Interesting Facts about Eye - Functions and Conditions
Know your Body

The Eye

Authored by DesiMD Doctor on 18 Mar 2013 - 11:58


The eye can be considered virtually the most complex organ in the human body (not including the brain) that allows us to view the beauty of the world. In many ways, the eye is comparable to a pin hole camera, being able to cause refraction of light and producing an image so that we may see.
The eye is opaque in nature and saturated with a liquid called humor.

  • Cornea: To the front of the eye (anterior) is located a transparent body known as the cornea which helps to protect the eye from foreign contaminants. In addition to this important function, however, it is the cornea which also causes the refraction of light as it goes through the eye.
  • Pupil:The pupil is also known as the black of the eye, and is in effect a vacuum, in that it allows light to enter, but that light later becomes absorbed by other surfaces and will not leave through the pupil. Hence, the black appearance since black is a color produced when no light hits an object.
  • Iris: The relative size of the pupil is controlled by the iris, which is the colored portion of the eye. The iris may range in colour from being green, brown, amber, blue and a variety of intermediate colours that add to unique traits of that person. In intense lighting scenarios, the iris causes the pupil to shrink helping to reduce light that enters the eye. The opposite is true in dim light; it opens the pupil to facilitate proper vision in dark environments.
  • Lens: Once light enters the eye, it passes through a structure called the crystalline lens, which is the most important refractive structure to help form an image.
  • Retina:The retina, as mentioned before absorbs much of the passed light and with the help of rods and cones, specialized cells, determine color and sharpness of an image. This information is finally relayed to the optic nerve and then the brain.

Functions of the Eye:
The function of the eye can be summed us as basically helping in formation of an image via relay impulses to the brain.  In addition, however, the eyes aid in formation of coloured images thanks to the presence of special cells on the retina called cones. These cones are also responsible for aiding vision during the night.

Conditions which may affect the Eye:

There are a range of conditions that may affect the eyes, some being only self limiting, while others require immediate medical attention.
Following is a list of common eye conditions:

  • Glaucoma- one of the most common vision stealers, via damage to the optic nerve. This damage is in large part due to an elevated intraocular pressure, or IOP
  • Cataracts- this is a condition that occur when the tiny lens on the eye become occluded with a big cloudy mass that continues to spread. The result is no light enters the eye and vision is lost. Most persons who live to an advanced age will probably develop cataracts
  • Conjunctivitis- commonly known as red eye or pink eye, the most common cause of conjunctivitis is bacterial in origin. This results in inflammation of the conjunctiva, and the infection is highly contagious. Conjunctivitis may also be caused by viruses, allergies or external influences although bacterial conjunctivitis is most common
  • Allergies- these are some of the most common eye conditions, accounting for a large percent of visits to an ophthalmologist. It frequently occurs in people who suffer from hay fever or dermatitis, but is also caused by use of certain medications or cosmetic products
  • Styl stye- a stye is a swollen, painful, red bump that appears on the eyelid or at the base of an eyelash.  They are believed to be due to clogging of the glands that make oil on the eyelid. They will appear yellow a short while after, as pus develops and accumulates
  • Keratoconus- this is a condition that occurs when inappropriate pressure exists in the cornea, leading to a distortion of the lens (in a bulging manner). Hard contact lens may be needed to restrict the distortion, as vision difficulties normally result
  • Blepharitis- this is a condition resulting in inflammation of the eyelid, either on the outside or the inside. It often results in excessive scratching, watering of the eyes and severe crusting on the eyelids upon waking
  • Strabismus- commonly known as crossed eyes, this is caused by a defect in one eye during development, it having a lateral or vertical tilt
  • Nearsightedness
  • Farsightedness
  • Color blindness ( nearly solely occurring in men)

Eye Care Statistics:

  • Worldwide, more than 800 million people are blind or severely visually impaired
  • More than 80% of vision loss cases could be avoided
  • Women have an inherently higher risk of developing vision issues, the current ratio of women to men being 66:33
  • Cataracts are the leading cause of blindness in the world
  • Nearsightedness is the leading source of vision difficulties that can be corrected
  • Loss of working income due to eye issues costs about $270 billion annually

Interesting Facts about the Eye:

  • Your eyes will blink more than 27000 times daily
  • An adult eye weighs about one ounce
  • The human eye is capable of detecting candlelight at a distance of over 14 miles away( under the right conditions)
  • The cornea is the only part of the body which is not perfused with blood vessels
  • All babies are born color blind
  • Your nose starts to run when  you cry since tears pass through the lacrimal duct( connecting the eye to the nose)
  • You cannot sneeze with your eyes openAround 50% of your brain is involved in processing visual stimuli