Change in the geometry of positive- and negative-powered soft contact lenses during wear.

Contact lens wear causes mutual interactions between the ocular surface and the lens, which may affect comfort as well as vision. The aim of this study was to examine deformations in modern positive- and negative-powered silicone hydrogel soft contact lenses (SiH SCLs) after 7 days of continuous wear. This pre-post interventional study included 64 eyes: 42 eyes with myopia of -3.00 D and 22 eyes with hyperopia of +3.00 D. All patients underwent general ophthalmic examination, corneal topography/tomography, total corneal and epithelial thickness mapping, and specular microscopy before and after the wearing period. SiH SCLs made of senofilcon A were worn continuously for 7 days on all eligible eyes. The geometry of the new and used lenses was measured 3 to 6 minutes after removal in two perpendicular planes using a custom-made swept source optical coherence tomography (SS-OCT) system for in vitro measurements. The anterior and posterior radii of curvature decreased in -3.00 D lenses in two perpendicular planes. This effect correlated significantly with average keratometry of the cornea. Sagittal lens height was lower in +3.00 D lens after wear, which correlated moderately with the corneal sagittal height. A significant decrease in central corneal epithelial thickness was observed after wearing +3.0 D lenses. In conclusion, SiH SCLs made of senofilcon A undergo minor deformations after 7-day continuous wear. Geometry modifications are different for -3.00 D and +3.00 D lenses, and they imitate the shape of the anterior eye surface. These geometric changes are accompanied by a decrease in the central thickness of corneal epithelium after +3.00 D lens wear.

Comparison of Extended Depth-of-Focus Prototype Contact Lenses With the 1-Day ACUVUE MOIST MULTIFOCAL After One Week of Wear.

OBJECTIVES: To compare visual performance of extended depth-of-focus (EDOF) prototypes with a new, center-near, commercial, multifocal contact lens. METHODS: Presbyopic participants (n=57) wore 1-Day ACUVUE MOIST MULTIFOCAL (1DAMM) and an EDOF prototype for one week in a double-masked, prospective, cross-over, randomized clinical trial. Manufacturers' guide was used to select the first pair of lens to be fit based on subjective distance refraction and near addition. After one week, high- and low-contrast visual acuities were measured at distance (6 m), intermediate (70 cm) and near (50 and 40 cm), and stereopsis at 40 cm. Subjective performance was assessed on a 1 to 10 numeric rating scale for vision clarity and lack of ghosting at distance, intermediate and near, vision stability, haloes at night time, overall vision satisfaction, and ocular comfort. Linear mixed models were used for analysis and the level of significance was set at 5%. RESULTS: 1DAMM was not significantly different from EDOF for high- or low-contrast visual acuity at any distance, or for stereopsis. Subjectively, EDOF was significantly better than 1DAMM for vision clarity at intermediate (P=0.033) and near (P<0.001), overall lack of ghosting (P=0.012), vision stability (P=0.004), and overall vision satisfaction (P=0.005). For all other subjective variables, there were no differences between EDOF and 1DAMM (P>0.05). CONCLUSIONS: EDOF prototype lenses offer improvements over the newly marketed 1DAMM lenses for several subjective variables.

Are silicone hydrogel contact lenses more comfortable than hydrogel contact lenses?

The current literature review was intended to investigate whether the use of silicone hydrogel contact lenses has resulted in improved comfort compared with that of hydrogel contact lenses when both are used for daily wear. The conclusion reached is that silicone hydrogel contact lenses, which were initially developed to eliminate hypoxia during overnight wear, have not significantly improved comfort compared with the comfort achieved with hydrogel contact lenses when worn on a daily wear basis, even though a body of the published literature would suggest to the contrary. A careful review and consideration of the literature demonstrates that the relative comfort achieved with the two types of contact lenses is in fact highly dependent on the study methodology: Although refitting studies have concluded enhanced comfort with silicone hydrogels, the more robust study designs involving concurrent controls and masking were not able to show a difference, and some even concluded an inferior performance. Evidence-based review has however clearly demonstrated that comfort cannot be considered in isolation but is contact lens specific and depends on the material surface and bulk properties, lens design characteristics, and modality of use of the contact lens, and may also be significantly influenced by the replacement frequency and interaction with any lens care system that may be used.

