Sensitivity and specificity of optic disc variables and analysis of a new variable (MP/D) for glaucoma diagnosis with the Glaucoma-Scope

AIM: In an attempt to use the quantitative optic disc measurements of the Glaucoma-Scope (OIS Sacramento, CA, USA) to distinguish glaucomatous from normal optic discs, a new variable was investigated, the mean disc corrected for the disc size by dividing by the disc area: MP/D. METHODS: Glaucoma-Scope disc evaluation was performed on 81 eyes of 51 patients split into the following groups based on Humphrey 24-2 visual field and clinical criteria of glaucoma: chronic glaucoma n = 27 (including only early, n = 17, and low tension glaucoma, n = 10), ocular hypertension n = 24, pseudoglaucomatous large discs, n = 12, and normal eyes, n = 18. Classic optic disc variables (the vertical and horizontal c/d ratios, and the c/d area) were compared with the new MP/D index calculating receiver operating characteristic curves. RESULTS: The MP/D ratio was able to identify the glaucomatous eyes more easily than other ratios. Areas under the curves were: 0.91 (MP/D); 0.87 (c/d area); 0.85 (c/d vertical); and 0.80 (c/d horizontal). The MP/D index was also correlated with the mean deviation (r = 0.466; p = 0.001). CONCLUSION: MP/D may prove useful in detecting glaucomatous optic nerve damage and could be an interesting screening tool for primary open angle glaucoma.