Flat preparations of the retinal vessels in Coats' disease.

Flat preparations of the retina were prepared by trypsin digestion in ten cases of Coats' disease. All of the patients were young males with advanced disease leading to enucleation. All eyes showed marked abnormalities in the arterioles, venules, and capillaries. The findings most characteristic of Coats' disease were large aneurysms and thick PAS positive deposits in vessel walls. The aneurysms ranged from 50 to 350 microns and frequently formed large sausage-like or beaded out-pouchings and were sometimes situated on shunt vessels. Other findings frequently seen, but not specific for Coats' disease, were capillary dilatation, small aneurysms, hypocellular vessel walls, and fibrous strands.