title: Intrastromal corneal ring segments: visual outcomes from a large case series.
abstract: BACKGROUND
  To evaluate the clinical safety and efficacy of implanted Ferrara intrastromal corneal ring segments in a large sample of patients with ectatic corneal disease.
  
  
  METHODS
  Retrospective, consecutive case series.
  
  
  METHODS
  A total of 1073 eyes of 810 patients consecutively operated from January 2006 to July 2008 were evaluated.
  
  
  METHODS
  Two groups were created according to the type of ring implanted: Group 1 - patients implanted with the 160° of arc ring - and Group 2 - patients implanted with the 210° of arc ring.
  
  
  METHODS
  Uncorrected visual acuity, best-corrected visual acuity, keratometry, asphericity and pachymetry at the thinnest point of the cornea. All patients were evaluated using a corneal tomography (Pentacam, Oculus, Inc., Lynnwood, WA, USA).
  
  
  RESULTS
  For Group 1 patients, uncorrected visual acuity increased to 20/80, best-corrected visual acuity increased to 20/40, asphericity decreased to -0.35, spherical equivalent decreased to -2.26 D and keratometry decreased to 45.72 D (P < 0.001 for each compared with preoperative values). For Group 2 patients, uncorrected visual acuity increased to 20/130, best-corrected visual acuity increased to 20/60, asphericity decreased to -0.56, spherical equivalent decreased to -4.14 D and keratometry decreased to 48.10 D (P < 0.001 for each compared with preoperative values). The 210° intrastromal corneal ring segments reduced keratometry and asphericity more than the 160° intrastromal corneal ring segments did. The complication rate was 3.82%.
  
  
  CONCLUSIONS
  Ferrara intrastromal corneal ring segments implantation is safe and effective and has a low complication rate. It can effectively reduce the corneal steepening and improve uncorrected visual acuity and best-corrected visual acuity in patients with keratoconus.
authors: Paulo Ferrara Eye Clinic, Belo Horizonte, Brazil Fernandez-Vega Eye Institute, Oviedo, Spain. guilherme@ferrararing.com.br
authors: Guilherme
authors: G
authors: Ferrara
authors: Leonardo
authors: L
authors: Torquetti
authors: Paulo
authors: P
authors: Ferrara
authors: Jesús
authors: J
authors: Merayo-Lloves
mesh_terms: D000293:Adolescent; D000328:Adult; D003319:Corneal Stroma / Q000503:physiopathology / Q000601:surgery*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D007431:Intraoperative Complications; D007640:Keratoconus / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D019904:Polymethyl Methacrylate; D011183:Postoperative Complications; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D012029:Refraction, Ocular / Q000502:physiology*; D012189:Retrospective Studies; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology*; D014945:Wound Healing; D055815:Young Adult
chemical_list: D019904:Polymethyl Methacrylate