Abstract
PURPOSE: To compare the safety and efficacy of standard 30 min epithelium-off cross-linking (CXL) versus photorefractive keratectomy (PRK) combined with accelerated epithelium-off cross-linking (AXL) for the treatment of progressive keratoconus (CXL-Plus). METHODS: This study was a prospective multicentre comparative clinical study. A total of 125 eyes of 75 patients with grade 1 keratoconus and documented progression were divided into two groups. Group A included 58 eyes treated with standard CXL. Group B included 67 eyes treated with combined PRK and AXL. The recorded data included UDVA, CDVA, subjective and objective refraction, keratometry and pachymetry using corneal topographies preoperatively and postoperatively at 3, 6, 12 and 24 months of follow-up. RESULTS: In group A, at 24 months of UDVA and CDVA were improved from 1.12 ± 0.38 and 0.58 ± 0.42 to 0.66 ± 0.20 and 0.20 ± 0.12 (LogMAR±SD). The spherical equivalent was reduced from 4.03 ± 1.18 to 1.78 ± 1.04 D. The cylinder reduction was 0.32 ± 0.19 D. In group B, at 24 months of UDVA and CDVA were improved from 1.26 ± 0.52 and 0.68 ± 0.36 to 0.58 ± 0.28 and 0.20 ± 0.16 (LogMAR ± SD). The spherical equivalent was reduced from 4.23 ± 0.95 to 1.92 ± 0.74 D. The cylinder reduction was ±1.76 D. CONCLUSION: Surprisingly, standard CXL showed close results to CXL-Plus at the 24th follow-up month. Standard CXL acted as a stabilizing procedure associated with a late myopic component reduction. CXL-Plus acted as a refractive and stabilizing procedure with an early effect on both the myopic and the astigmatic component but no later improvements. Standard CXL seems to be more powerful than AXL in its long-term effect. Therefore, in the future, we want to test the combination of PRK with standard CXL.