Ex vivo analysis of ketotifen content in an antihistamine-eluting contact lens worn up to 5 hours.

Aim: This study characterized ex vivo release of ketotifen from etafilcon A contact lenses worn over 5 h. Materials & methods: 14 participants, 21 to 59 years, wore lenses with 19 µg ketotifen over 8 visits, for 1 min to 5 h. Residual ketotifen was measured using high-performance liquid chromatography (HPLC) compared with unworn lenses from the same lots to determine percent ketotifen remaining. Results: Residual ketotifen ranged from 16.19 µg ± 0.44 (84.1%) [1 minute] to 0.20 µg ± 0.07 (1.1%) [5 h]. No adverse events or clinically significant biomicroscopy changes were observed. Conclusion: The ketotifen-releasing etafilcon A lenses were well-tolerated with an acceptable safety profile in the population studied. The release of ketotifen from study lenses over 5 h was consistent with a diffusion-controlled system.

This article is about measuring how fast a medication to relieve itchy eyes from allergies is released from contact lenses that are worn for a single day and then discarded. The study showed that the medication is initially released rapidly over the first 15 min of wear and then more slowly over the next 4+ h until almost none remains. This means that people who have itchy eyes from allergies may be able receive their medication by just wearing these contact lenses each day during their allergy season, without having to put in extra eye drops.

Evaluation of corneal staining with an antihistamine-releasing contact lens.

CLINICAL RELEVANCE: Practitioners can be reassured that this antihistamine-releasing contact lens has no additional effect on corneal epithelial integrity. BACKGROUND: To evaluate the effect of an antihistamine-releasing soft contact lens on corneal epithelium integrity when worn on a daily disposable modality for 12 weeks. METHODS: Two clinical trials using the same randomised, double-masked, placebo-controlled, parallel-group design enrolled healthy contact lens wearers. Participants wore either etafilcon A with 0.019 mg ketotifen (test; n = 374) or etafilcon A with no added drug (placebo; n = 186). Assessments were conducted at baseline, 1 week and 4, 8, and 12 weeks. Slit-lamp evaluations of corneal staining (using sodium fluorescein) in all regions of the corneas of both eyes were graded on a 0-4 scale. Data from all randomised participants were analysed. RESULTS: Corneal staining was infrequent and, where present, was mild (Grade 2) or trace (Grade 1). There were no Grade 3 or 4 findings of corneal staining. The overall proportion of findings of Grade 0 corneal staining was 95.86% with the test lens and 95.88% with the placebo lens. The odds of no staining were not statistically different between the test and placebo lenses (Odds Ratio: 0.96, 95% Confidence Intervals: 0.76 to 1.20). There were no serious ocular adverse events or signs of ocular surface medicamentosa. CONCLUSION: Both test and placebo lenses were well tolerated by subjects during the 3 months of wear. The antihistamine-releasing contact lens does not significantly impact corneal epithelial integrity.

CLEAR - Contact lens technologies of the future.

Contact lenses in the future will likely have functions other than correction of refractive error. Lenses designed to control the development of myopia are already commercially available. Contact lenses as drug delivery devices and powered through advancements in nanotechnology will open up further opportunities for unique uses of contact lenses. This review examines the use, or potential use, of contact lenses aside from their role to correct refractive error. Contact lenses can be used to detect systemic and ocular surface diseases, treat and manage various ocular conditions and as devices that can correct presbyopia, control the development of myopia or be used for augmented vision. There is also discussion of new developments in contact lens packaging and storage cases. The use of contact lenses as devices to detect systemic disease has mostly focussed on detecting changes to glucose levels in tears for monitoring diabetic control. Glucose can be detected using changes in colour, fluorescence or generation of electric signals by embedded sensors such as boronic acid, concanavalin A or glucose oxidase. Contact lenses that have gained regulatory approval can measure changes in intraocular pressure to monitor glaucoma by measuring small changes in corneal shape. Challenges include integrating sensors into contact lenses and detecting the signals generated. Various techniques are used to optimise uptake and release of the drugs to the ocular surface to treat diseases such as dry eye, glaucoma, infection and allergy. Contact lenses that either mechanically or electronically change their shape are being investigated for the management of presbyopia. Contact lenses that slow the development of myopia are based upon incorporating concentric rings of plus power, peripheral optical zone(s) with add power or non-monotonic variations in power. Various forms of these lenses have shown a reduction in myopia in clinical trials and are available in various markets.

Management of Ocular Allergy Itch With an Antihistamine-Releasing Contact Lens.

