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January 20, 1999

Sunlight Exposure and Cataract—Reply

Author Affiliations

Margaret A.Winker, MDIndividualAuthorPhil B.FontanarosaMD, Senior EditorsIndividualAuthor

JAMA. 1999;281(3):229-230. doi:10-1001/pubs.JAMA-ISSN-0098-7484-281-3-jbk0120

In Reply: Dr Dillon raises an important point about the specificity of the wavelengths that may be cataractogenic. We have investigated the association of cortical cataract with UV-B radiation, because our previous work and that of others suggested an association with UV-B in particular. Moreover, animal studies1,2 also suggested that the maximum efficiency for experimental lens opacities was about 300 nm, extending from 295 to 320 nm, which is the UV-B range. However, there is clearly a need for additional work to determine the contribution of UV-A to cataractogenesis. The reasoning for this should not be cast in the framework of the relative amount of the various wavelengths that reach the lens, as far more visible and infrared radiation reaches the lens than either UV-A or UV-B, but few would argue that these wavelengths have photobiological effects. Nor, in our opinion, has the albedo effect actually been shown to be relevant for lens exposure. Rather, the rationale rests with the presence in human lenses of compounds able to absorb UV-A, and that absorption can produce a damaging reaction that contributes to cataractogenesis. Only 1 epidemiological study has examined markers of UV-A exposure and found no association with cataract,3 but clearly more work is indicated.