Usually a difference in discrimination, not absence of color
Color vision deficiency can make certain colors or shades difficult to distinguish. Red–green differences are common; blue–yellow and complete color deficiencies are different categories. Many inherited forms are longstanding, but acquired changes also occur. [1]
Eye disease, some medicines and other factors can cause acquired changes. A new or asymmetric color difference deserves an assessment rather than being assumed to be the same as a lifelong inherited pattern. [2]
Several types
Red–green, blue–yellow and complete deficiencies are different.
More than hue
Brightness and contrast also affect real-world tasks.
Design for access
Labels and shapes can carry information alongside color.
Terms in this guide
- Color discrimination
- The ability to distinguish colors or shades.
- Acquired
- Developing later, rather than necessarily being an inherited lifelong pattern.
One condition. Different experiences.
These original illustrations use different color-transform approximations. They do not show exactly what another person perceives and are not diagnostic plates.
Original VisualSim schematic illustrations, informed by the cited clinical descriptions. These are not study figures, patient recordings or validated severity levels. Clinical basis: source 1. Artwork: © VisualSim; see image provenance.
Color processing and what a screen can approximate
Cone photoreceptors and subsequent visual processing support color discrimination. Inherited differences and acquired disease do not all act in the same way. The clinical history and appropriate testing help distinguish them. [2]
A simulation transforms RGB pixels for someone viewing a display. It cannot create the subjective experience of another visual system or compensate for every display gamut, brightness setting and viewing condition. Use it to examine possible color confusions rather than claim an exact shared perception.
What can look similar?
Inherited versus acquired
A lifelong pattern differs clinically from a recent change. Timing and differences between eyes matter. [2]
Reduced color from cataract
Lens changes can alter color appearance without being an inherited red–green deficiency. [2]
Contrast or labeling problems
A task can be inaccessible because it relies on color alone, even when a simulation seems easy to interpret.
Similar-looking symptoms can have different causes. A matching picture cannot establish a diagnosis.
What an assessment may involve
Clinical color tests are used in controlled conditions and interpreted with the history and other eye findings. Online plates and simulated images can be affected by the screen and viewing conditions; they are not a substitute for formal assessment. [3]
- Describe the historyLifelong or new? One eye or both? Which tasks are affected?
- Use an appropriate testAsk which test answers the clinical or functional question.
- Discuss practical adjustmentsConsider labels, contrast, patterns and alternatives to color-only cues.
What may help—and what is still being studied
Management depends on whether the difference is inherited or acquired and on the cause. Tinted filters may change appearance for some users, but they should not be described as restoring normal color vision. [1]
A 2018 study of EnChroma glasses found changes in appearance without improved results on the tested diagnostic tasks. That result concerns the filters and methods studied; it does not mean every subjective preference or every aid has the same effect. [4]
Small experiments can detect an appearance change without showing restored color discrimination. A 2024 study of ten deuteranomalous observers found changes in matching and selected appearance measures, with minimal threshold-discrimination benefit. This does not establish normal color vision, occupational fitness or broad everyday benefit. [5]
What this can mean for daily life
Communicate without color alone
Pair colored information with words, icons, position or patterns. Ask for medication and equipment labels that can be distinguished reliably.
Evaluate the real task
Use actual task requirements and qualified assessment for safety or occupational decisions. A transformed photograph cannot establish eligibility.
Bring a clearer description to your appointment
Choose the questions you want to discuss. These choices stay in this page’s memory.
Research, with the context left in
Changes in perceived color, performance on a discrimination task and a person’s preference are different outcomes. Research should identify which one it measured.
What the evidence supports
Research needs to separate changes in color appearance from improved discrimination and from normal color vision. Accessibility changes can be useful regardless of whether a filter is preferred. Acquired changes and rare cone disorders require different clinical pathways from common inherited red–green differences.
How we select and interpret researchNational Eye Institute: Testing for color vision deficiency
Explains color plates, anomaloscope and hue tests. Appropriate testing and clinical context matter more than matching one transformed photograph.
Limits and applicability: Screen settings affect online examples. A simulator cannot diagnose the type, establish occupational eligibility or replace controlled assessment.
How to read this evidence: An authoritative introduction to test types; not an intervention trial or a complete occupational standard.
Gómez-Robledo et al.: Do EnChroma glasses improve color vision?
The tested filters changed appearance without restoring normal color vision or improving the tested diagnostic performance.
