Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Clinical Trial
. 2024 Feb 20;14(1):59-69.
doi: 10.4103/tjo.TJO-D-23-00155. eCollection 2024 Jan-Mar.

Biomechanical changes in keratoconus after customized stromal augmentation

Sana Niazi  1   2 , Jorge Alió Del Barrio  3 , Farideh Doroodgar  1   2 , Azad Sanginabadi  4 , Cyrus Alinia  5 , Seyed Javad Hashemian  6 , Hassan Hashemi  7 , Jorge L Alio  8   9
Affiliations
Clinical Trial

Biomechanical changes in keratoconus after customized stromal augmentation

Sana Niazi et al. Taiwan J Ophthalmol. .

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.

PubMed Disclaimer

Conflict of interest statement

Prof. Jorge L. Alio, an international editorial board member at Taiwan Journal of Ophthalmology, had no role in the peer review process of or decision to publish this article. The other authors declared no conflicts of interest in writing this paper.

Figures

Figure 1
Figure 1
Nomogram of first-stage treatment for advanced keratoconus using stromal donor lenticules during myopic small incision lenticule extraction surgery. D = Diopters
Figure 2
Figure 2
Form of lenticule
Figure 3
Figure 3
Corvis ST overview display
Figure 4
Figure 4
The established parameters that presented significant differences with the normal population, among preoperatively (keratoconus eyes) and postoperatively (eyes with lenticules) and during three courses of follow-up and correlated parameters (from left to right, respectively). HCDA = Highest concavity deformation amplitude, DA Ratio Max = Maximum deformation amplitude ratio, ARTH = Ambrósio’s relational thickness, IR = Integrated radius, CBI = Corvis biomechanical index, CCT = Central corneal thickness, HCT = Highest concavity time, RAD = Radius, PD = Peak distance
See this image and copyright information in PMC

References

    1. Vega-Estrada A, Mimouni M, Espla E, AlióDel Barrio J, Alio JL. Corneal epithelial thickness intrasubject repeatability and its relation with visual limitation in keratoconus. Am J Ophthalmol. 2019;200:255–62. - PubMed
    1. Niazi S, Jiménez-García M, Findl O, Gatzioufas Z, Doroodgar F, Shahriari MH, et al. Keratoconus diagnosis: From fundamentals to artificial intelligence: A systematic narrative review. Diagnostics (Basel) 2023;13:2715. - PMC - PubMed
    1. Sachdev GS, Sachdev R, Sachdev MS. Intra corneal ring segment implantation with lenticule assisted stromal augmentation for crosslinking in thin corneas. Am J Ophthalmol Case Rep. 2020;19:100726. - PMC - PubMed
    1. Hafezi F, Kling S, Gilardoni F, Hafezi N, Hillen M, Abrishamchi R, et al. Individualized corneal cross-linking with riboflavin and UV-A in ultrathin corneas: The sub400 protocol. Am J Ophthalmol. 2021;224:133–42. - PubMed
    1. Pedrotti E, Chierego C, Bonacci E, De Gregorio A, De Rossi A, Zuliani A, et al. New treatments for keratoconus. Int Ophthalmol. 2020;40:1619–23. - PubMed

Publication types