Corneal Cap Thickness and Its Effect on Visual Acuity and Corneal Biomechanics in Eyes Undergoing Small Incision Lenticule Extraction

• Published in: Journal of ophthalmology 2018-01, Vol.2018 (2018), p.1-7
• Main Authors: Chen, Kaijian, Liu, Lina, Yu, Ting, Liu, Ting, Bai, Ji
• Format: Article
• Language: English
• Subjects: Biomechanics; Clinical Study; Cornea; Lasers; Patients; Postoperative period; Statistical analysis; Surgery; Visual acuity
• ISSN: 2090-004X; 2090-0058
• DOI: 10.1155/2018/6040873

Purpose. To evaluate the effect of corneal cap thickness on visual acuity and corneal biomechanics in small incision lenticule extraction (SMILE) for the treatment of myopia. Methods. Forty eyes of 20 patients undergoing SMILE for the treatment of myopia were enrolled in this prospective controlled study. The patients with 510 μm–560 μm central corneal thickness (CCT) and a refractive spherical equivalent of −3.00 D to −8.00 D were included. It was designed randomly to undergo SMILE with a 110 μm cap thickness in one eye and 150 μm cap thickness in the other. Ophthalmic examinations included best-corrected and uncorrected visual acuity (UCVA); refractive status, contrast sensitivity, and objective visual quality were evaluated at 2 h, 4 h, and 24 h postoperatively; while at 3 months after the procedure, corrected intraocular pressure (IOP), higher order aberrations (HOAs), and morphologic modifications of corneal architecture of both eyes were assessed. Results. Compared with the 150 μm group, the incidence of OBL was significantly higher in the 110 μm cap thickness group (P=0.004), and UCVA, Strehl ratio (SR), objective scatter index (OSI), modulation transfer function (MTF) cutoff frequency, and photopic and scotopic contrast sensitivity at medium spatial frequency were all significantly better in 110 μm group at 2 h and 24 h postoperatively (P