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Graefe's Archive for Clinical and Experimental Ophthalmology
Published in: Graefe's Archive for Clinical and Experimental Ophthalmology 7/2019

01-07-2019 | Low Vision

Is conversion of decimal visual acuity measurements to logMAR values reliable?

Authors: Asimina Mataftsi, Dimitrios Koutsimpogeorgos, Periklis Brazitikos, Nikolaos Ziakas, Anna-Bettina Haidich

Published in: Graefe's Archive for Clinical and Experimental Ophthalmology | Issue 7/2019

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Abstract

Purpose

To assess if conversion of decimal visual acuity (VA) to logMAR is reliable for clinical and research purposes.

Methods

Right eye VA of 74 consecutive patients was measured with 5 min interval, using (a) the ETDRS chart (VAlog), (b) a decimal chart at 6 m (VA6m), and (c) a decimal chart at 4 m (VA4m). VA was the smallest line whereby four of five optotypes were correctly identified. Decimal scores were converted to logMAR using the formula logMAR = −log(decimal acuity). The agreement between VAlog, VA4m, and VA6m was assessed by the Bland-Altman method.

Results

Linear regression analysis of the difference between VAlog and VA6m or VA4m showed a significant slope (p = 0.001), with greater disagreement at higher VA values, i.e., poorer acuity. There was considerable lack of agreement, with discrepancies of up to 0.2 logMAR when VA was measured around 0.5 logMAR.

Conclusion

Converting decimal VA to logMAR produces overestimation of its true value, especially in lower acuities.
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Metadata
Title
Is conversion of decimal visual acuity measurements to logMAR values reliable?
Authors
Asimina Mataftsi
Dimitrios Koutsimpogeorgos
Periklis Brazitikos
Nikolaos Ziakas
Anna-Bettina Haidich
Publication date
01-07-2019
Publisher
Springer Berlin Heidelberg
Published in
Graefe's Archive for Clinical and Experimental Ophthalmology / Issue 7/2019
Print ISSN: 0721-832X
Electronic ISSN: 1435-702X
DOI
https://doi.org/10.1007/s00417-019-04344-9

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