Heterophoria as a measure of subjects' alertness during recovery from general anesthesia.

The purpose of the study was to measure the influence of subjects' alertness on heterophoria. An experimental group of 43 patients was measured with the Maddox Wing test for heterophoria. Exophoria was greater 1 1/2, 2 1/2, and 3 1/2 hr. after the end of general anesthesia than at baseline level. Data for a control group of 25 did not vary on the Maddox Wing over four hours. The baseline level was not different between the two groups, so heterophoria as measured with the Maddox Wing can be used to evaluate subjects' alertness during recovery from general anesthesia.