POST-CONCUSSION AND ACQUIRED BRAIN INJURY (ABI)
Following a concussion or acquired brain injury (ABI, mTBI), patients may suffer from lingering light and pattern sensitivity, making it challenging to return to normal activities where reading printed and computer-based material is a fundamental requirement for professional and educational success and daily functioning. While some individuals may report no symptoms at all, others may report confusion, headache, decreased balance and vision disturbances including blurry vision, trouble focusing and sensitivity to light.
Fortunately, there have now been several studies reporting that the photophobia and other visual symptoms following a concussion or brain injury may be alleviated by using precision tinted filters.
Visual stress is a condition characterized by a sensitivity to certain visual stimuli, leading to a range of physical and perceptual symptoms, that is alleviated with the use of individually prescribed coloured filter lenses. The intensity of these effects is greater when individuals are sensitive to light, pattern, and contrast, which can lead to cortical hyperactivation. Reading material, printed and on-screen, contains the attributes necessary to elicit visual stress symptoms and can lead to adverse symptoms including lowered tolerance of lights and screens, headaches, eye pain, dizziness, nausea, and illusions of colour, shape and motion in text and the environment.
A 1996 study provided objective evidence for improvement of visual function provided by light-filtering lenses in patients who become photophobic after TBI. Contrast sensitivity testing and assessment of reading rate added objective criteria for the clinical selection of light-filtering lenses in the treatment of TBI-induced photophobia. 
Studies have proposed that the neurological disinhibition, resulting from brain injury, may be responsible for the increased sensitivities.  And this disinhibition is similar to the hyperexcitability of visual stress.
Additionally, recent studies outlined below have reported that precision tinted lenses, or at least a wider range of filter colour options, provided increased visual comfort by reducing sensitivities to lights, improved reading performance, and allowing engagement in medically approved activities while minimizing the risk of symptom exacerbation.
In 2012, an article written by the Chief of Vision Rehabilitation Services at SUNY College of Optometry, and published by the International Brain Injury Association , outlined the visual-vestibular symptoms of ABI including physical and cognitive fatigue, eyestrain, headache, nausea, disequilibrium and an increased sensitivity to motion of visual stimuli (scrolling or quick moving screen images and movements of crowds) It also identified that these are all symptoms associated with visual stress and the hyperexcitement of the visual cortex, a state which has been demonstrated to be calmed and normalized with the application of precision tinted filters. The study concluded that treatment options include individually prescribed coloured filter lenses and that systems such as Colorimetry provide a systematic approach to determining an appropriate tint or coloured lens overlay.
In a further study by the SUNY College of Optometry 2016 , patients used the Intuitive Colorimeter device to select their optimal filter to provide the most comfort and clarity of text. The research team found that most patients with ABI chose a precision tinted filter that resulted in increased visual comfort and concluded that the use of precision tinted lenses would be a reasonable first step to increase comfort and should be considered as an adjunctive treatment in patients with ABI and photosensitivity.
In the 2017 University of Cincinnati Department of Neurology and Rehabilitation Medicine study , the team addressed the use of dark sunglasses as a problematic solution to light sensitivity. Dark sunglasses, while they reduce the amount of incoming light, are not practical indoors or in low light situations and add to eye strain as the information is dimmed and more difficult to process. Patients in this study were provided with a wide range of stock filter colours to choose from. The study found that sensitivity to certain wavelengths of light can be reduced with a strategy that includes colour-tinted glasses and that the use of these glasses may aid in the recovery process.
In 2018, the Journal of Neurotrauma published findings that using nonliquid crystal display (non-LCD) computer screens are effective in treating photosensitivity and computer screen intolerance. 
Since 2015 Opticalm has provided individually prescribed coloured filter lenses and other assistive tools such as tuneable colour light bulbs, screen tinting software, and more recently non-LCD computer monitors to help several hundred clients manage their unpleasant physical and visual perceptual symptoms. The majority of these clients, referred to us by their health practitioners, have been suffering from post-concussion vision issues. Clients are carefully screened to ensure that other vision needs are addressed prior to the assessment and symptoms indicate the presence of visual stress so that tinted filters will likely be effective. Individually prescribed coloured filter lenses were selected by over 95% of the individuals tested, showing an average 30% rate of reading improvement and a great number of subjective improvements like reduction in headaches and anxiety, increased visual comfort, improved balance, and improved cognitive functioning and alertness.
Considering the overlap of symptoms and the findings of these published papers, it would make sense to investigate for and treat visual stress if sensitivities to light and pattern are reported by individuals with post-concussion or post-ABI syndrome.
 Jackowski M.M., Sturr J.F., Taub H.A., Turk M.A. Photophobia in patients with traumatic brain injury: uses of light-filtering lenses to enhance contrast sensitivity and reading rate. NeuroRehabilitation. 1996; 6:193–201.
 Fimreite v, Willeford K, Ciuffreda KJ. Effect of chromatic filters on visual performance in individuals with mild traumatic brain injury (mTBI): A pilot study. Journal of Optometry 2016 Oct-Dec; 9(4): 231–239
 Mansur A, Hauer TM, Hussain MW et al. A nonliquid crystal display screen computer for treatment of photosensitivity and computer screen intolerance in post-concussion syndrome. Journal of Neurotrauma Aug 2018 35:1886-1894