Visual field loss following a CVA or TBI often affects bilateral fields (homonymous hemianopia). The field loss is thought to occur due to injury in an area of the occipital cortex or visual portion of the brain related to either the left or right visual field. The medical approach is to inform the patient that they should wait one year to determine if the visual field opens on its own and if not the patient is then told that it is unlikely that the vision in the corresponding field will return. While it is assumed that the visual field loss occurs from a lesion in a portion of the occipital cortex, the majority of MRIs and CT scans are often found to be negative.
PAVE™ utilizes a new concept related to bi-modal visual processing to assess and provide a method of rehabilitation. It has been found clinically that the visual field is a function of both portions of the bi-modal visual process-: the parvo or focal process and the magno or ambient (spatial) process. Standard testing for visual fields through ophthalmologists and optometrists evaluates only one component of the visual process by presenting detail information to stimulate the focal or detail portion of the bi-modal process. 7, 8
It has been demonstrated clinically that when treatment is directed toward the spatial or ambient visual process, a field expansion can occur in a relatively short period of time. The assessment and rehabilitation can be delivered through a computer-based instrument with expanded monitors to provide rehabilitation for the peripheral field dysfunction. The concept has been tested successfully with our prototype. Early stage pilot tests have demonstrated expansion of the visual field by as much as 30-40 degrees within relatively short periods of time. The therapy can be delivered by a technician and potentially can be used in offices and hospitals as well as for home-based programs.
The magno and parvo receptors are different in several ways. The parvo cells respond more slowly and are stimulated by detail. The magno cells offer a fast relay, and provide information that is responding to motion and spatial orientation. It is no surprise that they affect our lives differently. Clinically, the concept that the spatial visual process is primary for ambulation is new. Testing for visual field loss has only been determined through evaluation of the parvo cells. This is contrary to the understanding that the ambient or spatial visual process is directly related to movement, balance and the stabilization of the peripheral visual fields.
The unique characteristic of the PAVE™ is that it utilizes the most current approach of working with both visual processes. Following a neurological event such as a CVA or TBI there is a compromise of the spatial visual process. Typically, when that occurs, the person is unable to maintain both systems and reverts to concentrating with the focal system that then compromises the peripheral visual field.
The PAVE™ works by disassociating the bi-modal visual process enabling the re-establishment of the spatial visual field through the ambient process that is delivered through the magnocellular system. In addition, the patient’s motor system is used to enhance the signals to the ambient system and its spatial awareness to engage the ambient spatial visual field.
With repeated therapy, the patient rehabilitates the preconscious nature of the ambient system as the platform of the spatial visual field. The re-balancing of the bi-modal visual process provides the means for rehabilitation of the visual field. There are no other known instruments that will provide the rehabilitation of visual field in this manner.
PAVE™ is patented and invented by William Padula, OD and William Padula, PhD. US Patent No. 8567950.