Baring of a circumlinear vessel in glaucoma.

We independently examined 144 optic disc stereophotographs. Despite a preliminary learning trial, we were able to agree about the presence of a circumlinear vessel in only 73% of eyes and about baring of a vessel, if present, in only 71% of eyes. Bared vessels were present in 73% of 22 glaucomatous eyes, 41% of 71 ocular hypertensive eyes, and 14% of 51 normal eyes. During several years of follow-up of 44 ocular hypertensive eyes with bared circumlinear vessels, visual field defects developed in only three. We conclude that baring of a circumlinear vessel is a difficult sign for trained observers to detect with certainty and, although present frequently in glaucoma, is of low specificity as a sign or predictor of glaucomatous damage.