The future of silicone hydrogels.

Significant advances during the past decade in silicone hydrogel lenses have made them the primary mode for new contact lens wear. Their dominance in the market place is driven largely by the elimination of structural and physiological changes induced by contact lens-induced hypoxia, as exemplified especially by the reduction in limbal redness. However, end-of-day dryness and discomfort still drives many to discontinue lens wear. Evidence also indicates that the rate of serious adverse events, such as microbial keratitis, have not been impacted with the use of silicone hydrogel lenses. Moreover, there are additional challenges relating to 'corneal staining' and corneal infiltrates associated with the incompatibility of lens care product with contact lens polymers. On the other hand, technological advances enabled by the high oxygen platform present opportunities for expanding the use of contact lenses in areas that have exhibited limited uptake in the past such as astigmatism, presbyopia, and importantly myopia control. The challenges and opportunities facing the field will be discussed.

Characterization of patients who report compliant and non-compliant overnight wear of soft contact lenses.

PURPOSE: To describe compliant and non-compliant overnight wear (EW) of soft contact lenses from a large observational study. METHODS: A retrospective chart review of 3211 SCL patients with known EW status (aged 8-33yrs, SCL power +8.00 to -12.00D) captured data from 10,516 clinical visits (2006-2009). Status of EW was either daily wear (DW), compliant EW (overnight wear of US Food & Drug Administration (US FDA) EW-approved lenses), non-compliant EW (overnight wear of DW-approved lenses). The effect of demographic and clinical characteristics on the likelihood of reporting EW was examined using logistic regression. Additionally, the effect of these same characteristics on the likelihood of non-compliant EW was assessed with logistic models. RESULTS: Eight-hundred and eight patients (25.2%) reported EW. Non-compliant EW was reported by 6% of wearers (13 hydrogel, 2 silicone hydrogel brands) In multivariate models, patient age and lens replacement schedule were significant factors for EW (vs. DW) and for non-compliant (vs. compliant) EW (p<0.0001). Other factors significantly related to EW were gender, smoking, lens material, sphere power, and years of CL wear (p≤0.007, all). CONCLUSIONS: Young people (ages 18-25yrs), males, smokers, myopes, silicone hydrogel lens wearers and patients with >1yr of CL wear were significantly more likely to report EW. Non-compliant EW occurred often in young people and daily disposable wearers, though many brands had non-compliant EW use. Understanding who is likely to wear EW and non-compliant EW will help clinicians pointedly counsel patients more at risk on best practices with EW.

Postmarket surveillance of Menicon Z rigid gas-permeable contact lenses for up to 30 days continuous wear in the United States.

OBJECTIVES: To evaluate the incidence of microbial keratitis associated with the use of the Menicon Z rigid gas-permeable (RGP) contact lenses (CLs) for up to 30 days continuous wear (CW). For this study, CW was defined as wearing CLs in an extended-wear modality with an average wearing time of 22 days or more. Microbial keratitis was the sole endpoint of the study safety evaluation. METHODS: Subjects who were interested in RGP lens CW were recruited for the study through 33 investigational practices. To be eligible for the study, subjects must have worn the Menicon Z lens for CW for at least 1.5 months with an average CW time of 22 days or more. Eligible wearers were then contacted at 6-month intervals for up to 24 months after enrollment to determine their typical wearing schedules and continuance of wear and to detect any problems that would be indicative of microbial keratitis. Discontinuation from the study was defined as a discontinuation of contact with or CL wear by the study participants. Study volunteers could be discontinued from the study at 6, 12, 18, or 24 months if they could not be contacted (lost to follow-up); if they were not wearing their CL for CW; or at their own request. Wearing time data collected for individuals discontinued from the study was included in the wearing time analysis. RESULTS: The study population included 507 participants, of whom 173 had discontinued by the end of study at 24 months. Lack of 22 days or more of CW was the most frequently cited reason for discontinuation and accounted for 121 of the 173 subject discontinuations. Lost to follow-up, study participant choice, and other reasons accounted for the remaining 52 subject discontinuations. Of the reported wearing times over the duration of the study, 1,275 of the 1,527 contacts resulted in reported wearing times of 22 days or more of CW. There were no findings of microbial keratitis during the study. Overall, there was a low reported rate of complications for the enrolled study participants. CONCLUSIONS: On the basis of this study, CW of the Menicon Z hyper-Dk/t RGP lens provides a safe and full-time vision correction alternative for patients who can adapt to RGP lens wear.

