The significance of baring of the circumlinear vessel. A prospective study.

Twenty-seven consecutive patients whose diagnoses were previously unestablished and who demonstrated baring of the circumlinear vessel underwent thorough ophthalmologic examinations. Evidence supporting optic nerve damage was found in 24 of these 27 patients. The majority of patients had either primary or secondary glaucoma, although neurologic, ischemic, and retinal causes of optic atrophy were also found. In the three patients in whom no cause was established, either unusual asymmetry or size of cupping was noted. Baring of the circumlinear vessel should alert the examiner to look for causes of optic nerve damage.