Vol 34 No 1 Original Article PDF

Correlation of structure and function in glaucoma

Maria Joanna Rodriguez-Chan, MD, Patricia M. Khu, MD, MS, Ma. Margarita L. Luna, MD, Manuel B. Agulto, MD

This study assessed the relationship of two structural tests, optic-disc photography and optical coherence tomography (OCT), and a functional test, standard achromatic perimetry (SAP), in the diagnosis of glaucoma.

A retrospective review of charts from the database of a private glaucoma specialist and the glaucoma clinic of a tertiary hospital was done. The participants were longitudinally evaluated and had comprehensive eye examination, imaging, and functional testing. Optic-disc photographs, OCTs, and SAPs were interpreted and evaluated separately, and then correlated with each other by two glaucoma experts working individually. Sensitivities, specificities, and predictive values were obtained for each diagnostic test and in combination. Kappa statistics were used for interobserver agreement.

Three hundred sixty-seven eyes of 188 patients were included in the study. Fifty-eight patients were diagnosed as normal, 130 had glaucoma. OCT had the highest sensitivity and specificity at 70.7% and 76.6%, followed by SAP at 72.4% and 53.5% respectively. Optic-disc photos had the lowest sensitivity and specificity at 55.8% and 54.4% respectively, and the lowest interobserver agreement (kappa = 0.50-0.61). The predictive values of the 3 tests increased to 82% with good interobserver agreement (kappa = 0.68-0.78) when correlated with each other.

The correlation of structural and functional tests increased the accuracy of diagnosing glaucoma. These examinations offered complementary information and, when used in conjunction with comprehensive clinical evaluation, guided the clinician in the proper management of patients with glaucoma.

Keywords: Glaucoma, Optic-nerve head, Glaucomatous optic neuropathy, Optic-disc photography, Optical coherence tomography, Standard achromatic perimetry, Visual field