Daily Disposable Lenses Research Articles

Dendritic immune cell densities in the central cornea associated with soft contact lens types and lens care solution types: a pilot study

BackgroundThe purpose of this study was to assess whether differences in central corneal dendritic immune cell densities associated with combinations of soft contact lenses and lens care solutions could be detected by in vivo confocal microscopy.MethodsParticipants were adults naïve to contact lens wear (n = 10) or who wore soft contact lenses habitually on a daily-wear schedule (n = 38) or on a study-assigned schedule for 30 days with daily disposable silicone hydrogel lenses (n = 15). Central corneas were scanned using an in vivo confocal microscope. Cell densities were compared among groups by demographic parameters, lens materials, and lens care solutions (polyhexamethylene biguanide [PHMB], polyquaternium-1 and myristamidopropyl dimethylamine [PQ/MAPD], peroxide, or blister pack solution [for daily disposable lenses]).ResultsAmong lens wearers, no associations were observed between immune cell densities and age, gender, or years of lens-wearing experience. Mean cell density was significantly lower (P < 0.01) in nonwearers (29 ± 23 cells/mm2, n = 10) than in lens wearers (64 ± 71 cells/mm2, n = 53). Mean cell density was lower (P = 0.21) with traditional polymer lenses (47 ± 44 cells/mm2, n = 12) than with silicone hydrogel lenses (69 ± 77 cells/mm2, n = 41). Lowest to highest mean density of immune cells among lens wearers was as follows: PQ/MAPD solution (49 ± 28 cells/mm2), blister pack solution (63 ± 81 cells/mm2), PHMB solution (66 ± 44 cells/mm2), and peroxide solution (85 ± 112 cells/mm2).ConclusionIn this pilot study, in vivo confocal microscopy was useful for detecting an elevated immune response associated with soft contact lenses, and for identifying lens-related and solution-related immune responses that merit further research.

An international analysis of contact lens compliance

To evaluate compliance to contact lens use in 14 countries, and to identify wearer attributes which indicate lower compliance levels. A web-based survey was undertaken by 4021 contact lens wearers, revealing information about demographics, and lens and solution information including daily handling details, case care and aftercare frequency. Particular attention was paid to eight modifiable compliance-related behaviours which are associated with an increased risk of microbial keratitis. Full compliance was very rare for most lens users, although better (15% of wearers) for daily disposable lenses. Reduced compliance was demonstrated in South Korea, and for young male full-time contact lens users, especially those who have not consulted their eyecare practitioner for some time. The behaviours associated with the lowest levels of compliance were rubbing and rinsing, handwashing, correct lens replacement and case cleaning. Given other recent literature, which suggests improved contact lens compliance with regular self-review exercises, we encourage clinical colleagues to particularly examine case cleaning, handwashing and rubbing and rinsing at aftercare examinations, especially in young male wearers.

Survey of Contact Lens Prescribing to Infants, Children, and Teenagers

To determine the types of contact lenses prescribed for infants (aged 0 to 5 years), children (6 to 12 years), and teenagers (13 to 17 years) around the world. Up to 1000 survey forms were sent to contact lens fitters in each of 38 countries between January and March every year for 5 consecutive years (2005 to 2009). Practitioners were asked to record data relating to the first 10 contact lens fits or refits performed after receiving the survey form. Data were received relating to 105,734 fits [137 infants, 1,672 children, 12,117 teenagers, and 91,808 adults (age ≥ 18 years)]. The proportion of minors (<18 year old) fitted varied considerably between nations, ranging from 25% in Iceland to 1% in China. Compared with other age groups, infants tend to be prescribed a higher proportion of rigid, soft toric, and extended wear lenses, predominantly as refits for full-time wear, and fewer daily disposable lenses. Children are fitted with the highest proportion of daily disposable lenses and have the highest rate of fits for part-time wear. Teenagers have a similar lens fitting profile to adults, with the main distinguishing characteristic being a higher proportion of new fits. Orthokeratology fits represented 28% of all contact lenses prescribed to minors. Patterns of contact lens prescribing to infants and children are distinctly different to those of teenagers and adults in a number of respects. Clinicians can use the data presented here to compare their own patterns of contact lens prescribing to minors.

