[How should visual acuity be measured?].

1. The ordinary Snellen chart with letter optotypes is not suited for research purposes. Unequal legibility of letters, unequal number of optotypes on rows of the chart and unequal progression of letter sizes limit the usage of such charts for screening purposes only. 2) The results of our computerised method for determining of visual acuity correlate very well with the results gained using the standardised Landolt optotype chart (r = 0.931). Our method brings whole line acuity, threshold visual acuity with its variability and a new parameter of line slope (decrease of correct readings from 95% to 5%), expressed in standardised rows (log MAR = 0.1). The results are printed on a simple printer and stored in a database.