Learn the Symptoms of Parasitic Eye Infections

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Parasitic eye infections are classified as severe infections that affect the eye and surrounding structures. These severe infections can be caused by either a protozoan (single-celled organism) or a metazoan (multi-cellular organism). There are three common types of parasitic eye infections: acanthamoeba keratitis, ocular onchocerciasis, and ocular toxoplasmosis. Each of these parasitic infections are caused by different parasites, produce different symptoms, and each requires an individualized form of treatment.

Acanthamoeba Keratitis

Acanthamoeba Keratitis is commonly caused by amoeba found in contaminated fresh water sources. In some cases, this parasitic infection is attributed to the use of contact lenses and corneal trauma.

Symptoms of Acanthamoeba Keratitis include the sensation of a foreign body within the eye, ocular pain, and blurred vision. The corneal nerve can become enlarged as well. Other common symptoms of the parasitic infection include swelling in the eyes, itchy or red eyes, and watery eyes.

Treatment for Acanthamoeba Keratitis often involves a combination of surgery and prescribed medications. Ketaconazoles are prescribed to assist with ridding the eye of the parasite. A surgery, known as keratoplasty, is used to treat the parasitic infection as well.

Ocular Onchocerciasis

Ocular Onchocerciasis, more commonly known as river blindness, is a parasitic infection caused by Onchocerca volvulus, which is a water-borne nematode that can cause skin infections as well. This infection occurs when black flies, which are generally found near fast flowing rivers, bite humans. Those living in the poorest regions of the world and those who live near fast moving rivers have an increased risk for this parasitic infection.

Common symptoms of river blindness include red, itchy eyes, sensitivity to light, and damage to surrounding tissue. As the second leading cause of infectious blindness, prompt treatment is needed to maintain proper vision. An anti-parasitic is most often used to treat river blindness. With the use of the drug Ivermectin, the micro-filarial stage of the infection is eliminated.

Ocular Toxoplasmosis

Ocular Toxoplasmosis is the most common form of parasitic eye infection. A protozoan, known as Toxoplasma gondii, is responsible for this infection, which is spread through cat and human contact. Symptoms of Ocular Toxoplasmosis vary from person to person; however, common symptoms associated with the infection include floaters in the eye and blurred vision. This infection can remain inactive for prolonged periods of time, making it difficult to diagnose because symptoms do not appear while the infection is inactive.

While this infection remains dormant without producing symptoms, inflammation of the central retina eventually occurs, which is when a diagnosis is often made. Treatment for Ocular Toxoplasmosis involves a six week course using two medications: pyramethamine and sulfadiazine folinic acid. Due to the numerous side effects associated with these drugs, frequent blood tests are needed to monitor the toxicity levels of the drugs.


Cornea and External Diseases” Digital Reference of Ophthalmology

Ocular Toxoplasmosis” The Retina Center

Onchocerciasis” WD