Predictive value of individual and regional retinal layer thickness on visual acuity and functional outcomes in the therapy of retinal vein occlusion

Abstract

Purpose: The ability to predict functional outcomes and treatment response would be a breakthrough in the therapy of macular disease. Retinal thickness (RT) has been proposed already as a surrogate marker. The aim of this study was to compare individual retinal layer (RL) thickness with the best corrected visual acuity (BCVA) in patients with Branch Retinal Vein Occlusion (BRVO) and Central Retinal Vein Occlusion (CRVO) treated with ranibizumab.

Methods: 18 patients with CRVO (n=9) and BRVO (n=9) enrolled in phase III randomized multicenter trials with data available at the Vienna Reading Center were included. Spectral-domain optical coherence tomography (SD-OCT) volume scans at baseline and monthly up to month 3 were analyzed. Masked readers manually segmented each RL surface in 14,400 B-scans. Layer thickness (LT) was measured for 8 RL including retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), IS/OS junction, outer segment PR/RPE complex (OPR) and retinal pigment epithelium (RPE). Individual and combined LT were correlated with BCVA at baseline and change in BCVA.

Results: BCVA at baseline was significantly correlated with the total RT in the central mm (CMM) area (R²=0.46, p=0.004) and the thickness of the inner RL in the CMM area (IPL+INL+OPL+ONL, R²=0.50, p=0.002) as well as the total RT in the 1-3mm area (R²=0.26, p=0.043) and the thickness of the inner RL in this area (R²=0.35, p=0.016).<br /> BCVA change at month 3 was significantly correlated with change in total RT in the CMM area (R²=0.37, p=0.022) and the thickness change of the inner RL in the CMM area (IPL+INL+OPL+ONL, R²=0.36, p=0.023) as well as the change in total RT in the 1-3mm area (R²=0.47, p=0.007), the change in thickness of the inner RL in this area (R²=0.43, p=0.011) and the change in thickness of the outer RL (IS/OS junction - RPE) (R²=0.51, p=0.004). No significant correlations were detected for other layers or areas outside 3mm eccentricity from the fovea. The association between any LT and BCVA was lost beyond the baseline examination.

Conclusions: The assessment of individual layers may provide additional prognostic value for functional outcomes under therapy for patients with RVO, especially when focusing on changes in RT in the fovea and in the inner RL.