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Signs, symptoms, and diagnostic criteria


Individuals may not be aware that they are experiencing visual distortions. They may lead to loss of clarity and general visual irritation.

WARNING: The following images can cause discomfort and trigger reactions in some individuals.

Man with headache in bright room with electronics

Before reading the entire content of this page, it’s essential to understand the difference between signs, symptoms, and diagnostic criteria.

Signs are things that someone might observe in a student, client, patient, or family member. They are objective, and possible evidence that the individual being observed may have Visual Stress. Whereas symptoms are apparent to the patient himself, therefore, subjective in indicating the presence of the condition.

On the other hand, diagnostic criteria, validated through research and studies, are a set of signs, symptoms, and tests used by clinics to diagnose patients with Visual Stress and care for the individuals afterward.

The material below describes these signs, symptoms, and diagnostic criteria of Visual Stress!


When investigating signs of Visual Stress, observation is integral in diagnosing the condition. Because individuals may not realize they are doing these things believing that the discomfort or distortions they experience are normal and shared by everyone.

tracking text with finger when reading book

Common signs

  • Wearing brimmed hats or sunglasses inside. 

  • Turning off or dimming the lights inside. 

  • Keeping the blinds closed. 

  • Sitting in dark places to read, study or work.  

  • Dimming computer screens and avoiding working on them for extended periods.  

  • Having difficulty reading without using a finger. 

  • Having difficulty writing neatly and well-spaced.  

  • Skipping words or lines when reading aloud. 

  • Appearing uncomfortable when reading or doing deskwork. 

  • Squinting, rubbing eyes, angling the head to read, shaking the head or constantly changing positions.  

  • Easily distracted. 

  • Frustrated, fidgety, and restless when reading or doing homework. 

  • Having trouble with their vision prescriptions even if they are adjusted. 

  • Not tolerating UV, blue blockers, or antireflective coatings on glasses (these are filters).

Note: While these could be signs of Visual Stress, it is essential to investigate other possible causes.

In the Vision and Reading Difficulties book, Dr. Wilkins, Dr. Evans, and Dr. Allen cautioned people not to assume that it is Visual Stress because there are many factors to consider. Signs may also indicate an undiagnosed refractive error or even binocular vision problems. It could also be a combination of all two with Visual Stress; thus, both should be corrected.

No matter the apparent cause of the problem, anyone with difficulty reading should have a complete vision investigation by an eye care professional specializing in vision and learning. This assessment can occur in conjunction with a Visual Stress assessment, as Visual Stress may still be present even after vision correction. 



Many symptoms, which are apparent to the patient themselves, are related. If perceptual distortions are experienced in patterns (i.e., a high-contrast patterned carpet), things may appear distorted or moving, leading to feelings of nausea and dizziness. If flickering is perceived on smooth surfaces, concentrating in an office or classroom filled with laminated and shiny surfaces, such as desks and whiteboards, will likely be challenging.

Key symptoms of Visual Stress primarily include physical discomforts such as 

  • headache; 

  • the sensation of heat at the back of the head; 

  • eye pain and strain; 

  • visual fatigue; 

  • cognitive fatigue; 

  • nausea from movement; and 

  • discomfort. 

woman with headache

They also include visual perceptual difficulties, such as

  • perceived excessive luminosity; 

  • visual sensory overload; 

  • illusions of shape, motion, and colour; 

  • blurring and double vision; 

  • reading and tracking difficulties; 

  • depth perception difficulties; and 

  • anxiety. 

Diagnostic criteria

The Visual Stress & Colorimetry Assessment Tool (VSCAT) is a software as a service (SaaS) application used to support the comprehensive process for evaluating individuals for Visual Stress. This tool is designed for use by the general public, with some more advanced components for eye care, health care and education professionals working with individuals with neurological, neurodevelopmental, and neuropsychiatric conditions where the visual system is compromised.

In 2016, the Journal of Optometry published the “Practical Diagnostic Guidelines for Visual Stress” identifying most of the criteria now used to diagnose Visual Stress. This guideline was developed through a Delphi study that focussed primarily on reading difficulties. The following indicators were identified as diagnostic criteria for Visual Stress.

