title: Analysis of results related to good and bad outcomes of Intacs implantation for keratoconus correction.
abstract: OBJECTIVE
  To evaluate factors influencing good and poor outcomes after intracorneal ring segment implantation to correct keratoconus.
  
  
  METHODS
  Instituto Oftalmológico de Alicante (Vissum Corporation), University of Miguel Hernandez, Alicante, Spain.
  
  
  METHODS
  A retrospective comparative study of the visual outcome, 25 eyes of 21 patients were implanted after intracorneal ring segments (Intacs, Addition Technology) as a method to correct keratoconus. Outcomes were evaluated 6 months after implantation based on the visual results. Group A comprised 20 eyes that gained 3 lines or more of best spectacle-corrected visual acuity (BSCVA) to correct keratoconus, and Group B comprised 5 eyes that lost 1 line of BSCVA.
  
  
  RESULTS
  In Group A, the preoperative mean BSCVA was 0.43 (20/50) and the postoperative mean BSCVA, 0.82 (20/20) (P< or =.0001). In Group B, the preoperative mean BSCVA was 0.36 (20/63) and the postoperative mean BSCVA, 0.24 (20/80) (P< or =.02). The preoperative mean sphere power was 3.90 diopters (D) greater in Group B than in Group A (P< or =.007); the mean spherical equivalent was 4.36 D greater (P< or =.007), and the mean K-reading was 6.91 D greater (P< or =.001). The postoperative reduction in spherical dioptric power was 2.11 D (P< or =.027) and the mean spherical equivalent, 2.81 D (P< or =.003), significant only in Group A. The reduction in mean central K-readings was 4.30 D (P< or =.0001) in Group A and 6.19 D (P< or =.014) in Group B. The correlation of the preoperative mean K value to the postoperative BSCVA was significant at the .01 level by the Pearson test (-0.67). In Group A, all eyes (100%) had a mean K-reading < or =53 D. In Group B, 4 eyes (80%) had a mean K-reading > or =55 D.
  
  
  CONCLUSIONS
  Intacs provided better results in visual acuity and corneal topography quality and significantly reduced the spherical equivalent in eyes with keratoconus with relatively low mean K values (< or =53 D) and a relatively low spherical equivalent. In advanced keratoconus (mean K-reading > or =55 D), poor results can be anticipated.
authors.affiliation: Instituto Oftalmológico de Alicante, Vissum (Department of Cornea and Refractive Surgery), Miguel Hernández University, Medical School, Alicante, Spain. jlalio@vissum.com
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Alió
authors.forename: Mohamed H
authors.initials: MH
authors.lastname: Shabayek
authors.forename: José I
authors.initials: JI
authors.lastname: Belda
authors.forename: Pablo
authors.initials: P
authors.lastname: Correas
authors.forename: Elio Diez
authors.initials: ED
authors.lastname: Feijoo
mesh_terms: D000328:Adult; D003319:Corneal Stroma / Q000503:physiopathology / Q000601:surgery*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D019736:Prostheses and Implants; D019919:Prosthesis Implantation / Q000379:methods*; D012189:Retrospective Studies; D014792:Visual Acuity / Q000502:physiology