Glaucomatous optic nerve atrophy: the circumlinear vessel revisited.

Baring of a circumlinear vessel, or gap sign, is a sign of glaucomatous optic neuropathy that can be rapidly assessed during direct ophthalmoscopy. We previously found a significant association between the presence of this sign and the diagnosis and status of visual field defects. In the current study we followed this same group of patients for a mean of 78 months. The rate of agreement between two independent observers for the presence or absence of a circumlinear vessel was 79%, and the intraobserver rate was 71%. The corresponding rates for the presence of a gap sign were 84% and 90%. The presence of baring was significantly associated with development of a visual field defect in the glaucoma suspect group (p = 0.0105). The development of a gap sign in photographs taken approximately 6 years later was significantly associated with clinical progression of the appearance of the disc or the visual field defect (p = 0.0142). We conclude that patients with baring of a circumlinear vessel should be closely monitored for the development or progression of the glaucomatous process.