There’s more to your eyes than meets the, well, eyes. Each eye is made up of multiple parts that all have to work together to get the proper signals back to your brain, where the light in front of you is interpreted as colors, shapes, and movement.

At first glance, it may seem like your eyes are one singular entity, when in reality, they are a system of complex interactions and many different working parts. Here are the most vital parts of your eye and what they do to help you see.

Cornea

Your cornea covers your iris and pupil like a protective sheath. The cornea is clear and serves as the first point of contact between your eyes and the outside world. Air, light, and debris all come into contact with your cornea first.

Iris

The iris is the most personal part of your eye. This is the colored part around the pupil. If you’ve ever been told you have pretty eyes, it’s likely the iris that people were talking about. The primary function of the iris is to help your pupils contract and restrict, which is vital for letting in the right amount of light.

Sclera

This is the white of your eyes. The sclera doesn’t have the most glorious job. It doesn’t absorb light or transmit signals to your optic nerve. But what the sclera does do is still vital to the functionality of your eyes.

The sclera keeps the shape of your eye. The sclera gives your eyes their overall structure and protects the more important parts from harm. The sclera also contains all the blood vessels of your eyes. The prominence of these blood vessels is important because eye doctors look to them for signals of eye health problems.

At your annual eye exam, your eye doctor will examine your sclera and the blood vessels within it for early signs of diabetes and other diseases.

Lens

Like the lens of a camera, the lens of your eye is a transparent layer that sits behind the pupil and the iris. The lens is made primarily of water and protein. As we age, the lenses in our eyes become stiffer and lose some of their functionality. This is one reason why older people may need prescription eyeglasses.

Pupil

The pupil is light’s entry point into your eye. The pupil can constrict and dilate with the help of the iris, changing how much light can come in. Your pupils constricting helps protect your eyes from overly bright conditions that might otherwise blind you, and your pupils’ ability to dilate allows you to see better in the dark.

Your pupil can’t do it all alone, though. Your eyes can still suffer cumulative damage from sunlight exposure. Wearing 100 percent UV-resistant sunglasses can keep your eyes safe for years to come.

Retina

Your retina sits way in the back behind a layer called the vitreous humor. It is here that the magic of sight comes together. Photoreceptors in your retina read the light that passes through your eye and via a process called transduction, this light is converted into electrochemical signals. Your optic nerve transfers these signals to your brain, which is then able to interpret them as vision.

A very important part of the retina is called the macula. This area is responsible for deciphering the finer details of objects. Age and vitamin deficiencies can contribute to the degradation of the macula and compromised vision.

How do glasses help your eyes see better?

When your eyesight isn’t as sharp as it could be, this is because one or more parts of your eyes are having a hard time doing their job. Centuries ago, poor eyesight was something people just had to suffer through. Today we have prescription glasses, contact lenses and corrective eye surgeries that make squinting a thing of the past.

If you wear prescription lenses, the glasses adjust the focal point in front of your eyes. This will compensate for any troubles your eyes have with focusing images onto your retina. Wearing the correct strength is vital to the functionality of prescription glasses. If you don’t wear the right lenses, you won’t be seeing as well as you could, and you may even experience eye strain or headaches.

Prescriptions change over time, so if you haven’t been to the optometrist in a while, schedule an appointment. Your doctor will make sure your eyes are still healthy and they will also give you an updated prescription. Once you have this prescription, you’ll be able to shop for cheap online glasses that give you perfect vision at a fraction of the cost.