title: Refractive and topographic effects of single-segment intrastromal corneal ring segments in eyes with moderate to severe keratoconus and inferior cones.
abstract: OBJECTIVE
  To evaluate the efficacy and safety of a single intrastromal corneal ring segment (ICRS) (450 μm Intacs SK) in moderate to severe keratoconic eyes with an inferiorly located cone and a noninvolved center.
  
  
  METHODS
  Ophthalmology Department, American University of Beirut Medical Center, Beirut, Lebanon.
  
  
  METHODS
  Retrospective case series.
  
  
  METHODS
  The uncorrected (UDVA) and corrected (CDVA) distance visual acuities, central and inferior maximum topographic keratometry (K) values, manifest cylinder, and spherical equivalent (SE) were recorded preoperatively and 1 week and 1, 3, and 6 months postoperatively.
  
  
  RESULTS
  Thirty eyes were studied. The mean age was 29.6 years ± 8.0 (SD). The mean preoperative UDVA and CDVA were 20/86 and 20/42, respectively. The mean center K was 49.14 ± 4.39 diopters (D); the mean maximum K, 56.78 ± 6.02 D; and the mean center K - maximum K, -7.45 ± 5.61 D. The mean SE and cylinder were -2.24 ± 2.32 D and -4.33 ± 1.43 D, respectively, with sphere ranging from +2.00 to -18.00 D. At 6 months, the UDVA improved to 20/32. The mean SE was -1.02 ± 2.04 D (P = .0330); the mean cylinder, -1.67 ± 1.00 D (P < .00); and the mean center K - maximum K, -4.92 ± 4.36 D (P < .05). The CDVA improved more than 2 lines; no eye lost any lines. Topographic indices improved in all eyes.
  
  
  CONCLUSIONS
  Single ICRS implantation in eyes with moderate to severe keratoconus and inferiorly located cones was safe and effective. The development of a nomogram relying more on topographic data is suggested.
  
  
  BACKGROUND
  No author has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: From the Ophthalmic Consultants of Beirut (Fahd, Nasser), Metn, and the Department of Ophthalmology (Fahd, Alameddine, Awwad), American University of Beirut Medical Center, Beirut, Lebanon.
authors.forename: Daoud C
authors.initials: DC
authors.lastname: Fahd
authors.affiliation: From the Ophthalmic Consultants of Beirut (Fahd, Nasser), Metn, and the Department of Ophthalmology (Fahd, Alameddine, Awwad), American University of Beirut Medical Center, Beirut, Lebanon.
authors.forename: Ramzi M
authors.initials: RM
authors.lastname: Alameddine
authors.affiliation: From the Ophthalmic Consultants of Beirut (Fahd, Nasser), Metn, and the Department of Ophthalmology (Fahd, Alameddine, Awwad), American University of Beirut Medical Center, Beirut, Lebanon.
authors.forename: Marc
authors.initials: M
authors.lastname: Nasser
authors.affiliation: From the Ophthalmic Consultants of Beirut (Fahd, Nasser), Metn, and the Department of Ophthalmology (Fahd, Alameddine, Awwad), American University of Beirut Medical Center, Beirut, Lebanon. Electronic address: shady.awwad@aub.edu.lb.
authors.forename: Shady T
authors.initials: ST
authors.lastname: Awwad
mesh_terms: D000293:Adolescent; D000328:Adult; D003319:Corneal Stroma / Q000503:physiopathology / Q000601:surgery*; D019781:Corneal Topography; D057108:Corneal Wavefront Aberration / Q000503:physiopathology; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D019904:Polymethyl Methacrylate; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D012029:Refraction, Ocular / Q000502:physiology*; D012189:Retrospective Studies; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult
chemical_list: D019904:Polymethyl Methacrylate