Abstract
Purpose :
In most studies, light exposure but also visual comfort, glare reduction and protection, are assessed through self-administered questionnaires, which have been proved not to be accurate enough. We here propose to use recorded data from real life, in terms of light exposure and wearing time of eyewear, to simulate more accurately the light exposure profile of wearers with several filters.
Methods :
Light exposure data and wearing times of clear and sun eyewear were previously collected for 27 participants wearing instrumented frames with spectral light sensors for 17 days in Paris, France. For the first time, those real-life data were combined with the spectral and temporal properties of three configurations of filters: clear lenses, clear + class-3 sun lenses and newly designed photochromic lenses. Light doses were calculated using lens transmission, irradiance and wearing time for all time points.
Results :
The cumulative light exposure of a wearer over the 17-day data collection were 242 J/cm2, 227 J/cm2, and 142 J/cm2 for clear, clear + sun, and photochromic lenses, respectively, considering the real wearing times of clear vs sun lenses.
In low light levels (<1000 lux), the photochromic lens remained non-tinted, with less than 4% deviation in the light dose compared to clear lenses.
Considering all light conditions above 1000 lux, a wearer received 189 J/cm2, 148 J/cm2 and 106 J/cm2 for clear, clear + sun, and photochromic lenses, respectively, showing a better efficacy of photochromic in limiting the light dose reaching the eye. While the wearers spent only an average of 11% of their time above 1000 lux, these, mainly outdoors, represented 70% or more of the total received light dose.
Regarding the dynamics of change between clear and sun lenses, the real-life study revealed that the switching time was 10 min on average.
Conclusions :
Light data and wearing times of eyewear collected in real life can be instrumental to simulate and then better define the efficacy of new ophthalmic filters, from passive solutions (clear/sun) to dynamic ones (photochromic lenses).
Our study underlines the value of light intelligent lenses, for their seamless protective capability. They excelled in minimizing high light levels, with no need to wait for the ultimate point when the wearer is so annoyed by light that he decides to change from clear to sun lenses.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.