Anatomic Response to Intravitreal Dexamethasone Implant and Baseline Aqueous Humor Cytokine Levels in Diabetic Macular Edema

PURPOSE. To determine whether baseline cytokine aqueous humor (AH) levels are associated with diabetic macular edema (DME) anatomic response to dexamethasone intravitreal implant (DEX) injection. METHODS. This was a prospective cohort study of DME cases receiving DEX treatment. Seventy patients were recruited with center-involving DME with spectral-domain (SD) optical coherence tomography (OCT) detection of central macular thickness (CMT) >= 300 mu m on macular cube 518 x 128-mu m scan protocol (Cirrus SD-OCT). DEX injection and anterior chamber tap to obtain an AH sample were performed at the same time. Multiplex immunoassay was carried out for interleukin (IL)-1 beta, IL-3, IL-6, IL-8, IL-10; monocyte chemoattractant protein (MCP)-1; interferon gamma-induced protein (IP)-10; tumor necrosis factor (TNF)-alpha; and vascular endothelial growth factor (VEGF). A follow-up visit and OCT exam were undertaken 6 to 8 weeks afterward. The association between AH cytokine baseline levels and change in CMT and macular volume (MV) was defined as main outcome measure. RESULTS. Multivariate linear regression analysis showed a higher decrease in MV to be associated (R-s of 0.512) with four baseline items: higher MCP-1 (beta = -0.4; P = 0.028), higher CMT (beta = -0.003; P = 0.024), decreased visual acuity (beta = -0.7; P = 0.040), and a diffuse retinal thickening (DRT) OCT pattern (beta = -1.3; P < 0.001). Logistic regression found DRT also to be associated with higher odds of a good MV response (odds ratio, 31.96; 95% confidence interval [CI] 7.11-143.72; P < 0.001). CONCLUSIONS. Even though visual acuity response and anatomic effect are not always correlated in DME, we found that baseline elevated MCP-1 AH levels and DRT pattern were biomarkers that predicted a future favorable anatomic response to DEX.