Risk Factors for Contact Lens Complications in US Clinical Practices

To determine significant risk factors for any inflammatory and infectious events with soft contact lenses (SCL) in a large retrospective clinical chart review. Charts of patients who presented for SCL care from October 2005 through March 2006 were reviewed and observed for a potential of at least 2 years. Charts from those with office visits involving an event-requiring pharmacologic treatment and/or interruption of SCL wear were scanned and later adjudicated by a masked panel. Significant factors from a univariate analysis were included in a multivariate analysis for all events and subcategories of events separately. Overnight wear was not consistently recorded and was not analyzed. Charts from 1276 SCL wearers comprised 4120 visits and 1454 years of SCL wear (2908 eye/yr) and included 306 events of interest in 228 patients. In a multivariate analysis, age <25 years was significantly associated with presenting any event, inflammatory events, and infectious events that may or may not be CL-related [incidence rate ratio (IRR) = 1.3; 95% CI, 1.0 to 1.7; 2.6X, 1.5 to 4.6; and 2.0X, 1.2 to 3.3, respectively]. Ametropia >5.00 D increased risk of any event (IRR = 1.5; 1.2 to 1.9) and for other infectious events (IRR = 1.9; 1.2 to 3.2). Use of daily disposable lenses associated with lid irritation (IRR = 4.5; 2.1 to 9.8) but was not significantly associated with any other type of events. New and hydrogel lens wearers had a lower incidence of all event types (IRR = 0.07; 0.01 to 0.46 and 0.77; 0.59 to 0.99, respectively). Eighty-two percent of these SCL wearers did not present with any complications during the observation period >2 years. The risk factors for inflammatory and infectious events among SCL wearers in clinical practice are similar to those reported in prospective clinical trials. High ametropia and age <25 years are the risk factors that impact the most types of events.

Daily disposable contact lens prescribing around the world

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

Practitioners’ analysis of contact lens practice in Hong Kong

The aims of this survey were to appraise contact lens practice and care systems used in Hong Kong between March 2007 and February 2008, and to evaluate the attitude of practitioners towards prescribing different types of contact lenses. Questionnaires were sent out to 797 optometrists licensed to fit contact lenses in Hong Kong in March 2008. The response rate was 27%. About 20% of contact lens patients (as reported by the respondents) were new wearers. Over 90% of contact lens patients were wearing soft contact lenses. Among soft contact lenses, the use of daily disposable and silicone hydrogel lenses had increased from 27% and 3% in 2002 to 37% and 21% in 2008, respectively. Less than 10% were rigid contact lens wearers. For astigmats fitted with soft lenses, only about 46% were fitted with toric lenses. For presbyopes using contact lenses, the majority (57%) were fitted with single vision lenses with over-spectacles, followed by monovision (29%). The most commonly recommended soft lens disinfecting system was multipurpose solution (74%). Less than 20% of the respondents reported confidence in prescribing orthokeratology lenses. Soft contact lenses continued to dominate the contact lens market in Hong Kong, with silicone hydrogel and daily disposable lenses becoming increasingly popular. The use of toric and bifocal lenses was still not popular among practitioners. Multipurpose solutions were still the care systems of choice by practitioners in Hong Kong.

Objective clinical performance of ‘comfort-enhanced’ daily disposable soft contact lenses

