Aim: To determine the sensitivity and specificity of the stereometric optic nerve head (ONH) parameters of the Heidelberg Retina Tomograph (HRT) to detect an event of progression verified in serial stereoscopic ONH photography.
Methods: A retrospective study of 476 eyes of 342 patients with more than 18 months of follow-up with successful stereoscopic ONH photography was conducted. All eyes had good quality HRT examinations with perfect image alignment. 51 (11 %) eyes showed progression in the stereoscopic ONH photographs between visits. The photographs were evaluated by experienced masked observers, whose inter-observer agreement (kappa) varied between 0.403 and 0.510.
Results: The change in most (13/22) of the stereometric ONH parameters showed a statistically significant correlation with progression. The parameter with the best correlation for progression (p < 0.0005) was the cup : disc area ratio. The parameter with the largest area under the ROC curve (0.726) was the vertical cup : disc ratio. The linear discriminant function with the best correlation with progression was [(12.241 × cup : disc area ratio) + (3.540 × mean cup depth) - (2.146 × horizontal cup : disc ratio) + (27.486 × average variability)]. An optimized change in the linear discriminant function value was 0.34 with a 65 % sensitivity and a 69 % specificity for progression.
Conclusions: Despite good image quality, the change in the stereometric ONH parameters did not have high sensitivity and specificity for progression detected with photographs. This indicates that the evaluation of glaucomatous progression in the ONH should not rely solely on the stereometric parameters of the HRT.