Comfort-enhanced daily disposable contact lens reduces symptoms among weekly/monthly wear patients.

OBJECTIVES: The primary objective of this trial was to explore the extent to which common contact lens-related symptoms may be improved among symptomatic daily wear contact lens wearers who habitually replaced their lenses at intervals of 1 to 4 weeks when fitted with DAILIES AquaComfort Plus for daily disposable, daily wear. Primary variables were frequency and severity of tired eyes, irritated eyes, lens awareness, blurred vision, redness, discomfort, deposits, and dryness. METHODS: Eight sites, investigators enrolled 83 subjects who reported two or more of the symptoms with frequency of often or always. A sample size estimate required 60 subjects for 80% power, two-sided alpha = 0.05. Subjects were dispensed for 4 weeks of bilateral lens wear. Follow-up visits were at 2 and 4 weeks; data were collected by telephone surveys at 1 and 3 weeks. RESULTS: Eighty-one subjects completed the trial. Statistically significant improvements in symptom frequency were found for the symptoms of tired eyes (P<0.001), irritated eyes (P<0.001), blurred vision (P<0.001), redness (P<0.001), discomfort (P=0.024), deposits/lens needs cleaning (P<0.001), and dryness (P<0.001). Statistically significant improvements in symptom severity were found for tired eyes (P<0.001), irritated eyes (P<0.001), blurred vision (P<0.001), redness (P<0.001), discomfort (P=0.037), deposits/lens needs cleaning (P<0.001), and dryness (P<0.001). Biomicroscopy signs of limbal redness, bulbar redness, and conjunctival staining showed statistically significant improvements at 2 weeks (P=0.02, 0.01, and 0.035) and 4 weeks (P< or =0.001, 0.012, and 0.008). CONCLUSIONS: A range of common symptoms can be reduced and biomicroscopy signs can be improved with a comfort-enhanced daily disposable, daily wear lens, thus providing benefits that patients can experience and eye care practitioners can appreciate.

Clinical investigation of asmofilcon a silicone hydrogel lenses.

PURPOSE: To investigate the clinical and subjective performance of asmofilcon A, a new third generation silicone hydrogel contact lens during 6-night extended wear (EW) over 6 months. METHODS: A prospective, randomized, single-masked study was conducted. Sixty experienced daily wear soft contact lens wearers were randomly assigned to wear either asmofilcon A or senofilcon A contact lenses bilaterally for 6 months on an EW basis. Evaluations were conducted at contact lens delivery and after 1 week, 4 weeks, 3 and 6 months of EW. RESULTS: Fifty subjects (83%) successfully completed the study. Two subjects experienced adverse events; one unilateral red eye with asmofilcon A and one asymptomatic infiltrate with senofilcon A. There were no significant differences in high or low contrast distance visual acuity between asmofilcon A and senofilcon A; however, low contrast distance visual acuity decreased significantly over time with both contact lens types (p < 0.05). The two lens types did not vary significantly with respect to any of the objective and subjective measures assessed (p > 0.05). Superior palpebral conjunctival injection showed a statistically significant increase over time with both lens types (p < 0.05). Both lens types were rated highly with respect to overall comfort, with subjects reporting 14 or 15 h of comfortable lens wearing time per day at each of the study visits (p > 0.05). Overall satisfaction ratings were also very high at all visits, with median scores of 95 (86 to 99) for asmofilcon A and 90 (85 to 96) for senofilcon A at 6 months (p > 0.05). CONCLUSIONS: Over 6 months of EW, the asmofilcon A contact lens performed in a similar manner to senofilcon A with respect to visual acuity, ocular health, and contact lens performance measures. Longer-term EW studies are required to investigate the changes over time observed with both lens types.

Hydrogel lens comfort in challenging environments and the effect of refitting with silicone hydrogel lenses.

