Optic Nerve = transmits information from the eye to the brain

Macula = Central area of the retina

Fovea = Center of the macula.  All the optics of the eye focus on the fovea.  It does our central, fine detailed vision and color perception.

Retina = Layer of photoreceptive cells lining the interior back of the eye

Vitreous Gel = Fluid that fills the posterior segment of the eye

Iris = Colored part of the eye

Pupil = Opening in the iris.  Changes size with changing light conditions

Cornea = Clear front section of the eye


Optics of the Eye

  • If the optics of the eye are perfect, the image that enters the eye is focused right at the plane of the  retina

Myopia = Near Sighted

  • Image is focused in front of the retina, need minus (-) power lenses to correct
  • The eye is not able to focus (accomodate) to overcome this, distance is blurry

Hyperopia = Far Sighted

  • Image is focused behind the retina, need plus (+) powered lenses to correct
  • Can use our eyes focusing ability (accomodation) to overcome low amounts of hyperopia to make vision clear.
  • But this can put uncomfortable strain on your eyes, especially at near.
  • May not be able to overcome moderate or high amounts of hyperopia
  • As we lose our ability to focus with age (Presbyopia), will lose the ability to focus through the hyperopia.


  • Image is distorted more in one axis than the other
  • Usually caused by a distortion in the cornea (front clear part of the eye)
    • Curvature of the cornea is different in the vertical axis than the horizontal axis
  • Visually, the image would be blurred more in one direction
  • This gives two different powers needed in the prescription to correct this distortion


  • Natural aging change occurs in the lens of the eye making it less flexible
  • A decrease in this flexibility corresponds to a decrease in our ability to focus our eye for near tasks
  • Normally begins affecting people in early 40's


  • Glaucoma
    • Damage occurs to the optic nerve
    • Primary risk factor is high eye pressure
    • Painless loss of peripheral vision
    • Estimated half of the people with glaucoma do not know they have it
  • Cataracts
    • When the lens inside the eye becomes cloudy
    • UV exposure can increase the rate of opacification
  • Macular Degeneration
    • Damage to the central part of the retina
    • Can result in loss of central vision
  • Dry Eye
    • Common condition causing pain, burning, red eyes
    • Many different factors can cause or exacerbate symptoms
    • Variety of treatments are available
  • Allergies
    • Seasonal and environmental allergies often cause itchy and watery eyes
    • Treatments are available to help relieve these symptoms

Common Medical Conditions That Can Effect Our Eyes

  • Diabetes
    • Can affect many parts of the eye
    • Changes in vision, cataracts, glaucoma, delayed healing, retinal hemorrhages are a few of the problems that can be detected with an eye exam.
  • Thyroid Disease
    • Hyper or Hypo thyroid disease can cause many changes and problems with the eyes.
  • Hypertension
    • The eye is the only place in your body you can view blood vessels with no skin over top.  An eye exam can give clues as to the condition of blood vessels throughout our bodies.

    External links to more information