Eye Anatomy

Learn the main anatomical parts of the eye and how the eye works.

Everything Eye

Anatomy

At EyeDefense Vitamins we are not only dedicated to providing you with products sourced from the finest quality ingredients. We also provide you with the latest updates and scientific breakthroughs concerning eyes.

PUPIL
The pupil looks like a black hole in the middle of your eye, but actually it is the lens of the eye that you are seeing.
The pupil is more than just a round hole in the iris! It is an important part of the eye.
We are used to thinking of a cell phone as a camera and so we can miss the importance of the “aperture” that is used to focus in a traditional camera. The pupil works as that aperture in the “camera” that is your eye!
The pupil can constrict (get smaller) and dilate (get bigger), allowing less or more light into the eye. So, when you go outside into the bright light the pupil will constrict and it will dilate when you go back inside, in the relative dark. And by doing so it focuses the image you are looking at on the retina in the back of the eye.

CORNEA
The cornea is the clear part of the eye that acts as a protective cover. It protects the iris (the colored part of the eye), the pupil and the lens. Compare the cornea to the "clear crystal" of a watch protecting the hands of the watch.
But the cornea is more than just protection!
It has 5 layers and is very complex in its architecture. It is has a key refractive function: it helps focus light on the retina.
The cornea must stay wet on the surface so that it is smooth (that is why we blink) and it must remain “dry” on the inside so that it can remain clear.
The cornea can become scratched (corneal abrasion), infected (corneal ulcer) or dry.
IRIS
The iris is the most identifiable part of the eye because it gives the eye its “color”. When people have brown eyes their iris' are thicker because they have more pigment. When you have blue eyes you have a thinner, more translucent iris. This is why people with lighter eyes sometimes are more light sensitive because more light is seeping through the iris to the back of the eye.
The iris controls the size the pupil. As we have discussed above, the size the pupil allows the eye to focus the image on the retina in the back of the eye.

LENS
You can see the lens of the eye when you look into someone’s pupil, but only a small part of the entire structure is visible. The lens is like the lens of camera, it changes shape to focus light.
The lens also affects every person over the age of 40! As the lens ages it no longer changes shape as quickly or easily. Focusing on near objects, when reading a book for example, becomes more difficult. This is why reading glasses are needed as the lens ages.
The lens is famous because of cataracts. When you get older the lens, which is naturally clear, begins to take on a yellow tinge that is called a cataract. When the cataract is yellow enough the person becomes aware of it because images will no longer clearly focus.

CILIARY BODY
The ciliary body has very important functions that the eye could not “live” without. First and foremost, the ciliary body makes the fluid that keeps the eye inflated. The ciliary body is constantly making fluid and this fluid is constantly being drained from the eye, so that there is a balance that gives the eye its normal pressure.
If the eye is not draining its fluid normally the pressure can build up inside the eye. This is called glaucoma. Many glaucoma drops work by suppressing the function of the ciliary body in its fluid making capacity.
The ciliary body is also the origin of the so called “zonules” that move the lens and allow it to change shape and thereby focusing the light on the retina.
CHOROID
The retina is such an important tissue of the eye that it actually has two blood supplies! This is remarkable for a tissue that is thinner than a wet napkin. One of the blood supplies feeds the so called outer retina. When you look at a picture of the retina these arteries and veins are very obvious, even to the untrained eye.
The choroid is the other blood supply. It is under the retina, serving the inner retina, and because its vessels are not seen on a photograph, it is harder to understand its great importance. It is critical to the very metabolically active inner retina that is processing light constantly as we see.
We will talk about wet and dry macular degeneration in another section, but it is from this choroid that abnormal blood vessels spring and when they leak or break, they cause wet AMD.

RETINA
The retina is a complex tissue that lines the back of the eye like wallpaper. It is the “film” in the camera that is your eye. The retina is so fascinating because of its multiple layers of integrated cells that all miraculously function to send light impulses to the brain through the optic nerve to make you see.
It all happens so instantaneously and precisely! The retina is large, covering the entire back of the eye, but only one very specialized area of the retina, called the macula, gives us the 20/20 vision that we are used to.

