title: Corneal ectasia after LASIK despite low preoperative risk: tomographic and biomechanical findings in the unoperated, stable, fellow eye.
abstract: OBJECTIVE
  To report a case of progressive corneal ectasia after LASIK with no detectable preoperative risk factors and to present three-dimensional corneal tomographic and biomechanical findings on the contralateral unoperated eye that would be considered low risk for ectasia and thereby a good LASIK candidate based on the Randleman Ectasia Risk Score System (ERSS).
  
  
  METHODS
  A case report, literature review, and description of novel screening criteria based on Pentacam (Oculus Optikgeräte GmbH) corneal tomography are presented as well as Ocular Response Analyzer (ORA, Reichert Instruments) corneal biomechanical analysis.
  
  
  RESULTS
  Progressive corneal ectasia after LASIK of the operated left eye was confirmed by corneal topography. Scheimpflug imaging identified a meniscus-shaped LASIK flap with a central thickness of 165 μm and residual stromal bed thickness of 280 μm. Randleman ERSS score was 2 for the ectatic eye before LASIK and 1 for the current status of the unoperated eye, which remained stable with normal topography and no change in refraction for >5 years. Low corneal hysteresis (8.6 mmHg) and corneal resistance factor (7.5 mmHg) were found in the unoperated, nonectatic eye, along with a suspicious waveform sign of a second rebounded peak after second applanation. Pentacam average pachymetric progression was 1.09 (normal is <1.15); the Belin-Ambrósio overall deviation index was 1.99 (normal is <1.9).
  
  
  CONCLUSIONS
  Three-dimensional corneal tomographic and ORA biomechanical measurements provide additional information that may help identify individuals at high risk for naturally occurring or iatrogenic corneal ectasia.
authors.affiliation: Instituto de Olhos Renato Ambrosio, Rio de Janeiro, Brazil. renatoambrosiojr@terra.com.br
authors.forename: Renato
authors.initials: R
authors.lastname: Ambrósio
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Dawson
authors.forename: Marcella
authors.initials: M
authors.lastname: Salomão
authors.forename: Frederico P
authors.initials: FP
authors.lastname: Guerra
authors.forename: Ana Laura C
authors.initials: AL
authors.lastname: Caiado
authors.forename: Michael W
authors.initials: MW
authors.lastname: Belin
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D003316:Corneal Diseases / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D019781:Corneal Topography; D004108:Dilatation, Pathologic / Q000209:etiology; D018450:Disease Progression; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects*