Gottlieb Visual Field Awareness System VFAS
The application of prismatic systems to enhance visual field has existed for many decades. However the results were often poor until the development of the Gottlieb Visual Field Awareness System. It greatly improved our success rates in aiding patients after homonymous hemianoptic visual field loss. Dr. Gottlieb's novel approach was to abandon the traditional equal prism in both lenses for a system placed only in the lens on the side of the visual field loss. The Gottlieb VFAS places a small round prismatic wafer within the patient’s prescription on the side of the visual field loss. The patient’s prescription is fabricated into the wafer.
One key to the success of the Gottlieb VFAS over previous field expansion attempts was that it is placed only in one lens on the side of the visual field loss. Thus it creates a true visual field expansion, not just a shift of the visual field. And his system uses optical quality lenses rather than the poorer optical quality of press-on lenses. This improved the contrast of the expanded image. Patients do not spend time directly looking through the system, but rather perform quick glances that graze the area of the Gottlieb VFAS. This allows the patient to appreciate the visual field expansion without the disruption of continuous double vision.
Patients that use this system demonstrate better mobility, less bumping into objects, and are less startled by people or objects emerging from the side of the visual field loss.
In the past, when field expanding prisms were placed on both lenses, it shifted the visual field but did not truly expand visual field. Dr. Peli of Harvard’s Schepen’s Eye Research Institute demonstrated this through binocular visual field testing through these systems. The monocular visual field expander approach truly increases the function visual field.
The doctor will determine the exact placement of the system based on the results of the patient’s visual field tests. Because the thickness is limited by the size of the Gottlieb Visual Field Expander, the size of the frame is not crucial. Thus tri-focals and other larger multi-focals can be used. Patients with wider faces can be fit with this system as well.
If the patient is blind or has profound loss of vision in the eye on the side of the loss where the VFAS would normally be mounted, it can be mounted in the nasal corner of the better eye. To the right is a demonstration unit used to test the nasal placement of a Gottlieb VFAS. Though with only one eye we do not achieve the same visual field expansion of binocular vision, our patients find this very helpful in shifting images.
Patients using this system report they are now aware of things on the side of their vision loss. They are less likely to run into objects or to be startled by people coming from the side.
In some patients with left hemi spatial in-attention (visual neglect), we find significant improvement in their visual neglect problems while wearing a VFAS.