Detecting an Event of Progression Using Glaucoma Probability Score and the Stereometric Parameters of Heidelberg Retina Tomograph 3

Abstract

To evaluate the correlation of the change in glaucoma probability score (GPS) and the stereometric optic nerve head (ONH) parameters of the Heidelberg Retina Tomograph (HRT)3 to an event of glaucomatous progression observed with stereoscopic ONH photography. The subjects for this retrospective follow-up study were monitored with the HRT and stereoscopic ONH photographs. Stable, high-quality imaging and at least 18 months of follow-up was required. The topography examinations were acquired using HRT II and calculated with HRT3 software. The event of progression was determined by masked evaluation of stereoscopic ONH photographs. A total of 476 eyes of 342 subjects met the inclusion criteria. All the examinations with HRT II were backwards compatible with either the GPS or the stereometric parameters of HRT3. The highest statistical significance for the correlation with progression was observed in the change in cup volume and cup:disc area ratio (p<0.0005). The vertical cup:disc ratio was the parameter with the largest area under the receiver operating characteristics curve (AUC = 0.696). The AUC calculated for the change in GPS was 0.541. The GPS showed no statistically significant correlation with progression (p = 0.213). Detecting an event of glaucomatous progression should not be based solely on the change in GPS or the stereometric parameters of the HRT. The good backwards compatibility between HRT II and HRT3 should allow the detection of a trend of glaucomatous progression even when changing from HRT II to HRT3 during the follow-up of glaucoma.