Accelerated corneal cross-linking with application of isotonic riboflavin under pedicled corneal epithelial flap for thin keratoconus

AIM: To evaluate the safety and efficacy of accelerated corneal cross-linking(A-CXL)with application of isotonic riboflavin under pedicled corneal epithelial flap in the treatment of thin keratoconus(corneal thickness less than 400 μm after epithelial removal).METHODS: Retrospective study. A total of 46 patients(74 eyes)with keratoconus treated in the refractive surgery department of Ineye Hospital of Chengdu University of TCM from September 2017 to December 2020 were enrolled. According to the preoperative thinnest corneal thickness(TCT), the patients were divided into two groups: 16 patients(20 eyes)with TCT ranging from 400 to <450 μm underwent accelerated corneal cross-linking with application of isotonic riboflavin under pedicled corneal epithelial flap, and the surgical method involves creating a pedicled corneal epithelial flap and lifting it, applying isotonic riboflavin eye drops, repositioning the corneal epithelial flap, performing ultraviolet irradiation and then using corettage of corneal epithlial flap after irradiation. Another 30 patients(54 eyes)with TCT ≥450 μm underwent epithelial-off A-CXL surgery. After follow-up for 12 mo, the results of best corrected visual acuity(BCVA), Sirius three-dimensional corneal topography, and corneal endothelial cell density were collected before and after surgery.RESULTS: At 12 months post-surgery, patients in the pedicled corneal epithelial flap group showed no significant difference in Kmax compared with pre-surgery(P>0.005), while patients in the epithelial-off group showed a significant reduction in Kmax compared with pre-surgery(P<0.005). For both groups, there were no significant differences in BCVA(LogMAR), corneal anterior and posterior surface curvatures(K1, K2), and corneal endothelial cell density at 12 mo post-surgery compared with pre-surgery(all P>0.005). The comparisons of the changes in various parameters between 12 mo post-surgery and pre-surgery for both groups showed no significant differences(all P>0.05).CONCLUSION: Accelerated corneal cross-linking with application of isotonic riboflavin under pedicled corneal epithelial flap surgery is safe and feasible for patients with thin keratoconus, achieving similar control of keratoconus progression as epithelial-off A-CXL.