Influence of myopic disc shape on the diagnostic precision of the Heidelberg Retina Tomograph.

PURPOSE: To investigate the diagnostic capability of a glaucoma diagnostic classification program for the Heidelberg Retina Tomograph (HRT) in eyes with myopic disc shapes.

METHODS: Sixty-six normal subjects (66 eyes) and 78 open-angle glaucoma patients (78 eyes) were enrolled. The eyes were divided into two groups; those eyes with myopic and those with nonmyopic disc shapes. The classification was based on clinical judgment made after the examination of stereophotographs of the discs without considering the refractive errors. The agreement between the classification program and the clinical diagnosis was evaluated for sensitivity, specificity, and diagnostic precision. The influence of the disc shape on the HRT topographic parameters was evaluated.

RESULTS: The sensitivity, specificity, and diagnostic precision of the HRT were 83%, 95%, and 89% in eyes with nonmyopic disc shapes, but 71%, 96%, and 83% in those with myopic disc shapes. Rim volume, height variation contour, mean retinal fiber nerve layer (RNFL) thickness, and RNFL cross-section area were significantly larger in eyes with myopic disc shapes than in eyes with nonmyopic discs, regardless of the clinical diagnosis.

CONCLUSIONS: The classification program should be modified to take into account the myopic disc shape in order to improve its capability to make more accurate diagnosis of glaucoma possible.