Vision is the skill that allows us to see the world around us. When we observe the world, a complex series of processes takes place between the eye and the brain. The eyes take in the information, while the brain is responsible for processing and interpreting it.
When the brain is injured, the ability to interpret visual information can be affected in different ways.
Visual problems following brain injury can affect both the quality of the information received by the brain and interpretation of the information received.
As a result, brain injury survivors can experience a number of different types of visual problems which can range from mild to severe depending on the nature of the injury. As there are such a wide range of different types of visual problems after brain injury, there is no single way of coping with them.
Following the initial vision and neurological examination a treatment plan is developed with a goal of restoring essential visual function. Because every injury is unique, treatments will vary by individual.
Below are some types of treatments:
- Special Prescription Lenses (Glasses) – Lenses can help compensate for damage to the neural system along with enhancing visual clarity and comfort. Lens filters (tints) provide help with light and glare sensitivity.
- Prism Lenses – These are specialized glasses that change the way light enters the eye. 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. In addition, prisms are often used in treating balance issues, a common component in brain injury.
- Patching – Patching one eye or part of the visual field of one eye is sometimes used to help those with double vision. The patch is placed to eliminate the information that results in the double image from coming into the brain. The patch is frequently placed directly upon the lens surface.
- Visual Therapy
SEEING A NEURO-OPTOMETRIST AFTER A BRAIN INJURY
Brain injury can affect a person in many ways. Depending on the extent of the injury, problems with visual information processing may contribute to and/or exacerbate symptoms of things such as eye strain, fatigue, headaches, difficulties with balance and posture, depth perception, and memory loss. Often one type of rehabilitation is not enough to address all of the individual’s needs. An interdisciplinary, integrated team approach can play a vital role in the rehabilitation of patients with concussions, stroke or other neurological deficits.
DIAGNOSING VISUAL PROBLEMS AFTER STROKE OR TRAUMATIC BRAIN INJURIES
Visual problems are often overlooked during initial treatment of a brain injury and in some cases; symptoms may not be present until sometime following the injury. If you notice any changes in your vision following a concussion or some other head trauma, don’t ignore them: Immediately contact your eye care professional. It is important to determine the cause of the vision change. Early diagnosis leads to appropriate treatment and/or referral to a specialist, such as Deidre de Jongh and Carina Janzen, who are Neuro-Optometric Optometrists.
Left untreated, visual system disorders can have serious consequences, such as the ability to organize and make sense of visual information along with poor depth perception and difficulties concerning balance and posture.
Following are some common vision problems that may occur following brain injury or other medical conditions such as a stroke:
MOTION SENSITIVITY – The integration between the vision and balance system can be disrupted, making it difficult to process motion properly. Symptoms can include discomfort and even dizziness when scrolling on a computer screen or phone, or when in busy environments such as grocery stores, social settings, or sporting events.
Symptoms may vary among individuals, but some typical symptoms include:
- VISUAL FIELD LOSS – Partial or complete vision loss can also occur after a head trauma. The area of the brain that has been affected as well as the extent of the damage will determine your field of view. This may cause such problems as bumping into objects, being struck by approaching objects, or sudden falls. Below is a video explaining Hemianopia.
- EYE PAIN AND REDNESS – Whether it is a stabbing pain, dull ache around the eye, or even redness, burning or itching, you may experience eye discomfort following head trauma. Headaches can be long-lasting, even past one year from injury. These symptoms can make it hard for you to carry out daily activities or can cause you to have more difficulty thinking and remembering things.
- SENSITIVITY TO LIGHT – Brain injury is often accompanied by increased light sensitivity and general inability to tolerate glare. Photophobia, or sensitivity to light, can be exacerbated by specific light sources, such as bright sunlight and fluorescent lighting. Recent studies have also suggested that LCD screens (such as from computers or smartphone devices) can be particularly bothersome after a concussion.
Animated images courtesy of Nielsen Vision Development Center (Selma, TX).
OCULAR MIGRAINE SYMPTOMS: generally include a small blind spot (scotoma) that affects your central vision in one eye. This blind spot gets larger, making it impossible for you to drive safely or read with the affected eye.
In some cases, the entire visual field of one eye may be affected. Generally, the episode lasts less than an hour.
VISUAL MIGRAINE SYMPTOMS: can vary, and may include:
- A flickering blind spot in the center or near the center of your field of view
- A wavy or zigzag ring of colored light surrounding a central blind spot
- A blind spot that slowly migrates across your visual field
Visual migraines often appear suddenly and may create the sensation of looking through a cracked window. The visual migraine aura usually moves across your field of view and disappears within 30 minutes.
