title: Corneal collagen cross-linking before Ferrara intrastromal corneal ring implantation for the treatment of progressive keratoconus.
abstract: OBJECTIVE
  To evaluate the safety, efficacy, and stability of sequential corneal collagen cross-linking (CXL) and Ferrara intrastromal corneal ring segment (FR) implantation in selected patients with progressive keratoconus.
  
  
  METHODS
  This prospective study involved 9 eyes with progressive keratoconus and a preoperative cylinder value equal to or greater than 5 diopters (D) diagnosed between June 2007 and October 2008. Preoperative and postoperative (6 months after the CXL procedure and 6 months after the FR implantation) biomicroscopy examinations, distance uncorrected and best-corrected visual acuities, refractive error, and topographic maps were evaluated and compared.
  
  
  RESULTS
  Mean uncorrected visual acuity was 1.11 logarithm of the minimal angle of resolution (logMAR) preoperatively and 0.75 logMAR at 6 months after CXL (P = 0.03) and 0.23 logMAR at 6 months after FR implantation (P < 0.001). Mean best-corrected visual acuity was 0.26 logMAR preoperatively and 0.24 logMAR at 6 months after CXL (P = 0.87) and 0.12 logMAR at 6 months after FR (P = 0.05). Statistically significant reductions in the mean spherical equivalent (4.38 D; P < 0.001) and mean maximum (5.58 D; P < 0.001) and minimum (4.17 D; P < 0.001) keratometry values were present at 6 months after FR.
  
  
  CONCLUSIONS
  FR implantation after CXL is a safe and efficacious treatment option for managing selected patients with progressive keratoconus. Good results in terms of visual acuity, postoperative residual refractive error, and keratometry values were obtained. Longer follow-up would be valuable to confirm the stability of these results.
authors.affiliation: Research Department, Instituto de Ojos Oftalmosalud, Lima, Peru. mariale_1610@hotmail.com
authors.forename: Maria A
authors.initials: MA
authors.lastname: Henriquez
authors.forename: Luis
authors.initials: L
authors.lastname: Izquierdo
authors.forename: Cesar
authors.initials: C
authors.lastname: Bernilla
authors.forename: Martin
authors.initials: M
authors.lastname: McCarthy
mesh_terms: D000293:Adolescent; 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*; D018450:Disease Progression; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000188:drug therapy / Q000601:surgery / Q000628:therapy*; D008297:Male; D017319:Photosensitizing Agents / Q000627:therapeutic use; D019904:Polymethyl Methacrylate; D011446:Prospective Studies; D019919:Prosthesis Implantation; D012256:Riboflavin / Q000627:therapeutic use; D016896:Treatment Outcome; D014466:Ultraviolet Rays; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D019904:Polymethyl Methacrylate; D012256:Riboflavin