In 2000, a little over one person in five on Earth was short-sighted. On the current trend, by 2050 it will be one in two: close to 4.8 billion people whose distance vision blurs without glasses. In the cities of East Asia, the future has already arrived. Between 80% and 90% of young people leaving school there are short-sighted. In those classrooms, the pupil who can read the board without glasses is the odd one out.
That is not a change in genes. Genes do not move that fast, and no major gene for this kind of short sight has been found. What moved is the way we live: more years of close-up work, more hours indoors, more of the day spent looking at something a forearm's length away.
Your own version is probably smaller and more familiar. By evening your eyes feel dry and gritty, the far side of the street takes a little more effort, and the phone has crept closer to your face. Eyes evolved for distance, daylight and movement, with nothing held close for long. Most of what feels like "my eyes are getting worse" is what happens when they get none of the three, and it is also the part where you can improve your vision naturally, in how it feels and works from day to day.
Three kinds of worse
"My eyes are getting worse" covers three different problems, and each one answers to different things.
The shape of the eye. Short sight, long sight and astigmatism come down mostly to the eye's physical shape, an eyeball slightly too long, a cornea not quite round. This is what a glasses prescription corrects, and in adults no habit, food or exercise changes it. The name is old. Aristotle already noted the difference between the near-sighted and the far-sighted, and Galen called short sight myopia, from the Greek myein, to close or shut, and ops, eye: a name for the narrowed eyes of someone straining to see far.
One change in focus comes to everyone. From about 40, the lens inside the eye hardens and loses its spring and the small muscle that shapes it weakens, so close work blurs and the menu drifts to arm's length. Every eye is affected to some degree, and reading glasses are the usual answer. That is the age part of "my eyes are getting worse", and it is a smaller part than it feels.
Strain. Tired eyes, blur at the end of the day, trouble switching focus between near and far, dryness, burning, headaches. This is where habits matter most, and where they can change how your eyes feel within days.
Disease. Glaucoma, cataracts, macular degeneration, damage from diabetes, a torn retina. Food and habits can lower some of the risk, but these need checking whatever you do.
Most day-to-day eye trouble sits in the second group. Most of the disappointment with "natural vision" comes from expecting the second group's fixes to work on the first. No amount of blinking will shorten an eyeball.
What a screen does
The first thing a screen changes is your blinking. When the blink rate was measured in people at a computer, it dropped on average to a fifth of its normal rate. Every blink spreads a fresh tear film over the eye; blink a fifth as often and the surface dries between blinks. That is the gritty, burning, end-of-day feeling, and the blur that clears when you blink a few times.
The second is focus. The small muscles inside the eye change the shape of the lens to focus near or far, and hours at one fixed distance keep them working without a break. After a long day at a screen, distance can take a moment to come back.
The best-known answer is the 20-20-20 rule: every 20 minutes, look at something 20 feet away for 20 seconds. It has been tested. When 29 people with screen-tired eyes used software that reminded them to follow it, their eye-strain and dry-eye symptoms fell within two weeks. A week after the reminders stopped, the symptoms were back. The rule works while you do it, which is the catch with most rules.
The setup matters before any rule does. Put the screen at arm's length and slightly below eye level, match its brightness to the room, and make the text big enough that you never lean in. The phone is the hardest screen of all, because it is the one you hold closest and look at longest without noticing. It is probably the one you are holding now.
Dim light, on the other hand, is less of a worry than its reputation. 7 Benefits of Reading for Your Mind and Life has the reprieve for anyone told off for reading by a weak lamp: there is no evidence that it ruins your sight. Dim light can tire your eyes for a while, and the strain passes once the light improves.
Daylight
Indoor light is a small fraction of daylight. Reset Your Body Clock: Sleep Hacks, Tested, linked below, has the figures: a clear day gives 10,000 lux or more, even out of direct sun, an overcast day about 1,000, and an office only 320 to 500. Your eyes adjust so well that the office feels bright. It is not.
Children's eyes seem to need the bright end. There is preliminary evidence that long hours of daylight protect against short sight at least partly through dopamine, a signalling chemical that daylight releases in the retina. The strongest test of the idea came from twelve primary schools in Guangzhou, in China. Fascinating Ways the Summer Solstice Can Boost Your Health and Happiness has what happened when six of them added one 40-minute outdoor class to every school day: three years on, 30% of their pupils had become short-sighted, against 40% in the other six. 7 Benefits of Reading has the other side of the same coin: across more than 25,000 children, more close-up work went with slightly higher odds of short sight, and time outdoors cut the risk of it starting by more than 40%.
