The human eyes
Eyes are one of the most important organs of the body. A healthy pair of eyes means a clear vision, which plays a major role in day-to-day life and quality of experiences.
Humans have binocular vision, meaning that both the eyes create a single combined image. Optical components create an image, which further gets perceived and interpreted by the brain via connecting neurons. The entire machinery works in quite an intricate manner.
Structural Components of the Eye
This biological camera is made up of:
Eyelids are the outermost protective parts of the eye. They act as ‘shutters’ and primary barriers against external environment. Boundaries of eyelids are covered by tiny hairline termed as eyelashes.
As we go past eyelids, the next component is the circular frontage of the spherical eyeball, termed as cornea. Cornea is the first optical component of the eye machinery, dealing first-hand with the incoming light. Its function is of a primary filter, before passing on the light to the lens and retina.
The central portion of the front of the eyeball is termed as iris. Iris is a pigmented structure. Eye color (black, brown, blue etc.) is defined by the pigmentation of iris. The central aperture of iris is called pupil.
It is circular in shape, and allows light to pass through onto the lens. Just like the aperture of a camera, it controls the amount of light that goes in. In bright environments, the pupil of the eye constricts, while in dark environments, it dilates.
The process of dilatation and constriction of pupil is not instantaneous. This is the reason we can’t see anything for few moments when we enter from bright sunlight to a dark interior, and also the reason we can’t keep our eyes wide open when we suddenly switch on the lights in the middle of the night.