title: Intracorneal ring segments for iatrogenic keratectasia after laser in situ keratomileusis or photorefractive keratectomy.
abstract: OBJECTIVE
  Intrastromal corneal ring segments (Intacs) were inserted in four eyes with iatrogenic keratectasia, 12 to 44 months after laser in situ keratomileusis (LASIK) in two patients and photorefractive keratectomy (PRK) in two patients, in order to avoid penetrating keratoplasty and to improve quality of vision.
  
  
  METHODS
  A modified asymmetrical Intacs micro-thin prescription inserts implantation technique was used in three eyes where a 1.0-mm temporal incision and a superior-inferior dissection were performed. A thicker segment was implanted in the lower stromal channel and a thinner one was placed in the superior channel. In the fourth eye, because of the severity of the corneal bulging after PRK, two 5.0-mm optical zone symmetrical Ferrara Ring segments were implanted.
  
  
  RESULTS
  Ten months after surgery, all eyes experienced a significant improvement of uncorrected and best spectacle-corrected visual acuity. The topographical indices showed an overall surface regularization with increased corneal uniformity and potential corneal visual acuity. No intraoperative or postoperative complications occurred.
  
  
  CONCLUSIONS
  Asymmetrical or symmetrical corneal ring segment implantation in eyes with keratectasia after LASIK or PRK resulted in safe, fairly predictable corneal regularization, with significant improvement of aided and unaided vision. In the short term, these techniques seem to be helpful in reducing the progression of corneal ectasia after excimer laser surgery, delaying or avoiding the need of penetrating keratoplasty.
mesh_terms: D000328:Adult; D003315:Cornea / Q000473:pathology*; D003319:Corneal Stroma / Q000601:surgery; D019781:Corneal Topography; D004108:Dilatation, Pathologic; D005260:Female; D006801:Humans; D007049:Iatrogenic Disease; D007640:Keratoconus / Q000209:etiology / Q000601:surgery*; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects*; D054018:Lasers, Excimer; D008297:Male; D018903:Photorefractive Keratectomy / Q000009:adverse effects*; D019904:Polymethyl Methacrylate; D019736:Prostheses and Implants; D019919:Prosthesis Implantation / Q000379:methods*; D012029:Refraction, Ocular; D012086:Reoperation; D014792:Visual Acuity
chemical_list: D019904:Polymethyl Methacrylate