The symptoms of a visual migraine typically affect both eyes and last 30 minutes or less. A migraine headache may occur shortly after the symptoms of a visual migraine subside or no headache may occur.
If you’re experiencing a blind spot or other visual disturbance and you’re not sure if it’s an ocular migraine or a visual migraine, then cover one eye at a time. If the visual disturbance is occurring in just one eye, it’s likely that it’s an ocular migraine. If it affects both eyes, it’s probably a visual migraine.
But don’t take chances. If you suddenly experience any sort of blind spot in your field of vision, please contact the practice immediately to book an appointment with our Deidre de Jongh to determine if it’s harmless or possibly a sign of something more serious, such as a retinal detachment.
TYPES OF OCULAR MIGRAINES:
This phenomenon can be a little confusing, because the same term is often used to mean different things, some of which are more serious. Let’s take a look at each of the three conditions the term is commonly associated with.
PAINLESS OCULAR MIGRAINE
This type of ocular migraine usually involves a widening blurry spot in your vision, surrounded by bright, flickering lights. Visual disruptions could be the only symptoms, but sometimes they are accompanied by problems with other senses, speech, or motor skills. The effect can be very disorienting, but it should only last a few minutes to half an hour before going away on its own.
Painless ocular migraines might be alarming the first time they happen, but they are usually harmless. If one happens while you’re driving, pull over until it passes. If possible, lie down and relax until it goes away, and it’s worth scheduling an eye exam just to make sure nothing else is going on.
MIGRAINE WITH AURA
Sometimes the same visual disruptions can accompany a migraine headache, usually between the premonitory and peak pain phases of the migraine.
If you experience these types of migraines, see a doctor if you haven’t already. Also be on the lookout for migraine triggers, such as sudden bright light, stress, and certain foods. Oral contraceptives and smoking can be triggers as well.
A migraine aura is a neurological phenomenon most commonly associated with visual disturbances before the onset of a headache. You may see things like zig zag lines, flashing lights, or other visual effects before your migraine begins.
Migraines with aura include additional visual and non-visual symptoms that can provide a useful warning that a headache is on its way.
The visual aura symptoms may include:
- Geometric patterns
- Flashing lights
- Stars and spots
- Zig zag lines
- A shimmering effect (similar to heat waves)
These may appear in the center of your field of vision and gradually spread outward. Some people also experience blind spots or tunnel vision.
The non-visual aura symptoms may include:
- Tingling or numbness in the hands or face
- Dizziness or vertigo
- Muscle weakness
- Difficulty with speech and/or hearing
- A sense of fear or confusion (rare)
- Partial paralysis or fainting (rare)
Auras usually develop over the course of five to 20 minutes and last fewer than 60 minutes. The head pain and other symptoms associated with classic migraines typically come after the aura, but might begin during the auras well.
The cause of migraines with aura isn’t fully understood. Like migraines without aura they are considered a neurovascular disorder. As nerve cell activity increases within the brain, inflammatory chemicals are released, causing swelling of the cranial blood vessels. As the blood vessels swell, they activate the surrounding pain receptors, which ultimately transmit pain signals to the brain.
The most dangerous (but also the rarest) thing “ocular migraine” could refer to is a retinal migraine. A person who has experienced other migraine symptoms could experience repeated, temporary bouts of diminished vision or blindness in one eye. Be sure to see one of our optometrists or your doctor right away if you experience a retinal migraine.
BALANCE, VISION & HEARING WORKING TOGETHER
For most of us, vision is a term used to describe how clear things are. In reality, the impact of vision on our lives is much more profound than just the clarity of the images being perceived. Vision is also connected to our balance system. To maintain balance and navigate space in our physical world, we must organize and integrate information from the visual (eyes), proprioceptive (information perceived through our muscles and joints to tell us where we are in space) and vestibular (inner ears sensing motion, equilibrium and spatial awareness) systems. A deficiency in any of these three vitals systems can have a dramatic impact on the person’s ability to exist in their world.
The intimate relationship between the balance (vestibular/inner ear) and vision begins at birth, as the vestibular system is the only fully myelinated (a protective sheath around the nerve allowing the nerve impulse to move more quickly) and functioning system that we are born with. IWhen we are young, movement guides vision. However, as soon as we develop the necessary visual skills, vision begins to guide balance.
