Histoplasmosis is a fungal infection of the retina. This is an uncommon eye problem in the United States, but a common cause of blindness in undeveloped countries. It is more common in patients who grew up in the Mississippi Valley, and for those who grew up around birds, especially chickens, and in some cases cats. The infection is often passed from a mother to a developing fetus, as a result, most retinal scarring from the infection is present at birth.
Thankfully, active histoplasmosis infections are uncommon. The scarring from congenital infections is often noted during a routine examination of the retina, and has no immediate concern. In active cases, however, the fungus has a tendency to destroy the macula, or the area of central vision. Although rare, prior scarred areas can also form abnormal vessel growth which can lead to vision loss. This condition must be monitored closely for these unlikely, but devastating problems.