Myiasis is the infestation of the body by the larval forms (maggots) of dipterous flies. Ophthalmomyiasis or ocular myiasis refers to the inflammations that involve the eye and ocular adnexa. This may be external, internal, or orbital. Less than 5% of human myiasis cases involve eye. Ophthalmomyiasis varies in severity, ranging from simple irritation to complete destruction of the orbit. The condition is often misdiagnosed as an acute conjunctivitis. Globally, so far, most cases have been reported from rural areas. Here, we present 2 case reports. Both patients belonged to an urban area. The larvae were successfully removed, and both cases are being followed. These cases show that this infection is probably more common in urban areas than reported.
Keywords: Eye, ophthalmomyiasis, urban
Members of cyclorhabid, mainly Sarcophaga and Oestridae Diptera, may produce myiasis in countries with poor hygiene and abundant flies. The genus Oestrus includes the cosmopolitan well-known sheep nasal botfly, the Oestris Ovis. The larva resides in tissues, head-sinuses, throat, or intestine of higher mammals and cause an irritation by curved mandibular barbs and body spines. An infection occurs when the adult female fly strikes the body tissues.  Ophthalmomyiasis externa, if not managed promptly, can lead to a fatal condition called ophthalmomyiasis interna, caused by penetration of ocular globe by larvae.  This has been reported from Libya, Afghanistan, Oman, Russia, Serbia, Africa, Iran  and in India from, Allahabad,  Tamilnadu,  North India,  western UP;  the first case in India was reported by Eliot.  To the best of our knowledge, this is the first case report from this part of India. Globally, the disease has been mostly reported from rural areas and in patients with history of contact with sheep or goats.  The present cases, however, had no such history, thus making these cases unique.
A 35-year-old software professional from Noida, U.P reported to the emergency with history of a foreign body falling in his right eye followed by irritation, redness, and watering. He was administered saline wash. He reported in the eye OPD the next day saying that he had observed something crawling in his right eye.
On examination under magnification, a number of white larvae with black tips were observed crawling in the right eye conjunctival sac. The conjunctiva was congested, and minimal mucopurulent discharge was present in the sac.
Eight of these larvae were removed under topical anesthesia with the help of forceps and sent to the lab for identification and classification. Two more larvae were removed the same day in the evening, and 2 more were removed after 2 days. In the meantime, he was advised an instillation of moxifloxacin ophthalmic solution.
The patient is still under follow-up.
A 24-years-old male, again a Noida resident, reported with irritation, redness, and watering right eye. The patient had used ciprofloxacin eye drops four to five times for this.
On examination, the conjunctiva was congested with mucopurulent discharge. Two larvae were observed crawling on the upper tarsal conjunctiva, which were removed under topical anesthesia.
The patient was advised antibiotic instillation and follow-up.
Both these cases presented within 3 days of each other.
Macroscopically, the larvae were 1-2 mm in length and motile. These were identified as larvae of Oestris Ovis on the basis of typical morphology [Figure 1] and [Figure 2].
Oestrus ovis (sheep nasal botfly) is the commonest cause of human myiasis, though domestic fly (Musca domestica) and cattle botfly (hypoderma) are other causes.  The gravid adult female fly swarms around the head of the animals and ejects the first-instar larvae on to the nostrils of the host. The larvae mature in the mucous membrane of the nasal cavities are sneezed out of the nostrils and they pupate in the soil. Adults then emerge from the pupae. Occasionally, due to an aberration in the life cycle, man becomes the intermediate host, with the eye being the site of infestation.  However, man is increasingly becoming a host and not a non-compromised host as suggested earlier.  Typically, the botfly lays its eggs on the decaying organic material and also in open mucopurulent sores like conjunctival sac. Within 24 hours, these eggs hatch and produce larvae. A pair of enlarged oral hooks helps the larvae to anchor. The larvae though restricted to the conjunctiva and cornea may, at times, cause penetration. Treatment depends on the severity of ocular involvement. In case of an external ophthalmomyiasis, manual removal with forceps is ideal. Local antibiotics are used to suffocate the organisms, which facilitates manual removal and also prevents further penetration. Topical steroids can be given to reduce the inflammation. Since the larvae anchor to the tissue with the help of hooks, simple saline washing is not helpful. It is important for medical personnel to be aware of this condition to make timely diagnosis and to consider it in the differential diagnosis of acute conjunctivitis. Recognizing the condition promptly by proper history taking and examination followed by an immediate treatment not only reduces morbidity and the duration of discomfort, but also reduces the potential complication of opthalmomyiasis interna.
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[Figure 1], [Figure 2]