Individual variation in the transmission of UVB radiation in the young adult eye

OBJECTIVES: Data obtained mostly from animal models and ex vivo samples show that a small portion of ultraviolet light (UV, 300–400 nm) penetrates the cornea and crystalline lens and impinges on the human retina. UV transmission to the retina appears to be unique to the young and some older pseudophakes. In this study, we determine the variation in UV transmission in a relatively homogenous sample of young adults. METHODS: 42 subjects were tested (M = 19 ± 1.3 years). Absolute thresholds to UV radiation were collected (λmax = 315 nm, 305–325). Macular pigment optical density (MPOD, measured using heterochromatic flicker photometry) and iris color (using a standardized color scale) were also assessed as potential covariates. RESULTS: All of the subjects could detect UV radiation at 315 nm but individual variation was large (over a factor of 30). Higher MPOD and darker iridies were not related to UV sensitivity in this young sample. Males, however, were more sensitive to UV than the females (p<0.05). CONCLUSIONS: The large individual differences in UV reaching the retina of younger individuals suggests equally significant vulnerability to the actinic effects of this highly energetic light.