slab-off prism

noun1

1. •
   A lens modification used to correct for differences in vision between the two eyes, particularly in cases of anisometropia, in which a prism is ground into the lens of the eye with the stronger prescription, thereby helping to align the visual images seen by both eyes.

   • Although Fresnel prism may be used for full-time wear, if successfully worn, it is possible to replace it by ordering slab-off prism with the slab line oriented vertically. — 2023