title: Corneal asphericity and spherical aberration after refractive surgery.
abstract: OBJECTIVE
  To evaluate changes in corneal asphericity (Q) and spherical aberrations after refractive surgery using Scheimpflug imaging.
  
  
  METHODS
  University of California, San Diego, Shiley Eye Center, La Jolla, California, USA.
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  After wavefront-guided laser in situ keratomileusis, patients within ± 0.50 diopter of plano and with an uncorrected distance visual acuity of at least 20/20 were evaluated. The Q values and corneal spherical aberration Zernike values were obtained using Scheimpflug imaging preoperatively and 1 to 3 months postoperatively.
  
  
  RESULTS
  The study enrolled 177 myopic eyes and 32 hyperopic eyes. The mean Q value was -0.28 ± 0.11 (SD) and -0.22 ± 0.15, respectively, preoperatively and +0.35 ± 0.44 and -0.64 ± 0.31, respectively, postoperatively. The asphericity change was highly correlated with preoperative spherical equivalent (r(2) = 0.81; P ≤ .001). The mean corneal spherical aberration was +0.21 ± 0.08 μm in myopic eyes and +0.36 ± 0.11 μm in hyperopic eyes preoperatively and +0.36 ± 0.17 μm and 0.00 ± 0.29 μm, respectively, postoperatively. The corneal spherical aberration changes were correlated with the amount of preoperative refractive error (r(2) = 0.34; P < .001). There was a tendency for Q values and spherical aberrations to become more positive after myopic ablation and more negative after hyperopic ablation.
  
  
  CONCLUSIONS
  Myopic and hyperopic corrections induced changes in the Q value and spherical aberrations in opposite directions (ie, positive and negative, respectively). The changes depended on the magnitude of the refractive correction.
  
  
  BACKGROUND
  No author has a financial or proprietary interest in any material or method mentioned.
authors: Shiley Eye Center, University of California San Diego, La Jolla, California, USA.
authors: Katia M
authors: KM
authors: Bottos
authors: Mauro T
authors: MT
authors: Leite
authors: Marichelle
authors: M
authors: Aventura-Isidro
authors: Jennifer
authors: J
authors: Bernabe-Ko
authors: Noppamas
authors: N
authors: Wongpitoonpiya
authors: Nikki Heidi
authors: NH
authors: Ong-Camara
authors: Tracy L
authors: TL
authors: Purcell
authors: David J
authors: DJ
authors: Schanzlin