In my last blog,  I shared my dismay at the effect the aging process was having on the vision of my friends and (sigh!) myself.   This led me to consider the importance of vision in using AAC and the visual issues which might occur in those who have experienced a neurological event such as a stroke or brain injury.  

Previously, we discussed basic visual characteristics of AAC that might be considered during the evaluation process for both light-tech and high-tech AAC when an individual demonstrates visual perception problems.  I shared how these visual characteristics are reflected in DynaVox products and potential modifications to these characteristics which might be applied based on the needs of the individual.   

Below, I will discuss a few of the specific visual issues we might see in individuals following neurological event and some practical methods of addressing them. 

Note:  Consult your physician regarding diagnosis of visual issues following a neurological event.  Consult your medical/clinical supports (physician, speech-language pathologist and/or occupational therapist) and to assist you in selecting compensatory strategies. 

 Visual Field Cut – Inability to see portions of the typical range of vision (e.g., various degrees of loss of peripheral vision, loss of half the visual field).  An augmented communicator may not see a portion of the book, board or device. 

• Position the device within the useful visual field. 
• If the entire device cannot be placed within the visual field, consider using the portion of the screen within the visual field for content. 
• If appropriate, teach the individual to compensate for the visual field cut by moving his head to scan the entire screen (see additional ideas in “Visual Neglect” below). 

Visual Neglect – Decreased attention to or awareness of one portion of the visual range.  If a left visual neglect is identified, the individual may not be aware of what is entering, present in or leaving his visual field on that side.  When using AAC, he may not attend to vocabulary on the left side of the screen.   

• Place a colorful strip of paper or tape down the side of the device (on the device casing, not on the screen!).  Cue the individual to look all the way over until he sees the line.
   
• If additional assistance is required to remind the individuals to which direction to look, you could add an arrow pointing the appropriate direction as well.   
• Strategies related to Visual Field Cuts may also be beneficial based on the individual’s level of awareness of his deficit. 

Rancho Los Amigos National Rehabilitation Center has a useful handout describing Visual Neglect and Visual Field Cuts available at http://www.rancho.org/ot0033.pdf. 

Involuntary Eye Movement (Nystagmus) – Repeated, uncontrolled movement horizontally or vertically which may affect vision.  

• Politano & Scharre (reference below) suggest that “many patients experience an area within their visual field where the nystagmoid movement is decreased” (called a null point) and to “consider null point when determining optimal position for the display.”

 Double Vision 

• Some patients with double vision have indicated to me that larger type and/or images that are not as visually complex are easier for them to discriminate and use.  Ask the individual to share her preferences with you by showing two or more options and asking which is better.  I would encourage you to provide a way for the person to indicate that they are the same as well.   

Decreased Visual Acuity – Reductions in the clearness of vision. 

• Consider larger targets and less complex visual displays (see previous blog).  
• Use the Zoom feature in the V/Vmax and Xpress which increases the size of an area around a point you select based on the criteria you set (e.g., percent increase, etc.).   Read more about this feature in the Knowledge Base by typing in “zoom” and selecting the device that you have.
  
  

 The suggestions above have focused on providing compensatory strategies to make use of visual skills.  It should be noted that visual representation of language which is used most frequently in AAC can be supplemented with auditory feedback as well.  

As we age, many of us experience changes in our vision (as well as many other things!).  Each time we pull out our reading glasses, ask someone else to read something to us or realize that our arms just aren’t long enough, we realize the importance of our vision and the effect that vision has in functioning during daily activities.  

Neurological events can result in visual issues.  It is important that these are effectively diagnosed and treated regardless of the individual’s communication status.  However, it is essential for those who use AAC which typically represents language visually.  

Reference:

Politano, P. & Scharre, J. (n.d.).  Functional Vision Skills for AAC Systems.  Retrieved from http://tigger.uic.edu/~politano/VISION_FOR_AAC.htm  on April 30, 2010.