Ocular Histoplasmosisby Scott Pautler, MD
What is the ocular histoplasmosis syndrome? The OHS is a condition where abnormal blood vessels may grow under the retina causing blurred, distorted vision. The retina is a thin layer of delicate nerve tissue that lines the inside wall of the eye like the film in a camera. In the eye, light is focused onto the retina, which “takes the picture” of objects you look at and sends the image to the brain. What causes the ocular histoplasmosis syndrome? Most cases of OHS occur as a result of an infection by the fungus Histoplasma capsulatum. This organism is most common in the Ohio and Mississippi River Valley areas and usually causes a brief, “flu-like” infection. After the infection is gone, scars are left behind. Years later, scars under the retina may cause loss of vision by growing abnormal blood vessels. What are the symptoms of the ocular histoplasmosis syndrome? Decreased central vision is common. It may be most notable at near and is usually associated with distortion, which means straight lines appear wavy or crooked. Eventually, a permanent blind spot in the center of vision develops. What treatment is available? The main treatment for the abnormal leaking blood vessels involves medication injection and laser treatment in the office. Laser acts to seal the leaking blood vessels and has been proven in certain cases to limit permanent damage from OHS. However, laser does not restore the vision to normal. The laser, itself, usually causes a permanent blind spot in the vision, but it is a smaller blind spot than what is expected from OHS if left untreated. Also, the blind spot from laser is usually slightly away from the very center of vision so that it is easier to see around a blind spot from laser than a blind spot from untreated OHS. Visudyne photodynamic therapy is a treatment that may be used in cases of abnormal blood vessels growing under the center of the retina. Copyright © 1999-2010 Designs Unlimited of Florida
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