title: Corneal aberrometric and refractive performance of 2 intrastromal corneal ring segment models in early and moderate ectatic disease.
abstract: OBJECTIVE
  To evaluate and compare visual, refractive, and corneal aberrometric outcomes after implantation of 2 types of intrastromal corneal ring segments (ICRS) in eyes with early to moderate ectatic disease.
  
  
  METHODS
  Vissum Corporation-Instituto Oftalmológico de Alicante, Alicante, Spain.
  
  
  METHODS
  This retrospective analysis comprised consecutive eyes with grade I or grade II corneal ectasia (keratoconus, pellucid marginal degeneration, ectasia after laser in situ keratomileusis) that had Intacs (Group I) or KeraRings (Group K) ICRS implantation using femtosecond technology. Visual, refractive, and corneal aberrometric outcomes were analyzed and compared between groups over a 6-month follow-up.
  
  
  RESULTS
  Group I had 17 eyes and Group K, 20 eyes. One month postoperatively, there was a statistically significant reduction in sphere in both groups (P<or=.02). At 6 months, there was a statistically significant reduction in manifest cylinder in Group K that was consistent with the significant reduction in corneal astigmatic aberration (both P = .04). The uncorrected distance visual acuity increased significantly in Group K (P = .04) but not in Group I; 41.18% of eyes in Group I and 52.94% in Group K gained 1 or more lines of corrected distance visual acuity. Both groups had significant corneal flattening (P<or=.02). At 1 month, the mean primary spherical aberration was -0.17 microm +/- 0.52 (SD) in Group I and 0.40 +/- 0.35 microm in Group K; the difference was statistically significant (P<.01).
  
  
  CONCLUSIONS
  Astigmatism correction in early to moderate ectatic corneas was more limited with the Intacs ICRS, which induced negative primary spherical aberration in the initial postoperative period.
  
  
  BACKGROUND
  No author has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: Vissum Corporation-Instituto Oftalmológico de Alicante, Departamento de Optica, Universidad de Alicante, Alicante, Spain.
authors.forename: David P
authors.initials: DP
authors.lastname: Piñero
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Alió
authors.forename: Bassam
authors.initials: B
authors.lastname: El Kady
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Pascual
mesh_terms: D057128:Aberrometry; D000293:Adolescent; D000328:Adult; D001251:Astigmatism / Q000503:physiopathology; D003315:Cornea / Q000502:physiology* / Q000601:surgery; D003316:Corneal Diseases / Q000503:physiopathology / Q000601:surgery*; D019781:Corneal Topography; D004108:Dilatation, Pathologic; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D012029:Refraction, Ocular / Q000502:physiology*; D012189:Retrospective Studies; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult