Topographic Correlation between Optic Nerve Characteristics and Retinal Nerve Fiber Layer Defect in Normal-Tension Glaucoma Patients: the Korea National Health and Nutrition Examination Survey

Abstract

 

Purpose

 

This study evaluated the topographic correlations of the directions of β-zone peripapillary atrophy (PPA) and optic disc torsion with retinal nerve fiber layer (RNFL) defect in the population-based Korea National Health and Nutrition Examination Survey (KNHANES).

 

Methods

 

Among 281 normal-tension glaucoma (NTG) patients from the 2012 KNHANES (n = 7444 subjects, age ≥ 19 years), 92 eyes of 92 individuals with a single RNFL defect were enrolled. The angular locations of the point of maximum radial extent (PMRE) of β-zone PPA and optic disc torsion (both ≥ 15°) were measured on fundus photography. According to the location of the RNFL defect, the eyes were subcategorized into superior and inferior defect groups. All of the statistical estimates were obtained using sample weights adjusted for response rate, extraction rate, and distribution in the Korean population.

 

Results

 

The overall prevalence of glaucoma was estimated to be 4.2% (95% confidence interval [CI], 3.6-4.9), and that of NTG, 3.4% (95% CI, 3.4-4.8). Of the NTG eyes with a single localized RNFL defect, 39.5% had a PMRE of β-zone PPA exceeding 15°; 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. And 40.4% of the NTG eyes with a single localized RNFL defect were accompanied by optic disc torsion. The correlation rate between the RNFL defect location and the direction of the optic disc torsion was 60.2% (P = 0.029).

 

Conclusions

 

In the Korean NTG patients examined, the directions of the PMRE of β-zone PPA and the optic disc torsion showed a significant association with the RNFL defect location. This result has the potential to facilitate localization of RNFL defect in NTG patients.