Vision

What Is Visual Processing?

Visual processing is how the brain understands what the eyes see. It includes: 

• How the eyes work together (binocular vision) 

• Eye tracking while reading 

• Fast eye movements 

• Visual comfort 

• Perception of shapes, patterns, and colours 

If someone has trouble with visual processing, they may be referred to an orthoptist—a specialist in eye movements and binocular vision. 

Some people with Autistic Spectrum Disorders (ASD) or other developmental conditions may be hypersensitive to colour, light, glare, patterns, or contrast. In severe cases, they may experience a visual whiteout, where they temporarily lose the ability to see. 

Signs of Visual Processing Difficulties

Under-Responsive

• Has trouble finding items in busy backgrounds 

• Struggles to locate friends in crowded areas 

• Finds it hard to follow text on a page 

Over-Responsive

• Dislikes bright lights 

• Prefers dim or dark rooms 

• Covers or shades their eyes 

• Blinks a lot or has watery eyes when lighting changes 

• Wears a peaked cap, keeps a hood up indoors, or lets hair cover their face 

Seeker

• Looks at shiny or reflective objects 

• Flicks fingers near their eyes 

• Enjoys flashing lights and bright colours

What to Do

If your child is over 7 and shows several of these signs, consider an orthoptic assessment. Orthoptists are trained to assess eye movements and how the eyes work together. 

What Orthoptists Do

Orthoptists are specialists who help with visual processing difficulties. They: 

• Identify visual problems that affect reading and writing 

• Support children and young people (CYP) in a person-centred way 

• Offer advice to parents, teachers, and education staff 

• Provide guidance to schools, colleges, and universities 

📄 More information from the British and Irish Orthoptic Society 

To access support, ask your general practitioner (GP) or optometrist to refer you to the Royal Cornwall Hospital Trust (RCHT).Description text goes here

NHS Orthoptic Visual Processing Difficulties (VPD) Clinic

The Visual Processing Difficulties (VPD) Clinic helps CYP with eye problems that affect reading or learning. It is run by orthoptists. Speak to your GP or optometrist for a referral to Royal Cornwall Hospital Trust (RCHT). 

Visual Sensitivity

Some CYP are very sensitive to visual input. For example, they may: 

• Say lights are too bright 

• Want to wear sunglasses indoors 

Start by getting an eye test to rule out eye health issues or the need for glasses. 

1. Light Sensitivity

Bright lights, sunlight, glare, and flickering lights can overwhelm the nervous system. This may cause: 

• Fatigue 

• Anxiety 

• Dizziness 

• Headaches 

Fluorescent lights can reflect off surfaces and feel blinding. 

2. Contrast Sensitivity

Some CYP struggle to read black text on a white background. The contrast makes letters hard to see clearly. 

3. Impaired Print Resolution

Letters may appear to shimmer, move, or break apart. 

4. Environmental Distortion

In busy places, objects may lose meaning. A CYP might only see shapes and colours moving around. This can cause them to: 

• Avoid eye contact 

• Resist climbing stairs 

• Prefer staying still 

Vision and Motor Skills

Vision and movement are closely linked. CYP use their eyes to guide their hands and feet. For example: 

• When learning to type, they look at their fingers 

• As they learn the pattern, they rely more on body awareness (proprioception) and balance (vestibular system) 

• Eventually, they can look at the screen while typing 

Ways to Help with Visual Sensitivity

1. Modify Lighting

Use softer lighting for comfort. Try: 

• Dimmer switches 

• Coloured bulbs 

• Multi-head lamps that can be adjusted 

2. Reduce Glare

If sunlight is a problem: 

• Provide sunglasses 

• Move desks away from windows 

• Use portable window shades 

3. Increase Visual Input

For CYP who need more stimulation: 

• Use colour-coded systems to organise items 

• Add bright lighting to workspaces 

• Try a projection night-light or lamp for bedtime 

4. Reduce Visual Clutter

Too many colours or decorations can overwhelm some CYP. Help by: 

• Keeping rooms tidy 

• Limiting posters and knickknacks 

5. Ease Eye Contact Pressure

Some CYP find eye contact distracting. Instead of saying “look at me,” try: 

• Asking them to listen and respond 

• Suggesting they look in your direction if needed 

6. Improve Safety

Some CYP struggle to judge where their body is in space. They may bump into things or trip. You can help by: 

• Using simple, contrasting colours in home décor 

• Avoiding busy patterns on rugs or wallpaper 

• Using coloured tape to mark doorframes and edges 

📄 Source: Understood.org – Helping Children with Visual Sensitivity 

Visual Stress

Visual Stress describes symptoms of visual fatigue during reading. Some people find that using colour helps reduce these symptoms. Other names for this condition include: 

• Meares-Irlen Syndrome

• Irlen Syndrome

• Scotopic Sensitivity Syndrome (SSS)

This condition is not yet widely recognised by medical and scientific communities, and there is no agreed name for it. 

How Coloured Overlays Help

Coloured overlays can reduce visual distortions in text. They help some children and young people (CYP) read more easily and with less discomfort. Each person may need a different colour, so it’s important to test a wide range. 

In studies with primary school children, about 1 in 5 found that a coloured overlay made reading clearer. These CYP used their chosen overlay for more than three months and read faster with it. 

Symptoms of Visual Stress

CYP may report: 

• Glare from the page 

• Headaches while reading 

• Sore eyes 

• Blurred or moving text 

Signs of Visual Stress

You might notice: 

• Rubbing eyes 

• Blinking often 

• Poor concentration 

• Slow or inefficient reading 

• Losing place on the page 

Who Benefits?

CYP who benefit may: 

• Be good readers who tire quickly 

• Struggle with reading and feel discomfort 

• Say that letters move or blur 

• Have a family history of migraines

Is It Linked to Dyslexia?

CYP with reading difficulties are more likely to report visual distortions and benefit from overlays. Some good readers also benefit. 

People with dyslexia may have visual perception issues, but they also have language-based difficulties that need separate support. 

Do CYP Need Overlays or Glasses Long-Term?

CYP often benefit most when overlays are introduced early—before reading becomes frustrating. Many use overlays for a year or two and then stop, as they become more familiar with reading and less distracted by distortions. 

Can Overlays Be Used with Eye Exercises?

Yes. CYP can use overlays while doing orthoptic eye exercises or receiving medical treatment. If binocular vision problems cause the distortions, it’s best to correct those first. If problems continue, coloured filters may help.