Which of the following is NOT a type of cover testing?

• A. Alternate testing
• B. Unilateral testing
• C. Stereopsis testing
• D. Binocular testing

Answer: (C)

Cover testing looks at how the eyes align by briefly occluding one eye and watching how the other eye moves to take up fixation. The usual methods are unilateral testing, where you cover one eye and observe the covering eye’s movement, and the alternating cover test, where you switch which eye is covered to detect any drift that occurs with alternating fixation. Stereopsis testing, however, measures depth perception and binocular function by presenting disparities to each eye while both eyes are open. It assesses how well the eyes work together to perceive depth, not how they align when one eye is covered, so it is not a type of cover testing.