For adults the eye's shape is mostly settled, but daylight still does what a screen cannot. Outside, the distances change all the time: the pavement at your feet, a tree across the road, the sky. A walk outdoors is the most complete version of the 20-20-20 rule there is.
The first sunglasses were made for exactly this. From the 13th century, Inuit carved snow goggles from flattened walrus or caribou ivory, with narrow slits that blocked almost all of the sun's glare off the snow, to keep snow blindness away.
When the sun is strong, a hat and shade come first, and a wide-brimmed keeps the glare off your eyes as well as your face. With sunglasses, blocking ultraviolet matters more than darkness: dark lenses that do not can be worse than none, because the pupil opens wider behind them and lets more ultraviolet in.
The lens inside the eye has its own reason to like a hat. Cataracts, a clouding of that lens, are the most common cause of blindness in the world, and prolonged sunlight is one of their risks, along with diabetes, smoking, alcohol, obesity and long courses of steroid medicines. Smoking, alcohol and the sun are the ones in your hands. On a gentle day, though, daylight on open eyes is the point.
Dry eye
Dry eye is layered. Fewer blinks at a screen, air conditioning and heating that dry the room, contact lenses, and medicines including antihistamines, some blood pressure tablets and antidepressants can all add to it. Tiny oil glands along the edge of the eyelids, the meibomian glands, keep the tears from evaporating, and when they clog the tears dry fast.
The habits that help work on those layers. Warm compresses on closed eyes, followed by cleaning and gently massaging the lids, keep the oil glands flowing. A microwavable holds the warmth longer than a flannel from the tap.
Deliberate, complete blinks during screen work spread the tears again. A puts water back into dry indoor air while you sleep. Your eyes are not built for a climate set by an office thermostat. If you wear contact lenses, swapping to glasses for the second half of a long screen day takes one layer away. When drops are needed often, preservative-free ones avoid irritating the surface with repeated use.
Fish oil, the most popular pill for dry eye, did not survive its biggest test. In a year-long comparison, people with moderate to severe dry eye took fish oil or a dummy capsule of olive oil. Both groups improved by about the same amount, on symptoms and on every measure of the eye's surface. The fish on the plate is still worth eating, for reasons coming below. The capsule for dry eye is not.
Blue light
Blue-light glasses are sold for screen strain, and they have been checked. A review of 17 small tests found they may make no difference to eye strain, and found nothing to show that they protect the macula. They do make the screen look slightly yellow.
Blue light matters at the other end of the day. In the evening, bright and blue-rich light tells the body clock that it is still daytime and delays sleep, and Reset Your Body Clock has what amber lenses and dim, warm light did for that. Sleep is when tired eyes recover, so a late screen costs you twice: a later night and a drier morning.
Food for the eyes
The retina is one of the most demanding tissues in the body, and what it is built from comes from the plate.
Eggs first. Lutein and zeaxanthin are yellow pigments that collect in the macula, the small central patch of the retina that gives sharp vision, where they filter light. The usual advice sends you to leafy greens. When ten men were given about the same amount of lutein from spinach, from a pill, from a second kind of pill and from eggs, the lutein in their blood rose most after the eggs.
And it reaches the eye. When 24 women ate eggs on most days of the week for 12 weeks, the pigment in their macula grew denser, and their blood cholesterol did not change. In the comparison group, given a sugar pill instead, it went up. The sugar pill did more to cholesterol than the eggs.
Carrots are a war story. The idea that carrots help you see in the dark was spread in the Second World War as propaganda, to explain how British pilots kept winning air battles at night. The real reason was radar.
Liver for the dark. Night blindness, the struggle to see in dim light, is the first sign of running short of vitamin A, and retinol, the ready-made form, comes from liver, fish oils and dairy. Worldwide, vitamin A deficiency still causes hundreds of thousands of cases of childhood blindness.
Fish for the retina. DHA, an omega-3 fat, is a major building block of the retina, as it is of the brain. Fatty fish carries it ready-made.
Sugar against the macula. In 4,099 older people checked for macular degeneration, those whose diets had a glycaemic index above the middle, the diets that sent their blood sugar up fastest, had 49% more of the advanced disease. The authors estimated that a fifth of the cases might not have happened on a diet below the middle. Diabetes takes the same road further: damage to the retina from diabetes is a leading cause of blindness in rich countries.
Smoke against the macula. Smoking raises the risk of macular degeneration two to three times, and it is the strongest risk for it that you can change.
