Vision Deficits After TBI

1. Vision Deficits After TBI Presented by: Carl Garbus, O.D., FAAO

2. Learning Objectives • Describe the incidence and prevalence of brain injury • Distinguish between acquired brain injury and traumatic brain injury • Identify basic brain structures and functions • Describe 2 main visual processes in the brain • Describe visual consequences of brain injury • Discuss assessments and interventions

3. Goals for the Presentation • Create awareness of what to look for in patients who have had traumatic brain injury • Stress the importance of having a neuro vision evaluation for patients with traumatic brain injury and stroke • Know that neuro vision rehabilitation exists for patients with these conditions

4. Definitions Acquired brain injury (ABI) – • An injury to the brain that has occurred after birth and is not hereditary, congenital or degenerative. • The term does not refer to brain injuries induced by birth trauma.

5. Causes of ABI • Traumatic brain injury (TBI) • Strokes • Tumors • Blood clots • Seizures

6. Causes of ABI • Toxic exposures (substance abuse, ingestion of lead, inhalation of agents) • Infections (encephalitis, meningitis) • Metabolic disorders (insulin shock, diabetic coma, liver and kidney disease) • Neurotoxic poisoning (airway obstruction, strangulation, carbon monoxide poisoning) • Lack of oxygen to the brain

7. Definition Cerebral Vascular Accident (CVA) • Stroke - A stroke occurs when a blood vessel that carries oxygen and nutrients to the brain is either blocked by a clot or bursts. When that happens, part of the brain cannot get the blood (and oxygen) it needs, so it starts to die.

8. 2 Types of Stroke 1. Ischemic strokes occur as a result of an obstruction within a blood vessel supplying blood to the brain. The underlying condition for this type of obstruction is the development of fatty deposits lining the vessel walls. This condition is called atherosclerosis. (87%)

9. 2 Types of Stroke 2. Hemorrhagic strokes result from a weakened vessel that ruptures and bleeds into the surrounding brain. The blood accumulates and compresses the surrounding brain tissue. The two types of hemorrhagic strokes are intracerebral hemorrhage or subarachnoid hemorrhage. (13%)

10. Definitions Traumatic brain injury (TBI) • An insult to the brain, not of a degenerative or congenital nature but caused by an external physical force, • That may produce a diminished or altered state of consciousness.

11. Causes of TBI: • Motor vehicle accidents - whiplash • Falls • Gunshot wounds • Work place injuries • Shaken baby syndrome • Child abuse • Sports injuries • Military actions

12. Statistics • An estimated 1.7million people sustain a TBI annually in the US. • 52,000 die • 275,000 are hospitalized • 1.365 million, nearly 80%, are treated and released from an emergency department.

13. Different ways brain can be damaged

14. Neck Trauma • Whiplash: • A simple whiplash can cause shearing of nerve fibers in the brain stem • This can occur from being rear ended by a car driving moving at 15 miles an hour • Disruption of fibers in the brainstem affects oculomotor and binocular functions.

15. Whiplash Injury

16. Basic brain structures and functions Lobes

17. " The eyes see only what the mind is ready to comprehend" Henri Bergson

18. Brain and vision: the connection • Every lobe of the brain is involved in processing visual information. • To date, researchers have identified over 300 intracortical pathways linking 32 different cortical areas involved in vision function. • More than half of our gray matter and multiple subcortical areas are involved in processing vision. • There is more area of the brain dedicated to vision than to all the other senses combined.

19. The Visual Brain

21. Visual SystemGeneral Overview • 70 % of all sensory processing in the entire body is directly affected by information coming from the two eyes • Optic Nerve- 1,000,000 nerve fibers per eye • There are several important pathways where the visual information travels • Brainstem – Cranial Nerves 8 of 12 relate to the visual system

22. Vision is a Bimodal System • There are 2 main pathways that carry visual information from the eye to the brain. • Focal - the "what" system • Ambient - the "where system" • Designed to simultaneously process different types of visual information • Neither works in isolation of the other; both reinforce one another

23. Focal and Ambient Systems • Need to work in harmony • They are not isolated systems • A disconnect in the ambient system will cause problems with spatial orientation • Symptoms include: balance problems, bumping into things, difficulty navigating

25. Five Pillars of Function • Visual • Physical / Vestibular • Somatosensory • Cognition • Psychosocial

26. Why is vision rehabilitation so important following brain injury? • Vision is our dominant sense; we are visual beings. • Vision is pervasive throughout our brain. • Vision is represented all over our body. • Vision influences and influenced by anything and everything - the way we think, say, or do. • Visual problems are among the most common consequences of TBI and or CVA but frequently not dealt within rehab model.

