Product Code: ILSC2009_202

Retinal Phototoxicity Observed using High-resolution Autofluorescence Imaging
Authors:
Jennifer J. Hunter, Center for Visual Science, University of Rochester; Rochester NY USA
Jessica I. W. Morgan, Department of Ophthalmology, University of Pennsylvania; Philadelphia PA USA
William H. Merigan, Center for Visual Science, University of Rochester; Rochester NY USA
David R. Williams, Center for Visual Science, University of Rochester; Rochester NY USA
Presented at ILSC 2009

The American National Standards Institute (ANSI) provides guidelines for the safe use of lasers from which maximum permissible exposures of laser light are calculated. This standard is used as a limit for ocular light exposures and to assess the safety of retinal imaging experiments. Using in vivo adaptive optics scanning laser ophthalmoscopy equipped with fluorescence imaging capabilities, we have observed retinal changes in the macaque retina caused by visible light exposures that are below the ANSI safety standard. Specifically, we observed an immediate decrease in the autofluorescence intensity of the retinal pigment epithelial cells at the exposure location (AF dimming), followed by long-term full recovery or permanent retinal damage. AF dimming was observed with exposure to 488 nm or 568 nm light. We have demonstrated the photochemical nature of AF dimming. Experimental evidence suggests that multiple lipofuscin fluorophores are involved in AF dimming. Since the mechanism causing AF dimming is currently unknown, it remains unclear whether these effects are detrimental to retinal health. Even if AF dimming is not hazardous, our results encourage a re-evaluation of the standards for avoiding photochemical damage from exposures in the middle of the visible spectrum.