In many parts of the world, parasitic infections of the eye are a major cause of blindness. The parasitesToxocara canis,Onchocerca volvulus,Taenia solium,Ancylostoma caninum, andCysticercus celulosaeall have been responsible for blinding ocular infections. The nematodesT. canisandToxocara catiare parasitic roundworms that infect dogs (toxocarosis), other canidae, and cats. Ocular toxocariasis is an uncommon worldwide infection caused by the nematode larvae ofT. canis, commonly found in dogs. Human transmission is usually via geophagia, the ingestion of food contaminated withToxocaraeggs, or contact with infected puppies, often resulting in devastating ocular or systemic effects. Ocular toxocariasis is typically a monocular disease of young children, and its clinical findings include posterior and peripheral retinochoroiditis, optic papillitis, and endophthalmitis. The inflammatory response created by ocular involvement may result in epiretinal membrane formation, traction retinal detachment, and combined traction-rhegmatogenous retinal detachment. Diffuse unilateral subacute neuroretinitis is another ocular parasitic infection that usually results in severe visual loss. Evidence suggests that diffuse unilateral subacute neuroretinitis is caused by a solitary unidentified nematode of two different sizes, but to date, only a small number of nematodes have been recovered from eyes affected with the infection. Diffuse unilateral subacute neuroretinitis occasionally can affect the fellow eye.