Pretreatment clinical variables associated with the response to intravitreal bevacizumab (Avastin) injection in patients with persistent diabetic macular edema.

BACKGROUND: The purpose of the study is to determine whether the pre-treatment clinical systemic variables and optical coherence tomography (OCT) findings are associated with the subsequent response to the intravitreal bevacizumab (IVB) in eyes with persistent diabetic macular edema (DME).

DESIGN: Prospective, interventional non-comparative case series study.

METHODS: 38 Patients (45 eyes) with refractory diabetic macular edema; 16 females, 22 males with a mean aged 57.5 year. All patients had persistent DME not responded to other forms of treatments. Complete eye examination; best corrected visual acuity (BCVA) (represented as LOGMAR for adequate statistical analysis), slit-lamp exam, intraocular pressure measurement, stereoscopic biomicroscopy of the macula, and morphologic patterns of diabetic macular edema demonstrated by OCT. All patients had intravitreal injection of 0.05 mL = 1.25 mg bevacizumab (Avastin; Genentech, Inc., San Francisco, CA), and were followed up for 3 months. The pre and post-injection follow-up data were analyzed by Student-t test and Mann-Whitney test for two main outcome measures; visual acuity (LOGMAR) and central foveal thickness (CFT) changes over a period of three months, and the data included demographic factors, type, duration and the control of diabetes mellitus (HbA1C%), grade of diabetic retinopathy, renal function (serum creatinine level), serum cholesterol, blood pressure control and previous treatment by focal laser and/or intravitreal triamcinolone injection.

RESULTS: The LOGMAR and central foveal thickness (CRT) improved in 30/45 eyes (67%) and 32/45 eyes (72%), respectively during a mean follow-up time of three months. The mean LOGMAR visual acuities were 0.64 (SD ± 0.34), 0.61 (SD ± 0.31) and 0.60 (SD ± 0.32) at pre-injection, at 1 month post-injection and at 3 months post-injection, respectively; but this mean increase in vision was statistically not significant (P value = 0.099). The mean foveal thicknesses were 444.95 μm (SD ± 127.36), 394.95 μm (SD ± 138.03) and 378.32 μm (SD ± 112.01) at pre-injection, 1 month post-injection and 3 months post-injection, respectively, this decrease in the foveal thickness was statistically significant (P value <0.001). The pre and post-injections values of the variables for diabetic duration, diabetic control (HbA1c) and OCT pattern of macular edema showed significant statistical correlations (P < 0.05) with LOGMAR only, however the values of the variables for serum creatinine and cholesterol show statistical correlation (P < 0.05) with both LOGMAR and CFT.

CONCLUSIONS: Chronicity and inadequate control of diabetes mellitus, nephropathy, hyperlipidemia and presence of vitreomacular attachment (VMA) are factors associated with poor vision progress after intravitreal bevacizumab injection.