Sensitivity, Specificity, and Predictive Value of Optic Disc Parameters in Primary Open-Angle Glaucoma

ABSTRACT

Attempts to quantify the parameters of optic nerve head structure have been made to recognize the earliest structural abnormalities in glaucoma, and to efficiently monitor the structural changes of the optic nerve head with advancing disease. Optic disc parameters were measured in 88 normal subjects and 149 primary open-angle glaucoma patients using a computer graphic program (Adobe photoshopTM) and the photographic magnification was corrected according to Littmanns method. The sensitivity, specificity, and predictive value of optic disc parameters were calculated to discriminate between normal and glaucomatous eyes at different stages of glaucoma. Receiver operating characteristics curves were used for comparisons of different disc parameters. In the group with mild glaucomatous visual field (VF) defects (mean deviation (MD); better than -5dB, group 1), optic disc parameters did not provide greater sensitivity and specificity enough to detect early glaucomatous optic nerve head damage. In the group with moderate VF defects (MD; -6~-10dB, group 2) and advanced VF defects (MD; worse than -11dB, group 3), the minimum rim width within the 60 sector across the vertical meridian (predictive value; 84.4%, 95.9%, respectively), vertical cup to disc ratio (83.7%, 95.2%, respectively), and rim area to disc area ratio (83.7%, 95.1%, respectively) were helpful to identify the glaucomatous eyes, whereas horizontal cup to disc ratio (77.3%, 90.3%, respectively) and cup area (75.2%, 89.0%, respectively) were less helpful in this regard.