Who has the worst eyesight in the world

So, who's got the worst eyesight on the planet? It's not one unlucky person. It's whole groups of people, and some weird animals. In humans, the absolute worst uncorrected vision belongs to folks with severe myopia — like, beyond -20 diopters — or those who are legally or totally blind from things like retinal detachment or glaucoma. But then you look at animals, and some have evolved to have vision that's just... terrible. A few are basically blind.

Which human populations have the highest rates of poor eyesight?

The World Health Organization and other eye health folks say the worst vision problems are in low- and middle-income countries. Think sub-Saharan Africa and South Asia. The big culprits? Uncorrected stuff like nearsightedness, farsightedness, astigmatism, plus cataracts, glaucoma, and diabetic retinopathy.

A 2023 report from the International Agency for the Prevention of Blindness says nearly 80% of the world's 43 million blind people live in developing nations. Rural areas in India, China, and parts of Africa are hit hardest. In some parts of Ethiopia and Nigeria, blindness rates top 1% of the population. That's double the global average of 0.5%.

Now, for severe myopia — worse than -6.00 diopters — East Asian countries like South Korea, Japan, and China have the highest rates among young adults. In some cities, over 20% of them have it. Blame it on tons of near-work and not enough outdoor time as kids.

What animal has the worst eyesight in the world?

Some animals are famous for having crap eyesight. They rely on smell, touch, or echolocation instead. Here are the champs of bad vision:

• Blind cavefishAstyanax mexicanus): These guys live in pitch-black caves. Evolution just ditched their eyes entirely. They're totally blind.
• Star-nosed mole (Condylura cristata): This mole's eyes are tiny and underdeveloped. It can only tell light from dark. Useless for finding its way around.
• New Zealand native weta (Deinacrida heteracantha): A giant insect with compound eyes that only pick up basic light intensity. No shapes, no colors.
• Texas blind salamander (Eurycea rathbuni): Another cave-dweller. Its eyes don't work — they're covered by skin.
• Box jellyfishChironex fleckeri): It has 24 eyes, but its vision is insanely blurry. Just detects light and dark. No image-forming ability.

If I had to pick the worst, it's either the blind cavefish — it's lost its whole visual system — or the star-nosed mole, whose eyes are so small and degenerate they're basically decoration.

What is the highest prescription for eyeglasses ever recorded?

The highest recorded eyeglass prescription for nearsightedness? About -108 diopters. That's from a 2016 study in Optometry and Vision Science. This patient had extreme myopia from something called pathological myopia — the eyeball is way too long. For farsightedness, the highest is around +50 diopters. These are rare, and you need custom lenses or surgery to deal with them.

For comparison, a typical strong prescription is -10 to -15 diopters. -20 is legally blind without correction. -108 means you'd have to hold stuff less than 1 centimeter from your eye to see it clearly. Wild.

Can poor eyesight be inherited or is it caused by environment?

It's both. Severe myopia — the worst human eyesight — often runs in families. Over 200 genes are linked to refractive. But environment matters too. Too much near-work (reading, screens), not enough outdoor time as a kid, bad lighting — all can speed up myopia. Conditions like retinitis pigmentosa and glaucoma are mostly genetic. Cataracts? More about age, UV exposure, and diet.

The mix is complicated. Someone with a genetic tendency for myopia might not get severe vision loss if they play outside a lot as kids. Same genes, but heavy screen time? They might end up with a high prescription. It's messy.

What medical conditions cause the worst eyesight?

The most severe vision loss usually comes from:

• Retinal detachment: Emergency — the retina peels off the back of the eye. If you don't treat it fast, you go blind.
• End-stage glaucoma: The optic nerve gets damaged permanently. Often leads to total blindness.
• Macular degeneration: Top cause of legal blindness in older adults. Destroys your central vision.
• Diabetic retinopathy: Uncontrolled diabetes causes bleeding and scarring in the retina. Severe vision loss follows.
• Retinoblastoma: A rare eye cancer in kids. Can cause complete vision loss in the affected eye.

These conditions can give you visual acuity of 20/200 or worse — legal blindness — or even no light perception at all. That's total blindness.

Data Table: Worst Eyesight by Category

FAQ: Who has the worst eyesight in the world?