and for microbial transmission from lens cases to contact lenses (CLs). PEG-polymer-brush-coatings are known to decrease microbial adhesion more than other surface-coatings. Here, we applied a robust, silica nanoparticles-based brush-coating to polypropylene cases to evaluate their ease of cleaning and probability of bacterial transmission to CLs. Adhesion forces of nine bacterial strains (Pseudomonas, Staphylococci, and Serratia) to rigid CLs, polypropylene, and silica nanoparticles-based brush-coated polypropylene were measured using atomic-force-microscopy and subjected to Weibull analyses to yield bacterial transmission probabilities. Biofilms of each strain were grown in coated and uncoated cases and rinsed with a NaCl or antimicrobial lens care solution. Residual, viable organisms were quantified. Bacterial adhesion forces of all strains were significantly, up to tenfold smaller on brush-coated than on uncoated polypropylene. This yielded, higher transmission probabilities to a CL, but mild-rinsing yielded 10-100 fold higher removal of bacteria from brush-coated than from polypropylene cases. Moreover, due to weak adhesion forces, bacteria on brush-coated cases were two-to-three fold more susceptible to an antimicrobial lens care solution than on polypropylene cases. Therewith, the design of lens case surfaces is a compromise between ease of cleaning and transmission probability to CLs. Copyright © 2013 Wiley Periodicals, Inc.
Riley, Colleen; Young, Graeme; Chalmers, Robin
Many soft contact lens wearers have symptoms or signs that compromise successful lens wear. This study estimated the prevalence of problems in current wearers of soft contact lenses and tested the effect of refitting patients with senofilcon A silicone hydrogel lenses (ACUVUE Oasys). Prevalence was estimated from 1,092 current lens wearers for frequent or constant discomfort or dryness, at least 2 hours of uncomfortable wear, at least grade 2 limbal or bulbar hyperemia (0-4), or at least grade 3 corneal staining (0-15). In the second part of the study, 112 of the 564 wearers classified as problem patients were refitted with senofilcon A lenses and reassessed 2 weeks later. Fifty-two percent (564 of 1,092) had some qualifying criteria, with dryness reported by 23%, discomfort by 13%, and at least 2 hours of uncomfortable wear by 27%. Six percent of subjects had qualifying limbal hyperemia; 10% had bulbar hyperemia; and 12% had corneal staining. After refitting 112 problem patients, 75% had less dryness; 88% had better comfort (P<0.0001 each); and 76% had fewer uncomfortable hours of wear (P=0.004). Although the average wearing time was unchanged, comfortable wearing time increased significantly (10.4 to 11.6 hours) (P=0.004). All (35 of 35) eyes with qualifying limbal hyperemia before the refit also improved (P<0.0001), as did 80% (40 of 50) of those with bulbar hyperemia (P<0.0001) and 76% (26 of 34) of those with corneal staining (P=0.005). Most soft lens wearers encounter clinically significant signs or symptoms with their current contact lenses. Refitting with new-generation silicone hydrogel lenses (senofilcon A) can alleviate some of these common problems.
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.
Simon, M; Coiffard, L J; Rivalland, P; De Roeck-Holtzhauer, Y
This work aims to characterize products designed for cleaning contact lenses and particularly their physicochemical properties, their efficiency and their ocular irritancy potential compared to the main requirements of eye-washes. The physicochemical controls include pH determination, viscosity and freezing point depression. In addition, we carried out the hydrogen peroxide assay for products containing this active substance. A microbiological control was performed when opening the product and after simulation of a 21-day aging. We determined the decontaminating efficacy of the products on four bacterial strains and a fungal strain. Finally, we tested their ocular allowance by an in vitro test. The pH values obtained ranged from 3.2 (oxygenated water solutions) to 7.6. The viscosity was close to a water solution one (about 1 centipoise). The different assays showed hydrogen peroxide content similar to that stated on the package: rate averaged to 3% and was negligible after neutralization. At opening and after simulation the bacteriological quality was excellent. Finally, decontaminating efficiency against germs was very good for the products tested. The products were classified as non-irritant by the ocular irritancy test. The results obtained show that the products tested met the reference criteria, particularly eye-wash criteria.
Sumide, Taizo; Tsuchiya, Toshie
To ensure the effects of multipurpose solutions (MPS) for hydrogel contact lenses on the cornea, the inhibitory activity of three types of MPS on corneal cells has been evaluated with the use of scrape loading and dye transfer assay (SLDT assay) and Western blotting on rabbit corneal keratocytes (RC4). In SLDT assay, MPS-A and poloxamine showed dose-dependent inhibitory activity, suggesting the inhibitory action of MPS-A and poloxamine to gap junctional intercellular communication (GJIC) in the tested cells. Moreover, after treatment with MPS-A, the GJIC was initially inhibited within 4 h, and thereafter gradually turned to an approximately 60% level of the initial value. When MPS-A was removed from the incubation media after exposure of the cells, the recovery of GJIC was time dependent and returned to approximately initial levels at 8 h. Complete recovery was established after approximately 24 h. These findings suggested that the inhibitory action of MPS-A on corneal keratocytes was reversible. This inhibition was accompanied by a decrease in the quantity of connexin-43, which is a major protein constituting the gap junctional channel of these cells, and its change in the phosphorylation state. Taken together, it was suggested that MPS-A interacts with connexin-43, inducing an inhibitory action on GJIC. (c) 2002 Wiley Periodicals, Inc.
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.
Yang, Mei; Yang, Yangfan; Lei, Ming; Ye, Chengtian; Zhao, Chunshun; Xu, Jiangang; Wu, Kaili; Yu, Minbin
Pirfinedone (PFD) is a novel agent which has the potential to prevent scarring in the eyes. The 0.5% PFD eye drops exhibits poor bioavailability. Whereas, the feasibility of using contact lens as ocular drug delivery device initiated novel possibilities. To evaluate the delivery of PFD by soft contact lens (SCL) in vivo, we screened the most suitable lens material for PFD among various commercially available SCL materials in vitro. Firstly, 11 different SCLs (-1.00 diopter) were respectively soaked in 2 ml of 0.05% PFD-loading solution for 24 h to fully absorb drug, and then placed in fresh phosphate buffered saline (PBS) to release the drug. PFD concentration in PBS was determined by ultraviolet absorbance at 310 nm. Secondly, by immersing in 2 ml of 0.5% PFD eye drops for 24 h, the polymacon lens (0.00 diopter) was then placed on the cornea of New Zealand rabbits. PFD concentrations were detected by high performance liquid chromatography (HPLC) in tears, aqueous humor, conjunctiva, cornea, and sclera at different time points. PFD showed some affinity for pHEMA-based lenses and the polymacon lens more slowly released more amount of PFD than any other lens in vitro (p < 0.001). Compared with eye drops, drug-loaded SCLs greatly enhanced the retention time and concentrations of PFD in cornea and aqueous humor and consequently improved the bioavailability of PFD. Polymacon-based SCL is probably a promising vehicle to be an effective ophthalmic delivery system for PFD.
Shtein, Roni M
Laser-assisted in situ keratomileusis (LASIK) is a frequently performed corneal refractive surgery with excellent refractive outcomes. The most common complication of LASIK is dry eyes, with virtually all patients developing some degree of dryness in the immediate postoperative period. Identifying preoperative dry eyes, and conscientious attention and treatment in the perioperative time period, can lead to enhanced patient satisfaction and more accurate visual outcomes. Improved understanding of the development of dry eyes after LASIK will advance our understanding of the complex pathophysiology of dry eye disease. PMID:22174730
O'Brien, C; Charman, W N
After a preliminary investigation of the effects of tool feed rate and spindle speed on the surface roughness of unhydrated, lathe-cut polymacon surfaces, a laboratory and clinical comparison was made between lenses with identical parameters except that the lathe-cut posterior surface was left unpolished in the "test" lenses and was polished in the "control" lenses. The lenses had moulded anterior surfaces. Laboratory comparisons included surface roughness, lens power and its uniformity across the surface. Double-blind clinical trials over 4-hour (27 subjects) and 1-month (10 subjects) periods, involved one eye of each subject wearing a "test" lens and the other, a "control" lens. No clinically significant differences were found between the results for the test and control lenses. It is concluded that today's lathing technology makes a final polishing stage unnecessary.
Versura, Piera; Profazio, Vincenzo; Balducci, Nicole; Campos, Emilio C
To evaluate the efficacy and tolerability of Xiloial(®) monodose eyedrops in the treatment of patients suffering from subjective symptoms of discomfort related to disposable soft contact lens (dSCL) wear. Fifteen (12 female, three male, medium age 39 ± 9 years) dSCL wearers were enrolled. Inclusion criteria were Ocular Surface Disease Index (ODSI) symptom questionnaire score >12, tear film break-up time (TFBUT) <10 sec, Schirmer test I >10 mm over five minutes, mild punctuate keratopathy, and conjunctival staining (Oxford grading ≤4). Monodose Xiloial eyedrops were administered three times daily for a two-month period. Patients were evaluated at enrollment, after three days of washout (baseline), and after one and two months of treatment, by OSDI score, Schirmer test I, TFBUT, ferning test, ocular surface damage (Oxford grade), and serum albumin in tears (index of passive exudation related to serum leakage). At endpoint versus baseline, respectively, the mean ± standard deviation of all variables improved as follows: OSDI (8.5 ± 3 versus 20.2 ± 1.6); TFBUT (9.6 ± 1.1 versus 7.1 ± 1.0); Oxford grading (0.5 ± 0.1 versus 3.6 ± 0.8); ferning test (2 ± 1 versus 2.4 ± 0.5); and Schirmer test I (14.6 ± 1.1 versus 12 ± 2.1), with P < 0.05 for all variables (Friedman and Wilcoxon tests). Tolerability was high, with no adverse events noted. A two-month treatment with Xiloial showed good tolerance and appeared to reduce ocular surface damage and symptoms of discomfort.
Gorbet, Maud; Peterson, Rachael; McCanna, David; Woods, Craig; Jones, Lyndon; Fonn, Desmond
A pilot study was conducted to evaluate human corneal epithelial cell shedding in response to wearing a silicone hydrogel contact lens/solution combination inducing corneal staining. The nature of ex vivo collected cells staining with fluorescein was also examined. A contralateral eye study was conducted in which up to eight participants were unilaterally exposed to a multipurpose contact lens solution/silicone hydrogel lens combination previously shown to induce corneal staining (renu® fresh™ and balafilcon A; test eye), with the other eye using a combination of balafilcon A soaked in a hydrogen peroxide care system (Clear Care®; control eye). Lenses were worn for 2, 4 or 6 hours. Corneal staining was graded after lens removal. The Ocular Surface Cell Collection Apparatus was used to collect cells from the cornea and the contact lens. In the test eye, maximum solution-induced corneal staining (SICS) was observed after 2 hours of lens wear (reducing significantly by 4 hours; p < 0.001). There were significantly more cells collected from the test eye after 4 hours of lens wear when compared to the control eye and the collection from the test eye after 2 hours (for both; n = 5; p < 0.001). The total cell yield at 4 hours was 813 ± 333 and 455 ± 218 for the test and control eyes, respectively (N = 5, triplicate, p = 0.003). A number of cells were observed to have taken up the fluorescein dye from the initial fluorescein instillation. Confocal microscopy of fluorescein-stained cells revealed that fluorescein was present throughout the cell cytoplasm and was retained in the cells for many hours after recovery from the corneal surface. This pilot study indicates that increased epithelial cell shedding was associated with a lens-solution combination which induces SICS. Our data provides insight into the transient nature of the SICS reaction and the nature of fluorescein staining observed in SICS.
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.
Severinsky, Boris; Wajnsztajn, Denise; Frucht-Pery, Joseph
The aim was to the evaluate performance of a novel silicone hydrogel mini-scleral contact lens (SHmS) for optical correction of keratoconus in the early stages after the corneal collagen cross-linking procedure (CXL). We retrospectively analysed the visual acuity improvement and corneal adaptation in the first 10 eyes of nine patients fitted with SHmS lenses one to 3.5 months after corneal collagen cross-linking. The lenses were designed to rest over the patients' sclera and peri-limbal cornea and vault the central cornea with minimal support over it. Visual acuities with manifest refraction and contact lenses, refractive and topographical values (Kmin and Kmax) were evaluated on lens dispensing and after six month of lens wearing. Ocular physiological responses were evaluated using the Institute of Eye Research (IER) grading scales. SHmS fitting was performed 2.1 ± 0.97 (SD) months after collagen cross-linking. Mean follow up was 10.9 ± 4.41 months (range six to 18 months). Mean decimal visual acuity with SHmS was 0.66 ± 0.22 (approximately 6/9 Snellen fraction, range 0.3 to 0.1) or 0.75 ± 0.14 (approximately 6/8.1, range 0.5 to 1.0), when omitting two amblyopic eyes. Nine (90 per cent) eyes were successfully fitted, that is, able to wear the lenses for 10 hours per day or longer. Mean wearing time was 11.7 hours (range six to 14) per day. No corneal neovascularisation or papillary reaction was found in all fitted eyes. SHmS contact lenses provide successful visual rehabilitation shortly after corneal collagen cross-linking. This new soft contact lens design with scleral fixation and minimal apical touch was demonstrated to be safe shortly after collagen cross-linking, as the avoidance of contact with the treated zone minimises contact lens influence on corneal recovery. © 2013 The Authors. Clinical and Experimental Optometry © 2013 Optometrists Association Australia.
Correa, Priscila C; Lui, Aline C F; Silva, Cely B; Gracitelli, Carolina P B; Mimica, Lycia M; Sasagawa, Suzethe M; Netto, Adamo L
To assess the antimicrobial effectiveness of multipurpose solutions in regard to the disinfection of silicone hydrogel contact lenses (CL) using a study of clinical bacterial isolates from ocular material. Three multipurpose solutions (solution A: polyhexamethylene biguanide 0.00025 g/100 mL; solution B: polyquaternary-1 0.001% and myristamidopropyl dimethylamine 0.0006%; and solution C: polyaminopropyl biguanide 0.00013% and polyquaternary 0.0001%) were used as a 3-phase disinfection on silicone hydrogel CL contaminated with bacteria from clinical isolates that were divided into five groups (group 1: Pseudomonas aeruginosa; group 2: Staphylococcus aureus; group 3: Staphylococcus epidermidis; group 4: Streptococcus spp; and group 5: enterobacteria). No differences were observed between the 24- and 48-hr measurements in any of the samples, and the positivity of microorganisms in T0 was 100% for all solutions; it was 0% in T3. Therefore, only steps T1 (rubbing followed by rinsing) and T2 (rubbing followed by rinsing and immersion of CL into solution) were considered for analysis at the 24-hr measurement time. Throughout the phases, a decrease in the number of bacteria was observed, culminating in the elimination (no recovery) of all microorganisms in the three solutions. At the end of the proposed process, the tested solutions were effective.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.
Kang, Pauline; McAlinden, Colm; Wildsoet, Christine F
To assess the effects of multifocal soft contact lenses (MF SCLs) used for myopia control on visual acuity (VA) and subjective quality of vision. Twenty-four young adult myopes had baseline high and low-contrast VAs and refractions measured and quality of vision assessed by the Quality of Vision (QoV) questionnaire with single vision SCLs. Additional VA and QoV questionnaire data were collected immediately after subjects were fitted with Proclear MF SCLs and again after a 2-week adaptation period of daily lens wear. Data were collected for two MF SCL designs, incorporating +1.50 and +3.00 D peripheral near additions, with a week washout period allowed between the two lens trials. High- and low-contrast VAs were initially reduced with both MF SCL designs, but subsequently improved to be not significantly reduced in the case of high-contrast VA by the end of the 2-week adaptation period. The quality of vision was also reduced, more so with the +3.00 D MF SCL. Quality of Vision (QoV) scores describing frequency, severity and bothersome nature of visual symptoms indicated symptoms worsening rather than resolving over the 2-week period, particularly so with the +3.00 D MF SCL. Low and high add MF SCLs adversely affected vision on initial insertion, with sustained effects on low-contrast VA and QoV scores but not high-contrast VA. Thus, high-contrast VA is not a suitable surrogate for quality of vision. In prescribing MF SCLs for myopia control, clinicians should educate patients about these effects on vision. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.
Kuryan, Jocelyn; Cheema, Anjum; Chuck, Roy S
Background 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. Objectives To assess the effects of LASEK versus LASIK for correcting myopia. Search methods 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. Selection criteria We considered only randomized controlled trials (RCTs) for the purposes of this review
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
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.
... 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 ...
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.
Ji, Qiuzhi; Yoo, Young-Sik; Alam, Hira; Yoon, Geunyoung
central vision. This trend was found to be less dominant with bifocal SCLs compared to monofocal SCL. Bifocal SCLs have a relatively small impact on myopic shift in peripheral refractive error while DoF is increased significantly. We hypothetically suggest that a mechanism underlying myopia control with these bifocal or multifocal contact lenses is an increase in DoF and a decrease in anisotropy of peripheral optical blur. © 2018 The Authors Ophthalmic & Physiological Optics © 2018 The College of Optometrists.
Jones, Lyndon; MacDougall, Nancy; Sorbara, L Gina
To compare subjective symptoms and signs in a group of individuals who wear silicone-hydrogel lenses on a daily wear basis while they sequentially used two differing care regimens. Fifty adapted soft-lens wearers were fitted with a silicone-hydrogel lens material (PureVision, Bausch & Lomb). The lenses were worn on a daily wear basis for two consecutive 1-month periods, during which the subjects used either a Polyquad (polyquaternium-1) -based system or a polyaminopropyl biguanide (PHMB) -based system, using a double-masked, randomized, crossover experimental design. Significant levels of relatively asymptomatic corneal staining were observed when subjects used the PHMB-based system, with 37% of subjects demonstrating a level of staining consistent with a classical solution-based toxicity reaction. Only 2% of the subjects exhibited such staining when using the Polyquad-based system. These results were significantly different (p < 0.001). Significant symptoms were not correlated with the degree of staining, with no differences in lens comfort or overall preference being reported between the regimens (p = NS). The only statistically significant difference in symptoms related to minor differences in stinging after lens insertion being reported, with the Polyquad-based system demonstrating less stinging (p < 0.008). Practitioners who fit silicone-hydrogel contact lenses on a daily wear basis should be wary of the potential for certain PHMB-containing multipurpose care systems to invoke corneal staining. Switching to non-PHMB based regimens will eliminate this complication in most instances.
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.
Livi, Stefano; Zeri, Fabrizio; Baroni, Rossella
To assess the compliance of Daily Disposable Contact Lenses (DDCLs) wearers with replacing lenses at a manufacturer-recommended replacement frequency. To evaluate the ability of two different Health Behavioural Theories (HBT), The Health Belief Model (HBM) and The Theory of Planned Behaviour (TPB), in predicting compliance. A multi-centre survey was conducted using a questionnaire completed anonymously by contact lens wearers during the purchase of DDCLs. Three hundred and fifty-four questionnaires were returned. The survey comprised 58.5% females and 41.5% males (mean age 34±12years). Twenty-three percent of respondents were non-compliant with manufacturer-recommended replacement frequency (re-using DDCLs at least once). The main reason for re-using DDCLs was "to save money" (35%). Predictions of compliance behaviour (past behaviour or future intentions) on the basis of the two HBT was investigated through logistic regression analysis: both TPB factors (subjective norms and perceived behavioural control) were significant (p<0.01); HBM was less predictive with only the severity (past behaviour and future intentions) and perceived benefit (only for past behaviour) as significant factors (p<0.05). Non-compliance with DDCLs replacement is widespread, affecting 1 out of 4 Italian wearers. Results from the TPB model show that the involvement of persons socially close to the wearers (subjective norms) and the improvement of the procedure of behavioural control of daily replacement (behavioural control) are of paramount importance in improving compliance. With reference to the HBM, it is important to warn DDCLs wearers of the severity of a contact-lens-related eye infection, and to underline the possibility of its prevention. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Szczotka-Flynn, Loretta B; Debanne, Sara; Benetz, Beth Ann; Wilson, Tawnya; Brennan, Noel
This study hypothesized that a traditional high-water contact lens of moderate oxygen transmissibility (Dk/t) is noninferior to common silicone hydrogel (SH) lenses worn for daily wear with respect to measures of hypoxic stress. Thirty-six habitual contact lens wearers completed wear of three lens types worn in a randomized order: etafilcon A (ACUVUE 2, control), lotrafilcon B (Air Optix Aqua), and comfilcon A (Biofinity). Central corneal thickness (CT) and limbal hyperemia were measured >2 hr after waking and after 6 to 8 hr of wear on days 1 and 7. Endothelial bleb formation was measured on day 1 of each lens type. Noninferiority of etafilcon A, with respect to the other two lens types, was assumed if the following difference margins of equivalence were met: <1.5% for corneal swelling, <0.5 grade for limbal hyperemia, and <1% area of endothelial blebs. Outcomes were modeled using generalized linear mixed modeling techniques. All lenses showed reductions in least-square mean estimates of CT on both days: etafilcon A -0.26% at day 1 and -0.31% at day 7; lotrafilcon B -1.11% at day 1 and -1.06% at day 7; comfilcon A -0.63% at day 1 and -0.84% at day 7. The difference in mean swelling between etafilcon A and lotrafilcon B was 0.85% at day 1 (95% confidence interval [0.4%-1.3%]) and 0.75% at day 7 (0.3%-1.2%). The difference in mean swelling between etafilcon A and comfilcon A was 0.37% at day 1 (-0.1% to 0.8%) and 0.53% at day 7 (0.1%-1.0%). For limbal redness, etafilcon A fell within 0.1 grade of lotrafilcon B and 0.18 grade of comfilcon A. For endothelial bleb formation, etafilcon A fell within 0.45% of lotrafilcon B and 0.23% of comfilcon A. The etafilcon A control lens resulted in corneal deswelling throughout the day as did the SH lens types. Limbal hyperemia and endothelial bleb formation with all lenses were negligible, and noninferiority assumptions were met between the lens types for all outcomes. Equivalence of etafilcon A with respect to the two SH lenses
Faghri, Jamshid; Razavi, Mohamad Reza
