Purpose
The purpose of this article was to assess the safety and efficacy of transepithelial corneal collagen cross-linking (epithelial on) versus standard (epithelial off) technique in halting the progression of keratoconus.
Patients and methods
A prospective nonrandomized interventional comparative standard technique was conducted, which divided 40 patients into two groups: in group A, 34 eyes of 24 patients were enrolled and treated by transepithelial cross-linking, and in group B, 28 keratoconus eyes of 16 patients were included and treated by the standard technique. In group A, a solution of riboflavin 0.1%, dextran T500, trometamol, and EDTA (trans-Ribo) was instilled. In group B the epithelium was removed and riboflavin 0.1 solution (10 mg of riboflavin-5-phosphate in a 20% dextran T500 10 ml solution Ricrolin was instilled. Ultraviolet A irradiation (Food and Drug Administration approval) Avedro system was used with total energy 7.2, power intensity 30 mW, induction time 10 min, ultraviolet time continuous 4 min, and ultraviolet time pulse 8 min, but in transepithelial cross-linking, the intensity was 45 mW. Preoperative and postoperative assessments were performed at baseline and 3, 6, and 12 months postoperatively.
Results
Group A showed statistically highly significant differences between mean uncorrected visual acuity (UCVA) and mean UCVA at first, sixth, and 12th months postoperatively. In group B, there were statistically highly significant differences between mean UCVA preoperatively and the mean UCVA at first, sixth, and 12th months postoperatively. In group A, there were statistically significant differences between mean Km (mean k power) preoperatively and mean Km at the first and at 12th months postoperatively, whereas in group B, there were statistically significant differences between mean Km preoperatively and the mean Km at first month and statistically insignificant difference at third, sixth, and 12th months postoperatively.
Conclusion
Both epithelial-on and epithelial-off techniques appeared to correct best-corrected visual acuity but epithelial-off technique was more effective in reduction of KM, astigmatism, -value and anterior elevation. Moreover, epithelial off showed to halt keratoconus progression more than epithelial-on technique.