To examine the objective clinical performance of 'comfort-enhanced' daily disposable contact lenses over a 16-h day. Four contact lenses (Hilafilcon B, Etafilcon A Plus, Nelfilcon A and Nelfilcon A Plus) were evaluated in an investigator masked, open label trial at the end of a week's bilateral wear. Pre-lens non-invasive tear break-up time (PL-NITBUT), tear prism height, bulbar hyperaemia and ocular surface temperature (OST) were measured with the lens in situ at 8, 12 and 16h of wear. There was no difference between how many hours the lenses types were worn each day (F=0.90, p=0.44). The PL-NITBUT decreased with the duration of daily lens wear (F=32.0, p<0.001) and was more stable with Nelfilcon A Plus (F=6.00, p=0.002) than with the other lenses evaluated. Bulbar blood vessels increased in coverage (F=11.5, p<0.001) but not overall redness (F=0.0, p=0.99) with the duration of daily lens wear, but there was no difference between the lenses (p>0.05). The tear prism height decreased with the duration of daily wear (F=27.0, p<0.001) and differed between lenses (F=2.9, p=0.04). The OST decreased with the duration of lens wear (F=119.7, p<0.001) and was reduced by daily disposable lens wear (F=7.88, p<0.001), but did not differ between lenses (F=0.88, p=0.45). Objective measures of tear film indicated a difference between the lenses evaluated for PL-NITBUT and tear prism height, but not for wearing time or bulbar conjunctival hyperaemia. Therefore clinical benefits of daily disposable 'comfort enhancing' contact lenses can be measured, but challenges remain in producing contact lenses that do not compromise anterior eye physiology over the whole day.

Patient and practitioner compliance with silicone hydrogel and daily disposable lens replacement in Canada

Purpose: To assess current recommendations by optometrists for replacement frequency (RF) of silicone hydrogels (SH) and daily disposable (DD) contact lenses in Canada, determine rates of non-compliance with recommendations by both the optometrist and patient, and investigate reasons for non-compliance.&#x0D; Methods: Survey packages were sent to optometrists in Canada who had agreed to participate. Patients completed survey questions regarding demographics and contact lens wearing patterns, including recommended and actual contact lens RF. Optometrists were asked to provide lens information and their recommendation for RF. Fifty-eight optometrists returned 654 surveys, of which 578 were eligible for analysis.&#x0D; Results: Seventy percent of patients were female with a median age of 32 years. Lens type distribution was 18% DD, 35% two-week SH, and 47% one-month SH. Six percent were worn for extended wear. Daily wear median wearing time was 12 hours/day, a median of five days/week for DD, seven days/week for SH (two-week and one-month). Optometrists’ recommendations were non-compliant with the manufacturers’ recommended RF for 6% of DD, 35% of two week, and 2% of one-month patients. Patients were non-compliant with recommendations from both the manufacturer and optometrist for 12% of DD, 43% of two-week, and 31% of one-month lens wearers. The most common reason for non-compliance was forgetting which day to replace lenses. Fifty-six percent thought a reminder system would help with compliance. A higher proportion of compliant patients followed the RF because of confidence in their optometrist.&#x0D; Conclusions: Optometrists generally recommended RFs consistent with manufacturers’ recommendations for DD and one-month SH lenses but often recommended longer intervals for two-week SH lenses. Patients were most compliant when wearing DD lenses and least compliant when wearing two-week SH lenses. Communication between the patient and optometrists concerning the risks of non-compliance, or initiating a reminder system might improve compliance.

In Vitro Contact Angle Analysis and Physical Properties of Blister Pack Solutions of Daily Disposable Contact Lenses

The purpose of this study was to measure the advancing and receding contact angles (CAs) of five daily disposable (DD) lenses and the osmolality, surface tension (ST), and pH of each blister pack solution. The advancing and receding CAs were measured directly out of the blister pack for five DD lenses: omafilcon A (CooperVision), nelfilcon A (CIBA Vision), modified nelfilcon A (CIBA Vision), etafilcon A (Johnson & Johnson), and narafilcon A (Johnson & Johnson). Advancing CAs were measured using sessile drop and Wilhelmy balance methods. Receding CAs were measured using the Wilhelmy balance method. ST, pH, and osmolality were measured for each blister pack solution from all the DD lenses. The advancing CAs for the nelfilcon A lenses were statistically lower (P<0.05) than the advancing CAs of the other three lenses. The receding CAs for etafilcon A were statistically lower (P<0.05) than the receding CAs for the other four lenses. The pH of all the blister pack solutions was relatively neutral (7.01-7.43). The ST of the blister pack solution for the modified nelfilcon A was significantly lower (P<0.05) than the ST of all other blister pack solutions. The osmolality of the blister pack solutions for the etafilcon A and narafilcon A lenses were significantly higher (P<0.05) than the other blister pack solutions. The modified nelfilcon A lens had low advancing CAs and low receding CAs showing minimal hysteresis. The blister pack solution for the modified nelfilcon A lens had the lowest ST, a low osmolality, and a neutral pH.

