Analysis of real-world eye level light exposure through spectacle lens

This study presents a simulation-based methodology for evaluating lens-modulated light exposure across diverse real-world environmental conditions. A total of 987 outdoor light conditions were captured using calibrated spectroradiometers in 12 countries, recording spectral irradiance (280-780 nm, 1-nm resolution) and illuminance without lenses. Conditions varied by geographic region, weather, head inclination, and solar orientation. A lens transmittance model assigned transmittance values based on ambient illuminance and temperature to simulate the illuminance reaching the eye through clear, sun, and light-adaptive lenses. Melanopic equivalent daylight illuminance (EDI) was also computed to assess biologically relevant light exposure. Mean ambient illuminance was 42,561 ± 45,480 lux (range: 266-288,178) and 5934 ± 6738 lux (243-6738 lux) after light-adaptive lens simulation, with significant variations across environmental conditions. High-illuminance exposure (>10,000 lux) decreased from 68% (clear) to 6% (light-adaptive lens), while exposure between 1000 and 10,000 lux increased from 30% to 90%, and low-illuminance (<1000 lux) remained low (1.7% vs 3.1%). Melanopic analysis showed largely preserved melanopic EDI, with only 6% of conditions falling below 250 melanopic EDI. Light-adaptive lens reduced high-intensity light while maintaining moderate daylight levels and melanopic EDI. This methodology provides a more ecologically valid evaluation of lens performance than conventional lab-based testing.