What are the other Names for this Condition? (Also known as/Synonyms)

• Myiasis of Eye Orbit
• Myiasis of Orbit
• Ophthalmomyiasis Profunde

What is Orbital Myiasis? (Definition/Background Information)

• Myiasis is primarily a skin disease caused by several species of parasitic fly larva (of taxonomic order Diptera). The fly larvae (maggots) cause disease in humans and other vertebrate animals by feeding on the tissues. The infection is usually characterized by a painful, itchy, boil-like skin lesion that contains the parasite within it
• Orbital Myiasis is a very severe and potentially destructive form of ophthalmomyiasis (also termed oculomyiasis) that involves the eye orbit (orbital tissues). The orbit is the socket that houses the eyeball, protecting it from any external trauma
• The main risk factor for Orbital Myiasis is an underlying eyelid tumor or eye disease; other factors include advancing age and eye injury. The pathogens that cause wound myiasis commonly causes Orbital Myiasis, and include screw-worms and blow-flies
• Orbital Myiasis can cause severe and extensive orbital tissue destruction and serious complications, if not immediately addressed. Management of the condition involves removal of all larvae through appropriate surgical methods. Nevertheless, the prognosis depends on its severity, and is usually guarded

Who gets Orbital Myiasis? (Age and Sex Distribution)

• Orbital Myiasis is a rare condition that usually affects older adults, although individuals of any age category may be affected
• Both males and females are affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Orbital Myiasis? (Predisposing Factors)

The following are the risk factors for Orbital Myiasis: (mainly in the endemic regions)

• Advancing age and poor personal hygiene
• Having an open wound around the eye including eyelid tumors
• Pre-existent ocular conditions and infections
• Eye trauma that is left untreated 
• Lack of quality healthcare in the endemic regions
• Elderly adults, especially those with certain neurodegenerative conditions
• Poor mental health

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Orbital Myiasis? (Etiology)

• Orbital Myiasis is an uncommon parasitic infection commonly caused by any of the following species of insect larvae (among others):
  • Blow flies (Calliphoridae sp.)
  • New World screw-worm fly (Cochliomyia hominivorax)
  • Spotted flesh fly or screwworm fly (Wohlfahrtia magnifica)
• It is reported that wound myiasis involving the eye orbit can lead to Orbital Myiasis
• The condition may affect healthy individuals too

What are the Signs and Symptoms of Orbital Myiasis?

The signs and symptoms of Orbital Myiasis are dependent on the eye structures that are affected. In most cases, a single eye is involved. The signs and symptoms are often severe and may include the following:

• Eye inflammation 
• Prolonged eye pain, often for months and years that waxes and wanes
• Protrusion of eyeball
• Periocular edema (fluid in the eye) 
• Severe eye/orbital tissue destruction, including damage to the optic nerve
• Scarring of eye structures
• Severely impaired vision

How is Orbital Myiasis Diagnosed?

Orbital Myiasis is diagnosed on the basis of the following information. The diagnostic techniques used may vary based on the specific type of causative parasite.

• Complete physical examination and a thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests: Blood tests, such as complete blood count, which may show increased white blood cells
• General eye exam
• Slit-lamp examination
• Visual acuity test using a special and standardized test chart (Snellen chart)
• B-scan ultrasonography: Special ultrasound scan of the eye through a non-invasive diagnostic tool, to assess health of eye structures
• Optical coherence tomography (OCT) of eye: It is an ocular imaging technique to visualize the eye structure
• Imaging studies that may include CT and MRI scans of the eye/orbit

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Orbital Myiasis?

The complications of Orbital Myiasis may include:

• Severe emotional stress
• Secondary infection of the eye
• Extensive tissue destruction causing loss of eye (usually unilateral blindness)
• Myiasis may spread to other facial areas including to the brain
• Severe inflammatory response to dead larvae or parts of larvae, especially during its removal
• Sepsis, which can be life-threatening

How is Orbital Myiasis Treated?

The treatment for Orbital Myiasis reportedly varies based on the extent of damage to the eye and bone structures. The treatment may involve the following measures:

• Surgical excision and extraction of larvae, where feasible
• Laser photocoagulation to destroy the larvae, when possible
• Exenteration of the orbit to remove necrotic tissues and larvae if the condition is severe
• Topical steroids and mydriatics
• Prophylactic antibiotics and tetanus therapy
• Oral medications (ivermectin), if needed
• Surgical repair of eye structures, as needed
• Any dead larvae that does not further affect the eyeball or orbit may be left in place, per advice of the healthcare provider

Examination and identification of the larva following removal may be undertaken.

How can Orbital Myiasis be Prevented?

Orbital Myiasis may be prevented by considering the following measures:

• Maintaining basic personal and community hygiene and proper sanitation is highly important, particularly in the endemic zones
• Extra care should be taken while travelling to the endemic regions
• Ensure that wounds and skin ulcers are properly treated and dressed/covered
• Medical centers should provide fly screens on patient area doors, windows, and ventilators
• Use insect repellents to prevent the insects from entering residences
• The growth of adult flies must be effectively controlled and methods for eradication followed on a regular basis

What is the Prognosis of Orbital Myiasis? (Outcomes/Resolutions)

The prognosis of Orbital Myiasis varies from one individual to another but is mostly unpredictable.

• Successful outcomes depend upon speedy diagnosis and effective treatment
• A delayed diagnosis can result in severe complications including vision loss or fatalities, if vital structures are affected (such as the brain)

Additional and Relevant Useful Information for Orbital Myiasis:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/healthy-living/skin-disorders/