In Worth 4 Dot testing, which distance tests central suppression?

In Worth 4 Dot testing, which distance tests central suppression?

• A. 1 ft
• B. 3 ft
• C. 6 ft
• D. 10 ft

Answer: (D)

Central suppression is best revealed when you challenge the binocular system with a viewing condition that minimizes the influence of accommodation and convergence. Worth 4 Dot uses red/green filters so you can see which eye is contributing to the central image by which lights are seen. At a far distance, the eyes don’t need to accommodate as much, and vergence demands are steadier, making any suppression of the eye’s central input more apparent. That’s why testing at a longer distance, such as 10 ft, is used to detect central suppression—the brain’s suppression pattern for the central retina shows up more reliably there. Shorter distances involve more accommodation and convergence, which can mask suppression or alter what lights are reported, so they’re less specific for central suppression.

Central suppression is best revealed when you challenge the binocular system with a viewing condition that minimizes the influence of accommodation and convergence. Worth 4 Dot uses red/green filters so you can see which eye is contributing to the central image by which lights are seen. At a far distance, the eyes don’t need to accommodate as much, and vergence demands are steadier, making any suppression of the eye’s central input more apparent. That’s why testing at a longer distance, such as 10 ft, is used to detect central suppression—the brain’s suppression pattern for the central retina shows up more reliably there. Shorter distances involve more accommodation and convergence, which can mask suppression or alter what lights are reported, so they’re less specific for central suppression.