Contributor: Gordon K. Klintworth
Ophthalmomyiasis externa (external ophthalmomyiasis) is a type of ophthalmomyiasis caused by the larvae of certain botflies, such as Oestrus ovis (Oestridae) which can invade penetrate the ocular mucous membrane. . It is rarely caused by Dermatobia hominis. The larvae can often be seen wiggling beneath the transparent conjunctival epithelium. The diagnosis of the responsible pathogen is most reliable when an entire larva is available for examination, especially when its spiracles are well preserved. Scanning electron microscopy of the external features of the larvae can permit identification because of the characteristic external features of each specimen. Myiasis many affects farmers, laborers, and beggars. Human involvement in some types of myiasis is favored by an association of poor personal hygiene and a proximity to infested animals. Because of international travel ophthalmomyiasis externa can be found in countries where the responsible organism is not endemic.