Anterior Stromal Melt Following Implantation of a Large Size Corneal Allogenic Intrastromal Ring Segment (CAIRS).

PURPOSE: To report delayed anterior stromal melt following corneal allogenic intrastromal ring segment (CAIRS) implantation in a patient without known systemic or ocular risk factors.

METHODS

A 62-year-old man with advanced bilateral keratoconus underwent femtosecond laser-assisted CAIRS implantation at 260 µm depth (900 µm tunnel width). Three months postoperatively, CDVA improved from 20/150- and 20/400 to 20/80 bilaterally and Kmax improved from 59.67 and 67.56 diopters (D) to 54.39 and 64.72 D in the right and left eyes, respectively. Optical coherence tomography (OCT) measured the segment at 624 µm in the right eye.

RESULTS

Ten months postoperatively, the right eye demonstrated focal epithelial thinning with fluorescein staining and melt localized over the inferotemporal segment; overlying stromal thickness decreased from 133 µm (week 1) to 7 µm on OCT. The left eye remained unaffected. Topical loteprednol, lubrication, and systemic doxycycline were initiated. Nineteen months postoperatively, OCT and topography demonstrated stromal stability. Despite astigmatic regression, CDVA remained better than baseline, and the CAIRS was retained.

CONCLUSIONS

The large segment size placed superficially may have contributed to localized biomechanical stress, particularly in eyes with advanced keratoconus. Safe thresholds for segment/tunnel sizes, depth, and location warrant further studies.