title: Comparison of two types of visual quality analyzer for the measurement of high order aberrations.
abstract: OBJECTIVE
  To compare the difference and agreement of KR-1W and iTrace for measurement of high order aberrations.
  
  
  METHODS
  KR-1W and iTrace were respectively used in a group of healthy people (40 volunteers, 32 eyes) to measure the high order aberration (HOA) of corneal, internal and total ocular. The clinical difference and agreement of two instruments were respectively evaluated by paired-samples t-test and Bland-Altman analysis.
  
  
  RESULTS
  The paired-samples t-test showed that the corneal HOA measured by the two instruments had no statistical differences (P>0.05); but the internal and total ocular HOA had significant statistical differences (P<0.05), and the mean results measured by iTrace were higher than that of KR-1W. However, Bland-Altman analysis revealed that the HOA of corneal and internal were all in 95% limits of agreement; and just one point of total ocular HOA was beyond the 95% limits of agreement.
  
  
  CONCLUSIONS
  KR-1W and iTrace were consistent well in the measurement of corneal, internal and total ocular HOA, especially for the cornea.
authors.affiliation: Department of Cataract, Tianjin Medical University Eye Hospital, Tianjin 300384, China; North China University of Science and Technology, Tangshan 063000, Hebei Province, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Hao
authors.affiliation: Tangshan Gongren Hospital, Tangshan 063000, HeBei, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Cataract, Tianjin Medical University Eye Hospital, Tianjin 300384, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Tian
authors.affiliation: Department of Cataract, Tianjin Medical University Eye Hospital, Tianjin 300384, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
keywords: KR-1W; agreement; difference; high order aberration; iTrace