What is Sight and the Eye? | Types, Definition, Structure, Function & Facts

What is Sight and the Eye?

Sight is one of the five senses that help us gain information about what is happening in the world around us. We see through our eyes, which are organs that take in light and images and convert them into electrical impulses that our brains can understand.

How do we See?

When we see something, what we see is actually reflected light. Light rays bounce off objects and enter our eyes.

Our Amazing Eyeballs: Pupil and Iris

The eyes are wonderful and complex organs. In order for us to see, light enters our eyes through the central black spot, which is essentially a hole in the eye called the pupil. The pupil can change size using the colored part around it, a muscle called the iris.

By opening and closing the pupil, the iris can control the amount of light entering the eye. If the light is too bright, the pupils will narrow to let less light in and protect the eyes. If it’s dark, the iris opens the pupil to let more light into the eye.


When light enters our eyes, it passes through the fluid and reaches the retina at the back of the eye. The retina converts light rays into signals that our brains can understand. The retina uses light-sensitive cells called rods and cones to see. Rods are very sensitive to light and help us see when it’s dark.

Cones help us see colors. There are three types of cones that each help us see a different color of light: red, green, and blue.


In order for light to be focused on the retina, our eyes have a lens. The brain sends feedback signals to the muscles around the lens to tell it how to focus the light. Just like how a camera or microscope works, when we adjust the lens we can bring the image into focus. When the lens and muscles cannot focus light properly, we eventually need glasses or contact lenses to help with the eyes.

Off to the Brain:

The rods and cones of the retina convert light into electrical signals for our brain. The optic nerve transmits these signals to the brain. The brain also helps with eye control to help the eyes focus and control where you are looking. Both eyes move together with speed and precision to allow us to see with the help of our brain.

Why two Eyeballs?

With two eyeballs, our brains receive two slightly different images from different angles. Although we only “see” one image, the brain uses these two images to give us information about the distance of an object. This is called depth perception.

Fun Facts about the Eye

The image on the retina is actually upside down from the actual image. Our brain calculates it for us and vice versa, otherwise we get really confused!

The cornea is a transparent layer in front of the eye that helps protect it.

We have a blind spot where the optic nerve connects to the retina.

Tears help keep our eyes clean, but scientists don’t really understand why we cry when we’re upset or upset.

The average person blinks 15 times per minute.

About eight percent of men are colorblind, but less than one percent of women.

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