Effect of target configuration on the measurement of astigmatism

In this study, five dissimilar crossed cylinder targets were used to determine the cylindrical component of the refractive error of 30 subjects. Our purpose is to see if variations in target configuration affect the results of the test. Although there are statistical differences when targets with different configurations are used in determining astigmatism subjectively, these differences are not clinically significant if we assume that the least amount of error required for clinical significance is +/- 0.25 D. We conclude that dissimilar crossed cylinder targets yield similar astigmatic findings clinically.