Chonnam Med J.  2015 Aug;51(2):91-96. 10.4068/cmj.2015.51.2.91.

Factors Affecting the Accuracy of Intraocular Lens Power Calculation with Lenstar

Affiliations
  • 1Department of Ophthalmology, Chonnam National University Medical School and Hospital, Gwangju, Korea. kcyoon@jnu.ac.kr

Abstract

This retrospective study was performed to compare refractive outcomes measured by conventional methods and by use of the Lenstar biometer and to investigate the factors affecting intraocular lens (IOL) power calculation with Lenstar with and without IOL-constant optimization. The study included 100 eyes of 86 patients who underwent cataract surgery. Corneal curvature was measured with a manual keratometer (MK), automated keratometer (AK), and the Lenstar biometer, and axial length (AL) was measured by A-scan and Lenstar. Mean numerical error (MNE) and mean absolute error (MAE) were compared between AK and MK with A-scan, and Lenstar with and without optimization. Factors affecting the accuracy of the IOL power calculation by use of Lenstar with and without optimization were analyzed. No significant differences were observed in the MNE or MAE among the devices. The proportion of MAE within 0.5 D was higher for Lenstar with optimization (62.7%) than without optimization (46.2%). The proportion of MAE within 0.5 D was 62% and 58% for MK and AK with A-scan, respectively. Without optimization, the MAE was smaller in eyes with ALs between 23 mm and 25 mm (p=0.03), whereas it was smaller at higher corneal powers when the IOL constant was optimized (>44 D, p=0.03). The IOL power calculations showed no significant differences among the devices, but the results of MAE within 0.5 D by use of Lenstar without optimization were worse than those of conventional methods. The AL influenced the accuracy of refractive outcomes determined by using Lenstar without optimization, and corneal curvature was shown to affect the accuracy of refractive measurements using Lenstar with optimization.

Keyword

Axial length; Corneal topography; Lenses, Intraocular

MeSH Terms

Cataract
Cimetidine
Corneal Topography
Humans
Lenses, Intraocular*
Retrospective Studies
Cimetidine

Figure

  • FIG. 1 Bland-Altman plots of keratometry using (A) Lenstar and an automated keratometer, (B) Lenstar and a manual keratometer, and (C) automated keratometer and manual keratometer (95% limits of agreement for keratometry difference: Lenstar - automated keratometer, -0.84 to 0.71; Lenstar - manual keratometer, -1.14 to 0.90; automated keratometer - manual keratometer, -1.18 to 1.07).

  • FIG. 2 Bland-Altman plot of the axial length between Lenstar and A-scan (95% limits of agreement for axial length difference: Lenstar - A-scan, -0.53 to 0.19).


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