OCT patterns of macular edema and response to bevacizumab therapy in retinal vein occlusion.

BACKGROUND: Baseline OCT morphology of macular edema (ME) due to branch (BRVO) or central retinal vein occlusion (CRVO) was evaluated with respect to response to bevacizumab treatment.

METHODS: Sixty-five patients (33 CRVO, 32 BRVO) were treated with intravitreal injections of 2.5 mg bevacizumab. Reinjections were only performed if ME persisted or recurred. Follow-up ranged from 23 to 128 weeks. OCT (Stratus OCT™, Carl Zeiss Meditec) morphology at baseline was analyzed retrospectively to evaluate its effect on treatment outcome (ETDRS visual acuity and central retinal thickness). Baseline OCT scans were studied with regard to central retinal thickness (CRT), presence and height of subretinal fluid (SRF), intraretinal cystoid spaces (ICS) and maximum horizontal diameter of the largest delimitable ICS.

RESULTS: In CRVO patients, baseline CRT is not correlated with CRT at last visit, but there is a significant correlation of baseline CRT with final visual acuity (VA). Presence of SRF and diameter of ICS do not influence functional and morphological response to bevacizumab treatment. Baseline CRT in BRVO patients is not significantly correlated with final VA and final CRT. There is no difference in treatment response between patients with or without baseline SRF. BRVO patients with large ICS >600 μm (13.8%) at baseline had a significantly worse VA at last visit than patients with smaller ICS (p = 0.011), and did not achieve a significant improvement under bevacizumab therapy. The duration of retinal vein occlusion before start of treatment was significantly longer in patients with ICS >600 μm (232 ± 96 weeks versus 17 ± 17 weeks; p < 0.001). There is no correlation of ICS diameter and duration of vein occlusion in patients with ICS <600 µm.

CONCLUSIONS: In CRVO patients, baseline CRT and final VA are significantly correlated, whereas the presence of SRF or diameter of ICS was not predictive for treatment outcome. In BRVO patients, ICS with a diameter of >600 μm are associated with a long duration of vein occlusion and poor functional response to treatment with bevacizumab. CRT and SRF were not found to be significant prognostic factors.