National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Ocular toxoplasmosis


Ocular toxoplasmosis is an infection in the eye caused by the parasite, Toxoplasm a gondii. Toxoplasmosis is the most common cause of eye inflammation in the world. Toxoplamosis can be acquired or present at birth (congenital), having crossed the placenta from a newly infected mother to her fetus. Most humans acquire toxoplasmosis by eating raw or undercooked meat, vegetables or milk products, or by coming into contact with infected cat litterbox or sandboxes. In humans, the infection usually causes no symptoms, and resolves without treatment in a few months. In individuals with compromised immune systems, Toxoplasm a gondii can reactivate to cause disease.[1]  

Reactivation of a congenital infection was traditionally thought to be the most common cause of ocular toxoplasmosis, but an acquired infection is now considered to be more common.[2] A toxoplasmosis infection that affects the eye usually attacks the retina and initially resolves without symptoms. However, the inactive parasite may later reactivate causing eye pain, blurred vision, and possibly permanent damage, including blindness. Although most cases of toxoplasmosis resolve on their own, for some, inflammation can be treated with antibiotics and steroids.[3][2]
Last updated: 12/5/2016
In individuals with a normally functioning immune system and mild symptoms that do not threaten the function of the eye, treatment may not be needed and symptoms may resolve within 4-8 weeks.[3][2] For cases in which there is a potential for vision loss, treatment may involve the use of anti-parasitic medications, steroids, and antibiotics. Typically, the anti-parasitic medication pyrimethamine is utilized in combination with the antibiotic sulfadiazine and corticosteroids. Other medications that have been used in individuals with ocular toxoplasmosis include the antibiotics clindamycin, azithromycin, and trimethoprim-sulfamethoxazole and the steroid dexamethasone.[2]
Last updated: 12/7/2016
The long-term outlook (prognosis) for ocular toxoplasmosis is dependent on what part of the eye is affected. Symptoms during an infection resulting in abnormal vision (blurriness, loss) are usually associated with involvement of the macula (the part of the eye needed for sharp, central vision) or the optic nerve. Vision loss may become permanent if a scar forms around the macula or if damage to the optic nerve occurs (optic nerve atrophy). If a scar forms around the optic disk (point of entry of the optic nerve in the eye), vision loss may be severe.[2]
Last updated: 12/7/2016

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • The American Academy of Ophthalmology Web site has an information page on Ocular toxoplasmosis. Their Web site is dedicated to educating people about eye diseases and conditions and the preservation of eye health.
  • The American Association for Pediatric Ophthalmology and Strabismus provides a patient information sheet on Ocular toxoplasmosis. Click on the link to view this information.
  • You can obtain information on this topic from the Centers for Disease Control and Prevention (CDC). The CDC is recognized as the lead federal agency for developing and applying disease prevention and control, environmental health, and health promotion and education activities designed to improve the health of the people of the United States.

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.

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  1. Wu L, Roy H, et al. Ophthalmologic Manifestations of Toxoplasmosis. Medscape. September 29, 2015; http://emedicine.medscape.com/article/1204441-overview#showall. Accessed 12/5/2016.
  2. Ozgonul C., Besirli C.G.. Recent Developments in the Diagnosis and Treatment of Ocular Toxoplasmosis. Ophthalmic Research. October 11, 2016; https://www.ncbi.nlm.nih.gov/pubmed/27723657.
  3. Toxoplasmosis. American Association for Pediatric Ophthalmology and Strabismus. 10/2016; http://www.aapos.org/terms/conditions/106. Accessed 12/7/2016.