Alternatively, the use of slab-off
or biprism single vision lenses could be considered should the patient want one pair of spectacles.
prism is an alternative approach to reduce the effects of vertical differential prismatic effect in anisometropic patients.
Prism-free optics or peri-ballast is used to incorporate the stabilising prism only in the peripheral areas of the lens, for example UltraVision LiteWave (Figure 2) and the slab-off
prisms give equal thickness at both the base and 3 and 9 o'clock positions.
The "revolutionary" back toric design features double vertical asymmetric slab-off
and horizontal right and left ballast for axis stabilisation.
), posterior toric, chamfering, truncation, and combinations (i.e.