Bilateral microsporidial keratoconjunctivitis was identified in an immunocompetent pediatric patient who wore orthokeratology lenses after treatment for presumed allergic conjunctivitis failed. The case suggested that microsporidial infection may warrant consideration in patients with persistent keratoconjunctivitis that does not respond to conventional therapy.
Researchers described a 9-year-old female patient who presented with a 3-week history of bilateral eye redness, itching, discomfort, and episodic foreign-body sensation. She had initially been diagnosed with bilateral allergic conjunctivitis at another hospital and received antiallergic eye drops without improvement. The patient had a history of prolonged orthokeratology lens wear and recent household exposure to pet parrots but denied cleaning her lenses with tap water. Her sister, who shared the household but did not wear orthokeratology lenses, had no ocular symptoms.
At presentation, best-corrected visual acuity was 20/25 in both eyes. Slit-lamp examination showed bilateral conjunctival congestion, papillary and follicular changes, and scattered grayish-white epithelial and subepithelial punctate corneal infiltrates. In vivo confocal microscopy (IVCM) demonstrated epithelial edema, Langerhans cell infiltration, and punctate hyperreflective signals, while anterior segment optical coherence tomography (AS-OCT) showed an irregular corneal epithelial surface with elevated punctate hyperreflective signals.
Researchers obtained a superficial corneal scraping and performed metagenomic next-generation sequencing (mNGS). The analysis identified E hellem, with 16.14% genome coverage, supporting the diagnosis of microsporidial keratoconjunctivitis. Smear and staining for microbiologic evaluation could not be performed because of sampling limitations.
Following confirmation of the infection, the patient received 0.02% chlorhexidine eye drops every 2 hours initially, reduced to 4 times daily on day 14 and discontinued after 1 month. She also received levofloxacin eye drops 4 times daily and ofloxacin eye ointment once nightly. No topical or systemic corticosteroids were administered.
By day 7, ocular symptoms had improved and the area of corneal staining had decreased. By day 14, symptoms had nearly resolved, with a substantial reduction in corneal staining and no residual scarring or opacification. AS-OCT showed restoration of a smooth corneal epithelial surface, and best-corrected visual acuity improved to 20/20 in both eyes. The patient remained under follow-up without further ocular discomfort or visual decline.
The researchers identified prolonged orthokeratology lens wear and household exposure to a pet parrot as potential risk factors but could not determine the infection source. Neither the contact lens care solution and lens case nor the parrot's feces were tested. The patient's sister also remained unaffected despite sharing the same environment. The researchers therefore noted that lens wear and animal contact may both have contributed to the infection but did not establish either exposure as its cause.
Microsporidial keratoconjunctivitis may be difficult to recognize because its clinical manifestations are nonspecific and can resemble other corneal diseases. The researchers noted that AS-OCT and IVCM can provide diagnostic information but cannot directly identify microsporidia. In the reported case, mNGS enabled species-level identification of E hellem and subsequently guided targeted therapy.
The case report had several limitations. Findings from a single patient may not be generalizable to the broader population of patients who wear orthokeratology lenses. Microscopic confirmation using special staining was not performed, and the researchers did not microbiologically test potential environmental sources, leaving the contribution of the patient's parrot exposure and lens wear uncertain. Long-term outcomes and recurrence rates also were not assessed.
The findings support considering microsporidial infection in the differential diagnosis of persistent corneal infection associated with orthokeratology lens wear, particularly when conventional treatment is unsuccessful. The researchers recommended corneal scraping or molecular testing when feasible to confirm the diagnosis and guide targeted therapy.
“This case underscores the rare occurrence of bilateral microsporidial keratoconjunctivitis in an immunocompetent child wearing orthokeratology lenses,” wrote coauthor Rongbin Liang, of the Department of Ophthalmology at Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, and colleague.
The researchers reported no funding or competing interests.
Source: BMC Ophthalmology
