1. Rehabilitation of visual field loss: Use of yoked prism in a homonymous hemianopic patient
Mary Kutch, OD
Johnathan M. Wainwright VAMC and Pacific Cataract & Laser Institute
Walla Walla, Washington

2. Abstract
Cerebral vascular accidents (CVAs) can have a myriad of neurological, perceptual, and functional effects. A recent CVA victim and retired professor uses yoked prism glasses and trains with the AcuVision1000 to compensate for his homonymous hemianopsia.

3. Patient Background a f x m g
69yowm retired university professor presents for a low vision evaluation 6 weeks following a left occipital hemorrhagic CVA with extension into the parietal and temporal areas
CC: Right side of VF OD considerably constricted, OS “fine,” with improvement since onset
Tilts pages to read, missing ends of long words
No problems recognizing faces, figures, or writing letters & words, but doesn’t recognize groups of letter as words- has to sound them out letter by letter and combine sounds

4. Additional background
Diagnosed by speech & hearing lab with Pure Alexia, aka Alexia without Agraphia
Cognition and memory test normal
Extreme difficulty with figure-ground perception found on later VIP assessment
Goals: Reading with
fluency, resuming driving
and motorcycle riding

5. Exam Findings BCVA 10/10 OD, OS, no Amsler defects OD/OS,
Pupils ERRL,
Slit Lamp- unremarkable for age, IOPs 14mmHg OU,
DFE: c/d 0.3 OU c HRT, Mild ERM OS, Peripheral retina: benign pigmentary changes OU
Goldmann bowl perimetry: Right homonymous hemianopic field loss extending 40’ from fixation OU
No right-side visual neglect, “clock dial” test negative
Baseline Acuvision 1000 testing for functional visual field/hand-eye coordination

6. Treatment Plan Shift perceived visual midline toward seeing side
Testing reveals preferred orientation was yoked base up and right;
Rx yoked prism for separate distance and near glasses to bring the non-seeing visual field into the seeing
Increase awareness of right visual field and eye movement with weekly therapy on AcuVision1000 training board and 20^ yoked base-right prism glasses atop distance Rx
Continue bi-weekly sessions with speech & hearing for re-learning reading fluency with word recgonition, weekly sessions with occupational therapy to increase horizontal eye movements and tracking, and VIP consult ordered.
Referral to driving rehabilitation specialist for evaluation

7. AcuVision 1000 Use / Advanced Features:

8. Training Prism Glasses
In-office use only:
Rotate in frame to
desired angle

9. Progress Report
After only 2 weeks of fixator board therapy and full-time wear of lower amounts yoked prism, PC demonstrated increased speed and accuracy finding right-side targets, which continued to improve in the following weeks
No longer tilting page to read & less difficulty with ends of long words “missing”
Increased saccades/searching eye movement
Word recognition speed increased with other therapy- reduced reading speed of set block of text by 200%
Pt resumed driving with a passenger after go-ahead from driving rehab assessment
Later VIP assessment showed very belabored figure-ground discrimination, which we correlated to finding stop signs and traffic obstacles, and cautioned against driving due to this shortcoming.
Cautioned against motorcycle riding with prism distance Rx as well

10. Other Research Says…
Kunicki found eye-hand coordination improved in both short- and long-term training on the AcuVision 1000 in normal college-age patients.
In clinical trials by Rousseaux, et. al, 79% of stroke patients with spatial neglect signs increased ease in reading single words as well as general function and safety with the use of prism for rehabilitation.
Yoked prism was partially successful for Rossi et al., in a study of 39 stroke patients with homonymous hemianopsia using 15-diopter plastic press-on Fresnel prisms for four weeks. The subjects’ visual perception tests scores improved, but function in the form of activities of daily living (ADL) did not.
While Hedges, et. al. found a lower rate of success than Rousseaux (21% vs 79%) in a similar study, he noted that those who did not find significant functional improvement expressed appreciation that something had been tried, and proper motivation and instruction are essential in the employment of prism therapy

11. References
American Stroke Association
Hedges TR Jr, Stunkard J, Twer A. “Fresnel prisms—their value in the rehabilitation of homonymous hemianopsias” Klin Monatsbl Augenheilkd May; 195(5):
Henderson, Patricia. “Cranial Nerves V- VII and Higher Cortical Function.” Lecture for Indiana University Disease III: Neurooptometry, April 2006.
Kunicki, M. “Can eye-hand coordination be trained on the AcuVision 1000?” Honors Thesis, University of Sydney, Austraila.
Rossi PW, Kheyfets S, Reding MJ. “Fresnel prisms improve visual perception in stroke patients with homonymous hemianopia or unilateral visual neglect.” Neurology Oct; 40(10):
Rousseaux M, Bernati T, Saj A, Kozlowski O. “Ineffectiveness of prism adaptation on spatial neglect signs.” Stroke Feb; 37(2):542-3.
Szlyk JP, Seiple W, Stelmack J, McMahon T. “Use of prisms for navigation and driving in hemianopic patients.” Ophthalmic Physiol Opt Mar; 25(2):

12. Conclusions Thank you for your time!
Don’t forget there are options for rehabilitating your motivated stroke patients with hemianopic field loss to make the most of their remaining vision.
Thank you for your time!