Factors Associated With Retinal Nerve Fiber Layer Asymmetry in Primary Open Angle Glaucoma Among Individuals of...

This study investigated RNFL asymmetry in 834 African ancestry patients with primary open angle glaucoma. Associated with optic disc and visual field differences, RNFL asymmetry may signal early glaucomatous damage.

Primary open angle glaucoma (POAG) disproportionately affects individuals of African ancestry, with retinal nerve fiber layer (RNFL) asymmetry being a potential early marker of glaucomatous damage. This study aimed to determine the prevalence of RNFL asymmetry and to identify associated demographic, clinical, and ocular factors in individuals of African ancestry with POAG.

This cross-sectional study included 834 POAG cases from the Primary Open-Angle African American Glaucoma Genetics study who had bilateral RNFL thickness measurements. RNFL asymmetry was defined as an interocular RNFL thickness difference of >9 µm. Demographic, clinical, and ocular characteristics were compared between individuals with and without RNFL asymmetry using univariable and multivariable logistic regression.

Among 834 POAG cases, 32.09% (95% CI: 28.93-35.38%) had RNFL asymmetry. In univariate analysis, compared with patients without RNFL asymmetry, patients with asymmetry exhibited significantly larger differences in the following: average and vertical cup-to-disc ratio (CDR), visual field (VF) mean deviation (MD), and pattern standard deviation (PSD), rim area, and cup volume ( P <0.001). In their worse eye, patients with RNFL asymmetry had a smaller rim area ( P <0.001) and a larger average and vertical CDR ( P =0.002, P <0.001, respectively). In multivariate analysis, greater rim area difference (OR: 1.92, P <0.001) and a more negative PSD difference (OR: 0.69, P <0.001) were significantly associated with risk of RNFL asymmetry.

In POAG patients of African ancestry, RNFL asymmetry is linked to optic disc structural asymmetries and-in a subset with available visual field data-functional asymmetries. These findings suggest RNFL asymmetry may indicate asymmetric glaucomatous damage, though prospective validation with comprehensive functional testing is needed to establish clinical utility.