Disposable soft contact lenses that are commonly used after laser refractive surgery are known to be colonized by bacteria and play a key role in Bacterial Keraitis (BK) pathogenesis. Coagulase-negative staphylococci (CoNS) have been found to be the most common pathogen involved in this postoperative infection. In this study a rapid and a simple assay was developed for studying attachment and accumulation of CoNS on soft contact lenses in vitro using [3H] thymidine. Thirty-five isolates of CoNS were obtained from 27 laser refractive surgery patients. Twenty-five of these thirty-five CoNS were isolated in multiple cultures. Ten CoNS were isolated in cultures from patients who underwent reoperation. The assay was optimized using a biofilm-producing strain, S. epidermidis RP62A, which was subcultured overnight at 37 degrees C on blood agar medium. Quantitative determination of biofilm production was tested. Presence of the genes icaADB and icaD was determined in all isolates. All isolates were biochemically analyzed using the Phene Plate (PhP) system modified for typing of CoNS. The CoNS isolates were further characterized to species level using ID32Staph.Mann-Whitney rank sum test and chi-square test were used to identify statistical differences in adherence, index, antibiotic susceptibility patterns, and biofilm production or presence of the ica operon between clinically significant isolates and non-postoperative BK isolates. No differences in attachment and accumulation were found between isolates causing BK after laser refractive surgery and contaminant isolates. In addition, there were no differences in the distribution of the ica operon between the two groups, as determined by polymerase chain reaction. Nevertheless, the ability to produce biofilm was found to be present significantly more frequently among BK isolates than among non-postoperative BK isolates. This study shows that the method using radioactive thymidine to analyze adherence of CoNS to soft
Danion, Anne; Doillon, Charles J; Giasson, Claude J; Djouahra, Saliha; Sauvageau, Patrick; Paradis, Renée; Vermette, Patrick
To validate the biocompatibility and transmittance properties of contact lenses bearing intact liposomes. These liposomal lenses loaded with therapeutics can be used as ophthalmic drug delivery systems. The biocompatibility of soft contact lenses, coated with liposomes was evaluated through in vitro direct and indirect cytocompatibility assays on human corneal epithelial cells, on reconstructed human corneas and on ex vivo rabbit corneas. The direct and indirect transmission spectra of liposome-covered lenses were also evaluated to test if they transmit all wavelengths of the ultraviolet-visible spectrum, to thereby fulfill their optical function, without gross alteration of the colors perception and with a minimum of light dispersion. Contact lenses bearing layers of stable liposomes did not induce any significant changes in cell viability and in cell growth, compared with lenses bearing no liposome. Elution assays revealed that no cytotoxic compound leaks from the lenses whether bearing liposomes or not. Histological analyses of reconstructed human corneas and ex vivo rabbit corneas directly exposed to liposomal lenses revealed neither alteration to the cell nor to the tissue structures. Contact lenses bearing layers of liposomes did not significantly affect light transmission compared with control lenses without liposome at the wavelength of maximal photopic sensitivity, i.e., 550 nm. In addition, the contact lenses afford more eye protection in the ultraviolet spectrum, compared with the control lenses. Liposomal contact lenses are biocompatible and their transmittance properties are not affected in the visible light range.
Holden, B A; Reddy, M K; Sankaridurg, P R; Buddi, R; Sharma, S; Willcox, M D; Sweeney, D F; Rao, G N
Contact lens-induced peripheral ulcer (CLPU), a sudden-onset adverse event observed with extended wear of hydrogel lenses, is characterized by a single, small, circular, focal anterior stromal infiltrate in the corneal periphery or midperiphery. The condition is always associated with a significant overlying epithelial loss and resolves in a scar. The aim was to determine, by using histopathologic techniques, the nature and type of the corneal infiltrate of these events. Three CLPUs observed in three patients using disposable hydrogel lenses on an extended-wear schedule were examined. The eye was topically anesthetized, and a corneal section including all of the infiltrate was taken. A small triangular piece of conjunctiva immediately adjacent to the infiltrate was sectioned. The tissue was immediately fixed, processed, stained using hematoxylin and eosin and periodic acid-Schiff stains, and examined by using light microscopy. The diameter of these three corneal infiltrates varied from 0.3 to 0.6 mm. Histopathology of the corneal sections revealed a focal epithelial loss corresponding to the infiltrated stroma in all three patients. The adjacent epithelium was thinned. Bowman's layer was intact in two patients and had a localized area of loss in the remaining patient. The anterior stroma was densely infiltrated with polymorphonuclear leukocytes and had focal areas of necrosis. The infiltration was most dense in the region immediately underlying Bowman's layer. No other infiltrative cell type was seen in any of the sections. Histopathology of the conjunctiva revealed features consistent with normal conjunctival tissue. On histopathology of CLPU, distinctive features (i.e., focal corneal epithelial loss, an intact Bowman's membrane, and a localized infiltration of the anterior stroma with polymorphonuclear leukocytes) were seen. These features suggest that the event is an acute inflammatory process and probably noninfective in nature.
Tran, H V; Eperon, S; Guex-Crosier, Y
Eotaxin-1 (CCL11) is a potent eosinophil chemotactic and activating peptide that may be implicated in the pathogenesis of chronic allergic eye disease and has been associated with the wearing of contact lenses (CL) in patients with contact lens papillary conjunctivitis (CLPC). The purpose of this study was to study eotaxin-1 expression in the tears of long-term CL wearers. Tears were collected with glass capillaries from 15 patients (2 male, 13 female) with various degree of CLPC at 2-year intervals. CLPC severity was graded from 0 to 4 with reference to standard slit-lamp photographs of the superior tarsal conjunctiva. The eotaxin-1 level in the tears was measured by an ELISA, using mouse anti-human eotaxin monoclonal antibodies. The mean age was 32.5 ± 13.3 years (range: 17 - 69 years). The mean interval between the tear collections was 30 ± 4.8 months. The mean concentration of eotaxin was 2150 ± 477 pg/mL and 2486 ± 810 pg/mL for the first and second series, respectively. The difference was not statistically significant (paired Wilcoxon/Kruskal-Wallis, p = 0.803). The mean score of papilla grade was 1.26 ± 0.18 for the first sample and 1.40 ± 0.19 two years later. There was no significant difference of grading between the two time periods (paired Wilcoxon/Kruskal-Wallis, p = 0.751). the eotaxin-1 level remains up-regulated over a long time period in patients wearing CL, most of them with chronic CLPC. Eotaxin may play a role in the pathogenesis of contact lens intolerance. © Georg Thieme Verlag KG Stuttgart · New York.
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.
Background Pseudomonas aeruginosa is commonly associated with contact lens (CL) -related eye infections, for which bacterial adhesion and biofilm formation upon hydrogel CLs is a specific risk factor. Whilst P. aeruginosa has been widely used as a model organism for initial biofilm formation on CLs, in-vitro models that closely reproduce in-vivo conditions have rarely been presented. Results In the current investigation, a novel in-vitro biofilm model for studying the adherence of P. aeruginosa to hydrogel CLs was established. Nutritional and interfacial conditions similar to those in the eye of a CL wearer were created through the involvement of a solid:liquid and a solid:air interface, shear forces and a complex artificial tear fluid. Bioburdens varied depending on the CL material and biofilm maturation occurred after 72 h incubation. Whilst a range of biofilm morphologies were visualised including dispersed and adherent bacterial cells, aggregates and colonies embedded in extracellular polymer substances (EPS), EPS fibres, mushroom-like formations, and crystalline structures, a compact and heterogeneous biofilm morphology predominated on all CL materials. Conclusions In order to better understand the process of biofilm formation on CLs and to test the efficacy of CL care solutions, representative in-vitro biofilm models are required. Here, we present a three-phase biofilm model that simulates the environment in the eye of a CL wearer and thus generates biofilms which resemble those commonly observed in-situ. PMID:21062489
Cardona, Genís; López, Sílvia
To determine working distance, pupil diameter and illumination in real life conditions in a sample of presbyopic participants performing habitual tasks. A total of 59 presbyopic subjects (aged between 45 and 63 years) with different occupational backgrounds participated in the study. Participants were first interviewed regarding their habitual tasks with the aid of an ad hoc questionnaire, following which in-office photopic and mesopic pupil diameter was determined. Pupil diameter was also evaluated while participants conducted each of the self-reported habitual tasks by taking a photograph, which was later submitted to image analysis. In addition, working distance was determined with a measuring tape and the illumination that reached the pupil during each of the different tasks was measured, in lux, with a light meter. The four most common habitual tasks were computer use, reading, sewing and sports. A high intersubject variability was found in pupil diameter, working distance and illumination conditions while conducting the same task. Statistically significant differences were found between the in-office measured photopic and mesopic pupil diameters and those obtained while participants were conducting their habitual tasks in real life conditions (all p<0.001). Potential multifocal contact lens users may present with different ages, different jobs or hobbies and different preferences regarding lighting conditions and working distances. This results in different pupil size, even within the same task. This information may be critical when selecting a particular lens design and add power. Eye care practitioners are therefore advised to assess pupil diameter in real life conditions. Copyright © 2015 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.
Zhang, Jing; Zhou, Yue-Hua; Li, Rui; Tian, Lei
AIM To compare visual performance of wavefront-guided laser in situ keratomileusis (LASIK) with iris-registration (Wg-LASIK group) and conventional LASIK (LASIK group) one year after surgery and analyze the correlation between wavefront aberrations and visual performance. METHODS Eight hundred and fifty-two myopic eyes of 430 patients were enrolled in this prospective study and divided into two groups: Wg-LASIK group (436 eyes) and LASIK group (416 eyes). A Wavescan Wavefront aberrometer was used to analyze Zernike coefficients and the root-mean-square (RMS) of higher order aberrations, and Optec 6500 visual function instrument was used to measure contrast sensitivity (CS) before and 3, 6, 12 months after surgery. RESULTS The mean spherical equivalent (SE) in Wg-LASIK group was significantly better than those in LASIK group one year after surgery (P=0.024). Wg-LASIK eyes showed better CS values than LASIK eyes at all spatial frequencies with and without glare after surgery (P all<0.01). Moreover, the increase of higher RMS (RMSh), coma, RMS3, RMS4, RMS5 in Wg-LASIK group were significantly lower than those in LASIK group 1 year after surgery (P all<0.05). The increase of coma, spherical aberration (SA), RMS3 and RMS4 in Wg-LASIK and coma and RMS3 in LASIK group were negatively correlated with reduction of contrast sensitivity 1 year after surgery. CONCLUSION A significant better visual performance is got in Wg-LASIK group compared with LASIK group 1 year after surgery, and the Wg-LASIK is particularly suitable for eyes with high-magnitude RMSh. PMID:23991386
... whether LASIK would be appropriate for you are: • dry eye syndrome . If dry eye is left untreated prior to surgery, patients may be disappointed with their LASIK results. If dry eye is diagnosed and adequately treated before surgery, you ...