  • Sensitivity to patterns leading to an abnormally high score on the Pattern Glare Test. 

  • Perceptual distortions such as illusions and movement in text. 

  • Sensitivity to light, glare, and flicker. 

  • Voluntary use of an overlay or other filter types for a prolonged period, including avoidance of reading without the filter. 

  • Improved performance of 15% or more with the filter on the Wilkins Rate of Reading test. 

  • Family history of migraine, epilepsy, learning difficulties, and Visual Stress. 


Since then, more criteria have been added to address light sensitivity and other difficulties to the guideline based on clinical work, such as Opticalm’s Visual Stress pre-screening process. These diagnostic criteria, listed below, are used, by Opticalm and their provider network, to identify individuals who may have Visual Stress and who may benefit from custom precision tinted lenses and other assistive tools and technologies. The criteria can be grouped into three distinct areas:

  1. Diagnoses

  2. Difficulties 

  3. Sensitivities 


It is also essential for individuals with, or who think they have, Visual Stress to consider family medical history when going through the list of diagnostic criteria. While you may not be aware that you are suffering from a specific condition, hereditary conditions may eventually surface or contribute to Visual Stress symptoms. 

women taking down notes

1) Diagnoses - Neurological and visual diagnoses and disorders 

Neurological conditions and visual disorders are often associated with Visual Stress as they may lead to neuro-hyperactivation (hyperactivation of the visual cortex), likely compromising the visual system. Below is the list of these neurological conditions.

For more information on related conditions and the research into the condition and the use of precision filters, click here!

1.1. Neurodevelopmental disorders 

Attention deficit hyperactivity disorder (ADHD)  

Autism spectrum disorder (ASD) 

Sensory processing disorder 

Specific learning difficulties (includes dyslexia) 

Tourette syndrome 

1.2. Neurological disease and injury 

Acquired brain injury (ABI) 

Lyme disease 

Multiple sclerosis (MS) 

Viral Infection - Post-COVID syndrome 

Post-concussion syndrome (PCS) 


Whiplash-associated disorder with neurological 


1.3. Neuropsychiatric disorders 

Generalized anxiety disorder 

Major depressive disorder 

Post-trauma stress disorder (PTSD) 


1.4. Vision diagnoses and disorders 

Convergence insufficiency 

Disorders of accommodation 

Double vision 

Photophobia - visual discomfort 

Post-trauma vision syndrome 

Visual distortions and disturbances 

Visual hallucinations 

Vision sensitivities (contrast/glare) 

Visual snow - other visual disturbances 

Visual Stress - disorders of the visual cortex 


1.5. Neurological disorders 

Chronic fatigue/myalgic encephalomyelitis 

Chronic cluster headache syndrome 

Chronic post-trauma headache 

Migraine headaches 

Persistent postural-perceptual dizziness PPPD 

Photosensitive epilepsy 

Vestibular disorders 

2) Difficulties

Seven categories of difficulties commonly reported by individuals with Visual Stress can also be observed by parents, teachers, or healthcare providers as challenges to learning, working, or rehabilitation.

These are usually the first signs that an individual may have Visual Stress.

Functional, the things that are difficult to do; physical, the discomfort experienced when doing them; and behavioural, the things that are done to manage the first two difficulties.

Physical difficulties 

Headaches and head pain 

Eye pain 

Neck pain 

Pain from lights 


Cognitive fatigue 

Physical fatigue 

Hypersensitivity to sound 


Functional difficulties  

Shopping in bright, active environments 

Working in open concept busy environments 

Working on computers and other screens 


Tracking – loses their place when reading 

Writing - messy and poorly spaced 

Paying attention and concentrating 

Staying on task 

Being on escalators or moving vehicles


Behavioural difficulties  

Wears a hat or sunglasses inside 

Uses a finger to keep their place when reading 

Fidgets when working or reading 

Avoids crowds or public spaces 

Rubs, squints, or widely opens their eyes  

2.1. Functional, behavioural, and physical difficulties

The perceptual distortions and illusions often reported in the text are also experienced and reported in the visual environment. These are often identified when Visual Stress is present and are both key indicators of the condition. When Visual Stress is the cause, attempts to resolve symptoms with standard optometric solutions will unlikely lead to symptom reduction.

