In Hess-Lancaster testing, which flashlight color is typically given to the patient to match the examiner's light?

• A. Red flashlight
• B. Green flashlight
• C. Blue flashlight
• D. Yellow flashlight

Answer: (B)

In Hess-Lancaster testing, the patient’s task is to align their own light with the examiner’s light on a translucent screen, so you can map how the eyes move together or separately. The patient is given a green flashlight to match the examiner’s light because using the same color makes it straightforward to see when the two lights coincide on the grid. This simultaneous, color-matched alignment reveals the pattern of ocular motility and highlights any muscles that are underacting or overacting, helping identify palsies or restriction. The green color is chosen for clear visibility and to keep the two lights distinguishable on the screen while the patient performs the matching.