title: Intrastromal corneal ring segment implantation by femtosecond laser for the correction of residual astigmatism after penetrating keratoplasty.
abstract: OBJECTIVE
  To evaluate the safety and efficacy of intracorneal ring segments (ICRSs) aided by femtosecond (FS) laser for the correction of residual astigmatism after penetrating keratoplasty (PKP).
  
  
  METHODS
  This retrospective noncomparative study comprised 14 eyes of 14 patients with high astigmatism after PKP who had ICRS implantation by femtosecond laser. The study evaluated uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive astigmatism, and corneal maximum curvature.
  
  
  RESULTS
  The CDVA postoperatively improved after 3 months (P < 0.001) and 6 months (P < 0.001) compared with CDVA preoperatively. The CDVA at 3 months was similar to that at 6 months (P > 0.999) as well as the UDVA (P = 0.276). The preoperative astigmatism was higher than that after surgery (P = 0.001). The preoperative maximum curvature was higher than that of the postoperative maximum curvature (P < 0.001).
  
  
  CONCLUSIONS
  The implantation of ICRSs using the femtosecond laser for residual astigmatism post-PKP was safe and showed satisfactory results. It reduced refractive astigmatism and maximum corneal curvature and improved UDVA and CDVA.
authors.affiliation: Department of Ophthalmology, Sorocaba Eye Bank, Sorocaba, São Paulo, Brazil. tatianaprazeres@hotmail.com
authors.forename: Tatiana Moura Bastos
authors.initials: TM
authors.lastname: Prazeres
authors.forename: Allan Cezar da Luz
authors.initials: AC
authors.lastname: Souza
authors.forename: Nicolas Cesário
authors.initials: NC
authors.lastname: Pereira
authors.forename: Fábio
authors.initials: F
authors.lastname: Ursulino
authors.forename: Leon
authors.initials: L
authors.lastname: Grupenmacher
authors.forename: Luciene Barbosa
authors.initials: LB
authors.lastname: de Souza
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D003319:Corneal Stroma / Q000601:surgery*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D015948:Keratoplasty, Penetrating / Q000009:adverse effects*; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D011183:Postoperative Complications; D019736:Prostheses and Implants; D019919:Prosthesis Implantation / Q000379:methods*; D012189:Retrospective Studies; D014792:Visual Acuity / Q000502:physiology