Bifocal Contact Lenses

March 27, 2009 by admin  
Filed under Bifocals

As people age, their ability to focus on near and far distances, weakens, hence the need for bifocal contact lenses. The medical term for this is Presbyopia. Once adults hit their 40s, they begin to notice a lack of ability to focus. This is a natural part of ageing and is progressive. In the normal performing eye, the natural lens, which is shaped like a large lentil (about 10 mm in diameter), is attached to muscles which contract or relax to change the shape of the lens.The changing lens shape helps light to be focused in response to the need for clarity. For the adult with Presbyopia, the muscles have begun to lose their flexibility to focus. With this loss, the eyes have a harder time in focusing. Other symptoms of this condition are eyestrain, headaches and squinting. What bifocal contact lenses do is provide patients the balance to look at near and far distances with clarity. This is why bifocal contact lenses have two different prescriptions in them.

The way bifocals work is, the main part of the lenses will have the prescription for nearsightedness or farsightedness, whereas the lower portion of the lens will hold the stronger near prescription for close work.

There are also different designs when it comes to bifocal contact lenses. The traditional design is very similar to the bifocal glasses and ahs two distinct vision corrections, one on top and one on bottom. However, new technology has created the progressive bifocal contact lens and the two different powers are used on the lens in a progressive way. In these types of lenses the eye has to learn which power to use for the distance of the object you are viewing. Some people have problems getting used to this type of lens, while others simply love them and are happy not to have to wear glasses. The only way to find out is to simply talk to your optometrist and give the bifocal contact lenses a shot.

Types of Bifocal Contact Lenses

People who need bifocals to see now have the option of wearing bifocal contact lenses instead of glasses. There are three main types of bifocal contact lenses and two alternative types of bifocal contact lenses:
1. Concentric lenses are shaped sort of like bull’s-eyes, with the near prescription on the inside ring and the far prescription on the outside ring, or vice versa. