Optic disc surface smoothness and visual field indices

Abstract ·

Background: In order to ascertain whether the optic disc surface smoothness (ODSS) could be used to predict the amount of visual field damage in glaucomatous eyes, the correlations between ODSS and visual field indices were evaluated. · Methods: One eye was randomly chosen from each of 40 normals and 50 patients with glaucoma. The morphology of the optic disc surface was analyzed using the Topcon IMAGEnet X Rev-3.51b. In order to define the level of “smoothness” of the optic disc surface, the differences of the relative position of each surface point was studied by measuring the standard deviation (SD) from the average height of the points (number of points ranged from 623 to 1883 depending on the size of the disc area) that identify the optic disc surface. All the subjects were also examined with the Humphrey perimeter (Program 30-2) and the results were analyzed by Mann-Whitney U-test and Spearman rank correlation coefficient. · Results: The difference in ODSS between the glaucomatous and the normal eyes was statistically significant. No significant correlation was found between age and ODSS. A significant correlation was found between ODSS and mean deviation (MD) and between ODSS and corrected pattern standard deviation (CPSD). In the glaucoma group there were significant correlations between ODSS and the perimetric indices MD and CPSD; no correlations were found in the normal group. · Conclusion: The ability of ODSS to reflect the level of visual field change in glaucomatous eyes appears to be rather limited, even if statistically significant. This fact does not limit the clinical usefulness of ODSS as a diagnostic parameter in consequence of its strong correlations with the other morphometric parameters and its high sensitivity and specificity in separating normal from glaucomatous eyes.