This healthy 9YO boy was referred for an asymptomatic abnormal right optic nerve. There was no ocular family history. Vision was 20/150 OD and 20/30 in his normal OS.
Optos color RG imaging shows an anomalous right optic nerve, which is tilted and displaced superonasally from its apparent normal location. The fovea is markedly ectopic, located about 60 degrees inferotemporal to the nerve. Genetic testing revealed a heterozygous FZD4 variant of uncertain significance.
Learning Points:
Originally described by Criswick and Schepens (AJO 1969;58:578-594), familial exudative vitreoretinopathy (FEVR) can be inherited as an autosomal-dominant, recessive, or X-linked trait with high penetrance and variable expressivity. There are numerous genes associated with FEVR, including LRP5, FZD4, NDP, TSPAN12, ZNF408, CTNNB1 and KIF11 [Tao et al, Invest Ophthalmol Vis Sci 2021;62(15);4].
FEVR is characterized by peripheral temporal retinal avascularity, lipid exudation, neovascularization, tractional retinal detachment, and temporal dragging of the macula and retinal vessels. These findings are somewhat like those found with retinopathy of prematurity.
