Shortcomings in the current practice of visual acuity measurement

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Encouragement and motivation impact outcomes

In light of these issues, we performed a multicentre study to determine whether encouragement and motivation would have any significant impact on the outcome of the VA measurement using the standard Snellen chart after the initial reading of the test chart.11


When the patient stated what he/she can read, the examiner tried to motivate and encourage the patient to read more, using the following prompts:

1. The patient was asked if he/she could read below the line that he/she stopped at initially.

Each patient's VA was measured three times. Firstly, unaided then with the assistance of spectacles and finally with pinhole. Results both without and with encouragement were recorded and all patients were informed and consented to the study. To investigate the statistical significance of motivation on the patients VA tests, we also applied paired t-test and P values to the results.