Neurorehabilitative Optometry

Within the United States, there are approximately forty million people living with a neurological dysfunction such as a cerebrovascular accident (stroke), traumatic brain injury (TBI), cerebral palsy (CP), multiple sclerosis (MS), autism, etc. 

There is an emerging area within optometry called Neuro-Optometric Rehabilitation.  The optometrist practicing this specialty works as part of an interdisciplinary team of professionals to assist in vision rehabilitation.

Often, individuals who have had a neurological event will experience vision problems.  These problems are often the result of dysfunction between areas of the brain that match information with vision and balance/movement centers known as the sensory-motor system.  These dysfunctions can cause problems with coordination and integration of the eyes known as binocular dysfunction. 

People may also experience double vision (diplopia) and eye tracking problems causing difficulty with reading.  Often, balance and posture difficulties can occur due to a mismatch of information between the visual system and other balance centers.  Following a stroke (CVA) or TBI, people may experience a variety of symptoms such as: 
   1 - difficulties with balance,
   2 - double vision,
   3 - seeing words appear to move when reading,
   4 - eye strain and fatigue,
   5 - glare sensitivity (photophobia), and
   6 - an inability to be exposed to busy crowded environments such as shopping malls and grocery stores.  The latter  can even lead to panic attacks.

There are other symptoms that may be caused by visual processing disorders that are often not associated with the visual system during a routine eye examination.  If the eye doctor is not familiar with visual processing problems caused by a neurological event, the examiner may only find that the eyes are healthy and tell the patient that there is nothing wrong with their eyes.

The answer to understanding that the symptoms may be caused by visual processing problems in the brain and not in the eyes lies in recognizing that there are multiple areas in the brain that are responsible for matching information from the eyes with other sensory-motor systems such as the kinesthetic, proprioceptive, and vestibular systems.  Of these, there are two primary visual processing functions known as the focal process and the ambient (spatial) process.

The focal visual process is a detail-oriented process relating to our attention and concentration.  The ambient process, however, is related to the sensory-motor systems that affect our ability to organize balance and movement.  The ambient process provides visual information about “where” we are in space.  When matched with other sensory-motor information, it becomes the “grounding” or stabilization of the higher level focal process.  The ambient process also supports binocularity by assisting with integration of the images received from the two eyes as well as organizing the stabilization of what we see when we shift our eyes across a line of print when reading.  This stabilization of vision from the ambient visual process is also responsible for helping us walk through a crowd of moving people without becoming disoriented.

Following a neurological event, destabilization of the ambient visual process can cause Post Trauma Vision Syndrome (PTVS) and Visual Midline Shift Syndrome (VMSS).  These conditions can be treated through the prescription of specially designed prism glasses which can stabilize the ambient process and thereby reduce or eliminate symptoms.  Yoked prisms can be used to realign concepts of visual midline that often shift in those who are neurologically challenged.  After a CVA or TBI, the visual midline can shift causing a person to lean in posture or drift when walking.  VMSS can often occur when there is a homonymous hemianopsia (visual field loss on one side).  Yoked prisms can be very effective in increasing weight bearing on the affected side in conditions of hemiparesis (weakness on one side) or reducing “toe-walking” for those with autism and cerebral palsy. 

Through Neuro-Optometric Rehabilitation, the optometrist can offer treatment regimens that include lenses and prisms to affect the complicated imbalance between vision and the sensory-motor system. For additional information and/or a referral to a doctor of optometry practicing Neuro-Optometric Rehabilitation, please contact the Connecticut Association of Optometrists.