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Purpose: To evaluate the effects of an intravitreal ranibizumab (IVR) injection on the retinal microcirculation of eyes with macular edema secondary to a branch retinal vein occlusion (BRVO). Methods: Twenty-six eyes of 26 patients with macular edema due to a BRVO that had received a single IVR injection (0.5 mg/0.05 mL) were studied. The retinal microcirculation was assessed by laser speckle flowgraphy (LSFG) using the mean blur rate (MBR) and relative flow volume (RFV). The size of the retinal arteries and veins surrounding the optic nerve head were measured separately. All of the examinations were made before, and at 1 week, and 1 and 2 months after the IVR. Results: The visual acuity improved significantly, and the mean central macular thickness decreased significantly during the follow-up period (both P < 0.001). The mean MBRall and MBRtissue decreased significantly at 1 week and 1 month after the IVR (both P < 0.001). The total RFV of the arteries and veins decreased significantly at 1 week and 1 month after the IVR injection in the occluded and nonoccluded quadrants (all P < 0.001). The width of the arteries and veins in the LSFG images decreased significantly at 1 week and 1 month after the IVR injection (P < 0.001). Conclusions: An IVR injection leads to a transient vasoconstriction of the retinal arteries and veins and a reduction of the retinal blood flow and velocity in both the occluded and nonoccluded quadrants. The changes in retinal microcirculation might be related to the improvement of the macular edema and vision.
Fukami et al. (Thu,) studied this question.