Low-Level Laser Light Effects—Long-Term Effects

Abstract

Although present laser safety standards are based on an adequate data base for acute viewing situations, they are limited in predicting the type of change in visual function that might be induced from prolonged or repetitive viewing of laser sources. Viewing requirements in holography, laser display systems, and, in general, repeated exposure to low levels of laser radiation require a more complete data base for optimizing the environmental protection of individuals who will be required to work in such environments. In these studies, we have simulated very low-level radiation environments and determined the effects of repetitive prolonged exposure on the visual function of the Rhesus. Our data suggest that prolonged viewing of such sources, even though they are well below present laser safety standards, can produce permanent changes in visual processes that underlie normal human day (photopic) and night (scotopic) vision, although preliminary studies of morphology have shown no morphological correlate. The coherency of laser light is implicated as a significant factor in inducing these effects. It is recommended that individuals required to work in these situations be frequently evaluated for changes in visual function by presently available clinical instruments for assessment of visual function. Further confirmation of these studies will determine the impact of these research findings on present laser safety standards.