How does the eye work
The human eye functions in a manner that is very similar to a camera: The external cornea behaves just like a lens cover while the iris and pupil act like the aperture of the camera, and the eye lens has a role in focusing light similarly to the camera's lens. Let's get a closer look at the structure of the eye to learn more about the eye's normal functions
A white protective layer called Sclera covers most of the eyeball. The frontal part of the sclera which covers the front area of the eyeball where the colored part of the eye is located is called Cornea. Unlike the Sclera, the Cornea is totally transparent and allows complete entry of light.
Behind the Cornea lays the iris (the colored disk) and the pupil (The small black disk). The role of the pupil is to control the quantity of light that enters the eye. It is attached to tiny muscles that contract upon exposure to strong light to reduce the opening while they dilate in darkness to allow more light to enter the eye.
Once controlled light enters through the pupil it is focused through the colorless lens of the eye called Crystalline. The Crystalline is suspended in the eye by thin fibers known as ciliary muscles. These fibers control the shape of the lens: when you're looking at a close object the lens becomes thicker and when you look away at something more distant it becomes thinner. The resulting image is finally received by the Retina which is located at the back of the eye. The Retina is lined with photoreceptor sensory cells which convert the image received into signals that are transmitted into the brain via the optic nerve and it's when the brain receives these impulses that you can actually perceive what your eyes have been receiving.
Now that you understand how the normal eye works, you will understand better what causes you not to see clearly.