Presumed ocular histoplasmosis syndrome

Presumed Ocular Histoplasmosis Syndrome (POHS) is a rare eye disease that is believed to be caused by the Histoplasma capsulatum fungus. This condition is characterized by the presence of chorioretinal scars, peripapillary atrophy, and choroidal neovascularization in the absence of systemic histoplasmosis or evidence of other causes of similar ocular findings.

Etiology

The exact cause of POHS is not well understood. It is presumed to be caused by the Histoplasma capsulatum fungus, which is endemic in certain parts of the United States, particularly the Ohio River Valley and the Mississippi River Valley. However, not all individuals exposed to the fungus develop POHS, suggesting that other factors, possibly genetic, may also play a role.

Clinical Presentation

Patients with POHS typically present with symptoms of blurred vision, scotoma (blind spot), and sometimes metamorphopsia (distorted vision). On ophthalmic examination, characteristic findings include small, round, punched-out chorioretinal scars known as "histo spots," peripapillary atrophy, and choroidal neovascularization.

Diagnosis

The diagnosis of POHS is primarily clinical, based on the characteristic ocular findings in the absence of systemic histoplasmosis or other causes of similar ocular findings. Fluorescein angiography and optical coherence tomography (OCT) may be used to confirm the diagnosis and assess the extent of choroidal neovascularization.

Treatment

The primary treatment for POHS is aimed at controlling the choroidal neovascularization, which can lead to severe vision loss if left untreated. This is typically achieved with intravitreal injections of anti-vascular endothelial growth factor (anti-VEGF) agents. Laser photocoagulation may also be used in some cases.

Prognosis

The prognosis for POHS varies depending on the extent of choroidal neovascularization and the response to treatment. With early detection and treatment, vision loss can often be prevented or minimized.

See Also

• Histoplasmosis
• Choroidal neovascularization
• Ocular diseases

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