Comparison of 2 laser instruments for measuring axial length

J Cataract Refract Surg. 2010 Apr;36(4):644-8. doi: 10.1016/j.jcrs.2009.11.007.


Purpose: To compare axial length (AL), anterior chamber depth (ACD), and keratometric (K) measurements of 2 laser biometers.

Setting: 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.

Publication types

  • Comparative Study

MeSH terms

  • Aged
  • Aged, 80 and over
  • Anterior Chamber / anatomy & histology
  • Anterior Chamber / pathology*
  • Anthropometry
  • Biometry / instrumentation*
  • Cataract / pathology*
  • Cornea / anatomy & histology
  • Cornea / pathology*
  • Eye / anatomy & histology
  • Eye / pathology*
  • Female
  • Humans
  • Interferometry / instrumentation*
  • Lasers, Semiconductor*
  • Male
  • Middle Aged
  • Organ Size
  • Prospective Studies
  • Reproducibility of Results