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Year : 2022  |  Volume : 34  |  Issue : 3  |  Page : 271-273

External ophthalmomyiasis: Slither sign in orb

Department of Ophthalmology, MGM Hospital, Navi Mumbai, Maharashtra, India

Date of Submission13-Dec-2020
Date of Decision02-Jan-2021
Date of Acceptance02-Jan-2021
Date of Web Publication22-Dec-2022

Correspondence Address:
Dr. Mamta Ramesh Agrawal
Department of Ophthalmology, New PG Hostel, MGM Hospital, Kamothe, Navi Mumbai - 410 209, Maharashtra
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/kjo.kjo_201_20

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Ophthalmomyiasis is the myiasis of the eye, a relatively rare condition characterized by infestation of ocular and orbital tissues with fly larvae. Oestrus ovis being the most common causative organism. It typically occurs in shepherds and farmers in rural areas. The clinical symptoms depend on the extent of tissue invasion, which may include conjunctivitis, haemorrhage or ulceration. We report a case of 20 y/M who presented to us with foreign body sensation and watering in right eye since morning, and redness since 1 day. His visual acuity in right eye was 6/9 and in left eye was 6/6. On slit lamp examination, anterior segment of right eye revealed lid oedema, mucopurulent discharge, papillae, conjunctival congestion and moving larvae about 15-20 in number were seen on cornea and conjunctiva. Rest was unremarkable. Causative larvae were removed with forceps under topical anaesthesia followed by instillation of antibiotic eyedrop. The causative larvae were sent for microbiological examination and were identified as the first stage larvae of Oestrus ovis, the sheep nasal bot fly. Very few cases of external ophthalmomyiasis have been reported from urban areas of Maharashtra in India.

Keywords: External ophthalmomyiais, Oestrus ovis, urban area

How to cite this article:
Agrawal MR, Ramakrishnan RA, Gandhi PH, Choudhary A. External ophthalmomyiasis: Slither sign in orb. Kerala J Ophthalmol 2022;34:271-3

How to cite this URL:
Agrawal MR, Ramakrishnan RA, Gandhi PH, Choudhary A. External ophthalmomyiasis: Slither sign in orb. Kerala J Ophthalmol [serial online] 2022 [cited 2023 Feb 2];34:271-3. Available from: http://www.kjophthal.com/text.asp?2022/34/3/271/364718

  Introduction Top

Ophthalmomyiasis, a rare ailment, is the myiasis of the eye, marked by fly larvae infestation of ocular and orbital tissues. Conducive organisms include Oestrus ovis, Calliphora, Sarcophaga, Lucilla, etc. Most commonly, O. ovis is the causative organism of ophthalmomyiasis. It can occur in three forms: external (larvae deposited on the ocular surface), internal (larvae penetrates the globe), and orbital (reaches orbital structures).[1] Orbital ophthalmomyiasis is the most damaging type.

It is predominantly seen in rural areas, in shepherds, and farmers. Predisposing factors include ocular infections, ocular injuries, old age, debilitation, and poor general health. The clinical features depend on the level of tissue invasion, which includes conjunctivitis, hemorrhage, and ulceration. It may cause blindness rarely.[2] Many countries including Afghanistan, Pakistan, the Caribbean, Kuwait, Iraq, The United States, Canada Libya, Tunisia, Russia, and India have reported cases of ophthalmomyiasis. In India, cases have been reported from Allahabad, Tamil Nadu, Western UP, and North India; Eliot reported the first case in India.[3]

Here, we report a case of external ophthalmomyiasis, causative organism being O. ovis at a tertiary care center in an urban area.

  Case Report Top

A 20 years old male presented to ophthalmology outpatient department (OPD) with chief complaint of foreign-body sensation and watering in the right eye since morning and redness since the previous night. He also complained of something going into the right eye while sitting beneath the tree the previous night followed by which he started experiencing the above symptoms. There was no history of ocular trauma, procedure, and systemic illness.

His visual acuity in the right eye was 6/9 and in the left eye was 6/6. On slit-lamp examination, anterior segment of the right eye revealed lid edema, mucopurulent discharge, papillae, conjunctival congestion, and moving larvae about 15–20 in number and 2–3 mm in size were seen [Figure 1]a and [Figure 1]b. The rest was unremarkable. Fundus was within normal limits. In the left eye, both anterior and posterior segment was normal.
Figure 1: (a) and (b) showing presence of larvae seen on cornea and conjunctiva in the right eye

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Topical anesthetic drop was instilled in the right eye, and the causative larvae were removed with forceps, followed by instillation of antibiotic drop.

