A preferential looking clinical acuity test: Improvements in implemented microcomputer control

A manually operated preferential looking grating acuity test was modified to include a micro-computer for controlling both stimulus presentation and data acquisition, storage, and analysis. The computerized test requires only one observer-operator and minimizes several testing biases and errors of the manual test. A technique was developed to keep the observer-operator masked during the generation of a transformed staircase. The monocular test time of about 8 min, and the success rate—81% for 224 children aged 2–39 months—compare favorably with our experience with the manual two-operator test. For 39 pairs of age-matched children without visual pathology, grating acuities were 0.6 octaves better with the computerized test. The computerized version was used to measure acuity in 120 children who had, according to clinical examination, poorer vision in one eye than in the other. The suspect eyes showed an average of 0.8 octaves poorer grating acuity. The improvements of computerization were realized without loss of the advantages of the manual test.