Contact Lenses in Pediatrics Study in Singapore

Previous studies in the United States have evaluated the benefits of soft contact lenses (CLs) in 8- to 12-year-old children and 13- to 17-year-old teens. This study was undertaken in Singapore and evaluated the safety, efficacy, and physiologic performance of daily disposable soft lenses in a population of children. In this open-label, bilateral, 3-month dispensing study, 59 children (8-11 years) were fit with etafilcon A spherical or toric daily disposable lenses (1-DAY ACUVUE or 1-DAY ACUVUE for ASTIGMATISM, Vistakon, Jacksonville, FL). All subjects were neophytes requiring visual correction in both eyes. The refractive inclusion criteria were plano to -9.00 diopter (D) with astigmatism of < or =2.00DC in both eyes, or hyperopia of +0.50 to +6.00D with astigmatism of 0.75D or less. The subjects underwent follow-up evaluations, which included a questionnaire for parents and subjects, at 1 week, 1 month, and 3 months. Of the 59 subjects enrolled, 53 (90%) completed the study successfully. Six subjects were discontinued because of lens handling difficulties (four), unacceptable lens fit (one), and an adverse event (one). Adverse events were reported in three subjects, including the discontinuation, and in each case were due to a chalazion. Overall vision quality, overall comfort, and end-of-day comfort were graded significantly better at each of the follow-up visits compared with baseline with spectacles (P< or =0.0001). Both handling and reported symptoms improved during the course of the study. The questionnaire results indicated that most of both parents and subjects preferred CLs to spectacles across a wide variety of aspects including vision, comfort, handling, and appearance. Significantly, more limbal and bulbar hyperemia was noted at follow-up visits than at baseline (P=0.0001); however, no instances of hyperemia greater than grade 2 were noted at any visit. Significantly, more corneal staining was also noted at the 1- and 3-month follow-up visits than at baseline (21% at 3 months). A high proportion of Singaporean children requiring vision correction are able to successfully wear daily disposable soft CLs over a 3-month period. Overall, slit lamp findings showed the prevalence of corneal staining in this study to be 21% at 3 months, which is lower than that previously reported in adults, but higher than that reported in the US Contact Lenses in Pediatrics study (6%).

Patient and Practitioner Compliance With Silicone Hydrogel and Daily Disposable Lens Replacement in the United States

The objectives of this study were to assess current recommendations for replacement frequency (RF) of silicone hydrogel (SH) and daily disposable (DD) lenses, to determine compliance with these recommendations, and to investigate the reasons given for noncompliance. A package containing 20 patient surveys was sent to 309 eye care practitioners (ECPs) in the United States who had agreed to participate in the study. One thousand eight hundred fifty-nine completed surveys were received from 158 ECPs and 1,654 surveys were eligible for analysis. Questions related to patient demographics, lens type, lens wearing patterns, the ECP instructions for RF, and the actual patient reported RF. ECPs were asked to provide lens information and their recommendation for RF after the surveys had been completed and sealed in envelopes. All responses were anonymous. Sixty-six percent of patients were women and their mean age was 34 +/- 12 years. Eighty-eight percent of lenses were worn for daily wear, 12.8 +/- 3.2 hours a day, 6.2 +/- 1.5 days a week. Lens type distribution was 16% DD, 45% 2 week (2W) SH, and 39% 1 month (1M) SH. ECP recommendations for RF varied according to the lens type; 1% of 1M (95% CI 0.2-1.7), 4% of DD (95% CI 2.1-7.2), and 18% of 2W (95% CI 15.1-20.7) patients were given instructions that did not conform to the manufacturers' recommended RF (MRRF). When considering only those patients who were given the correct instructions for RF, 38% were not compliant with the MRRF; noncompliance rates varied according to the lens type and were 12% for DD (95% CI 8.6-17.2), 28% for 1M (95% CI 24.9-32.1), and 52% for 2W (95% CI 47.8-55.8). The most frequent reasons for over wearing lenses were "forgetting which day to replace lenses" (51%) and "to save money" (26%). Fifty-three percent believed that a reminder system would aid compliance; the most popular methods being a cell phone reminder or text message (29%) and a nominated day each week or month (26%). Discussions between the ECPs and the patients were more extensive for patients who were compliant with the MRRF. ECPs recommended RFs more frequently with DD and 1M SH lenses than with 2W SH lenses, consistent with manufacturers' recommendations. Patients were less compliant with RF than ECPs for all lens types investigated. Patients were most compliant with RF when wearing DD lenses and least compliant when wearing 2W SH lenses. Better communication facilitated greater compliance with RF. More than half of those not replacing lenses, when recommended, reported that this was because they forgot which day to replace their lenses.

