title: Long-term follow-up of ultrathin corneas after surface retreatment with phototherapeutic keratectomy.
abstract: OBJECTIVE
  To evaluate visual acuity and long-term stability after phototherapeutic keratectomy (PTK) in patients with corneal thickness less than 400 microm and cornea-related vision problems.
  
  
  METHODS
  Department of Ophthalmology, Istituto Clinico Humanitas, Rozzano-Milan, Italy.
  
  
  METHODS
  This retrospective study comprised 48 eyes that had PTK for complications after photorefractive keratectomy that removed more than 200 microm of tissue. Phototherapeutic keratectomy was performed with the Nidek EC-5000 excimer laser with 10 Hz frequency, intraoperative topography, and masking fluid over an ablation diameter of 10.0 mm. The follow-up was 5 years. The mean preoperative best spectacle-corrected visual acuity (BSCVA) was 0.2 +/- 0.09 (SD) with -2.53 +/- 2.34 diopters (D), and the mean pachymetry was 390 +/- 38 microm. The efficacy parameters were pachymetry and visual acuity at 1 year and the stability parameters, optical refraction, corneal curvature (calculated as the mean curvature over the entire 3.0 mm and 5.0 mm central zones), and pachymetry from 1 to 5 years.
  
  
  RESULTS
  At 1 year, the mean BSCVA was 0.6 +/- 0.72 with -2.15 +/- 1.67 D and the mean pachymetry, 341 +/- 40 microm. At 5 years, the mean BSCVA was 0.7 +/- 0.15 with -2.33 +/- 1.12 D and the mean pachymetry, 339 +/- 48 microm. In all patients, there was an improvement of 4 or more Snellen lines. Statistical evaluation of refraction and corneal curvature values at 1 and 5 years indicated no statistically significant differences.
  
  
  CONCLUSIONS
  After PTK in eyes with ultrathin corneas, there was significant improvement in BSCVA and long-term stability of the optical refraction, corneal curvature, and pachymetry. In selected cases, 10.0 mm ablation zone PTK may be an alternative to penetrating keratoplasty, offering long-term corneal stability.
authors.affiliation: Department of Ophthalmology, Istituto Clinico Humanitas, Rozzano-Milan, Italy. pvinciguerra@vincieye.it
authors.forename: Paolo
authors.initials: P
authors.lastname: Vinciguerra
authors.forename: Maria Ingrid Torres
authors.initials: MI
authors.lastname: Munoz
authors.forename: Fabrizio I
authors.initials: FI
authors.lastname: Camesasca
authors.forename: Fabio
authors.initials: F
authors.lastname: Grizzi
authors.forename: Cynthia
authors.initials: C
authors.lastname: Roberts
mesh_terms: D000328:Adult; D000886:Anthropometry; D003315:Cornea / Q000033:anatomy & histology* / Q000502:physiology; D003316:Corneal Diseases / Q000503:physiopathology / Q000601:surgery*; D048988:Corneal Surgery, Laser / Q000379:methods*; D019781:Corneal Topography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015948:Keratoplasty, Penetrating; D008297:Male; D011183:Postoperative Complications; D012029:Refraction, Ocular / Q000502:physiology; D012086:Reoperation; D012189:Retrospective Studies; D016896:Treatment Outcome; D014786:Vision Disorders / Q000503:physiopathology / Q000601:surgery*; D014792:Visual Acuity / Q000502:physiology