A concussion can be caused by direct blows to the head, gunshot wounds, violent shaking of the head, or force from a whiplash-type injury. Both closed and open head injuries can produce a concussion. A concussion is the most common type of traumatic brain injury.
A concussion is caused when the brain receives trauma from an impact or a sudden momentum or movement change. The blood vessels in the brain may stretch and cranial nerves may be damaged.
A person may or may not experience a brief loss of consciousness (not exceeding 20 minutes). A person may remain conscious, but feel “dazed".
A concussion may or may not show up on a diagnostic imaging test, such as a CAT scan.
Skull fracture, brain bleeding, or swelling may or may not be present.
A concussion can cause injury resulting in permanent or temporary damage.
Following a concussion, there is often an interruption in communication between the eyes and the brain. Studies show that at least 50% of Traumatic Brain Injury patients suffer from visual dysfunctions, with one such study finding a 90% incidence of post-trauma visual complications (1).
Some symptoms may only last a few seconds while others can linger for months or years. The Concussion Legacy Foundation and the Neuro Optometric Rehabilitation Association (NORA) put together this list of vision problems and symptoms following a concussion (2):
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.
Eye movements are important in the reading process, as well as tracking moving objects with the eyes, like a ball being thrown.
Recent studies have suggested that LCD screens (such as from computers or smartphone devices) can be particularly bothersome after a concussion.
This can be extremely disorienting and can cause dizziness, difficulty balancing, walking, and reading.
Judgement of where objects are in space; difficulty with eye-hand coordination.
Reduced awareness of objects or people in one’s peripheral vision, being easily startled by things appearing from the side, or a tendency to bump into things that were not seen.
Visual deficits related to a traumatic brain injury should be evaluated by an optometrist who is trained in the evaluation and management of eye and vision complications of concussion. Treatment requires a multi-disciplinary effort, including vision rehabilitation as an important part of post-concussion care. To locate an appropriately trained provider in your area, visit http://www.noravisionrehab.org. For more concussion information and resources, visit http://www.concussionfoundation.org.
Concussions remain one of the most difficult neurological issues to detect and accurately diagnose. Evidence of a concussion may not always be visible on MRI or CT scans, and there is no blood test or saliva test to indicate a concussion.
A doctor may perform neuropsychological tests to determine if you are having difficulty with cognition and memory after a concussion. These tests may also detect any emotional changes. A neuropsychological test may involve answering questions or performing tasks. For example, to test for attention span and memory, the doctor might ask you to repeat a series of numbers, letters, or words. To test for language and speech skills, you might be asked to name the objects in pictures or as many words as you can think of that begin with a certain letter.
New research and new technologies are showing exciting promise in the area of concussion and traumatic brain injury screening and diagnosis. There are eye tracking technologies emerging that are showing early positive results in detection of concussion.
(1) Ciuffreda KJ, Kapoor N, Rutner D, Suchoff IB, Han ME, Craig S. Occurrence of oculomotor dysfunctions in acquired brain injury: a retrospective analysis. Optometry 2007;78(4):155-61.
(2) "Common Vision Problems and Symptoms Following a Concussion" Concussion Legacy Foundation and Neuro Optometric Rehabilitation Association. https://noravisionrehab.org/uploads/media/NORA_CLF_CommonVisionProblems_FINAL_11-18.pdf
(3) “Sports-Related Head Injury” American Association of Neurological Surgeons. www.aans.org/Patients/Neurosurgical-Conditions-and-Treatments/Sports-related-Head-Injury
(4) Master CL, Scheiman M, Gallaway M, Goodman A, Robinson RL, Master SR, Grady MF. Vision Diagnoses are Common After Concussions in Adolescents Clin Pediatr (Phila). 2016 Mar;55(3):260-7. doi: 10.1177/0009922815594367. Epub 2015 Jul 7
(5) Phil Veliz, PhD et al. Prevalence of Concussion Among US Adolescents and Correlated Factors. JAMA, September 2017 DOI: 10.1001/jama.2017.9087