How often are contact lenses worn?

There are important clinical, academic and commercial reasons for seeking to develop a comprehensive understanding of the frequency of wear of different forms of contact lenses. Data that we have gathered from annual contact lens fitting surveys over the past 12 years demonstrate that contact lenses are worn, on average, 5.4+/-1.9 days per week. Rigid lenses tended to be worn on a full-time basis, typically seven days per week. The distribution of daily disposable lens wear is bimodal, with peaks at two days and seven days per week of wear. Over the survey period there appears to have been a small trend toward the use of contact lenses on a part-time basis.

Controlled Release of High Molecular Weight Hyaluronic Acid from Molecularly Imprinted Hydrogel Contact Lenses

Current dry eye treatment includes delivering comfort agents to the eye via drops, but low bioavailability and multiple administration continues to be a barrier to effective treatment. There exists a significant unmet need for devices to treat dry eye and for more comfortable contact lenses. Using molecular imprinting strategies with an analysis of biology, we have rationally designed and synthesized hydrogel contact lenses that can release hyaluronic acid (HA) at a controlled rate. Delayed release characteristics were significantly improved through biomimetic imprinting, as multiple functional monomers provided non-covalent complexation points within nelfilcon A gels without altering structural, mechanical, or optical properties. The diffusion coefficient of 1.2 million Dalton HA was controlled by varying the number and variety of functional monomers (increasing the variety lowered the HA diffusion coefficient 1.5 times more than single functional monomers, and 1.6 times more than nelfilcon A alone). HA can be delivered from a daily disposable lens at a therapeutic rate of approximately 6 microg/h for 24 h. This is the first demonstration of imprinting a large molecular weight polymer within a hydrogel and the effect of imprinting on the reptation of the long chain macromolecule from the structure.

Bilateral Corneal Erosion Due To Retail Purchase of Unfitted Prescription Contact Lenses: A Case Report

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.

Effectiveness of moisturizing daily disposable lenses with additives

Abstract Purpose Recently, contact lens manfacturers are incorporating moisture additives in their contact lenses. Examples include povidone in 1‐DAY ACUVUE MOIST lenses, polyvinyl alcohol (PVA) in DAILIES with AquaComfort lenses and hydroxypropyl‐methylcellulose, polyethylene‐glycol and PVA in the DAILIES AquaComfort Plus lenses. These two trials were aimed to compare the effectiveness of these additives to general lens performance. Methods In the first trial, 20 investigators in the US and Germany enrolled 276 subjects currently wearing nelfilcon A with PVA (nefA+1) lenses in daily disposable modality of comparison to nelfilcon A with moisturizing additives (HPMC, PEG and PVA (nefA+3) for ten days. In the second trial, 14 investigators in Germany enrolled 314 current daily disposable wearers to wear nelfilcon A with moisturizing additives HPMC, PEG and PVA (nefA+3), and etafilcon A with added PVP (etaA+1) for one week each. Results 273 subjects completed the first trial. Comfort upon insertion was rated 9.1 for nelfilcon A with moisturizing additives (nefA+3) and 8.7 for nelfilcon A lenses (nefA+1); comfort during the day was 8.7 and 8.7, respectively; end of day comfort was 7.9 and 7.2, respectively; overall comfort was 8.6 and 8.4, respectively. 309 subjects completed the second trial. Comfort upon insertion was rated 8.6 for nefA+3 and 7.6 for etaA+1; comfort during the day was 8.4 and 7.8, respectively; end of day comfort was 7.2 and 6.6, respectively; overall comfort was 8.4 and 7.5, respectively. Conclusion Mean comfort ratings were significantly in favor of nelfilcon A with additives HPMC, PEG and PVA in both trials. Future innovations in daily disposable lenses with added moisturizes to last throughout the day should be expected. Commercial interest

