If you saw these pictures in a gallery, you might think the glass was smudged.

Delicate Arch in Arches National Park. Original image by David Hiser/Wikimedia Commons.

The right sides of these pictures are all blurry and kind of grey.

"Napoleon Crossing the Alps" by Jacque-Louis David. Image via Wikimedia Commons.

You'd obviously want to get someone to clean it up!

But what if the smudge was inside your eye?

Inside your eyes are natural lenses, like the lens of a camera. The lens focuses light onto the back of our eyes, where specialized cells interpret the image and send that information to the brain. Because all the light we see has to go through the lens, our bodies naturally make it transparent.

Sometimes, however, proteins in the lens start to clump together, forming a small cloudy area that destroys that carefully constructed lens transparency, like replacing a camera lens with a piece of frosted glass. This cloud is what's known as a cataract, and over time, it can spread to cover the entire lens in the eye.

Congenital cataracts. Image from National Eye Institute, National Institutes of Health/Flickr.

When this happens, cataracts cause our vision to become blurry and washed out. They can also make light glare really bad and give some people double vision.

More than 22 million Americans over 40 already have cataracts. By the time we turn 80, most of us will have them in some form.

Cataracts are the leading cause of blindness in the world and mostly happen to people as we age. They can also be found in children and younger adults due to congenital conditions, injury, or illness. About one in every 250 kids is born with or develops cataracts at young age.

Treatments for cataracts do exist. The current solution generally either involves stronger glasses or, if the vision loss is bad enough, surgery to replace an old, cloudy lens with a transparent plastic one.

A young person in Bali recovers from cataract surgery. Image from Agung Parameswara/Getty Images.

But cataract surgery does sometimes come with complications, and some types of the plastic replacement lenses sacrifice the flexibility of our biological lenses — they have trouble focusing on nearby stuff, for instance, and don't work super well in children.

Cataract surgery might be about to get a neat sci-fi upgrade thanks to new research involving stem cells.

Stem cells are a special kind of cells found in our bodies that can transform themselves into different types of cells (like eye cells or brain cells or kidney cells).

They've been a hot area of research, from anti-aging ideas to straight-up regenerating limbs.

Stem cells magnified on a computer screen. Image by Spencer Platt/Staff/Getty.

Two groups of researchers recently published studies investigating if stem cells could help re-grow biological lenses.

One group of researchers in Japan and the U.K. recently used human stem cells to grow cells from many different parts of the eye.

The scientists took human stem cells and coaxed them into transforming into eye tissue. They found that they could successfully make the cells divide into different layers as they grew.

Image from NPG Press/YouTube.

What's cool is that each layer corresponded with a different part of the eye. Cells from the first layer, for example, could potentially become part of the nerve-rich tissue at the back of the eye while cells from between the second and third layers could become the lens, and cells from layers 3 and 4 could become parts of the cornea.

The researchers were even able to successfully transplant the new stem-cell-grown corneas into rabbits. This technique could one day help doctors replace many different parts of people's eyes as they become damaged, although a lot of work needs to be done before we see any tests in humans.

Another research group, meanwhile, experimented with a surgical technique designed to help children regrow new lenses.

The technique is deceptively elegant because it doesn't require any new technology, just a twist on existing techniques.

“This is just a change in a surgical procedure,” said James Funderburgh, a cell biologist at the University of Pittsburgh in a Nature press release. “They are not putting in an artificial lens: they are just letting the lens regrow.”

In this new technique, the surgeons use a smaller-than-normal incision to remove the patient's cloudy lens but don't implant a plastic one afterwards. That's because after the lens is removed, some stem cells are naturally left behind in the patient's eye, and it turns out that, by leaving them alone, the body can use those stem cells to grow a brand new lens.

This technique is slower than traditional methods because the child's eye needs about three months to grow a new lens. But the benefit is that the lens won't grow cloudy over time, like some artificial ones do, and the surgery has a much lower rate of complications.

Sunglasses help protect these kids' eyes a few days after cataract surgery. Image from Chris Jackson/Getty Images.

In fact, this technique was so successful, they've even used it on 12 human babies. It's been two years since some of them had the procedure done, and so far, the results seem promising. While this particular technique may not be as useful for older adults (whose cells grow more slowly), it could restore sight to a lot of young people.

“Even if it’s only for kids, it’s fantastic,” said Funderburgh.

Cataracts are one of the most common vision problems in the world, but these cool new tools could help those living with them see the world a whole lot more clearly.