Eye Worms

Eye worms are parasitic infections caused by nematodes (roundworms) that invade the eye or surrounding tissues. Though rare, these infections can lead to discomfort, vision problems, and serious complications if left untreated. Eye worms are typically transmitted through insect bites, especially from deer flies. Recognizing symptoms early and seeking prompt medical attention is key to preventing lasting damage to the eye.

• Thelazia (Eye Worm): The most common type, often found in animals and sometimes humans, causing irritation, redness, and watery eyes.

• Loa Loa (African Eye Worm): A parasitic worm transmitted by deer flies, which can move across the eye, causing discomfort and swelling.

• Onchocerca volvulus: Causes river blindness; the larvae invade eye tissues leading to severe vision problems.

• Dirofilaria: Rarely infects the eye, causing inflammation and pain.

• Eye worm infections are caused by parasitic worms, primarily Loa loa (also called the African eye worm).

• These worms are transmitted to humans through the bite of infected deer flies or mango flies that carry the larvae.

• When the infected fly bites a person, the larvae enter the bloodstream and migrate to the eye and surrounding tissues.

• Poor sanitation and living in tropical regions with high fly populations increase the risk of infection.

• In some cases, infection can also result from exposure to contaminated water or soil.

Deer flies are the primary vectors of Loa loa eye worms. When an infected deer fly bites a human, it transfers larvae through its saliva into the bloodstream. These larvae mature and migrate through tissues, sometimes appearing in the eye. The flies typically breed in rainforest or humid environments, increasing the risk in such regions. Protecting against bites with repellents and clothing is essential in endemic areas to reduce the chances of transmission.

• Persistent redness and irritation in the eye

• Excessive tearing or watery eyes

• Sensation of something moving or crawling in the eye

• Eye pain or discomfort, especially when blinking

• Swelling or inflammation around the eyelids

• Blurred vision or difficulty seeing clearly

• Increased sensitivity to light (photophobia)

• Occasional discharge or mucus from the eye

• Feeling of dryness or grittiness in the eye

Persistent eye pain and itching are often the earliest signs of an eye worm infection. These symptoms may be mistaken for more common eye issues like allergies or conjunctivitis. However, when accompanied by a history of insect exposure or visible movement in the eye, these signs can indicate a parasitic presence and should not be ignored.

In some cases, the worm can be seen moving across the white part of the eye or under the eyelid. This can be alarming but is a clear indicator of a parasitic infection. The movement may be slow and accompanied by a crawling sensation. Seeing the worm is a medical emergency that requires professional extraction and treatment.

Treatment usually involves anti-parasitic medications like ivermectin or diethylcarbamazine (DEC), which help kill the worms. In cases where the worm is visible and causing discomfort, surgical removal may be necessary. Follow-up care is important to ensure all parasites are eliminated and to monitor for any complications, such as infection or vision changes.

Early diagnosis of eye worm infections significantly improves treatment outcomes. Prompt medical attention can prevent the parasite from causing lasting damage to the eye or spreading to other parts of the body. If you suspect an eye worm infection, especially after traveling to high-risk areas, consult an eye care professional immediately.