PURPOSE: A contact lens (CL)-based drug delivery system for therapeutic delivery of the antihistamine ketotifen was tested in 2 parallel, conjunctival allergen challenge-based trials. METHODS: Both trials employed the same multicenter, randomized, placebo-controlled protocol. Test lenses were etafilcon A with 0.019 mg ketotifen; control lenses were etafilcon A with no added drug. Subjects were randomized into 3 treatment groups. Group 1 received test lens in one eye and control lens in the contralateral eye; the eye chosen to receive test lens was randomly selected in a 1:1 ratio. Group 2 received test lenses bilaterally, and group 3 received control lenses bilaterally. Allergen challenges were conducted on 2 separate visits: following lens insertion, the subjects were challenged at 15 minutes (to test onset) and 12 hours (to test duration). The primary endpoint was ocular itching measured using a 0 to 4 scale with half-unit steps. Secondary endpoints included ciliary, conjunctival, and episcleral hyperemia. RESULTS: The mean itching scores were lower for eyes wearing the test lens as compared to those that received control lenses, indicating that the test lens effectively reduced allergic responses. Mean differences in itching were statistically and clinically significant (mean score difference ≥ 1) at both onset and duration for both trials. CONCLUSIONS: This large-scale assessment (n = 244) is the first demonstration of efficacy for CL delivery of a therapeutic for ocular allergy. Results are comparable to direct topical drug delivery and suggest that the lens/ketotifen combination can provide a means of simultaneous vision correction and treatment for CL wearers with ocular allergies.

Corneal thickness results in the Menicon Z 30-day continuous wear and ACUVUE 7-day extended-wear contact lens clinical trial.

PURPOSE: This study was conducted to measure the corneal thickness changes associated with wearing 30-day tisilfocon A (Dk = 163) and 6-day etafilcon A (Dk = 28) contact lenses. The probable cause of the outcomes is discussed. METHODS: Thirty subjects were fitted with Menicon Z rigid gas-permeable (RGP) contact lenses and a control group (n = 30) was fitted with ACUVUE hydrogel lenses, at two study sites. After a 2-week period of daily wear, subjects began prolonged wear. Measurements were performed at the dispensing visit, and then at the 2-week daily wear, the 1-week, 6-month, and 12-month extended- and continuous-wear visits. RESULTS: Repeated measures analysis of covariance was performed on mean corneal thickness. There was a significant increase in corneal thickness in the hydrogel lens extended-wear group compared to the RGP group (P = 0.03). The mean corneal thickness in the ACUVUE group was 2.58% higher at the 2-week daily wear visit, 2.38% higher at the 1-week extended-wear visit, 2.96% higher at the 6-month, and 2.97% higher at the 1-year visit compared to the RGP continuous-wear patients. DISCUSSION: Patients wearing high-Dk RGP contact lenses for continuous wear may have thinner corneas (within the normal thickness range) probably because of minimal hypoxia-induced corneal stromal swelling; RGP-induced reversible corneal epithelial compression; deceased epithelial sloughing; or long-term contact lens-induced keratocyte apoptosis. Patients wearing hydrogel contact lenses for extended wear may have thicker corneas because of hypoxia-induced corneal stromal swelling. Additional evidence of corneal hypoxic stress is seen in the higher prevalence of striae and epithelial microcysts in the hydrogel group and greater variability of corneal thickness measurements in the soft contact lens group in our results.

Corneal endothelial morphology results in the Menicon Z 30-day continuous-wear contact lens clinical trial.

PURPOSE: This evaluation was conducted as part of a protocol entitled Evaluation of the Menicon Z Rigid Gas Permeable Contact Lens for up to 30 Days Extended Wear. The purpose of the protocol was to compare corneal endothelial morphology changes after wearing rigid gas-permeable (RGP) Menicon Z contact lenses, continuously for up to 30 days, with ACUVUE (Johnson & Johnson Vision Care) hydrogel contact lenses, worn for up to 6 nights of extended wear. METHODS: Sixty patients, who were adapted to RGP daily wear and soft contact lens daily wear, were recruited at two study sites. The thirty subjects who wore RGP daily wear lenses were fitted with the Menicon Z (tisilfocon A, oxygen permeablility [Dk] = 163) RGP contact lens comprised the test group. The control group subjects (n = 30 former users of daily wear soft contact lenses) were fitted with ACUVUE (etafilcon A, Dk = 28) hydrogel contact lenses. After a 2-week adaptation period of daily wear, subjects began extended wear. Endothelial imaging was performed at the two study sites in this multicenter study (University Hospitals of Cleveland/Case Western Reserve University Department of Ophthalmology [CWRU] and The Ohio State University [OSU]). The hydrogel lens group was instructed to wear their lenses for 7 days and 6 nights before discarding the lenses and to sleep with no lenses on the seventh night. The RGP group was permitted to wear the lenses for up to 30 days and 29 consecutive nights before removing the lenses for cleaning and overnight soaking. RESULTS: CWRU had 24 patients (12 soft contact lens and 12 rigid contact lens) and OSU had 21 patients (12 soft contact lens and 9 rigid contact lens) who completed the study and were included in the analyses. Patients who were withdrawn from the study at CWRU included one RGP patient dropped out because of pregnancy; one RGP patient developed vascularized limbal keratitis and discomfort; one could not be fitted with a bitoric RGP; two soft lens patients moved from the area, and one dropped out because of dry eyes. At OSU, four patients dropped out due to discomfort (two in each lens type);one moved from the study area; one decided not to participate soon after the consent visit; one had worries of reduced vision at 6 months; one subject's attitude changed prior to the 6 month visit; and one subject was withdrawn for reasons of poor study schedule compliance. CONCLUSION: The Menicon Z lens wearers in this study did not show significant endothelial cell morphology changes after 1 year of nearly continuous contact lens wear. This finding is particularly important considering the RGP wearers in this study were older by a average of 10 years (mean age approximately 40) and had worn their contact lenses an average of almost 10 years longer than the soft contact lens wearers.