One-year clinical observation of epithelial-off accelerated corneal collagen cross-linking on the treatment of progressive keratoconus

AIM: To assess the clinical efficacy and safety of epithelial-off accelerated corneal collagen cross-linking(CXL)in the management of progressive keratoconus over 1 a period.METHODS:A retrospective pre-post self-controlled study. Data were collected from complete cases of 63 patients(84 eyes)with progressive keratoconus who underwent epithelial-off accelerated CXL between August 2018 and September 2021. Uncorrected visual acuity(UCVA), best corrected visual acuity(BCVA), refraction, corneal transparency, maximum keratometry(Kmax)of the anterior corneal surface, minimum corneal thickness, endothelial cell counts, and intraocular pressure(IOP)were analyzed preoperatively and at 1, 3, 6, and 12 mo postoperatively.RESULTS:No significant differences were observed in UCVA and spherical power before and after surgery(all P>0.05). However, there were significant differences in BCVA, cylinder power, Kmax, minimum corneal thickness, and IOP(all P<0.05). At 12 mo postoperatively, there were no significant differences in BCVA, cylinder power, minimum corneal thickness, and IOP compared with preoperative values(all P>0.05), while Kmax was decreased compared with preoperative value(P<0.05). At 1 mo postoperatively, the corneal endothelial cell count(2519.87±345.28 cells/mm2)was decreased compared with preoperative value(2693.63±313.39 cells/mm2; P<0.001). At 1 wk postoperatively, 22 eyes developed corneal haze(grade 0.5 to 1), and 15 eyes presented with linear corneal stromal opacity at 1 mo postoperatively. In 7 eyes, corneal opacity subsided within 3 to 6 mo after the operation, however, 5 eyes still exhibited corneal nebula or macula without affecting visual acuity.CONCLUSION: After epithelial-off accelerated CXL, the UCVA, BCVA and spherical diopter of patients remained stable over time. The astigmatism and corneal curvature temporarily increased and then gradually decreased. The cornea minimum thickness decreased initially but subsequently returned to preoperative levels. The corneal curvature at 6 and 12 mo after surgery was significantly lower than that before surgery, which could effectively prevent the progression of keratoconus. Despite potential localized corneal opacity and macular complications, as well as a possible decrease in corneal endothelial cell count, BCVA remained unaffected, demonstrating favorable safety outcomes.