Patient getting an eye exam

At a glance: Ocular Histoplasmosis Syndrome (OHS)

  • Symptoms:

    Blurry vision, blind spots

  • Diagnosis:

    Dilated eye exam, fluorescein angiography

  • Treatment:

    Injections, laser surgery

What is OHS?

Ocular histoplasmosis syndrome (OHS) is an eye condition that can develop in people who have a lung infection called histoplasmosis. If you have histoplasmosis, the infection can move from the lungs into the eyes, leading to vision loss. 

Many people who have histoplasmosis don’t know it. If you’ve lived in places where histoplasmosis is common, like near the Ohio and Mississippi River Valleys, talk to your eye doctor about getting checked for OHS.

What are the symptoms of OHS?

OHS usually doesn’t cause any symptoms in the early stages. But over time, you may notice:

  • Straight lines looking crooked or wavy
  • Blind spots in your vision

What causes OHS?

Histoplasmosis — the lung infection that causes OHS — happens when people breathe in spores from a fungus called Histoplasma capsulatum. This fungus is often found in soil that has bird or bat droppings (poop) in it. Spores from the fungus can go into the air when someone moves the soil around, like while sweeping a chicken coop or plowing a field.

Experts think that people get OHS when spores spread from the lungs to the eye, and can lead to scars in the back of the eye. These scars are usually harmless, but sometimes they cause abnormal blood vessels to grow in the eye and lead to vision loss.

Am I at risk for OHS?

Anyone can get histoplasmosis — and OHS — if they’ve been to an area where histoplasma fungus lives. Histoplasma is particularly common in central and eastern parts of the United States, like near the Ohio and Mississippi River Valleys. In fact, many people who live in these areas have histoplasmosis and don’t know it.

Certain groups are at higher risk of having histoplasmosis turn into OHS, including:

  • People with weakened immune systems — for example, people with HIV/AIDS or people taking certain medicines
  • Babies
  • Adults age 55 and older

OHS isn’t contagious — if you have OHS, you can’t spread it to others.

How will my eye doctor check for OHS?

To find out if you have OHS, eye doctors will start by looking for 2 things:

  • Scars in the back of the eye
  • Swelling in the retina (light-sensitive layer of tissue in the back of the eye)

If the doctor sees signs of OHS, they’ll do a dilated eye exam to confirm that you have OHS. Learn more about what to expect during a dilated eye exam.

If they find fluid, blood, or abnormal blood vessels during the dilated eye exam, your eye doctor may also do a test called fluorescein angiography. This test lets the doctor see pictures of the blood vessels in your retina.

What’s the treatment for OHS?

There are 2 effective treatment options for OHS. Both of these treatments are outpatient procedures — meaning you won’t need to spend the night at the hospital.

  • Injections. Medicines called anti-VEGF drugs can keep OHS from getting worse — and possibly even improve vision.
  • Laser surgery. Eye doctors can use lasers to keep abnormal blood vessels formed by OHS from leaking, bleeding, or growing.

If you already have serious vision loss from OHS, ask your doctor to refer you to a low vision specialist. They can help you learn how to live with your vision loss. Learn more about low vision.  

What’s the latest research on OHS?

A recent NEI-sponsored study suggests that injections may be the most effective way to treat OHS — but scientists are continuing to study OHS causes and treatments.

Last updated: November 20, 2020