Alternate Cover Testing of the Eyes

If the eyes are perfectly lined then the right eye seeing with the left eye seeing, it's all the same. If you see that kind of vertical movement of the eyes when you're alternately covering them, that's called a skew deviation in this context. Unless the patient has some prior history of eye muscle surgery or congenital crismus problem, that's not common in the general population. It can rarely happen with in er ear disease, but if you areable to see one in this clinical context, is usually a stroke patient.