Vascularisation of the fetal retina is not complete until term. Retinopathy of prematurity is a condition of premature babies in whom the peripheral retina is avascular.
Those vessels present are very sensitive to oxygen and the terminal branches may constrict if levels are too high. In the early stages, the changes are reversible and normal development may ensue. Later, however, new vessels begin to proliferate from the constriction sites into the vitreous. They become covered in fibrous tissue so forming a fibrovascular membrane behind the lens. A tractional retinal detachment may occur. In severe cases, there may be impaired vision, large refractive errors particularly myopia, strabismus and even blindness.
The condition is usually bilateral.
Last reviewed 11/2020