FP60

Temporal Retinal Nerve Fiber Layer Thickness Thresholds for Predicting Visual Acuity Decline in Primary Open Angle Glaucoma

Presenting Author: Sneha Rathod

Co- Authors: Karishma Bhate - Chavan
Prabhat Nangia
Sarang Lambat.
Vinay Nangia

Aim: To quantify temporal RNFL thickness in primary open-angle glaucoma (POAG) and define thresholds predicting central visual loss.

Methods: Hospital-based cross-sectional study of 240 eyes (149 patients). BCVA and peripapillary RNFL measured via Spectralis SD-OCT; analyzed using Pearson correlation, t-tests, ANOVA.

Results: Temporal RNFL averaged  51.3±10 µm; BCVA: 0.75±0.29 (r=0.23, p<0.001). Mean BCVA was 0.82 at ≥50 µm versus 0.67 at <50 µm (p < 0.001) ; stratified: 0.82 (≥50 µm), 0.68 (40–49 µm), 0.58 (<40 µm). Each 10 µm RNFL loss reduced BCVA by 0.066. RNFL ≥50 µm gave 2.25× higher odds of perfect VA (1.0). 47% of eyes fell in the 40–50 µm transition zone.

Conclusion: Temporal RNFL thresholds of 50 µm (warning) and 40 µm (critical) on SD-OCT are actionable markers for earlier therapy escalation to preserve central vision in POAG.