Traumatic and Acquired Brain Injury TBI

What is Acquired Brain Injury (ABI) or Concussion?


Acquired Brain Injury (ABI)/concussion is an all-encompassing/umbrella term for damage to the brain that occurs after birth. Typically this damage is sudden, non-progressive, non-degenerative, and leads to abnormalities in neurological processing. These neurological changes can adversely affect the way a person functions in their activities of daily living, i.e., thought process, emotional behavior, speech ability, and physical changes such as impaired motor function, problems with a person’s visual system including, but not limited to:

  • Eye tracking problems
  • Eye teaming problems
  • Eye focusing problems
  • Visual field problems
  • Visual information processing problems

An ABI can be from an external traumatic injury (where the brain encountered physical trauma from such incidents as a motor vehicle or bicycle accident, a fall, an assault, contact sports, or neuro-surgery, etc.) or it can be from an internal cause (a stroke, an aneurysm, a brain tumor, a viral infection or inflammation such as meningitis, a vestibular dysfunction such as Ménière’s disease, or any post-surgical complications leading to an anoxic or hypoxic event in the brain).

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How can this affect my vision?

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(Image provided by NORA –

The majority of the hardwiring of the brain involves the visual pathway, so it is common to experience a visual problem after a brain injury. The most common visual symptoms/visual problems associated with acquired brain injury (ABI) are:

  • Blurred vision at distance viewing
  • Blurred vision at near viewing
  • Slow shift of focus from near-to-far or far-to-near
  • Difficulty copying or taking notes
  • Double vision
  • Pulling or tugging sensation around eyes
  • Unable to sustain near work or reading for periods of time
  • Loss of place while reading
  • Eyes get tired while reading
  • Headaches while reading
  • Covering/closing one eye
  • Easily distracted when reading
  • Decreased attention span
  • Reduced concentration ability
  • Difficulty remembering what has been read
  • Loss of balance
  • Face/head turn or head tilt
  • Bothered by movement in environment and/or by crowded environments
  • Light sensitivity
  • A sensation of the floor, ceiling, or walls tilting
  • Dizziness
  • A sensation of the room spinning
  • A sensation of not feeling grounded
  • Postural shifts/veering off when walking

Neuro Optometric Vision Rehabilitation (Brain Injuries & Vision)

How vision affects learning and concussion recovery

Other visual conditions that can develop at birth or due to a brain injury:

  • Nystagmus- a vision condition in which the eyes make repetitive, uncontrolled movements. These movements often result in reduced vision and depth perception and can affect balance and coordination. These involuntary eye movements can occur from side to side, up and down, or in a circular pattern (
  • Oscillopsia– a phenomenon where images are perceived as unstable and moving, and is the result of ocular instability. This condition is usually associated with acquired nystagmus, or lesions in the oculomotor, cerebellar, and vestibular systems. Patients with oscillopsia usually report blurred vision, images go in and out of focus, double , nausea, dizziness and challenges with activities of daily living.
  • Visual Snow Syndrome (VSS) – is a rare condition where patients complain of visual snow or dots appearing in their field of vision or appearances of static like in a poorly tuned television. Some patients also report palinopsia (images at times superimposed on the new image, and frequently with trailing), entopic imagery (persistence of an image), light sensitivity, hyperacusis, impaired night vision, phonophobia, imbalance, and/or tinnitus.

Here are some visual symptoms to look out for:

Post-Trauma Vision Symptoms

  • Double vision
  • Headaches
  • Blurry vision
  • Dizziness or nausea
  • Attention or concentration difficulties
  • Staring behavior (low blink rate)
  • Spatial disorientation
  • Loses place when reading
  • Can’t find beginning of next line when reading
  • Comprehension problems when reading
  • Visual memory problems
  • Pulls away from objects when they are brought close to him/her

Visual Midline Shift Syndrome

  • Dizziness or nausea
  • Spatial disorientation
  • Consistently stays to one side of hallway or room
  • Bumps into objects when walking
  • Poor balance or posture: leans back on heels, forward, or to one side when walking. standing or seated in a wheelchair

Insults to the cortex produced by a traumatic brain injury cause stress in central and autonomic nervous systems. The effect on vision causes an interference with the ambient visual process which is part of the sensory-motor feedback loop. This disruption occurs at the level of mid-brain where vision is matched with kinesthetic, proprioceptive, and vestibular processes. As a result, a head injured person may experience diplopia (double vision), binocular dysfunction, or concentration difficulties.

In the past, these symptoms were diagnosed as individual eye problems or muscle imbalances. However, the visual system is really a relationship of sensory-motor functions which are controlled and organized in the brain. The eye alignment imbalances and other reported difficulties that result from a head injury often occur because of dysfunction of the ambient visual process affecting sensory-motor spatial disorganization. This causes an eye to turn out (exotropia) or a strong tendency to both eyes to diverge (exophoria).

The resulting binocular problems are characteristics of a syndrome – Post Trauma Vision Syndrome (PTVS).

What treatments are available?

  • Lens – a specifically prescribed optical device that focuses light onto the retina to obtain a clear image; at times, lenses are used at near to help the eye focus more easily and efficiently with increased comfort.
  • Prism – a specialized optical device that deviates/’bends’ light; prisms are frequently prescribed as a component of the treatment for binocular vision problems and to eliminate double vision, as well as to provide comfort for near visual tasks such as reading.
  • Tint/coating – an optical component that alters the amount of light to the eyes; at times, it may also alter the color of the object; they are used to help those with light sensitivity/glare problems.
  • Selective occlusion and/or Binasal Occlusion – the use of specially graded filters to help patients who are experiencing double vision or visual confusion, to provide visual comfort and improve central-peripheral awareness.
  • Neuro-Optometric Rehabilitation (Vision Therapy) – is a series of vision therapy sessions, similar to physical therapy, to train the brain and eyes to work together as a team and to improve visual skills, visual spatial awareness and reduce visual symptoms.

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Further Readings from NORA Regarding Concussions and Brain Injuries:

Common Vision Problems & Symptoms Following a Concussion
Neuro-optometric Rehabilitation – A Vital Part of Your Overall Recovery
The Vestibular Vision Connection
Women and Concussions

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Demonstration of Oculomotor-based Reading Dysfunction on the overall reading eye movement pattern and reading efficiency

Conceptual Model of Optometric Vision Care in Mild-Traumatic Brain Injury

Visual Motion Sensitivity in Mild TBI: Concepts and Remediation