vision problems:
understanding your eyes

You turned to eyeglasses and contact lenses when life became blurry. When you visited your eye doctor, you probably heard about vision problems like nearsightedness, farsightedness, and astigmatism, but all that mattered was that you could see better when you left. So how do your eyes work, and what happens to your eyes when your vision becomes blurry?

How Your Eyes Work How Vision Problems Happen

Your eye works much like a camera. The light and images you see pass through the cornea and the lens at the front of your eye. They focus directly onto the retina, the nerve layer at the back of the eye, which then sends the image to the brain through the optic nerve.

Light rays must be bent, or refracted, by the cornea and the lens so they can focus on the retina. If you have a refractive error, the shape of your eye doesn't bend the light properly, giving you vision problems.

With the normal eye, the images you see focus directly onto the retina, at the back of the eye.

Common Vision Problems

Your doctor can identify many of the common vision problems, including:

• Nearsightedness images focus in front of the retina because the eye is too long or the cornea too curved, so objects far away are blurry.
• Farsightedness -- images focus behind the retina because the eye is too short or the cornea is too flat, so objects close to you are blurry.
• Astigmatism images are distorted and are not uniform in all directions, so objects both near and far appear blurry.
• Presbyopia disorder caused by the normal aging process that typically affects reading vision.

Doctors can also measure the severity of these vision problems by evaluating the shape of your eye and its cornea. The results determine your prescription.

These problems are usually corrected with eyeglasses, contact lenses, or by laser vision correction procedures. However, good visual acuity does not necessarily mean good visual quality. Experts believe other qualitative factors contribute to common low-light vision problems, including glare and halos. You can have these vision problems and still score 20/20 on a vision exam.