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Journal of Biomedical Optics

Accuracy of cornea and lens biometry using anterior segment optical coherence tomography
Author(s): Mark C. M. Dunne; Leon N. Davies; James Wolffsohn
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Paper Abstract

We assess the accuracy of the Visante anterior segment optical coherence tomographer (AS-OCT) and present improved formulas for measurement of surface curvature and axial separation. Measurements are made in physical model eyes. Accuracy is compared for measurements of corneal thickness (d1) and anterior chamber depth (d2) using-built-in AS-OCT software versus the improved scheme. The improved scheme enables measurements of lens thickness (d3) and surface curvature, in the form of conic sections specified by vertex radii and conic constants. These parameters are converted to surface coordinates for error analysis. The built-in AS-OCT software typically overestimates [mean±standard deviation(SD)]d1 by +62±4 μm and d2 by +4±88μm. The improved scheme reduces d1(-0.4±4 μm) and d2 (0±49 μm) errors while also reducing d3 errors from +218±90 (uncorrected) to +14±123 μm (corrected). Surface x coordinate errors gradually increase toward the periphery. Considering the central 6-mm zone of each surface, the x coordinate errors for anterior and posterior corneal surfaces reached +3±10 and 0±23 μm, respectively, with the improved scheme. Those of the anterior and posterior lens surfaces reached +2±22 and +11±71 μm, respectively. Our improved scheme reduced AS-OCT errors and could, therefore, enhance pre- and postoperative assessments of keratorefractive or cataract surgery, including measurement of accommodating intraocular lenses.

Paper Details

Date Published: 1 November 2007
PDF: 5 pages
J. Biomed. Opt. 12(6) 064023 doi: 10.1117/1.2821844
Published in: Journal of Biomedical Optics Volume 12, Issue 6
Show Author Affiliations
Mark C. M. Dunne, Aston Univ. (United Kingdom)
Leon N. Davies, Aston Univ. (United Kingdom)
James Wolffsohn, Aston Univ. (United Kingdom)

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