Differences Between Contact Lenses and Spectacle Wear Based On Mean Blink Rate and Relative Ocular Comfort Evaluated And Discerned In A Low Humidity Dry Eye Chamber (DEC) Model

Abstract

Purpose: : To evaluate lotrafilcon A and comfilcon A contact lenses (CL) compared to spectacles on blink rate and relative ocular comfort when exposed to the DEC Model.

Methods: : The DEC is a well-controlled, safe and effective model that maintains low relative humidity (≤10%) which mimics arid regions/dry indoor conditions. Twenty-nine CL wearers were randomized to 1 of 3 treatment sequences (lotrafilcon A, comfilcon A, spectacles) in a three-way, cross-over design, and exposed to the DEC. At each visit, subjects wore the assigned treatment for at least 6 hrs prior to entering the DEC for 90mins and remained in clinic 30min post-exit. Blink rate was defined as the number of blinks in one min with a mean of 3 measures taken consecutively. Ocular comfort scores on customized visual analog scale , higher scores equated to better comfort, were collected pre-, during, and 30mins post- DEC.

Results: : Blink rate was indistinguishable between 3 treatment groups after 6hrs of wear, but upon exposure to the DEC for 75min, there was an increase in blink rate for contact lenses when compared to spectacles: lotrafilcon A (p= 0.0066) and comfilcon A (p= 0.0295). Subjects wearing lotrafilcon A had the largest increase in blink rate. At 30mins post-DEC , blink rate returned to almost baseline measures. Ocular comfort scores were also similar for all treatment groups after 6hrs. Following exposure to DEC, all treatment groups reported a decrease in comfort. Subjects wearing lotrafilcon A reported the least change in ocular comfort in the DEC (lotrafilcon A vs comfilcon A p=0.0014; lotrafilcon A vs spectacles p=0.0045) and was maintained post-DEC. None of the 3 groups returned to baseline comfort scores after 30min post-DEC.

Conclusions: : Lotrafilcon A and comfilcon A wearing subjects showed a higher blink rate than spectacles while in the DEC. The higher blink rate shown when subjects wore lotrafilcon A may have led to higher comfort scores when compared to comfilcon A. Utilizing the DEC, blink rate and ocular comfort was effective in investigating responses to different wearing conditions (contact lenses and spectacles) that are otherwise not easily differentiated in everyday environments.

Clinical Trial: : http://www.clinicaltrials.gov P-373-C-900

Keywords: contact lens • cornea: tears/tear film/dry eye • spectacle lens