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Updated: Apr 2, 2026
Three Different Protocols of Corneal Collagen Crosslinking in Keratoconus: Conventional, Accelerated and Iontophoresis
Published on: November 12, 2015
Variation in corneal biomechanical properties following continuous cross-linking treatment
ChenHao Zhao1,2,3, XinYu Yao1, YeWei Zhao1
1National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, No. 270 Xueyuanxi Road, Wenzhou, 325027, Zhejiang, China.
Background:
This retrospective study aimed to evaluate the efficacy of transepithelial accelerated corneal cross-linking (transEpi ACXL) when applied separately or combined with phototherapeutic keratectomy (transPTK ACXL) in keratoconic eyes using biomechanical parameters.
Methods:
The study included eyes with progressive keratoconus treated with either continuous transEpi ACXL or transPTK ACXL with 6 months follow-up. The following parameters were assessed preoperatively and 6 months postoperatively: biomechanically corrected intraocular pressure (bIOP), maximum and mean keratometry (Kmax and Km), minimum and central corneal thickness (MCT and CCT), corneal coma, best-corrected visual acuity (BCVA), deformation amplitude ratio at 2 mm nasal/temporal (DAR2), integrated inverse radius (IIR), stiffness parameter at first applanation (SP-A1), highest concavity time (HCT) and two versions of stress-strain index (SSIv1 and SSIv2).
Results:
A total of 75 eyes from 72 patients were included (31 in the transEpi ACXL group and 44 in the transPTK ACXL group). The two groups were comparable in age (23.0 ± 5.0 vs. 21.3 ± 5.2 years) and TKC grade distribution (grades 1-4), with no statistically significant between-group differences (P = 0.321 and 0.766, respectively). Both groups exhibited significant reductions in IIR, and increases in SSIv1 and SSIv2 (all P < 0.05). The improvements in Kmax, coma, and SSIv2 were greater in the transPTK ACXL group than in the transEpi ACXL group (all P < 0.05). The relative difference in SSIv2 (SSIv2Rdif) exceeded those of other biomechanical parameters in both groups (transEpi ACXL: SSIv2Rdif > DAR2Rdif, IIRdif; transPTK ACXL: SSIv2Rdif > DAR2Rdif, IIRRdif, SP-A1Rdif, HCTRdif, and SSIv1Rdif, all P < 0.05).
Conclusions:
TransPTK ACXL resulted in better biomechanical and visual benefits in comparison with transEpi ACXL 6 months after treatment. SSIv2 demonstrated superior performance in assessing the efficacy of corneal cross-linking.
