Late-onset sterile peripheral ulcerative keratitis post-corneal collagen crosslinking

Purpose:To report the incidence, characteristics, clinical presentations, risk factors, and the available treatment modalities of sterile peripheral ulcerative keratitis (PUK) post-corneal collagen crosslinking (CXL).Methods:This study is a retrospective study including 771 eyes of 474 patients operated for keratoconus or ectasia after LASIK 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 1 year post-CXL.Results:Eleven eyes (1.4%) of 8 patients developed late-onset PUK with or without corneal haze and sterile infiltrates. The complications occurred between 3 months and 6 years postoperatively. Their mean age of 39.6 ± 7.1 years was higher than the age of the noncomplicated patients 21.9 ± 8.8 years (P = 0.0001). 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 with keratitis. Duration of ultraviolet light exposure 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.Conclusions:PUK is a rare but serious complication after CXL. Long-term follow-up is necessary to detect late-onset PUK. It is a treatable condition associated with older age and autoimmune conditions but has a good visual outcome.