Photophobia or photosensitivity, is one of the more common conditions associated with a traumatic brain injury, experienced by approximately 50% of patients.
One of the most common symptoms reported after a head injury is photophobia or light sensitivity. This is experienced both by those who have had a serious head injury (TBI or traumatic brain injury) as well as a mild head injury (mTBI).
Mild TBI (mTBI), which is typically defined by Glasgow Coma Scale score ≥ 13, accounts for the vast majority of all TBIs, particularly in the setting of sports-related injuries. The Glasgow Coma Score is a method for assessing the patient's extent of consciousness after a traumatic brain injury.
A mTBI can result in a variety of visual complications. These are some of the most common visual-related conditions and symptoms:
The conditions described above are in some way related to one another. There is a link between convergence problems and accommodative problems, for example. Another example is headaches and photophobia. Post Traumatic Vision Syndrome was described by William V. Padula, OD, as a cluster of vision and spatial disorders that affect people who have suffered a neurological event, such as a traumatic brain injury, a cerebral vascular accident, multiple sclerosis, or another neurological disorder.
If you are experiencing any of the above symptoms and conditions following a traumatic brain injury, you don't have to suffer any longer. It is possible to alleviate these symptoms with a customized neuro-optometric rehabilitation plan and continue to do your everyday tasks without difficulty and sensitivity to light.
Often, when the visual system isn't functioning appropriately after a neurological/traumatic injury, we see a high level of exophoria (one eye drifting out) or exotropia (eye misalignment where one eye deviates outwards). Due to this additional effort, the visual system is stressed and activates the proprioceptive fibers in the extraocular muscles, which transmit signals to the trigeminal ganglion indicating the added effort. Nerve signals sent to the trigeminal ganglion activates pain signals through the thalamus and up to the cerebral cortex. Patients may experience headaches, light sensitivity, or dizziness.
Photophobia is closely linked to pain sensation. It is the trigeminal nerve and its nuclei that are responsible for sensations of pain in the head. Several parts of the eye are densely innervated with trigeminal fibers and sensitive to pain, including the conjunctiva, cornea, sclera, and uvea (iris, ciliary body, and choroid). Photophobia is usually caused by painful stimuli to these areas (e.g. corneal abrasion, iritis, uveitis).
On a pathophysiological level, let's examine some of the more common mechanisms. The retina contains photosensitive cells known as rods, cones, and intrinsic photosensitive retinal ganglion cells (ipRGCs). In the human retina, rods and cones are the predominant photosensitive cells. Melanopsin is found in the intrinsic photosensitive retinal ganglion cells. These cells specifically detect luminance levels, but they do not support vision. The ipRGC sends axons to the suprachiasmatic nucleus of the hypothalamus, and these axons control circadian rhythms. In addition, the ipRGC cells also send axons to the Edinger-Westphal nucleus to control the pupil light reflex. In the human retina, there are only 3,000 of these cells, representing .2% of all RGCs. These cells are photoreceptive, with maximum sensitivity to blue light within the 460-480 nm range. A patient with a traumatic brain injury may have a poorly regulated melanopsin-signaling system when exposed to light.
In patients with photosensitivity, visual fields are important. It was noted by Christine T. Langerhorst and Avinoam B. Safran that there were generalized constrictions in the visual field. While the authors attributed it to an attention disorder, Jackowski attributed it to loss of rod-mediated activity related to dark adaptation. All patients reporting photosensitivity had visual field losses within the central 30 degrees when Jackowski used frequency doubling technology (FDT). Rods affect magnocellular loss, which affects the FDT. These patients reported collapsing visual fields during testing. Kinetic fields, such as Octopus or Goldmann, can also be used to map the visual field constriction. It was found that the FDT and kinetic fields show a strong correlation with visual field constriction.
The degree of light sensitivity caused by mTBI varies from mild to severe. The most severe cases might require patients to wear sunglasses constantly, even indoors. They may be sensitive to fluorescent lighting as well as digital devices, which emit a lot of blue light. With the introduction of filters and vision rehabilitation, light sensitivity can be improved even when it is severe and of long duration.
The goal is to relieve symptoms with specific filters and to take the patient off the use of sunglasses indoors. Photosensitivity is associated with visual fatigue. It often occurs in conjunction with binocular vision problems, and is not a standalone condition. Binasal occlusion is used to reduce binocular stress in patients with mTBI. Through binasals, the system becomes less hyper-focused, which reduces sensitivity to light. Additionally, blue filters may reduce symptoms of indoor light sensitivity. Polaroid, blue-blocking filters, and FL-41 filters can be used outdoors to tone down the brightness.
Photophobia is a complex subject. Research in the future will provide us with a deeper understanding of photophobia in mTBI patients and allow us to provide better treatment for them.
If you don’t already have a trusted optometrist, you could start your online search by typing in phrases such as "eye doctor near me," "optometrist near me," or "eye specialist near me."
Photophobia or light sensitivity is one of the most common symptoms reported following a mild or severe traumatic brain injury (TBI). A range of visual complications can occur after a TBI, including oculomotor dysfunction, dry eye, photophobia, disorientation, dizziness, and sleep disorders, with photophobia being experienced by around 50% of patients. TBIs can affect visual ability, often causing high levels of exophoria or exotropia, which can trigger pain signals leading to headaches, light sensitivity, or dizziness. Photophobia is connected to the pain sensation, caused by painful stimuli to areas of the eye innervated with trigeminal fibers. TBIs can cause a poorly regulated melanopsin-signaling system, triggering light sensitivity. Patients with photosensitivity often experience visual field losses. Treatment for light sensitivity varies based on severity and can include filters, vision rehabilitation, and use of sunglasses. In the future, further research will enhance our understanding and treatment of photophobia in TBI patients. If you're looking for an eye doctor, use online search terms like "eye doctor near me" or "optometrist near me."