Anterior segment optical coherence tomography of microsporidial keratoconjunctivitis.

A 17-year-old male patient presented with irritation and redness in the right eye of 1-week duration. He gave a history of rainwater entering the right eye on the day of the onset of symptoms. Corneal examination of the right eye revealed multiple, whitish, coarse punctate corneal epithelial lesions of variable sizes [Fig. 1]. Anterior segment optical coherence tomography (AS-OCT) showed intense hyper-reflective epithelial lesions raised above the surface of the epithelium [Fig. 2a]. Corneal scraping revealed microsporidia. He was started on 0.5% moxifloxacin eye drops one drop six times a day along with lubricating drops and lubricating gel at bedtime. Following treatment, the epithelial lesions resolved. One week after corneal scraping large subepithelial nummular lesions were seen [Fig. 2b]. The subepithelial nummular lesions when first seen were larger compared to adenoviral subepithelial lesions [Fig. 2c]. These lesions faded over weeks.

Figure 1

Slit lamp biomicroscope showing multiple, whitish, coarse punctate epithelial lesions of variable sizes at presentation

Figure 2

(a) Anterior segment optical coherence tomography presentation showing multiple hyper-reflective epithelial lesions of microsporidial keratoconjuctivitis which are raised above the epithelial surface. (b) Anterior segment optical coherence tomography of same patient 1 week after treated showing large sub-epithelial nummular lesions. (c) Anterior segment optical coherence tomography of adenoviral (diagnosed clinically) showing smaller nummular lesions which are seen as sub-epithelial hyper-reflective lesions. Note the smooth epithelial surface

Discussion

Keratoconjunctivitis is the most common clinical manifestation of ocular microsporidiosis.[1] The typical corneal presentation in the form of multiple, whitish, raised, epithelial lesions which are varying in size.[23] On AS-OCT, infiltration is seen as hyperreflective area.[4] The epithelial lesions in microsporidial keratoconjuctivitis can be of different types. (a) Smaller, faint white dots or round lesions. (b) Dense white, round to oval lesions. (c) Bizarre shape (pleomorphic lesions, varying in size and usually larger than the round-to-oval typed. (d). A target-like lesions with a transparent hollow center.[3] On mild debridement or swabbing, the denser white lesions are removed leaving a punched out epithelial defect. The smaller lesions which are not removed become larger and prominent on follow-up. Following treatment, the epithelial pattern evolves into a nummular pattern before resolution without scarring. Corneal edema and fine keratic precipitates may also occur.[5]

Conclusion

AS-OCT is a noncontact and noninvasive imaging technique that captures high-resolution cross-sectional images of the anterior segment. On AS-OCT, the raised hyper-reflective epithelial lesions of microsporidial keratoconjunctivitis can be differentiated from adenoviral nummular scars which are subepithelial lesions, seen as less intense hyperreflective lesions with the smooth epithelial surface. The subepithelial nummular lesions of microsporidial keratoconjunctivitis seen are larger compared to adenoviral subepithelial lesions when it first appears.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.