Large capillary aneurysms secondary to retinal venous obstruction.

Three patients had unusually large capillary aneurysms. Two of the patients had had previous branch vein occlusions, while a third had had a central retinal vein occlusion. The large capillary aneurysms were located in areas of ischaemic retina that were drained by the previously obstructed veins. Retinal ischaemia and, possibly, increased hydrostatic pressure following vein occlusion were postulated to result in the development of these atypical capillary aneurysms. They are similar in size to arterial macroaneurysms, but originate from the venous side of the capillary bed. Like typical capillary microaneurysms and arterial macroaneurysms, these large capillary aneurysms may result in visual loss from macular oedema, serous elevation of the macula, and circinate lipid exudation. Argon laser obliteration of the aneurysms appears to be effective therapy.