Researchers conducted this study to report the clinical manifestations, ultrastructure, and evaluate the efficacy of therapeutic lamellar keratectomy (TLK) and penetrating keratoplasty (PK) for microsporidia stromal keratitis (MSK).

Fourteen MSK cases were recruited. The corneal manifestations were highly variable. Corneal scrapings revealed Gram stain positivity in 12 cases and modified Ziehl-Neelsen stain positivity in 9. Histopathology revealed spores in all specimens, while sequencing of small-subunit rRNA-based PCR products identified Vittaforma corneae in 82% of patients. EM demonstrated various forms of microsporidia sporoplasm in corneal keratocytes. All patients were treated with topical antimicrobial agents or combined with oral antiparasitic medications for >3 weeks. As all patients were refractory to medical therapy, they ultimately underwent surgical intervention. Postoperatively, the infection was resolved in 78.6% of the patients. Nevertheless, a high recurrence rate was noted during a 3-year follow-up, with only two patients retained a final visual acuity ≥20/100.

This study concluded that MSK usually presents with a non-specific corneal infiltration refractory to antimicrobial therapy. The diagnosis relies on light microscopic examinations on corneal scrapings and histopathological analyses. Surgical intervention is warranted by limiting the infection; however, it was associated with an overall poor outcome.