title: Higher order aberrations after keratoplasty for keratoconus.
abstract: OBJECTIVE
  To compare higher order aberrations (HOAs) caused by the anterior and posterior corneal surfaces after conventional penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK), and automated lamellar therapeutic keratoplasty (ALTK) in patients undergoing corneal transplantation for keratoconus (KC).
  
  
  METHODS
  This retrospective, observational, cross-sectional study included one eye of the following subjects: 40 patients with KC, 23 KC patients after PK, 17 KC patients after DALK, 18 KC patients after ALTK, and 38 healthy controls. All underwent imaging with a rotating Scheimpflug camera (at least 6 months after complete suture removal in grafted subjects) to assess the HOAs from the anterior and posterior corneal surfaces within the central 4-mm and 6-mm zones. The conversion of the corneal elevation profile into corneal wavefront data was performed using Zernike polynomials. Total and third- and fourth-order HOAs were considered. The root mean square of the Zernike vector magnitude, expressed in micrometers, was used. Differences among groups were assessed using the Kruskal-Wallis and Duncan multiple range tests. Statistical significance was defined as p < 0.05.
  
  
  RESULTS
  In both 4-mm and 6-mm central zones, the total HOAs from the anterior corneal surfaces were significantly lower in DALK than in ALTK and PK groups (p < 0.05). The total HOAs from the posterior corneal surface were comparable amongst postoperative groups (p > 0.05). The aberration components that were significantly greater included coma in the KC and ALTK eyes, trefoil and coma in the DALK eyes, and trefoil in the PK eyes.
  
  
  CONCLUSIONS
  The corneal anterior surface optical quality appeared significantly better after DALK than after ALTK and PK.
authors: Department of Ophthalmology, S. Maria della Misercordia Hospital, Udine, Italy.
authors: Maria Letizia
authors: ML
authors: Salvetat
authors: Paolo
authors: P
authors: Brusini
authors: Emilio
authors: E
authors: Pedrotti
authors: Marco
authors: M
authors: Zeppieri
authors: Flavia
authors: F
authors: Miani
authors: Mattia
authors: M
authors: Marcigaglia
authors: Mattia
authors: M
authors: Passilongo
authors: Giorgio
authors: G
authors: Marchini
mesh_terms: D000328:Adult; D003315:Cornea / Q000473:pathology*; D019781:Corneal Topography; D057108:Corneal Wavefront Aberration / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D003430:Cross-Sectional Studies; D006801:Humans; D015994:Incidence; D007558:Italy / Q000453:epidemiology; D007640:Keratoconus / Q000601:surgery; D015948:Keratoplasty, Penetrating; D008875:Middle Aged; D011183:Postoperative Complications; D012189:Retrospective Studies; D014792:Visual Acuity