A contra-lateral comparison of the visual effects of a photochromic vs. non-photochromic contact lens

Abstract

To compare the effects of a photochromic contact lens vs. a non-photochromic control lens on visual function. Methods: A subject-masked, prospective contralateral eye design was used. Sixty-one subjects were enroled based on age (using a 2:1 allocation ratio for ages 18-39 and 40-65 years, respectively). The study lenses were senofilcon A with photochromic additive (Test) that filtered over the entire lens, compared to a non-photochromic Control with no tint. The Test lens was partially activated during testing with a steady-state transmittance of approximately 62%. Eligible subjects were tested using both study lenses, with Test and Control lens randomized by eye. Five visual function outcomes were tested: photostress recovery (PSR), glare disability (GD), glare discomfort (GDC), chromatic contrast (CC) and vernier acuity (VA). Iris colour and macular pigment density were assessed as control variables. PSR was measured as the time needed to recover sight of a target after an intense xenon flash exposure; GD was evaluated as the energy needed to veil a central target by a surrounding xenon annulus; GDC was measured using bio-imaging of the squint response and by self-report using a 9-item Likert scale; CC was measured as thresholds for a yellow grating target superposed on a 460-nm background; VA was determined by measuring vernier offsets of light lines through apertures. Results: Based on our stimulus conditions, PSR was 43% faster using the Test vs. the Control. The eye wearing the Test had 38% less squint (GDC) compared to the Control. GD was improved by 36% in the Test vs. Control and CC was enhanced by 48% with the Test. There was no significant difference in VA. Conclusions: There was a beneficial influence on visual function when comparing the photochromic with the non-photochromic contact lens. This benefit was seen specifically with respect to PRT, GDC, GD and CC thresholds.

The Effect of a Photochromic Contact Lens on Visual Function Indoors: A Randomized, Controlled Trial

“…These specific visual functions were selected based on our recent studies using the same apparatus with an activated photochromic contact lens. All tests used the same apparatus, modified for each parameter (for details, see Renzi-Hammond et al 1 ). The glare source (annulus/disk; simulating noon-day sunlight) and the visual target were produced by a 1000-W xenon arc point source lamp, with a modified housing that allowed dual-channel exit (Newport Optics, Irvine, CA).…”

“…A recent empirical study has shown that the lens demonstrates reduced visual issues, such as glare disability and discomfort, while speeding photostress recovery. 1 Renzi-Hammond et al 1 used a violet activator to test the lens as it would be expected to be darkened in a typical outdoor situation. The photochromic lenses, however, are meant to be worn inside as well.…”

“…In this study, we used a contralateral subject-masked design to compare visual effects across a nonphotochromic and minimally activated photochromic lens. We selected a range of variables that were consistent with those we previously measured on a different sample with the photochromic activated using a violet activator 1 : photostress recovery time, glare disability, glare discomfort, and chromatic contrast.…”

Lens fitting and subjective acceptance of senofilcon A with photochromic additive on a neophyte population

“…Photochromic contact lenses can significantly reduce objective measures of squinting compared to clear contact lenses [3]. In a randomized, contralateral crossover trial, investigators measured changes in patients' palpebral fissure height 1 s into a 5 s exposure to a 1000 W xenon arc point source lamp.…”

“…The U.S. Food and Drug Administration approved the Test lens in April 2018 [2], and studies have investigated aspects of its performance, including its effect on visual recovery, squint response, and driving [3,4]. Nonetheless, the literature is yet to report the subjective vision experience of patients fitted with this lens.…”