Eye Parasites: Symptoms, Treatment, and Prevention

An eye parasite refers to a living organism that inhabits the human eye, deriving sustenance and shelter from its host. These organisms can range from microscopic single-celled entities to larger, visible worms. While residing within the ocular structures, parasites can disrupt normal eye function and cause a variety of health issues.

Common Eye Parasites and How They Spread

Acanthamoeba is a single-celled organism found widely in water, soil, and air. This amoeba causes Acanthamoeba keratitis, a severe eye infection particularly affecting the cornea, the clear front part of the eye. It is frequently linked to improper contact lens hygiene, such as rinsing or storing lenses with tap water, or swimming while wearing them.

Loa loa, also known as the African eye worm, is a helminthic parasite prevalent in West and Central Africa. Loiasis, caused by Loa loa, is contracted through repeated bites from infected deerflies (mango flies). Infected flies transmit microscopic larvae that mature and migrate throughout the body, sometimes becoming visible as they move across the eye’s conjunctiva.

Toxocara, a roundworm commonly found in dogs and cats, can cause eye infections. Ocular toxocariasis occurs when humans ingest eggs from contaminated soil, often through contact with animal feces. Once ingested, the larvae hatch in the intestines and can travel to various organs, including the eyes.

Onchocerca volvulus is a parasitic worm responsible for onchocerciasis, commonly known as river blindness. It is transmitted through repeated bites from infected blackflies, which carry microscopic worm larvae. The larvae penetrate the skin and can cause eye lesions, potentially leading to vision loss if they infect the optic nerve, cornea, or retina.

Thelazia, sometimes referred to as “eye worms,” are parasitic nematodes. These worms are often found in animals but can occasionally infect humans. They are transmitted through the bites of infected flies, such as deer flies or mango flies, which deposit larvae.

Recognizing Symptoms of Eye Parasites

Symptoms of eye parasite infections vary, and some individuals may experience no noticeable signs. When symptoms occur, they often involve discomfort and visual disturbances. These include eye pain, redness, or inflammation in or around the eye.

Other symptoms include excessive tearing, a feeling that something is in the eye, or sensitivity to light. Visual changes like blurred vision, impaired vision, or new “floaters” (small spots or lines in the field of vision) can also indicate infection. In severe cases, visible worms in the eye, retinal scarring, or corneal ulcers may develop.

Diagnosing and Treating Eye Parasite Infections

Diagnosing

Diagnosing eye parasite infections involves clinical evaluation and specific tests. An eye care professional conducts a comprehensive eye examination, which may include a slit-lamp examination to inspect the eye’s structures. Laboratory tests on eye samples, such as corneal scrapings or vitreous aspirates, confirm the parasite’s presence and type through microscopic examination.

Imaging studies, including Optical Coherence Tomography (OCT) and fundus photography, can help assess any damage to the retina and optic disc. Serological tests, like Enzyme-Linked Immunosorbent Assay (ELISA), also detect antibodies against specific parasites in the patient’s blood serum.

Treating

Treatment approaches depend on the specific parasite and infection severity. Medical treatment often includes antiparasitic medications, administered orally or topically as eye drops. Examples of such medications include pyrimethamine, ivermectin, and diethylcarbamazine, each chosen based on the parasite type. In some cases, particularly with larger worms, surgical removal of the parasite from the eye may be necessary to resolve the infection and prevent further damage.

Protecting Your Eyes from Parasites

Preventing eye parasite infections involves adopting hygiene practices and precautions, especially in areas where these parasites are more common. Proper contact lens hygiene is important for contact lens wearers. This includes using only sterile solutions for cleaning, rinsing, and storing lenses, and avoiding tap water, even for rinsing lens cases. It is also advisable to avoid swimming or showering while wearing contact lenses.

Practicing good hand hygiene, such as washing hands frequently with soap and water, especially before eating and after handling raw meat or animal waste, reduces the risk of ingesting parasite eggs. In regions where parasitic infections are prevalent, ensure all food is thoroughly cooked and drink water from clean, safe sources. Using insect repellent and wearing protective clothing can also help prevent bites from flies and other insects that transmit parasites.

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