In vivo confocal microscopic characteristics of microsporidial keratoconjunctivitis in immunocompetent adults

Background/aims To describe in vivo confocal microscopy (IVCM) features of microsporidial keratoconjunctivitis in immunocompetent adult patients. Methods Patients suspected clinically to be suffering from microsporidial keratoconjunctivitis (ie, presence of unilateral follicular and/or papillary conjunctivitis in conjunction with multifocal, coarse corneal epitheliopathy) were subjected to IVCM with the Rostock Cornea Module of the Heidelberg Retinal Tomograph 3, and combined potassium hydroxide and calcofluor white (KOH+CFW) staining of the corneal scrapings, to detect the microsporidial spores. Detection of spores in corneal scrapings was considered as being confirmatory for microsporidial infection. Results Of a total of 10 patients screened, 8 patients (7 male, 1 female) demonstrated the presence of oval, non-budding microsporidial spores which fluoresced bluish white on combined KOH+CFW staining. IVCM in seven of these eight patients demonstrated multiple rosette-like clusters/plaque of epithelial cells, within which hyper-reflective, pinpoint oval intracellular bodies (similar to the spores seen on microbiological staining) were present. One patient who had been on prolonged treatment with topical steroids showed the presence of the oval bright bodies scattered diffusely within the epithelial cells, without rosette formation. Conclusions In microsporidial keratoconjunctivitis, IVCM is able to detect presence of bright, ovoid spore-like structures in the epithelial layers. Epithelial rosette formation is another characteristic feature seen in a majority of these patients. These features may be used as a reliable screening tool for starting therapy, precluding the need for corneal scrapings in a majority of patients.