Pretreatment Clinical Variables Associated With the Response to Intravitreal Bevacisumab (Avastin) Injection In Patients With Persistent Diabetic Macular Edema

Abstract

Background: The purpose of the study is to determine whether the pre-treatment clinical systemic variables and optical coherence tomographic (OCT) findings are associated with the subsequent response to the intravitreal Bevacisumab (IVB) in eyes with diabetic macular edema (DME).Patients and Methods: 38 patients (45 eyes) with refractory diabetic macular edema. ; 16 females, 22 males and mean age was 57.5 year. All patients had DME not responded to other treatments. Complete eye examination; 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 0.05mL =1.25 mg Bevacizumab (Avastin; Genentech, Inc.,San Francisco, CA), and followed up for 3 months. The pre and post-operative follow-up data were analyzed by Student-t test and Mann-Whitney test for two main outcome measures; visual acuity (LOGMAR) & central foveal thickness (CFT) changes over a period of three months, and data include demographic factors, type, duration and 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 visual acuity and 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 µ (SD ± 127.36), 394.95 µ (SD ± 138.03) and 378.32 µ (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 LogMAR and CFT values before and after IVB injection showed significant statistical correlations (p< 0.05) in relationship to variables of diabetic duration, diabetic control (HbA1c), and OCT pattern of macular edema, serum creatinine and cholesterol.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 Bevacisumab injection.Key words: CSME, Bevacisumab (Avastin), Systemic factors and OCT,BCVA= BEST CORRECTED VISUAL ACUITY.