What type of prism effect does a standard slab-off create?

A standard slab-off procedure is designed to aid individuals with vertical imbalance, particularly when one eye has a significantly stronger prescription than the other, which can cause discomfort and visual distortion. The slab-off technique involves creating a wedge-shaped prism in the lens of the eye with the lesser prescription.

In the case of a slab-off, it introduces a base-up prism effect at the near vision. This effect is helpful because it offsets the tendency for the eye with the higher prescription to be more dominant, creating a more comfortable binocular vision experience when focusing on nearby objects. Essentially, the base-up prism helps align the visual axes of both eyes, allowing for better coordination and balance during near tasks.

This application of the slab-off technique is essential in providing relief for patients with vertical heterophoria, enhancing their quality of vision for near tasks. Therefore, the introduction of a base-up prism serves a critical role in the adaptation process, allowing for smoother visual transitions when shifting focus between distances.