VISION AND THE BRAIN
It is generally thought that between half and two-thirds of the brain is used for visual processing. When our eyes are open, two-thirds of the electrical activity of the brain is devoted to vision (Fixot). Our vision is such a powerful sense that it can override information from the other senses, which is sometimes beneficial and other times detrimental. When the visual system is not working properly, providing incorrect information to other somatosensory systems, it can dramatically interfere with our quality of life. Fortunately, the human brain is able to continuously create new pathways and neurological connections (synapses) throughout our lives, referred to as neuroplasticity. This concept of neuroplasticity is what allows us to develop the necessary control over different sensory systems, so that we may be able to enhance our ability to interact with the physical world, and thus our overall quality of life.
VESTIBULO – OCULAR REFLEX
Dizziness and disequilibrium are often the result of a vestibulo-ocular reflex (VOR) dysfunction (a reflex which coordinates eye and head movement) and an unstable binocular (how well the eyes work together) system (Cohen). A disruption of balance, or just generally feeling off in our movements, is very common after an acquired brain injury. This is due to a disruption in the integration of the vestibular and visual systems. This sensory incoherence is similar to the situation where the sound and the picture on the TV are out of sync. Both the sound and the picture work, and when isolated may even be pleasant to attend to. However, when those systems are used together, with the timing off, there is a dramatically negative response. Fortunately, using the concept of neuroplasticity, the systems can be synced back together! The proper source of this mismatch must be identified first in order to receive proper treatment. Through proper evaluation and skilled vision therapy, we can improve visual deficiencies.
FUNCTIONAL VISION EXAM
A functional vision exam from a Neuro-Rehabilitative, or Developmental, Optometrist is far different than routine eye exams. Beyond ensuring that the health of the eye itself is adequate, and that sight is sharp, a functional vision exam measures a patient’s oculomotor skills, tracking not only their ability to follow a moving target but also their ability to quickly and accurately jump from one target to another. A thorough exam also assesses the patient’s ability to focus on a target, and to use both of their eyes together to maximize their sense of depth. Additionally, we note the ocular alignment at different positions of gaze, including distance and near, as well as under different stressful situations such as cognitive loading. Flexibility is another key component of our vision assessment, as patients should be able to efficiently move their fixation from one target to another (such as a near to far target, and back). After we have established a thorough understanding of how a patient’s visual system is working, we then incorporate movement and cognitive loading into the diagnostic testing. It is important to note how the visual system performs as the vestibular system is activated, as this may give the provider a clue where the disconnect in the sensory integration lies. It is also important to note whether the cognitive processing and visual system can both function at a high level at the same time. Because vision guides most of our activities, including movement, these motor functions must be an essential part of any thorough exam.
We also must ensure that the patient has balance between their central and peripheral vision systems. Similar to the vestibular system, the visual system can be broken down into a central processing system and a peripheral processing system. The central system is used mainly for clarity in order to identify details of an object. The peripheral system is used to initiate spatial localization and to process movement. Many acquired brain injuries can create an imbalance between the two systems, and visual therapy can be used to rebalance the system.
Extensive trial framing is also a part of a thorough exam, as we need to determine the effects that different prisms and filters have on a patient’s performance. Prisms are special lenses that we use to not only bend light, but to alter a patient’s perception of space (Suter). Patients who have had a traumatic brain injury may organize the space around them in a very inefficient and inaccurate way, or they may lose awareness of it altogether. This can cause patients to bump into things regularly, or feel uneasy as they move around. Using prisms at the appropriate time, and with the appropriate instructions, during therapy allows these patients to become aware of their surroundings again, and to reorient their spatial organization. Filters allow us to determine whether adding or subtracting different wavelengths of light will have a positive or negative affect. Some patients can experience a calming effect when exposed to certain wavelengths of light, while other patients may use colored filters for transient activities such as reading on the computer.
Assuming the necessary anatomical structures are adequate within the vision and balance systems, many deficient skills can be enhanced through the efforts of the hard-working patient, with guidance from a skilled therapist. If the patient was determined to have a vestibular-visual dysfunction, a multidisciplinary approach to treatment usually works best, consisting of skilled vision and vestibular therapists. From a visual therapy perspective, therapists look to maximize visual skills while slowly loading the tasks with different sensory-driven concepts.
Neuro-Rehabilitative Optometrists’ therapy protocols generally deal with isolating the specific visual skills first, and enhancing them to the best of the patient’s abilities. The concept of therapy is built around the idea of neuroplasticity. We start with a specific visual skill in mind, and we present the patient with a particular task. As the patient has to figure out how to perform this particular task, they are indirectly enhancing the specific skills necessary to succeed in that task, while broadening their own sense of body awareness. Learning in the neurological sense, or creating new neural pathways, only happens when the patient is presented with an engaging new task they have to adapt to. As the patient’s mastery of a specific visual skill increases, we continue to load the task so the patient is constantly being pushed to new levels of achievement.