Papillomacular Bundle Thickness is Associated With Visual Acuity in Proliferative Diabetic Retinopathy

Purpose: To determine whether the papillomacular bundle thickness (PBT), measured as the retinal nerve fiber layer (RNFL) thickness at a point halfway between the fovea and the optic disc, is significantly associated with best-corrected visual acuity in eyes with proliferative diabetic retinopathy. Methods: A retrospective observational study was conducted on eyes from patients with a history of proliferative diabetic retinopathy in at least one eye who presented to the Ambulatory Care Network (ACN) Vitreoretinal Clinic at New York-Presbyterian Hospital at Columbia University Irving Medical Center between January and December 2023. The PBT was measured using pre-existing Cirrus OCT 512 x 128 macular cube scans. The ETDRS central subfield thickness (CST) was recorded from the Cirrus review software. Best-corrected visual acuity was obtained from the medical record and converted into an ETDRS letter score. Results: Seventy-seven eyes from 45 patients were included. The mean ETDRS letter score, PBT, and CST were 62.1 ± 16.7 letters, 36.1 ± 13.1 μm, and 284.5 ± 90.7 μm, respectively. PBT was significantly correlated with visual acuity (r = 0.40; p < 0.001), while CST was not (p = 0.43). Linear regression analyzing visual acuity as a function of PBT showed a coefficient of 0.51. Conclusions: Thinning of the PBT is associated with decreased visual acuity in eyes with proliferative diabetic retinopathy. Each 1 micrometer of PBT thinning is expected to result in a loss of approximately 0.5 ETDRS letters.