Sensitivity and Specificity of Qualitative Signs to Detect Glaucomatous Optic Nerve Damage

ABSTRACT

Quantitiative evaluation of optic disc parameters such as neural rim area requires relatively sophisticated instruments and time consuming methods which are not generally available for the average ophthalmologist. This study was performed to determine which qualitative sign of optic disc distinguishes best between eyes with and without early glaucomatous visual field defects. Using color polaroid photographs we examined qualitative signs in 207 optic discs of 207 patients with primary open-angle glaucoma and in 158 optic discs of 158 normal subjects matched for age and refractive error. In the group with mild (mean deviation(MD) ; better than -5dB, group 1) to moderate (MD; -6~-10dB, group 2) glaucomatous visual field defects, the best results of specificity and sensitivity were achieved using alterations in the configuration of neural rim width (group 1; Specificity =70.3%, Sensitivity =93.4%), while abnormally large parapapillary chorioretinal atrophy, thinnest neural rim width outside the temporal horizontal sector, and presence of zone beta were signs with relatively high specificity and high sensitivity. In the group with advanced (MD; worse than -11 dB, group 3) visual field defects, thinnest neural rim width outside the temporal horizontal sector was the best sign to distinguish between normal and glaucoma eyes. Signs with high specificity and low sensitivity were optic disc hemorrhage, bayonetting of vessel and baring of circumlinear vessel. These results suggest that alterations in the configuration of neural rim width and parapapillary signs were valuable for early diagnosis of glaucomatous optic nerve damage without sophisticated instruments.