Visual acuity and foveal thickness after vitrectomy for macular edema associated with branch retinal vein occlusion: a case series

BACKGROUND: The mechanism by which vitrectomy improves macular edema in patients with branch retinal vein occlusion remains unclear, although intraocular levels of vascular endothelial growth factor have been suggested to influence the visual prognosis and macular edema. METHODS: A series of 54 consecutive patients (54 eyes) with branch retinal vein occlusion was studied prospectively. All patients underwent pars plana vitrectomy for treatment of macular edema. Best corrected visual acuity and retinal thickness (examined by optical coherence tomography) were assessed before and after surgery. The level of vascular endothelial growth factor in vitreous fluid harvested at operation was determined. Patients were followed for at least 6 months postoperatively. RESULTS: Both the visual acuity and the retinal thickness showed significant improvement at 6 months postoperatively (P = 0.0002 and P < 0.0001, respectively). The vitreous level of vascular endothelial growth factor was significantly higher in patients who showed less improvement of visual acuity compared with those who had a better visual prognosis (p = 0.0135). In contrast, a high vitreous level of vascular endothelial growth factor was associated with greater improvement of macular edema (p = 0.0064). CONCLUSIONS: These results suggest that the vitreous level of vascular endothelial growth factor might influence the visual prognosis and the response of macular edema to vitrectomy in patients with branch retinal vein occlusion.