RA DA CUMULATIVE CURVE ANALYSIS OF LOCAL AND DIFFUSE NEURORETINAL RIMAREA DAMAGE IN GLAUCOMA PATIENTS/

Aim-To evaluate the validity of cumulative rim/disc area (RA/DA) curve analysis as a clinical tool for the identification of glaucoma induce d optic disc pathology. Methods-71 normal and 83 glaucomatous eyes wer e evaluated from a series of 154 subjects recruited for this study. Fo r each eye, the cumulative distribution of RA/DA was calculated from 3 6 equally spaced rim sectors of each optic disc obtained by the automa tic evaluation of simultaneous videographics (Image-net X Rev.3/51b). To increase the sensitivity of this analysis in early glaucoma and in normal eyes, these cumulative curves were subsequently divided into tw o equal segments and the slopes of their respective regression lines c ompared. Results-The median RA/DA value obtained from the 36 sectors w as significantly different in glaucomatous eyes compared with normals (p <0.001). Nevertheless, the curves (5th-95th percentile of the cumul ative curves distribution) of early glaucomatous eyes fell within the normal range. When the cumulative curve of these marginal cases was th en divided into two equal segments, the comparison of the slopes of th e regression lines showed a significant difference (p <0.05) in 100% o f early glaucomatous eyes. Furthermore, normal eyes were shown to be t rue negatives in 93% of the cases in which no significant difference b etween the two slopes was observed. Conclusion-Analysis of the RA/DA c umulative curve fi.om 36 sectors of the optic disc was a valid method for the identification of glaucomatous disc pathology; however, a furt her calculation of the slopes of the two RA/DA regression lines was ne eded to identify early glaucomatous damage.