The eye vitamins
The famous eye-vitamin formula comes from a large test of 3,640 people aged 55 to 80. Over about six years, a high-dose mix of vitamins C and E, beta-carotene and zinc cut the odds of advanced macular degeneration in people whose eyes were already at risk. Copper and Your Health: Too Little, Too Much, and Why has why copper was added on purpose: zinc in those amounts drains it.
The follow-up, in 4,203 people, added lutein and zeaxanthin, or omega-3s, to the formula. In the main analysis neither made a measurable difference. What it did turn up was a warning: more lung cancers in the group taking beta-carotene, mostly in former smokers, which is why the authors suggested lutein in its place.
So the formula treats a particular eye at a particular stage. Its benefit showed in eyes already at risk, and there is no such result for healthy ones. For everyone else, the eggs, liver and fish above are the better bet, without the doses.
Red light
One finding is new enough to be interesting and small enough to be careful with. In 2021, people aged 37 to 70 looked into a deep red light, at 670 nanometres, for three minutes in the morning. For about a week afterwards, their colour vision was sharper, closer to that of younger eyes. The idea is that red light helps the ageing energy factories in the retina's cells work better.
The same light in the afternoon, tested in six people, did nothing. The numbers are small, the effect is on colour contrast, which is not the same as everyday sharpness, and nobody yet knows what repeated use does over years. It is a finding to watch. It is not yet a reason to buy a device.
Eye exercises
Eye exercises promise more than they can deliver and less than their critics claim.
They cannot change the eye's shape. The Bates method, the best-known system of vision exercises, rests on the idea that tense muscles squeeze the eyeball out of shape, and there is no evidence that any exercise alters it. An eyeball does not do push-ups. Adults who feel their vision is clearer after weeks of exercises are usually feeling less strain, which is worth having, but the prescription stays the same.
One kind of exercise does have evidence behind it. Convergence insufficiency is a problem in which the eyes struggle to turn inwards together for close work, which makes reading tiring and can cause double vision. When 221 children aged 9 to 17 with the condition were given different treatments for 12 weeks, 73% of those who had supervised exercises in a clinic, practised at home as well, improved, against 35% of those given a dummy version.
The rest is plain rest. Shifting focus between near and far, palming the eyes with warm hands in the dark, and deliberate blinking all give tired eyes a break. They cost nothing, and that is all they need to do.
When to get checked
Some signs need a check the same day: floaters appearing suddenly or multiplying, flashes of light, a dark curtain or shadow moving across your vision, sudden blur, or sudden severe pain in the eye. Floaters, flashes and a curtain are the classic signs of a detaching retina, and sudden pain with blurred vision and halos around lights can mean a sudden rise in pressure inside the eye. Both are emergencies.
Slower changes deserve an appointment too: vision that has changed noticeably over a year, reading that needs more light than it used to, or dry, irritated eyes that the habits above have not settled. And some of the serious eye diseases give no warning at all. Glaucoma has been called the silent thief of sight, because the vision goes slowly and early on there are no symptoms. Damage to the retina from diabetes is often just as quiet, which is why Iceland, Ireland and the United Kingdom run national screening programmes for it. A pressure check and a look at the back of the eye find what you cannot feel.
One in two
By 2050, one person in two may need glasses to see into the distance. Most of that is being decided indoors, at arm's length from a screen, and most of the strain you feel at the end of the day is decided the same way.
Your prescription is mostly settled. What your eyes go through every day is not. And that part is yours.
This week, take every phone call outside.
Curious what else your face gives away? What Your Eyes, Tongue, Nails, Skin, and Breath Are Telling You About Your Health — why your iris can open a passport gate and cannot report on your liver, the colour in the whites of the eyes that beats the textbook sign of anaemia, the yellow patch that predicts heart attacks whatever your cholesterol, and what a weak handshake predicts.
Still on a screen late at night? Reset Your Body Clock: Sleep Hacks, Tested — what sets the body clock, why morning light beats sunglasses, amber glasses against red bulbs, and the meals that moved a clock by nearly six hours.
Know someone who squints at a screen all day and blames their age? Send them this, and a hat.
Disclaimer: This article is general information. For advice about your own health, talk to a qualified health professional, especially if your vision changes suddenly, if you have diabetes or a family history of glaucoma, or before taking high-dose eye vitamins. The warning signs above need a check the same day.
Affiliate Disclosure: This article contains affiliate links. As an Amazon Associate, All For Life earns from qualifying purchases, at no extra cost to you. We only link to products we would recommend without the commission.
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