Subretinal angiostrongyliasis-induced optic neuritis

A 27-year-old Thai male presented with progressive visual loss and a membrane-like floater in the right eye that had persisted for 1 month. He had a history of eating raw foods, including snails. His initial visual acuity was counting fingers at 1 ft and he had a relative afferent pupillary defect. A movable larva with subretinal tracks was found in the subretinal space near a normal optic disc. Visually evoked potentials showed delayed latency, which indicated secondary retrobulbar optic neuritis. A diode laser was directly applied to the motile worm. The patient was subsequently prescribed oral prednisolone and albendazole. After treatment, his visual acuity was slightly improved at 2/60. Ocular manifestation is a very rare event resulting from parasitic infection. In only 1.1% of angiostrongyliasis cases is an Angiostrongylus cantonensis larva identified in the eye. Ocular angiostrongyliasis with optic neuritis may be secondary to mechanical injury and/or inflammatory reactions. Steroid treatment is recommended, although most patients have only slight visual improvement after treatment.