Topographic correlation between optic nerve head characteristics and retinal nerve fibre layer defect in primary open-angle glaucoma patients: Korea National Health and Nutrition Examination Survey

Purpose To evaluate topographic correlations of the directions of β-zone peripapillary atrophy (PPA) and optic disc torsion with retinal nerve fibre layer (RNFL) defect in a Korean population. Methods Among 292 primary open-angle glaucoma (POAG) patients from the 2012 KNHANES (n = 7444, age ≥ 19 years), 93 eyes of 93 individuals with a single localized RNFL defect were enrolled. The angular locations of the point of maximum radial extent (PMRE) of β-zone PPA and the optic disc torsion were measured on fundus photography. The angular location of the PMRE and the torsion degree (TD) were noted when the absolute value of the former or the latter was ≥15 degrees from the reference line, a line drawn from the centre of the optic disc to the fovea. Results The overall POAG prevalence was estimated as 4.2% (95% confidence interval [CI], 3.6-4.9). Of the POAG eyes with a single localized RNFL defect, 39.5% had superior or inferior PMRE of β-zone PPA; in 74.9% (p = 0.015) of those cases, the RNFL defect was located in the same hemifield as the angular location of the PMRE. Meanwhile, 40.4% of the POAG eyes with a single localized RNFL defect showed accompanying optic disc torsion. The correlation rate between the direction of the optic disc torsion and the RNFL defect location was 60.2% (p = 0.029). Conclusions In the Korean POAG patients examined, the directions of the PMRE of β-zone PPA and of the optic disc torsion showed significant associations with the RNFL defect location.