title: Efficacy of single or paired intrastromal corneal ring segment implantation combined with collagen crosslinking in keratoconus.
abstract: OBJECTIVE
  To evaluate the efficacy of single or paired intrastromal corneal ring segments (ICRS) combined with ultraviolet-A and riboflavin collagen crosslinking (CXL) in patients with keratoconus.
  
  
  METHODS
  Cornea Unit, Toronto Western Hospital, Toronto, Ontario, Canada.
  
  
  METHODS
  Retrospective comparative case series.
  
  
  METHODS
  Consecutive patients with keratoconus had femtosecond laser-assisted ICRS implantation combined with same-day CXL between 2008 and 2011. The main outcome measures included improvement in visual acuity, subjective refractive error, keratometry values, and total higher-order aberration (HOA).
  
  
  RESULTS
  Eighty-five eyes of 74 patients with keratoconus (paired ICRS: 47 eyes of 40 patients; single ICRS: 38 eyes of 34 patients) were included in the study. The uncorrected distance visual acuity was significantly improved after single ICRS (3.4 lines; P=.04) and paired ICRS (2.7 lines; P=.01) implantation combined with CXL, while corrected distance visual acuity (CDVA) remained stable. The single and paired ICRS groups had a significant reduction in mean cylinder at 1 year (single ICRS: -3.84 diopters [D] ± 1.72 [SD] versus -2.19 ± 1.54 D, P=.02; paired ICRS: -3.91 ± 1.45 D versus -2.96 ± 1.92 D) (P=.02). There was no significant difference in total HOAs. Single ICRS implantation and paired ICRS implantation with CXL were equivalent in all refractive parameters. No patient lost lines of CDVA.
  
  
  CONCLUSIONS
  As determined by corneal topography, implantation of single or paired ICRS combined with same-day CXL was safe and effective in patients with keratoconus.
authors.affiliation: Yonge Eglinton Laser Eye Centre and the Department of Ophthalmology, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada. sonia.y@gmail.com
authors.forename: Sonia N
authors.initials: SN
authors.lastname: Yeung
authors.forename: Judy Y F
authors.initials: JY
authors.lastname: Ku
authors.forename: Alejandro
authors.initials: A
authors.lastname: Lichtinger
authors.forename: Stephanie A W
authors.initials: SA
authors.lastname: Low
authors.forename: Peter
authors.initials: P
authors.lastname: Kim
authors.forename: David S
authors.initials: DS
authors.lastname: Rootman
mesh_terms: D000328:Adult; D003094:Collagen / Q000378:metabolism*; D003131:Combined Modality Therapy; D003319:Corneal Stroma / Q000378:metabolism / Q000601:surgery*; D019781:Corneal Topography; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000188:drug therapy / Q000378:metabolism / Q000601:surgery / Q000628:therapy*; D008297:Male; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use; D011379:Prognosis; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D012189:Retrospective Studies; D012256:Riboflavin / Q000627:therapeutic use; D014466:Ultraviolet Rays; D014792:Visual Acuity / Q000502:physiology
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin