Changes In Corneal Biomechanics Following Corneal Allogenic Ring Segment Implantation

To assess the impact of corneal allogenic ring segment (CAIRS) implantation in patients with keratoconus on corneal biomechanical parameters over a two-year long follow-up period.

Department of Ophthalmology, Dresden University Hospital, Dresden, Germany

This ongoing prospective observational clinical study included 23 eyes from 21 patients who underwent CAIRS implantation. Corneal biomechanics were quantified using the Corvis ST (Oculus, Wetzlar, Germany). Corneal biomechanic indices included in the analysis were the deformation amplitude ratio at 2 mm (DA-ratio), the integrated radius (IR), the stiffness parameter at first applanation (SP-A1), the stress-strain-index (SSI), and the Ambrósio relational thickness to the horizontal profile (ARTh). Patients were examined preoperatively as well as 3 months, 6 months, 1 year, and 2 years post-operatively. Wilcoxon paired sample signed-rank test was used to assess the difference between the preoperative values and the follow-ups.

Compared to the preoperative values, the IR increased from 13.6 mm^-1 to 16.6 mm^-1 (p = 0.024) and the ARTh decreased from 92.8 to 56.2 (p = 0.045) at the 6-month follow-up (preliminary results, n = 14). DA-ratio showed a tendency to increase, while SSI and SP-A1 to decrease, but these changes did not reach statistical significance. Although 2-year data are not yet available from all patients in this ongoing study, trends continued to be observed throughout the 2-year follow-up period.

Preliminary results indicate that CAIRS implantation in keratoconus eyes induces statistically significant and lasting changes in corneal biomechanical parameters measured by Corvis ST. Further studies are necessary to determine the viability of the Corvis ST in reliably assessing corneal biomechanics following CAIRS implantation.