And slowly I stopped being able to see past about...

this far in front of my face.

Basically, anything past...

like 10 inches in front of my eyes... is blurry.

So eventually I got glasses.

And with them, my world turns from this...

to this.

This whole experience, as inconvenient as it is, is more widespread than it's ever been.

-Myopia. -Myopia.

- Myopia, am I saying it right? -A rise in short-sightedness...

-...and the researchers actually called it an epidemic.

-...but they're still trying to figure out why this is.

Rates of myopia, or near-sightedness, or needing glasses to see things far away, have been rising for decades.

In the US, where I live, just 25% of people were myopic in 1971.

By 2004, that number was up to 42%.

And if current trends continue it's estimated that half of the world's population will be myopic by 2050.

In Hong Kong, Singapore, Taiwan, and South Korea rates are already a lot higher than that.

And a growing portion have high myopia, which the WHO categorizes as a prescription stronger than -5.

That puts them at risk of losing their sight one day.

For decades, researchers thought that whether or not you needed glasses was just a matter of genetics.

And it partly is.

Having one myopic parent doubles your odds of being nearsighted and having 2 increases the odds 5 fold.

But human genetics don't change this fast.

The abruptness of this increase suggests that that this change is environmental.

Something about the way we live today is making it harder and harder for people to see at a distance.

So what could it be?

Most people are born with eyes that are too short from front to back.

In this shape, the lens focuses images behind the retina.

That's the light sensitive tissue at the back of the eye.

That makes the eye hyperopic or farsighted.

Blurry up close and clear from far away.

But as we grow up, our eyes grow too.

Until they reach a spherical shape.

In this shape, the lens focuses light directly onto the retina and produces a clear image.

But sometimes the eye keeps growing longer.

In this shape, the lens can focus up close images onto the retina.

But at a distance, images focus at a point in front of the retina, making distance vision blurry.

So, all of us with myopia just have eyeballs that have grown too long.

The eye does not look like a basketball anymore.

It looks more like a rugby ball.

That's Seang Mei Saw.

She's a myopia epidemiologist and physician in Singapore.

It is a lifelong disease,

so once you're myopic, it doesn't regress.

So what's making more and more people's eyes grow longer than they should?

The evidence points to the way we spend time in childhood and adolescence.

That's when our eyes grow fastest.

So it's when most people's myopia develops and then stabilizes.

Though it can develop later if you abuse your vision enough.

Two factors in particular have the biggest influence.

Near work, or the time that we spend looking at things up close, and how much time we spend indoors.

In a healthy eye, muscles have to squeeze the lens in order to focus up close images onto the retina.

So some experts theorize that if your eyes grow up straining to look at things up close a lot of the time,

they'll just grow longer to reduce that strain.

But the evidence on this explanation is mixed.

The stronger explanation is time spent indoors.

Exposure to bright outdoor light stimulates the production of dopamine in the retina.

This neurotransmitter regulates the eyes growth.

Without enough dopamine, the eye doesn't know when to stop growing.

In indoors, it's hard to get enough.

The light from the sun has up to a 100,000 lux on a sunny day.

Whereas in the room, the light levels generally are only about 200 to 300 lux.

But between electronic devices and early emphasis on academics eye experts believe that

children today are growing up with a combination of too little daylight and too much time doing things up close.

And nowhere is that more apparent than in East and Southeast Asia.

Children in Asia are not spending that amount of time outside.

This could possibly be because of the education system has become much more competitive.

The children have a lot more homework,

they attend teaching centers,

and you spend more time reading and writing.

Needing glasses or contacts to see for the rest of your life is obviously inconvenient.

But in the long term, the consequences of that distorted eyeball shape can become serious.

University of Houston, Professor of Optometry, Mark Bullimore, explained this to me.

You know, you're born with a finite amount of tissue that make up the various coats of your eyeball.

Excessive elongation of that quite simply places additional stress on those structures.

The retina has been stretched so much that it starts to break,

and then sort of peel off like an old piece of paint.

The longer those eye structures are stretched the higher the risk of disorders

like myopic macular degeneration, retinal detachment, glaucoma, and cataracts.

So, we're finding this almost linear relationship between them.

The amount of myopia and the risks to your vision later in life.

We used to think about myopia as an optical defect.

Now, we think about it much more as a disease.

And the earlier a child becomes myopic the more serious their myopia can become

and the greater the risk of debilitating conditions.

Which means it's important to intervene as early as possible.

So, what does that look like?

For those who start to develop myopia, there's treatment.

First are multifocal soft contacts and glasses.

They make peripheral vision intentionally blurry, which appears to slow the progression of myopia.

Then, there's orthokeratology, or ortho-k lenses,

hard contact lenses worn only at night that reshape the wearer's cornea while they sleep,

so that they can see at a distance during the day.

And there are atropine eye drops,

low doses of a substance that temporarily paralyzes the eyes' focusing muscles,

which seems to reduce the development of myopia.

But the first line of defense is prevention.

The simplest and most effective way to prevent myopia is to get kids to spend more time outside.

In Taiwan, the government introduced a nationwide program in 2010,

encouraging schools to get students outside for 2 hours every day.

It appears to have successfully reversed a 40 year-long increase in myopia rates.

And since 2001,

Singapore has funded public education promoting time outdoors

and conducted annual vision screenings at schools.

And it seems to be working.

Right now, these rates may be higher than ever,

but the future of myopia will only look like this if we keep doing things the same way.

And we've never been in a better position to change.