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
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
A, Slitlamp photograph of the
right eye, with a history of progressive loss of vision for the past 6 months.
The nasal conjunctiva is swollen and shows an increased redness. The cornea
is clear with only a few endothelial precipitates. The visual acuity is hand
motions OD because of a cataractous lens and complete retinal detachment.
B, Ultrasonographic B-scan of the right eye. A complete retinal detachment
is present (arrows), and there is an anterior serous detachment of the choroid
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
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).
A, Light microscopy of the protozoan
revealed by examination of the vitreous aspirate. According to its morphologic
characteristics, this protozoan is from the Nosema genus (hematoxylin-eosin,
original magnification ×250). B, Fluorescent stain with Uvitex 2B of
a slide from the diagnostic vitrectomy. The slide was examined under a UV
microscope at a wavelength of 395 to 415 nm. The bright white spots represent
the chitin in the spore walls of the microsporidia (fluorescence, originalmagnification times250).
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: firstname.lastname@example.org).
PA Encephalitozoonosis (nosematosis) of the cornea. Br J Ophthalmol.
1973;57669- 674Google ScholarCrossref
FC Nosematosis of the cornea: case report, including electron microscopic
studies. Arch Ophthalmol.
1981;991044- 1047Google ScholarCrossref
JD Corneal microsporidiosis: report of case, including electron microscopic
2000;1071769- 1775Google ScholarCrossref
JA Corneal microsporidiosis: a case report including ultrastructural observations. Ophthalmology.
1990;97953- 957Google ScholarCrossref