Outcomes of Simultaneous and Sequential Cross-linking With Excimer Laser Surface Ablation in Keratoconus

To evaluate the outcomes of simultaneous and sequential corneal crosslinking (CXL) and excimer laser surface ablation protocols in keratoconus.

A literature review was conducted using MEDLINE. The studies were divided into three groups: the sequential group included studies with CXL followed by excimer laser surface ablation later, the simultaneous group included simultaneous excimer laser surface ablation and CXL, and the no CXL group included excimer laser surface ablation only with no CXL. The data on change in logMAR uncorrected distance visual acuity (UDVA), spectacle corrected distance visual acuity (CDVA), change in spherical equivalent (SE) and refractive astigmatism, change in maximum keratometry (Kmax), complications, and safety and efficacy indices were presented for the latest follow-up visits in all groups.

Twenty-one studies (3 = sequential; 11 = simultaneous, 7 = no CXL) were included. UDVA improved in all groups. CDVA improved more in the sequential group. SE change was greatest in the no CXL group and the refractive astigmatism reduced comparably in the sequential and no CXL groups but less in the simultaneous group. Kmax reduced in all groups. Only the sequential group showed no progression. Corneal haze was reported in 100%, 54.5%, and 57.1% studies, respectively. Safety and efficacy indices were 1.96 and 1.58, 1.41 ± 0.32 and 0.91 ± 0.41, and 1 and 0.82, respectively.

The sequential group showed greater improvement in CDVA, SE, and refractive astigmatism. Corneal haze was frequently reported in all protocols. Safety and efficacy indices were highest when CXL was performed before excimer laser and least when excimer laser was performed alone without CXL. [J Refract Surg. 2018;34(10):690-696.].