... your prescription expires Lens measurements The contact lens brand name and material Your doctor’s name and contact ... mail-order sellers may send you a different brand. Contact lenses may look the same, but materials ...
Li, Jinyang; Zhang, Xiahua; Zheng, Qinxiang; Zhu, Yirui; Wang, Hui; Ma, Huixiang; Jhanji, Vishal; Chen, Wei
To comparatively evaluate the efficacy of a bandage contact lens (BCL) and autologous serum (AS) eye drops in the management of severe dry eye caused by Sjögren syndrome (SS). In this prospective randomized study, 40 patients with SS were enrolled. Patients were divided into 2 treatment groups: BCL and AS. A total of 37 patients were included, 18 patients (35 eyes) in the AS group and 19 patients (36 eyes) in the BCL group. At the end of 6 weeks, the best-corrected visual acuity improved significantly in the BCL group (0.5 ± 0.3 vs. 0.3 ± 0.2, P = 0.003) but not in the AS group (0.4 ± 0.3 vs. 0.3 ± 0.3, P = 0.11). The best-corrected visual acuity remained stable up to 6 weeks after discontinuation of the BCL (0.5 ± 0.3 vs. 0.4 ± 0.2, P = 0.03). Although the Ocular Surface Disease Index scores decreased significantly after treatment in both groups, patients in the BCL group had lower Ocular Surface Disease Index scores than those in the AS group (53.4 vs. 41.8 at week 3, 47.1 vs. 31.0 at week 6, 52.7 vs. 32.0 at week 12; P = 0.014, <0.001, <0.004, respectively). The "faces" scores showed improved quality of life in both groups. Tear break-up time improved significantly in both groups except at 6 weeks after discontinuation of the AS. Patients in the BCL group had lower corneal staining scores than those of the AS group after 6 weeks of treatment and 6 weeks after discontinuation of treatment (P < 0.01). There was no significant change in Schirmer I test scores between or within groups. Balafilcon A silicone hydrogel contact lenses as a BCL were effective in the management of SS-associated dry eye. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT02147509.
... Plastic Surgery Center Laser Surgery Education Center Redmond Ethics Center Global Ophthalmology Guide Academy Publications EyeNet Ophthalmology ... Plastic Surgery Center Laser Surgery Education Center Redmond Ethics Center Global Ophthalmology Guide Find an Ophthalmologist Advanced ...
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.
Tilia, Daniel; Munro, Anna; Chung, Jiyoon; Sha, Jennifer; Delaney, Shona; Kho, Danny; Thomas, Varghese; Ehrmann, Klaus; Bakaraju, Ravi Chandra
To compare the visual performance of prototype contact lenses which extend depth-of-focus (EDOF) by deliberate manipulation of multiple higher-order spherical aberration terms and a commercially-available center-near lens (AIR OPTIX Aqua Multifocal, AOMF). This was a prospective, cross-over, randomized, single-masked (participant), short-term clinical trial where 52 participants (age 45-70 years) were stratified as low, medium or high presbyopes and wore EDOF and AOMF on different days. Objective measures comprised high and low contrast visual acuity (HCVA/LCVA, logMAR), and contrast sensitivity (log units) at 6m; HCVA at 70cm, 50cm and 40cm and stereopsis (seconds of arc) at 40cm. HCVA at 70cm, 50cm and 40cm were measured as "comfortable acuity" rather than conventional resolution acuity. Subjective measures comprised clarity-of-vision and ghosting at distance, intermediate and near, overall vision satisfaction and ocular comfort (1-10 numeric rating scale) and lens purchase (yes/no response). Statistical analysis included repeated measures ANOVA, paired t-tests and McNemar's test. Significant differences between lens types were independent of strata (p≥0.119). EDOF was significantly better than AOMF for HCVA at 40cm (0.42±0.18 vs. 0.48±0.22, p=0.024), stereopsis (98±88 vs. 141±114, p<0.001), clarity-of-vision at intermediate (8.5±1.6 vs. 7.7±1.9, p=0.006) and near (7.3±2.5 vs. 6.2±2.5, p=0.005), lack-of-ghosting (p=0.012), overall vision satisfaction (7.5±1.7 vs. 6.4±2.2, p<0.001) and ocular comfort (9.0±1.0 vs. 8.3±1.7, p=0.002). Significantly more participants chose to only-purchase EDOF (33% vs. 6%, p=0.003).). There were no significant differences between lens types for any objective measure at 6m or clarity-of-vision at distance (p≥0.356). EDOF provides better intermediate and near vision performance in presbyopes than AOMF with no difference for distance vision during short-term wear. Copyright © 2016 Spanish General Council of Optometry
Brennan, Noel A; Coles, M-L Chantal; Connor, Heather R M; McIlroy, Robert G
To evaluate the clinical performance of comfilcon A (Biofinity) during 12 months of continuous wear compared to other silicone-hydrogel lenses. Forty-five subjects were fitted in one eye with the comfilcon A (test) lens. For 22 subjects, the other eye was fitted with lotrafilcon A (group A) and for the remaining 23 subjects the other eye was fitted with balafilcon A (group B). Twelve-month data are presented on 48 measured variables. There were no serious adverse events during the course of the study. A total of 33 subjects completed the study, with only 4 discontinuations for lens-related reasons, spread proportionately between the lenses. On preference scales, the test lens was superior to both control lenses for comfort (p<0.05) and overall preference (p<0.05) and in group A for vision (p<0.05). On grading scales, the test lens scored better than both control lenses for overall comfort (p<0.1 for group A, p<0.05 for group B), comfort during the day (p<0.05), end-of-day comfort (p<0.05) and overall preference (p<0.05), and better in group A for general vision quality (p<0.01), night vision quality (p<0.01) and handling (p<0.05). All lenses performed to a comparable degree on the basis of microcysts and corneal staining. There were significant differences between lenses in producing limbal redness (p<0.05), bulbar conjunctival hyperemia (p<0.1) and conjunctival NaFl staining (p<0.01) with the control lens in group A showing the greatest effect and the control lens in group B the least. Comfilcon A offers performance advantages over first generation silicone-hydrogel materials for continuous wear.
Kovoor, Timmy A; Mohamed, Engy; Cavanagh, H Dwight; Bowman, R Wayne
To evaluate the safety and efficacy of excimer laser refractive surgery in correcting refractive error in eyes that have undergone previous penetrating keratoplasty (PK). Twenty-three keratorefractive procedures on 16 eyes from 16 consecutive subjects were evaluated between 2002 and 2008. Each patient presented a previous history of a PK with subsequent postoperative myopia and astigmatism. Keratometric value, manifest refraction, best-corrected visual acuity, uncorrected visual acuity, and complications were determined. There were a total of 14 photorefractive keratectomy (PRK) procedures performed on 11 eyes and 9 laser in situ keratomileusis (LASIK) procedures performed on 5 eyes. In the PRK group, the preoperative post-PK manifest refractive spherical equivalent and cylindrical error were -6.22 +/- 6.23 diopter and 5.23 +/- 2.26 D, respectively. The PRK postoperative manifest refractive spherical equivalent and cylindrical error were -3.61 +/- 4.23 D (P=0.25) and 3.21 +/- 1.78 D (P=0.02), respectively. In the LASIK group, the preoperative post-PK manifest refractive spherical equivalent and cylindrical error were -3.05 +/- 3.29 D and 4.11 +/- 2.38 D, respectively. The LASIK postoperative manifest refractive spherical equivalent and cylindrical error were -1.51 +/- 2.02 D (P=0.24) and 2.08 +/- 1.26 D (P=0.03), respectively. There was a 2-line or greater improvement of uncorrected visual acuity in 8 of the 14 PRK treatments and 5 of the 9 LASIK treatments. There were two episodes of acute graft rejection. One of the episodes resolved with topical and oral corticosteroids, and the other episode required a repeat corneal transplantation. PRK and LASIK are effective tools in reducing surgically induced astigmatism after penetrating corneal transplantation in most patients in this case series. The reduction of astigmatism may allow improved contact lens or spectacle fitting to achieve best-corrected binocular visual acuity.
Randleman, J Bradley; Su, Johnny P; Scarcelli, Giuliano
To evaluate the biomechanical changes occurring after LASIK flap creation and rapid corneal cross-linking (CXL) measured with Brillouin light microscopy. Porcine eyes (n = 11) were evaluated by Brillouin light microscopy sequentially in the following order: virgin state, after LASIK flap creation, and after rapid CXL. Each eye served as its own control. Depth profile of the Brillouin frequency shift was computed to reveal the depth-dependent changes in corneal stiffness. There was a statistically significant reduction of Brillouin shift (reduced corneal stiffness) after LASIK flap creation compared to virgin corneas across total corneal thickness (-0.035 GHz, P = .0195) and within the anterior stromal region (-0.104 GHz, P = .0039). Changes in the central (-0.029 GHz, P = .0391) and posterior (-0.005 GHz, P = .99) stromal regions were not significant. There was a small increase in Brillouin shift after rapid cross-linking that was not statistically or clinically significant across total corneal thickness (0.006 GHz, P = .4688 for any specific stromal region; 0.002 to 0.009 GHz, P > .46 for all). LASIK flap creation significantly reduced Brillouin shift in the anterior third of the stroma in porcine eyes. Rapid corneal cross-linking had no significant effect on Brillouin shift after LASIK flap creation in porcine eyes. With further validation, non-contact, non-perturbative Brillouin microscopy could become a useful monitoring tool to evaluate the biomechanical impact of corneal refractive procedures and corneal cross-linking protocols. [J Refract Surg. 2017;33(6):408-414.]. Copyright 2017, SLACK Incorporated.
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, 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
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.
Carpel, E F; Carlson, K H; Shannon, S
To present an example of a pattern of lines resembling fine lattice on the corneal surface subsequent to laser in situ keratomileusis (LASIK). This subtle phenomenon may be relatively common and may affect visual outcome. Case report. A 41-year-old year old man with high myopia and best-corrected visual acuity of 20/20 +2 in each eye underwent laser in situ keratomileusis (LASIK). No operative or postoperative complications occurred. No striae were evident on slit-lamp examination with direct illumination and retroillumination at the time of surgery or in the postoperative period. Postoperative uncorrected visual acuity was 20/25 with a best-corrected spectacle correction of 20/25 in both eyes. Fine lines in a lattice pattern were seen only with fluorescein dye in the precorneal tear film as areas of "negative stain" within the LASIK flap. With tear film supplementation, the lines were less evident and visual acuity improved. One year postoperatively, his uncorrected visual acuity was 20/25 in both eyes. The best-corrected spectacle visual acuity was RE: 20/20 -2, LE: 20/25. The fine lines were still present within the flap. A soft contact lens improved visual acuity to 20/20 in both eyes. Although all four puncta were occluded, he had no epiphora. Fine lines in a lattice pattern that may represent folds in the epithelium or Bowman layer may be present within the flap after LASIK and may adversely affect visual acuity. They may be visible as areas of negative stain with fluorescein dye in the precorneal tear film in the absence of any striae visible in the flap. These superficial lines have been seen more in patients with high degrees of correction and in patients with dry eye. If visual acuity is affected, it may be improved with punctal occlusion, tear supplements, or a contact lens.
