Microsporidia-Induced Sclerouveitis With Retinal Detachment

Microsporidia are a rare but increasingly important group of protozoa that cause infections in vertebrates and invertebrates. Ocular involvement affecting mostly the cornea and conjunctiva in otherwise healthy patients has only occasionally been described.^1-4 To the best of our knowledge, posterior segment involvement has not been described to date. We report a case of microsporidia-induced sclerouveitis with retinal detachment.

A 66-year-old woman with a 6-year history of psoriasis had a progressive loss of vision in her right eye during the previous 6 months. Her visual acuity was hand motions OD. The conjunctiva showed moderate chemosis and increased redness (Figure 1A). The cornea was clear with a moderate amount of pigmented endothelial precipitates inferiorly. The anterior chamber was shallow, with trace cells and flare. The pupil was round and miotic with a reduced response to bright light. The lens had a dense cataract that prevented visualization of the posterior segment of the eye. Measurement with applanation tonometry was 30 mm Hg. An ultrasonographic B-scan examination showed a superior serous choroidal detachment and complete retinal detachment without funnel formation (Figure 1B).

A diagnostic vitrectomy was performed, and the lens with cataract was removed. On examination of the posterior segment of the eye, a complete serous retinal detachment was noted. The diagnosis of infection with microsporidia was made 3 days following surgery, and the patient was prescribed a systemic medication with albendazole at a dose of 400 mg twice a day. Eight months following the initial surgery, the eye was completely quiet; the silicone oil was removed, and an anterior chamber lens was implanted. Four months later the eye was still quiet, and the patient's best-corrected visual acuity was 20/200 OD.

Examinations of the vitreous aspirate included detection of the level of antibodies in both the vitreous humor and serum against varicella-zoster virus, herpes simplex virus, cytomegalovirus, and toxoplasmosis. In all instances, the antibody levels of the serum and vitreous were similar, so an intraocular synthesis of antibodies was ruled out.

Examination of the slides stained with hematoxylin-eosin and periodic acid–Schiff revealed erythrocytes, a few lymphocytes, and neutrophilic cells. A few lytic cells and free-melanin pigment granules were observed. No abnormal lymphocytes were present, and no bacteria or fungi were seen. One slide contained several spores that had features consistent with microsporidia (Figure 2A). The positive results of staining with Uvitex 2B further confirmed the diagnosis (Figure 2B).

To date, 4 cases of stromal keratitis have been reported, all of which occurred in immunocompetent patients.^1-4 The genera found include Encephalitozoon¹ and Nosema.^2-4 The number of reports of keratoconjunctivitis are increasing and generally relate to patients who are immunoincompetent, most of whom have acquired immunodeficiency syndrome. Specific microsporidia identified in these cases include Encephalitozoon hellum, Trachipleistophora species, Microsporidium ceylonensis, Microsporidium africanum, Encephalitozoon intestinalis, and Encephalitozoon cuniculi.

To our knowledge, this is the first report of severe sclerouveitis with retinal detachment caused by microsporidia. It is interesting that no such cases have previously been reported. One may speculate that thorough cytopathologic examinations of vitreous aspirates are infrequently performed in cases of uveitis of unknown origin. Fluorescent staining with Uvitex 2B clearly showed that the responsible organism in this case was a microsporidium.

Physicians confronted with a case of uveitis of unknown origin should include the possibility of microsporidia in their differential diagnosis.

Corresponding author: Holger Mietz, MD, Department of Ophthalmology, University of Cologne, 50924 Koeln, Germany (e-mail: h.mietz@uni-koeln.de).