How the Eye Works

Mar 18, 2022 | Vision

The eyes are an intricate and important part of the human body. They allow us to see the world and take in our surroundings. While most people do not give how vision works much thought, a lot happens in a short amount of time to allow humans to see.  

Our Montgomery County optometrists are here to help explain how the eye works and what goes on behind the scenes to help us see.

Parts of the Eye

Before you dive into how the human eye works, it can be helpful to know some of the major parts of the eye and their primary functions. While not a list of every structure of the eye, here are some of the major players when it comes to how eyesight works. 


The cornea is the transparent, protective outer layer of the eye. It helps to focus light that enters the eye.


The dark circle in the center of the eye, the pupil is an eye structure that helps to determine the amount of light entering the eye. When there is no light present, the pupil will expand, but in brighter conditions, the pupil will contract to limit light.


The iris is a muscular membrane and the part of the eye that is responsible for regulating how much light gets to the retina by changing the size of the pupil. It also determines your eye color.

Crystalline Lens
The lens is a transparent eye structure made mostly of proteins that plays a role in bending and focusing light.


The retina is a layer of tissue located in the back of the eye that is responsible for sensing light and sending signals to the brain that are later translated into what you see.

Optic Nerve

The optic nerve is a bundle of nerve fibers that carries messages from the retain to the brain in the form of electrochemical impulses. The brain makes sense of these signals and translates them into what we see.

How Vision Works & How the Eye Sees

Vision is all about the eyes’ ability to detect and refract light along with the brain’s ability to convert these messages into images we can understand. This process includes a series of steps as well as several parts of the eye and the brain working together. Vision problems usually involve a breakdown in how the eye works such as damage to an eye structure.  

The first step in how an eye sees is light detection. Light from an object will enter the eye and pass through the cornea. At this point, the cornea will bend, also known as refract, the light to focus it. Depending on the brightness, the iris will expand or contract the pupil to let in the appropriate amount of light.

After passing through the cornea, the light is bent again by the lens for refinement and focused onto the retina in a process called refraction. Most vision problems occur when something goes wrong with this process.

The last step in how we see is sensory interpretation. Once the light is captured by the retina, it stimulates the release of electrochemical impulses that travel along the optic nerve to the brain. When these signals reach the visual cortex located in the back of the brain, they are deciphered and translated, so we can make sense of the visual information. Initially, the image is upside down, so part of this process includes inverting the image so that it is right-side up.

Now that you know how the eye works, your next concern should be if your eyes are working correctly. Even if you don’t believe you are experiencing any vision problems, there may be issues under the surface that could go unnoticed until your vision is severely impacted. To avoid irreversible damage, our eye exams in Glenside and Spring House can detect damage to eye structures before they become serious. Contact us today to make your appointment.

Tips for Maintaining Good Vision as You Age 

Tips for Maintaining Good Vision as You Age 

As we age, our eyes undergo changes that can affect our vision. Conditions like presbyopia, cataracts, macular degeneration, and dry eye become more common. However, there are steps we can take to maintain good vision and ensure healthy eyes as we grow older. In this...