Bueno, Juan M.; Berrio, Esther; Artal, Pablo
Imaging polarimetry provides spatially resolved information on the polarization properties of a system. In the case of the living human eye, polarization could be related to the corneal biomechanical properties, which vary from the normal state as a result of surgery or pathologies. We have used an aberro-polariscope, which we recently developed, to determine and to compare the spatially resolved maps of polarization parameters across the pupil between normal healthy and post-LASIK eyes. The depolarization distribution is not uniform across the pupil, with post-surgery eyes presenting larger levels of depolarization. While retardation increases along the radius in normal eyes, this pattern becomes irregular after LASIK refractive surgery. The maps of slow axis also differ in normal and post-surgery eyes, with a larger disorder in post-LASIK eyes. Since these changes in polarization indicate subtle structural modifications of the cornea, this approach can be useful in a clinical environment to follow the biomechanical and optical changes of the cornea after refractive surgery or for the early diagnosis of different corneal pathologies.
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 ofmore » the entire universe, including the otherwise-invisible dark matter.« less
Freeman, J Christopher; Chuck, Roy S
With baby boomers aging, and despite a growing global population, there is a decreasing number of potential laser vision correction patients. Some believe that the worldwide economic downturn of these times will limit the number of potential patients as well. This article highlights looking to an alternative segment of the population to identify potential laser vision correction patients and the limitations of reaching this group. The group known as generation Y contains a large number of individuals who may be candidates for laser vision correction. Traditional marketing efforts present challenges in reaching this particular population segment. Many individuals in this group are already patients of eye doctors for contact lenses and glasses and can be reached by these eye doctors to address candidacy and education of laser vision correction. Generation Y represents a large population segment that contains technology-embracing individuals who, although hard to reach with traditional marketing efforts, may be reached by fellow eye doctors already managing these patients. There are many in this age group who would be good laser vision correction candidates.
Lazaridis, Apostolos; Reinstein, Dan Z; Archer, Timothy J; Schulze, Stephan; Sekundo, Walter
To design a technique for intrastromal transplantation of stromal lenticules with specific refractive power for correction of post-LASIK induced hyperopia and astigmatism. A 28-year-old patient was referred for consultation after complicated LASIK for moderate myopia and astigmatism. The refractive error of the right eye was severely overcorrected due to data entry error. Post-LASIK refraction showed high astigmatism (right eye: +6.50 -9.00 @ 84°) and corrected distance visual acuity (CDVA) of 20/32. The corneal thickness was 282 µm. A refractive lenticule transplantation was performed due to contact lens intolerance, poor visual acuity, and severe anisometropia. A toric and myopic lenticule, obtained from a donor using the femtosecond lenticule extraction technique, was implanted under the flap to reduce the refractive error, bring the refraction of the eye to the level correctable by phakic intraocular lens, and restore corneal volume. Six weeks postoperatively, the donor lenticule was spread smoothly in the interface with a minor temporal decentration in relation to pupil center. The refraction showed a reduction of astigmatism but a stronger myopization compared to preoperative calculations (right eye: -6.50 -4.00 @ 70°). At 3 months, the CDVA returned to the preoperative value of 20/32. One year postoperatively, corneal tomography showed no signs of ectasia and biomicroscopy revealed no signs of rejection. After implanting a toric myopic implantable collamer lens, the patient regained uncorrected distance visual acuity of 20/40 and full stereopsis. The refractive lenticule transplantation technique offers a solution for rare cases of post-LASIK hyperopia and high astigmatism while restoring the volume of thin corneas. Moreover, it is a reversible procedure with low probability of rejection. [J Refract Surg. 2016;32(11):780-786.]. Copyright 2016, SLACK Incorporated.
Katz, Toam; Wagenfeld, Lars; Galambos, Peter; Darrelmann, Benedikt Große; Richard, Gisbert; Linke, Stephan Johannes
To compare the efficacy, safety, predictability, and vector analysis indices of LASIK and photorefractive keratectomy (PRK) for correction of high cylinder of greater than 3 diopters (D) in myopic eyes. The efficacy, safety, and predictability of LASIK or PRK performed in 114 consecutive randomly selected myopic eyes with an astigmatism of greater than 3 D were retrospectively analyzed at the 2- to 6-month follow-up visits. Vector analysis of the cylindrical correction was compared between the treatment groups. A total of 57 eyes receiving PRK and 57 eyes receiving LASIK of 114 refractive surgery candidates were enrolled in the study. No statistically significant difference in efficacy [efficacy index = 0.76 (±0.32) for PRK vs 0.74 (±0.19) for LASIK (P = .82)], safety [safety index = 1.10 (±0.26) for PRK vs 1.01 (±0.17) for LASIK (P = .121)], or predictability [achieved astigmatism < 1 D in 39% of PRK- and 54% of LASIK-treated eyes, and < 2 D in 88% of PRK- and 89% of LASIK-treated eyes (P = .218)] was demonstrated. Using Alpins vector analysis, the surgically induced astigmatism and difference vector were not significantly different between the surgery methods, whereas the correction index showed a slight and significant advantage of LASIK over PRK (1.25 for PRK and 1.06 for LASIK, P < .001). LASIK and PRK are comparably safe, effective, and predictable procedures for excimer laser correction of high astigmatism of greater than 3 D in myopic eyes. Predictability of the correction of the cylindrical component is lower than that of the spherical equivalent. Copyright 2013, SLACK Incorporated.
... 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 ...
Choo, Jennifer D; Holden, Brien A; Papas, Eric B; Willcox, Mark D P
To determine whether contact lenses designed for orthokeratology (OK) are colonized by greater numbers of bacteria compared with standard (alignment fitted) design rigid gas permeable lenses before and after lens wear. Eighteen 1-year-old cats were randomly fitted with an OK lens in one eye and an alignment fitted (AF) lens in the other eye. Both lenses were made in the same diameter and central thickness and of the same material. Two separate wearing periods of 2 weeks and 6 weeks were used. After each wearing period, lenses were soaked in Pseudomonas aeruginosa (6294 or 6206) for 10 min. The lenses were then reinserted onto their respective corneas for a wearing period of 16 hours after which lenses were collected and remaining adhered bacteria quantified. Unworn control lenses were also soaked and bacteria enumerated for comparison. There were no significant differences in the number of bacteria adherent to unworn AF and OK lenses. Analysis of lenses after wear showed OK lenses retained significantly higher numbers of viable bacteria than AF lenses in all studies. OK lenses retain more bacteria than AF rigid gas permeable lenses after bacteria-loaded overnight lens wear. This may increase the risk for an infection in OK patients should suitable conditions be present. Specific education on the cleaning of OK lenses is essential.
Dutta, Debarun; Ozkan, Jerome; Willcox, Mark D P
Covalent immobilization of antimicrobial peptide melimine onto contact lenses can produce broad-spectrum antimicrobial lenses. The purpose of this study was to investigate the performance of melimine-coated contact lenses in an animal model and human clinical trial. Melimine was covalently attached onto the surface of contact lenses via EDC (1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride) coupling. A rabbit model of daily contralateral wear of lenses for 22 days was conducted to assess the lens safety. A prospective, randomized, double-masked, one-day human clinical trial was used to evaluate subjective responses and ocular physiology during contralateral wear of melimine-coated (test) and uncoated (control) lenses. Delayed reactions were monitored during follow-up visits after 1 and 4 weeks. Ex vivo retention of antimicrobial activity of worn lenses was assessed by reduction in numbers of viable Pseudomonas aeruginosa and Staphylococcus aureus. Melimine-coated lenses produced no ocular signs or symptoms that would indicate cytotoxicity during the lens wear of rabbits. No histological changes were found in rabbit corneas. During the human trial, no differences were observed in wettability, surface deposition, lens-fitting centration, movement, tightness, and corneal coverage between test and control lenses (p > 0.05). There were no significant differences in bulbar, limbal, or palpebral redness or conjunctival staining (p > 0.05). Mean corneal (extent, depth, and type) staining was higher for test lenses compared with that for control lenses (p < 0.05). There was no significant difference in subjective responses for lens comfort, dryness, and awareness (p > 0.05). No delayed reactions were associated with the test lenses. Worn test lenses retained more than 1.5 log inhibition against both bacterial types. Melimine-coated contact lenses were worn safely by humans. However, they were associated with higher corneal staining. The melimine-coated lenses
Osman, Essam A.; Alsaleh, Ahmed A.; Al Turki, Turki; AL Obeidan, Saleh A.
Acute angle closure glaucoma is unexpected complication following laser in situ keratomileusis (LASIK). We are reporting a 49-years-old lady that was presented to the emergency department with acute glaucoma in both eyes soon after LASIK correction. Diagnosis was made on detailed clinical history and examination, slit lamp examination, intraocular pressure measurement and gonioscopy. Laser iridotomy in both eyes succeeded in controlling the attack and normalizing the intraocular pressure (IOP) more than 6 months of follow-up. Prophylactic laser iridotomy is essential for narrow angle patients before LASIK surgery if refractive laser surgery is indicated. PMID:23960863
To study the advantage of active eye-tracking for photorefractive surgery. In a prospective, double-masked study, LASIK for myopia and myopic astigmatism was performed in 50 patients using the ALLEGRETTO WAVE version 1007. All patients received LASIK with full comprehension of the importance of fixation during the procedure. All surgical procedures were performed by a single surgeon. The eye-tracker was turned off in one group (n = 25) and kept on in another group (n = 25). Preoperatively and 3 months postoperatively, patients underwent a standard ophthalmic examination, which included comeal topography. In the patients treated with the eye-tracker off, all had uncorrected visual acuity (UCVA) of > or = 20/40 and 64% had > or = 20/20. Compared with the patients treated with the eye-tracker on, they had higher residual cylindrical astigmatism (P < .05). Those treated with the eye-tracker on achieved better UCVA and best spectacle-corrected visual acuity (P < .05). Spherical error and potential visual acuity (TMS-II) were not significantly different between the groups. The flying-spot system can achieve a fair result without active eye-tracking, but active eye-tracking helps improve the visual outcome and reduces postoperative cylindrical astigmatism.
Study on Prevalence, Antibiotic Susceptibility, and tuf Gene Sequence-Based Genotyping of Species-Level of Coagulase-Negative Staphylococcus Isolated From Keratitis Caused by Using Soft Contact Lenses.
