Familial exudative vitreoretinopathy

Familial exudative vitreoretinopathy, often shortened to FEVR, is a hereditary eye disorder in which the blood vessels at the outer edge of the retina do not develop fully. The retina is the light-sensitive tissue lining the back of the eye, and the reduced blood supply at its periphery causes chronic ischemia that can slowly damage it. Severity varies widely, even within one family: many affected people never have vision problems, while others develop leaking vessels, fluid under the retina, folds, tears or retinal detachment, which can lead to vision loss and blindness. Strabismus and a visible whiteness in the pupil (leukocoria) are also possible. Variants in the FZD4, LRP5 and NDP genes cause most cases, and some people with LRP5 variants also have reduced bone density. Inheritance is most often autosomal dominant, but can be autosomal recessive or X-linked recessive depending on the gene. How common it is remains unknown.