Sunglasses: calculation for corneal exposure and influx of UV through the pupil

Abstract

UV protection is crucial for sunglasses, and the World Health Organization and the International Commission on Non-Ionizing Radiation Protection have set safe limits for UV radiation exposure. We conducted a study using the SMARTS2 model to calculate solar UV irradiance on a vertical surface simulating sunglasses. The radiant exposure on the eye's surface was calculated for the 280nm-400nm range, following ICNIRP recommendations. Results showed that the tested lens failed to meet the UV-A safe limit, even after the aging process. Incorporating ICNIRP safe limits into standards is necessary for better UV protection. While the importance of UV protection when wearing sunglasses is emphasized, there is a lack of quantification regarding pupil dilation. We estimated pupil diameter and calculated UV influx through the pupil, considering surrounding luminance. Pupil diameter ranged from 2mm to 7.8mm, adjusting to brightness changes. At midday, when the sun is less direct, the pupil is larger. Wearing and not wearing sunglasses exhibited opposite behaviors, highlighting the need to understand how light attenuation affects pupil diameter through transmittance spectra analysis.