The Corvis ST – Biomechanical changes after Stromal Enhancement in Keratoconus
Farideh Doroodgar, MD1 *, Jorge L. Alio, MD, PhD FEBO2 , Sana Niazi, MS3
- Negah Specialty Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Division of Ophthalmology, Universidad Miguel Hernández, Alicante, Spain Vissum Miranza Alicante, Spain
- Department of Ophthalmology, Shahid Beheshti University of Medical Sciences and Health Services, Tehran, Iran
Abstract: To verify the corneal biomechanical changes after stromal enhancement in keratoconus patients, by stromal lenticules of myopic SMILE patients, using Corvis ST (Oculus, Wetzlar, Germany).
Methods: Excluded from entry were subjects with history or signs of systemic or eye diseases other than keratoconus, or inability to conform to the investigation necessities. These patients were successfully scheduled for immediate (by four h) implantation of the extracted lenticule of a healthy donor with high myopia 9.75≤ SE ≤ 11 diopters using the VisuMax (Carl Zeiss Meditec, Jena, Germany) SMILE software. The process of Customized Stromal lenticule implantation (CuSLI) being performed, then Corvis ST images were obtained at 3, 6,12 months and compared with parameters which had obtained as baseline before implantation of the lenticules in eyes with advanced keratoconus. Corvis ST corneal biomechanical factors were: Biomechanically corrected Intraocular pressure (bIOP), First applanation parameters(A1), Second applanation parameters (A2), Maximum (Max) or Highest concavity (HC)parameters, Vinciguerra screening (Vs) parameters, and Corvis biomechanical index (CBI).
Results: We analyzed the 22 eyes of 22 keratoconus individuals. Mean [ ± standard deviation (SD)] age of patients was 36 ± 3 years, and (%36.4) were male. Both HC (max) Deformation Amplitude (MDA) and Corvis biomechanical index (CBI)had high Youden index (0.86, 0.82). With a cut-off value 1.1 for HC (max) Deformation Amplitude (MDA) with 88.36% sensitivity and 100% specificity. Area Under ROC is 0.962 ± 0.027 (0.909 – 1 ,95%CI) and P-value<0. 001.With the Corvis biomechanical index (CBI) cut-off value of 0.61, with 90.91% sensitivity and 90.91% specificity. Area Under ROC is 0.067 ± 0.038 (0 - 0.142 ,95%CI) and P-value<0.001.
Conclusion: Stromal enhancement induces significant effects in corneal biomechanical properties in cases with keratoconus.
