Light-induced retinal changes observed with high-resolution autofluorescence imaging of the retinal pigment epithelium.
OBJECTIVE
Autofluorescence fundus imaging using an adaptive optics scanning laser ophthalmoscope (AOSLO) allows for imaging of individual retinal pigment epithelial (RPE) cells in vivo. In this study, the potential of retinal damage was investigated by using radiant exposure levels that are 2 to 150 times those used for routine imaging.


METHODS
Macaque retinas were imaged in vivo with a fluorescence AOSLO. The retina was exposed to 568- or 830-nm light for 15 minutes at various intensities over a square (1/2) degrees per side. Pre- and immediate postexposure images of the photoreceptors and RPE cells were taken over a 2 degrees field. Long-term AOSLO imaging was performed intermittently from 5 to 165 days after exposure. Exposures delivered over a uniform field were also investigated.


RESULTS
Exposures to 568-nm light caused an immediate decrease in autofluorescence of RPE cells. Follow-up imaging revealed either full recovery of autofluorescence or long-term damage in the RPE cells at the exposure. The outcomes of AOSLO exposures and uniform field exposures of equal average power were not significantly different. No effects from 830-nm exposures were observed.


CONCLUSIONS
The study revealed a novel change in RPE autofluorescence induced by 568-nm light exposure. Retinal damage occurred as a direct result of total average power, independent of the light-delivery


METHODS
Because the exposures were near or below permissible levels in laser safety standards, these results suggest that caution should be used with exposure of the retina to visible light and that the safety standards should be re-evaluated for these exposure conditions.
Morgan
Jessica I W
JI
Center for Visual Science, University of Rochester, Rochester, New York 14627, USA. jmorgan@cvs.rochester.edu
Hunter
Jennifer J
JJ
Masella
Benjamin
B
Wolfe
Robert
R
Gray
Daniel C
DC
Merigan
William H
WH
Delori
François C
FC
Williams
David R
DR
D000818:Animals; D005451:Fluorescein Angiography; D005453:Fluorescence; D008027:Light / Q000009:adverse effects*; D008062:Lipofuscin / Q000378:metabolism*; D008252:Macaca fascicularis; D008254:Macaca nemestrina; D008297:Male; D009887:Ophthalmoscopy / Q000379:methods; D010857:Pigment Epithelium of Eye / Q000378:metabolism* / Q000473:pathology; D011833:Radiation Injuries, Experimental / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism*; D012160:Retina / Q000473:pathology / Q000528:radiation effects*; D012162:Retinal Degeneration / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism*
D008062:Lipofuscin