2018

53

Issue

Post Concussion Vision Syndrome

Vision is a dynamic interactive A strong jolt to the torso or neck can also BUT skills have also been noted process of motor and sensory result in the impact ‘radiating’ up into the as an important factor as well. function mediated by the for the brain and still causing the movement The damage to the brain with a purpose of simultaneous organisation inside the skull needed for a concussion. concussion isn’t demonstrable with of posture, movement, spatial The movement of the brain causes modern day imaging so diagnosis and orientation, manipulation of the damage that changes how brain cells improvement is often tracked based environment and, to its highest function, leading to symptoms that can on symptoms. degree, and . be physical, cognitive or emotional. Common symptoms following a When vision is working well, it guides The rate of concussion in New Zealand is concussion are; and leads; when not it interferes. increasing every year. The cost to ACC in Headache is a measure of how the 2012-2013 year was $66.5 millions. clearly we see things but visual Within 4 years that figure increased to Brain Fog, Inattention processing is about accurate input of $88 millions and there were almost 5000 Dizziness the visual information, with more concussion injuries lodged with Nausea integration of sensory and ACC. proprioceptive information. These Figures from the USA show that people Emotional Issues/Mood changes combine to influence and ultimately who are at high risk of suffering a issues guide motor output. concussion are those who have had a Sleep Problems The eyes see things in 2D but the concussion within the previous six brain sees things in 3D. months and, interestingly, teenage girls. Light Sensitivity In high school sports in the USA the Concussion is a brain injury caused by The eyes are the tip of the iceberg second most common group presenting movement of the brain within the when it comes to vision. They are the with a concussive injury are female skull either by direct blow to the receivers, but the brain is the soccer players. This is staggering in a so- head, face, neck, or elsewhere on the processor and the most important called ‘safe’ sport. body with an ‘impulsive’ force part of the visual process. transmitted to the head (whiplash Recent literature suggests the high risk of 80% of fibres go to the effect). teenage girls suffering a concussion is for higher order multifactorial and can be related to It is important to note that not all processing. That leaves 20% that go differences in musculature and skull patients who suffer a concussion will to other parts of the brain, 18% goes thickness in comparison to boys. report a direct blow to the head. to the midbrain (superior colliculus) for spatial orientation and 2% travel to other areas such as the amygdala and hippocampus to regulate body The rate of concussion in New Zealand and mind functions. is increasing every year.

New Zealand Association of Optometrists. PO Box 51008, Tawa, Wellington 5249. [Tel 04 473 2322 www.nzao.co.nz] Occipital lobe injuries are an obvious brain injury to Cognitive/Fatigue– Decreased concentration, affect the visual processing cortex but other areas of difficulty or retaining new the brain can also have a visual outcome. information and increased fatigue as the day progresses The superior colliculus co-ordinates eye movements in relation to the body and the head. It receives Vestibular – Balance centre – can affect the ability information for this task from both auditory visual to interpret motion and co-ordinate head cues along with information from the spinal cord and and eye movements or stabilize vision cerebellum. with head movement The posterior parietal cortex is involved in mapping Ocular – Difficulty tracking or moving one’s eyes where you are in space and helps with and Post Traumatic Migraine– Headaches, nausea hand-eye co-ordination. The frontal lobe is critical in and sensitivity to light or noise executive function and initiating eye movements. Cervical – Can get ongoing headaches The cerebellum is involved in refining and is also important for balance and equilibrium. Anxiety/Mood – Anxiety and trouble turning off Injuries to the brain stem can cause severe light sensitivity. Visual Assessment The pulvinar is important in the initiation of saccades Visual Acuity and Refraction: and visual attention as it has input from the visual Small refractive errors can be much more important cortex, superior colliculus and posterior parietal to correct in a post concussive patient than normal. A cortex that strengthens the visual link. patient who could tolerate low amounts of myopia (-0.50) or hyperopia (+0.50) before a brain injury may Studies vary but anywhere from 50-90% of individuals no longer be able to cope with this after a concussion. have a visual dysfunction after a TBI. The most Often such people benefit from visual correction. common visual symptoms following a concussion are; Visual Acuity is one of the most important visual skills, Blurred Vision 46% such that it can impact on the function of other Double Vision 30% processes such as ocular motilities, accommodation Headaches 13% and binocularity. It forms the foundation of visual processing. Defects 35% It is important to note that the majority of patients Cranial Nerve Palsy 33% who suffer a concussive head injury do not show a reduction at all in their visual acuity. It is for this Visual symptoms can often be non-specific and reason that often vision isn’t considered an important confused with other symptoms. Whilst most patients part of the rehabilitation process. An examination by don’t often complain of blurry or double vision they an optometrist that focuses on more than just static may comment they struggle to read. There is often visual acuity is important to put all the pieces of the too much visual noise and words can swim around on puzzle together. the page. Other complaints can vary but may include bumping into things, feeling nervous in crowded The neural processing of vision is more than just places, a new dislike for going to the supermarket of letters on a chart and practitioners need to keep in mall and the person may feel like they are falling from mind that even with 6/6 visual acuity other vision time to time. problems may exist.

