Histoplasmosis occurs when airborne spores of the fungus Histoplasma capsulatum are inhaled. This microscopic fungus is found throughout the world in river valleys and soil where bird or bat droppings accumulate, is released into the air when soil is disturbed by ploughing fields, sweeping chicken coops, or digging holes.
Only a tiny fraction of the people infected with the histo fungus ever develops OHS, any person who has had histoplasmosis should be alert for any changes in vision similar to those described above.
In the United States, the highest incidence of histoplasmosis occurs in a region often referred to as the "Histo Belt," where up to 90 percent of the adult population has been infected by histoplasmosis.
The symptoms of histoplasmosis are often so mild that it can be confused as common cold. In fact, if you had histoplasmosis symptoms, you might dismiss them as those from a cold or flu, since the body's immune system normally overcomes the infection in a few days without treatment.
A serious form of histoplasmosis is life threatening. The signs become evident between three to 17 days after the exposure to the cause in the form of fever, chills, headache, muscle aches, dry cough and chest discomfort.
A form of laser surgery called photocoagulation is the only only proven treatment for OHS so far. In this treatment, a small, powerful beam of light destroys the fragile, abnormal blood vessels, as well as a small amount of the overlying retinal tissue.
The destruction of retinal tissue during the procedure can itself cause some loss of vision, this is done in the hope of protecting the fovea and preserving the finely-tuned vision it provides.
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