The Eye: How We See?
“How we see?” is a question that is hard to answer without using too much medical terms because vision process of a human is very complicated. Let’s try to understand the main principle of it without going too deep into details.
Human eye is a complex optic system consisting of several lenses and a special sensor perceiving the image.
How do our eyes see? Here’s how:
1. Light rays get to the pupil that is located behind the eye cornea. Cornea is the first lens of the system.
Pupil is located in the center of iris and can narrow or widen regulating the intensity of the light flux coming inside the eye.
2. Light rays that passed through the pupil are refracted by crystalline lens (also called “lens”) – the second lens of the eye.
Crystalline lens can change its form with the help of the special muscle. To view close objects muscle toughens and lens becomes more convex, to view far objects muscle relaxes and lens becomes flat. This process is called accommodation.
3. After passing through the lens refracted rays get to the retina – distinctive concave screen.
Retina’s outer cell layer consists of 2 types of specific cells: rods and cones. Light rays by getting to the retina irritate these cells, as a result of it the nerve impulse is formed.
4. Nerve impulse with the help of the optic nerve transports the information about the image to the brain where it is finally being interpreted.
These are the basics of how our eyes see. For more information about human vision process, please, check special medical literature or trusted medical internet resources.