External ophthalmomyiasis by larvae of Oestrus ovis (sheep nasal botfly): Second case report from Sri Lanka

External ophthalmomyiasis is the invasion of superficial tissues of the eye by fly larvae of the order Diptera. We describe a case of acute conjunctivitis caused by first instar larvae of Oestrus ovis. This is the second such case reported from Sri Lanka. A 28-year-old male was admitted to the National Eye Hospital of Sri Lanka complaining of itching, redness, foreign body sensation and swelling of his right eye. On examination, visual acuity in both eyes was normal; conjunctival injection was noted in the right eye; and the presence of a few motile larvae were observed on the conjunctival surface. The patient recovered completely following the removal of six larvae and treatment with topical antibiotics. The morphological features of the extracted larvae were compatible with the first instar larva of Oestrus ovis. Early detection and removal of botfly larvae will help minimize ocular damage.