A hex color code like #A3B18A sits inside a much larger design conversation once you start asking not just "what color is this" but "how does someone with a color vision difference actually perceive this," and the honest answer is more nuanced than most casual design advice suggests, because color vision deficiency itself isn't one single uniform condition.
Color blindness isn't one condition, it's a family of related ones
The umbrella term "color blindness" actually covers several genuinely distinct conditions, each affecting color perception differently, based on which of the eye's three types of color-sensing cone cells is affected. Red-green color vision deficiency (which itself splits further into protanopia and deuteranopia, affecting slightly different but overlapping parts of the red-green spectrum) is by far the most common category, affecting a meaningful share of men in particular due to the specific genetics involved. Blue-yellow deficiency (tritanopia) is considerably rarer. Complete color blindness, where someone perceives no color distinction at all, is rarer still. Treating "color blindness" as one uniform condition with one uniform visual experience misses this real underlying variation.
Why red-green combinations specifically cause the most common problems
Because red-green deficiency is the most common category by a wide margin, the classic accessibility failure case in design is a red-versus-green color coding scheme — a common pattern for "error" versus "success" status indicators, for instance — since that's exactly the color distinction most affected by the most common form of color vision deficiency. Someone with red-green deficiency may perceive both colors as landing in a similar, hard-to-distinguish part of their visual spectrum, meaning a status indicator relying purely on "is it red or is it green" to convey meaning can be genuinely difficult or impossible to interpret correctly through color alone.
Why relying on color alone is the actual root problem, not any specific color pairing
The deeper, more general accessibility principle — closely related to the WCAG contrast ratio discussion covered in an earlier post on this blog — is that information shouldn't be conveyed through color alone in the first place, regardless of which specific colors are chosen. A red-versus-green status indicator is a commonly cited example specifically because it maps onto the most common form of color vision deficiency, but the same underlying accessibility failure exists for any color pairing used as the sole information carrier, if that specific pairing happens to fall within a range some viewer's color vision doesn't distinguish well. The fix isn't finding a "safer" pair of colors — it's adding a second, non-color-dependent cue (an icon, a text label, a pattern, a position) that conveys the same information redundantly, so a viewer who can't reliably distinguish the color difference still has a complete, independent way to understand the meaning.
Why simulating color blindness in software is inherently an approximation
Software tools that simulate how an image or design would appear to someone with a specific type of color vision deficiency are genuinely useful for design review, but they're built on generalized mathematical transformation models representing a typical case of a given deficiency type, not a precise simulation of any one specific individual's actual vision — real color perception varies somewhat even among people with nominally the same diagnosed category of color vision deficiency, similar to how visual acuity varies among people who all technically fall into the same eyeglasses prescription range. A simulation tool is a valuable design-review aid for catching an obviously problematic color-only distinction, but it shouldn't be treated as a perfectly precise stand-in for how every individual with that condition actually experiences a specific design.
Practical design habits that address this systematically
Rather than trying to individually vet every color pairing in a design against every possible type of color vision deficiency, a more systematic and reliable approach is building the habit of never relying on color as the sole information carrier anywhere in a design — pairing every meaningful color distinction with a redundant non-color cue as a default practice, rather than as a special exception applied only after a specific accessibility complaint surfaces. This single habit addresses the underlying problem more comprehensively than trying to individually reason about which specific color pairs are or aren't safe for every possible variant of color vision deficiency.
Checking a design for this specific issue
Our color blindness simulator lets you upload an image and preview it under several common types of color vision deficiency, which is a useful design-review step for catching an obviously color-only distinction before it ships — while keeping in mind, per everything above, that it's a helpful approximation for design review rather than a precise stand-in for any one individual's specific visual experience.