SUMMARY
Purpose:
To compare the visual acuity measurement using the Snellen E and the Sheridan-Gardner test.
Methods:
Three experiments were perfonned. ln the first, the visual angles and the time necessary to measure the visual acuity of children were compared. ln the second, psychometric functions obtained in different conditions of blur were compared when the Snellen E and the Sheridan-Gardner test were used. ln the third, the ejfect of a low-pass filter on the letters E, H, T, V and O was analyzed.
Results:
The time necessary to measure the visual acuity of children and the visual angles obtained are smaller with the Sheridan-Gardner test than with the Snellen E. The effect of optical blur is greater with the Snellen E than with the Sheridan-Gardner test. Low-pass filtering affects more the E than the optotypes H, T, V and O.
Conclusions:
Even when the visual angles are identical, the considered equivalent tests.
Keywords:
Visual acuity; Optotypes; Filtering; Optical blur