Faghri, Jamshid; Zandi, Alireza; Peiman, Alireza; Fazeli, Hossein; Esfahani, Bahram Nasr; Safaei, Hajieh Ghasemian; Hosseini, Nafiseh Sadat; Mobasherizadeh, Sina; Sedighi, Mansour; Burbur, Samaneh; Oryan, Golfam
To study on antibiotic susceptibility and identify coagulase-negative Staphylococcus (CoNS) species based on tuf gene sequencing from keratitis followed by using soft contact lenses in Isfahan, Iran, 2013. This study examined 77 keratitis cases. The samples were cultured and the isolation of CoNS was done by phenotypic tests, and in vitro sensitivity testing was done by Kirby-Bauer disk diffusion susceptibility method. Thirty-eight of isolates were conveniently identified as CoNS. In this study, 27 (71.1%), 21 (55.3%), and 16 (42.1%) were resistant to penicillin, erythromycin, and tetracycline, respectively. One hundred percent of isolates were sensitive to gentamicin, and 36 (94.7%) and 33 (86.8%) of isolates were sensitive to chloramphenicol and ciprofloxacin, respectively. Also, resistances to cefoxitin were 7 (18.4%). Analysis of tuf gene proved to be discriminative and sensitive in which all the isolates were identified with 99.0% similarity to reference strains, and Staphylococcus epidermidis had the highest prevalence among other species. Results of this study showed that CoNS are the most common agents causing contact lens-associated microbial keratitis, and the tuf gene sequencing analysis is a reliable method for distinguishing CoNS species. Also gentamycin, chloramphenicol, and ciprofloxacin are more effective than the other antibacterial agents against these types of bacteria.
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.
Willcox, Mark D P
During wear of contact lenses on a daily wear basis, it is necessary to disinfect the lens overnight before reinserting the lens the next day. The ability of the solutions used for this to disinfect lenses and lens cases is important for safe lens wear. The literature on the disinfecting ability of multipurpose disinfecting solutions (MPDS) commonly used with silicone hydrogel lenses reported during the period 2000 to 2012 is reviewed, as this is the period of time during which these lenses have been commercially available. Particular emphasis is placed on the ability of disinfecting solutions to control colonization of lens cases by microbes and changes in composition and use of the solutions. In addition, the literature is reviewed on ways of minimizing lens case microbial contamination. Maintaining the hygiene of contact lenses and lens cases is important in minimizing various forms of corneal infiltrative events that occur during lens wear. Although lens case contamination is not associated with different lenses, it is determined by use of different MPDS. MPDS that allow more frequent or heavy contamination of cases by Gram-negative bacteria are associated with a higher incidence of corneal infiltrative events. MPDS are now available that contain dual disinfectants. Wiping lens cases with tissues or using lens cases that incorporate silver are associated with reductions in contamination in clinical trials. Similarly, using MPDS to rub and rinse lenses before disinfection may reduce levels of microbes on lenses. The MPDS also contain surfactants that help reduce deposition and denaturation of proteins on lenses. Improvements in MPDS formulations and hygiene practices may help to reduce the incidence of adverse events that are seen during use with silicone hydrogel lenses.
Lee, Bryan S; Gupta, Preeya K; Davis, Elizabeth A; Hardten, David R
To report the outcomes of photorefractive keratectomy (PRK) enhancement after LASIK for patients diagnosed as having hyperopic and myopic refractive errors. In this retrospective case series at a single private practice in the United States, all patients undergoing PRK enhancement after LASIK were identified. Patients with visually significant cataract, non-plano targets, and follow-up of fewer than 226 days were excluded. The primary outcome measure was uncorrected distance visual acuity (UDVA) with secondary measures of corrected distance visual acuity (CDVA) and postoperative refractive error. Linear regression analysis was performed for actual versus targeted change in spherical equivalent. Mean UDVA improved from 20/39 to 20/24 for hyperopes (n = 14; P < .002) and from 20/45 to 20/22 for myopes (n = 29; P < .0000001) after enhancement. All patients had a UDVA of 20/40 or better at their most recent follow-up visit. Fifty percent of hyperopes and 65.5% of myopes were 20/20 or better. The mean refractive error for hyperopes changed from +1.10 ± 0.71 (range: +0.13 to +2.25 diopters [D]) to +0.38 ± 0.66 D (range: -0.75 to +1.38 D) and from -1.21 ± 0.61 (range: -3.25 to -0.38 D) to +0.34 ± 0.45 D (range: -0.25 to +1.75 D) for myopes. The manifest refraction cylinder decreased from 0.84 to 0.46 D in hyperopes (P = .02) and from 0.64 to 0.26 D in myopes (P < .002). CDVA was maintained in both groups, with only one patient in each worse than 20/20. There was a nonsignificant trend toward less haze in the patients receiving mitomycin C (5.1% vs 25%, P = .14). Linear regression showed a tendency toward overtreatment in the myopic group. PRK is safe and highly effective for patients who previously underwent LASIK and in whom the surgeon would prefer not to perform a flap-lift enhancement. Copyright 2014, SLACK Incorporated.
Aslanides, Ioannis M; Mukherjee, Achyut N
Purpose To report the long term outcomes, safety, stability, and efficacy in a pilot series of simultaneous hyperopic laser assisted in situ keratomileusis (LASIK) and corneal crosslinking (CXL). Method A small cohort series of five eyes, with clinically suboptimal topography and/or thickness, underwent LASIK surgery with immediate riboflavin application under the flap, followed by UV light irradiation. Postoperative assessment was performed at 1, 3, 6, and 12 months, with late follow up at 4 years, and results were compared with a matched cohort that received LASIK only. Results The average age of the LASIK-CXL group was 39 years (26–46), and the average spherical equivalent hyperopic refractive error was +3.45 diopters (standard deviation 0.76; range 2.5 to 4.5). All eyes maintained refractive stability over the 4 years. There were no complications related to CXL, and topographic and clinical outcomes were as expected for standard LASIK. Conclusion This limited series suggests that simultaneous LASIK and CXL for hyperopia is safe. Outcomes of the small cohort suggest that this technique may be promising for ameliorating hyperopic regression, presumed to be biomechanical in origin, and may also address ectasia risk. PMID:23576861
Aslanides, Ioannis M; Mukherjee, Achyut N
To report the long term outcomes, safety, stability, and efficacy in a pilot series of simultaneous hyperopic laser assisted in situ keratomileusis (LASIK) and corneal crosslinking (CXL). A small cohort series of five eyes, with clinically suboptimal topography and/or thickness, underwent LASIK surgery with immediate riboflavin application under the flap, followed by UV light irradiation. Postoperative assessment was performed at 1, 3, 6, and 12 months, with late follow up at 4 years, and results were compared with a matched cohort that received LASIK only. The average age of the LASIK-CXL group was 39 years (26-46), and the average spherical equivalent hyperopic refractive error was +3.45 diopters (standard deviation 0.76; range 2.5 to 4.5). All eyes maintained refractive stability over the 4 years. There were no complications related to CXL, and topographic and clinical outcomes were as expected for standard LASIK. This limited series suggests that simultaneous LASIK and CXL for hyperopia is safe. Outcomes of the small cohort suggest that this technique may be promising for ameliorating hyperopic regression, presumed to be biomechanical in origin, and may also address ectasia risk.
Blais, B R
Employers' attitudes toward the use of contact lenses at work have become less discriminatory as lenses have improved and numerous studies have demonstrated their safety, provided that additional personal protective equipment is used when necessary. In 1994, the Occupational Safety and Health Administration published its relevant Standard (29 CFR 1910), stating that "contact lenses do not pose additional hazards to the wearer...". Accommodations required by wearers of contact lenses must comply with Title I of the Americans with Disabilities Act. However, many companies still oppose their use. The recently published policy of the American College of Occupational and Environmental Medicine and the American Academy of Ophthalmology on the use of contact lenses should lead to their wider acceptance. Elements of a corporate contact lens policy are outlined. International aspects are summarized as well.
Ciolino, Joseph B.; Hudson, Sarah P.; Mobbs, Ashley N.; Hoare, Todd R.; Iwata, Naomi G.; Fink, Gerald R.
Purpose. To design a contact lens to treat and prevent fungal ocular infections. Methods. Curved contact lenses were created by encapsulating econazole-impregnated poly(lactic-co-glycolic) acid (PLGA) films in poly(hydroxyethyl methacrylate) (pHEMA) by ultraviolet photopolymerization. Release studies were conducted in phosphate-buffered saline at 37°C with continuous shaking. The contact lenses and their release media were tested in an antifungal assay against Candida albicans. Cross sections of the pre- and postrelease contact lenses were characterized by scanning electron microscopy and by Raman spectroscopy. Results. Econazole-eluting contact lenses provided extended antifungal activity against Candida albicans fungi. Fungicidal activity varied in duration and effectiveness depending on the mass of the econazole-PLGA film encapsulated in the contact lens. Conclusions. An econazole-eluting contact lens could be used as a treatment for fungal ocular infections. PMID:21527380
Narváez, Julio; Brucks, Matthew; Zimmerman, Grenith; Bekendam, Peter; Bacon, Gregory; Schmid, Kristin
To determine the degree of cyclorotation and centroid shift in the x and y axis that occurs intraoperatively during LASIK and photorefractive keratectomy (PRK). Intraoperative cyclorotation and centroid shift were measured in 63 eyes from 34 patients with a mean age of 34 years (range: 20 to 56 years) undergoing either LASIK or PRK. Preoperatively, an iris image of each eye was obtained with the VISX WaveScan Wavefront System (Abbott Medical Optics Inc) with iris registration. A VISX Star S4 (Abbott Medical Optics Inc) laser was later used to measure cyclotorsion and pupil centroid shift at the beginning of the refractive procedure and after flap creation or epithelial removal. The mean change in intraoperative cyclorotation was 1.48±1.11° in LASIK eyes and 2.02±2.63° in PRK eyes. Cyclorotation direction changed by >2° in 21% of eyes after flap creation in LASIK and in 32% of eyes after epithelial removal in PRK. The respective mean intraoperative shift in the x axis and y axis was 0.13±0.15 mm and 0.17±0.14 mm, respectively, in LASIK eyes, and 0.09±0.07 mm and 0.10±0.13 mm, respectively, in PRK eyes. Intraoperative centroid shifts >100 μm in either the x axis or y axis occurred in 71% of LASIK eyes and 55% of PRK eyes. Significant changes in cyclotorsion and centroid shifts were noted prior to surgery as well as intraoperatively with both LASIK and PRK. It may be advantageous to engage iris registration immediately prior to ablation to provide a reference point representative of eye position at the initiation of laser delivery. Copyright 2012, SLACK Incorporated.
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)
Khoramnia, Ramin; Auffarth, Gerd U; Rabsilber, Tanja M; Holzer, Mike P
We report a 66-year-old patient who presented with increasing hyperopia, astigmatism, and presbyopia in both eyes 8 years after bilateral laser in situ keratomileusis (LASIK) and LASIK enhancement in the left eye aiming for spectacle independence. Bilateral multifocal toric Lentis Mplus intraocular lenses (IOLs) with an embedded near segment and individually customized cylinder correction were implanted uneventfully following phacoemulsification. The Haigis-L formula after previous hyperopia correction was chosen for IOL power calculation and provided reliable results. Emmetropia was targeted and achieved. Three months postoperatively, the uncorrected distance visual acuity had increased from 0.40 logMAR to 0.10 logMAR in the right eye and from 0.20 logMAR to 0.00 logMAR in the left eye. The patient gained 6 lines of uncorrected near visual acuity: 0.20 logMAR in the right eye and 0.10 logMAR in the left eye. This case shows that customized premium IOL implantation can provide accurate results even in challenging cases. The International Vision Correction Research Centre, Department of Ophthalmology, University of Heidelberg, Heidelberg, Germany, has received research grants, lecture fees, and travel reimbursement from Oculentis GmbH. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.
