Biomechanical changes in keratoconus after customized stromal augmentation

Sana Niazi; Jorge Alió Del Barrio; Farideh Doroodgar; Azad Sanginabadi; Cyrus Alinia; Seyed Javad Hashemian; Hassan Hashemi; Jorge L Alio

doi:10.4103/tjo.TJO-D-23-00155

Biomechanical changes in keratoconus after customized stromal augmentation

Taiwan J Ophthalmol. 2024 Feb 20;14(1):59-69. doi: 10.4103/tjo.TJO-D-23-00155. eCollection 2024 Jan-Mar.

Authors

Sana Niazi^{1

2}, Jorge Alió Del Barrio³, Farideh Doroodgar^{1

2}, Azad Sanginabadi⁴, Cyrus Alinia⁵, Seyed Javad Hashemian⁶, Hassan Hashemi⁷, Jorge L Alio^{8

9}

Affiliations

¹ Translational Ophthalmology Research Center, Tehran University of Medical Sciences, Tehran, Iran.
² Negah Aref Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
³ Cornea, Cataract and Refractive Surgery Unit, Vissum Corporación, Alicante, Spain.
⁴ Department of Optometry, Iran University of Medical Sciences, Tehran, Iran.
⁵ Department of Public Health, School of Public Health, Urmia University of Medical Sciences, Urmia, Iran.
⁶ Eye Research Center, Five Senses Institute, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran.
⁷ Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran.
⁸ Division of Ophthalmology, Universidad Miguel Hernández, Alicante, Spain.
⁹ Vissum Miranza Alicante, Alicante, Spain.

Abstract

Purpose: To verify corneal biomechanical changes, poststromal augmentation using myopic small-incision lenticule extraction's (SMILEs) lenticules in advanced keratoconus (KCN) through Corvis ST (Oculus, Wetzlar, Germany).

Materials and methods: A clinical trial enrolled 22 advanced KCN patients. We implanted lenticules exceeding 100 μ according to a nomogram and evaluated biomechanical factors through Corvis ST at 3-, 6-, and 24-month postimplantation. We examined parameters during the first applanation (A1), second applanation (A2), highest concavity (HC)/max concavity events, and Vinciguerra screening parameters, as recently established criteria derived from the ideal blend of diverse biomechanical and ocular factors and formulated through the application of logistic regression. Regression analyses explored relationships with age, mean keratometry value, thickness, sphere, cylinder, and best-corrected visual acuity.

Results: Patients were well matched for age, intraocular pressure, and central corneal thickness (CCT). The mean spherical equivalent decreased from -13.48 ± 2.86 Diopters (D) to -8.59 ± 2.17 D (P < 0.007), and mean keratometry decreased from 54.68 ± 2.77 D to 51.95 ± 2.21 D (P < 0.006). Significant increases were observed in HC time (HCT), Radius-central curvature radius at the HC state-, peak distance (PD) during HC state, CCT, first applanation time, and stiffness parameter (A1T and SP-A1), whereas HC deformation amplitude, maximum deformation amplitude ratio at 2 mm, Corvis Biomechanical Index (CBI), integrated radius (IR), second applanation deformation amplitude (A2DA), first applanation velocity and deflection amplitude (A1V and A1DeflA) significantly decreased postlenticule implantation. Multivariable regression revealed age positively correlated with SP-A1 (P = 0.003) and negatively with HC delta Arc length (P = 0.007). Mean K positively correlated with CCT (P = 0.05) and negatively with CBI (P = 0.032). Best-corrected visual acuity positively correlated with HCT (P = 0.044), and the cylinder positively correlated with PD (P = 0.05) and CCT (P = 0.05) whereas negatively with IR (P = 0.025).

Conclusions: Stromal augmentation using myopic SMILE lenticules induces significant corneal biomechanical changes in KCN.

Keywords: Cornea; corneal stroma; keratoconus; stromal lenticule; tissue donors; transplantation.

Publication types

Clinical Trial