Yoked prisms and cerebral visualimpairment: Enhancing the experienceof ambient vision

Background: Perceptual visual impairment leads to impaired
functional vision in children with cerebral visual impairment.
Yoked prisms have been used in behavioral vision therapy for
children with autism (dysfunctional dorsal visual processing
pathway) and in neurorehabilitation to treat visual neglect,
hemianopia, and abnormal egocentric localization. In particular,
they are employed for treating perceptual visual problems.
Purpose: To share our experience in implementing yoked
prisms and their impact on the rehabilitation of children with
cerebral visual impairment‑related perceptual vision disorders.
Synopsis: The first child with periventricular leukomalacia
exhibits no eagerness to explore her new environment along
with poor grasp. With 4‑PD base‑down prisms, she explores
her surroundings and appreciates her lateral supports. Her
grasp improved as well. The second child with cerebral visual
impairment exhibits difficulty in climbing downstairs with poor
obstacle negotiation. This could be due to impaired inferior field
awareness or optic ataxia. With 4‑PD base‑down prisms, the field
shift toward the apex helps him to climb downstairs without
difficulty with an improved obstacle negotiation. The third child
prefers a closer look at the object of interest along with poor
hand-eye coordination. We employed 4‑PD base‑down prisms in
her rehabilitation session. She showed good improvement in her
hand-eye coordination.
Highlights: Poor hand-eye coordination,
difficulty climbing downstairs, optic ataxia, impaired field
awareness, and triggering spontaneous exploration in children
with perceptual visual problems can be effectively tackled by the
simple incorporation of yoked prisms.