YES/NO Have you had corrective eye surgery ( PRK / LASIK )? YES/NO Have you been diagnosed or treated for any eye injuries or disease(s)? YES...without the use of any type of corrective lenses (glasses or contacts). Those with corrective vision through LASIK or PRK are qualified. Additionally...breast implants? YES/NO Do you wear corrective lenses (glasses/contact lenses)? YES/NO Have you had corrective eye surgery ( PRK / LASIK
Yokogawa, Hideaki; Kobayashi, Akira; Tagawa, Kosaku; Sugiyama, Kazuhisa
To demonstrate alterations of corneal K-structures (sub-Bowman's fibrous structures) after keratorefractive surgery by in vivo laser confocal microscopy and to look for association of K-structures with fluorescein-stained anterior corneal mosaic (ACM). Five patients (nine eyes) participated in this study. For four patients, one eye was evaluated after laser in situ keratomileusis (LASIK) and the other after epipolis-laser in situ keratomileusis (epi-LASIK). For one patient, the left eye was evaluated after epithelial debridement. A photograph of the ACM was obtained. Central corneal regions were scanned by Heidelberg Retina Tomograph 2 Rostock Cornea Module (Heidelberg Engineering GmbH, Heidelberg, Germany). The ACM and K-structures disappeared in all corneas after epi-LASIK, but not after LASIK and epithelial debridement cornea. The presence of K-structures and ACM may be an index to identify eyes that had a previous refractive surgical procedure (surface ablation or LASIK) and be a health index of Bowman layer and adjacent anterior stroma. Copyright 2010, SLACK Incorporated.
Xu, Ye-Sheng; Xie, Wen-Jia; Yao, Yu-Feng
To report surgical management and favorable outcome in a case with delayed repair of traumatic laser in situ keratomileusis (LASIK) flap dislocation with shrinkage and folds. A 30-year-old man with a five-year history of bilateral LASIK experienced blunt trauma to his right eye followed by decreased vision for 5 weeks. The surgical management included initially softening the flap by irrigation with balanced salt solution (BSS). The shrinkage folds were carefully and gently stretched by scraping with a 26-gauge cannula accompanied by BSS irrigation. All of the epithelial ingrowth on the flap inner surface and on the bed was thoroughly debrided by scraping and irrigation. After the flap was repositioned to match its original margin, a soft bandage contact lens was placed. At his initial visit, slit-lamp microscopy and optical coherence tomography (OCT) showed shrinkage of the LASIK flap with an elevated margin approximately 3 mm above the original position. The flap covered half of the pupil and had multiple horizontal folds. Two months after surgery, the flap remained well positioned with only faint streaks in the anterior stroma. The uncorrected visual acuity of the right eye was 20/20 with a manifest refraction of Plano. For delayed repair of traumatically dislocated LASIK flaps, sufficient softening by BSS, stretching the shrinkage folds, and thorough debridement of ingrowth epithelium enable resetting the flap and provide satisfactory results.
Xu, Ye-sheng; Xie, Wen-jia; Yao, Yu-feng
Objective: To report surgical management and favorable outcome in a case with delayed repair of traumatic laser in situ keratomileusis (LASIK) flap dislocation with shrinkage and folds. Methods: A 30-year-old man with a five-year history of bilateral LASIK experienced blunt trauma to his right eye followed by decreased vision for 5 weeks. The surgical management included initially softening the flap by irrigation with balanced salt solution (BSS). The shrinkage folds were carefully and gently stretched by scraping with a 26-gauge cannula accompanied by BSS irrigation. All of the epithelial ingrowth on the flap inner surface and on the bed was thoroughly debrided by scraping and irrigation. After the flap was repositioned to match its original margin, a soft bandage contact lens was placed. Results: At his initial visit, slit-lamp microscopy and optical coherence tomography (OCT) showed shrinkage of the LASIK flap with an elevated margin approximately 3 mm above the original position. The flap covered half of the pupil and had multiple horizontal folds. Two months after surgery, the flap remained well positioned with only faint streaks in the anterior stroma. The uncorrected visual acuity of the right eye was 20/20 with a manifest refraction of Plano. Conclusions: For delayed repair of traumatically dislocated LASIK flaps, sufficient softening by BSS, stretching the shrinkage folds, and thorough debridement of ingrowth epithelium enable resetting the flap and provide satisfactory results. PMID:28585430
Li, Yan; Shekhar, Raj; Huang, David
Optical coherence tomography (OCT) provides a non-contact and non-invasive means to visualize the corneal anatomy at micron scale resolution. We obtained corneal images from an arc-scanning (converging) OCT system operating at a wavelength of 830nm and a fan-shaped-scanning high-speed OCT system with an operating wavelength of 1310nm. Different scan protocols (arc/fan) and data acquisition rates, as well as wavelength dependent bio-tissue backscatter contrast and optical absorption, make the images acquired using the two systems different. We developed image-processing algorithms to automatically detect the air-tear interface, epithelium-Bowman's layer interface, laser in-situ keratomileusis (LASIK) flap interface, and the cornea-aqueous interface in both kinds of images. The overall segmentation scheme for 830nm and 1310nm OCT images was similar, although different strategies were adopted for specific processing approaches. Ultrasound pachymetry measurements of the corneal thickness and Placido-ring based corneal topography measurements of the corneal curvature were made on the same day as the OCT examination. Anterior/posterior corneal surface curvature measurement with OCT was also investigated. Results showed that automated segmentation of OCT images could evaluate anatomic outcome of LASIK surgery.
Teus, M A; Arruabarrena, C; Hernández-Verdejo, J L; Cañones, R; Mikropoulos, D G
Purpose To analyze the effect of ocular residual astigmatism (ORA) on the effectiveness of LASIK for treating high myopic astigmatism. Methods This is an observational, cross-sectional study. We studied 116 consecutive myopic eyes with −3 diopters (D) or more of astigmatism that underwent LASIK surgery. The magnitude of uncorrected residual refractive astigmatism 3 months postoperatively was measured. Results The mean preoperative cylinder was −4.0±0.83 D (range, −7.5 to −3 D) and the mean preoperative ORA was 0.82±0.5 D. The mean residual refractive cylinder 3 months postoperatively was −0.78±0.83 D (range, −3 to 0 D). No correlation was found between ORA and the refractive cylinder 3 months postoperatively (P=0.6). Conclusion In eyes with high myopic astigmatism undergoing LASIK, ORA was not correlated with the residual postoperative cylinder. PMID:24971989
Kymionis, George D; Portaliou, Dimitra M; Karavitaki, Alexandra E; Krasia, Maria S; Kontadakis, Georgios A; Stratos, Aimilianos; Yoo, Sonia H
To describe the visual outcomes of three patients who had LASIK flap buttonhole and were treated immediately with photorefractive keratectomy (PRK) and topical mitomycin C (MMC) 0.02%. Three patients underwent bilateral LASIK with the SCHWIND Carriazo-Pendula 90 microm head microkeratome. In all three cases, a buttonhole flap occurred in the left eye. The flap was repositioned and phototherapeutic keratectomy for 50 microm was used for epithelial removal while immediate PRK with MMC was performed to treat the buttonhole flap. Three months after the procedure, uncorrected distance visual acuity and corrected distance visual acuity were 20/20 with regular topographic findings. Using PRK with MCC immediately after the occurrence of the LASIK flap buttonhole may be an effective treatment.
Dhaliwal, Deepinder K; Mather, Rookaya
Lamellar refractive surgery has evolved into LASIK, which is a widely performed, versatile procedure with a high patient acceptance. In this chapter, the two main components of LASIK were discussed: flap creation and stromal ablation. In each of these areas, the authors explored current technology and new advances, including the femtosecond laser and wavefront-guided ablations. Expanded indications and therapeutic application of LASIK also have come to the forefront. The treatment of anisomyopic amblyopia in the pediatric population is a prime example and was discussed fully in this chapter. The field of refractive surgery has never been stagnant. Surgeons and scientists continue to explore new modalities to increase safety, to improve results, and to broaden applications that benefit the patient population.
Camps, Vicente J; Miret, Juan J; García, Celia; Tolosa, Angel; Piñero, David P
To simulate the optical performance of three presbyopia-correcting intraocular lenses (IOLs) implanted in eyes with previous laser refractive surgery. A simulation of the through-focus modulation transfer function (MTF) was performed for three presbyopia-correcting IOLs (Mplus, Oculentis GmbH, Berlin, Germany; Symfony, Johnson & Johnson Vision, Santa Ana, CA; and Mini Well, SIFI S.p.A., Lavinaio, Italy) in one eye with previous myopic LASIK and another with hyperopic LASIK. Real topographic data and the wavefront aberration profile of each IOL obtained with a Hartmann-Shack sensor were used. In the eye with myopic LASIK, all IOLs lost optical quality at near and intermediate distances for 4- and 4.7-mm pupil size. For 3-mm pupil size, the Mini Well IOL showed the best intermediate and near MTF and maintained the far focus independently of the pupil. In the eye with hyperopic LASIK, the Mini Well IOL showed an intermediate, distance, and -4.00-diopter (D) foci for all pupils. The Symfony IOL showed a depth of focus at far and intermediate distance for 3-mm and a focus at -2.50 D in the rest. The Mplus showed a focus of -4.50 and -3.00 D for the 3- and 4-mm pupil, respectively. The Mini Well and Symfony IOLs seem to work better than the Mplus IOL in eyes with previous myopic LASIK. With previous hyperopic LASIK, the Mini Well IOL seems to be able to provide acceptable near, intermediate, and far foci for all pupil sizes. These findings should be confirmed in future clinical studies. [J Refract Surg. 2018;34(4):222-227.]. Copyright 2018, SLACK Incorporated.
Purpose. To compare the change of anterior corneal higher-order aberrations (HOAs) after laser in situ keratomileusis (LASIK), wavefront-guided LASIK with iris registration (WF-LASIK), femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK), and small incision lenticule extraction (SMILE). Methods. In a prospective study, 82 eyes underwent LASIK, 119 eyes underwent WF-LASIK, 88 eyes underwent FS-LASIK, and 170 eyes underwent SMILE surgery. HOAs were measured with Pentacam device preoperatively and 6 months after surgery. The aberrations were described as Zernike polynomials, and analysis focused on total HOAs, spherical aberration (SA), horizontal coma, and vertical coma over 6 mm diameter central corneal zone. Results. Six months postoperatively, all procedures result in increase of anterior corneal total HOAs and SA. There were no significant differences in the induced HOAs between LASIK and FS-LASIK, while SMILE induced fewer total HOAs and SA compared with LASIK and FS-LASIK. Similarly, WF-LASIK also induced less total HOAs than LASIK and FS-LASIK, but only fewer SA than FS-LASIK (P < 0.05). No significant difference could be detected in the induced total HOAs and SA between SMILE and WF-LASIK, whereas SMILE induced more horizontal coma and vertical coma compared with WF-LASIK (P < 0.05). Conclusion. FS-LASIK and LASIK induced comparable anterior corneal HOAs. Compared to LASIK and FS-LASIK, both SMILE and WF-LASIK showed advantages in inducing less total HOAs. In addition, SMILE also possesses better ability to reduce the induction of SA in comparison with LASIK and FS-LASIK. However, SMILE induced more horizontal coma and vertical coma compared with WF-LASIK, indicating that the centration of SMILE procedure is probably less precise than WF-LASIK. PMID:27818792
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.
