Visual field cuts are common among stroke survivors. This common consequence can cause safety issues, falls and loss of driving privilege. Assessing and understanding visual field cuts are discussed here. This post will discuss the techniques I use to improve visual field cuts following stroke and TBI.
Having the patient’s vision assessed by an eye doctor is always the first step. Understanding your patient’s vision history will be vital to understanding current visual complaints. Ideally, an Easterman assessment will be completed with the therapist getting a copy of the exam to be aware of the baseline. Periodic re-assessment of the visual field will be required to check for progress. I typically recommend reassessment after 10 visits. If no progress has been made at this point, I recommend the patient stop the treatment. In past cases, if no progress was made after 10 treatments and the treatment was continued, no progress was made after an additional 15 treatments.
Some patients with field cuts do better than others. In my experience, those with neglect, particularly those with poor awareness of their condition, tend to become frustrated with the interventions as they feel they are wasting time attempting to correct a condition they do not think they have.
I have had the most success with patients having fields cuts related to occipital lobe strokes as opposed to strokes caused by middle cerebral artery issues. These MCA strokes have a higher incidence of attention/neglect (particularly left side affected). While I have had more success with younger patients, age should not disqualify a patient. Medical instability and neurological history all play a role in reaching the patient’s goals with results not being as good for patients with more complex medical histories.
What is success?
The typical patient with field cut loss is wanting to resume driving. Many states have specific visual field requirements for driving (130 degrees in Florida). Investigation of this requirement will be a part of helping the patient with the visual field cut. As therapists know, driving is a complex task with adequate vision being only part of the skills needed to safety operate a vehicle.
While the patient may not show sufficient improvement to met the states requirement for driving, the patients do tend to show improved spatial awareness and safety during ambulation and basic ADLs. I explain all of these things to the patient during our initial assessment and explain that I do not guarantee the will be able to resume driving following our treatment.
The Treatment Session
In early sessions, I begin with monocular scanning with cuing to keep the head still during these tasks, usually focusing on central field scanning (a setting on the SVI that encompasses the middle 2/3rds of the screen rather than the full screen). The early goal is to facilitate searches in the missing field without head movement. I will also do quadrant loading in the affected field, continuing to monitor for head movement.
My goal with field scanning is to see quadrant times, get closer together with the goal being less than .4 of a second difference between the fastest and slowest quadrants.
The patient performs saccade strips with the red/blue letters (called monocular fixation in a binocular field-“MFBF”) starting with the strips close together and widening until the saccades become inaccurate (noted by difficulty finding the next line on the right to left sweep or head movement). We practice at this width until there is sufficient improvement to continue.
The hand speed task as well as the saccades 1 and 2 tasks on the Sanet are also useful in improving field scanning.
Having the patient do word searches on paper has been a useful addition to the field cut interventions as a home program. This may initially be frustrating but, with practice, the patient will improve.
I typically apply binasal occlusion to help improve peripheral awareness during the first session for the patient to wear at all times.
When available, Peli-Lens are added to the patients glasses to be used when outside of treatment sessions as well.
Other Vision issues
It is not unusual for the stroke survivor to report other visual issues. I commonly find that while patients have good fusion, the transition from near to far may be slow. This can be improved with convergence/divergence tasks.
Does it work?
I have successfully helped over half of my field cuts patients meet the state’s visual requirements for driving. Given the complex nature of driving, some have chosen not to resume driving for other reasons such as reduced reaction time or cognitive issues resulting from their stroke. Only the eye doctor can assess the patients visual filed and approve them to resume driving.
Without a device like the Sanet or Dynavision, field cut remediation would be much more difficult. Use of letter/number searches on a chalkboard may be helpful and worth trying. The saccades tasks on EyeCanLearn.com may also be helpful.