You’re out and about, and your friend points out a beautiful bird they see up in a tree. You look where they’re pointing, but you can’t see a bird, despite their insistence that one is out there. Seconds later, the bird flies from the tree towards you and your friend, and suddenly, it’s much clearer. You realize your sight might not be what you thought it was, so you go to your friendly neighborhood Winnipeg optometrist. They check your eyes out, and you learn that you’re nearsighted – you have myopia.

The most important thing to know is unless your optometrist tells you otherwise, you’re not in any grave danger; myopia isn’t a disease, in the traditional sense, your eye is just differently formed than most. The same is true of hyperopia, farsightedness, and if you’ve ever wondered how someone would be able to see far but not near, you’re in the right place.

To understand these conditions, it’s important to know a bit about the anatomy of the eye. In brief, the front part of your eye exists to regulate and focus the amount of light coming onto the retina. The retina is a nerve layer covering the back of the eye, tasked with sensing the light from the rest of the eye and transmitting that information through the optic nerve to the brain, where the image is interpreted.

Both hyperopia and myopia are caused by your eye being too short or too long, respectively. When your eye is too short, the light coming off of nearby sources is focused past the retina by the lens and cornea, resulting in a blurry image. Conversely, when you have myopia things that are far away are focused in front of the retina, again creating a blurred image of what you should see.

Glasses and contact lenses work by changing how light is focused in the eye. In the case of myopia, glasses will cause light to be more refracted; that way, when the light is focused, it will end up right on the retina, where you want it. Corrective eyewear for farsighted folk will instead cause the light to converge, enabling it to focus on the retina instead of going past it. It’s fair to say myopia and hyperopia are caused by problems with where the focus point ends up on your eye, so shifting how focused the light is when it reaches your cornea and lens can correct the problem. It’s also easy to see why you need a firm grasp of physics in order to become an optometrist; changing how light refracts so your eye can focus better is a complicated proposition!

It’s important to visit your optometrist regularly; the eyes of children continue to develop as they age, so their vision can change continually during that period. Even if you don’t have hyperopia or myopia, a visit is important; eye disease can develop in people with 20/20 vision, because as we’ve seen, it’s the shape of the eye, and not a disease, that causes people to need glasses.