Three-dimensional optic nerve head algorithm for the detection of glaucomatous damage

Abstract.

Purpose: To determine whether a three-dimensional optic disc algorithm could be useful in differentiating optic nerve heads (ONH) with a normal visual field from those with an abnormal visual field also when using a simultaneous stereoscopic computerised ONH analyser. Methods: One eye was randomly chosen from 45 normals and 55 patients with glaucoma (mean deviation –7.7±9.0 dB, corrected pattern standard deviation 3.1±2.3 dB). All the subjects were examined with the Humphrey Perimeter (program 30-2) and with the Topcon Image-net X Rev-3.51b. Using the topographic map of the system, the algorithm of the third moment or cup shape measure was applied to the numbers (the number of points ranged from 623 to 1,883 depending on the size of the disc area) that identify the heights of all the points of the optic disc surface. Findings were analysed by means of the Mann-Whitney U test and receiver operator characteristic curves. Results: The sensitivity and specificity of this three-dimensional ONH algorithm applied to Topcon Image-net was 90.6% and 85.1% respectively. No difference was found between the groups for age, disc area and number of the analysed points. Conclusions: The algorithm of cup shape measure or third moment is a useful parameter to separate eyes with normal from those with abnormal visual field also when using a simultaneous stereoscopic system such as Image-net.