Comparison of visual fields and retinal nerve fiber layer thickness in assessing optic nerve head damage in patients with primary open-angle glaucoma

This study aims at evaluating the relationship between visual fields by HFA and retinal nerve fibre layer thickness and ONH parameters by OCT in assessing optic nerve head damage in patients with primary open-angle glaucoma. A total of 87 glaucomatous eyes were included. All subjects underwent complete ophthalmic examination, gonioscopy, visual field examination by Humphrey’s automated visual field analyzer and RNFL thickness and ONH parameters assessment by SD-OCT. Glaucomatous eyes were graded according to Hodapp, Parrish, and Anderson’s classification. Quadrant wise RNFL thickness and average thickness were recorded. Statistical analysis was done using Epidemiological Information Package (EPI) version 7.2. : Average and vertical CD ratio was found to be the most important ONH parameter to discriminate early from moderate glaucoma and for assessing progression from moderate to severe glaucoma. All ONH parameters except the disc area were significant. A significant correlation was detected between mean deviation, pattern standard deviation, and average RNFL thickness. Average RNFL thickness was the best parameter to discriminate early from moderate, and moderate from severe glaucoma. The sectoral RNFL thicknesses also showed a gradual decline and were statistically significant in all sectors in moderate and severe glaucoma and only in inferior and superior sectors in mild and moderate glaucoma. In the present study, average RNFL thickness had a good diagnostic value in the diagnosis of glaucoma and for grading of glaucoma according to its severity. The structural changes on OCT correlated well with functional damage shown on visual fields.