title: Influence of posterior corneal astigmatism on postoperative refractive astigmatism in pseudophakic eyes after cataract surgery.
abstract: BACKGROUND
  To examine the influence of posterior corneal astigmatism on postoperative refractive astigmatism in pseudophakic eyes after cataract surgery.
  
  
  METHODS
  The study enrolled 64 pseudophakic eyes of 50 patients (71.8 ± 9.9 years old, mean ± standard deviation) who had undergone phacoemulsification with non-toric IOL implantation. Refractive astigmatism was measured using an auto ref-keratometer with a 0.01- diopter (D) scale. Two types of corneal astigmatism were calculated using anterior segment optical coherence tomography; keratometric and total corneal astigmatism. Keratometric astigmatism was obtained based on anterior corneal curvature alone and total corneal astigmatism was calculated using both anterior and posterior corneal curvatures. The difference between refractive and corneal astigmatism was computed as the vector difference using 1) refractive and keratometric astigmatism and 2) refractive and total corneal astigmatism.
  
  
  RESULTS
  The mean refractive, keratometric, and total corneal astigmatism was 0.92 ± 0.48 D, 0.87 ± 0.44 D, and 0.94 ± 0.46 D, respectively. The difference between refractive and keratometric astigmatism (0.70 ± 0.40 D, mean vector of 0.30 D axis 164°) was significantly larger than the difference between refractive and total corneal astigmatism (0.63 ± 0.38 D, mean vector of 0.12 D axis 137°) (P = .019).
  
  
  CONCLUSIONS
  The difference between refractive and total corneal astigmatism, calculated using both anterior and posterior corneal curvatures, was significantly smaller than the difference between refractive and keratometric astigmatism using anterior corneal astigmatism alone, implying that the latter overestimates the true postoperative refractive astigmatism and can cause cylindrical inaccuracy after cataract surgery.
authors.affiliation: Department of Ophthalmology, University of Tsukuba Hospital, 2-1-1 Amakubo, Tsukuba, Ibaraki, 305-8576, Japan. konkonhotaru@yahoo.co.jp.|Hitachi General Hospital, 2-1-1 Jonancho, Hitachi, Ibaraki, 317-0077, Japan. konkonhotaru@yahoo.co.jp.|Seinan Medical Center hospital, 2190 Sakaimachi, Sashimagun, Ibaraki, 306-0433, Japan. konkonhotaru@yahoo.co.jp.
authors.forename: Maki
authors.initials: M
authors.lastname: Sano
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, University of Tsukuba, 2-1-1 Amakubo, Tsukuba, Ibaraki, 305-8576, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Hiraoka
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, University of Tsukuba, 2-1-1 Amakubo, Tsukuba, Ibaraki, 305-8576, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Ueno
authors.affiliation: Hitachi General Hospital, 2-1-1 Jonancho, Hitachi, Ibaraki, 317-0077, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Itagaki
authors.affiliation: Seinan Medical Center hospital, 2190 Sakaimachi, Sashimagun, Ibaraki, 306-0433, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Ogami
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, University of Tsukuba, 2-1-1 Amakubo, Tsukuba, Ibaraki, 305-8576, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Oshika
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000175:diagnosis / Q000503:physiopathology*; D003315:Cornea / Q000502:physiology / Q000601:surgery*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular; D008297:Male; D008875:Middle Aged; D018918:Phacoemulsification; D057972:Posterior Eye Segment / Q000503:physiopathology*; D012029:Refraction, Ocular / Q000502:physiology*; D041623:Tomography, Optical Coherence
keywords: Cataract surgery; Posterior astigmatism; Toric intraocular lens