Evaluation of Corneal Biomechanics After Excimer Laser Corneal Refractive Surgery in High Myopic Patients Using Dynamic Scheimpflug Technology. Issue 6 (November 2017)

• Record Type: Journal Article
• Authors: Hashemi, Hassan; Asgari, Soheila; Mortazavi, Mahdi; Ghaffari, Reza
• Is Part Of: Eye & contact lens. Volume 43:Issue 6(2017:Nov.)
• Publication Date: 2017-11
• Subjects: High myopia -- Femtosecond assisted refractive surgery -- Photorefractive keratectomy -- Corneal biomechanics -- Corvis ST; Contact lenses -- Periodicals; Intraocular lenses -- Periodicals; Orthokeratology -- Periodicals; Anterior segment (Eye) -- Diseases -- Periodicals; 617.7523
• DOI: 10.1097/ICL.0000000000000280
• Languages: English
• ISSNs: 1542-2321

Abstract

Abstract : Objective: To compare the effect of femtosecond-assisted thin flap laser-assisted in situ keratomileusis (FS-LASIK) and photorefractive keratectomy with mitomycin-C (PRK-MMC) in highly myopic patients (>7.0 D [D]) on corneal biomechanical parameters. Methods: In this prospective comparative interventional case series, 60 patients (30 patients in each group) with a manifest refractive spherical equivalent (MRSE) greater than 7.0 D were enrolled. Corvis ST parameters were measured before and at 3 and 6 months postoperatively. Results: Preoperatively, mean MRSE was −8.65±1.51 D in FS-LASIK and −8.04±1.70 D in PRK-MMC groups ( P =0.149), and corneal thickness was 570.67±36.79 μm and 507.12±32.55 μm, respectively ( P <0.001). At 6 months, both groups showed significantly higher applanation (A) 2 time and A2-velocity ( P <0.05 in both), whereas intraocular pressure (IOP), corrected IOP, A1 time, A1-velocity, and radius at highest concavity were significantly reduced ( P <0.05 in all). In the FS-LASIK group, there was a significant increase in deformation amplitude (DA) ( P =0.001), and significant decreases in A2-length ( P =0.004). Peak distance increased in the PRK-MMC group ( P =0.029). At 6 months, after controlling for fellow eye correlations and preoperative corneal thickness between the two groups, decreases in IOP, A1-time, A2-length and radius, and the increase in DA was greater in FS-LASIK. Conclusion: This study demonstrated significant changes in Corvis ST ocular biomechanical metrics after both PRK-MMC and FS-LASIK in high myopic patients, indicating the significant effect of excimer laser refractive surgery on corneal biomechanical properties. However, changes that occur with FS-LASIK are more significant than with PRK-MMC. Further randomized studies are needed to better characterize the pattern of biomechanical changes associated with each type of surgery. Abstract : Supplemental Digital Content is Available in the Text.