title: [The relationship between corneal astigmatism with a vector-based method and whole eye second order wavefront aberrations].
abstract: OBJECTIVE
  To investigate the relationship between corneal astigmatism and second order wavefront aberration in myopic eyes.
  
  
  METHODS
  The corneal astigmatism and the whole eye wavefront aberrations of both eyes of 246 subjects were measured using the Humphrey corneal topography and the WASCA wavefront analyzer. According to axial of the corneal astigmatism, the subjects were divided into five groups (WR(0), WR(180), AR, OA(45) and OA(135)). The corneal astigmatism was decomposed into J(45) and J(0) with a Vector-based method, and correlated with the 2nd order Zernike aberrations (C(3) and C(5)).
  
  
  RESULTS
  The mean corneal astigmatisms for the five groups were -1.34 D x 6.87 degrees, -1.03 D x 23.15 degrees, -0.48 D x 89.55 degrees, -0.91 D x 156.87 degrees and -1.02 D x 176.74 degrees respectively. Most of the corneal J(45) and J(0) components were correlated significantly with the C(3) and the C(5) aberrations in the whole eye. While the correlation coefficients (R(2)) between the J(45) and the C(3) were 0.138, 0.119, 0.090, 0.526 and 0.501, the R(2) between the J(0) and the C(5) were 0.711, 0.736, 0.864, 0.866 and 0.785 for the five groups respectively.
  
  
  CONCLUSIONS
  The corneal astigmatism plays an important role in determining the 2nd order wavefront aberration in the whole eye, and the combination processes between the corneal and internal astigmatism (compensation and/or addition) change with the axial of the corneal astigmatism.
authors.affiliation: School of Optometry & Ophthalmology, Wenzhou 325027, China.
authors.forename: Jiang-xiu
authors.initials: JX
authors.lastname: Wu
authors.forename: Fan
authors.initials: F
authors.lastname: Lü
authors.forename: Ji-cang
authors.initials: JC
authors.lastname: He
authors.forename: Liang
authors.initials: L
authors.lastname: Hu
authors.forename: Ye-yu
authors.initials: YY
authors.lastname: Shen
authors.forename: Shi-hao
authors.initials: SH
authors.lastname: Chen
authors.forename: Chen-chen
authors.initials: CC
authors.lastname: Xu
authors.forename: Jia
authors.initials: J
authors.lastname: Qu
mesh_terms: D000293:Adolescent; D000328:Adult; D001251:Astigmatism / Q000503:physiopathology*; D003315:Cornea / Q000503:physiopathology*; D019781:Corneal Topography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D009216:Myopia / Q000503:physiopathology; D012029:Refraction, Ocular / Q000502:physiology