title: Short-term corneal changes with gas-permeable contact lens wear in keratoconus subjects: a comparison of two fitting approaches.
abstract: OBJECTIVE
  To evaluate changes in anterior corneal topography and higher-order aberrations (HOA) after 14-days of rigid gas-permeable (RGP) contact lens (CL) wear in keratoconus subjects comparing two different fitting approaches.
  
  
  METHODS
  Thirty-one keratoconus subjects (50 eyes) without previous history of CL wear were recruited for the study. Subjects were randomly fitted to either an apical-touch or three-point-touch fitting approach. The lens' back optic zone radius (BOZR) was 0.4mm and 0.1mm flatter than the first definite apical clearance lens, respectively. Differences between the baseline and post-CL wear for steepest, flattest and average corneal power (ACP) readings, central corneal astigmatism (CCA), maximum tangential curvature (KTag), anterior corneal surface asphericity, anterior corneal surface HOA and thinnest corneal thickness measured with Pentacam were compared.
  
  
  RESULTS
  A statistically significant flattening was found over time on the flattest and steepest simulated keratometry and ACP in apical-touch group (all p<0.01). A statistically significant reduction in KTag was found in both groups after contact lens wear (all p<0.05). Significant reduction was found over time in CCA (p=0.001) and anterior corneal asphericity in both groups (p<0.001). Thickness at the thinnest corneal point increased significantly after CL wear (p<0.0001). Coma-like and total HOA root mean square (RMS) error were significantly reduced following CL wearing in both fitting approaches (all p<0.05).
  
  
  CONCLUSIONS
  Short-term rigid gas-permeable CL wear flattens the anterior cornea, increases the thinnest corneal thickness and reduces anterior surface HOA in keratoconus subjects. Apical-touch was associated with greater corneal flattening in comparison to three-point-touch lens wear.
authors.affiliation: MGR Doctores, Madrid, Spain. Electronic address: mrjlentes@gmail.com.
authors.forename: Miguel
authors.initials: M
authors.lastname: Romero-Jiménez
authors.affiliation: Menicon Co. Ltd., Madrid, Spain.
authors.forename: Jacinto
authors.initials: J
authors.lastname: Santodomingo-Rubido
authors.affiliation: Pontificia Universidad Católica de Valparaíso, Chile.
authors.forename: Patricia
authors.initials: P
authors.lastname: Flores-Rodríguez
authors.affiliation: Clinical & Experimental Optometry Research Lab, Center of Physics, University of Minho, Braga, Portugal.
authors.forename: Jose-Manuel
authors.initials: JM
authors.lastname: González-Méijome
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001251:Astigmatism / Q000209:etiology / Q000473:pathology; D003261:Contact Lenses / Q000009:adverse effects*; D003262:Contact Lenses, Extended-Wear / Q000009:adverse effects*; D019781:Corneal Topography; D057108:Corneal Wavefront Aberration / Q000209:etiology* / Q000473:pathology; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000628:therapy*; D008297:Male; D017755:Prosthesis Fitting / Q000379:methods*; D055815:Young Adult
keywords: Contact lenses; Cornea; Córnea; Keratoconus; Lentes de contacto; Queratocono