Learn About The Eye

The Eye is one of the most important structures of the human body, it filters the light that enters the eye ensuring that we see the world in great detail and color.  It is a sensory organ of the visual system.  An optometrist can observe a lot about a person’s health by having a noninvasive look at the nerve, blood vessels, retina and other structures of the eye.

The eye which is 1 inch in diameter sits in the orbit which is part of the skull.  Interestingly only 1/6 th of the eye is visible.  The eye is protected by the eyelids, eyelashes and eyebrows ensuring that nothing harmful enters the eye.

 

PARTS OF THE EYE:

The Cornea:

The cornea is the outermost covering of the eye and is shaped like a sphere.  The cornea is composed of serval layers ensuring the inner parts of the eye stay protected.  In addition to protecting the eye, the cornea also helps focus the light that we see.

The Pupil:

The pupil appears at the center of the eye.  It allows light to enter the eye so that the eye can focus on objects ahead.

The Iris:

This is the part of the eye that contains the pigment which gives the eye its color.  It also contains muscle fibers that allow the pupil to dilate in dark light and constrict in bright light.

The Lens:

The lens is located directly behind the pupil and focuses the light the pupil brings in.  Muscles on either sides of the lens allow the lens to change shape to control the amount of light that the lens focuses.

The Retina:

The retina is located at the back of the eye and is where the light is focused by the lens.  The retina contains the optic nerve which transmits the images that the eye sees to the brain for the brain to interpret.  At the back of the retina is the macula which is also referred to as the central vision.  This is where the all the details of the images are interpreted.

Nearsightedness or Myopia:

Nearsightedness or myopia is a visual condition where near objects are seen clearly, but distant objects do not come into proper focus.  This can usually occur if the eyeball is too long or the cornea has too much curvature to it so that light entering the eye does not properly focus onto the retina.  This is a very common condition which normally starts in childhood and can increase until the mid to late 20’s.  This condition can be inherited from our parents, aunts, uncles, grandparents.  Glasses and/or contact lenses can help to treat this condition and allow the patient to see clearly at distance.

Farsightedness or Hyperopia:

Farsightedness or hyperopia is a visual condition where distant objects are easier to see than near objects.  This can occur because the eyeball is too short or the cornea has too little curvature to it so that near objects are not properly focused onto that retina.  This condition can cause more strain and effort to see and read things at a close range.  This can result in fatigue, tension, discomfort and headaches.  This condition can be inherited or a result of environmental factors.  Glasses and/or contact lenses can help to treat this condition and allow the patient to focus with clear and comfortable vision at near.

Astigmatism:

Astigmatism is a refractive error (part of the prescription) that occurs when the cornea or the lens in the eye is an irregular shape like oval or cylinder.  This irregular shape can prevent light from focusing properly onto the retina causing images to be distorted and blurry.  Astigmatism can occur in varying degrees and can occur alongside myopia and hyperopia.  Uncorrected astigmatism can cause distorted vision, headaches and eye strain.  This condition can be inherited and can be caused by small differences in the growth and alignment of the eye. Glasses and/or contact lenses can treat this condition so that the patient can focus at objects near and far clearly.

Presbyopia:

Presbyopia is a normal change that occurs in the lens of the eye when it loses its elasticity and flexibility.  This change occurs with age and results in difficulty to focus objects at a close range.  This condition usually starts after the age of 40 years old and progressively gets worse until approximately 60 years old.  Early in the condition fine print at a close range will be sometimes difficult to focus and later progresses to all objects at a close range and arms lengths are difficult to focus.  The symptoms of this condition are blurry vision when reading, difficulty focusing at close objects in dim lighting, headaches and eye strain and the need to hold reading material at arm’s length.  Glasses and multifocal contact lenses can treat this condition and allow the patient to work at near and computer tasks comfortably.

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