Light Damage

The Photopathology and Nature of the Blue Light and Near-UV Retinal Lesions Produced by Lasers and Other Optical Sources

“…The radiant exposure required to produce a minimal lesion was approximately 5 J em -2 for a 100 or 1000 s exposure to 350 and 325 nm, as contrasted with 30 J em -2 for 441-nm blue light. Enough histological data are available now to demonstrate that near-UV lesions differ from blue light lesions in several important respects (Ham et al, 1987). The UV lesion is funduscopically visible immediately after exposure as contrasted to a latent period of 48 h before a minimal blue light lesion appears, and the photoreceptors as well as the RPE are damaged, particularly the cone ellipsoids, which appear to be especially vulnerable, probably because of absorption by the metalloflavoproteins and cytochromes in the mitochondria.…”

“…Continuing their research, Ham et al (1987) exposed the aphakic eye (lens surgically removed) of a rhesus monkey to 325 nm ultraviolet radiation while elevating the arterial blood oxygen level to various P0 2 's (398, 389, 278, and 139 mm Hg). Radiant exposures for threshold damage were reduced from 5.5J cm-2 at normal P0 2 's (75-100 mm Hg) to less than 2 J cm -2 for P0 2 's greater than 300 mm Hg.…”