[Determination of retinal illumination from operating microscopes and assessment of risk].

The retinal illumination from 5 popular operating microscopes was determined with the authors' method to reveal that the intensity of light differed very significantly between brightness adjustments. With dilated pupil and clear media, the power of illumination on the retina was 0.072-0.233 W/cm2 at maximum brightness and 0.042-0.084 W/cm2 at medium brightness, and the safety time limits for application were 22.49s for the former and 50.38s for the latter to avoid retinal damages.