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How Our Eyes See the World.

Our eyes are amazing. They process an incredible amount of information every second- so, how do they actually 'see' all there is to see?

Closeup of eye with rainbow light across the center
The human eye can distinguish about 1 million colors!

The human eye is a remarkable and complex organ that allows us to see the world around us.

Chances are, you aren’t thinking about the myriad of processes that are happening moment to moment just as we are looking at things, from reading to watching a favorite show to engaging in activities. Did you know that the human brain can process 11 million bits of information every second? Even though much of that processing is happening subconsciously, that doesn’t make it less impressive!

Much of the information our brain processes takes place in the eyes.

One of the most impressive things about the eye is its ability to see colors and images. Another fun fact: the human eye can distinguish about 1 million colors. Let’s explore how the eyes see color and images and the science behind it.

The Eye and Light

Before we dive into how the eyes see color and images, it's important to understand how the eye works with light. Light is made up of electromagnetic waves that travel through space. When light enters the eye, it passes through the cornea, which is the clear, outermost layer of the eye. The cornea helps to focus the light onto the lens, which further focuses the light onto the retina, located at the back of the eye.

The Retina and Color

The retina is the layer of tissue at the back of the eye that contains cells called photoreceptors. These photoreceptors are responsible for detecting light and sending signals to the brain. There are two types of photoreceptors in the retina: rods and cones.

How Rods and Cones Work

Rods are one of the two types of photoreceptor cells located in the retina of the human eye, responsible for detecting light and dark, as well as movement. They are more sensitive to low levels of light, making them especially important for vision in dimly lit environments.

When light enters the eye and reaches the retina, it is absorbed by the rhodopsin molecules in the rods. This absorption causes a chemical reaction that leads to the generation of an electrical signal. This electrical signal is then transmitted through a network of neurons in the retina, ultimately reaching the brain via the optic nerve.

Illustration of eye, optic nerve, ganglion cells, bipolar cells, rods, and cones

Rods are not sensitive to different wavelengths of light, which means that they cannot distinguish between different colors. Instead, they are more sensitive to differences in brightness or contrast. This is why we can still see objects in black and white in low-light conditions.

The high sensitivity of rods to low levels of light also means that they can become saturated when exposed to bright light, making it difficult to see in such conditions. This is why when you move from a dark environment into a brightly lit one, it takes some time for your eyes to adjust and for the rods to recover from the saturation.

Illustrated chart showing wavelengths of visible light
Wavelengths of light on the visible spectrum

Cones, on the other hand, are responsible for detecting color. There are three types of cones, each of which is sensitive to a different range of wavelengths of light. The three types of cones are known as S cones, M cones, and L cones, which stand for short, medium, and long wavelength cones, respectively.

S cones are most sensitive to short wavelengths of light, which correspond to blue colors.

M cones are most sensitive to medium wavelengths, which correspond to green colors.

L cones are most sensitive to long wavelengths, which correspond to red colors.


When light enters the eye and reaches the retina, it is absorbed by the pigments in the cones. These pigments undergo a chemical reaction that generates an electrical signal, which is then transmitted through a network of neurons in the retina. The electrical signals from the cones are combined and processed in the brain to create the perception of color.

In addition to detecting color, cones are also responsible for detecting fine visual detail. Cones are most densely packed in the center of the retina, an area called the fovea, which is responsible for high-resolution vision. This is why when we want to see something in detail, we tend to look directly at it to use the fovea, where the concentration of cones is highest.

Color Perception

Color perception is a complex process that involves not only the photoreceptors in the retina but also the brain. The brain takes the signals sent from the photoreceptors and processes them to create the perception of color.

One important aspect of color perception is color constancy. Color constancy is the ability of the brain to perceive colors as being consistent even when the lighting conditions change. For example, if you look at a red apple under a bright white light and then under a yellow light, the apple will still appear red, even though the lighting conditions have changed. This is because the brain adjusts to different lighting conditions and still perceives the color as being the same.

Images and the Brain

The retina not only detects color but also forms images. When light enters the eye and is focused onto the retina, it forms an upside-down image of the visual field. The brain then takes this image and processes it to create the perception of the visual field as we see it.

cross section of eye seeing candle
illustration showing the eye inverting images

The processing of visual information in the brain is a complex process that involves several different areas of the brain. The primary visual cortex is responsible for processing basic visual information such as lines, shapes, and edges. Higher-level areas of the brain then process this information to create more complex visual perceptions, such as recognizing faces or reading words.

Color Blindness

While most people have normal color vision, some people have a condition called color blindness. Color blindness is a genetic condition in which one or more types of cones in the retina do not function properly. This can result in difficulty distinguishing between certain colors or seeing certain colors at all.

There are several types of color blindness, but the most common type is red-green color blindness. This is when the M and L cones in the retina have a similar response to certain wavelengths.

Examples of color blindness
Examples of how color is perceived with color blindness

Treatment Options for Color Blindness

Currently, there is no cure for color blindness, and no treatments have been proven to completely restore color vision. However, there are some options that can help people with color blindness better distinguish between colors and improve their ability to perceive colors in certain situations.

One option is the use of color-correcting lenses, which are specially designed glasses that filter out certain wavelengths of light to enhance color perception. These lenses can be effective for some people with color blindness, particularly those with red-green color blindness.

Another option is the use of electronic devices that enhance color perception, such as color vision correction software or apps that adjust the colors on a screen to make them more distinguishable.

It's important to note that these options may not work for everyone with color blindness, and their effectiveness can vary depending on the type and severity of the color vision deficiency. It's also important to consult with a qualified eye doctor or vision specialist before trying any treatments or devices for color blindness.


At Rivertown Eye Care, out team is dedicated to making sure you have the best vision possible so you can enjoy the world around you in all its vibrant colors. The first step to eye health is scheduling your annual exam. Call Rivertown Eye Care today!

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