Press-on Prism Visual Field Expanders
The Traditional Method
In the past, a straight edged segment of press-on prism was applied
to the side of the field loss on both lenses. Our success with this
method was very limited. Today, however we use a new approach as
The New Method
Following our success with the approach developed by Daniel Gottlieb
in his Visual Field Awareness System, we now use the same approach when
applying a press-on prism. We stamp the press-on prism material with a
round die that cuts a perfect circle. We file the edges to lessen
reflected glare off rough points and mount it on the front surface.
Unlike the traditional method, we mount the prism only on the lens of
the effected side. We want to produce a diplopic image so the patient
quickly picks up objects on the side of the field loss as the patient
makes natural scanning movements.
We find the Gottlieb Visual Field Enhancement System optics to be
far superior to the press-on prism, but as an initial trial lens or as a
less costly alternative, it still has an important place in our
treatment of patients.
InWave Prism System
The application of a prism to enhance visual field has existed for
many decades. The InWave Hemianoptic Lens uses optical quality prisms
to shift the image from the impaired side to the functioning side. The
system has been helpful for patients with hemianoptic field loss. The
prism is molded in either one, or both lenses on or towards the side of
the loss. It shifts the image about twelve degrees nasally allowing it
to be detected within the remaining functional field as the patients
makes mild scanning movements. Along with the prism system therapy is
prescribed to assist adaptation and improve scanning.