How do Eyes Function?

The ability of the human eye to produce vision is an incredibly complex chain of events, justifying the need to take good care of their health. It begins when external light rays are focused to the visual processing area of the eye, called the retina. This process is dependent on various anatomical structures of the eye, operating together to accurately capture the intricate images of the world.

Firstly, light passes through the normally transparent cornea. Then, the two muscles that control the iris, making the pupil appear smaller and larger, allow light into the eye. The ciliary body is the muscle that controls the shape of the lens which focuses the light rays to the retina, where the brain can then begin to process the information. The retina contains rod and cone shaped photoreceptors, which capture the energy of the light rays and consequently transmit electrical signals to the brain.

Rhodopsin is the chemical within the photoreceptors of the retina that traps the light for processing. Unfortunately rhodopsin is quite sensitive and is lost after continuing exposure to light. Consequently, it has to be replenished. Vitamin A is necessary to form retinal, which is part of the rhodopsin molecule.

Important to the capturing and harnessing of the light wavelengths allowing for visual acuity or sharpness, is the macula area which is the central part of the retina. The health of the macula, containing a large proportion of photoreceptors, is imperative in maintaining the substantial portion of the visual field. If this area is damaged or deteriorated, a substantial loss of vision will occur in the central field of view represented by a large obstructive black spot. Many lifestyle conditions can influence the health and integrity of the macula, so any activity that may reduce any harmful effects and or promotes the health of the eye is ideal. If all of these structures are working in good health, images are transmitted to the brain via the optic nerve for higher perception and interpretation.

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The Structure of the Human Eye (www.lighthouse.org)