Dynamic Visual Acuity (DVA)
Dynamic Visual Acuity (DVA) is a test to evaluate the vestibulo-ocular reflex (VOR). The function of the VOR is to fixate images of objects in the eyes that we see in the surroundings when we move our heads or when the head moves or when both the head as well as the visual object moves. If the VOR is defective the images are not steadily fixed in the eyes and the subject feels vertiginous. Poor VOR is one of the common reasons for which a patient presents to the doctor with head spinning or imbalance and the VOR needs to be tested in all patients who present to the doctor with vertigo or imbalance. DVA is one of the tests to evaluate the functional status of the VOR. The test is very much like an eye test that the optometrist does to test a patient’s vision. There are different letters of the alphabet in different sizes projected in a computer screen and the patient is asked to read the letters with the head fixed and while moving the head at a particular speed. The test takes about 10-15 minutes time in cooperative patients and is a non-invasive painless test that does not cause any vertiginous sensation to patients.