title: Clinical evaluation of corneal biomechanical parameters after posterior chamber phakic intraocular lens implantation.
abstract: OBJECTIVE
  The aim of this study was to quantitatively assess the changes in corneal biomechanics after posterior chamber phakic intraocular lens (Visian ICL; STAAR Surgical) implantation for normal and keratoconic subjects.
  
  
  METHODS
  We retrospectively examined 29 eyes of 16 consecutive patients (mean age ± SD, 32.4 ± 7.3 years) undergoing implantable collamer lens (ICL) implantation through a 3.0-mm temporal corneal incision. We longitudinally assessed the values of corneal hysteresis (CH) and corneal resistance factor (CRF) using an Ocular Response Analyzer. We also investigated the relationship between these biomechanical parameters and central corneal thickness (CCT) preoperatively, and at 1 week, 1 month, and 3 months postoperatively.
  
  
  RESULTS
  The CH was 9.2 ± 1.4 mm Hg preoperatively, and 9.2 ± 1.4 mm Hg, 9.3 ± 1.7 mm Hg, and 8.8 ± 1.3 mm Hg at 1 week, 1 month, and 3 months postoperatively, respectively. The CRF was 8.4 ± 1.6 mm Hg preoperatively, and 9.0 ± 1.5 mm Hg, 8.8 ± 1.7 mm Hg, and 8.8 ± 1.6 mm Hg, at 1 week, 1 month, and 3 months postoperatively, respectively. Multiple comparisons demonstrated no significant differences between measurements made preoperatively and postoperatively (P > 0.05, Dunnett test). Both CH and CRF were significantly correlated with CCT 3 months postoperatively [Spearman correlation coefficient (r) = 0.48, P = 0.01 for CH; r = 0.84, P < 0.001 for CRF].
  
  
  CONCLUSIONS
  We found no significant changes in CH or CRF after ICL implantation, not only in normal eyes but also in keratoconic eyes, suggesting that this surgical technique does not significantly affect corneal biomechanical factors. The CCT may play some role in corneal biomechanics even in eyes undergoing ICL implantation.
authors.affiliation: *Department of Ophthalmology, University of Kitasato School of Medicine, Kanagawa, Japan; and †Department of Ophthalmology, Faculty of Medicine, Minia University Hospitals, Minia, Egypt.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Ali
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Kamiya
authors.forename: Kimiya
authors.initials: K
authors.lastname: Shimizu
authors.forename: Akihito
authors.initials: A
authors.lastname: Igarashi
authors.forename: Rie
authors.initials: R
authors.lastname: Ishii
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology*; D003315:Cornea / Q000502:physiology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D032801:Iridectomy; D007498:Iris / Q000601:surgery; D007640:Keratoconus / Q000503:physiopathology / Q000601:surgery*; D053844:Lasers, Solid-State; D019654:Lens Implantation, Intraocular; D008297:Male; D008875:Middle Aged; D054120:Phakic Intraocular Lenses; D012189:Retrospective Studies; D055815:Young Adult