Association between Topographic Features of the Retinal Nerve Fiber Bundle and Good Visual Acuity in Patients with Glaucoma

ABSTRACT

Purpose: Maintaining visual acuity in glaucoma patients is an important part of preventing the deterioration of quality of vision. We identified specific areas of the papillomacular bundle (PMB) that were strongly associated with visual acuity, based on en-face images derived from optical coherence topography (OCT) wide scans.

Methods: The study recruited 23 eyes of 21 glaucoma patients (age: 61.3 ± 13.0 years, M: F = 9:12, Humphrey field analyzer-measured mean deviation: -19.9 ± 6.5 dB) with good best-corrected visual acuity (20/20 or more) and a remaining PMB with a maximum width no more than half that of the vertical disc diameter. En-face images were derived from 12 × 9 mm wide-scan images made with DRI-OCT (Triton, Topcon). Averaged en-face images were created by identifying the disc center and fovea line (DFL) and aligning it between images. We then measured the frequency of remaining PMB at 10 µm intervals along a vertical line intersecting the DFL at its midpoint. Finally, we used a logistic analysis in a much larger group of patients to identify cases of glaucoma with low BCVA (<20/20).

Results: In the averaged en-face image, the residual PMB area appeared as a high-intensity region above the DFL. Analysis showed that residual PMB was most common in an area 830–870 µm above the DFL. The correlation coefficient of residual PMB in this area to BCVA was -0.57 (p < .01), and among OCT parameters in this residual PMB area, the AUC to identify decreased BCVA was highest for ganglion cell complex thickness (0.85, p < .01), with a cutoff of 87.5 µm.

Conclusions: This study identified specific areas of the PMB that were associated with BCVA in wide-scan, en-face OCT images from glaucoma patients. This suggests that it may be possible to identify visual impairment during glaucoma treatment by measuring this area.

KEYWORDS:

• Optical coherence tomography
• visual acuity
• papillomacular bundle
• retinal nerve fiber layer
• glaucoma

Acknowledgments

The authors thank Mr. Tim Hilts for editing this manuscript. Co-authors TK and AM are employed by Topcon Corporation, a commercial company. This retrospective study was approved by the institutional review board of the Tohoku University Graduate School of Medicine (study 2017-1-290)

Additional information

Funding

The study was supported in part by a JST grant from JSPS Kakenhi Grants-in-Aid for Scientific Research (B) (T.N. 20H03838), 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.