Mathew Francis1, Pooja Khamar2, Rohit Shetty2, Kanchan Sainani2, Rudy M M A Nuijts3, Bart Haex4, Abhijit Sinha Roy1. 1. Imaging, Biomechanics and Mathematical Modeling Solutions Lab, Narayana Nethralaya Foundation, Bangalore, India. 2. Department of Cornea and Refractive Surgery, Narayana Nethralaya, Bangalore, India. 3. University Eye Clinic Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands. 4. Director of Research Policy, Maastricht University, Maastricht, The Netherlands.
Abstract
Purpose: To simulate deformation amplitude after laser-assisted in situ keratomileusis (LASIK), small incision lenticule extraction (SMILE), and photorefractive keratectomy (PRK) with finite element models. Methods: Finite element simulations of air-puff applanation on LASIK, SMILE, and PRK models were performed on a cohort of normal eyes, which had undergone refractive treatments. Short- and long-term wound healing responses were considered for SMILE and LASIK models based on evidence of microdistortions in Bowman's layer and crimping of collagen fibers. First, inverse simulations were performed to derive the preoperative properties of the cornea. Using these properties and planned refractive treatment, postoperative air-puff deformation amplitude was predicted and compared with the in vivo measurements. Results: The predicted postoperative corneal stiffness parameters agreed very well with in vivo values of SMILE, LASIK, and PRK eyes. Intraclass correlations (ICC) were greatest in PRK eyes (ICC > 0.95). This agreement was lower for peak deformation amplitude and peak deflection amplitude in SMILE and LASIK eyes (ICC < 0.9). In PRK eyes, peak deformation and deflection amplitude predictions were the best relative to in vivo magnitudes. Also, linear correlation (r) between in vivo measurement and predicted biomechanical parameters indicated strong agreement between them (SMILE: r ≥ 0.89, LASIK: r ≥ 0.83, PRK: r ≥ 0.87). Conclusions: The is the first study to present predictive simulations of corneal deformation changes after different procedures. Patient-specific preoperative corneal biomechanical properties and finite element models were a significant determinant of accurate postoperative deformation amplitude prediction.
Purpose: To simulate deformation amplitude after laser-assisted in situ keratomileusis (LASIK), small incision lenticule extraction (SMILE), and photorefractive keratectomy (PRK) with finite element models. Methods: Finite element simulations of air-puff applanation on LASIK, SMILE, and PRK models were performed on a cohort of normal eyes, which had undergone refractive treatments. Short- and long-term wound healing responses were considered for SMILE and LASIK models based on evidence of microdistortions in Bowman's layer and crimping of collagen fibers. First, inverse simulations were performed to derive the preoperative properties of the cornea. Using these properties and planned refractive treatment, postoperative air-puff deformation amplitude was predicted and compared with the in vivo measurements. Results: The predicted postoperative corneal stiffness parameters agreed very well with in vivo values of SMILE, LASIK, and PRK eyes. Intraclass correlations (ICC) were greatest in PRK eyes (ICC > 0.95). This agreement was lower for peak deformation amplitude and peak deflection amplitude in SMILE and LASIK eyes (ICC < 0.9). In PRK eyes, peak deformation and deflection amplitude predictions were the best relative to in vivo magnitudes. Also, linear correlation (r) between in vivo measurement and predicted biomechanical parameters indicated strong agreement between them (SMILE: r ≥ 0.89, LASIK: r ≥ 0.83, PRK: r ≥ 0.87). Conclusions: The is the first study to present predictive simulations of corneal deformation changes after different procedures. Patient-specific preoperative corneal biomechanical properties and finite element models were a significant determinant of accurate postoperative deformation amplitude prediction.
Authors: William J Foster; Brian W Berg; Steven N Luminais; Amir Hadayer; Shlomit Schaal Journal: Am J Ophthalmol Date: 2022-03-28 Impact factor: 5.488