PURPOSE: The purpose of this analysis was to measure the proportion of soft contact lens wearers who wear lenses in challenging environments and to evaluate their resulting comfort in those conditions. A second objective was to determine whether refitting with silicone hydrogel lenses affects lens comfort among subjects who wear lenses in these environments. METHODS: Baseline data were collected from 496 hydrogel soft lens wearers on the frequency of use of contact lenses and the associated comfort in 12 challenging environments. Subjects were then refit into second generation silicone hydrogel lenses: senofilcon A (n = 228), galyfilcon A (n = 132), or lotrafilcon B (n = 136). Comfort responses were compared for subjects who "always" or "frequently" used lenses in the queried environments after 2 weeks of silicone hydrogel daily lens wear. RESULTS: More than 80% of subjects used habitual lenses "always" or "frequently" while reading, sitting in an air-conditioned or heated car, using a computer and while driving at night. Less than 40% used lenses "always" or "frequently" while riding in an airplane, at high altitudes, or while napping or sleeping. The least comfortable environments were in dusty, polluted or smoky environments (30% comfortable), and the most comfortable were while reading and using a computer. After 2 weeks use of senofilcon A and galyfilcon A lenses, comfort in all environments improved significantly (Wilcoxon signed rank) except for using a computer with galyfilcon A. After 2 weeks with lotrafilcon B lenses, there was improved comfort while using lenses in all environments except driving at night, using a computer and sitting in an air-conditioned or heated car (p < 0.04, Wilcoxon signed rank). CONCLUSIONS: Daily wear contact lens wearers limit use of lenses during air travel or while napping. Use of daily wear silicone hydrogel lenses improved comfort significantly in most environments, allowing subjects to wear them in challenging environments.

Contact lenses: optimal vision--sub-optimal carrier?

The development of silicone hydrogel contact lenses with high oxygen permeabilities is a major step forward in vision correction. This advance in contact lenses material technology provides breakthrough levels of oxygen to the cornea. However, there are still important issues yet to be addressed by researchers, practitioners, and industry. Factors such as adequate correction for all refractive errors, microbial keratitis, comfort, and suitable lens care and lens biocompatibility are discussed from the authors' perspective.

Initial comfort of lotrafilcon A silicone hydrogel contact lenses versus etafilcon A contact lenses for extended wear.

PURPOSE: To compare the initial comfort afforded by silicone hydrogel lenses (lotrafilcon A) versus the comfort afforded by conventional hydrogel lenses (etafilcon A) in extended wear (EW). DESIGN: Prospective, double-masked and randomized controlled trial. METHODS: Lotrafilcon A and etafilcon A contact lenses were eye randomly fitted on an EW basis for 7 days and nights in 20 subjects. A forced-choice subject preference questionnaire was made. Subjects were comfort, dryness, red eye and visual quality after night wear and at the end of the day. Subjective scored satisfaction (scale: 1-5) and lens preference were assessed. RESULTS: Lotrafilcon A proved more comfortable after night wear (60%, CI95% 38-82%) and at the end of the day (70%, CI95% 49-90%) than etafilcon A after night wear (10%, CI95% 0-23%, P<0.05) and at the end of the day (20%, CI95% 2-38%, P<0.05). The feeling of dryness was more marked with etafilcon A after night wear (50%, CI95% 27-72%) and at the end of the day (50%, CI95% 27-72%) than it was with lotrafilcon A (15%, CI95% 0%-31%) after night wear (P>0.05) and at the end of the day (25%, CI95% 5%-44%, P<0.05). General satisfaction with the lotrafilcon A lens was 3.65 points (CI95% 3-4.2) and with etafilcon A 2.95 points (CI95% 2.5-3.3, P<0.05). Eighty percent (CI95% 62%-98%) of subjects preferred lotrafilcon A (P<0.05) for EW. CONCLUSIONS: In EW, lotrafilcon A contact lenses were more comfortable and led to less dryness after night wear and at the end of the day than etafilcon A contact lenses.

Extended wear soft contact lenses: to market or not to market.

