Presumed Ocular Histoplasmosis Syndrome Clinical Presentation

Updated: Sep 20, 2018
  • Author: Lihteh Wu, MD; Chief Editor: C Stephen Foster, MD, FACS, FACR, FAAO, FARVO  more...
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Presentation

History

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  • Residents or visitors to endemic areas

  • Prior exposure to chickens, parakeets, or pigeons

  • Distorted vision

  • Sudden, painless loss of central visual acuity

  • Micropsia

  • Positive scotoma

  • Asymptomatic

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Physical

Both the vitreous and the anterior chamber are typically clear because of a lack of intraocular inflammation.

Punched-out chorioretinal scars (smaller in size than the optic nerve) are called histo spots. Black pigment may appear within or at the margins of these lesions. Linear streaks of atrophic scars in the mid periphery are observed in about 5% of patients with POHS.

Peripapillary chorioretinal scarring is present.

Macular CNV usually is observed as a gray-green subretinal lesion that is surrounded by subretinal blood and leads to a serous or hemorrhagic macular detachment. CNV is estimated to occur in 5% of eyes affected with POHS.

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Causes

The cause of presumed ocular histoplasmosis syndrome is H capsulatum.

Smoking

In a retrospective case control study, 142 eyes with choroidal neovascularization secondary to ocular histoplasmosis were compared to a similar cohort of 426 patients without ocular histoplasmosis. The likelihood of a smoker developing choroidal neovascularization was almost 3 times higher than a nonsmoking person. [20]

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