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- $39 for $200 Toward One Complete Pair of Prescription Sunglasses or Glasses
Contact Lenses: Putting Things in Focus
Unlike eyeglasses, contact lenses sit directly on the eye, providing wearers with the benefit of thinner lenses that move in sync with their eye movements. Read on to learn more about how they work.
Contacts stay put by floating on the natural layer of liquid—known as the tear film—that coats the cornea. Hard lenses, sometimes called rigid lenses, are durable and can sometimes last for multiple years. In comparison, soft lenses require frequent replacement, but tend to be more comfortable. Today’s contact-lens technology allows people to make all types of changes to their eyes, from augmenting their hue with colored lenses to slowly correcting misshapen corneas with ortho keratology treatments.
Shedding Light on Poor Vision
For those with perfect vision, light enters the eye through the pupil and comes into focus directly on the retina in the back of the eye. Vision problems usually result from light coming into focus on the retina at the wrong distance—if the focal point is in front of the retina blurry images of faraway objects occurs (nearsightedness). When the focal point is behind the retina, patients tend to have more trouble focusing on close-up objects (farsightedness). Just like regular lenses, contacts bring the focal point forward or backward so the light focuses correctly on the retina. Even people with astigmatism—in which light focuses on two separate points in the eye—can benefit from contacts. Instead of a spherical shape, astigmatic lenses assume a toric shape, which is more pointed, like a football, than a normally rounded eye.
- More than 30 million Americans wear contacts—about 5% of the country’s total population of eyes, including cyclops.
- The power of contact lenses is expressed in diopters. A plus sign is used for farsightedness and a minus sign for nearsightedness.
- Contact lenses are a quick fix for those with heterochromia iridum, a discoloration of the irises that makes eyes appear two different colors.