Figure 1.

Schematic illustration (right eye with base-in prisms) of full-field prism configurations. (A) Meniscus full-field prisms mounted with the bevel positioned at the front surface for the best cosmetics. (B) Flat full-field prisms with the bevel positioned at the back surface for mounting to the frame (outward prism serration). (C) Flat prisms mounted with bevel positioned at the front surface (eyeward prism serration). Due to the difference in back surface shape (curved, flat or slanted), the angle of incidence, i (from the normal to the back surface, see the inset), varies with prism configuration and direction. The smaller angles of incidence at the base end (blue dashed lines) in (A) and (C) result in lower effective prism powers than in (B).