title: Repeatability and reproducibility of biometry and keratometry measurements using a noncontact optical low-coherence reflectometer and keratometer.
abstract: OBJECTIVE
  To evaluate the repeatability, reproducibility, or both of the biometry and keratometry measurements obtained by a new optical low-coherence reflectometer and keratometer (Lenstar LS 900, version 1.10; Haag-Streit).
  
  
  METHODS
  Prospective, comparative, observational study.
  
  
  METHODS
  
  
  
  METHODS
  Private practice, Lynwood, California, and Santa Monica, California.
  
  
  METHODS
  The measurements of the second eye to be operated on of 37 patients between October 2010 and January 2011 were analyzed.
  
  
  METHODS
  The axial length, central corneal thickness, aqueous depth, anterior chamber depth, crystalline lens thickness, white-to-white corneal diameter, as well as the keratometric readings at the flattest meridian, the steepest meridian, the average K, the amount of astigmatism, and the minus astigmatic cylinder axis were measured before surgery on the patient's first eye and were repeated 1 month later before the second eye surgery. main outcome measures: The repeatability and reproducibility of the biometry and keratometry measurements.
  
  
  RESULTS
  Intrasession repeatability and intersession reproducibility were excellent with a very low coefficient of variation and high interclass correlation coefficients for all measured parameters. Bland-Altman plots show good correlation for axial length measurements (95% limits of agreement ranging from -0.056 to +0.04 mm), anterior chamber depth (-0.22 to +0.18 mm), crystalline lens thickness (-0.21 to +0.27 mm), corneal diameter (-0.28 to +0.24 mm), average keratometric readings (-0.56 to +0.47 diopters), and amount of astigmatism (-0.58 to +0.40 diopters).
  
  
  CONCLUSIONS
  The precision of the measurements obtained by the new optical reflectometer and keratometer is extremely high.
authors: Department of Ophthalmology, The Keck School of Medicine, University of Southern California, Los Angeles, California, USA. jshammas@shammaseye.com
authors: H John
authors: HJ
authors: Shammas
authors: Kenneth J
authors: KJ
authors: Hoffer
mesh_terms: D000867:Anterior Chamber / Q000033:anatomy & histology*; D058452:Axial Length, Eye; D001699:Biometry / Q000379:methods*; D003315:Cornea / Q000033:anatomy & histology*; D019781:Corneal Topography / Q000379:methods*; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation; D006801:Humans; D007368:Interferometry; D008027:Light; D011446:Prospective Studies; D015203:Reproducibility of Results