Wednesday, June 12, 2024
HomeOphthalmologyOcular Coccidioidomycosis

Ocular Coccidioidomycosis

Overview

Coccidioidomycosis is a disease caused by Coccidioides immitis, a dimorphic fungus that thrives in the lower Sonoran Desert ecozone of the Western hemisphere.
Coccidioidal uveitis should be considered in any patient with apparent idiopathic iritis who has lived or traveled through endemic areas, including Arizona, New Mexico, west Texas, parts of Central America, Argentina, northwest Mexico, and the San Joaquin Valley in California.

The warm, dry climate and sandy, saline soil are ideal for growth of the mycelial phase of the fungus. The mold forms hyphae of 2-4 mm, which consist of chains of arthroconidia that later germinate under moist conditions. During dry seasons, winds spread the highly infectious arthrospores and infection occurs through inhalation of contaminated dust. No documented cases of animal-to-human or human-to-human transmission have occurred.

Ocular involvement occurs secondary to dissemination and is considered rare.
The eyelids and conjunctiva are the most common sites. The skin of the eyelids may contain granulomatous foci of Langerhans giant cells and coccidioidal spherules.
Phlyctenular conjunctivitis may be seen and represents a hypersensitivity reaction.
True mycotic granulomas of the conjunctiva are less common than hypersensitivity conjunctivitis and usually are seen in the presence of skin lesions.

The uvea is the most common site of intraocular disease. A granulomatous iridocyclitis with iris nodules and posterior synechiae may be seen.
However, the typical infection is a multifocal choroiditis with many discrete, yellow-white lesions less than a disc diameter in size.

Also see Coccidioidomycosis and Dermatologic Manifestations of Coccidioidomycosis.

Complications

Vitreitis, vasculitis, serous retinal detachment, and retinal haze may occur in the acute phase. Typical coccidioidal granulomas with spherules are seen in the choroid on histopathology.
Lesions also have been noted within the optic nerves. One histopathologically documented case of intraretinal granulomas and organisms that occurred in a previously healthy 12-year-old child has been reported.

Choroidal neovascularization may occur in areas of scarring. Secondary glaucoma may occur from inflammation and its sequelae. Retinal seeding from anterior disease may occur following vitrectomy.

Presenting visual acuity of patients reported in the literature ranges from 20/20 to 20/200.
Final visual acuity ranges from 20/20 to no light perception, depending on severity, time to diagnosis, and patient compliance with medical therapy and follow-up care.

RELATED ARTICLES
- Advertisment -

Most Popular