How the Eye Works

Normal Vision
Called "emmetropia", persons with normal eyesight enjoy seeing clearly are all distances without corrective lenses. Driving, computer monitors and books are all in clear focus.

If light rays are not directed to a focus on the retina, eyesight is compromised depending on the type of mis-focus.

Nearsighted
Persons that are nearsighted (or myopic) see objects held close up more clearly than those in the distance.  In this condition, the eye's focus is too strong (in front of the retina) and distance objects are blurry.  A nearsighted person also will be affected by presbyopia, however without the nearsighted correction (glasses or contact lenses) in place, the presbyopia may not be noticed.

Farsighted
Farsighted, or hyperopic, persons see objects in the distance clearer than those held close.  In this condition the eye's focus is too weak (behind the retina) and near vision is especially blurred. A farsighted person also will be affected by presbyopia and typically will have exaggerated presbyopic symptoms.

Astigmatism
An eye with astigmatism sees objects blurry at all distances primarily due to the front of the eye not being round enough.  This curvature does not allow light to focus accurately while looking at objects at any distance. Astigmatism can occur with nearsighted or farsighted eyes, whether you are in a presbyopia age range or not.

Other Physical Causes to Poor Vision
Your eye doctor routinely checks your vision for common refractive disorders and for a multitude of other conditions, which may affect clearness of vision.  Conditions such as glaucoma, cataracts, macular degeneration, and diabetes are examples of general changes to the eye and general health that can also affect vision.  It is important to have your eyes examined periodically to assess and maintain good eye health and vision.