Neurologically, could saccadic eye movement training (scanning therapy) have good results in people who suffer from hemianopsia from brain injury?
There are a variety of rehabilitation strategies for people with hemianopsia — a visual field loss where half of one’s visual field, either vertically or horizontally, is gone; the person cannot see it. Most of these strategies are designed to train compensatory methods for the missing hemi field. These include prisms and various scanning techniques. Another strategy — vision restoration therapy — is different in that the premise is that through repetitive stimulation of the boundary of the hemi field, the brain will change so that vision is restored in a portion of the missing field. This strategy is controversial and the published results suggest that the amount of restored visual field is fairly small, perhaps on the order of 5 to 10 degrees. Other studies do not find this level of improvement.
None of the rehabilitation strategies have been shown to be effective in controlled clinical trials. This doesn’t mean they don’t produce benefit. It merely means that we don’t have enough information to definitively say that any method reliable leads to improvement.
Articles that have extensively reviewed the scientific literature find that scanning therapy is a promising rehabilitation strategy. We often use it in my clinic and most patients seem to benefit in that they are better able to safely travel, reading may improve, and everyday tasks seem easier.
In short, scanning therapy isn’t a cure nor is there a guarantee that everyone will have good results. However, there is enough evidence that with treatment from a qualified therapist somepeople with hemianopsia may benefit. The starting point should be seeing an ophthalmologist or optometrist who specializes in neurological vision loss. These professionals can perform a comprehensive eye examination, determine if prisms or other therapy is your best option, and recommend a qualified therapist to teach the use of prisms or to provide scanning training. Whatever rehabilitation strategy you select, you should consider yourself a partner in your own care. That simply means you are a member of the therapy team and will have to do some of the work in cooperation with the other team members, including your eye care provider and therapist. It may also be helpful to include a family member or close friend on this team as he or she can reinforce training lessons and provide feedback on progress. Experience suggests that if people put in their share of effort the outcome is likely to be positive. But as with all treatments, if you are not seeing a positive effect in several months you should reconsider if this is right for you.