OPTIC NERVE
The optic nerve is the main nerve of the eye. It is like a coaxial cable that is carrying approximately a million nerve fibers from the retina to the part of the brain that “sees”, called the optical cortex.
People sometimes wonder if the eye can be “transplanted”. First we would have to figure out how to match up a million microscopic nerve fibers and get them to the right place! There are diseases that can cause problems in the optic nerve. It can have strokes, like the brain that it is a part of. There can also be inflammation or infection of the nerve that can disrupt vision.
MACULA
With a name like macular degeneration, you know this part of the eye is key to understanding this disease. The macula is the part of the retina that the light is focused on. We have been discussing the importance of focusing light on the retina and the macula is where the action is.
The “cones” of the retina are concentrated in the macula and give the clearest and the best color vision. The remainder of the retina, the so called retinal periphery, has a greater proportion of “rods” and less distinct and less colorful vision, though we use it importantly at night.
In dry AMD the macula develops scars that are called “drusen”. They appear as little white spots under the retina. There can also be macular scarring (“pigment”) and macular atrophy (loss of tissue). Now you can see why AMD can cause decreased or distorted vision. There is an abnormal process occurring in the macula, that is so critical to good sight.

Eye Anatomy

Learn the main anatomical parts of the eye and how the eye works.

Everything Eye

At EyeDefense Vitamins we are not only dedicated to providing you with products sourced from the finest quality ingredients. We also provide you with the latest updates and scientific breakthroughs concerning eyes.

PUPIL

The pupil looks like a black hole in the middle of your eye, but actually it is the lens of the eye that you are seeing.

The pupil is more than just a round hole in the iris! It is an important part of the eye.

We are used to thinking of a cell phone as a camera and so we can miss the importance of the “aperture” that is used to focus in a traditional camera. The pupil works as that aperture in the “camera” that is your eye!

CORNEA

The cornea is the clear part of the eye that acts as a protective cover. It protects the iris (the colored part of the eye), the pupil and the lens. Compare the cornea to the "clear crystal" of a watch protecting the hands of the watch.

But the cornea is more than just protection!

It has 5 layers and is very complex in its architecture. It is has a key refractive function: it helps focus light on the retina.

The cornea must stay wet on the surface so that it is smooth (that is why we blink) and it must remain “dry” on the inside so that it can remain clear.

The cornea can become scratched (corneal abrasion), infected (corneal ulcer) or dry.

IRIS

The iris controls the size the pupil. As we have discussed above, the size the pupil allows the eye to focus the image on the retina in the back of the eye.

LENS

You can see the lens of the eye when you look into someone’s pupil, but only a small part of the entire structure is visible. The lens is like the lens of camera, it changes shape to focus light.

The lens also affects every person over the age of 40! As the lens ages it no longer changes shape as quickly or easily. Focusing on near objects, when reading a book for example, becomes more difficult. This is why reading glasses are needed as the lens ages.

The lens is famous because of cataracts. When you get older the lens, which is naturally clear, begins to take on a yellow tinge that is called a cataract. When the cataract is yellow enough the person becomes aware of it because images will no longer clearly focus.

CILIARY BODY

If the eye is not draining its fluid normally the pressure can build up inside the eye. This is called glaucoma. Many glaucoma drops work by suppressing the function of the ciliary body in its fluid making capacity.

The ciliary body is also the origin of the so called “zonules” that move the lens and allow it to change shape and thereby focusing the light on the retina.

CHOROID

The choroid is the other blood supply. It is under the retina, serving the inner retina, and because its vessels are not seen on a photograph, it is harder to understand its great importance. It is critical to the very metabolically active inner retina that is processing light constantly as we see.

We will talk about wet and dry macular degeneration in another section, but it is from this choroid that abnormal blood vessels spring and when they leak or break, they cause wet AMD.

RETINA

It all happens so instantaneously and precisely! The retina is large, covering the entire back of the eye, but only one very specialized area of the retina, called the macula, gives us the 20/20 vision that we are used to.

OPTIC NERVE

The optic nerve is the main nerve of the eye. It is like a coaxial cable that is carrying approximately a million nerve fibers from the retina to the part of the brain that “sees”, called the optical cortex.

MACULA

With a name like macular degeneration, you know this part of the eye is key to understanding this disease. The macula is the part of the retina that the light is focused on. We have been discussing the importance of focusing light on the retina and the macula is where the action is.

The “cones” of the retina are concentrated in the macula and give the clearest and the best color vision. The remainder of the retina, the so called retinal periphery, has a greater proportion of “rods” and less distinct and less colorful vision, though we use it importantly at night.