title: Comparison of 2 laser instruments for measuring axial length.
abstract: OBJECTIVE
  To compare axial length (AL), anterior chamber depth (ACD), and keratometric (K) measurements of 2 laser biometers.
  
  
  METHODS
  Private practices, Lynwood and Santa Monica, California, USA.
  
  
  METHODS
  In this prospective comparative observational study of eyes with cataract and eyes with a clear lens, AL, ACD, and K measurements were performed using an IOLMaster biometer, which uses partial coherence interferometry (PCI), and a Lenstar LS 900 biometer, which uses optical low-coherence reflectometry (OLCR). Intraocular lens (IOL) power calculation was performed using the Haigis formula. The IOL prediction error was calculated for each eye.
  
  
  RESULTS
  The study evaluated 50 eyes with cataract and 50 eyes with a clear lens. There was a good correlation between AL, ACD, and K measurements in the cataractous eyes (r = 0.9993, 0.9667, and 0.9959, respectively) and in eyes with a clear lens (r = 0.9995, 0.8211, and 0.9959, respectively). The OLCR unit measured a slightly longer AL in the cataract group and clear lens group (mean difference 0.026 mm and 0.023 mm, respectively), a deeper ACD (0.128 mm and 0.146 mm, respectively), and a flatter K (-0.107 diopter [D] and -0.121 D, respectively). The differences were statistically significant (P<.0001). The mean absolute error in IOL power prediction was 0.455 D +/- 0.32 (SD) with the OLCR unit and 0.461 +/- 0.31 D with the PCI unit (P>.1).
  
  
  CONCLUSIONS
  Measurements were comparable between the OLCR device and the PCI device. A slight decrease (0.050) in the a(0) constant is recommended if the Haigis formula is used.
authors.affiliation: Department of Ophthalmology, University of Southern California, Jules Stein Eye Institute, UCLA, Los Angeles, California, USA. khoffermd@aol.com
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Hoffer
authors.forename: H John
authors.initials: HJ
authors.lastname: Shammas
authors.forename: Giacomo
authors.initials: G
authors.lastname: Savini
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000867:Anterior Chamber / Q000033:anatomy & histology / Q000473:pathology*; D000886:Anthropometry; D001699:Biometry / Q000295:instrumentation*; D002386:Cataract / Q000473:pathology*; D003315:Cornea / Q000033:anatomy & histology / Q000473:pathology*; D005123:Eye / Q000033:anatomy & histology / Q000473:pathology*; D005260:Female; D006801:Humans; D007368:Interferometry / Q000295:instrumentation*; D054023:Lasers, Semiconductor; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D011446:Prospective Studies; D015203:Reproducibility of Results