27. Visual Consequences of TBI: Post Trauma Vision Syndrome (PTVS) • A constellation of symptoms that evolves as secondary injury in TBI. • This syndrome is caused by a dysfunction of the ambient visual system and has the characteristics listed below: • Binocular coordination dysfunctions - double vision • Inability to perceive spatial relationships between objects • Difficulty fixating on object and following when it moves • Abnormal posture • Dizziness and balance problems • Poor visual memory

28. Visual consequences of TBI: Post Trauma Vision Syndrome (PTVS) • Poor concentration and visual attention • Difficulty with visually guided movements (bumping/tripping, knocking things over) • Light sensitivity / photophobia • Visual midline shift syndrome • Visual spatial difficulties

29. What are the functional implications?Light sensitivity

30. What are the functional implications? Visual Field Defect

31. Sense of balance • Bump into things • Difficulty with eating • Slow reading

32. What are the functional implications? Binocular Dysfunction

33. Difficulty judging distance or depth • Tendency to knock things over • Bump or trip over obstacles • Difficulty playing sports

34. What are the functional implications? Visual information processing

35. Avoidance of crowded or busy places • Short memory • Forget familiar route • Slow to process

36. Visual Midline Shift • Mismatch between the perceived egocentric visual midline and the actual physical midline • Causes an expansion on one side • Causes a contraction on the opposite side

37. Visual Midline Shift Syndrome Signs and Symptoms • Floor may appear tilted • Walls and/or floor may appear to shift and move • Veering during mobility • Person leans away from the affected side • Feelings of imbalance or disorientation similar to vertigo

38. Visual Spatial Inattention • Individual with TBI or Stroke does not process information on one side of their body • Also known as Visual Neglect or Hemi-neglect • This is not a field defect but it can exist with a field defect • In severe cases the patient is not aware of a body part

39. Visual Spatial Inattention Copying

40. Star Cancellation

41. Cranial Nerve VIII – Auditory and Vestibular Nerve • Nerve that transmits information for hearing and balance

42. Vestibular Function • The visual system links up very closely with the vestibular system in the brainstem and midbrain • Vestibular –Ocular Reflex (VOR) is activated when there is a head movement, body movements or if the individual leans to one side

43. Vestibulo-Ocular Reflex • Maintenance of fixation of the eyes with head movements • It is activated with horizontal and vertical head movements • This intricate system links the vestibular system to the oculomotor system

44. Interventions • Patient education • Explain brain and vision relationship • Review individual's specific diagnosed eye condition in plain language • Why and how vision may be interfering or limiting daily functions. • Always include family members whenever possible

45. Interventions • Compensation strategies • Relieve visual discomfort from eye strain and fatigue often leading to headaches. • Take care of those dry eyes! • Remediate glare and light sensitivity - very important! • Take frequent breaks from visually demanding tasks - 20/20/20 rule

46. Strategies for Double Vision Techniques • Consult with an optometrist or ophthalmologist who has experience with brain injury • Provide a translucent patch (not dark opaque patch) • Spot patch • Sector patch • Binasals • Active therapy prescribed by the eye care practitioner can improve binocular function- Eye Stretches, Tactile Control, Spatial Localization, Brock String

47. Interventions • Prisms: bends light towards the base, which causes the image to move in the opposite direction---- has implications to change spatial orientation and eye alignment • Lenses: optical correction of refractive conditions helps to locate objects in space and helps with visual comfort • Filters: blocks specific light frequencies that cause visual discomfort which can improve visual performance

48. Summary • Consult with an vision rehabilitation doctor to collaborate about functional treatments • Consider visual conditions that can be treated such as light sensitivity, visual balance, visual midline shift and post trauma vision syndrome • Brainstem damage will have visual and vestibular consequences • Double vision is common problem that needs to be dealt with early

49. Neuro Optometric Rehabilitation Conference • 24th Annual Multi-disciplinary Conference • Renaissance Hotel • May 14-17, 2015 • Denver, CO • Website www.nora.cc