Aspergillus keratitis presenting with an immune ring: a case report and literature review

To describe the clinical presentation, diagnostic challenges, and management of fungal keratitis (FK) caused by Aspergillus spp. presenting with a delayed immune-like ring infiltrate.

We report a case describing the clinical course, diagnostic workup, and treatment of a patient with FK initially misdiagnosed as herpes simplex keratitis.

A 68-year-old woman presented with a three-week history of decreased vision and ocular pain in the right eye. She had previously been treated with topical chloramphenicol 0.5%, frequent topical betamethasone, and oral acyclovir for presumed herpes simplex keratitis. Despite two weeks of treatment, the corneal findings progressed. At presentation to our center, a yellow-white stromal infiltrate with a surrounding immune-like ring in the inferonasal periphery was observed, along with stromal thinning and signs of impending perforation. Corneal scraping confirmed Aspergillus spp. Topical betamethasone was discontinued, and topical voriconazole 1% with chlorhexidine 0.2% was initiated. Cyanoacrylate glue was applied to manage stromal melting. Following antifungal therapy and withdrawal of topical corticosteroids, the condition stabilized.

Immune-like ring formation may be observed in FK due to immune-mediated mechanisms. Despite this immune component, topical corticosteroids should not be used empirically, as they may exacerbate fungal infection and worsen clinical outcomes. It is essential to perform corneal sampling and microbiological confirmation before initiating steroids in cases of immune-like ring lesions. This helps rule out infectious causes, especially FK.