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

Comparison of 2 laser instruments for measuring axial length.

Author information

1
Department of Ophthalmology, University of Southern California, Jules Stein Eye Institute, UCLA, Los Angeles, California, USA. khoffermd@aol.com

Erratum in

  • J Cataract Refract Surg. 2010 Jun;36(6):1066.

Abstract

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.

PMID:
20362858
DOI:
10.1016/j.jcrs.2009.11.007
[Indexed for MEDLINE]

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