Evaluation of Papillomacular Nerve Fiber Bundle Thickness in Glaucoma Patients with Visual Acuity Disturbance

ABSTRACT

Purpose

Assessing the papillomacular nerve fiber bundle (PMB) can identify glaucoma patients with decreased visual acuity. In this study, we explore efficient methods for evaluating PMB thickness in glaucoma patients, based on swept source-optical coherence tomography (SS-OCT).

Methods

This study included 347 eyes of 205 open-angle glaucoma (OAG) patients. Patients were excluded if they had best-corrected decimal visual acuity < 0.3, axial length >28 mm, non-glaucoma ocular disease, or systemic disease affecting the visual field. We obtained vertical 12.0 × 9.0 mm 3D volume scans covering both the macular and optic disc regions with SS-OCT (DRI OCT Triton, Topcon), and measured the thickness of the PMB, as well as average macular retinal nerve fiber layer thickness (mRNFLT) and macular ganglion cell complex thickness (mGCCT) in the macular map and temporal-quadrant circumpapillary RNFL thickness (tcpRNFLT). We also measured central-strip RNFLT (csRNFLT) and GCC (csGCCT) in a 1.5 × 6.6 mm area of the scan centered between the fovea and optic nerve head. CsRNFLT and csGCCT were divided lengthwise into three 1.5 × 2.2 mm sections. We then calculated Spearman’s rank correlation coefficient between these OCT measurements and visual acuity. Logistic regression analysis was used to find the cutoff value for the OCT measurements to predict logMAR < 0.

Results

The correlation coefficients with logMAR were 0.38 for mRNFLT, 0.44 for mGCCT, 0.37 for middle csRNFLT, 0.50 for middle csGCCT, and 0.33 for tcpRNFLT (all P < .0001). For middle csGCCT, the area under the curve indicating decreased visual acuity was 0.80, with a cutoff value of 88.6 μm (P < .001).

Conclusions

We found strong associations between OCT parameters in the PMB, especially middle csGCCT, and visual acuity in patients with OAG. The thickness of the PMB may therefore be valuable information for glaucoma care and may help prevent visual acuity disturbance.

KEYWORDS:

• Ganglion cell complex
• papillomacular bundle
• swept-source optical coherence tomography
• normal-tension glaucoma
• reproducibility

Acknowledgments

The authors thank Mr. Tim Hilts for editing this manuscript and Mrs. Minami Yoshida for technical assistance.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

Tsutomu Kikawa and Masahiro Akiba are employed by Topcon Corporation, a commercial entity. This retrospective study was approved by the institutional review board of Tohoku University Graduate School of Medicine (study 2017-1-290). This paper was supported in part by a JST grant from JSPS KAKENHI Grants-in-Aid for Scientific Research (B) [T.N. 26293372], by the JST Center for Revitalization Promotion and KAKENHI Grants-in-Aid for young scientists (B) [K.O. 17K16957] and by the Public Trust Suda Memorial Fund for Glaucoma Research.