What is Histoplasmosis?

What is Histoplasmosis?

Histoplasmosis is a disease that is caused by spores the fungus -histoplasma capsulatum. This fungus is found in places where there is an accumulation of bird (chicken) and/or bat droppings. When the ground is dug up for planting crops, chicken coops are swept or holes are dug, the spores of the fungus are released and can be breathed in through the lungs. This causes mild flu or cold-like symptoms and the body normally fights off the infection within a few days without treatment. It is estimated that between 60% and 80% of the people who live in the Ohio, Tennessee and Mississippi River Valley areas have been exposed.

What is Ocular Histoplasmosis Syndrome?

Ocular histoplasmosis syndrome (OHS) develops in a very small percentage of people that develop Histoplasmosis. In some, dur- ing the infection with histoplasmosis, the fungus can travel from the lungs to the choroid (the vascular structure under the retina). Once in the choroid, the fungus causes scarring in the choroid and pigmented layers of the eye. This scarring appears as small punched out yellow spots at the back of the eye. As the scarring occurs, there usually are no symptoms at all. The scarring is usu- ally only discovered later during a routine eye exam.

How does Ocular Histoplasmosis affect my vision?

Most retinal scars from histoplasmosis do not cause any problems. Some scars that are close to the center of the eye (in the macula) can start to bleed and cause vision loss. The histoplasmosis scars in the macula can lead to new blood vessel growth (neovascularization). Neovascularization causes vision loss because the ab- normal blood vessels that are formed leak fluid and blood. If left untreated, the neovascularization can form a fibrovascular scar causing permanent vision loss.

How is Ocular Histoplasmosis Syndrome diagnosed?

OHS is usually diagnosed by a dilated eye exam and confirmed through the use of specialized testing. Optical coherence tomography (OCT) is used to quantify how much swelling or damage there is to the retina.

How is Ocular Histoplasmosis Syndrome treated?

Ocular histoplasmosis usually requires no treatment. Antifungal medica- tions are not useful. Histoplasmosis results in scars in the eye, there is no active fungal infection in the eye. In the rare case where abnormal blood vessels develop, laser or medication is used to stop the bleeding and pre- serve the vision. If the area of bleeding is small and located outside of the central vision the bleeding may be controlled using laser treatment. If the bleeding is close to the center of the vision medications are used. All the medications used to treat macular degeneration have also been found to work with ocular histoplasmosis The medications need to be given by an intraocular injection and need to be repeated.

What is the long-term effect of Ocular Histoplasmosis Syndrome on my vision?

Usually the prognosis is excellent. If there are histoplasmosis scars in the macula it is important to have regu- lar eye exams to monitor the disease. If bleeding occurs in the macula, earlier treatment usually results in a better outcomes. With intraocular injections of medication most patients have an improvement in the vision although permanent vision loss can occur.

If you have been diagnosed with Histoplasmosis and want to be monitored or have been exposed and want to be examined, please call our offices today!