Explorative Saccade Training (Homonymous Visual Field Defects – Part 3)


In Part 1 we introduced a book on HVFDs published last year, and in Part 2 highlighted a chapter authored by Dr. Susanne Trauzettel-Klosinski on Adaptation and Rehabilitation in Patients with Homonymous Visual Field Deficits.

The hemianopic orientation disorder

Patients with homonymous hemianopia may or may not be aware of the need to scan.  This awareness or lack thereof is part of a much broader discussion of visual consciousness, and speaks to the various degrees of visual neglect or inattention as operating on a continuum.  It is quite amazing to see the range of adaptability with HH.  Some patients will present to your office already proficient in scanning abilities and strategies, while others appear to be disoriented and/or surprised by objects in their blind field.

HH Graphic Scan

 

Dr. Trauzettel-Klosinski incorporates the figure above into her chapter to illustrate how scanning eye movements utilize the field of gaze to enlarge the “functional visual field”, and how this is further enhanced with head movements are coupled with eye movements.  But the shaded area on the eyes reminded me that we can use modified translucent occlusion patterned after how we use binasal occlusion for esotropia.  The idea is to place occlusion tape or filters partially into the seeing field – in the case of right homonymous hemi one would place the tape between the limbus and outer canthus on the left lens, and between the limbus and inner canthus of the right lens.  This would “force” the patient use exploratory saccades and/or head movement in order to maintain visual awareness.

There are many ways to train explorative saccades, and they are most useful for HH but have other applications as well.  Our favorite procedure for explorative saccades is the Sanet Vision Integrator (SVI) and in particular quadrant loading – which is an interactive and expansive approach that may even be combined with the type of sector occlusion as described above.  The SVI is at its best for putting the elements back into place for reading readiness.

Press LitesAs a “low tech” approach, and for exploratory saccades in free space as opposed to on- screen on in a 2-D plane, we gravitate toward Press Lites activities.  In an article in Optometry & Visual Performance, I described how to utilize these procedures for exploratory saccades in the context of visual field awareness and the functional visual field.  There is considerably more that could be written about the subject, but suffice it to say that work in this area demands considerable time and patience, on the part of the doctor, therapist, patient, and support system.

slow_turtle_21710

 

3 thoughts on “Explorative Saccade Training (Homonymous Visual Field Defects – Part 3)

  1. Good examples for therapy. The literature also uses tinted lenses in a sectorial fashion like you describe similar to a binasal. I have tried them but seems not very therapeutic, but certainly an option to train saccades. Another key component is that often patients have mixed HH and USI. I would suggest that any head movement training stimulates vestibular input which increases attenition to the neglected side. A-shift head to right, stop, eyes maintain central fixation and you have a post vestibular stimulation to the right side. But when you return, you get a post vestibular stimulation to the left side, so you have to work harder to maintain attention to the left side. So we use that, as well as ‘blindsight’ activities, working on spatial memory in the non-seen field.

    • Precisely, Curt. The sector tapes would only be intended for therapy, to provide a type of feedback. The theory would be that there is some awareness that the habitual field has been diminished – a large enough amount that it registers, but not so large as to cause the patient to shut down. What we’ve also done in select cases is use a bilateral integration approach, with the sequence in rehabilitation mirroring habilitation: Angels-in-the-Snow progressing to Slap Tap progressing to to Infinity Walk, with Infinity Walk triggering vestibular. Hemineglect might also be present in the somatosensory system, in which case vestibular might hinder visual rather than bootstrap it. But, to borrow a phrase, once you’ve met one hemianiopic patient, you’ve met one hemianopic patient … so we use all the tools at our disposal!

  2. The illustrations of the darkened blind field and how is reduces with eye movements was helpful and instructive. We all suffer from a field loss, however: the half of the world behind our heads. Parent’s of young children have to develop eyes in the backs of their heads, or at least use visualization and head turning to eliminated their “field loss.” Drivers use head turns and mirrors to overcome their ignorance of the world behind them. The ‘field losee’ behind, however, is not dark, just sometimes forgotten.

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