For those who have experienced any type of head trauma that results in a concussion or post-concussion syndrome, you probably are well aware that there can be numerous eye-related problems that result. Eye symptoms are a frequent side effect of a concussion, and studies have found that vision problems may affect 69% to 82% of concussed patients, regardless of age. Among adolescents, nearly half had been clinically diagnosed with more than one eye symptom as result of their concussion.1-2
The most common eye problems include:
- Blurred or double vision
- Sensitivity to light and photophobia
- Partial vision loss
- Eye or ocular pain
- Abnormal eye movements
- Visual motion sensitivity
- Vertical heterophoria
Some of these may directly affect ocular function while others may be part of an impairment with vestibular or neurological systems—which ultimately causes the eye or vision issues. (Think post-concussion headaches which also leads to eye pain and light sensitivity, for example.) Regardless, we explore each of these symptoms in depth below.
Blurred or double vision
Blurry or double vision (diplopia) are a common complaint after a concussion and may result from damage to the muscles and/or nerves around the eye. This can stem from what is known as convergence insufficiency; in effect, the alignment of the eyes diverge when trying to focus on nearby objects. Double or blurred vision after a head injury might also indicate a more serious neurological disorder, such as migraine with aura or migraine-associated vertigo. In addition, this can result in other physiological or cognitive complications such as: dizziness; poor balance; eyestrain; difficulty reading or concentrating.
Light sensitivity and photophobia
Photophobia, or sensitivity to light, is also a residual effect of a concussion and 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 harmful for light sensitivity after concussion. The force of the trauma can cause displacement, irritation, or injury in several pain-sensitive brain-related structures.6-7 This may also explain the high prevalence of concussion-related headache disorders as well, which also can contribute to a person’s sensory sensitivities.
Partial or complete loss of vision can also occur post head trauma, often taking on different forms depending on the patient. For instance, he or she might experience blind spots in the periphery or have reduced vision in one half of the visual field. And it can be caused by several factors. In some cases, direct injury to the eye may be visible and indicated by lacerations, bruising, broken blood vessels, and swelling in the area. Although less common, vision loss can also be neurological in origin—represented by trauma to the main optic nerve in the back of the eye or brain dysfunction that affects the visual pathway.3
Eye (ocular) pain
Sometimes the eyes just hurt, whether it is a stabbing pain, a dull ache in or around the eye, or even redness, burning and itchiness. The trauma that caused the concussion can sometimes create what is known as an accommodation spasm which can make the eye hurt. This is when one of the muscles around the eye contracts and stays contracted for an extended period of time. Other muscle inflammation as well as light exposure (for a photophobic or inherently light-sensitive patient) can also lead to eye pain after a mild traumatic brain injury.
Abnormal eye movements
Weakened, delayed or otherwise abnormal eye movements are also frequently present for patients and are particularly noticeable for those with persistent post-concussion syndrome. The ability to track and focus on moving objects (pursuit eye movements) or scan and shift visual focus from one object to another (saccades) are the most prominent deficits observed by researchers. Gaze stability, which refers to the eye’s ability to maintain focus while the head is moving, can also be brought on by head trauma.4 There are many experts who suggest that these issues are some of the earliest diagnostic markers for post-concussion syndrome or a more severe traumatic brain injury. Unfortunately, ocular issues have been associated with worsening outcomes (like higher symptom burden and impaired daily living) for some post-concussion patients.5
Visual motion sensitivity
Concussed patients often report that they feel disoriented or uncomfortable and/or have other symptoms (e.g. vertigo) triggered by busy or disorienting environments. This is specifically referred to as visual motion sensitivity and is thought to be caused by dysfunction of the central nervous system that limits the patient’s ability to process complex external stimuli.5
Vertical heterophoria occurs when the eyes are misaligned vertically, meaning one eye is usually higher than the other. The eyes will try to compensate which can bring about strain or fatigue in the eye muscles. Vertical heterophoria can also make the patient see double, feel dizzy, or experience headaches or eye pain. Although it is unclear if mild traumatic brain injuries directly lead to it, experts believe it can be made worse by a head injury.
1 Gallaway M, Scheiman M, Mitchell GL. Vision Therapy for Post-Concussion Vision Disorders. Optom Vis Sci. 2017 Jan;94(1):68-73. doi: 10.1097/OPX.0000000000000935.
2 Master CL, Scheiman M, Gallaway M, Goodman A, Robinson RL, Master SR, Grady MF. Vision Diagnoses Are Common After Concussion in Adolescents. Clin Pediatr (Phila). 2016 Mar;55(3):260-7. doi: 10.1177/0009922815594367. Epub 2015 Jul 7.
3 Atkins EJ, Newman NJ, Biousse V. Post-Traumatic Visual Loss. Reviews in neurological diseases. 2008;5(2):73-81.
4 Broglio SP, Collins MW, Williams RM, Mucha A, Kontos A. Current and emerging rehabilitation for concussion: A review of the evidence. Clinics in sports medicine. 2015;34(2):213-231. doi:10.1016/j.csm.2014.12.005.
5 Heitger MH, Jones RD, Macleod AD, Snell DL, Frampton CM, Anderson TJ. Impaired eye movements in post-concussion syndrome indicate suboptimal brain function beyond the influence of depression, malingering or intellectual ability. Brain. 2009 Oct;132(Pt 10):2850-70. doi: 10.1093/brain/awp181. Epub 2009 Jul 16.
6 The Impact of LCD Screens on Post-Concussion Syndrome. 1 Aug 2017. Retrieved from www.theraspecs.com/blog/lcd-screens-post-concussion-syndrome.
7 Digre KB, Brennan KC. Shedding Light on Photophobia. Journal of neuro-ophthalmology : the official journal of the North American Neuro-Ophthalmology Society. 2012;32(1):68-81. doi:10.1097/WNO.0b013e3182474548.