Contributors: A. Bawa Dass and Michael T. Trese
Familial exudative vitreoretinopathy (Criswick-Schepens syndrome, FEVR) is an uncommon inherited ocular syndrome resulting in development of blood vessels in the peripheral retina often accompanied by peripheral retinal traction and exudation. Fewer than 300 cases have been documented. Given that many patients may be asymptomatic, the actual frequency may be underestimated. Unlike retinopathy of prematurity, FEVR is familial and not related to persons with a premature birth or exposure to supplemental oxygen. Further accounts of  FEVR continued to suggest a vascular basis for the disease as well as divide its clinical presentations into stages. Peripheral retinal ischemia and preretinal neovascularization was confirmed using fluorescein angiography by Canny and Oliver in 1976. FEVR is a  genetically heterogeneous disorder with variable expressivity. Four types of FEVR are recognized: familial exudative vitreoretinopathy type I  (autosomal dominant), familial exudative vitreoretinopathy type II (X-linked recessive), familial exudative vitreoretinopathy type III (autosomal recessive), and familial exudative vitreoretinopathy type IV (autosomal dominant). They have different modes of inheritance.