Sensitivity and specificity of optic disc parameters in chronic glaucoma

Optic disc parameters are commonly used for the early detection of glaucomatous optic discs. We used receiver operating characteristics (ROC) curves to illustrate the separation characteristics of different disc parameters for this purpose. We performed computer perimetry and computerized optic disc topometry on 93 eyes of 53 subjects with glaucoma and glaucoma-related diseases. The optic disc parameters were correlated with visual field indexes, and ROC curves for the detection of glaucomatous disc changes were calculated. According to clinical experience, the vertical cup/disc ratio was able to identify the glaucomatous eyes the most easily, whereas the neuroretinal rim area was less helpful in this regard. In terms of the correlation of optic disc parameters with visual field indexes, the rim area was the more powerful of the two. The cup volume showed neither separation of glaucomatous from normal eyes nor correlation with visual field indexes. The vertical cup-to-disc ratio is the most suitable for screening purposes, whereas the rim area is more valuable for follow-up evaluation.