How Do Our Eyes See?
Our sight is one of our most vital senses, yet our eyes are one of the most delicate parts of our bodies.
The eye is made up of several complex structures, all working together to enable us to see the world. Most of these structures are invisible to us, only seen by an eye doctor when we attend our routine eye exams.
The journey of light
We can see objects because light is constantly reflecting off them. This light enters the eye through the cornea, a layer of transparent tissue that sits in front of the iris and the pupil — the colored section and the black disc at its center.
Light moves through fluid-filled chambers in front of and behind the iris and pupil. This fluid assists the cornea to “refract” or focus the light that enters the eye.
The iris isn’t just aesthetic though. It’s also a muscle that works to contract and expand the pupil, controlling the amount of light allowed to pass through the eye’s lens and into the vitreous humor, the main body of fluid in the center.
Once the light has traveled through the vitreous fluid, it hits the retina, a layer of tissue that covers the back surface of the eye. It is the retina that decodes images and sends them to the brain via the optic nerve, ultimately enabling us to see them.
What causes poor vision?
We see perfectly well as long as our eyes maintain their spherical shape. Any change in the shape of the eyes causes light to focus either in front or behind the retina, making the images blurry.
Glasses and contact lenses adjust the direction of the light before it enters the eye to help it focus at the center of the retina. Laser eye surgery alters the shape of the cornea to achieve the same result.
In addition to farsightedness and nearsightedness, other changes in the eye can lead to a range of additional optical conditions including astigmatism, presbyopia, and double vision. These conditions require specific lens types to correct.
Our eyes can change at any time, and they can also be affected by more severe conditions like glaucoma, macular degeneration, or retinal problems. Early diagnosis of these issues is crucial for the prevention of permanent vision loss. That’s why it’s important to attend a regular eye exam.
Experts recommend an eye exam once every two years for most people. If you’re overdue your next eye exam, contact your local eye doctor and book an appointment today.