Symptoms of concussion can often be quantified with the use of questionnaires. These same questionnaires Accommodation/Focusing: are used during treatment to track progress and This is important for clear vision in a dynamic improvement. environment with varied working distances. It is The University of Pittsburgh Medical Centre (UPMC) necessary to measure both the amplitude or amount has six clinical trajectories following concussion. They of accommodation and also the speed and ability of all have visual overlap with their symptoms: the accommodative system to change its focus on objects in different areas of space (distance to near and vice versa). : Spatial Localisation is the reference of a visual sensation to a definite object in space. Accurate It is important to have steady fixation on an object in spatial localization can be tested by having the space to be able to see it clearly. Those patients who patient reach out to touch your finger with their have nystagmus do not have a steady point of fixation finger in different positions in space. unless at their null point. Patients must have normal fixation to be able to have normal higher processing Visual Midline Shift Syndrome is a phenomenon that skills such as saccades and pursuits. results in a shift of the midline for the patient. Their ‘centre’ is different and can result in patients complaining that the floor is tilted, walls can shift and Ocular Motilities: move and the patient leans to the unaffected side to Saccades - These are rapid eye movements that ‘balance’ themselves in their new environment. allow fixation to move between different targets in It can be quite simply tested by asking the patient to space. They are both voluntary and involuntary in identify when the examiner’s finger is in the middle of nature. An example of involuntary saccades would be their vision. reacting to an unexpected stimulus in the peripheral environment such as a bright light or a loud bang. A voluntary saccade is the type of eye movement Treatment required for reading jumping between words. Spectacles:

Pursuits - These are smooth eye movements Low prescriptions or prescription changes should be primarily used for tracking. dispensed as needed. Yoked prisms can also be used – the concept behind Binocularity - This is the ability of the to these is to help to expand the space for the patient. have two eyes maintaining fixation on a target that Tints can also be used to help with light sensitivity results in single vision without suppression. Important and calming the visual stimulus. skills to assess in this area are (3D), near point of convergence and vergence reserves (range of Binasal Occlusion is also used: disparity in image location before diplopia appears). The reason this helps is unsure but it is thought it works by limiting the overlapping visual areas Convergence Insufficiency- This is the most between the two eyes until better binocularity is commonly noted sign of post concussion vision achieved. syndrome. It results in an inability of the two eyes to Neuro-Optometric Rehabilitation: converge to read up close. This lack of ‘team work’ results in a loss of binocularity. The eyes are Vision Therapy can be very successfully used to help misaligned and result in eyestrain, headaches and improve the following areas - blurry vision. Visual Function The Convergence Insufficiency Treatment Trial (CITT) Oculomotor (accommodation, binocularity) showed the best treatment for this deficit is in-office Motor Function supervised vision therapy with home exercises also Bilaterality (eye-hand co-ordination, balance) prescribed. 75% of patients in the CITT study receiving Attention (especially visual attention) this treatment had either full correction or marked Central-Peripheral Integration improvement in 12 weeks. Ability to filter and integrate multiple stimuli Given the high demand on our near vision in our day to day life, and with an increased reliance on devices, The point of vision therapy for these patients is to this is a critical area to diagnose and treat. improve accommodation and convergence skills,

facilitate anti-suppression, ensure smooth ocular Other areas that can be assessed are; movements and enhance peripheral vision. Spatial Localisation It is important to concentrate on these skills monocularly before proceeding binocularly. Each eye Visual Midline must be able to contribute equally to the activity for Visual Attention symptoms to resolve. Sideline testing

The King Devick test is designed to test the speed The concept behind the strict testing protocols is that and accuracy of saccadic eye movements. It is a test no matter who the practitioner, results are that has long been used in for that comparable based on the score at each visit. purpose but more research is coming to light of its benefits in sport at the sideline to help make a Neuro-Optometric Rehabilitation is a useful tool in ‘remove from play’ decision. It takes less than 1 what should be a multi-disciplinary approach to minute to administer and baseline tests are concussion and other traumatic brain injury rehab. compared to a test after a potentially concussive There is no one fix for these patients in any event. If the time taken to complete the post-event profession and each patient presents a new of test is 5 seconds longer or there are 2 or more errors challenges. made the advice is to remove the player from the Vision therapy is increasingly seen as an area that is field and seek further investigation. important to help these patients on an international The recently created VOMS (Vestibular/Ocular- stage however it is still somewhat under-utilized in Motor Screening) tool is a standardized test for all New Zealand. professions to use in assessing brain injury and to ACC recognizes that optometry is an important compare responses over time. option for concussion rehabilitation and concussion The patient is asked to score headache, brain fog, service providers are able to refer to any nausea and dizziness after each activity. The optometrists (up to 1.5 hours of time) for assessment activities measured are smooth pursuits, horizontal of visual function related to a claimants injury. and vertical saccades, horizontal and vertical Should specialist optometric assessment/treatment vestibular-ocular reflex, near point of convergence be needed then the concussion service provider can and accommodation. request that it be provided under the claimant’s ACC cover.

PRIMARY EYE CARE

«Title» «Initials» «Surname» «Practice Name» «Address Line 1» «Address Line 2» «Suburb/Town» «City/Region» «Post Code»

NZ Association of Optometrists PO Box 51008; TAWA WELLINGTON 5249