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"How do eyeglasses work?" Glasses help focus our vision by using lenses to correct refractive errors in the eye. Simply put, glasses help us see better by making sure light enters our eyes the right way. This isn’t really a new concept — we’ve been using lenses to help us see things for almost 2000 years! While early lenses focused mainly on magnifying small or distant objects, modern glasses work a little differently. Doctors measure our eyes and note where they need improvement. They then compile all of that information into what we call a prescription.Using this prescription, glasses companies can modify and add lenses to glasses frames in order to help correct your eye’s unique problems. The most common refractive errors include myopia (nearsightedness), hyperopia (farsightedness), presbyopia, and astigmatism. Exactly how a pair of glasses works depends on what type of eye condition(s) they’ll be correcting.

People who can see things up close, but have trouble seeing things far away typically have what’s known as nearsightedness. Myopia, the medical term for nearsightedness, is when light comes to a focus before reaching your retina (your retina being the part of your eye that records what you’re seeing and sends it to your brain to be processed — kinda like film!). This causes things in the distance to look blurry. To correct for myopia, glasses use convex lenses in order to project light far enough so that it reaches your entire retina.

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If you can see things far away but have trouble seeing things up close then there’s a good chance you’re farsighted. Farsightedness, or hyperopia as it’s medically known, is caused when light comes to focus behind your retina. This makes things up close look blurry but allows things far away appear clear. To fix this, glasses for hyperopia use concave lenses to adjust how far light is projected into your eye, making sure it’s focused correctly on your retina.

So how do glasses help people with presbyopia? First, let’s talk about what presbyopia is. Presbyopia is when your eyes have trouble focusing on things up close due to their loss of elasticity. Yup, that’s right — your eyes change shape when they try to focus. However, as you age, it becomes more difficult for your eyes to change shape. So, what kind of glasses are best for presbyopic eyes? That depends! If you only need correction for seeing things up close, then your glasses will only need to correct for seeing things up close (similar to but not the same as hyperopia/farsightedness). However, if you have trouble seeing things both near and far, then you will probably need multifocal lenses.

How do glasses with multifocal lenses work? Whether they’re bifocals or no-line, progressive lenses, both options combine multiple prescription distances into one lens. Bifocals glasses have lenses that are divided into two sections; the main portion to correct for distance, while a smaller portion in the bottom of the lens is used to facilitate near sight. Progressive lenses take it a step further by incorporating corrections for near, far, and mid distances all into one lens.

On top of correcting for myopia, hyperopia, and presbyopia, glasses also work by correcting problems caused by astigmatism. Astigmatism is when the surface and curve of your eye aren’t spherical. What does this mean? Due to the “irregular” shape of an eye with astigmatism, when passes light thought, it refracts into multiple focal points. This causes blurred vision, eyestrain, and other symptoms associated with astigmatism. To correct for the irregularities on the surface of the eye, glasses with lenses for astigmatism work by grinding the lens into a more oval shape.

We hope we've answered any lingering questions on how do eyeglasses work. When it comes down to it, most eyeglasses work in a similar way, but how your eyeglasses work really depends on what type of vision correction your eyes need. Not sure what type of correction your doctor prescribed? Learn more about how your prescription works and what all the different types of corrections there are in EyeBuyDirect’s guide on how to read your prescription.

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