Visual difficulties 

Inconsistent blurring  

Occasional double vision 

Reduced field of vision 

Difficulty settling on vision prescription 

Difficulty tolerating stock lens filters 


Perceptual difficulties 

Stars or lights in vision 

Dots, static, snow, or pixelization of images 

Ghosting, trailing, or after-images 

Floors, walls, and/or doorways appear warped 

Objects are not perceived at the correct distance 

Objects or words that appear to be moving but are not 

2.2. Visual and perceptual difficulties

This type of difficulty is often the result of visual and perceptual difficulties. Perceptual distortions of the environment can lead to vestibular symptoms. Unless the misperception of the environment is addressed, the individual may continue to perceive the world as skewed and, thus, perceive themselves as being off balance.

Vestibular difficulties

Dizziness or feeling unsteady 

Vertigo, or the sensation of spinning  

The sensation of rocking or floating 

Imbalance and coordination difficulties 

Depth perception difficulties 

2.3. Vestibular difficulties

Visual Stress symptoms may have gone unresolved for years, and the fear of triggering the unresolved symptoms can lead to psychological difficulties in some individuals.

Psychological difficulties 





2.4. Psychological difficulties

3) Sensitivities 

The modern urban visual environment can be challenging for some to manage, leading to visual discomfort and stress. The seven categories of sensitivities, light, glare, contrast, colour, pattern, flicker, and movement of Visual Stress, are all related to visual information. Individuals with neurological conditions demonstrate a high sensitivity to the following seven elements in our modern visual environment. 

Sensitivity to light is one of the key indicators of Visual Stress. Studies have demonstrated that individuals with Visual Stress have a hypersensitivity to lights or glare and often perceive it as being brighter than it is. 

3.1. Light sensitivities 

Fluorescent light 

Artificial lighting (other) 

Morning daylight 

Midday daylight 

Late afternoon daylight  

Computer screens or electronic devices 

LED vehicle head or taillights 


3.2. Glare sensitivities 

Shiny surfaces 

Light reflection from a wet surface 

White paper (appears too bright) 

Shine on a desk, poster, or wall 


3.3. Contrast sensitivity 

Black against white 

Shadows - light against dark 

The contrast of different colours or shapes 

Light, glare, and contrast sensitivities 

Light is made of different wavelengths that the human eye sees as colours. Sensitivity to, or discomfort with, specific colours is important in understanding visual triggers and the presence of Visual Stress in an individual. 


Note that voluntary use of an overlay or other filter types, for a prolonged period, including avoidance of reading without the filter, is a strong indicator to proceed with a full Visual Stress assessment to determine the custom lens colour for tinted glasses.

3.4. Colour sensitivity 

Indicator lights/digital clocks 

Decorative coloured lights 

Certain colours cause discomfort 

Certain colours create comfort 

Used coloured paper or overlays in school 

Comments on colours they like and do not like 

Colour sensitivities 

Studies demonstrate that individuals with Visual Stress are hypersensitive to patterns, flicker, and movement, often perceiving it when others do not. Sensitivities to these often indicate Visual Stress. These three sensitivities are similar, yet different. 


The visual environment in our homes, workplaces, and other environments moves quickly and is often heavily patterned. Many everyday things, such as store shelves or office carpeting, can trigger discomfort. Flicker comes from light but also from the quick change in visual information found when scrolling on your phone while driving, or watching someone talk with their hands.  


If an individual is sensitive to these three visual elements, then it may indicate the presence of Visual Stress.

3.5. Pattern sensitivity 

Tile or patterned flooring  

Patterned wallpaper and furniture 

Patterned fabrics and clothing 

Horizontal and vertical blinds 

Lined or graph paper/spreadsheets 

Store shelves lines with items 

3.6. Flicker sensitivity 

Lights dying out 

Strobe lighting 

Vehicle signal lights 

Road hazard lights/pedestrian lights 

Emergency vehicle lights 


3.7. Movement sensitivity 

Turning fan blades 

Finger or hand movements 

Television action scenes  

Falling rain or snow 

Scrolling on a computer or phone screen 

The scenery when driving or on a bicycle 

Pattern, flicker, and movement

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