Late-Onset Infectious Keratitis Over 10 Years After Intracorneal Ring Segment Implantation Treated with Deep Anterior Lamellar Keratoplasty: A Case Report

Introduction: Intracorneal ring segments (ICRS) are employed to manage keratoconus but carry the risk of late-onset complications such as extrusion and infectious keratitis. We report a rare case of infectious keratitis occurring over 10 years following ICRS implantation that was successfully treated with deep anterior lamellar keratoplasty (DALK). Case presentation: A 56-year-old woman with atopic dermatitis and keratoconus presented with severe pain and visual loss in the left eye, where an ICRS had been implanted over 10 years ago. Examination revealed counting-finger vision, dense corneal infiltration around the ICRS, and a hypopyon. Despite intensive antibacterial therapy resolving the active infection, progressive stromal melting resulted in ICRS extrusion. Therapeutic DALK was conducted using the big-bubble method after ICRS explantation. The postoperative course was uneventful, and the graft remained clear after 12 months. Conclusions: Late-onset infectious keratitis can occur even a decade after ICRS implantation, particularly in high-risk patients such as those with atopic dermatitis. In cases of severe stromal thinning or extrusion, DALK offers effective restoration of ocular integrity while minimizing the risk of endothelial rejection. This case highlights that lifelong vigilance is necessary following ICRS implantation, especially in atopic patients, and that DALK may be a valuable alternative to penetrating keratoplasty in advanced cases.