| Detection & Diagnosis
Ocular Histoplasmosis Syndrome
Histoplasmosis is caused
by a fungus commonly found in the dust and soil of the Mississippi-Ohio River
Valley region. Approximately 62% of
the adult population living in this region are carriers. It affects men and women equally.
contracted by inhaling dust that carries the fungal spores.
Its effect on the body can vary widely in severity from one person to
another. Many carriers have no
symptoms at all, but those with mild exposure may experience flu-like symptoms
and mild respiratory infections. Histoplasmosis
is more likely to become a serious problem in people who already have a weakened
The fungus may affect the
eye by causing small areas of inflammation and scarring of the retina.
These are called “histo spots” and may be found in both eyes.
Their affect on vision depends on the location of the scars.
Scarring in the peripheral area of the retina may have little or no
impact on vision, while a central scar affecting the macula
may cause a prominent blind spot.
Most people with histo
spots in the retina are totally unaware of their presence unless the central
vision is affected. Studies
indicate that only about 5% of those with histo spots are at risk of losing
vision. Scientists have been unable
find a link between the patients with minor histo spots and those who develop a
severe loss of their central vision.
Many patients with histo
spots in their eyes have no symptoms. Others
may experience the following:
Ocular histoplasmosis is
detected with a dilated examination of the retina using ophthalmoscopy.
It is usually diagnosed based on its distinctive appearance and
usually requires no treatment except when abnormal blood vessels develop in the
central retina. For these
patients, laser treatment may be necessary.
In some cases, surgical removal of the tiny, abnormal vessels has been
Regular eye exams and routine use of an
Grid to monitor central vision is recommended for anyone with histo
Illustrations by Mark Erickson
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