Measurement of ocular ultraviolet radiation(UVR) exposure by dummy-type mannequin dosimetry system for proposing ocular UV index

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Ocular ultraviolet(UV) exposure was measured by a mannequin dosimetry system and its correlation with UV index(UVI) was examined. There was good correlation between UVI and UV exposure to the top of head. When facing toward the sun, ocular UV-B exposure was 8-16% of ocular UV-AB exposure. The ratio of UV-B to UV-AB was relatively low in the morning and the evening, and was highest at noon. When facing away from the sun, the intensity of ocular UV-B exposure was one fourth of that when facing towards the sun in the morning and the evening, and 60% of that at noon. Since UV-B radiation has high scattering property, UV-B exposure is high even at noon. UV-B exposure measured by UV sensor at the top of the head and UVI showed good correlation. However, ocular UV exposure was relatively low when UVI was high, and when UVI was low, ocular exposure was relatively high, showing no significant relationship between the UVI and UV exposure to eyes and the need for ocular UVI to refer to ocular UV exposure. Ocular UV-B exposure when on a snow covered surface was several fold that when on asphalt despite UVI being the same. Since ocular UV exposure is greatly affected by reflected light in the ambient environment, the ocular UVI should be modified to reflect the surface environment such as snow, water and sand. Ocular UV protection in order of effectiveness was : sunglasses> eyeglasses> hat> sunshade Umbrella. In addition, the shape and color of a protector affected its efficacy, and its effectiveness depended on UVI and solar altitude. There was no difference in ocular UV exposure between different latitudes under the same solar altitude.