Related condition


Visual snow refers to the persistent visual experience of flickering fine achromatic dots in the whole visual field of both eyes likened to ‘‘static analogue television noise”. Symptoms are strongly associated with palinopsia, the persistence of previously viewed stimuli, and migraine, and the condition is often misdiagnosed. [1] 


Visual stress is a visual sensory processing disorder that is characterized by symptoms of visual perceptual distortions and eyestrain when viewing patterned images, such as text, and individually prescribed coloured filters alleviate symptoms. [2] Common symptoms include blurring, doubling, and the appearance of movement, flickering and colour in the visual field. Visual stress is often associated with migraines and is also frequently misdiagnosed.   


Research into visual snow by a team of ophthalmologists in Australia reported that colour filters, identified using an Intuitive Colorimetry device, subjectively reduced symptoms of visual snow. The paper also refers to evidence that visual snow can be linked to other disorders of visual and sensory processing such as migraines.  They concluded that “the colour filters may alter the visual processing that helps regulate the electroencephalographic (EEG) overactivity and lead to the reduction of symptoms.” [1] 


Research into visual stress has demonstrated with QEEG, fMRI and other brain scans, that it is associated with migraines, and that individually selected colour filters, using the Intuitive Colorimeter device, reduce the hyperBOLD response in migraine. [3] 


The Australian paper also notes that visual snow frequently occurs with palinopsia, the persistence of previously viewed stimuli. [1] During our visual stress assessment, when asked to view a patterned target image and then look away, the perceptual distortions caused by the patterned image often transfer to the next image. This effect is removed when clients wear their precision tinted combination trial lenses identified with the Intuitive Colorimeter Device.    


The overlapping symptomology between individuals with visual snow, migraine and visual stress, and their similar increased sensitivity to sensory perception would seem to indicate that it is important to rule out and treat visual stress if it is a contributor to symptoms.   

 In the examples listed below, clients were diagnosed with visual snow by their neurologist or ophthalmologist. They were referred to us for a visual stress assessment to determine if precision tinted lenses would relieve some of their perceptual distortions and associated discomfort. The assessments yielded different results for these clients: 


  • Client 1:  When wearing their precision tinted lenses, this client reported the elimination of all perceptual distortions, including their visual snow.  While we are not in a position to discount the diagnosis of the visual snow, because the clients reported distortions were very like those that indicate visual snow, it may be that visual stress was the cause of the visual distortions.


  • Client 2:  When this client wore their precision tinted lenses, the reduction of perceptual distortions led to increased comfort, reduced head pain, and a reduction in the visual snow. While the visual snow was still visible against some flat surfaces, it was less apparent and easier to tolerate, so the precision tinted lenses were purchased. 


  • Client 3:  Wearing precision tinted lenses helped remove the perceptual distortions (a blurring and haziness), making the visual snow more apparent and described as "sharper."  In this case, it was preferred to have the distortions as they softened the visual snow and the precision tinted lenses were not purchased. 


In conclusion, when visual snow is present,  a visual stress assessment should be performed to determine if it's contributing to symptoms and if precision tinted lenses could offer some relief. 




[1] Lauschke JL, Plant GT, Fraser CL. Visual snow: a thalamocortical dysrhythmia of the visual pathway? Journal of Clinical Neuroscience. 2016; 28:123-27 


[2]  Evans AJ, Allen PM, Wilkins AJ. A Delphi study to develop practical diagnostic guidelines for visual stress. Journal of Optometry. 2017; 10:161-68 


[3] Huang J, Zong X, Wilkins AJ, et al. FMRI evidence that precision ophthalmic tints reduce cortical hyperactivation in migraine. Cephalalgia 2011; 31:925-36