Histologic Changes of Fibrovascular Membrane Associated With Proliferative Diabetic Retinopathy After Intravitreal Bevacizumab (Avastin®)

Recently, intravitreal bevacizumab (Avastin) injection has gained popularity as a potential treatment of intraocular neovascularization (CNV) associated with age related macular degeneration and diabetic retinopathy. The efficacy of the drug is thought to be related with its pharmacologic blockade of VEGF.

The purpose of this study is to determine the effect of the intravitreal bevacizumab on the fibrovascular membrane associated with proliferative diabetic retinopathy by objective histologic evaluation.

The patients scheduled for vitrectomy for tractional fibrovascular membrane due to proliferative diabetic retinopathy will be randomized into two treatment groups. The one will receive conventional vitrectomy and the other group will receive intravitreal bevacizumab injection one week before the scheduled vitrectomy. The fibrovascular membrane will be excised during surgery and fixated for histologic examinations. The expression of VEGF and PEDF, a potent inhibitor of angiogenesis, will be evaluated in the fibrovascular membrane by immunohistochemistry. The results will be compared between two treatment groups.