The influence of varying the number of characters per row on the accuracy and reproducibility of the ETDRS visual acuity chart
| Autor: | Reuben R. Shamir, Michael Mimouni, Eytan Z. Blumenthal, Yael Friedman, Leo Joskowicz |
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| Rok vydání: | 2015 |
| Předmět: |
0301 basic medicine
Visual acuity Visual Acuity 03 medical and health sciences Cellular and Molecular Neuroscience 0302 clinical medicine Chart Predictive Value of Tests Statistics medicine Humans Computer Simulation False Positive Reactions Vision test ETDRS visual acuity chart Snellen chart Mathematics Reproducibility Vision Tests Reproducibility of Results Test duration Sensory Systems Ophthalmology 030104 developmental biology 030221 ophthalmology & optometry medicine.symptom Line (text file) |
| Zdroj: | Graefe's archive for clinical and experimental ophthalmology = Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie. 254(5) |
| ISSN: | 1435-702X |
| Popis: | As part of an effort to improve upon the Snellen chart, we provide a standardized version of the ETDRS chart utilizing five characters in each row. The choice of five characters contradicts the recommended ten characters per row determined by the NAS-NRC, a committee established to provide guidelines for testing visual acuity. We set out to quantify the influence of varying the number of characters per line on the ETDRS chart with respect to the accuracy and reproducibility of visual acuity measurement. Eleven different ETDRS charts were created, each with a different number of characters appearing in each row. A computer simulation was programmed to run 10,000 virtual patients, each with a unique visual acuity, false-positive and false-negative error value. Accuracy and reproducibility were found to roughly correlate with the number of characters present in each row, such that charts with 1, 3, 5, 7, 9, and 11 characters per row provided accuracy of 0.164, 0.094, 0.078, 0.073, 0.071, and 0.070 logMAR, respectively. A non-linear relationship was observed, with little improvement found beyond seven characters per row. In addition, charts with an even number of characters per row provided higher accuracy than their greater-number odd counterparts. In certain instances, accuracy and reproducibility were not well correlated. Increasing the number of characters per row in the ETDRS chart provides a trade-off between accuracy and test duration. An optimized chart layout would take these findings into account, allowing for the use of different chart layouts for clinical versus research settings. |
| Databáze: | OpenAIRE |
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