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.
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.
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.
As 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.