The causative larvae were sent for microbiological examination. On macroscopic examination, the worms were milky white maggots of about 2 mm in size. Microscopy revealed spindle-shaped skeleton with multiple segments. A pair of sharp, dark brown oral hooks was attached to the internal cephalopharyngeal skeleton, and tufts of numerous brown hooks were on the margins of each body segment. They were identified as the first stage larvae of O. ovis, the sheep nasal bot fly [Figure 2].
Figure 2: showing microscopic picture of Oestrus ovis

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The patient was advised to apply eye ointment Azithromycin twice a day, eye drop carboxymethylcellulose eight times, and eye drop moxifloxacin 0.5% six times topically in the right eye. On follow-up next day, he was symptomatically better. There was no evidence of larvae, only papillae and mild congestion was seen. He was advised to continue the same treatment and follow-up after 1 week. The patient was referred to ENT OPD, and there was no evidence of the presence of parasites in the nasal cavity. On follow-up after 1 week, the symptoms subsided, and the vision in the right eye improved to 6/6.

Anterior segment and fundus examination of both the eyes were within normal limits.

  Discussion Top

Ophthalmomyiasis is a relatively rare condition characterized by infestation of orbital and ocular tissues with fly larvae. It is uncommon in developed countries but is common in underdeveloped area of the world due to poor standard of living and poor hygiene.

It can occur in three forms: external ophthalmomyiasis, in which larvae are deposited on the ocular surface, internal ophthalmomyiasis, in which larvae penetrate the globe, and orbital ophthalmomyiasis, in which the larvae reach orbital structures and cause damage.[1] Orbital ophthalmomyiasis is the most serious type.

Several offending species have been identified including the human botfly (Dermatobia hominis), latrine fly (Fannia), house fly (Musca domestica), and cattle botfly (Hypoderma), but O. ovis, or the sheep botfly, is the most common cause of human ophthalmomyiasis. Natural hosts of the fly O. ovis are animals such as sheep, cattle, deer, horse, and rodents and accidental host is humans. The female O. Ovis retains her eggs within her body until they hatch, and then typically deposit her larvae into the nostrils of sheep and goats. When they occur in the human eye, larval infections are usually restricted to the conjunctiva and cornea. O. ovis infections have also been reported in the human nose and pharynx. In human host, O. ovis larvae can survive only up to 10 days.

The clinical course of ocular myiasis is still inconclusive. Severity of clinical features varies from mild irritation to complete orbit destruction.[4] External ophthalmomyiasis is rarely seen in humans. Internal ophthalmomyiasis is less common worldwide than external ophthalmomyiasis, wherein the larvae enter vitreous and may reach subretinal fluid. OCT imaging through the tracks has reportedly revealed subretinal tunnels.[1]

Social history is essential in the evaluation of ophthalmomyiasis, as the patient may have a recent history of close contact with sheep or goats.

In cases of external ophthalmomyiasis, the patient may report a history of sudden onset of pain, burning, itching, watering, foreign-body sensation, swelling, etc., Slit-lamp examination may reveal small translucent larvae up to 5 mm in length on the conjunctiva. The patient may develop mucopurulent conjunctivitis, or rarely, corneal ulcer or keratitis. Most cases reported are of catarrhal conjunctivitis in the literature. A rare association of O. ovis ophthalmomyiasis with keratitis has been reported.[4] Therefore, it is an important differential diagnosis of acute conjunctivitis. Some organisms can penetrate into the eye such as D. hominis, Hypoderma bovis, and rarely O. ovis. Therefore, urgent removal and identification of the causative organism is necessary.[5] Management includes mechanical removal of larvae using forceps or cotton swab under local anesthesia and instillation of topical antibiotics and lubricants.

To the best of my knowledge, external ophthalmomyiasis is rarely reported from urban areas of Maharashtra.

  Conclusion Top

External ophthalmomyiasis is a relatively rare condition in urban areas. Based on its pathology and clinical course, immediate removal of causative organism is essential to prevent complications such as internal ophthalmomyiasis with potential visual consequences.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Available from: https://eyewiki.aao.org/Ophthalmomyiasis. [Last accessed on 2020 Dec 12].  Back to cited text no. 1
Ranjan R, Jain A. External ophthalmomyiasis. Oman J Ophthalmol 2014;7:160-1.  Back to cited text no. 2
[PUBMED]  [Full text]  
Goel H, Tangri R, Kaur R, Jain J. Two case reports of ophthalmomyiasis externa caused by Oestrus ovis larvae. Ann Trop Med Public Health 2012;5:549-50.  Back to cited text no. 3
  [Full text]  
Reddy A, Ganeshpuri S, Garg P, Sreejith R. Oestrus ovis ophthalmomyiasis with keratitis. Indian J Med Microbiol 2010;28:399.  Back to cited text no. 4
[PUBMED]  [Full text]  
Rao S, Radhakrishnasetty N, Chadalavada H, Hiremath C. External ophthalmomyiasis by Oestrus ovis: A case report from Davangere. J Lab Physicians 2018;10:116-7.  Back to cited text no. 5
[PUBMED]  [Full text]  


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