Concussions
Approximately 4-5 million concussions occur annually, which makes concussion the most common type of traumatic brain injury.
The majority of concussions are caused by a blow to the head (blunt trauma). The most common cause of concussions in children is sports, specifically contact sports such as soccer, football, hockey and lacrosse. Concussions may also be a result of violent shaking of the head or upper body; direct contact in the form of a “bump of the head” is not required to cause a concussion.
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Motor vehicle accidents and falls are the most common causes of concussions in adults. Seemingly mild “bumps on the head” can have drastic neurological effects, which can in turn affect the visual system, making daily tasks such as reading or driving extremely difficult (if not impossible).
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If you had one concussion in the past, you are more susceptible to another.The increased risk of repeat concussions is one of several reasons why the decision to return to play, to work, or to school should be made with your health care team.
Some symptoms of concussion are physical symptoms, such as a headache or vision problems. Others are cognitive, such as feeling ‘in a fog’ or visual perceptual challenges. Still others are emotional, and sleep can also be affected. The multitude and variability of concussion symptoms make medical evaluation very important following a concussion.
Approximately 70% of the neural connections within the brain are involved with some aspect of vision, whether it is visual input, visual perception, or visual integration. This being the case, it is not surprising that vision problems are so common following a concussion/acquired brain injury.
There are several potential visual side effects of a concussion that are consistent with other forms of mild traumatic brain injury. Concussions can have the following adverse effects on the visual system:
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Accommodative Insufficiency
This condition is a reduction in eye focusing ability that results in blurry vision at near. Near vision blur may be constant or intermittent during near activities like reading.
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Blurry Vision
Blurry vision can occur at distance, near, or both following a concussion.
Convergence Insufficiency – This is the inability to use the eyes comfortably in near activities, resulting in a number of symptoms including headaches, eyestrain, fatigue, or even double vision.
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Diplopia
There are several causes of diplopia, or double vision. Anyone who sees double (even intermittently) should be evaluated by a developmental optometrist with advanced training in binocular vision and vision therapy.
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Photophobia
This is light sensitivity, a common result of various types of acquired brain injuries (including concussions).
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Ocular-Motor Dysfunction
Deficiencies in eye tracking abilities are very common following concussions and other forms of acquired brain injuries. These eye tracking challenges impact many daily activities, including reading and driving.
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Visual Perceptual Deficits
These include challenges in several visual/cognitive areas including visual discrimination and visual memory, and have dramatic effects on academic and even athletic success.
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Reduced Reaction Time
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Prolonged visual processing speed can slow down reaction time of an athlete (both on and off the field), a student, or a driver. The speed with which a person processes visual information affects many aspects of field competition, learning, and safety including ‘reading the field’ of sport/freeway/classroom, judging the speed of a moving ball/car/player, and judging the depth where any action is taking place.
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Some of these symptoms improve with time, others may be unchanging, while others respond very well to active treatment. The good news is that some of the most common visual effects of concussion or mild traumatic brain injury (accommodative insufficiency, convergence insufficiency, and ocular-motor dysfunction) are all conditions that respond to vision therapy.