The Vision Council of America estimates that in 2010, there are 174 million corrective lens wearers in the United States. Whether the choice is eyeglasses or contact lenses, the basic process is the same. These lenses bend rays of light so that they come to a clear focus on the retina. There are also several notable differences in how these lenses function, and understanding these differences can help you choose wisely.
Consistent Correction
Eyeglass lenses, being a solid chunk of plastic, bend light rays in the exact same way every minute of every day. Therefore, your vision correction is consistent and dependable. Contact lenses, by contrast, are paper thin and as bendable as a piece of cellophane. The natural flexing of contacts and their interaction with the eyes' tear film can cause small variations in vision throughout the day. If you are adverse to the occasional "blurry moment" then contacts may not be your best bet.
Image Clarity and Distortion
Both eyeglasses and contacts deliver a crisp, clear image as you look straight ahead. With eyeglasses, however, as your eye moves out towards the periphery of the lens, you encounter more and more "prismatic" distortion. The stronger the prescription is, the more distortion occurs. Theoretically, the same is true with contact lenses, but due to the thinness of the material and the fact that contacts move with your eye, the distortion is greatly reduced. That is one reason why people with high prescriptions tend to prefer contacts.
Peripheral Vision
Sitting away from your face, eyeglasses have a built-in problem with peripheral vision. To see well to the right side, you must turn your head to the right. If you just glance sideways you'll encounter blur as you go outside of the glasses' field of vision. Contacts, moving with your eyes, deliver far greater peripheral vision. This is a key point for sports enthusiasts.
Comfort
Contact lenses work in tandem with your eyes' tear layer, so any change in your tears can impact lens comfort. Allergies, air conditioning, wind, and many other factors can make your eyes a little more or less watery, and that can greatly affect contact lens comfort and performance. Eyeglasses free you of these concerns, but as any eyeglass wearer can tell you, walking into a warm room on a cold day or watching a football game in the rain can carry a whole different set of comfort issues.
Cosmetics
While most people focus on finding an eyeglass frame that suits them, the larger cosmetic issue may be their lenses. A person who is nearsighted will have lenses that are thick at the edge and thin in the middle. This makes their eyes appear smaller than they really are. Conversely, those who are farsighted have lenses that are thicker in the middle and their eyes will appear larger than they really are. These considerations disappear for contact lens wearers.
Risk and Time
Because contact lenses sit right on your eye, they pose a potential health risk. A lens that fits too tight or too loose can damage the cornea and poor hygiene and lens handling can lead to dangerous infection. That is why most eye doctors insist on regular yearly eye exams for their contact lens patients. Contact lens wearers should plan on investing more time on their eye care than their eyeglass wearing counterparts: more time at the doctor's office and more time cleaning and caring for their lenses.
Cost
While a pair of designer eyeglasses can be fairly expensive, over time contact lens wear will generally prove to be more costly. Frequency of eye exams, frequency of lens replacement and the added expense of cleaning solutions drive up the total cost of contacts. You must also keep in mind that most eye doctors will strongly recommend that contact wearers also have a pair of eyeglasses to fall back on when needed.
