Lily Miller The iris is the colored part of the eye surrounding the pupil. It controls the pupil’s size to automatically control the amount of light that enters the eyes.
The main stimulus that our eyes use to interpret the world is light. Both insufficient and excessive lighting can impair vision.
The iris and pupil are important components of vision. No matter how much light is present outside, they can control how much light enters the eye and enable us to see.
We will discuss how does the iris get its color, conditions that may alter eye color, and how do we see what we see?
Table of Contents
What is the Iris?
Between the cornea and the lens, the iris is a small, elongated, and highly pigmented membrane. It separates the anterior chamber of the eye into an anterior and posterior chamber.
The pupil, the opening in the middle, is present. To control how much light reaches the retina, the iris’ muscles contract and expand the pupil.
The hue of a person’s eyes is inherited. Melanin, a dark brown pigment found in the iris, affects both the pattern and quantity of the eye’s color.
The most melanin is found in eyes that are dark brown. Less is present in the eyes of light brown, hazel, and green people. There is less in eyes with lighter hues like blue and gray.
How Does the Iris Get Its Color?
The color scheme of your skin and hair is genetically related to the hue of your iris.
The pigments that give plants and animals their color also give our skin and hair their color. The creation of your eyes’ color can also be attributed to a pigment known as melanin.
Your eye color is determined by the quantity and quality of melanin found in the iris’s outermost layers. Melanin comes in shades of black, brown, red, and yellow.
The iris has a color spectrum that includes green, hazel, brown, and shades of blue that go all the way to deep brown.
The color of our eyes depends on genetic variations. Most of those genes are involved in the production, transport, and storage of melanin. Your eye color is based on how much melanin is present. Very little melanin is found in blue and gray eyes, whereas a little more melanin is found in green, hazel, or light brown eyes. Amber, medium, and dark brown eyes are the ones with the most melanin.
In case you were wondering, the pupil is normally black, but it can appear red when a camera flash illuminates the retina. The white part of the eye, known as the sclera, usually stays white, though certain medical conditions can cause it to turn yellow or blue, and inflammation can cause it to turn red or pink.
Eye Color Role Genes
The color of the eyes is largely determined by two genes on one chromosome. DNA, the genetic material responsible for each person’s uniqueness, is contained in chromosomes. The color of the eyes is also influenced by numerous other genes.
Although a child’s eye color may be predicted by the parents’ or other relatives’ eye color, genetic differences may cause a child to have blue eyes when their parents have brown eyes. To put it another way, it can be challenging to foretell a baby’s eye color.
“Though we once believed that eye color was determined by a relatively straightforward pattern of inheritance, scientists have recently discovered that it is actually caused by numerous genes working together. What’s more, tiny tweaks on a gene can result in different shades in the iris,” according to Popular Science.
Although the amount of change in eye color after six months decreases, it takes about a year for melanin to do its job of determining what a baby’s eye color will be. Even as adults, eye color can alter.
Read about What Is Eye Refraction Test?
Conditions That May Alter Eye Color
The color of some people’s eyes may be abnormal from birth or develop over time.
The percentage of people with eyes that are two different colors, such as one brown and one blue, is less than 1%. Uneven melanin concentration and distribution are the result of this condition, known as heterochromia. Heterochromia is frequently genetic, but it can also be brought on by trauma, inflammation, or glaucoma.
A group of genetic disorders known as Waardenburg syndrome affect some newborns. This syndrome, which is frequently attributed to genetic mutations, has been linked to hearing loss as well as color changes in the eyes, skin, and hair. Pale blue eyes or two different eye colors are common in Waardenburg syndrome patients. Parts of one eye may occasionally have two different colors.
People who have albinism, a different condition, have little to no pigment in their eyes, skin, and hair. The eyes of those with albinism can occasionally appear red or violet.
How Do We See What We See?
The cornea, a transparent tissue layer at the front of the eye, is where light enters the eyeball after reflecting off of objects. The pupil—the dark opening in the middle of the colored part of the eye—allows the cornea to receive and bend light rays that are widely divergent.
According to the brightness of the light entering the eye, the pupil appears to naturally dilate or enlarge. In reality, the iris, a ring of muscles in the colored part of the eye, regulates the pupil opening according to the brightness of the light. (Therefore, the iris is working when a pupil appears to dilate or enlarge.)
The lens of the eye allows passage of the corrected light. The lens, which is situated behind the pupil, automatically corrects the light’s path so that it focuses sharply on the retina, the receiving area at the back of the eye.
Amazing photoreceptor-packed membrane (also referred to as the “rods and cones”), the retina converts the light rays into electrical impulses. These then make their way to the brain via the optic nerve at the back of the eye, where an image is subsequently perceived.
The Main Parts of the Human Eye
- Cornea: transparent tissue covering the front of the eye that lets light travel through
- Iris: a ring of muscles in the colored part of the eye that controls the size of the pupil
- Pupil: an opening in the center of the iris that changes size to control how much light is entering the eye.
- Sclera: the white part of the eye that is composed of fibrous tissue that protects the inner workings of the eye
- Lens: located directly behind the pupil, it focuses light rays onto the retina
- Retina: membrane at the back of the eye that changes light into nerve signals
- Rods and cones: special cells used by the retina to process light
- Fovea: a tiny spot in the center of the retina that contains only cone cells. It enables us to have sharp vision.
- Optic Nerve: a bundle of nerve fibers that carries messages from the eyes to the brain
- Macula: a small and highly sensitive part of the retina responsible for central vision, which allows a person to see shapes, colors, and details clearly and sharply.
Summary
The iris is more than just the color of one’s eyes. It is essential to vision because it helps us see in different lighting conditions and sharpen our focus on objects.
Numerous factors, including hereditary traits, viral infections, wounds, and trauma, can cause conditions that affect the iris. They occasionally appear out of nowhere.
Anyone who believes they may have any of the aforementioned conditions or is bothered by something involving their irises may want to think about speaking with an eye doctor.
