Fresnel prisms for field enhancement of patients with constricted or hemianopic visual fields

The concept of visual field enhancement is to increase the effect of the patient's habitual scanning skills by displacing peripheral images toward the residual field and mid-line. This reduces the extent of ocular and head rotation by patients with severely restricted and hemianopic visual fields. High power fresnel press-on prisms are used to effect the image displacement. This paper describes a technique that we believe to be less empirical and more reproducible than previously described in the literature.