1. Vision Rehabilitation : Applying strategies for adapting to Visual Field Deficits
Faheemah Saeed, O.D., F.A.A.O.
Associate Professor of Optometry
Low Vision Optometrist
eyedEology
Eyecare Center &
Optical Boutique
5014 West Jefferson Blvd.
Fort Wayne, IN ,
(260)
Eyedeology.net

2. Stroke victims and Vision loss
The number of disabled stroke survivors in the U.S. is estimated to be over 3 million annually.
About 1/3rd of stroke survivors in rehabilitation have either homonymous hemianopia or hemineglect.
These numbers are likely to increase with the aging population and improvements in emergency care for stroke victims.

3. Homonymous Hemianopia or Quadrantanopia
Loss of ½ or ¼ of the visual field that respects the vertical midline and shows on the same side of both eyes.
Common causes include cerebrovascular accident (stroke), traumatic brain injury, tumors or surgery to remove brain tumors.
A stroke to the occipital lobe presents as a congruent defect which may be macular-sparing.

4. Homonymous Hemianopia or Quadrantanopia
May impact mobility and navigation.
Patients frequently complain of bumping into obstacles on the side of the field loss, thereby bruising their arms and legs.
The number of such accidents may decrease with adaptation to the condition, presumably because patients become more cautious and learn to use head and eye scanning techniques to avoid obstacles.
Despite such adaptations, many patients continue to suffer from the effects of limited visual field.

5. Hemispatial Neglect
Hemispatial neglect results most commonly from brain injury to the right cerebral hemisphere, with up to 80% causing visual neglect of the left-hand side of space.
Right-sided spatial neglect is seen more rarely due to the redundant processing of the right space by both the left and right cerebral hemispheres.
In contrast , the left space is only processed by the right cerebral hemisphere in most left-dominant brains

6. Hemispatial Neglect
Though visual neglect has the most striking presentation, neglect in other forms of perception can also be found, either alone or in combination with visual neglect.
Auditory
Somatosensory
Motor
Egocentric (shift of the egocentric reference frame )
Allocentric (attentional deficit between objects and within objects)
Representational / Personal neglect (endogenous attentional deficit)

7. CASE REPORT
A 52 year-old male presented for a low vision exam after being diagnosed with an unspecified visual field defect secondary to a stroke one year ago.
He was mainly concerned about running into things on his left side and perceived reduction in contrast and brightness.
Humphrey visual field test confirmed a left sided homonymous hemianopsia with macular splitting. 

8. Automated Octopus Visual Field test results, showing
Right Homonymous Hemianopsia with macular splitting.

9. Always try to identify Specific Visual goals
“I would like to not bump into things” : Improve mobility.
“I would like things to look brighter”
“Read newspaper efficiently”.

10. Entering Visual Acuity
Distance VA cc (with Snellen chart):
OD: 20/20 -1
OS: 20/25
Near VA sc: (with Light house near card).
0.4/1.0M
0.4/0.8M
His reading speed was “choppy”, often missing the first couple of words in each sentence.

11. Considerations for Near Tasks / Reading
Reading-only glasses + Task- lighting.
Bifocals are not the best option in this case.
Benefits of low-powered LED Magnifiers:
Beyond Magnification.
Improved contrast/brightness.
Assistance via “biofeedback”.

12. Hand-Held Magnifiers http://www.eschenbach-optik.com

13. Fixed – Focus Magnifiers

14. HHM can be used with a presbyopic patient’s distance Rx.
Stand Magnifer is used with a presbyopic patient’s Reading Add.
HH Mag
Fixed Focus Mag
APFlens
Object (printed material)
Closer than the APF
Object (printed material)
@ APF
APFlens
Virtual Image

15. Considerations for Contrast Enhancement
Yellow/ light amber tint.
Tint in Spectacle Rx
Acetate sheets
Typoscopes.
Assist in tracking position on the page.
Eliminate ‘crowding effect’ and background glare.
Pts with VF loss, especially those with a hemianopic defect, have poor saccades and pursuits and benefit from tools that reduce “visual clutter”.
Task lighting.

16. Visual Field Loss Compensation
Field expansion via peripheral monocular (EP design) prism.
Field relocation with binocular (yolked) prisms.
Clip-on mirrors.

17. Field Relocation via Binocular Sector Prism
Field Expansion via Peripheral Monocular sector Prisms

18. Field Relocation via Binocular Sector Prism
Field Expansion via Peripheral Monocular sector Prisms
Restricted to the upper and lower peripheral fields.
Extends across the entire lens, hence effective in any gaze.
Peripheral diplopia is the intended affect.
No effect in 1o gaze
VF is shifted when the patient views through the prism.
Optical scotoma at the center of the lens

19. Better option for patients with visual neglect.
Field Relocation via Binocular Sector Prism
Field Expansion via Peripheral Monocular sector Prisms
Better option for patients with visual neglect.
Better option for patient with HH defect without neglect.

20. Peripheral Monocular Sector EP Prism
The EP lens design offers a novel treatment method for actual field expansion that is measurable by standard perimetric techniques.
The results of the Expansion Prism (EP) study multi-site clinical trial reported a 74% success rate (at 6 months) with this design. 

