Potential ocular hazards from xenon flashlamps

High radiance optical sources used in fast photocopiers represent a potential hazard to the human retina. Primates (macaque monkeys) were exposed to a prototype flashtube assembly similar to that used in fast photocopiers. One animal trained in a restraint chair to perform a visual task for a major portion of his food was exposed to multiple pulses (1000 pulses daily) from two xenon flashtubes placed 22 cm from the eyes. After sixty daily exposures over a period of three months with pupils dilated to 8 mm or greater, no anomalies were detectable in the retina. Examination for defects with the fundus camera was negative even a year after the exposures. Four additional monkeys (eight eyes) were exposed under anesthesia to insure that repetitive exposures on the retina were coincident. Exposure to two xenon flashtubes, each with 160-J input, did not produce a retinal lesion after 4200 flashes spaced 1.7 s apart. Exposure to a single flashtube with 540-J input produced negative results even after fifty flashes focused on the same retinal site. It was concluded that neither of these optical sources was capable of producing a thermal lesion in the monkey retina. Calculations predict that a photochemical-type retinal lesion is possible but only in extraordinary conditions of exposure which would be extremely unlikely, if not impossible, while viewing a photocopier.