Ocular and systemic predictive factors in the treatment of diabetic macular edema with bevacizumab

Aim: To determine the results of intravitreal bevacizumab (IVB) treatment in treatment-naive diabetic macular edema (DME) and the systemic and ocular biomarkers that affect the anatomical and visual (functional) response. Materials and Methods: The records of patients who received IVB treatment with a diagnosis of DME at the Retina Clinic of Ondokuz Mayıs University Faculty of Medicine Hospital between May 2021 and September 2022 were retrospectively examined. Patients with nonproliferative diabetic retinopathy (NPDR) and naive diabetic macular edema (DME), treated with 3 consecutive monthly doses of IVB, were included in the study. Demographic characteristics of the patients; peripheral blood before treatment (whole blood and biochemistry) parameters, visual acuity (BCVA) before and after treatment, intraocular pressure (IOP) and macular spectral domain optical coherence tomography (SD-OCT) findings were recorded. In SD-OCT, central macular thickness (CMT), ganglion cell layer thickness (GCT), thickness of the inner and outer retina layers (IRL and DRL), and central choroidal thickness (CCT) were recorded. Visual and anatomical responses of the patients were examined according to the CMT decrease and BCVA increase achieved with 3 consecutive monthly doses of IVB treatment. The effects of recorded systemic and ocular parameters on anatomical and visual response were investigated. Results: 48 eyes of 48 patients were included in the study. The average age of the cases was 64.02±8.48 years, 45.8% (22 people) were women and 54.2% (26 people) were men. The average duration of DM was 15.73±7.86 years, BMI was 29.38±4.66 kg/m2, and HbA1c was 9.1±2.1 mmol/mol. Compared to before treatment, BCVA (0.44 and 0.18 logMAR, p <0.001) and IOP (15 and 17.5 mmHg, p =0.040) increased significantly after treatment; SMK (427 and 312 µm, p <0.001), GHK (31.5 and 25 µm, p <0.001) and IRC (338.5 and 229.5 µm, p <0.001) were significantly reduced. Anatomical response was obtained in forty (83.3%) cases. Dry macula was obtained in eighteen (45%) cases. In the anatomically successful group, BCVA (0.48 and 0.18 logMAR, p ˂0.001) and IOP (15 and 17.5 mmHg, p =0.008) increased significantly after treatment compared to before; SMK (435.5±98.9 and 314.5±62.8 µm, p <0.001), GHK (33.3±11.8 and 25.1±8.7 µm, p <0.001), IRC ( 351.4±99.1 and 227.9±63.1 µm, p <0.001) and CCT (272.9±81.6 and 264.1±83.7 µm, p <0.001) were significantly reduced. WBC (8.27 and 6.69 µL/103, p = 0.049) was found to be higher in cases with anatomical response than in non-responders. Visual response was obtained in thirty-six (75%) cases. In the visually successful group, BCVA (0.48 and 0.15 logMAR, p <0.001) and IOP (14.5 and 17.5 mmHg, p <0.001) increased significantly after treatment compared to before; SMK 425.5 and 420.5 µm, p <0.001), IRC (329 and 223.5 µm, p <0.001) and GCC (30.5 and 24.5 µm, p <0.001) were significantly reduced. In visually responsive cases, BUN (33.9±12.08 and 22.6±8.7 mg/dL, p =0.005) was higher than in non-responders, and LDL (106.3±37.6 and 153.83±61.05 mg) /dL, p =0.002) was found to be low. While there was no risk factor affecting anatomical success in binary logistic regression analysis; Increased hemoglobin (OR =0.621 [0.40-0.951]; p =0.029) and hematocrit (OR =0.860 [0.741-0.99]; p =0.049) levels were positive prognostic factors for obtaining dry macula; It was determined that low BUN, LDL and high pre-treatment IOP were negative prognostic factors for functional success. Conclusion: Significant anatomical and visual success is achieved in the treatment of DME with intravitreal bevacizumab. While keeping hemoglobin and hematocrit levels high positively affects the success of treatment, low BUN, high LDL and pre-treatment IOP have negative effects. Key words: Bevacizumab, biomarker, diabetic macular edema, prognostic factor, optical coherence tomography.