Limits and applicability: Do not turn these specific tests into a claim that every wearer, appearance judgment or possible aid has no benefit.
How to read this evidence: Controlled task evidence can test specific marketing claims, with limited generalization to other outcomes.
Álvaro et al.: Coloured filters and congenital color vision deficiency
EnChroma did not significantly improve CVD performance on the tested discrimination, naming and sorting tasks. Simulation filters impaired normal observers in selected tasks.
Limits and applicability: Results apply to these filters and methods, not every real-world task, long-term adaptation period or individual preference.
How to read this evidence: Multiple tasks provide a useful check on specific filter effects; sample sizes remain small.
Somers, Franklin and Bosten: Empirical tests of EnChroma filters in deuteranomaly
Found changes in color matching and selected red–green appearance measures, with minimal threshold-discrimination benefit. This helps explain why subjective changes can coexist with negative diagnostic-test findings.
Limits and applicability: One CVD subtype, selected stimuli, ten observers and short follow-up. It does not establish normal color vision, occupational fitness or broad everyday benefit.
How to read this evidence: Small direct experimental evidence supports a narrow appearance effect, not a general clinical cure.
Questions researchers still need to answer
- Which aids improve a defined real-world task, rather than only changing appearance or improving a selected test?
- How do effects vary by CVD subtype, lighting, display and duration of adaptation?
- Which school, healthcare, transport and digital-design adjustments improve access without requiring someone to identify their CVD publicly?
These are editorial interpretations, not formal GRADE ratings or independent clinical review. A large sample, recent date or well-known publisher does not make every claim certain.
Trusted places to go next
Selected clinical references, research and support organizations. Each link explains who it is for.
NEI: color vision deficiency
Types, causes, testing and practical information.
NEI: testing
Understand the role of formal color tests.
Filter evaluation study
The methods and measured outcomes behind a filter claim.
Organizations & ways to connect
Selected charities, professional organizations and communities, with their scope and region. Official pages checked 24 October 2026. Community discussions are peer support; each external service has its own privacy and moderation rules.
National Eye Institute
Patient information and publicly funded vision-research education. This is an educational resource, not a personal diagnosis or a patient support group.
Connections listed by the organization.
Color Universal Design Organization (CUDO)
Promotes communication and product design that work across color-vision differences. Focuses on usable information, including shapes, text and patterns alongside color.
Connections listed by the organization.
BCM Families Foundation
Research and family information specifically for blue cone monochromacy, not all red–green CVD. Its registry is an external, voluntary research service with separate consent and privacy terms.
Connections listed by the organization.
The Achromatopsia Group
Links to achromatopsia discussion and support networks. Achromatopsia differs from common red–green CVD. Peer experiences are not medical advice; membership may be required.
Connections listed by the organization.
Colour Blind Awareness: archived information
The official About page says the organization has been inactive since 1 January 2025, may have outdated information and cannot answer enquiries. Use archived education material cautiously; do not expect current support.
Questions you may still have
Does color vision deficiency always mean seeing in gray?
No. Complete color deficiency is different from the more common difficulties distinguishing particular colors. [1]
Can this page diagnose the type?
No. A screen simulation is not a clinical color test.
Do these sliders show exactly what another person sees?
No. They approximate selected color transformations for the current observer and display.
Sources, image credits and review status
Compiled by VisualSim from clinical references and published research. Sources checked 24 October 2026. Independent clinical review has not been recorded; no named clinical reviewer or clinical validation is claimed. Research evidence and its limitations are linked below.
- National Eye Institute. Color blindness. Clinical information; sources checked 24 October 2026.
- National Eye Institute. Causes of color vision deficiency. Clinical information; sources checked 24 October 2026.
- National Eye Institute. Testing for color vision deficiency. Clinical information; sources checked 24 October 2026.
- Gómez-Robledo et al. Do EnChroma glasses improve color vision for colorblind subjects? (2018). Clinical information; sources checked 24 October 2026.
- Somers, Franklin and Bosten. Empirical tests of the effectiveness of EnChroma filters in deuteranomaly (2024). Clinical information; sources checked 24 October 2026.
- Álvaro et al.: Coloured filters and congenital color vision deficiency (2022). Controlled psychophysical experiments; 16 CVD and 20 color-normal participants, with additional replication samples
The simulator helps people communicate an experience. It cannot diagnose a condition, measure a visual field, or establish that someone is safe to drive.