Effects of prolonged exposure of rabbit retina to low-intensity light.

Rabbit's eyes were exposed to various levels of measured illumination for four hours. Two sources with different spectral content were compared for their ability to cause retinal damage. The damage was assessed by ophthalmoscopy, electroretinography, and histology. The threshold for minimal detectable damage with a broad-spectrum source occurred around 0.045 watt per square centimeter. A monochromatic source at 514.5 nm. produced damage at one fifth this power level. When the tivo sources were matched by electroretinography for visual efficiency in the rabbit, the thresholds for damage were approximately equal. This shows that the visible portion of the spectrum is primarily responsible for retinal damage under these conditions.