Eye vision enables us to see clearly the objects in our surroundings at different distances and under numerous conditions of lights.
How Eye sees?
Eye works by changing the curvature of the lens to bring the image to a focus from any light from a single point of a distant object and/or a near object called as eyesight or eye vision.
The eyes are the windows to the world; it allows us to see objects both far and near.
Light reflects off an object enters the eye. The light enters the eye through the front window of the eye, called the cornea. A clear covering helps to focus the light. Other sides of the cornea are clearer, watery fluid is the aqueous humor.
After light passes through the aqueous humor, it passes through the pupil, the central circular opening in the colored part of the eye called the iris. Depending on the amount of light available, the iris can contract or dilate, limiting or increasing the amount of light needed that gets deeper into the eye. The light then goes through the lens, which focuses the light (Just like the lens of a camera). The suspended lens changes shape with the help of ciliary muscle to focus on light reflecting from near or distant objects. Lens focuses the light on the retina at the back of the eye.
The retina is a thin layer of tissue at the back of the eye that contains millions of tiny light sensing nerve cells called rods and cones, which are naming for their distinct shapes. Cones are concentrated in the center of the retina; an area called the macula. In bright light conditions, cones provide clear, sharp central vision and detect colors and fine-details. Rods are located outside the macula and extend all the way to the outer edge of the retina. They provide peripheral or side vision. Rods also allow the eyes to detect motion and help us see in dim light and at night. These cells in the retina convert the light into electrical impulses. The optic nerve sends these impulses to the brain where it produces an image.
Visual information as impulses from the retina is transfers from the eye to the brain via the optic nerve. Because both eyes seeing from slightly different position and got different images, the brain has the ability to mix properly these two images in such a way to receive a complete clear actual picture.
Sometimes eyeball shape makes it difficult for the cornea, lens, and retina to work properly as a team. When this happens, the person eye sees will be out of focus. In addition, they need to wear eyeglasses to focus images correctly on to the retina and allow them to see clearly.