Diagnosis of microsporidial keratitis with in vivo confocal microscopy

Issue title: Recent Advances in Clinical Diagnosis and Therapeutics

Article type: Research Article

Authors: Hsiao, Ya-Chuan^; | Tsai, I-Lun | Kuo, Chin-Tzu | Yang, Tsung-Lin^;

Affiliations: Department of Ophthalmology, Zhongxing Branch, Taipei City Hospital, Taipei, Taiwan | Department of Ophthalmology, College of Medicine, National Yang-Ming University, Taipei, Taiwan | Department of Otolaryngology, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan | Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, Taiwan

Note: [] Corresponding author: Tsung-Lin Yang, Department of Otolaryngology, National Taiwan University Hospital, #1, Sec. 1 Jen-Ai Road, Taipei 100, Taiwan. Tel.: +886 2 2312 3456, ext 63526; Fax: +886 2 2341 0905; E-mail: [email protected]

Abstract: As a rare cause of microbial keratitis, microsporidial keratitis (MK) is first described in a patient with acquired immunodeficiency syndrome. As increased use of topical steroid creates a localized immunosuppressive environment of the eyes, MK occurs more commonly than expected in immunocompetent patients nowadays. Owing to initial insidious growth of pathogens and nonspecific ocular symptoms of infected patients, its frequent misdiagnosis has posed a major clinical challenge in recent decades. Without appropriate treatments, MK can progress deeply into corneal stroma, anterior and posterior segments, subsequently deteriorating vision severely and ultimately requiring corneal transplant. Related risk factors for the occurrence of MK in immunocompetent individuals include contact lens wear, topical steroid use, previous corneal trauma, and a history of laser refractive surgery. The conventional standard of MK diagnosis is based on a tissue biopsy by superficial corneal scrapping. In vivo confocal laser scanning microscopy can obtain images through the cornea in a plane paralleling to the vertical axis. This approach provides an effective method of identifying tissue layers that correspond to corneal histologic structures. This current study investigates the efficacy of \textit{in vivo} confocal laser scanning microscopy in diagnosing MK in immunocompetent patients. The clinical presentations of enrolled patients, including features of slit lamp biomicroscopy and the histopathological results of corneal scrapping, were described. In these patients, the confocal microscopy identified multiple small intracellular hyper-reflective dots in the cytoplasm of corneal epithelial cells and stromal keratocytes. Additionally, the confocal microscopic images clearly revealed the enhanced cytoplasm of cell with intracellular round hyper-reflective dots. The size and morphology of hyper-reflective dots were compatible with the spores of microsporidia found in corneal tissue. Moreover, vision recovered after topical use of antimicrobial medicine. This observation suggests that in vivo confocal laser scanning microscopy provides a rapid, non-invasive, and high resolution scheme for diagnosing MK. In addition to diminishing the risk of secondary infection from epithelial defect created by superficial debridement, this approach facilitates early diagnosis and appropriate treatments. Furthermore, from a series of images taken during the clinical courses, this method is highly promising for use in monitoring treatment effects and identifying the recurrence of MK.

Keywords: Microsporidial keratitis, confocal microscopy, microsporidial keratoconjunctivitis, corneal scrapping

Journal: Journal of X-Ray Science and Technology, vol. 21, no. 1, pp. 103-110, 2013