How a photo becomes another way of seeing.

The through-line

Vision differs from one creature or person to the next along a handful of dimensions, and every filter works by adjusting some combination of them: remapping color (for eyes with different color sensitivity), changing sharpness (for different visual acuity), adjusting light and contrast (for different light sensitivity), and adding, dimming, or distorting parts of the field of view (for conditions that affect specific regions of sight). Which of these apply, and how strongly, is what makes a dog look like a dog and cataracts look like cataracts.

So when you apply the dog filter, the app is mostly remapping color (a dog has two color receptors to your three) and softening fine detail. The cataracts filter is mostly adding haze, warming the color, and blooming bright lights into glare. Nothing is painted on from a stock image — each effect is computed from your actual photo, pixel by pixel, which is why any picture you bring in works.

The four stages of seeing

Seeing isn’t one step — it’s a chain, and a difference can enter at any link. Each filter in the app is labeled with the stage where its effect begins, which is a quick way of saying where in the process this way of seeing diverges from yours:

• Optical (front of the eye) — where light enters and is focused, before it is ever sensed. A clouding lens sits here: the image arriving at the retina is already degraded. (Example: cataracts.)
• Photoreceptor — the cells that first capture light and color. Change which receptors are present, or how they respond, and the raw color signal changes. (Examples: the color-vision filters; a songbird’s fourth receptor.)
• Retinal — the retina’s own processing, behind the photoreceptors, where the signal is assembled before it leaves the eye. Damage here removes or distorts parts of the field. (Examples: macular degeneration, glaucoma, retinitis pigmentosa.)
• Perceptual — how the brain interprets what the eye sends. The eyes can be perfectly healthy and the experience still change. (Examples: hemianopia, migraine aura, visual snow.)

It’s a simplification — real conditions often touch more than one stage, and the brain is busy compensating throughout. But it’s a useful way to see that “a vision difference” can mean very different things depending on where it starts.

Grounded in published science

We don’t invent how these look. Each way of seeing is built from measured, published vision science — cone sensitivities, acuity measurements, clinical descriptions of how a condition affects sight — and every filter’s page on this site lists the sources it draws on, so you can check our work. The color-vision filters, for instance, use a peer-reviewed model of color-vision deficiency; the animal filters draw on the spectral and acuity measurements made for each species.

Where the science is uncertain, or where the popular story turns out to be wrong, we say so rather than smoothing it over. Eagles aren’t eight times sharper than us; owls can’t see in total darkness; glaucoma isn’t a neat black tunnel; “color-blind” almost never means seeing in grayscale. We’d rather show the honest version than the dramatic one — there’s a whole page of these misconceptions if you’re curious.

What it is

Through My Eyes is a tool for curiosity and empathy. It’s a way to glimpse how a pet, a bird, or a friend or relative with a vision condition might experience a scene you both can see — to make a different way of seeing feel a little less abstract. That’s the whole purpose, and we’ve tried to build it with enough care and sourcing to be genuinely worth trusting.

What it isn’t

These are approximations for understanding, not exact reproductions. Real vision involves the brain as much as the eye, varies enormously between individuals, and can never be fully captured by reshaping a photo on a screen — a screen can’t show ultraviolet a bird sees, and it can’t reproduce one particular person’s exact experience of a condition. So the app is a way to build intuition and empathy, not a medical or diagnostic tool, and nothing in it should be used to assess anyone’s actual vision. If you have a concern about your sight, an eye-care professional is the right place to turn.