Association of Retinal Sensitivity and Morphology during Antiangiogenic Treatment of Retinal Vein Occlusion over One Year

Abstract

Evaluation of the association between functional and anatomic retinal changes during anti-vascular endothelial growth factor (VEGF) therapy with bevacizumab (Avastin) in patients with cystoid macular edema secondary to retinal vein occlusion (RVO) using microperimetry and spectral domain optical coherence tomography (SD-OCT). Prospective, uncontrolled study (EUDRACT NR-2005-003288-21). Twenty-eight patients with cystoid macular edema secondary to RVO. Patients initially received 3 consecutive intravitreal injections of 1.25 mg bevacizumab at 4-week intervals. Further treatment was based on morphologic (OCT) and functional best-corrected visual acuity (BCVA) findings. During the 1-year follow-up, a rigorous standardized evaluation was performed monthly. Macular function was documented by microperimetry (Nidek, MP1 Microperimeter) and BCVA based on the Early Treatment in Diabetic Retinopathy Study (ETDRS). Morphologic parameters included central retinal thickness (CRT) as measured by conventional OCT (Stratus), and central subfield thickness (CST), mean retinal thickness (MRT), and retinal volume (RV) measured by SD-OCT. Imaging of retinal morphology using OCT and SD-OCT and evaluation of retinal function assessed with microperimetry and ETDRS charts during 12 months of anti-VEGF treatment. Within 6 months, the mean area of absolute scotoma was reduced from 21.4% of the central visual field to 6.4% and remained at this level until month 12 (7.4%). Mean BCVA improved from 51 to 66 letters on ETDRS charts. The CRT, CST, and MRT decreased significantly (P<0.002) and remained stable during the follow-up. The RV values did not improve significantly under therapy. Statistical analysis using a linear effects model revealed significant associations between the functional and morphologic outcomes, most notably between BCVA, macular sensitivity, CRT (Stratus OCT), CST, and MRT (Cirrus OCT) values. Central retinal morphology, especially CRT and CST measured by conventional and SD-OCT, and retinal function improved significantly during treatment of RVO with a flexible dosing regimen of intravitreal bevacizumab. Functional (central visual acuity and visual field) and morphologic parameters (retinal thickness) were significantly related. These associations highlight the value of OCT imaging for assessing this disease entity.