What is Ophthalmomyiasis?

Ophthalmomyiasis is a rare eye condition caused by the infestation of the eye or surrounding tissues with fly larvae (maggots). These larvae, typically from certain species of botflies or houseflies, invade the eye and its structures, leading to irritation, inflammation, and sometimes serious damage if left untreated. The condition may affect the external surface of the eye (external ophthalmomyiasis) or penetrate deeper into the eye (internal ophthalmomyiasis).

It is more commonly reported in tropical and subtropical regions, particularly in rural or livestock-associated environments, but it can occur anywhere under the right conditions.

Causes

Ophthalmomyiasis is caused by the accidental deposit of fly larvae in or around the eye. Specific contributing factors include:

• Fly Species: Common culprits include:
  • Oestrus ovis (sheep botfly)
  • Dermatobia hominis (human botfly)
  • Wohlfahrtia or Calliphora species (flesh flies and blowflies)
• Exposure to Flies:
  • Living or working near livestock, especially sheep or cattle
  • Traveling to areas with high fly populations
  • Poor hygiene or environmental sanitation
• Compromised Eye Health:
  • Pre-existing wounds, infections, or ulcers near the eye may attract flies.
  • People with eye injuries or open sores are at higher risk.
• Outdoor Activities:
  • Sleeping outdoors or working in fields without eye protection increases the chance of larval deposit.

Symptoms

Symptoms of ophthalmomyiasis depend on whether the infestation is external or internal:

External Ophthalmomyiasis:

• Redness and irritation of the eye
• Excessive tearing or watery eyes
• Sensation of something moving in the eye
• Swelling of the eyelid
• Eye discharge
• Pain or discomfort, especially when moving the eye
• Visual disturbance if the infestation spreads

Internal Ophthalmomyiasis:

• Severe eye pain
• Sudden vision loss or visual impairment
• Retinal damage or hemorrhage
• Inflammation inside the eye (uveitis or endophthalmitis)
• Floaters or flashes of light

In rare cases, the larvae can migrate deeper into the tissues, causing severe complications, including blindness.

Diagnosis

Accurate diagnosis is essential and typically involves:

• Physical Examination: Observation of live larvae in or around the eye using a slit-lamp microscope.
• Patient History: Recent travel to rural or endemic areas, contact with animals, or sudden onset of symptoms.
• Imaging:
  • Ultrasound of the eye: Useful in detecting internal larval movement.
  • CT or MRI: In severe or deep tissue involvement to assess orbital structures.

Types of Ophthalmomyiasis

• Ophthalmomyiasis Externa: Involves the eyelids, conjunctiva, or external parts of the eye.
• Ophthalmomyiasis Interna: Involves deeper structures such as the vitreous, retina, or optic nerve.
• Orbital Myiasis: When larvae invade the eye socket or orbit, potentially damaging surrounding bones and tissues.

Treatment

Prompt treatment is critical to avoid long-term complications. Treatment options include:

• Manual Removal: The primary method for external cases is the careful extraction of larvae using forceps or irrigation under local anesthesia.
• Surgical Intervention: In internal or severe cases, surgical removal may be necessary to prevent tissue damage or preserve vision.
• Antiparasitic Medication:
  • Ivermectin may be used in some cases to kill residual larvae.
• Topical Antibiotics or Steroids:
  • To reduce inflammation and prevent secondary infections.
• Oral Antibiotics: If there is tissue invasion or signs of systemic infection.
• Cold Compresses and Lubricants: To soothe irritation and support healing.

Prognosis

The prognosis depends on how quickly treatment is initiated:

• Excellent Outlook: In external cases where larvae are removed promptly, full recovery is common with little or no lasting damage.
• Guarded Prognosis: In internal cases, particularly with delayed treatment, there is a risk of permanent vision loss or damage to the eye’s internal structures.

Early diagnosis and complete larval removal are key to preventing serious complications.

Support and Resources

• Ophthalmologist Care: Patients should see an eye specialist immediately if infestation is suspected.
• Preventive Measures:
  • Use protective eyewear in fly-infested areas.
  • Practice good hygiene and wound care.
  • Keep living and animal areas clean to reduce fly populations.
• Travel Advice:
  • When visiting rural or tropical areas, avoid sleeping outdoors without protection.
  • Use insect repellent and netting.
• Educational Materials: Awareness campaigns in endemic areas can help reduce the risk of myiasis.