Are ophthalmologists exposing their patients to dangerous light levels?

T:here appears in this issue an article by Calkins and Hochheimer (p. 1009) which presents evidence that light exposures from ophthalmoscopes, slit lamps, and overhead surgical lamps can present a hazard to the retinas of patients. Other studies have appeared recently which also indicate that ophthalmological diagnostic and treatment devices may be hazardous, on the basis of animal exposure evaluated against light safety standards. The growing concern over ophthalmological devices has led in the past year (1) to the formation of a working group of the National Research Council Vision Committee to look into these hazards (Myron Wolbarsht discusses it in a Letter to the Editor, p. 1124), (2) to a session on ophthalmic exposures in a conference on applied vision sponsored by the National Academy of Sciences, and (3) to a special conference sponsored by the National Eye Institute, which I organized. Held in Houston, the conference was attended by about 50 clinicians and basic scientists who discussed intense-light effects on the retina under five headings: (1) potential hazards from specific ophthalmic devices; (2) quantitative dimensions of intense-light damage obtained from animal studies; (3) radiation measurements, and the development of standards; (4) basic research on the role of light in receptor renewal and metabolism; and (5) degenerative retinal disorders and intense-light exposure. An extensive discussion session was also held. The proceedings of the conference will be published as a special issue of Vision Research, which I hope will appear before the end of the year. Among the ophthalmological procedures or devices which either exceed the existing safety standards or are on the borderline are intraocular fiberoptic illuminators used in vitreous surgery, photocoagulators (to nonfocal regions), fluorescein angiography, fundus photography, and indirect ophthalmoscopy. The safety evaluations are not straightforward because the standards were developed primarily for coherent light sources and have only begun to be adapted to extended, incoherent light sources such as used in ophthalmic devices. The standards are also cumbersome and difficult to use, although recently the American Congress of Government Industrial Hygienists has published simplified versions which can be applied more easily. The experiments on animals which have directly applied the diagnostic and treatment devices have assumed steady fixation of the light on the retina, which is probably unrealistic, and have often chosen the highest intensities, which may not always be used in practice. So the results to date on the specific devices are still debatable. The research on animals which serves as