title: Modified intracorneal ring segment implantations (INTACS) for the management of moderate to advanced keratoconus: efficacy and complications.
abstract: OBJECTIVE
  To evaluate the safety and efficacy of modified intracorneal ring segment implantation (INTACS) in the management of moderate and advanced keratoconus (KCN).
  
  
  METHODS
  A modified procedure of intracorneal ring segment (INTACS) implantation was performed in eyes with moderate to advanced keratoconus that were intolerant to contact lens or spectacle correction. The main outcome measures were uncorrected visual acuity (UCVA), best spectacle corrected visual acuity (BSCVA), refraction, and keratometry. The preoperative values were compared with the values 6 and 12 months postoperatively.
  
  
  RESULTS
  Implantation was performed on 20 eyes of 15 patients; 9 were female and 6 were male. The mean age was 30.2 years (SD +/- 5.44; range, 23-40). At the 6-month follow-up, UCVA improved from 20/154 (SD +/- 0.11) preoperatively to 20/28 (SD +/- 0.21) postoperatively (P < 0.05); BCSVA improved from 20/37 (SD +/- 0.21) preoperatively to 20/22 (SD +/- 0.13) postoperatively (P < 0.05). Spherical refractive error improved from -3.38 D (SD +/- 3.12) to -1.15 D (SD +/- 1.84); cylindrical refractive error improved from -3.75 (SD +/- 2.04) preoperatively to -1.21 (SD +/- 0.84) postoperatively (P < 0.05); average keratometry decreased from 49.50 D (SD +/- 1.64) preoperatively to 46.35 D (SD +/- 1.50) postoperatively. The changes remained stable to the 12-month follow-up. There was 1 case of anterior chamber perforation. There were 6 eyes that had ring exposure secondary to corneal thinning over the implants 3-6 months postoperatively, and a dense corneal infiltrate developed in 1 patient at 7 months postoperatively.
  
  
  CONCLUSIONS
  The procedure appears to be effective in improving UCVA and BSCVA of patients with clinical keratoconus. In our small study group, however, there were significant (6/20) postoperative problems with regards to thinning and ring exposure.
authors.affiliation: Department of Ophthalmology, New York University Medical School, New York, New York, USA. laservision@inernet.gr
authors.forename: A John
authors.initials: AJ
authors.lastname: Kanellopoulos
authors.forename: Lawrence H
authors.initials: LH
authors.lastname: Pe
authors.forename: Henry D
authors.initials: HD
authors.lastname: Perry
authors.forename: Eric D
authors.initials: ED
authors.lastname: Donnenfeld
mesh_terms: D000328:Adult; D001672:Biocompatible Materials; D003319:Corneal Stroma / Q000601:surgery*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D019904:Polymethyl Methacrylate; D011446:Prospective Studies; D019736:Prostheses and Implants; D019919:Prosthesis Implantation / Q000009:adverse effects / Q000379:methods*; D054140:Refractive Surgical Procedures; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology
chemical_list: D001672:Biocompatible Materials; D019904:Polymethyl Methacrylate