Stereoscopic Analysis of Optic Nerve Head Parameters in Primary Open Angle Glaucoma: The Glaucoma Stereo Analysis Study

Abstract

PurposeThe Glaucoma Stereo Analysis Study (GSAS), a cross sectional multicenter collaborative study, used a stereo fundus camera to assess various morphological parameters of the optic nerve head (ONH) in glaucoma patients and investigated the relationships between these parameters and patient characteristics.Subjects and MethodsThe study included 187 eyes of 187 subjects with primary open angle glaucoma or normal tension glaucoma (male: female = 100: 87, age = 61±9 years). Stereo pairs of ONH photographs were made with a stereo fundus camera (nonmyd WX). ONH morphological parameters were calculated with prototype analysis software. In addition to 35 standard parameters, we defined three novel parameters: disc tilt angle, rim decentering, and the absolute value of rim decentering. The correlation between each parameter and patient characteristics was analyzed with Spearman's rank correlation coefficient.ResultsPatient characteristics included refractive error of −3.38±3.75 diopters, intraocular pressure (IOP) of 13.6±2.6 mmHg, and visual field mean deviation (MD) of −4.71±3.26 dB. Representative ONH parameters included a horizontal disc width of 1.66±0.28 mm, vertical disc width of 1.86±0.23 mm, disc area of 2.42±0.63 mm2, cup area of 1.45±0.57 mm2, and cup volume of 0.31±0.22 mm3. Correlation analysis revealed significant negative associations between vertical cup-to-disc ratio (0.82±0.08) and MD (r = −0.40, P<0.01) and between disc tilt angle (10.5±12.5 degrees) and refractive error (r = −0.36, P<0.01). Seventy-five percent of the eyes had a positive value for rim decentering (0.30±0.42), indicating that rim thinning manifested more often as an inferior lesion than a superior lesion.ConclusionWe used stereoscopic analysis to establish a database of ONH parameters, which may facilitate future studies of glaucomatous changes in ONH morphology.

Validation of formula‐predicted glaucomatous optic disc appearances: the Glaucoma Stereo Analysis Study

“…The inclusion and exclusion criteria, methods of ophthalmic examinations, diagnosis of POAG and rules for data collection were reported previously (Yokoyama et al. ).…”

“…The depth and volume values were calculated based on the disparity between the right and left images of the stereo image pair with a stereo matching technique, with correction for magnification by a modification of Littman's method using the refractive error and corneal curvature of each eye (Yokoyama et al. ). Rim decentring can range from −1, defined as rim thinning in the superotemporal area without rim thinning in the inferotemporal area, and 1, defined as rim thinning at the inferotemporal area without rim thinning at the superotemporal area; 0 indicates equally thinned rims at both the supero‐ and inferotemporal rims.…”

“…The Glaucoma Stereo Analysis Study (GSAS) is a multicentre collaborative study in which this technique is used to assess various optic disc morphologic parameters in Japanese patients with primary open‐angle glaucoma (POAG), as reported in the study's initial dataset (Yokoyama et al. ).…”

Morphological Diagnostics in Paediatric Glaucoma-Analysis of the Disc Damage Likelihood Scale by KOWA Non Mydriatic Fundus Camera and its Correlation to HRT and OCT

“…It was defined by a horizontal line through the centre of the papilla. several points on the contour (usually [8][9][10][11][12], and the contour line was then automatically generated by software spline interpolation [18].…”

“…This relationship of KOWA and HRT in manifest glaucoma, in contrast to the difference in glaucoma suspects, may be used for observing progression in manifest glaucoma. Population-based studies using fundus photography have found that the area of the ONH ranged from 2.09 to 2.94 mm 2 [18,29].…”