Correlation of Disc Morphology Quantified on Stereophotographs to Results by Heidelberg Retina Tomograph II, GDx Variable Corneal Compensation, and Visual Field Tests

Abstract

Quantification of disc morphology by computer-assisted planimetry on stereophotographs and to compare the results with those by other fundus structure imaging devices and visual field tests. Cross-sectional study. Fifteen normal eyes of 15 normal subjects and 69 glaucomatous eyes of 69 open-angle glaucoma patients. Sequential digital stereophotographs of the optic discs were obtained by a nonmydriatic fundus camera. Intraobserver reproducibility for the 3 repeated traces and interobserver reproducibility for the three individual examiners were determined. The obtained results were correlated to those by Heidelberg Retina Tomograph (HRT) II, GDx with variable corneal compensation (VCC) and visual field tests obtained within 2 months of the photography. Optic disc parameters such as disc area, cup area, rim/disc area ratio, vertical cup diameter/disc diameter (Cd/Dd) ratio and rim width/disc diameter (Rw/Dd) ratio at radial arbitrary angles. Interclass correlation coefficients (ICC) and coefficients of variance (CV) for the optic disc parameters and their correlation with HRT II, GDx VCC, and visual field test results. Intra- and interobserver ICC and CV were 0.88 to 0.99, 1.1% to 9.6%, and 0.72 to 0.98, 2.2% to 11.9% for area parameters, 0.81 to 0.92, 2.4% to 4.0% and 0.71 to 0.78, 4.3% to 5.0% for Cd/Dd ratio, and 0.73 to 0.91, 9.2% to 23.0% and 0.65 to 0.82, 16.9% to 27.2% for Rw/Dd ratios, respectively. Significant correlation was seen between disc and cup area and the corresponding parameters by HRT II (r(s) > 0.81; P<0.001), as well as between vertical Cd/Dd ratio and global TSNIT average by GDx VCC and visual field test indices (|r(s)| > 0.51; P<0.001), and between superior and inferior Rw/Dd ratio and their corresponding sectoral HRT II, GDx VCC and visual field test indices (r(s) > 0.31; P<0.006), respectively. Correlation with visual field test indices was comparable among stereophotographs, HRT II, and GDx VCC parameters. Optic disc morphologic parameters quantified on stereophotographs by our software showed satisfactory reproducibility and good correlation with those measured by other fundus structure imaging devices and visual field test results, indicating its clinical usefulness, especially in the mass screening of glaucoma.