While histoplasmosis begins as a fungal lung infection, it can also affect your eyes and is a leading cause of vision loss for adults. Prevention is key before the damage progresses and can’t be treated.

Histoplasmosis is an infection caused by a type of fungus that exists in the soil, especially soil that contains bird or bat droppings. While the primary infection mostly affects the lungs, it can also result in long-term complications that affect your vision.

Histoplasmosis of the eye is also known as “presumed ocular histoplasmosis syndrome (POHS).” People might not even know they’ve had this infection, which is a leading cause of vision loss for adults.

This article will explore how you develop histoplasmosis, the effects on your eyes, and what specific eye problems you may develop as a result.

Histoplasmosis is an infection caused by breathing in microscopic Histoplasma capsulatum fungal particles. This fungus is found throughout the environment, especially in soil that’s affected by the feces of bats and some types of birds.

If you breathe in H. capsulatum particles, a lung infection will develop first. The infection can then travel through your bloodstream and eventually infect your eyes.

Many people who develop these infections aren’t even aware of the infection in its early stages.

Histoplasmosis lung infections may not cause any symptoms, or the infection can improve quickly without medical treatment. People who get sick when the infection is in the lungs generally have symptoms that include:

  • fatigue
  • cough
  • fever
  • chills
  • headache
  • chest pain
  • body aches

Even if you aren’t aware that you’ve been infected by histoplasmosis in the past, the infection can move to your eyes.

You might not notice early symptoms, but over time POHS can cause symptoms that include:

  • blurry vision
  • distorted vision that makes straight lines look wavy, bent, or crooked
  • blank spots in your central vision
  • an object may appear as a different size through each eye

The fungus that causes a histoplasmosis infection can be found in soil, but it’s most common in particular locations. H. capsulatum can be found globally in parts of Central and South America, Africa, Asia, and Australia.

In the United States, histoplasmosis infections are most common in the central and eastern states, particularly in the Ohio and Mississippi river valleys.

Disturbing the soil can release these fungal particles, so infections often develop during activities such as:

  • farming
  • chopping wood
  • digging into contaminated soil
  • cleaning chicken coops

Anyone can develop a histoplasmosis infection, but they usually don’t even know it. Our bodies are able to heal the infection, so you may think you just had a cold.

People most at risk of severe infections and complications such as POHS are those who are in repeated close contact with unclean soil or people who have weakened immune systems. You might also be at higher risk from cigarette smoking and advanced age.

Histoplasmosis infections are actually very common in areas prone to affected soil.

The Centers for Disease Control and Prevention (CDC) estimates that hundreds of thousands of people living in high risk areas may have had histoplasmosis infections without even knowing it.

Some studies have suggested that about 13 out of every 100,000 people with private insurance have had histoplasmosis, and roughly 1 in 4 people with POHS develop a severe complication called “choroidal neovascularization.”

POHS and retinopathy aren’t exactly the same, but these terms may be used interchangeably in reference to your POHS.

Retinopathy is a general term meaning “unhealthy retina,” and there are many forms of retinopathy.

Typically, an eye doctor will look for things called “histo spots” when making a diagnosis of POHS. These spots are caused by scars the infection leaves in the back area of your eye.

Another way to diagnose POHS is to examine retinal circulation in the eye. Bleeding and fluid leakage inside the retina can happen with POHS, especially when POHS leads to a condition called “choroidal neovascularization.” The choroid is a richly vascularized tissue layer beneath the retina.

With choroidal neovascularization, new blood vessels form where they don’t belong. Retinal swelling is an early indicator of this problem, and it can lead to vision loss and other issues common in people with retinopathy.

If your ocular histoplasmosis infection progresses to the point of vision loss, then it could be considered a disability.

Low vision and blindness are both considered disabilities, but whether your vision loss qualifies as a disability may depend on how much vision you’ve lost.

The Social Security Administration considers people who can’t correct their vision beyond 20/200 in the better-seeing eye to be legally blind.

When a histoplasmosis infection travels to your eye, it can cause tiny scars. These scars are deep in the eye and can usually only be seen with special examination tools used by an eye doctor. Scars left by a histoplasmosis infection are usually called “histo spots.”

There are two main treatments for histoplasmosis of the eye: injections and photocoagulation.

  • Injections: Medications called “antivascular endothelial growth factor (anti-VEGF)” drugs are often used to treat ocular histoplasmosis. Anti-VEGF drugs are also used to treat other eye conditions that affect the retina specifically, such as macular degeneration. These medications are injected into the eye, often without any pain because the eye is numbed before the medication is injected. Injected steroids are also sometimes used to treat POHS.
  • Lasers: This type of treatment, also called “laser photocoagulation,” are used to destroy the abnormal blood vessels that can form with ocular histoplasmosis. Photocoagulation is an outpatient treatment that won’t cure ocular histoplasmosis, but it may help to reduce problems caused by choroidal neovascularization. Laser treatments may be repeated if or when new blood vessels form.

Given that the damage to your eye can’t be cured or reversed once it occurs, prevention is the best tool for histoplasmosis in the eye.

Preventing histoplasmosis of the eyes

People who are at a high risk of developing histoplasmosis may take steps to reduce their risk of infection including:

  • avoiding areas of known contamination
  • using masks or other protection to prevent breathing in fungal particles
  • wetting potentially contaminated soil before digging
  • leaving areas heavily soiled with bat or bird droppings to be cleaned by hazardous material specialists
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Histoplasmosis of the eyes is a common infection that happens more than people realize. The lung infections that precede POHS can be mistaken for a simple cold, and early eye problems can go unnoticed.

Once you’re infected with histoplasmosis, the infection can move to your eyes. Most people have no visual symptoms, but merely small scars in the peripheral retina. Without prompt and effective treatment, POHS could result in vision loss and even blindness.