Presumed Ocular Histoplasmosis Syndrome (POHS) can silently affect your vision, often causing no symptoms until it's advanced. Early diagnosis and treatment by our retina specialists can help you maintain eye health and perfect vision. Find a top optometrist or ophthalmologist near you through Specialty Vision.
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) is an eye condition that impacts the retina, the light-sensitive layer at the back of your eye, and may affect your vision. It is linked to past exposure to a common soil fungus, Histoplasma capsulatum, which is found in areas like the Ohio and Mississippi River valleys. Recognizing POHS early is important because, although many people may never notice symptoms, timely monitoring can help prevent vision loss if abnormal blood vessel growth develops.
POHS is a condition where small, often silent scars known as histo spots form on the retina from previous exposure to the Histoplasma fungus. These scars are a result of what is believed to be an immune response after inhaling fungal spores; most individuals come into contact with this fungus without experiencing any eye-related issues. In some cases, however, these scars trigger the growth of abnormal blood vessels in the retina, a process called choroidal neovascularization (CNV), which can lead to vision problems.
Presumed Ocular Histoplasmosis Syndrome (POHS) typically does not present noticeable symptoms in its early stages, making it challenging to detect without professional examination. Initially, your retina might appear healthy and normal, even during routine eye exams. However, beneath the surface, the fungus Histoplasma may cause subtle, progressive changes, ultimately leading to abnormal blood vessel growth, known as choroidal neovascularization, near the macula, the sensitive area responsible for central, detailed vision. Once these vessels form, they can leak fluid or blood, significantly impacting your vision and potentially causing permanent damage if left untreated.
When complications arise due to POHS, you could notice certain visual disturbances that signal a change in your eye health. These symptoms may develop either gradually or suddenly, and even subtle changes are worth noting. If you start noticing any unusual changes in your vision, it’s best to seek guidance from our retina specialists immediately. Watch out for:
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 examinations are crucial for the early detection of Presumed Ocular Histoplasmosis Syndrome (POHS), even before symptoms become apparent. Our retina specialists employ a detailed and systematic approach to identify characteristic retinal changes associated with POHS, including histo spots, abnormal blood vessel growth (choroidal neovascularization), and other subtle retinal alterations.
A precise diagnosis involves advanced imaging technologies that allow an in-depth analysis of retinal health:
If you suspect you may be at risk for Presumed Ocular Histoplasmosis Syndrome or are experiencing vision changes, contact one of our experienced retina specialists listed with Specialty Vision today. They can provide you with a thorough examination and personalized treatment options to protect your eyesight.
Anti-VEGF (vascular endothelial growth factor) therapy is the standard and most effective treatment for vision loss caused by Presumed Ocular Histoplasmosis Syndrome (POHS). This therapy specifically targets VEGF, a protein that promotes abnormal blood vessel growth under the retina. By inhibiting VEGF, anti-VEGF injections effectively reduce vessel leakage and prevent further damage to retinal tissue, potentially stabilizing and improving vision, especially when initiated promptly.
Initially, treatment often involves monthly injections, carefully monitored and adjusted by our retina specialists based on your eye's response. Consistent follow-up visits ensure optimal outcomes.
Here's what you can expect during an anti-VEGF treatment session:
Before anti-VEGF became the preferred approach, laser photocoagulation was widely used to treat POHS. This procedure employs a laser to seal off leaking blood vessels, preventing further leakage into retinal tissues. However, due to the potential for permanent blind spots (scotomas), laser therapy is now typically reserved for cases where abnormal blood vessels do not involve the macula's central region. Our specialists carefully evaluate the appropriateness of laser therapy based on individual circumstances.
Photodynamic therapy (PDT) remains an important alternative or complementary treatment for select cases. During PDT, we intravenously administer a light-sensitive medication, which preferentially accumulates in abnormal retinal vessels. Afterward, we precisely apply a low-energy laser to activate the medication, causing selective closure of problematic blood vessels. Though less commonly used today, PDT offers significant benefits in certain scenarios, especially when anti-VEGF therapy alone may not suffice.
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 suspect you may be at risk for Presumed Ocular Histoplasmosis Syndrome or are experiencing vision changes, contact one of our experienced retina specialists listed with Specialty Vision today. They can provide you with a thorough examination and personalized treatment options to protect your eyesight.
Understand Presumed Ocular Histoplasmosis Syndrome (POHS), its symptoms, and treatment options. Find a top optometrist or ophthalmologist near you.
