How It Works: Eyeglasses and Contact Lenses
Eyeglasses and Contact Lenses: Eyewear has gone from being merely functional to fashionable. Nearly 64 percent of American adults wear eyeglasses and 34 million wear contact lenses, says The Vision Council, a global organization dedicated to manufacturers, distributors, and consumers with information pertaining to eye-related services and products. About 12 million Americans have uncorrected vision problems. Many don’t realize that health conditions not directly related to the eyes, like diabetes and high blood pressure, don’t always have flagrant warning signs. One in four kids cannot see well enough to realize their learning potential in school. Some wear colored contacts or eyeglasses simply because they want to, not because they need to.
How the Eye Works
Eye anatomy is made up of 10 major parts:
- iris |
- cornea |
- pupil |
- sclera |
- lens |
- optic nerve |
- macula |
- fovea |
- retina |
- vitreous gel
When you look someone straight in the eye, you notice the iris, the pupil and the white space. The iris is your eye color and it regulates how much light gets through your eye. Your pupil is black and sits in the center of your iris. It is the iris that controls the size of your pupil, not the pupil adjusting to the light. The more light that shines in your eyes, the smaller your iris makes your pupil. The less light, your iris pulls back, enlarging your pupil. The opaque, white of your eye is called the sclera. The sclera uses six tiny muscles to control eye movement. Those are the parts you can see just by looking at someone. Your retina, the most important part of your eye, you cannot see. Your eye doctor looks at your retina when he examines your eyes. It looks like a big orange ball with veins in it. If objects don’t focus correctly on the retina, then you might need eyeglasses or contacts.
Why We Need Corrective Eyewear
Most people wear glasses because they are either farsighted or nearsighted. Farsighted means that you can see images farther away but not up close. Nearsighted means the opposite: you can see close up, but images farther away are blurry, unfocused. This happens because what you are seeing—the images—are not projecting on your retina in the correct spot. Nearsighted people have images focusing in front of the retina. Farsighted people have images focusing behind it. There are other conditions that prompt the need for corrective eyewear and contacts, but these are the most common. Here are some of the warning signs that you might need vision correction:
Adult Warning Signs
- Double vision
- Difficulty reading
- Difficulty seeing close or far away
- Not seeing colors the same as you used to
- Bright lights impair your night vision
- Glare and halos around light
- White spots on your pupils
- Limited or no peripheral vision
Warning Signs in Children
- The presence of neurofibromatosis, diabetes, HIV, sickle cell anemia and other seemingly non-related conditions and diseases
- Squinting
- Holding books very close to eyes
- Rubbing eyes all the time, red eyes or teary eyes
- Crossed eyes
- Kids born too early often have eye problems (prematurity)
- Kids whose development has been delayed
- Family history
How Glasses and Contacts Work
Glasses and contacts are uniquely designed and refined to meet the needs of your eyes. Your eye doctor works up a ratio or a fraction that tells those making the glasses what kind of vision you have and what kind of lenses you need. They also will use measurements to help images focus on the correct spot on your retina. Your lenses will bend and focus light at precise angles in order for those images to target the center of your retina. Both glasses and contacts correct vision in essentially the same way. Glasses are worn over your eyes and are anchored by your nose and ears, while contacts are fitted to the dimensions of your eye itself. Those who alternate wearing eyeglasses and contacts usually feel that contacts give better depth perception and lets them see better side to side.
