Abstract
Purpose: :
To determine whether low intensity laser treatment applied according to the Complications of Age Related Macular Degeneration Prevention Trial (CAPT) protocols have an effect on drusen resolution and morphology alterations. Clinical and histopatological studies have revealed that drusen, amorphous sub–retinal pigment epithelial cell (RPE) deposits, are common to all forms of age–related macular degeneration (AMD). Soft and confluent drusen are a risk factor for development of vision loss from AMD. Previous studies have suggested that laser photocoagulation therapy is associated with the resolution of drusen in some AMD patients. Furthermore two clinical trials (CNVPT) and (PTAMD) have shown that low intensity laser treatment in eyes with drusen is associated with a reduction in area of drusen. The purpose of this study is to understand morphological changes in the retinas of AMD patients treated in the CAPT trial.
Methods: :
Donor eyes enucleated post mortem from a patient participating in the CAPT trial were obtained from the FFB eye donor program (courtesy of J. Hollyfield). Eyes were fixed in 4% paraformaldehye/0.5% glutaraldehyde. Tissue was cryoprotected in 30% sucrose and embedded in OCT. Cryosections were cut at 10 µm and analyzed by TUNEL and immunohistochemistry.
Results: :
Histological analysis reveals in the treated eye focal areas of RPE hypertrophy, hyperplasia and RPE atrophy. There are a few, thin drusen, some of which contain cells with autofluorescence characteristic of RPE lipofuscin. Cells with immunoreactivity to the macrophage marker CD68 were present in the INL only in the treated eye. Neovascularization was absent from both eyes. The untreated eye had a large area of geographic atrophy in which RPE cells and photoreceptors were absent and Muller glial cells processes extend to Bruch’s membrane.
Conclusions: :
A number of studies have suggested that laser photocoagulation treatment can reduce the area of drusen in patients with AMD. Although the exact mechanism by which laser treatment causes drusen resolution is not known it is possible that macrophage and/or RPE activation may play a role in this phenomenon.
Keywords: age-related macular degeneration • immunohistochemistry