Each eye forms it own image, and it is the brain's job to fuse the two images into one. For the brain to do its work, the eyes must be aligned, move together and produce images of similar size and shape. When the eyes are not coordinated, they have to work hard to see clearly, often causing eyestrain or headaches.

Good vision is all about curves. A correctly shaped cornea and lens direct the light to the right spot on the retina to produce a clear, sharp image. When the curvature is too flat, too steep or inconsistent, the image does not fall precisely on the retina, and curved lens (or possibly LASIK surgery) are used to correct myopia (nearsightedness), hyperopia (farsightedness), astigmatism (distorted vision) and/or presbyopia (difficulty adjusting to close distances when one becomes 40 or older).

To your eye doctor, your eyes are window to your overall health. Many illnesses show their earliest signs in the eyes, and many diseases can affect your vision. During your eye examination, your Today's Vision doctor will look for signs of:

Hypertension: The appearance of irregular blood vessels on the retina can indicate high blood pressure.

Diabetes: Small, circular areas of bleeding on the retina may be an early sign of diabetes. Increases and decreases in blood sugar level can cause blurred vision and retinal changes.

Headaches: These may be caused by or worsened by vision problems such as eye strain.

Stroke: The vessels in the eye may point to a risk of stroke.

High Cholesterol: Hypertension and high cholesterol levels are often linked. The condition of the veins and arteries in the eyes can be a warning.

Multiple Sclerosis: Double vision, visual field loss and uncoordinated or involuntary eye movements may be an early sign of MS.

The eye is susceptible to its own diseases, many of which have minimal symptoms associated with them. Your Today's Vision doctor routinely tests and looks for signs and symptoms of many eye diseases, including:

Glaucoma: High levels of pressure inside the eye due to failure of the eye to regulate its own internal pressure. Early detection is crucial to prevent loss of sight.

Cataracts: The internal lens of the eye becomes cloudy and must be removed and replaced with a synthetic lens implant.

Take a few minutes to learn more About the Eye, Eye Exams, Disorders and Treatments. You only have one set of eyes - and your good health.