The normal healthy eye is almost spherical and is made up of three layers:
1. The Outer Layer (Sclera)
2. The Middle Layer (Choroid)
3. The Inner Layer (Retina)
The Sclera is opalescent, which means it has “a milky iridescence like that of an opal”!! Its center is transparent and is called the Cornea. Light comes through the cornea.
Behind the cornea, the second layer, or Choroid is visible. The Choroid Layer contains tiny blood vessels which transport blood to and from the eyes. When we do our exercises, one of our aims is to increase this blood flow, to get more oxygen and nutrition to the eyes, and also to remove waste products.
The Choroid layer contains the Iris (the part of the eye that is colored), with the Pupil in its center.
The Iris is like a circular muscle that expands and contracts to adjust the size of the pupil. This lets more or less light into the eye, and helps us to see perfectly, whatever the lighting conditions (or at least it does in a healthy eye).
The pupil, in the normal eye, gets smaller when looking at a distant object, and larger when looking at something close by.
Interestingly enough, the pupil also changes size according to the emotions. When you look at someone you love very deeply, or something that gives you great pleasure, the pupils get larger.
When you look at something you don’t like at all, they get smaller!
So now you have a way to know ‘who loves ya baby’!
Right behind the Iris is the Crystalline Lens, which receives the light as it passes through the Pupil and focuses it upon the Retina, just like you did as a child when you used a magnifying glass to focus the sun onto a piece of paper.
Connected to the Crystalline Lens by a tiny ligament, is the Ciliary Muscle, which controls the contraction and expansion of the Crystalline Lens. In other words, the Ciliary Muscle changes the shape of the eye’s lens and therefore changes your focus.
The third, Inner Layer, or Retina, is a continuation of the Optic Nerve, which is located at the back of the eye. Actually, it’s a direct outgrowth of the brain!
The Retina receives the light that is focused upon it by the lens and then sends signals to the brain. The brain interprets the signals and you ‘see’ the image of the outside world! Neat huh!
