Vergence facility is tested with which method?

Vergence facility is tested with which method?

• A. By measuring the speed of accommodative response
• B. By presenting moving targets at different depths
• C. By assessing accommodation speed at near
• D. By prism flippers (±2.00 D) and a near target to determine cycles per minute

Answer: (D)

Vergence facility measures how quickly and smoothly the eyes can change vergence as depth demands shift. The best way to test this is by using prism flippers that alternate ±2.00 diopters while the patient views a near target (about 40 cm). Each flip forces the eyes to converge and then diverge (or vice versa) to maintain single vision. By counting how many complete vergence adjustments can be made in one minute, you get the cycles per minute score. This method directly challenges the vergence system with controlled, repeatable disparity changes while keeping accommodation relatively stable, thanks to the near target, so the result reflects vergence dynamics rather than lens focusing. Other methods either assess accommodation speed or use moving targets to imply depth, which doesn’t isolate vergence facility as cleanly.

Vergence facility measures how quickly and smoothly the eyes can change vergence as depth demands shift. The best way to test this is by using prism flippers that alternate ±2.00 diopters while the patient views a near target (about 40 cm). Each flip forces the eyes to converge and then diverge (or vice versa) to maintain single vision. By counting how many complete vergence adjustments can be made in one minute, you get the cycles per minute score. This method directly challenges the vergence system with controlled, repeatable disparity changes while keeping accommodation relatively stable, thanks to the near target, so the result reflects vergence dynamics rather than lens focusing.

Other methods either assess accommodation speed or use moving targets to imply depth, which doesn’t isolate vergence facility as cleanly.