Posterior internal ophthalmomyiasis. Identification of a surgically removed Cuterebra larva by scanning electron microscopy.

The clinical presentation of an 11-year-old boy with unilateral posterior internal ophthalmomyiasis is described. Ophthalmoscopy of the affected eye in this individual disclosed characteristic subretinal depigmented linear tracks and a larva within the vitreous. The intravitreal larva was retrieved successfully by pars plana vitrectomy and identified as the first instar of Cuterebra sp. (rodent botfly) by scanning electron microscopy. This was done by examining the external features of the larva by scanning electron microscopy and comparing them to scanning electron micrographs that were prepared on other first instar larvae of flies known to be implicated in internal ophthalmomyiasis. The study demonstrates the usefulness of scanning electron microscopy for taxonomic identification of fly larvae. Since even a small fragment of these organisms may contain characteristic features of external morphology, scanning electron microscopy may be useful in cases where the specimen is damaged or incomplete.