Medically Reviewed by Dr. Elisabeth Vincent Hamelin
Our eyes have an amazing vision. We see up close and far away. We also see colors. The eyelid protects and the tear fluid rinses the eye. In the brain, what the eye sees is interpreted.
- 1 Different parts of the eye
- 1.1 The cornea is sensitive to pain
- 1.2 The rainbow gives the eye its color
- 1.3 The light is let in through the pupil
- 1.4 The lens
- 1.5 The outer wall of the eye has three layers
- 1.6 Rods and pins are light sensitive
- 1.7 Macula of retina
- 1.8 Blind spot
- 1.9 The optic nerve
- 1.10 The eyelid moistens the eye
- 1.11 The tear gland keeps the eye clean
- 2 This is how vision works
- 3 This is how vision in children develops
Different parts of the eye
The eye is shaped like a small globe. The globe itself is called the eyeball. The eyeball contains a jelly-like liquid called the glass body. Around the eyeball there is adipose tissue that protects the eye. There are six small muscles around each eye. The muscles allow the eye to move and you can look in different directions.
The cornea is sensitive to pain
The outermost layer in the front of the eye is the cornea. The cornea is completely transparent. It is necessary for the light to enter the eye.
There are many pain nerves in the cornea. Therefore, it can hurt even if only a hair or a little dust falls there. It also feels uncomfortable if the cornea is dry.
The rainbow gives the eye its color
The Rainbow is below the cornea. It is also called iris. There are pigments in the rainbow that give the color to the eye. The Rainbow is shaped like a ring. In the middle of the ring is the pupil.
The light is let in through the pupil
Through the pupil the light is let into the eye. The pupil becomes smaller when it is light. In the dark, the pupil is larger to allow as much light as possible into the eye.
The lens is just behind the pupil. It is translucent, just like the cornea. The lens can change shape and become thicker or thinner. Therefore, you can see well both near and far. The lens gets stiffer and can no longer change its shape as well as we get older. Therefore, many reading glasses need.
The lens is stuck in thin threads in the so-called ciliary body. The ciliary body is an annular muscle that changes the shape of the lens.
The outer wall of the eye has three layers
In the back of the eye there is a wall around the glass body. The wall is made up of three layers called the retina, the retina and the retina. The retina is the outermost layer. It is the white part of the eye. The tendon is quite hard and holds the shape of the eye together. Inside the tendon is the varicose vein. In the retina there are many blood vessels that supply the eye with nutrients. The innermost layer in the wall of the eye is the retina. In the retina are the visual cells that allow us to see.
Rods and pins are light sensitive
There are two types of visual cells called rods and drops. The rods are the most sensitive to light. They are used when looking in the dark, but they cannot distinguish between different colors. The rods are located at the outermost edges of the retina.
The pins are color sensitive and used when the lighting is good. There are three different types of studs and they are most sensitive to blue, green and red. Color blindness or defective color vision is usually because we have too few pins that can perceive red or green. Most of the droplets are located in the middle of the retina, in a part called the yellow spot.
Macula of retina
Yellow stain is the area of the retina where we look like the sharpest. Changes in the yellow spot can lead to various diseases that affect vision.
Blind spot is an area of the retina of the eye where the nerve fibers of the optic cells join to the optic nerve. You cannot see anything in this part of the field of vision because the retina cannot receive visual impressions there.
The optic nerve
The optic nerve is the nerve that transmits information about visual impressions to the brain.
The eyelid moistens the eye
The eye is well protected in the eyelid of the skull, but it is also protected by the eyelid. The outside of the eyelid is covered with skin and the inside is covered with mucosa. The mucous membrane moistens the eye every time we blink or close our eyes. This prevents the cornea from drying out.
On the edge of the eyelid sits a row of hairs, the eyelashes. The hairspray prevents debris and dust grains from entering the eye. We automatically close our eyes if we touch the cornea or eyelashes. It is a reflex called the blink reflex.
The tear gland keeps the eye clean
Tear fluid is formed by the tear gland located above the eyeball. The tear fluid flushes over the eye as you blink. The fluid is sucked up by small ducts that go from the top of the eye into the nose.
The tear fluid has several important tasks including the following:
- It keeps the cornea free of dust and other particles that are in the air.
- It protects the cornea from dehydration.
- It is bactericidal, which protects the eye from infections.
This is how vision works
What happens when we look at something:
- The pupil lets light into the eye.
- The light rays are broken. It occurs mainly in the cornea and the lens.
- An image is created on the retina of the eye. The focus is in the yellow spot.
- The optic cells located on the retina send signals through the optic nerve to the optic center. The visual center is in the back of the brain.
- The visual center receives the signals and interprets them into an image.
This is how vision in children develops
A newborn child looks blurry, but vision develops rapidly. The vision develops by constantly stimulating the eye as the child looks at his surroundings. The visual center of the brain learns to interpret more and more detailed images. Even the sharpness of the picture is getting better.
At about four years of age, vision has developed so that the child looks almost as good as an adult. The development of vision continues until the child is about ten years old.