title: Femtosecond-assisted intrastromal corneal ring implantation for keratoconus treatment: a comparison with crosslinking combination.
abstract: OBJECTIVE
  To compare visual outcomes, corneal astigmatism, and keratometric readings in patients with keratoconus who underwent intrastromal corneal ring implantation (ICRSI) alone with those who underwent ICRSI combined with ultraviolet A riboflavin-mediated corneal collagen crosslinking (CXL).
  
  
  METHODS
  Pre- and post-operative best-corrected distance visual acuity (BCDVA), spherical error, cylindrical error, and mean keratometry were retrospectively compared over a period of 2 years in patients with keratoconus who underwent only ICRSI (group 1) versus those in patients who underwent combined ICRSI-CXL (group 2).
  
  
  RESULTS
  Thirty-two eyes of 31 patients were evaluated. CXL was performed in 10 cases (31%), and there were no complications or need for ring repositioning. BCDVA improved from 0.54 to 0.18 in the group 1 and from 0.56 to 0.17 in the group 2. Spherical and cylindrical errors and mean keratometry values significantly decreased in both groups. No patient postoperatively had visual acuity (VA) of less than 20/60 on refraction, and 78% exhibited VA better than or equal to 20/40 with spectacles (72% of group 1 and 90% of group 2). Improvement in the spherical equivalent (SE) value was observed in the group 1 (from -5.89 ± 3.37 preoperatively to -2.65 ± 2.65 postoperatively; p<0.05) and group 2 (from -6.91 ± 1.93 preoperatively to -2.11 ± 3.01 postoperatively; p<0.05).
  
  
  CONCLUSIONS
  Both techniques can be considered safe and effective in improving VA and refractive SE values, in decreasing the curvature of the cone apex in the topographical analysis, and in decreasing corrected diopters postoperatively in patients with keratoconus.
authors.affiliation: Anterior Segment Sector, Hospital de Olhos do Paraná, Curitiba, PR, Brazil.
authors.forename: Peter Alexander von Harbach
authors.initials: PA
authors.lastname: Ferenczy
authors.affiliation: Anterior Segment Sector, Hospital de Olhos do Paraná, Curitiba, PR, Brazil.
authors.forename: Maiara
authors.initials: M
authors.lastname: Dalcegio
authors.affiliation: Refractive Surgery Sector, Hospital de Olhos do Paraná, Curitiba, PR, Brazil.
authors.forename: Marcela
authors.initials: M
authors.lastname: Koehler
authors.affiliation: Refractive Surgery Sector, Hospital de Olhos do Paraná, Curitiba, PR, Brazil.
authors.forename: Thiago Silveira
authors.initials: TS
authors.lastname: Pereira
authors.affiliation: Hospital de Olhos do Paraná, Curitiba, PR, Brazil.
authors.forename: Hamilton
authors.initials: H
authors.lastname: Moreira
authors.affiliation: Contact Lens Sector, Hospital de Olhos do Paraná, Curitiba, PR, Brazil.
authors.forename: Moreira
authors.initials: M
authors.lastname: Luciane Bugmann
mesh_terms: D000293:Adolescent; D000328:Adult; D003094:Collagen / Q000627:therapeutic use; D003131:Combined Modality Therapy; D003319:Corneal Stroma / Q000601:surgery*; D048988:Corneal Surgery, Laser / Q000379:methods*; D019781:Corneal Topography; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D017319:Photosensitizing Agents / Q000627:therapeutic use; D019736:Prostheses and Implants; D019919:Prosthesis Implantation / Q000379:methods*; D012189:Retrospective Studies; D012256:Riboflavin / Q000627:therapeutic use; D018709:Statistics, Nonparametric; 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; D012256:Riboflavin