Presumed Ocular Histoplasmosis Syndrome (POHS) is a serious condition that affects your vision by causing abnormalities in the retina. Our specialized retina experts are here to help you manage and treat this condition effectively.
This page provides detailed information on Presumed Ocular Histoplasmosis Syndrome (POHS), covering its overview, causes, diagnosis, treatment options, long-term management, and essential guidance for maintaining vision.
Presumed Ocular Histoplasmosis Syndrome (POHS) affects the retina, the part of your eye that senses light, and can impact your vision. It's caused by earlier exposure to a common soil fungus, Histoplasma capsulatum, often found in places like the Ohio and Mississippi River valleys. Catching POHS early matters. Many people don't notice symptoms, but regular monitoring can help prevent vision loss if abnormal blood vessels start to grow.
POHS is a condition where tiny scars called histo spots form on the retina after earlier exposure to the Histoplasma fungus. These scars are thought to result from the body’s immune response after breathing in fungal spores. Most people exposed to the fungus don’t have any eye problems. But in some cases, the scars can lead to abnormal blood vessel growth in the retina, called choroidal neovascularization (CNV), which can cause vision issues.
Presumed Ocular Histoplasmosis Syndrome (POHS) often develops without clear symptoms at first, making it hard to catch without a detailed eye exam. Early on, your retina can look completely normal, even during routine checkups. But underneath, past exposure to the Histoplasma fungus can slowly cause changes. Over time, this may lead to the growth of abnormal blood vessels near the macula, the part of the eye responsible for sharp, central vision. These vessels can leak fluid or blood, harming your vision and possibly causing lasting damage if not treated.
When POHS leads to complications, certain changes in your vision may appear. These signs can show up slowly or suddenly, and even small shifts are worth taking seriously. If you notice any of the following, it’s important to contact our retina specialist:
The exact pathway that leads from exposure to Histoplasma capsulatum to POHS is still being researched. However, experts believe that the process begins when you inhale fungal spores, usually in regions where the fungus thrives in soil enriched with bird or bat droppings. For most people, this exposure results in a mild or unnoticed lung infection, but in some cases, the fungus appears to trigger small scars in the retina later on.
These retinal scars or “histo spots” do not cause problems by themselves but can later foster the development of abnormal blood vessels around the retina. This growth, termed choroidal neovascularization, disrupts the normal structure and function of the retina, leading to potential vision loss if left untreated.
Although many people are exposed to Histoplasma capsulatum at some point in life, only a handful develop POHS. Factors that may increase one’s risk include:
Regular comprehensive eye exams are key to spotting Presumed Ocular Histoplasmosis Syndrome (POHS) early, often before you notice any symptoms. Our retina specialists use a thorough, step-by-step approach to detect signs like histo spots, abnormal blood vessel growth (choroidal neovascularization), and other subtle changes in the retina.
If you're concerned about your vision or have risk factors for Presumed Ocular Histoplasmosis Syndrome, reach out to our specialized retina teams today. Our experts provide personalized care to help you maintain your eyesight. Find a top optometrist or ophthalmologist near you through Specialty Vision.
Anti-VEGF therapy is the most effective treatment for vision loss caused by Presumed Ocular Histoplasmosis Syndrome (POHS). It targets VEGF, a protein that drives abnormal blood vessel growth beneath the retina. By blocking VEGF, these injections help stop leakage, limit further damage, and can stabilize or even improve vision, especially when started early.
Treatment usually begins with monthly injections, with your response closely monitored by our retina specialists. Follow-up visits are essential to track progress and adjust care as needed.
What to expect during treatment:
Before anti-VEGF became the preferred method, laser photocoagulation was commonly used. This treatment seals leaking blood vessels with a focused laser, helping to prevent further fluid buildup in the retina. Because it can create permanent blind spots, laser therapy is now mostly used when the abnormal vessels don’t involve the macula’s center. Our team evaluates each case to determine if it’s the right option.
Photodynamic therapy is sometimes used as an alternative or add-on treatment. It starts with an injection of a light-sensitive drug that gathers in the abnormal blood vessels. We then apply a low-energy laser to activate the drug, which causes the vessels to close off without harming nearby tissue. Though used less often today, PDT can be helpful in cases where anti-VEGF treatment alone isn't enough.
Even if you are not presently experiencing symptoms, regular monitoring is essential when you have a history of histoplasmosis or other risk factors associated with POHS. Our retina specialists emphasize the importance of keeping a close watch on your vision, as changes can occur suddenly.
While the prospect of POHS can be concerning, it is important to remember that many individuals maintain good vision with early detection and appropriate treatment. Understanding your condition and being proactive in scheduling regular eye exams can help you feel more in control of your eye health. The commitment of our retina specialists is to work with you every step of the way, ensuring that you receive personalized care tailored to your needs.
Your treatment plan is designed to minimize vision loss and maintain the quality of your sight, offering hope and improved outcomes even when facing complications from this condition.
Since POHS requires lifelong monitoring, staying informed and vigilant about your eye health is essential. It is reassuring to know that modern treatments and refined diagnostic tools have significantly improved how we manage this condition, allowing many patients to enjoy a good quality of vision over the long term.
No, POHS is not an active infection. It is a condition that results from a past exposure to Histoplasma capsulatum. The fungus itself is not actively infecting the eye; instead, it is the scarring from the previous exposure that may eventually lead to complications in vision.
In most cases, exposure to Histoplasma capsulatum does not result in POHS. Many people inhale the fungal spores during their lifetime without ever experiencing symptoms or changes in their eye health. POHS tends to develop only in a small percentage of individuals who have a certain predisposition or additional risk factors.
Vision changes related to POHS can occur either gradually or suddenly, particularly if choroidal neovascularization develops. While many patients do not notice any changes initially, any sudden appearance of blurred or distorted vision should be addressed immediately by our retina specialists for a thorough evaluation.
Since Histoplasma capsulatum is present in the environment, it is difficult to avoid exposure completely. However, if you know that you are at risk, especially if you live in high-prevalence areas, it is important to be mindful of activities that may stir up contaminated soil, such as working near chicken coops or in areas with bat droppings. Regular eye examinations are the best way to catch any early signs of POHS before they affect your vision.
If you're concerned about your vision or have risk factors for Presumed Ocular Histoplasmosis Syndrome, reach out to our specialized retina teams today. Our experts provide personalized care to help you maintain your eyesight. Find a top optometrist or ophthalmologist near you through Specialty Vision.
Presumed Ocular Histoplasmosis Syndrome (POHS) can impact your vision. Learn about causes, symptoms, and treatment options for POHS.
