Abstract
Purpose :
To investigate the corneal stiffening effect after epithelium-off, accelerated corneal cross-linking (A-CXL(9*10)) with mechanical epithelial debridement (Epi-off-mech), transepithelial phototherapeutic keratectomy (Epi-off-tPTK) and wavefront-guided (Epi-off-tPRK), correcting high order aberrations (HOA).
Methods :
This observational study was retrospective, interventional and non-randomized. Patients with progressive keratoconus were indicated for A-CXL. In the Epi-off-mech group, the epithelium was removed using a hockey knife. For Epi-off-tPTK and Epi-off-tPRK epithelium thickness was measured and ablated using an excimer laser, whereas a correction of HOA were performed in the Epi-off-tPRK group. Corneal biomechanics and tomography were assessed by Corvis ST and Pentracam HR pre-CXL and one month post-CXL. For the analysis of the group comparisons, an ANOVA and a paired t-test were used.
Results :
Forty-five, 39 and 17 eyes were included in the Epi-off-mech, Epi-off-tPTK, and Epi-off-tPRK group, respectively. There were no significant differences between the groups preoperatively. Thinnest corneal thickness (TCT) decreased post-CXL significantly by -12.38, -20.67, and -42.82µm (p<0.001) in the Epi-off-mech, Epi-off-tPTK, and Epi-off-tPRK group. Nonetheless, corneal biomechanical stiffening was found in the Epi-off-mech and Epi-off-tPTK group indicated by an increased biomechanical corrected IOP (bIOP) and stress-strain index (SSI) as well as a decreased integrated radius (IIR, all P<0.05). In the group with Epi-off-tPRK, corneal stiffening was detected with the increased bIOP and decreased IIR (all P<0.05), only in this group the HOA improved statistically significantly (P<0.001). Between the groups, there were no significant differences in biomechanical parameters but TCT was significantly reduced in the groups with laser ablation.
Conclusions :
Corneal stiffening occurs after A-CXL independently of the epithelium removal procedure. The increase of corneal stiffness was less pronounced in the Epi-off-tPRK due to the higher decrease in corneal thickness. However, the HOA decreased stronger, indicating a potential improvement in visual acuity.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.