External ophthalmomyiasis.

Sir,

Ophthalmomyiasis, infestation of ocular and orbital tissues with fly larvae (maggots), is a rare but relatively more common condition in under-developed world due to poor living and hygiene standard.[1] Affected patients are usually unattended old persons and suffer from debilitating underlying conditions. It can also affect persons living or working in close proximity to livestock, children, and even non-compromised hosts rarely.[2]

Case Report

A 72-year-old man was brought to the ophthalmology department with complaints of ulceration, severe pain, and discomfort over left eye for the last 7 days. According to his attendant, the patient was living alone in his village home. The patient was unable to walk properly and was living a sedentary life due to multiple joint-related discomforts. His mental status was normal and he gave a history of fall about 10 days back with minor trauma to left upper eyelid.

On initial examination, the patient was restless and was not able to open his left eye. There was a large excoriated ulceration over left eye with erythema and oedematous swelling of periorbital tissues. On thorough examination, it was only upper eyelid which was severely necrotized with numerous maggots moving to and fro in the necrotic tissue [Figures 1 and 2]. On retracting the upper eyelids with difficulty, the palpebral conjunctiva and other ocular tissues were intact. Orbital computed tomography (CT) scan revealed intact globe with no disturbance of periocular tissues and periorbital sinuses. Thus, orbital invasion was ruled out and the patient was admitted as a case of external ophthalmomyiasis.

Figure 1

Examination of left eye revealing large excoriated ulcer with surrounding erythema and edematous swelling in upper eyelid and central necrotized tissue with numerous motile maggots while examination of the anterior/posterior segments of the affected eye was unremarkable

Figure 2

Magnified view showing maggots

On the day of admission, the patient was taken to the minor operation theater. After instillation of topical xylocaine (4%) drops, all necrotic tissues and over 100 maggots were removed. Maggots were removed by catching them with fine smooth forceps. During removal, maggots were tending to migrate into the deeper tissues and soft tissues of forehead. Daily dressing was done to remove all residual larvae until fourth day when they were no more. Every day, after removal of larvae, cleaning was done with betadine solution and antibiotic ointment was applied. Systemic antibiotic and analgesic were also prescribed for 5 days. Swelling and redness reduced gradually and granulation tissue started to appear in about a week [Figure 3].

Figure 3

Newly formed granulation tissue (9th day image) following mechanical removal of maggots with necrotized tissue and daily dressing with betadine solution and application of antibiotic ointment

Discussion

Ophthalmomyiasis is divided into orbital, internal, and external, based on site of larval infestation.[3] Orbital and internal ophthalmic myiasis is caused by larva with invading habits leading to blinding manifestations. External ophthalmic myiasis refers to superficial infestations of ocular tissue such as conjunctiva and eyelids. But external ophthalmomyiasis caused by invading larva can also result in serious complications such as corneal ulcer, iridocyclitis, globe invasion, endophthalmitis, and even blindness.[4] However, none of these complications were encountered in our patient and the invasion was limited to upper eyelid and soft tissue of forehead only.

There are three families of flies which cause ophthalmic infestation, i.e. Oestridae, Calliphiride, and Sarcophagidae.[15] Ophthalmomyiasis is usually caused by larvae of the sheep nose botfly (Oestrus ovis) while human botfly (Dermatobia hominis) is less commonly involved.[2] All these flies are oviparous and eject their eggs on necrotic dead tissue, which hatch to larvae (maggots). If possible, exact taxonomic classification of these larvae gives idea about potential risk of intraocular complications. Removed larvae should be preserved in 70% alcohol and sent to specialist for examination.

Except mechanical removal of these larvae, there is no other therapy described.[46] In external myiasis, larvae can be removed by using fine forceps. Topical anesthetic is used to reduce the motility of migrating larvae.[1] Severe orbital myiasis may require exenteration. However, in internal myiasis larvae can be destroyed by laser photocoagulation or removed by pars plana vitrectomy.[7]