Interventions for vision impairments post brain injury: Use of prisms and exercises. Dr Kevin Houston Talia Mouldovan

Transcription

1 Interventions for vision impairments post brain injury: Use of prisms and exercises Dr Kevin Houston Talia Mouldovan

2 Disclosures Dr. Houston: EYEnexo LLC, EyeTurn app Apps discussed are prototypes and are not being promoted for sale.

3 Vision Rehabilitation Use of lenses, visual assistive devices, therapies, environmental modifications and strategies to enhance vision and minimize functional impairments caused by vision loss

4 Spaulding Rehabilitation Hospital Boston

5 Terminology Esotropia (deviated in) Exotropia (out) Hypertropia (up) Hypotropia (down)

6 Rates of Strabismus at Spaulding 110 cases August 2015 to March 2016 Most common: CN III, IV, VI, convergence insufficiency

7 Diagnosing Strabismus Cover Test with Prism Neutralization Hirschberg/ Krimsky test

8 Diagnosis: Motor Field Test Measure strabismus in different positions of gaze

9 Ocular Convergence Activation of both medial recti to rotate the eyes inward, typically for near viewing

10 Diplopia, Visual Confusion, Rivalry, & Suppression Diplopia (Double Vision): Seeing the same object twice Visual Confusion (Overlapping images): Seeing different visual stimuli in the same visual direction Rivalry: Competition between the eyes when visual information does not match Suppression: Neurological process of actively inhibiting visual input from part of the vision, typically of one eye

11 Cranial Nerves Involved in Eye Movement CN III Palsy Signs: Lid down, pupil affected, eye down and out CN IV Signs: Head tilt, blurred vision, worse on downgaze, balance CN VI Signs: Worse at distance, cross eyed, head turn

12 What can you observe?

13 Strabismus Assessment Pearls The amount of strabismus can be very small It may not be noticeable Patient may not report double vision

14 What is it like to have strabismus? Normal View

15 Exotropia = double vision & visual confusion

16 Illustration of Vertical Strabismus

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18 Reports Blurry Vision Closes one eye Dizziness and Imbalance Avoids Participating Tilting/turning head

19 Disadvantages of Patching Appearance ~20 degrees of peripheral vision loss May discourage recovery Affects Spatial Attention Patients are often not satisfied with this approach

20 Other Treatments Prisms Vision Therapy Therapy + Prisms Surgery

21 Prism A mystical optical element splits light into component colors?

22 Ophthalmic Prisms Shift light instead of focusing, color dispersion is minimal Image Apex Light Direction of image shift Base

23 If you look through a prism Image shifted towards apex (thin side) Apex 3.5 deg base down Direction of image shift Base

24 Designs of Prisms: Standard Prism vs. Fresnel Standard Photo illustratio n next slide Fresnel

25 10 degree standard vs. 20 degree Fresnel The Fresnel = an important advance for clinical application of prisms Up to 30 degrees

26 Application for Strabismus Fit over entire lens of one eye to optically align the images seen by the two misaligned eyes. Base Out Base In

27 Prisms Facilitate Fusional Convergence

28 Prisms: An assistive device for Strabismus Reduce the amount of fusional vergence needed Fit over entire lens of one eye to optically align the images seen by the two misaligned eyes. *Prisms for strabismus well accepted in mainstream Ophthalmology/Optometry

29 Important to be aware of side effects All prisms cause chromatic aberration and distortion Press-on prisms cause additional blur (filmy vision) Lessened angle of strabismus is sometimes more bothersome harder to ignore double image This is monitored closely

30 Actual Photo Through a 10 degree Press-on Fresnel Prism View Actual View

31 Spaulding Vision Rehab 1) environmental adaptation & postural adaptation to improve function; 2) neuro-muscular re-education with oculomotor vision therapy to maximize recovery

32 Patient with R CN III palsy: When she looks right (or postures with a left head turn) she gets single vision When she looks left (or postures with a right head turn) she gets double vision

33 Flowcharts for Postural Modifications 3rd Postural adaptations Right Eye Affected Left Eye Affected Turn L Turn R Distance Easier, Move Further Distance Easier, Move Further *Cue to focus hard to eliminate diplopia Right Eye Affected 4th Left Eye Affected Bring reading material up &/or tilt chin in Tilt head L Tilt head R 6th Right Eye Affected Left Eye Affected Turn R Turn L Move Closer Move Closer *Cue to relax gaze to eliminate diplopia Turn head L Turn head R

34 Our eyes moves naturally, isn t that enough? Avoidance with head posture Disuse syndrome of ocular muscles No attempted vergence Atrophy eventually *Disuse is not referring to amblyopia. Not a concern in adults. Disuse refers to avoid making eye movement into paretic field

35 Vision Interventions 3 rd Nerve 4 th Nerve 6 th Nerve Binocular Impairments Hemianopia

36 Vision Exercises Oculomotor strengthening Improve fusion/single image Improve vergence

37 Pursuits Oculomotor Strengthening O, X, H Saccades Thumb saccades

38 Alternate Cover, Cover-UnCover Stabilize head in straight ahead position and look at target (smaller targets are more difficult) Alternate covering each eye several times while looking at a target Uncover both eyes and try to fuse into one image

39 Head Turns Look at target (starts as double) and slowly rotate head to move images closer together to become single Check the postural modification cheat sheet To determine which direction should lessen the misalignment

40 Vestibulo-Ocular Reflex

41 Vergence Exercises Pencil Push Ups Brock String Fusion Cards Divergence Convergence _sizedist&ttl=size%20and%20distance

42 Brock String Convergence or Divergence: Moving the x of the string closer and further away Slow: slowly move the bead toward or away from the nose Fast: jumping between looking at several beads /Brock-String-Devices

43 Free-space Fusion Cards Lifesaver cards

44 Protocols: Oculomotor Therapy Bottom Up Top Down Vestibular Ocular Reflex Retinal Disparity/Refixation Motor Priming Volitional FEF to brainstem Repetitive Head Rotations Single to Double Alternate Cover Repetition Repetitive Saccades (Head Stabilized) OCULOMOTOR THERAPY GOALS: 1) Maximize Neuromuscular Recovery 2) Prevent Disuse Atrophy 3) Prevent Contracture 4) Motor Adaptation 5) Recruitment 6) Psychological Benefit

45 Frequency Wear prism glasses as often as possible Exercises ideally 3 sessions per week for 30 minutes each 2 minute minimum per task or reps

46 Ensure binocularity Troubleshooting Are they blocking or closing one eye? Make sure both eyes are fixating Watch for suppression Avoid Compensation Are they rotating their head when it should be stable? Find the best position before starting Examples: Establish sight of a single pencil before bringing it closer Adjust head, string or bead position until they see the x of the brock string

47 Questions?