1. Today, cosmetic extended wear lenses have numerous aliases; continuous wear, provisional extended wear, and flexible wear, all referring to the same products, but on a relative scale of wearing time. Cosmetic extended wear lenses are elective and differ from the medical necessity of extended wear that few patients require. Refractive surgery has made significant advances in the cosmetic extended wear lens market. 2. Despite growing conservatism, positive marketing kept growing the EW philosophy for almost a decade until the FDA laid down some new rules, including a 1-week maximum for overnight wear. Coincidentally, this mandate came with the advent of the disposable lens in 1989. Since then, 1-week EW with disposable contacts has proved to be a safer modality for cosmetic EW; however, the concern of corneal complications continues to decline the market. 3. Patients risk a microbial ulcerative keratitis secondary to cosmetic EW. If daily wear contact lens options or occasional part-time EW is not amenable to the patient, refer the patient to an experienced refractive surgeon. Today, patients have more healthful vision choices than ever before.

CCLRU standards for success of daily and extended wear contact lenses.

Success in contact lens wear is often judged on the basis of patient "survival" rather than the achievement of satisfactory performance based on specific criteria. In 1971, Sarver and Harris defined a series of standards for successful polymethyl methacrylate (PMMA) lens wear which incorporated criteria for wearing time, comfort, vision, ocular tissue changes, and patient appearance. In this paper we propose a revision of these criteria based on current understanding of the ocular response to contact lens wear. These revised CCLRU (Cornea and Contact Lens Research Unit) standards for success are intended as realistic performance objectives, and can be applied in clinical trials to evaluate and compare the clinical performance of present and future rigid and soft contact lenses, worn for daily and extended wear.

Disposable contact lenses.

Disposable soft contact lenses are an alternative to conventional extended-wear lenses and provide an acceptable margin of safety and convenience for the wearer. The lenses are worn for one to two weeks and then discarded. Buildup of tear film deposits is minimized, and the need for cleaning and disinfecting solutions is eliminated. The long-term safety of disposable contact lenses is unknown.

Legal consequences of the FDA's 7-day extended wear letter.

The U.S. Food and Drug Administration (FDA) recently sent contact lens practitioners a letter advising them that the FDA had asked manufacturers to indicate a maximum recommended wearing time of 7 days for cosmetic extended wear soft contact lenses. This paper discusses the authority of the FDA and the legal consequences of the FDA's "7-day Letter." Congress has authorized the FDA to enact rules, guidelines and recommendations. The 7-day letter does not appear to be any of the above. However, it does have a significant effect on contact lens practitioners' professional responsibilities and legal obligations because the letter has led to changes in product labeling and the standard of care for extended wear patients. Practitioners would be wise to give careful consideration to any deviation from the FDA's recommendation and the provisions of the product labeling. As any deviation will likely impose greater legal responsibility on the practitioner, the special circumstances that justify the deviation should be thoroughly documented in an informed consent agreement.

The FDA role in contact lens development and safety.

The Food and Drug Administration (FDA) exercises a multifaceted role in fulfilling its mission of enforcing the Federal Food, Drug and Cosmetic Act (Act), functioning not only as industry regulator and consumer protector, but also as scientific advisor and consumer educator regarding medical devices, drugs, foods, cosmetics, and veterinary medicine. Medical devices are regulated within the Center for Devices and Radiological Health. Contact lenses are regulated under the authority of the medical device amendments. The Center is responsible for promulgating regulations, publishing guidelines, and developing written guidance in enforcing the Act, and also for guiding manufacturers of medical devices in safe and effective product development. Other components deal with the compliance of manufacturers with the marketing of medical devices within the meaning of the Act, and through labeling requirements of the Act and consumer education and informational activities. As for contact lenses, the process of updating product development regulations and guidelines is an ongoing activity. The most recent version of the Contact Lens Guideline Document, issued in April 1988, contains two major revisions involving preclinical and clinical testing. The first redefines plastics into one materials category, thus reducing testing requirements with respect to animal toxicology studies and other preclinical areas. The second revision restricts clinical testing requirements to allow confirmatory trials in applications for new daily wear lenses. The intention was to maintain the ability of studies to detect major material or design flaws in lenses, thus boosting confidence in their performance while eliminating unnecessary trials.(ABSTRACT TRUNCATED AT 250 WORDS)

[Semi-rigid permeable contact lenses. Our experience with extended wear]. / Verres de contact semi-rigides gaz perméables. Notre expérience en cas d'utilisation prolongée.

In a study concerning 124 eyes, we have considered the frequency of superficial deposits on gas-permeable contact lenses in extended wear. On the whole this is not a serious problem when a regular and complete upkeep is made. The new materials made with fluor have proven to be superior to materials made with silicones.