If you pour cold water into a person’s ear, their eyes will move in direction opposite to that of ear . And if you pour water, then their eyes will towards the ear. This is used to test brain damage and is called “caloric stimulation’
Caloric stimulation is a test that uses differences in temperature to diagnose damage to the acoustic nerve. This is the nerve that is involved in hearing and balance. The test also checks for damage to the brain stem.
How the Test is Performed
This test stimulates your acoustic nerve by delivering cold or warm water or air into your ear canal. When cold water or air enters your ear and the inner ear changes temperature, it should cause fast, side-to-side eye movements called nystagmus. The test is done in the following way:
Before the test, your ear, especially the eardrum, will be checked. This is to make sure it is normal.One ear is tested at a time.A small amount of cold water or air is gently delivered into one of your ears. Your eyes should show an involuntary movement called nystagmus. Then they should turn away from that ear and slowly back. If water is used, it is allowed to drain out of the ear canal.Next, a small amount of warm water or air is gently delivered into the same ear. Again, your eyes should show nystagmus. Then they should turn toward that ear and slowly back.Your other ear is tested in the same way.