Risk Factors for Microbial Keratitis with Contemporary Contact Lenses: A Case-Control Study

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 safer soft lenses. These findings suggest that lens/ocular surface interactions may be more important in the development of corneal infection than oxygen levels and CL case contamination.

An Early Assessment of Silicone Hydrogel Safety: Pearls and Pitfalls, and Current Status

The contact lens industry has evolved and now provides many choices, including continuous wear, overnight orthokeratology, frequent-replacement lenses, daily-disposable lenses, and many alternatives in systems of care and maintenance. Epidemiologic studies to date have shown that how a lens is worn, particularly if worn overnight, can increase the risk of microbial keratitis. However, the risk of silicone hydrogel contact lenses worn on a continuous-wear basis has been evaluated only recently. This article summarizes the recent research data on extended-wear silicone hydrogel lenses and discusses the challenges of early evaluations of silicone hydrogel lens safety. Finally, the relevance of this information is discussed to practitioners and contact lens wearers making choices about the risks and benefits of different products and how they are used.

Multi-centre evaluation of two daily disposable contact lenses

Purpose 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). Methods 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 −6.00D. 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. Results 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). Conclusion Subjective and objective clinical performance differences between two commonly used daily disposable lenses highlight that, although both lenses may be considered as clinically acceptable, these lenses should not be regarded as interchangeable.

Acanthamoeba keratitis associated with misuse of daily disposable contact lenses

Purpose To report a case of Acanthamoeba keratitis that occurred in a daily disposable contact lens wearer. Method Case report. Results A 70-year-old gentleman presented to eye casualty with a red left eye with reduced vision and corneal epithelial changes. Acanthamoeba keratitis was not suspected initially as he was a daily disposable contact lens wearer. This led to a delay of 17 days in initiating treatment. He responded well to topical polyhexamethylene biguanide and propamidine and made a full recovery. Conclusion Acanthamoeba keratitis can occur in patients who reuse daily disposable contact lenses. A diagnosis of Acanthamoeba keratitis can be difficult to make and should be considered in all patients who wear contact lenses, including daily disposable lenses. All patients who wear daily disposable contact lenses should be reminded that the benefits of this modality of contact lens are only possible if the lenses are worn once and thrown away.

Drying methods for XPS analysis of PureVision?, FocusS Night&amp;Day? and conventional hydrogel contact lenses

The surface composition of hydrogel contact lenses that contain silicon-based monomers, PureVision™ (balafilcon A) and Focus ® Night&Day™ (lotrafilcon A), were investigated by X-ray photoelectron spectroscopy (XPS). Conventional and daily disposable hydrogel lenses based on hydroxyethyl methacrylate (HEMA) were also studied, with the commonly prescribed 1-day Acuvue ® lens (etafilcon A) used as a control. All the lenses were pre-washed and dehydrated by three different methods, including drying in air, drying in nitrogen or freezing with subsequent freeze-drying, before the XPS analysis. The lenses dried in air had more impurities on the surface, and the lenses that were freeze-dried lost transparency, suggesting that drying lenses in nitrogen is the preferred preparation method for XPS analysis. Surface compositions for all lens materials were obtained and this data can be used as a control/base-value for future analysis of the interactions of soft contact lens materials with chemicals such as drugs or tear components.