title: Outcome analysis of intracorneal ring segments for the treatment of keratoconus based on visual, refractive, and aberrometric impairment.
abstract: OBJECTIVE
  To analyze the outcomes of intracorneal ring segment (ICRS) implantation for the treatment of keratoconus based on preoperative visual impairment.
  
  
  METHODS
  Multicenter, retrospective, nonrandomized study.
  
  
  METHODS
  A total of 611 eyes of 361 keratoconic patients were evaluated. Subjects were classified according to their preoperative corrected distance visual acuity (CDVA) into 5 different groups: grade I, CDVA of 0.90 or better; grade II, CDVA equal to or better than 0.60 and worse than 0.90; grade III, CDVA equal to or better than 0.40 and worse than 0.60; grade IV, CDVA equal to or better than 0.20 and worse than 0.40; and grade plus, CDVA worse than 0.20. Success and failure indices were defined based on visual, refractive, corneal topographic, and aberrometric data and evaluated in each group 6 months after ICRS implantation.
  
  
  RESULTS
  Significant improvement after the procedure was observed regarding uncorrected distance visual acuity in all grades (P < .05). CDVA significantly decreased in grade I (P < .01) but significantly increased in all other grades (P < .05). A total of 37.9% of patients with preoperative CDVA 0.6 or better gained 1 or more lines of CDVA, whereas 82.8% of patients with preoperative CDVA 0.4 or worse gained 1 or more lines of CDVA (P < .01). Spherical equivalent and keratometry readings showed a significant reduction in all grades (P ≤ .02). Corneal higher-order aberrations did not change after the procedure (P ≥ .05).
  
  
  CONCLUSIONS
  Based on preoperative visual impairment, ICRS implantation provides significantly better results in patients with a severe form of the disease. A notable loss of CDVA lines can be expected in patients with a milder form of keratoconus.
authors.affiliation: Keratoconus Unit, Vissum Corporation, Alicante, Spain.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Vega-Estrada
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Alio
authors.forename: Luis F
authors.initials: LF
authors.lastname: Brenner
authors.forename: Jaime
authors.initials: J
authors.lastname: Javaloy
authors.forename: Ana Belen
authors.initials: AB
authors.lastname: Plaza Puche
authors.forename: Rafael I
authors.initials: RI
authors.lastname: Barraquer
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Teus
authors.forename: Joaquim
authors.initials: J
authors.lastname: Murta
authors.forename: Jorge
authors.initials: J
authors.lastname: Henriques
authors.forename: Antonio
authors.initials: A
authors.lastname: Uceda-Montanes
mesh_terms: D057128:Aberrometry; D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D003319:Corneal Stroma / Q000601:surgery*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D012029:Refraction, Ocular / Q000502:physiology*; D012189:Retrospective Studies; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology*