Introduction to AUs 43, 45, 46
These AUs involve the action of the muscles that you have already learned - those that underlie AU 5 and AU 7. Because their appearance is different from AUs 5 or 7 alone, they are described as separate AUs. AUs 43, 45, and 46 are listed as optional, as we expect that they will not always need to be measured. Although listed as optional, study and score them, except AU 45 (Blink), if they occur in practice scoring.
AU 43 provides a code for comprehensive scoring of the degree of upper eyelid lowering that, at the E level, results in eye closure. It is listed as optional as most studies will not require complete information about this action. However, there are research questions where this information is needed.
In almost all studies, it is best to know when the eyes are closed completely (AU 43E). Therefore, even though scoring AU 43 is described as optional, it is suggested that AU 43E be scored routinely, even when not scoring the other intensities of AU 43.
AUs 45 and 46 are variations on eye closure. In 45, you score a brief eye closure in a blink. You are given a time rule for differentiating blinks (AU 45) from eye closures (AU 43E) and both a time rule and a qualitative feature for discriminating a unilateral blink (AU 45) from a wink (AU 46).