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Diagnosis Synopsis
Fungal keratitis due to Fusarium species was reported in clusters of patients in Asia in early 2006. Soon thereafter, new cases were reported to the CDC by an ophthalmologist in New Jersey. Subsequent epidemiologic investigation by the CDC has resulted in increasing reports from multiple states during the spring of 2006. The initial investigation suggests that the eye fungus is related to contact lens use, and possibly from exposure to ReNu® with MoistureLoc® contact lens solution (permanently removed from worldwide distribution on 5-15-2006) or its generic equivalent.
Fusarium keratitis is a serious, corneal stromal infection of the filamentous, non-pigmented Fusarium species. Infection with Fusarium solani, one of the more than 20 known species of Fusarium, is usually the most virulent Fusarium infection. If untreated, Fusarium keratitis can result in permanent corneal scarring and injury. The number of cases of fungal keratitis, including cases of Fusarium keratitis, has been rising during the past few decades.
Prior use of immunosuppressive agents, trauma, and recent ophthalmologic surgery are known risk factors for fungal keratitis. Contact lens use was an infrequent risk factor until the recent case reports. Prior to the 2006 reports most cases of Fusarium keratitis were seen in the southeast US or in warmer climates. In the northeast, most cases of fungal keratitis were due to Aspergillus species.
Symptoms of Fusarium keratitis include eye pain, foreign body sensation, redness, tearing, discharge, or light sensitivity.
Look For
Fungal keratitis in general causes single or multiple corneal infiltrates with gray-white feathery edges and may have associated satellite lesions. There may be underlying corneal edema and/or an anterior chamber reaction. Advanced cases may demonstrate a hypopyon, a layering of white blood cells in the inferior anterior chamber angle.
Diagnostic Pearls
Often the onset of symptoms is not acute but rather over several days and even weeks. There is often a history of trauma with vegetable matter.
Differential Diagnosis & Pitfalls
Bacterial keratitis usually has a more acute onset of symptoms and typically does not have feathery edges or "satellite" lesions.
Herpes simplex keratitis often has a history of previous episodes. It may have a classic dendritic epithelial lesion (treebranch pattern) and symptoms almost always occur in just one eye.
Interstitial keratitis is uncommon and presents with prominent corneal vascularization.
Best Tests
Corneal scrapings for smears and cultures are the best first step in making the diagnosis. Smears should be stained for fungal material (e.g. Giemsa, PAS, GMS, calcofluor white). Culture material should include Sabouraud's medium for fungus, in addition to standard bacterial cultures (blood and chocolate agar and thioglycolate liquid). A corneal biopsy may be required when scrapings are unrevealing.
Management Pearls
Generally antifungal medications are not used unless fungus is found on smears or cultures. Repeat scrapings may be required if the eye is not improving clinically. A corneal biopsy should be considered when scrapings are negative and the infiltrate is not improving. If Fusarium is suspected, an ophthalmology consult should be sought.
Therapy
The standard treatment of Fusarium fungal keratitis is frequent use of Natamycin 5% drops, often used every hour around the clock initially. A cycloplegic drop, e.g., scopolamine 0.25%, is also usually used to decrease the inflammation inside the eye. Occasionally, oral antifungal medications, e.g., itraconazole, fluconazole or voriconazole are also used. An urgent corneal transplant may be required in deep infections with impending or frank perforations.
Medical Disclaimer:
The information contained in this web page is intended to be an adjunct to traditional medical information sources. It is not intended to be a substitute for professional medical judgment.
Author:
Christopher J. Rapuano, MD
Co-Director and Attending Surgeon, Cornea Service Co-Director, Refractive Surgery Department, Wills Eye Hospital
Professor, Jefferson Medical College of Thomas Jefferson University Philadelphia, PA
References:
The Wills Eye Manual, 4th edition
Kunimoto, Kanitkar, Makar, eds, Lippincott, Williams & Williams
2004.
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Fusarium Keratitis Info
