Solar Ultraviolet Exposure and Absorbed Irradiance of the Cornea and Anterior Chamber/Lens: A Monitoring Model Using Porcine Eyes in a Manikin

Abstract

Solar ultraviolet (UV) radiation is an unavoidable environmental and physical factor that contributes to a variety of eye diseases. Previous studies have mostly focused on the mechanism of eye damage caused by acute UV radiation. However, long-term and low-level day-to-day solar UV irradiance and absorption of UV ocular tissue induce chronic damage, and cumulative exposure over time may lead to age-related oculopathy. This study aimed to monitor the exposure of ocular tissue to sunlight and the amount of incident radiation absorbed. We attempted to simulate the actual natural exposure of representative ocular tissue to solar UV radiation. Therefore, in this study, a dual-detector spectrometer was used to measure the exposure, at a range of solar elevation angles (SEAs), of porcine eyes implanted into a manikin. The study found that the maximum solar UV irradiance exposure of the cornea was one-half the horizontal ambient exposure, while that of the anterior chamber/lens was one-fifth the horizontal ambient exposure. The absorption ratio decreased with increasing wavelength for the cornea and increased with increasing wavelength for the anterior chamber/lens. In conclusion, the study established a monitoring model using porcine eyes and determined the absolute and relative exposure/absorbed UV irradiance of ocular tissue at all SEAs in a context with high ambient solar UV. Furthermore, the study indicated that for individual ocular solar UV exposure, the ratio of absorbed to total exposure to solar UV irradiance varied due to changes in the SEA and sunlight path length throughout the day. These findings provide data on actual exposure and absorbed irradiance for future UV studies and might provide an exposure-based reference for cataractogenesis.