To investigate the influence of a new ultra-fast light-adaptive spectacle lens on glare discomfort (GD), photostress recovery time (PRT) and on dynamic contrast sensitivity recovery in healthy subjects, in challenging or varying light conditions.
Two separate studies were conducted, one in Spain, one in USA, both using a double-blind cross-over randomized design, comparing the new type of light-adaptive lens [TO_1] with a static clear lens. Study 1 - Ten healthy subjects (average age 28.7 ± 3.4 years) with a spherical equivalent of -1.8 ± 1.8 D (astigmatism < 1D) were pre-trained to control the contrast of a sinusoidal grating with a spatial frequency of 24 cycles/degree placed at 3 m. TO_1 was compared to a clear lens and to a usual photochromic lens TO_2. Subjects were randomly and monocularly exposed to a bright light stimulus (8000 lux) for 30 seconds with either the clear lens, or with the activating TO_1 or TO_2. Then, subjects were transitioned to a dark environment, and contrast sensitivity measures started. The time to recover the first contrast perception after bright light was recorded for each tested lens. Subjects were then searching for their contrast sensitivity threshold dynamically for 100 seconds. Each lens was tested three times. The time required to get the first contrast perception after bright light exposure and the total time required to achieve 80% contrast improvement were computed. Study 2 - 30 participants (M = 19.2 ±1.3 years) were tested. GD was assessed physically, by measuring palpebral fissure size. PRT was measured as the amount of time necessary to regain visual function after an intense (~15% bleach) 5- second exposure to a broadband (emulated sunlight) light stressor.
Study 1 - There was a significant difference in contrast improvement among the three lenses (p<0.001). In dynamic light to dark conditions, TO_1 was 39% faster than clear lens (p<0.01) to recover 80% contrast sensitivity, and 23% faster than TO_2 (p<0.01). The time to recover the first contrast perception was 55% faster with TO_1 compared to the clear lens (p<0.001). The difference between TO_2 and clear lens was not significant (p=0.03). Study 2 - GD was halved (p < 0.001) when participants viewed the stimulus through TO_1 compared to the clear control lens. PRT was also recuced by 40% when using TO_1 (p < 0.001).
The results highlight the potential of ultra-fast light-adaptive lenses to enhance visual comfort and performance in challenging and varying lighting conditions, compared to the traditional static clear lenses. This improved performance, minimize stress and enhances visual function under normal viewing conditions.
Coralie Barrau2, Raul Duarte-Toledo1, Juan Mompeán1, Alba M. Paniagua-Diaz1, Nacer Lakhchaf2, Emmanuel Kobia-Acquah2, Pablo Artal1, Jacob Harth3, Cameron J. Wysocky4, Billy R. Hammond, Jr4, Lisa M. Renzi-Hammond, Annette Hoskin2