Reproducibility of the Heidelberg retina tomograph III glaucoma probability score

PURPOSE: To evaluate the intrasession reproducibility of the Heidelberg Retina Tomograph III (HRT III) Glaucoma Probability Score (GPS) and analyze the factors that may affect it. PATIENTS AND METHODS: Twenty normal subjects and 20 glaucomatous patients underwent 10 HRT III examinations of 1 randomly selected eye during the same session. The reproducibility of the GPS and its parameters was assessed by calculating the intraclass correlation coefficients (ICCs) and 95% confidence intervals of the study population as a whole, and of the 2 subgroups. The factors influencing individual reproducibility were evaluated by means of regression analysis. RESULTS: The reproducibility of the GPS parameters (at a confidence level of 95%) was almost perfect in the population as a whole (ICCs 0.964-0.856) and in the normal subjects (ICCs 0.976-0.897), but decreased in the glaucoma patients in whom it ranged from almost perfect to substantial (ICCs 0.922-0.705). The parameters were mainly influenced by image quality, but also by diagnosis and age, although the probability of glaucoma did not seem to depend on these variables. CONCLUSIONS: GPS is a highly reproducible diagnostic tool, especially in the case of "good" or better quality images as evaluated by the HRT software; moreover, the reproducibility of the GPS parameters was significantly better in normal subjects than in glaucoma patients.