Abstract
Using adaptive optics scanning laser ophthalmoscopy and autofluorescence imaging, we recently described novel retinal changes caused by visible light exposures in the macaque retina in vivo. Specifically, we observed an immediate decrease in the autofluorescence intensity of the retinal pigment epithelial (RPE) cells at the exposure location, followed by long-term full recovery or permanent retinal damage. Here, in macaque retina in vivo, we investigate the relationship between the magnitude of the decrease in autofluorescence intensity and exposure average power and duration. The retina was exposed to 568nm light of various intensities (up to 150uW) and durations (up to 15 minutes) over a square area, ½deg visual angle per side. Pre- and post-exposure images of the photoreceptors and RPE cells were taken with a 2deg field of view. The exposures caused an immediate decrease in the autofluorescence intensity, relative to the average power and duration of each exposure. The reduced autofluorescence was transient, but occurred at light levels well below the ANSI standard. Since the mechanism causing the decrease in autofluorescence intensity is currently unknown, it remains unclear whether these effects are detrimental to retinal health. Until these changes are fully understood, these results suggest using caution with retinal light exposures.