Effect of Previous Crosslinking on Intraoperative and Postoperative Outcomes and Complication Rates of Big-Bubble Deep Anterior Lamellar Keratoplasty for Keratoconus: A Comparative Study.

PURPOSE:To compare surgical outcomes and intraoperative and postoperative complications of big-bubble deep anterior lamellar keratoplasty (DALK) in patients with and without a history of previous corneal collagen crosslinking (CXL) for keratoconus. METHODS:Patients with keratoconus who underwent DALK surgery with big-bubble technique between January 2013 and January 2018 were retrospectively reviewed. Operative findings, intraoperative and postoperative complications, and visual and refractive outcomes were recorded. Patients were divided into 2 groups: with previous CXL (CXL-DALK group: 27 eyes) and without previous CXL (DALK group: 50 eyes). All parameters were compared between groups. RESULTS:Big bubble was successfully achieved in 24 eyes (88.9%) in the CXL-DALK group and in 45 eyes (90.0%) in the DALK group (P = 0.87). Type 1 bubble was obtained in 22 eyes (91.7%) in the CXL-DALK group and in 42 eyes (93.3%) in the DALK group (P = 0.79). Intraoperative microperforation occurred in 3 eyes (11.1%) in the CXL-DALK group and in 5 eyes (10.0%) in the DALK group (P = 1). Visual and refractive outcomes were similar between groups. The mean endothelial cell loss rates were 5.7% ± 2.3 at 1 year and 10.2 ± 3.1 at 2 years in the CXL-DALK group and 6.4% ± 4.7 at 1 year and 10.9% ± 5.4 at 2 years in the DALK group. Postoperatively, persistent epithelial defect was the most common complication in both groups, and postoperative complication rates were similar between groups. CONCLUSIONS:Our results have shown that previous CXL treatment does not influence the success of bubble formation and does not increase intraoperative or postoperative complication rates of DALK surgery for keratoconus. The improvement in visual acuity and refractive errors and endothelial cell loss rates were similar between CXL treated and untreated eyes after 2 years of follow-up.