Diagnostic ability of a linear discriminant function for optic nerve head parameters measured with optical coherence tomography for perimetric glaucoma

BACKGROUND/AIMS: To calculate and validate a linear discriminant function (LDF) for optical coherence tomography (OCT) to improve the diagnostic ability of isolated optic nerve head (ONH) parameters to discriminate between healthy individuals and glaucoma patients. METHODS: Two independent samples (teaching and validating sets) were prospectively selected. The teaching set (54 normal eyes and 73 glaucoma patients) was used to calculate the LDF. The validating set (70 healthy individuals and 67 glaucoma patients) was used to test the performance of the LDF in an independent population. Receiver operating characteristic (ROC) curves were plotted and compared with the ONH parameters measured using OCT. RESULTS: The optimized function was: LDF=8.204+(2.59xdisc area)-(9.25xhorizontal rim width). The largest areas under the ROC curve were 0.923 and 0.898 for our LDF and the vertical rim area in the validating population respectively. There were no significant differences between the areas. At 95% fixed specificity, the LDF (71.64%) and the vertical rim area (65.67%) yielded the highest sensitivity values. CONCLUSIONS: All ONH parameters obtained with OCT, except disc area, had a good ability to differentiate between healthy and glaucoma individuals. As judged by the area under the ROC curve, the LDF performed better than any single parameter, although statistics did not prove it better than vertical cup/disc ratio or vertical rim area with the number of subjects we studied.