The human eye is a marvel of built-in engineering, combining reflected light, lens imaging capability, multiple lighting adjustments and information processing – all in the space of your eyeball. When working properly, the human eye converts light into impulses that are conveyed to the brain and interpreted as images.
To understand how the human eye works, first imagine a photographic camera – since cameras were developed very much with the human eye in mind.
How do we see what we see?
Light reflects off of objects and enters the eyeball through a transparent layer of tissue at the front of the eye called the cornea. The cornea accepts widely divergent light rays and bends them through the pupil – the dark opening in the center of the colored portion of the eye.
The pupil appears to expand or contract automatically based on the intensity of the light entering the eye. In truth, this action is controlled by the iris – a ring of muscles within the colored portion of the eye that adjusts the pupil opening based on the intensity of light. (So when a pupil appears to expand or contract, it is actually the iris doing its job.)
The adjusted light passes through the lens of the eye. Located behind the pupil, the lens automatically adjusts the path of the light and brings it into sharp focus onto the receiving area at back of the eye – the retina.
An amazing membrane full of photoreceptors (a.k.a. the “rods and cones”), the retina converts the light rays into electrical impulses. These then travel through the optic nerve at the back of the eye to the brain, where an image is finally perceived.
A delicate system, subject to flaws.
It’s easy to see that a slight alteration in any aspect of how the human eye works – the shape of the eyeball, the cornea’s health, lens shape and curvature, retina problems – can cause the eye to produce fuzzy or blurred vision. That is why many people need vision correction. Eyeglasses and contact lenses help the light focus images correctly on the retina and allow people to see clearly.
In effect, a lens is put in front of the eye to make up for any deficiencies in the complex vision process.
The main parts of the human eye include:
Special thanks to the EyeGlass Guide, for informational material that aided in the creation of this website. Visit the EyeGlass Guide today!