Eye condition known as Presumed Ocular Histoplasmosis Syndrome (POHS): Symptoms and remedies for treatment

Eye condition known as Presumed Ocular Histoplasmosis Syndrome (POHS): Symptoms and remedies for treatment

News Article: Understanding Presumed Ocular Histoplasmosis Syndrome (POHS)

Presumed Ocular Histoplasmosis Syndrome (POHS) is a lesser-known eye disorder that has been linked to a fungal infection caused by Histoplasma capsulatum. While experts continue to study the connection between the two, it remains unclear why some people with histoplasmosis exposure develop POHS and others do not.

POHS is characterized by distinctive retinal scars and choroidal neovascularization, which can lead to progressive vision loss if left untreated. The syndrome typically presents without active inflammation but can cause significant visual impairment, particularly from complications like choroidal neovascular membranes.

Impact on vision loss from POHS occurs mainly because the abnormal blood vessels that grow beneath the retina can leak or bleed, damaging the macula (the central part of the retina responsible for sharp vision) and causing vision distortion or blindness if untreated. Early diagnosis through fundoscopy and imaging, followed by monitoring and timely treatment, are key to preserving vision.

POHS is more common in areas where histoplasmosis is common, such as the Ohio and Mississippi River valleys, where as many as 60% of adults test positive on a skin test. The leading theory for explaining POHS is that it begins when people inhale spores from the fungus Histoplasma capsulatum.

While direct evidence of active fungal infection in ocular tissues is rare, current research suggests that the disease mechanism may involve immune-mediated responses triggered by past infection rather than ongoing fungal presence. This understanding affects treatment approaches, which focus on managing complications rather than antifungal therapy.

Treatment for POHS focuses on reducing inflammation and damage to the eyes, often through the use of injectable drugs such as bevacizumab (Avastin), ranibizumab (Lucentis), and aflibercept (Eylea). Early intervention is crucial for many eye health issues, including POHS, as the outlook is best with early treatment.

Certain risk factors for developing POHS include having a weakened immune system (e.g., living with HIV or AIDS), being 55 or older, smoking, and having a preexisting lung condition. POHS does not usually cause pain.

Diagnosis for POHS involves a doctor examining the eyes, dilating the pupils, and potentially using imaging tests such as ocular coherence tomography (OCT) and fluorescein angiography (FA) to see the vessels at the back of the eye. Photodynamic therapy and laser surgery may also be used in the treatment of POHS.

According to the CDC, scientists do not have reliable statistics on POHS, but it likely affects hundreds of thousands of people each year. POHS can cause scarring at the back of the eye, around the retina, and the optic nerve. The link between Histoplasma and POHS is not fully proven. More research is necessary to understand how this fungus might cause POHS and its impact on vision loss.

Despite the uncertainties, the outlook for POHS is generally good with early treatment, as it can prevent harmful scarring and potentially reverse some vision loss. The importance of early detection, regular monitoring, and management of vascular complications cannot be overstated in minimizing vision loss in individuals with POHS linked to Histoplasma infection.

1. POHS, a lesser-known eye disorder linked to Histoplasma capsulatum, can lead to vision loss if left untreated, primarily due to abnormal blood vessels beneath the retina leaking or bleeding.
2. Vital for preserving vision, early diagnosis through fundoscopy, imaging, and regular monitoring are essential in managing POHS.
3. Research suggests that POHS may involve immune-mediated responses triggered by past infections, affecting the treatment approach as it focuses on managing complications rather than antifungal therapy.
4. Treatment for POHS often involves injectable drugs, such as bevacizumab, ranibizumab, and aflibercept, aimed at reducing inflammation and damage to the eyes.
5. Although the link between Histoplasma and POHS is not fully understood, the Centers for Disease Control and Prevention (CDC) estimates that POHS likely affects hundreds of thousands of people each year, causing scarring at the back of the eye, around the retina, and the optic nerve.

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