Corneal collagen crosslinking (CXL) is a generally safe and successful way to slow the progression of keratoconus. But a small subset of patients may be at higher risk of peripheral ulcerative keratitis (PUK), a new study finds.

A retrospective study looked at 771 eyes of 474 patients operated for keratoconus or post-LASIK ectasia between January 2010 and June 2017 at Beirut Eye & ENT Specialist hospital. The average follow-up period was 4.2 years with a minimum of one year post-CXL. 

Eleven eyes (1.4%) of eight patients developed late-onset PUK with or without corneal haze and sterile infiltrates. The complications occurred between three months and six years postoperaively. Mean age for affected individuals (39.6 ±7.1 years) was higher than that of the noncomplicated patients (21.9 ±8.8 years). Four affected patients had inflammatory and autoimmune conditions.

Sex, presence of intrastromal ring segments, mean keratometry and the thinnest pachymetry were found to be insignificantly different between groups, and photorefractive keratectomy was performed more in patients who experienced keratitis. Duration of ultraviolet light exposure, however, was related to sterile ulcerative keratitis development. All patients responded to steroid treatment, and only one had a relapse, which resolved with topical cyclosporine 1% drops.

“Long-term follow-up is necessary to detect late-onset PUK,” the authors wrote in their paper. “It is a treatable condition associated with older age and autoimmune conditions but has a good visual outcome.”