To objectively define the degree of cupping, the authors extracted 3-dimensional slope surface maps from Cirrus HDTM-OCT data and assessed their differentiating characteristics between normal subjects and glaucomatous patients.

One eye from each of 40 normal subjects and 1 eye from each of 39 patients with glaucoma were examined using automated visual field perimetry and Cirrus HDTM-OCT. The Optic Disc Cube 200 × 200 protocol was performed. The individual OCT data were reconstructed as the 3-dimensional surface maps of the optic disc cup and the slope of each contour was calculated using custom-developed software. Several disc cup slope parameters were derived. The parameters measuring the internal features of the optic disc cup were calculated and compared between groups.

Sum of cup slope, sum of thresholded cup slope, and sum of thresholded cup slope / thresholded cup area parameters were differentiating factors between the normal and glaucoma groups ( p < 0.05). The area under the receiver operating characteristic curve (AUROC) value of the slope parameters ranged from 0.718 to 0.753. The sum of thresholded cup slope / thresholded cup area parameter was well correlated with visual field mean deviation (r = -0.250, p = 0.028).

The optic disc cup slope parameter obtained with OCT may be a useful parameter for representing glaucomatous cupping.