Spectral-domain optical coherence tomography (SD-OCT) patterns and response to intravitreal bevacizumab therapy in macular edema associated with branch retinal vein occlusion

To evaluate the baseline spectral-domain optical coherence tomography (SD-OCT) characteristics of macular edema (ME) due to branch retinal vein occlusion (BRVO) for visual outcome after intravitreal bevacizumab injection.

Fifty-nine patients treated in one eye with intravitreal bevacizumab for ME due to BRVO were retrospectively reviewed. Stepwise multiple regression analysis was used to evaluate the relative contribution of several variables, including SD-OCT characteristics such as photoreceptor inner segment/outer segment (IS/OS) integrity and external limiting membrane (ELM status), baseline best-corrected visual acuity (BCVA), and baseline central retinal thickness (CRT) with final visual outcome.

Thirty-one patients (52.5 %) had disrupted photoreceptor IS/OS integrity. The mean BCVA improved significantly from 0.50 logMAR (20/63 Snellen equivalent) to 0.10 logMAR (20/25 Snellen equivalent) in the intact photoreceptor group (p = 0.000, paired t-test). However, the mean BCVA was improved in the disrupted photoreceptor group, from 1.10 logMAR (20/252 Snellen equivalent) to 0.94 logMAR (20/174 Snellen equivalent), which was not statistically significant (p = 0.177, paired t-test). ELM was disrupted in 23 patients (39.0 %). The mean BCVA improved significantly from 0.63 logMAR (20/85 Snellen equivalent) to 0.26 logMAR (20/36 Snellen equivalent) in the intact ELM group (p =  0.000, paired t-test), however, not significantly improved in the disrupted ELM group, from 1.09 logMAR (20/246 Snellen equivalent) to 1.01 logMAR (20/205 Snellen equivalent) (p =  0.563, paired t-test). The strongest individual predictor of final BCVA among patients with ME due to BRVO was the integrity of photoreceptor IS/OS layer on SD OCT (r ² = 0.514, p = 0.000, stepwise multiple regression), but the most efficient model was the combination of the photoreceptor IS/OS integrity, ELM status, and baseline BCVA (r ² = 0.671, p = 0.000, stepwise multiple regression). The strongest predictor of final BCVA was the status of photoreceptor IS/OS integrity (β = 0.532, p = 0.000, stepwise multiple regression), followed by ELM status (β = 0.325, p = 0.006, stepwise multiple regression), and the baseline BCVA (β = 0.238, p = 0.013, stepwise multiple regression).

Our results suggest that baseline SD-OCT characteristics, the status of photoreceptor IS/OS and ELM can be helpful in predicting the final visual outcome after intravitreal bevacizumab injection in these patients.