Signs, symptoms, and diagnostic criteria
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.
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.
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
the sensation of heat at the back of the head;
eye pain and strain;
nausea from movement; and
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
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:
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.
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)
1.2. Neurological disease and injury
Acquired brain injury (ABI)
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
Disorders of accommodation
Photophobia - visual discomfort
Post-trauma vision syndrome
Visual distortions and disturbances
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
Persistent postural-perceptual dizziness PPPD
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.
Headaches and head pain
Pain from lights
Hypersensitivity to sound
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
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.
Occasional double vision
Reduced field of vision
Difficulty settling on vision prescription
Difficulty tolerating stock lens filters
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.
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.
2.4. Psychological difficulties
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
Artificial lighting (other)
Late afternoon daylight
Computer screens or electronic devices
LED vehicle head or taillights
3.2. Glare sensitivities
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
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
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