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. PMID:27748361
... lenses to FDA’s MedWatch reporting program . How to Report Problems Here’s how you can help: If you ... selling contact lenses over the Web, you should report it to the FDA . If you don’t ...
Carrasquillo, Karen G; Rand, Janet; Talamo, Jonathan H
To evaluate the efficacy of intracorneal ring segments to treat keratoconus and post-laser in situ keratomileusis (LASIK) keratectasia implanted by using either mechanical dissection or a femtosecond laser. Thirty-three eyes of 29 patients had intracorneal ring segments implanted by using mechanical dissection (17 eyes) or a femtosecond laser (16 eyes). Mean follow-up was 10.3 months. Parameters assessed before and after surgery included uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refractive spherical equivalent (MRSE), refractive cylinder (RC), best contact lens-corrected visual acuity (BCLVA), and contact lens tolerance. Statistically significant changes occurred for all parameters when we analyzed all 33 eyes as 1 group. Mean UCVA LogMar values improved from 1.0 +/- 0.3 (20/200) to 0.6 +/- 0.4 (20/80) (P < 0.0005). Mean BSCVA changed from 0.3 +/- 0.2 (20/40) to 0.2 +/- 0.2 (20/30) (10%; P < 0.05), and MRSE from -9 +/- 4 to -7 +/- 4 D (P < 0.05; 20%). There was a decrease of 0.5 D or more of RC in 62% of eyes. BCLVA improved from 0.2 +/- 0.2 (20/30) to 0.1 +/- 0.1 (20/25) after surgery (P < 0.02). Contact lens tolerance improved in 81% of eyes. There was no statistically significant difference in outcomes between mechanical dissection and femtosecond laser-assisted techniques. However, although statistical power was adequate to detect changes in clinical parameters as a result of surgery, it was not sufficient to conclusively show such differences between surgical techniques. For mild to moderate cases of keratoconus and post-LASIK keratectasia, the use of a femtosecond laser for Intacs channel creation seems as effective as mechanical dissection. Future studies are warranted to further evaluate channel creation by a femtosecond laser.
Parkhurst, Gregory D
Purpose 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). Patients and methods 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. Results 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). Conclusion 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. PMID:27418804
Grossman, Scott A.; Narayan, Ramesh
The proposal made by Paczynski (1987) that the arcs of blue light found recently in two cluster cores are gravitationally lensed elongated images of background galaxies is investigated. It is shown that lenses that are circularly symmetric in projection produce pairs of arcs, in conflict with the observations. However, more realistic asymmetric lenses produce single arcs, which can become as elongated as the observed ones whenever the background galaxy is located on or close to a cusp caustic. Detailed computer simulations of lensing by clusters using a reasonable model of the mass distribution are presented. Elongated and curved lensed images longer than 10 arcsec occur in 12 percent of the simulated clusters. It is concluded that the lensing hypothesis must be taken seriously.
Efron, Nathan; Morgan, Philip B
Contact lenses are mainly fitted by registered optometrists and contact lens opticians in the UK. Data we have gathered from annual contact lens fitting surveys over the past 12 years indicate that, on average, registered optometrists and contact lens opticians undertake 3.2 and 7.1 contact lens fits per week (p<0.0001). More experienced practitioners tend to fit older patients. Practitioners fitting more lenses per year tend to fit a higher proportion of soft lenses. Contact lens opticians tend to fit a higher proportion of patients with planned replacement and daily disposable lenses compared with optometrists.
Wichmann, Matthias; Scherger, Benedikt; Schumann, Steffen; Lippert, Sina; Scheller, Maik; Busch, Stefan F; Jansen, Christian; Koch, Martin
Typical lenses suffer from Fresnel reflections at their surfaces, reducing the transmitted power and leading to interference phenomena. While antireflection coatings can efficiently suppress these reflections for a small frequency window, broadband antireflection coatings remain challenging. In this paper, we report on the simulation and experimental investigation of Brewster lenses in the THz-range. These lenses can be operated under the Brewster angle, ensuring reflection-free transmission of p-polarized light in an extremely broad spectral range. Experimental proof of the excellent focusing capabilities of the Brewster lenses is given by frequency and spatially resolved focus plane measurements using a fiber-coupled THz-TDS system.
Sharma, Munish; Wachler, Brian S Boxer; Chan, Colin C K
To understand what level of higher order aberrations increases the relative risk of visual symptoms in patients after myopic LASIK. This study was a retrospective comparative analysis of 103 eyes of 62 patients divided in two groups, matched for age, gender, pupil size, and spherical equivalent refraction. The symptomatic group comprised 36 eyes of 24 patients after conventional LASIK with different laser systems evaluated in our referral clinic and the asymptomatic control group consisted of 67 eyes of 38 patients following LADARVision CustomCornea wavefront LASIK. Comparative analysis was performed for uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), contrast sensitivity, refractive cylinder, and higher order aberrations. Wavefront analysis was performed with the LADARWave aberrometer at 6.5-mm analysis for all eyes. Blurring of vision was the most common symptom (41.6%) followed by double image (19.4%), halo (16.7%), and fluctuation in vision (13.9%) in symptomatic patients. A statistically significant difference was noted in UCVA (P = .001), BSCVA (P = .001), contrast sensitivity (P < .001), and manifest cylinder (P = .001) in the two groups. The percentage difference between the symptomatic and control group mean root-mean-square (RMS) values ranged from 157% to 206% or 1.57 to 2.06 times greater. Patients with visual symptoms after LASIK have significantly lower visual acuity and contrast sensitivity and higher mean RMS values for higher order aberrations than patients without symptoms. Root-mean-square values of greater than two times the normal after-LASIK population for any given laser platform may increase the relative risk of symptoms.
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
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…
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.
Suchecki, Jeanine K; Donshik, Peter; Ehlers, William H
Complications associated with contact lenses range from mild to severe and occur with all lens modalities. Contact lens wear can cause a change in corneal physiology, which can lead to epithelial, stromal, and endothelial compromise. Other complications include lens deposition, allergic conjunctivitis, giant papillary conjunctivitis, peripheral infiltrates, microbial keratitis, and neovascularization. Pre-existing conditions can contribute to these complications, or they can occur in association with contact lens wear and care regimens. Patient-related factors, such as alteration of the recommended wearing or replacement schedules and noncompliance with recommended contact lens care regimens for economic reasons, convenience, or in error, contribute to contact lens-related complications and have led to difficulty in accurate determination of complication rates among the various lens wear modalities. Complications may require discontinuation of contact lenses, topical therapy, and changes in contact lens wearing schedules, materials, and care solutions. On initial lens fitting and follow-up evaluations, practitioners should review contact lens replacement and cleaning regimens with patients and discuss complications. To avoid serious complications, patients should be reminded to remove their contact lenses as soon as ocular irritation occurs, and to call their eye care practitioner immediately if symptoms persist.
Dürsteler, Juan Carlos
A review of the use of aspherics in the last decades, understood in a broad sense as encompassing single-vision lenses with conicoid surfaces and free-form and progressive addition lenses (PALs) as well, is provided. The appearance of conicoid surfaces to correct aphakia and later to provide thinner and more aesthetically appealing plus lenses and the introduction of PALs and free-form surfaces have shaped the advances in spectacle lenses in the last three decades. This document basically considers the main target optical aberrations, the idiosyncrasy of single lenses for correction of refractive errors and the restrictions and particularities of PAL design and their links to science vision and perception.
Vijay, Ajay Kumar; Zhu, Hua; Ozkan, Jerome; Wu, Duojia; Masoudi, Simin; Bandara, Rani; Borazjani, Roya N; Willcox, Mark D P
The objective of this study was to determine the bacterial adhesion to various silicone hydrogel lens materials and to determine whether lens wear modulated adhesion. Bacterial adhesion (total and viable cells) of Staphylococcus aureus (31, 38, and ATCC 6538) and Pseudomonas aeruginosa (6294, 6206, and GSU-3) to 10 commercially available different unworn and worn silicone hydrogel lenses was measured. Results of adhesion were correlated to polymer and surface properties of contact lenses. S. aureus adhesion to unworn lenses ranged from 2.8 × 10 to 4.4 × 10 colony forming units per lens. The highest adhesion was to lotrafilcon A lenses, and the lowest adhesion was to asmofilcon A lenses. P. aeruginosa adhesion to unworn lenses ranged from 8.9 × 10 to 3.2 × 10 colony forming units per lens. The highest adhesion was to comfilcon A lenses, and the lowest adhesion was to asmofilcon A and balafilcon A lenses. Lens wear altered bacterial adhesion, but the effect was specific to lens and strain type. Adhesion of bacteria, regardless of genera/species or lens wear, was generally correlated with the hydrophobicity of the lens; the less hydrophobic the lens surface, the greater the adhesion. P. aeruginosa adhered in higher numbers to lenses in comparison with S. aureus strains, regardless of the lens type or lens wear. The effect of lens wear was specific to strain and lens. Hydrophobicity of the silicone hydrogel lens surface influenced the adhesion of bacterial cells.
Foo, Say Kiang; Kaur, Sharanjeet; Abd Manan, Faudziah; Low, Aloysius Joseph
Background: IntraLASIK is a LASIK surgery that involved IntraLase femtosecond laser for the corneal flap creating. The objective of this research was to investigate and compare the changes in tear status at 1 and 3 months after undergoing conventional IntraLASIK with Bausch & Lomb PlanoScan (PS) algorithm, Bausch & Lomb Zyoptix Tissue Saving (ZTS) algorithm, and wavefront-guided (WG) IntraLASIK with VISX CustomVue. Methods: Tear status of 36 patients who were divided into 3 groups depending on the type of IntraLASIK they underwent (PS, n = 13; ZTS, n = 9; WG, n = 14) was evaluated. Tear status was determined by classifying the category of the thickness of pre-corneal tear lipid layer, non-invasive tear break-up time, and tear meniscus height. Repeated measures analysis of variance (ANOVA) and one way ANOVA were used for the statistical analyses. Results: The category of the thickness of tear lipid layer, non-invasive tear break up time and tear meniscus height were neither significantly changed after IntraLASIK for all groups nor showed significant difference among groups at 1 and 3 months post-IntraLASIK (P > 0.05). Blinking rate and palpebral aperture also had no significant changed after IntraLASIK. Conclusion: Both conventional (PS and ZTS) and WG IntraLASIK did not affect tear status up to 3 months post-IntraLASIK. WG IntraLASIK did not show superiority in preserving tear status 1 and 3 months post-surgery compared with conventional IntraLASIK. PMID:22135584