Vision

What is vision?

Vision is defined as being the ability to see. Yet few people know exactly what goes on in the eye.

  1. Light passes through and is focused by the cornea.
  2. The iris adjusts the size of the pupil accordingly.
  3. The light passes through the pupil and into the back of the eye
  4. The light is focused even more by the crystalline lens, behind the pupil.
  5. The light reaches the retina, which contains photoreceptor cells (rods, cones, and photosensitive ganglion cells), that convert the light into electrical impulses, which get transmitted to the brain to produce an image.

Anatomy of eye

Pupil – A hole that lets in light to the back of the eye

Cornea – The clear front surface of the eye that is responsible for about 2/3 of the eye’s refracting power.

Iris – A circular area towards the front of the eye that adjusts the size of the pupil. The iris is also responsible for eye color.

Retina – A layer in the back of the eye that contains light-sensitive tissue, called photoreceptor cells. The cells responsible for vision are called rods and cones. Rods mainly function in the dark and see in black and white. Cones are the main source of color in our sight.

Macula – A pigment-filled section near the center of the retina. The macula consists of three types of pigment: Lutein, Zeaxanthin, and Meso-Zeazanthein. Because the macula is yellow, it absorbs excess blue and ultraviolet light, but overtime can break down- leading to diseases such as Age-Related Macular Degeneration (AMD).

More coming soon…