Baring of the circumlinear vessel. An early sign of optic nerve damage.

Baring of the circumlinear vessel is reported as an early sign of optic nerve damage. Evidence is presented to show that this finding is not present in the normal population and, unlike previously described signs of glaucomatous cupping, can be observed at a stage of glaucoma prior to the development of visual field loss. Analysis of a series of stereoscopic photographs from selected high-risk ocular hypertensive patients disclosed a 54% incidence of baring of the circumlinear vessel. Although initially thought to be pathognomonic for glaucomatous cupping, baring of the circumlinear vessel is seen rarely in acquired cupping from optic atrophy secondary to other causes.