Functional and morphological changes in diabetic macular edema over the course of anti-vascular endothelial growth factor treatment

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To evaluate macular morphology and function in diabetic macular edema (DME) over the course of intravitreal anti-vascular endothelial growth factor (VEGF) treatment with Ranibizumab. A consecutive series of 39 study eyes with centre-involving DME were included in this study. In all subjects, best-corrected visual acuity (BCVA) according ETDRS protocol, fluorescein angiography (FA), microperimetric macular sensitivity (MP) and Spectral Domain optical coherence tomography (SD-OCT) cross-sectional scans were obtained before treatment and after 3 monthly applied intravitreal Ranibizumab injections. Six different morphological qualities [IS/OS layer integrity, outer nuclear layer (ONL) cysts, ONL cyst size, inner nuclear layer (INL) cysts, blocking phenomenon and subretinal fluid] were graded of each cross-sectional OCT scan before and over the course of treatment by two experienced graders. Correlation analyses between functional and morphological parameters were obtained. Mean BCVA increased from 26 ± 14 to 33 ± 13 letters after 3 consecutive monthly applied Ranibizumab injections (p < 0.001). Central retinal thickness (CRT) decreased from 504 ± 144 to 387 ± 122 μm (p < 0.001). Over the course of treatment, IS/OS continuity improved (index: 0.56 ± 0.52 to 0.43 ± 0.49, Z = -1.415, p = 0.157), ONL cyst prevalence and size decreased significantly (index: 0.61 ± 0.44 to 0.56 ± 0.35, Z = -3.41, p = 0.001 and 1.75 ± 0.88 to 1.17 ± 1.05, Z = -4.02, p < 0.001), INL cyst prevalence decreased (index: 0.35 ± 0.52 to 0.28 ± 0.52, Z = -1.60, p = 0.109), blocking phenomenon did not change significantly (index: 00.12 ± 0.16 to 0.13 ± 0.15, Z = -0.45, p = 0.656) and subretinal fluid almost disappeared (index: 0.10 ± 0.24 vs. 0.00 ± 0.01, Z = -2.56, p = 0.011). Correlation analyses revealed highest significant correlations between ONL cyst prevalence and their size and CRT as well as BCVA and MP before treatment and over the course of treatment. ONL cysts and their size as morphological parameters correlate with retinal function measured with BCVA and microperimetry before and over the course of anti-VEGF therapy with Ranibizumab in patients with DME.