Hun Lee1, Cynthia J Roberts1, Tae-Im Kim1, Renato Ambrósio1, Ahmed Elsheikh1, David Sung Yong Kang2. 1. From the Department of Ophthalmology (Lee), International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, the Eyereum Eye Clinic (Kang), Seoul, and the Institute of Vision Research (Lee, Kim), Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea; the Department of Ophthalmology & Visual Science and Department of Biomedical Engineering (Roberts), Ohio State University, Columbus, Ohio, USA; Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, Brazil; the School of Engineering (Elsheikh), University of Liverpool, Liverpool, United Kingdom. 2. From the Department of Ophthalmology (Lee), International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, the Eyereum Eye Clinic (Kang), Seoul, and the Institute of Vision Research (Lee, Kim), Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea; the Department of Ophthalmology & Visual Science and Department of Biomedical Engineering (Roberts), Ohio State University, Columbus, Ohio, USA; Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, Brazil; the School of Engineering (Elsheikh), University of Liverpool, Liverpool, United Kingdom. Electronic address: kangeye@eyereum.com.
Abstract
PURPOSE: To evaluate the changes in biomechanically corrected intraocular pressure (IOP) and new dynamic corneal response parameters measured by a dynamic Scheimpflug analyzer before and after transepithelial photorefractive keratectomy (PRK) and femtosecond laser-assisted laser in situ keratomileusis (LASIK). SETTING: Yonsei University College of Medicine and Eyereum Eye Clinic, Seoul, South Korea. DESIGN: Retrospective case series. METHODS: Medical records of patients having transepithelial PRK or femtosecond-assisted LASIK were examined. The primary outcome variables were biomechanically corrected IOP and dynamic corneal response parameters, including deformation amplitude ratio 2.0 mm, stiffness parameter at first applanation, Ambrósio relational thickness through the horizontal meridian, and integrated inverse radius before the procedure and 6 months postoperatively. RESULTS: Of the 129 patients (129 eyes) in the study, 65 had transepithelial PRK and 64 had femtosecond-assisted LASIK. No significant differences in biomechanically corrected IOP were noted before and after surgery. The deformation amplitude ratio 2.0 mm and integrated inverse radius increased, whereas the stiffness parameter at first applanation and the Ambrósio relational thickness through the horizontal meridian decreased after surgery (P < .001). The changes in deformation amplitude ratio 2.0 mm and integrated inverse radius were smaller in transepithelial PRK than femtosecond-assisted LASIK (P < .001). Using analysis of covariance, with refractive error change or corneal thickness change as a covariate, the changes in deformation amplitude ratio 2.0 mm and integrated inverse radius were smaller in transepithelial PRK than femtosecond-assisted LASIK (P < .001). CONCLUSIONS: The dynamic Scheimpflug analyzer showed stable biomechanically corrected IOP measurement before and after surgery. The changes in dynamic corneal response parameters were smaller with transepithelial PRK than with femtosecond-assisted LASIK, indicating less of a biomechanical effect with transepithelial PRK.
PURPOSE: To evaluate the changes in biomechanically corrected intraocular pressure (IOP) and new dynamic corneal response parameters measured by a dynamic Scheimpflug analyzer before and after transepithelial photorefractive keratectomy (PRK) and femtosecond laser-assisted laser in situ keratomileusis (LASIK). SETTING: Yonsei University College of Medicine and Eyereum Eye Clinic, Seoul, South Korea. DESIGN: Retrospective case series. METHODS: Medical records of patients having transepithelial PRK or femtosecond-assisted LASIK were examined. The primary outcome variables were biomechanically corrected IOP and dynamic corneal response parameters, including deformation amplitude ratio 2.0 mm, stiffness parameter at first applanation, Ambrósio relational thickness through the horizontal meridian, and integrated inverse radius before the procedure and 6 months postoperatively. RESULTS: Of the 129 patients (129 eyes) in the study, 65 had transepithelial PRK and 64 had femtosecond-assisted LASIK. No significant differences in biomechanically corrected IOP were noted before and after surgery. The deformation amplitude ratio 2.0 mm and integrated inverse radius increased, whereas the stiffness parameter at first applanation and the Ambrósio relational thickness through the horizontal meridian decreased after surgery (P < .001). The changes in deformation amplitude ratio 2.0 mm and integrated inverse radius were smaller in transepithelial PRK than femtosecond-assisted LASIK (P < .001). Using analysis of covariance, with refractive error change or corneal thickness change as a covariate, the changes in deformation amplitude ratio 2.0 mm and integrated inverse radius were smaller in transepithelial PRK than femtosecond-assisted LASIK (P < .001). CONCLUSIONS: The dynamic Scheimpflug analyzer showed stable biomechanically corrected IOP measurement before and after surgery. The changes in dynamic corneal response parameters were smaller with transepithelial PRK than with femtosecond-assisted LASIK, indicating less of a biomechanical effect with transepithelial PRK.
Authors: Majid Moshirfar; Mahsaw N Motlagh; Michael S Murri; Hamed Momeni-Moghaddam; Yasmyne C Ronquillo; Phillip C Hoopes Journal: Med Hypothesis Discov Innov Ophthalmol Date: 2019