title: Comparison of corneal astigmatism measurements of 2 optical biometer models for toric intraocular lens selection.
abstract: OBJECTIVE
  To compare corneal astigmatism measurements obtained using a new optical biometer (AL-Scan) and a standard biometer based on partial coherence interferometry (IOLMaster 500) for toric intraocular lens (IOL) selection.
  
  
  METHODS
  Siriraj Hospital, Mahidol University, Bangkok, Thailand.
  
  
  METHODS
  Prospective comparative study.
  
  
  METHODS
  Keratometry (K) readings were taken with the 2 biometers in eyes of cataract patients. The corneal astigmatism readings from the 2 devices were compared. The cylinder measurements were transformed into J0 and J45 vector components for analysis, and the devices' values were compared using the paired t test. Correlation coefficients were calculated. The Bland-Altman method was used to evaluate the agreement between the sets of measurements.
  
  
  RESULTS
  One hundred thirty-seven eyes (81 patients) were enrolled. The magnitude of astigmatism between the new biometer 2.4 mm zone and the standard biometer was similar (P = .19). There was a statistically significant difference between values from the new biometer 3.3 mm zone and the standard biometer (P < .05). There was good correlation in the overall magnitude of astigmatism between devices. There was a trend of low correlation toward the flat cornea (K <43.0 diopters [D]), low corneal cylinder (<1.0 D), and with-the-rule astigmatism. The IOL toricity calculated from both devices was similar.
  
  
  CONCLUSIONS
  Corneal astigmatism measurements with the 2 biometers were similar in magnitude, especially in 2.4 mm zone of the new biometer. There was no difference in the toric IOL selections between the devices.
  
  
  BACKGROUND
  No author has a financial or proprietary interest in any material or method mentioned.
authors: From the Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors: Sabong
authors: S
authors: Srivannaboon
authors: From the Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand. Electronic address: chareenun@gmail.com.
authors: Chareenun
authors: C
authors: Chirapapaisan
authors: From the Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors: Pratuangsri
authors: P
authors: Chonpimai
authors: From the Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors: Sunisa
authors: S
authors: Koodkaew
mesh_terms: D000368:Aged; D001251:Astigmatism / Q000175:diagnosis*; D001699:Biometry / Q000295:instrumentation*; D003315:Cornea / Q000473:pathology*; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D006801:Humans; D007910:Lenses, Intraocular; D008433:Mathematics; D055095:Optics and Photonics; D018918:Phacoemulsification; D011300:Preoperative Care; D011446:Prospective Studies; D015203:Reproducibility of Results