Purpose. The benefits and risks of laser photocoagulation to promote disappearance of drusen in patients with age-related macular degeneration (AMD) are currently being evaluated in randomized clinical trials. We sought to undertake a clinicopathological correlation of the effects of laser photocoagulation on drusen in the aged primate retina. Methods. The presence of numerous soft drusen in the fundi of a 29 year old male rhesus monkey was documented by clinical photographs and fluorescein angiography. Argon green laser photocoagulation was performed in a grid pattern to the inferior macula of the left eye. Over the next week, the monkey received daily intravenous injections of bromodeoxyuridine (BrdU) at a dose of 50 mg/kg to label dividing cells. Five weeks later, after repeat photography, the animal was euthanized and the eyes embedded for paraffin sectioning. Sections were stained with H&E or processed for BrdU immunohistochemistry using standard methods and examined by light microscopy. Results. Clinically, the two fundi were similar and contained many soft, nonconfluent drusen, all greater than 63 μm in size. There were 23 soft drusen in the left eye and 28 in the right eye. The majority of larger drusen were between 125 urn and 250 urn in size, with several approximately 250 μm in diameter. In the left eye, several drusen had been treated directly with laser and had disappeared. There was no apparent remote clinical effect of laser on soft drusen in the six week period of the study. Histopathologically, the soft drusen consisted of eosinophilic material between Bruch's membrane and the retinal pigment epithelium (RPE), with no evidence of choroidal neovascularization. In contrast to human eyes with AMD, there was no diffuse thickening of Bruch's membrane in the aged primate retina. The results of BrdU immunohistochemistry will be illustrated. Conclusions. Clinically and histopathologically, the aged primate retina constitutes a good model for studying the drusen observed in human AMD and for evaluating the effects of laser on the RPE. It does not appear to hold promise as a useful model for the exudative complications of AMD.
|Original language||English (US)|
|Journal||Investigative Ophthalmology and Visual Science|
|State||Published - Dec 1 1997|
ASJC Scopus subject areas
- Sensory Systems
- Cellular and Molecular Neuroscience