Clinical Evaluation of the MKH-HAASE Stereoacuity Tests

Background: H.J. Haase developed a set of tests for measuring associated phoria and stereopsis using a variety of different targets for each. This study investigates the test-retest repeatability of the distance and near stereopsis tests for the MKH-Haase charts. Methods: MKH-Haase contour (Line Test) and randomdot (Steps Test) stereopsis tests were measured at distance and near for 34 symptomatic and 40 asymptomatic participants on two different sessions. The MKH-Haase protocol requires the stereoacuity to be measured twice within a session; once for crossed and once for uncrossed disparities. Results: Direct comparison within sessions did not reveal any significant differences in MKHHaase stereoacuity tests between symptomatic and asymptomatic groups; hence, the two groups were pooled for further analysis. The within and between-sessions repeatability of most MKH-Haase stereoacuity tests results was good at both distance and near. However, there were a few exceptions to this general finding. Crossed disparity thresholds were significantly lower than uncrossed disparities within the first session at distance for both Line and Steps tests. The differences between sessions for both disparities were not significant for all stereoacuity tests except the Steps test at distance. Conclusions: MKH-Haase stereoacuity charts are considered reliable tests for measuring local and global stereothreshold at both distance and near.