Worth 4 Dot testing in normal room illumination tests for which type of suppression?

• A. Shallow suppression
• B. Deep suppression
• C. No suppression
• D. Complete suppression

Answer: (A)

The key idea here is how suppression depth shows up in binocular tests when ambient light is typical for everyday viewing. Worth 4 Dot uses red-green glasses and asks how many dots a patient sees. When both eyes are contributing normally, all dots are seen. If one eye is suppressed, the number of dots reported changes depending on how deep that suppression is.

In normal room lighting, the brain’s suppression tends to be shallow. That means the non-dominant eye is still contributing some input, but its signals are partially blocked. As a result, a patient often reports seeing three dots instead of four. That pattern—three dots under typical illumination—reflects shallow suppression rather than a complete or deep suppression, which would lead to fewer dots and typically requires dimmer conditions or different testing setups to reveal. So the test in a normal-lit room is most sensitive to detecting shallow suppression because it allows partial perception from the suppressed eye while still showing the presence of fusion with the other eye.