Purpose: To investigate whether there are systemic effects of unilateral intravitreal administration of bevacizumab on the untreated eye.
Methods: Twenty-three consecutive patients were enrolled in this study. All patients had a clinical diagnosis of bilateral diffuse diabetic macular edema with a central retinal thickness greater than 275 μm by Optical Coherence Tomography. They were treated with 2.5 mg bevacizumab intravitreally in the worst eye based on lines of vision, number of Early Treatment Diabetic Retinopathy Study letters, and central retinal thickness. The patients were observed every 2 weeks for 4 weeks. The Best Corrected Visual Acuity, central retinal thickness (μm), and macular volume (mm3) in the untreated eye measured by Optical Coherence Tomography were recorded at every visit.
Results: The Best Corrected Visual Acuity (mean ± SD) in the untreated eye was 34.46 ± 17.29. Early Treatment Diabetic Retinopathy Study letters at baseline, 38.31 ± 14.64 at 2 weeks, and 37.38 ± 14.59 at 4 weeks. The central retinal thickness in the untreated eye was 324.77 ± 76.51 μm at baseline, 319 ± 75.7 μm at 2 weeks, and 315.54 ± 78.2 μm at 4 weeks. The macular volume in the untreated eye was 8.99 ± 1.2 mm3 at baseline, 9.16 ± 1.26 mm3 at 2 weeks, and 8.99 ± 1.09 mm3 at 4 weeks. There were no statistically significant differences between any of the measurements.
Conclusion: Due to the lack of significant changes in the measurements of the untreated eye, the systemic effect of intravitreal bevacizumab seems to be unlikely. The small sample and low confidence of this pilot study prevent us to draw concrete conclusions.