Logistic regression analysis for early glaucoma diagnosis using optical coherence tomography.

OBJECTIVE: To determine and validate the diagnostic ability of a linear discriminant function (LDF) based on the retinal nerve fiber layer thickness at each of the 12 clock-hour positions obtained using optical coherence tomography for discriminating between healthy eyes and eyes with early glaucomatous visual field loss.
METHODS: We prospectively selected 62 consecutive healthy individuals and 73 patients with open-angle glaucoma to calculate the LDF. Another independent prospective sample of 280 healthy eyes and 302 glaucomatous eyes was used to evaluate the diagnostic accuracy of the LDF.
RESULTS: The proposed function was LDF = 15.584 - (12-o'clock segment thickness x 0.032) - (7-o'clock segment thickness x 0.041) - (3-o'clock segment thickness [nasal side] x 0.121). The greatest area under the receiver operating characteristic curve was observed for our LDF in both populations: 0.962 and 0.922. Our LDF and the average thickness yielded sensitivities of 74.5% and 67.8%, respectively, at a fixed specificity of 95%.
CONCLUSIONS: The LDF increased the diagnostic ability of the isolated retinal nerve fiber layer thickness at the 12 clock-hour positions. Compared with optical coherence tomography-provided parameters, our LDF had the highest sensitivities at 85% and 95% fixed specificities to discriminate between healthy and early glaucomatous eyes.