Contrast Card Generator

High contrast beyond babies: CVI and low vision

High-contrast, complexity-controlled images are not only a newborn thing — they are a standard part of the toolkit for children and adults with CVI or low vision, and this generator's dials were built so that toolkit can be set to an individual, by the people who know them.

Practitioner guidanceUpdated Sep 1, 2026For caregivers, therapists, parents

Common professional practice; sensible but less formally evidenced.

In one line

High-contrast, complexity-controlled images are not only a newborn thing — they are a standard part of the toolkit for children and adults with CVI or low vision, and this generator’s dials were built so that toolkit can be set to an individual, by the people who know them.

Key points

  • CVI is brain-based, not eye-based. Cortical (or cerebral) visual impairment means the eyes may be structurally healthy while the brain’s visual processing is affected. It is among the most common causes of visual impairment in children in developed countries, and it looks different from eye-based low vision: the difficulty is often with complexity, clutter and novelty rather than sharpness alone.
  • “Low vision” is its own, broader category — reduced vision (from many causes, at any age) that glasses or treatment cannot fully correct. For both groups, stronger light-dark contrast makes material easier to find and use; that part generalises far beyond infancy.
  • What practitioners consistently describe for CVI: many children respond better to simpler displays with less visual clutter, to a single strong colour (red and yellow are commonly cited favourites), to familiar material, and with more time than you’d expect before a response (latency). Needs typically ease as the child’s visual skills develop. This is careful practitioner guidance built from assessment frameworks — valuable, individual, and not a set of trial-proven prescriptions.
  • The match to this generator is deliberate: a direct acuity input (no age required — enter what the person can resolve, at any age), a complexity dial that goes genuinely sparse, a single-target layout, a preferred-colour mode with luminance contrast kept strong, and exact feature sizing for the real viewing distance. Those are exactly the dials the CVI and low-vision guidance keeps reaching for.
  • The child’s team leads. Always. A card is material, not therapy. What to show, at what complexity, in what colour, for how long — for a child with CVI those answers come from their TVI (teacher of students with visual impairments), therapists and doctors, who assess the individual child. This tool just makes the material they ask for, at the right physical size.

Using the generator for a CVI or low-vision viewer

  • Start from the direct path: enter the measured or estimated acuity instead of an age. The sizing engine treats it exactly like an infant acuity — features land comfortably above the threshold at your stated distance.
  • Turn complexity down further than looks interesting to you. Clutter is the enemy before fineness is; one bold thing on a calm ground beats a busy sheet.
  • If the child has a preferred colour, use it as the featured colour and keep the background plain — the tool keeps the light-dark contrast strong underneath the hue.
  • Expect to wait. Latency is characteristic in CVI; a response that comes ten seconds late is still a response.
  • Reassess with the team as skills grow — the right complexity setting is a moving target here exactly as it is for infants (The Goldilocks principle: matching pattern difficulty to the stage).

The evidence

  • [established science] CVI is a leading cause of paediatric visual impairment in developed countries, and low vision affects people of every age — see the AAPOS and NEI overviews in the sources.
  • [practitioner guidance] The characteristic CVI responses — complexity and clutter sensitivity, colour preference (often red/yellow), latency, the value of familiarity, and improvement over time — come from widely used assessment frameworks (Roman-Lantzy’s CVI Range and the Perkins CVI resources). They describe patterns practitioners assess for, not universal rules, and individual profiles differ widely.
  • [our design opinion] Mapping those needs onto a direct-acuity path plus complexity, single-target and preferred-colour dials — rather than a separate “CVI mode” with someone else’s defaults baked in — is our design choice: the same physics, set to the individual by the people who know them.

Practical takeaways

  • High contrast is a whole-family accessibility feature: the same generator serves a newborn, a five-year-old with CVI, and a grandparent with low vision — with different numbers in the same three questions (who is looking, from how far, printed how).
  • For CVI: simpler, calmer, more familiar, more time. Let the child’s team pick the targets; use the tool to produce them at honest physical scale.
  • For low vision at any age: bolder and bigger at the real viewing distance beats squinting at standard print — and a poster-size print from a copy shop is cheap (print shop posters).

Caveats & disclaimer

Non-medical, and more so than usual: CVI and low vision are clinical territory, and this article deliberately stops at “what practitioners describe” and “which dials exist”. Nothing here diagnoses, treats, or substitutes for a TVI, orientation and mobility specialist, ophthalmologist or therapist — for these viewers the professional team’s guidance overrides every default this site ships. Evidence for specific visual materials in CVI is practitioner-built rather than trial-proven; we label it that way on purpose.