21. Visual Field Expansion for HH by Optically Induced Peripheral Exotropia
A high power (30 – 40 pd) prism segment is placed base-out on the side of the field loss.
The peripheral location of the prisms causes peripheral exotropia.
As a result, a scene segment as high as the vertical span of the prism is shifted laterally by 15 to 20o relative to the view of the other eye.
Objects that would fall in the scotoma of one eye are seen through the prism in the other eye, providing simultaneous awareness of details within the otherwise absent field of view

22. Scanning techniques for safe travel and increased field awareness.
The pt is instructed to look centrally only through the carrier lens.
When an object of interest is detected through the prism (in peripheral vision), it should then be examined through the prism- free area of the carrier lens, by making a head movement.
The required behavior is similar to that needed with bifocals or progressive addition lenses, where head movements are needed to eliminate the blurry appearance of targets seen through the wrong part of the lens.
Similarly, head movements require deliberate attention at first and should become almost automatic following training and practice (usually 4 weeks).

23. In-Office Instructions/ Training
1. Instruct the patient to look centrally only through the carrier lens, and not through the prisms.
2. With the patient looking straight ahead, move a target in a field expansion area. When the pt is aware of the target, ask him to turn his head to look straight at the target, through the prism-free area.
3. Demonstrate central diplopia, by asking the pt to move his head so that he is looking directly through the prism at the target. Explain that central diplopia should be avoided.

24. In-Office Instructions/ Training
4. Present an open hand so that it can be seen on the non- hemianopic side and through the non-prism part of the lens. 5. Ask the pt touch the hand with his finger rapidly, while still looking towards your eyes. 6. Next, presented only one finger in the same general area. Ask the pt to strike at the finger.

25. In-Office Instructions/ Training
7. Finally, present the finger slightly into the hemianopic side in a field expansion area so that it can be detected through the prism. The apparent position of the finger being shifted towards the seeing side causes confusion at first. 8. This activity should be repeated a few times until the pt is able to touch the finger seen through the prism with a rapid accurate movement. In time, the first reach will become more accurate

26. Automated Octopus VF results, showing
Right Homonymous Hemianopsia - After 4 weeks of vision rehab using EP Monocular Prism.

27. Q: When do I recommend sending a patient for a Low Vision evaluation?
The sooner the better. As soon as they are physically stable and able to get around.
Not immediately though due to the psychology of it-they believe the vision is coming back.
I find it easier to work with them after 2-3 months.
No need to wait 6 months, that is really too long.

28. Q: When do I recommend sending a patient for a Low Vision evaluation?
Patients with longstanding HH (like 10+ years) are really not impressed with EP prism.
Longer standing HH  significantly less effective EP results.

29. Q: How can you help visually, prior to their visit with the Low Vision Optometerist?
Improve contrast  Task lighting, bolder print / font.
Decrease visual clutter  Typoscopes.
Give them a head start by including in their rehab program the following: visual search and scan, word search, picture search, solitaire.
Look for visual neglect.

30. Assessing Visual Neglect by patient’s bedside
Mostly commonly used and quickest is the line bisection test:
In this test, a line a few inches long is drawn on a piece of paper and the patient is then asked to dissect the line at the midpoint. Patients exhibiting, for example, left-sided neglect will exhibit a rightward deviation of the line's true midpoint.

31. Assessing Visual Neglect by patient’s bedside
Another widely used test is the line cancellation test:
Here a patient is presented with a piece of paper that has various lines scattered across it and is asked to mark each of the lines. Patients who exhibit left-sided neglect will completely ignore all lines on the left side of the paper.

32. Assessing Visual Neglect by patient’s bedside
Ask your patient to draw a copy of a picture:
they may neglect the entire contralesional side of the picture.

33. Assessing Visual Neglect by patient’s bedside
Ask your patient to read a page out of a book.
The patient will be unable to orient their eyes to the left margin and will begin reading the page from the center.
Present a single word to your patient
Patient will either read only the ipsilesional part of the word or replacing the part they cannot see with a logical substitute. For example, if they are presented with the word "peanut", they may read “nut” or say “walnut.”[6]

34. References
Peli E. Field expansion for homonymous hemianopia by optically induced peripheral exotropia. Optom Vis Sci Sep;77(9):
Peli E. Vision multiplexing: an engineering approach to vision rehabilitation device development. Optom Vis Sci May;78(5):
Houston KE, Woods RL, Goldstein, Peli E, Luo G, Bowers AR. Asymmetry in the Collision Judgments of People With Homonymous Field Defects and Left Hemispatial Neglect. Invest Ophthalmol Vis Sci June;56 (6):
Papageorgiou E, Hardiess G, Ackermann H, Wiethoelter H, Ditz K, Mallot HA, Schiefer U. Collision avoidance in persons with homonymous visual field defects under virtual reality conditions. Vision Res Jan 1; 52(1):
Giuseppe, Vallar M. Spatial Neglect. Journal of Neurological and Neurosurgery Psychiatry  (9).
Farah, Martha J. (2004). The cognitive neuroscience of vision (Repr. ed.). Malden, Mass.: Blackwell. p. 208. 
Marsel M. Principles of behavioral and cognitive neurology (2. ed.). Oxford [u.a.]: Oxford Univ. Press pp. 174–239.