Corneal microsporidiosis: Report of case, including electron microscopic observations

Ramon L. Font, Ameed N. Samaha, Mary J. Keener, Patricia Chévez-Barrios, John D. Goosey

Research output: Contribution to journalArticle

42 Scopus citations


Objective: To report a case of corneal stromal infection caused by a protozoon of the genus Microsporidia, including clinical, histopathologic, and electron microscopic observations. Design: Case report. Methods: Light and electron microscopy studies were performed on keratectomy specimens from a 67-year-old immunocompetent man who had a unilateral chronic stromal keratitis that was refractory to medical treatment. Initial corneal biopsy followed by lamellar and penetrating keratoplasty were performed on the patient. All the specimens were studied histopathologically. Results: Light microscopy of the corneal biopsy and the subsequent keratectomy specimens demonstrated myriad small, round to oval microsporidial organisms measuring 3.5 to 5.0 μm in length that stained positively with the periodic acid-Schiff, Grocott-methenamine silver, and acid-fast methods and were gram positive. Electron microscopic observations demonstrated viable blastospores that had a thin osmiophilic outer cell wall and contained 11 to 13 coils of the filament. The light and electron microscopic features, the tinctorial characteristics, and the selective corneal stromal involvement are consistent with microsporidial keratitis. Conclusions: Microsporidiosis should be considered in the differential diagnosis of a culture-negative stromal keratitis refractory to medical treatment. The diagnosis can be easily established based on the morphologic features of the protozoa in the keratectomy specimens. No effective medical treatment for the stromal disease is available. Full-thickness keratoplasty is suggested because, in our patient, lamellar keratoplasty did not preclude recurrence of the disease. (C) 2000 by the American Academy of Ophthalmology.

Original languageEnglish (US)
Pages (from-to)1769-1775
Number of pages7
Issue number9
StatePublished - Nov 22 2000

ASJC Scopus subject areas

  • Ophthalmology

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