This randomized sham-controlled trial evaluated the safety and efficacy of corneal crosslinking (CXL) for patients who developed corneal ectasia after laser refractive surgery.
Study design
Conducted at 11 sites across the U.S., the trial randomized 179 subjects to standard epithelium-off CXL or sham treatment. The treatment group received standard Dresden protocol CXL (riboflavin 0.1%), and the sham group received riboflavin alone without removal of the epithelium.
The primary endpoint was change in maximum topography-derived keratometry value (Kmax).
Outcomes
At 1 year postop, mean Kmax decreased by 0.7 D in CXL eyes, whereas sham eyes had a mean increase of 0.6 D (P<0.0001). CDVA and UDVA improved in the CXL group, but declined in the control group (both P<0.001).
Corneal haze—a well-documented complication of CXL—developed in 62 eyes (68%), but resolved in all but 5 patients by the end of follow-up. One severe adverse event of epithelial ingrowth beneath the LASIK flap (on postoperative day 35) was reported in the CXL treatment group. The condition was resolved following removal of the ingrown cells.
Limitations
A 1-year follow-up is fairly short and may not allow investigators to observe long-term changes in these eyes. Additionally, sham eyes were handled differently than treatment eyes as their epithelium was not debrided. However, this was unlikely to have made a difference in outcomes.
Control eyes were allowed to cross over into the treatment group after 3 months. Therefore, only 2 control eyes were available at 12 months. Finally, the authors were unable to determine if there were any differences in outcomes for ectasia after LASIK vs. PRK.
Clinical significance
This study, which was the basis of the July 2016 FDA approval for the Avedro CXL system for post-refractive keratectasia, should assuage concerns regarding the efficacy of CXL in slowing progression of this condition. The procedure also appears to provide visual and optical benefits along with an excellent safety profile.