Calculating Solar Ultraviolet Irradiation Of The Human Cornea And Corresponding Required Sunglass Lens Transmittances

Herbert L. Hoover; Serge G. Marsaud

doi:10.1117/12.952465

9 May 1986 Calculating Solar Ultraviolet Irradiation Of The Human Cornea And Corresponding Required Sunglass Lens Transmittances

Herbert L. Hoover, Serge G. Marsaud

Author Affiliations +

Proceedings Volume 0601, Ophthalmic Optics; (1986) https://doi.org/10.1117/12.952465
Event: 1985 International Technical Symposium/Europe, 1985, Cannes, France

Abstract

Tinted ophthalmic lenses are used primarily for eye comfort in a brightly lit environment. An ancillary benefit is the attenuation of ultraviolet radiation. Some national product standards specify quantitative limits for ultraviolet transmittances. Such limits ought to be founded on quantitative estimates of solar irradiances of ocular tissues, with actinic effectiveness taken into account. We use the equations of Green and coworkers for direct and diffuse solar irradiance at the earth's surface to calculate average sky and ground spectral radiances. We use the geometric factors derived by us for the coupling of radiation from these sources to the human cornea. Actinically weighted corneal spectral irradiances integrated over wavelength and time yield peak irradiances and accumulated exposure doses that are compared with recommended exposure limits. This provides the maximal effective ultraviolet transmittances of tinted ophthalmic lenses such that these exposure limits will not be exceeded in the selected exposure environment. The influences on corneal irradiation of such exposure parameters as solar zenith angle, altitude of the exposure site, characteristics of atmospheric aerosols, and ground reflectances are illustrated. The relationships between the effective transmittance (which is a function of the environmental radiation and any actinicweighting function) and readily determined characteristics of the lens itself, viz., its mean transmittance, and a selected spectral transmittance, are derived for three lens transmittance curves. Limits of lens transmittance for the UV-B and UV-A wavelength regions are presented for several representative exposure sites in Europe and the U.S.A.

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Herbert L. Hoover and Serge G. Marsaud "Calculating Solar Ultraviolet Irradiation Of The Human Cornea And Corresponding Required Sunglass Lens Transmittances", Proc. SPIE 0601, Ophthalmic Optics, (9 May 1986); https://doi.org/10.1117/12.952465

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