potential hazards to the eyes of human observers. We will first review the different radiation hazards to human eyes which have been revealed by research, and briefly discuss the development of maximum exposure level safety standards. Then we will calculate the energies to which eyes might be exposed by the SPS and evaluate them in terms of the safety standards. 3 .0 Optical Hazards from Non-ionizing Radiation Although the solar spectrum filtered by the earth's atmosphere contains large quantities of ultraviolet and infrared as well as visible energy, the relatively brief exposures obtained from elements of the SPS preclude concern with the ultraviolet which sun-burns the surrounding tissues of the eye (the conjunctiva) and damages the cornea and lens, but only in unreasonably large doses for the present concern. The visible and infra-red portions of the solar spectrum (above 400 nm) damage the lens and retina. The infra-red (750-1100 nm) although it may contribute to retinal burns, is largely dangerous to the lens of the eye, which absorbs a large protion of this energy producing irreversible opacities called glass-blower's cataract. Again, these changes require very long, repeated exposures and therefore may be dismissed as a hazard from the SPS. This leaves the retinal injuries as the major concern for the SPS. There are three kinds of retinal hazards from non-ionizing radiation: thermal burns, photochemical lesions and color-blinding lesions. The thermal burn is a focal lesion, visible by ophthalmoscopy within several hours of exposure, which has been extensively investigated from the earliest days of nuclear weapon testing. It results from viewing the nuclear fireball without protection and also from accidental exposure to laser beams. It is characterized by a localized steam explosion in the retina at the highest energy levels and by coagulation of protein in the retinal pigment epithelium with associated Isos of the adjacent photoreceptors. Controlled retinal burns are commonly used as a treatment for
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