You've noticed it. Road signs come up later at night now. The small print on a pill bottle swims. You hold the menu farther out to read it. And your eyes feel the years most after dark.

So you buy help. A bottle of "eye health" gummies, maybe. Or lutein capsules and a fish-oil pill for dry eyes. It all adds up to $30 or $40 a month. And you can't really tell if any of it works.

Here's the thing. The best food for your eyes costs about a dollar. It's likely in your fridge right now. And when you cut it in half, it looks like the very thing it feeds. A carrot.

Let me tell you how a lie made that carrot famous...

It was November 1940. A Royal Air Force pilot named John Cunningham shot down a German bomber in the pitch dark. People called him "Cats' Eyes." Nineteen of his kills came at night. And the whole country wanted to know his secret...

The truth was a machine. British planes carried a new kind of radar that found bombers before any eye could. But the Air Force could not say that out loud. So it fed the papers a different tale. Their pilots ate piles of carrots, the story went, and the carrots gave them sharp eyes in the dark.

The tale spread fast. Kids grew carrots to help the war effort. Cooks traded carrot recipes. And the idea stuck for good: carrots let you see at night.

Here's the twist. That lie worked because it sat on top of a real truth. Carrots do feed your eyes — just not the way the wartime story claimed...

Take a carrot and cut it across the middle. You'll see fine rings around a bright core. It looks a lot like an iris around a pupil.

Old cooks made a simple bet. A food shaped like a body part must feed that part. The carrot looked like an eye, so people called it eye food. Charming — and this time, close to right.

So what makes a carrot orange? A pigment called beta-carotene. Your body turns it into vitamin A. And vitamin A is where the real eye work hides.

The vitamin travels to the back of your eye. There it helps build rhodopsin — the light-catcher your eye leans on in dim rooms. Dim light hits that pigment, and it sends a message to your brain. Run low on vitamin A, and you build less of it. Then dark roads and low-lit rooms turn into a blur.

Blur like that has an old name. Doctors call it night blindness. It's real, it's ancient, and too little vitamin A is the classic cause.

The number: The World Health Organization calls a lack of vitamin A the world's top cause of blindness people could prevent. It dims the sight of hundreds of thousands of children each year, mostly where good food is scarce.

Beta-carotene isn't the whole story. Carrots and leafy greens carry two more pigments: lutein and zeaxanthin. Say those names once and let them go. What counts is where they end up.

They pool in the macula. That's the tiny spot at the center of your eye that gives you sharp, straight-ahead sight. There they soak up harsh blue light, like a pair of built-in sunglasses...

And that pooling shows up in the research. The National Eye Institute ran a five-year study called AREDS2. Adding those two pigments cut the risk of late-stage macular trouble getting worse by about 26%. The results ran in the journal JAMA in 2013.

So the carrot feeds two jobs at once. It hands you the raw stuff for night vision. And it helps guard the center of your sight for the long haul.

Here's what most people miss. Beta-carotene needs fat to reach your blood. Eat a raw carrot dry, and most of that gold slips right past you. Add a splash of olive oil or a few slices of avocado, and you soak up far more.

Cooking helps too. A light steam or roast breaks the carrot down and frees the pigment. So a soft roasted carrot with a drizzle of oil beats a raw stick for your eyes.

And the carrot has plenty of company. Sweet potato, squash, cantaloupe, and apricot all glow with the same orange pigment. Dark greens like kale and spinach bring the lutein. Eat those colors together, and your eyes get the full set.

Color tells you how much beta-carotene is packed inside. Pick carrots with a rich, deep orange, a firm body, and no soft spots. If the leafy tops are still on and look fresh, the carrot under them is likely fresh too.

Raw and dry, a carrot gives up little of its gold. Toss cooked carrots with olive oil, or dip raw sticks in hummus or guacamole. That bit of fat is what carries the pigment into you.

Carrots feed the night-vision side of things. But the sharp center of your sight wants lutein, and that lives in dark greens. Put a handful of spinach or kale on the plate right next to the carrots.

That wartime story fooled a whole country. People pictured pilots crunching carrots in the dark, when the real edge was a radar set humming in the plane.

But the funny part is what the lie got right. A plain orange root really does feed your eyes. It hands your body the raw stuff for seeing at night, and it costs about a dollar.

So slice one this week. Cook it soft, add a little oil, and eat it beside your greens. See how the evening drive feels by Friday.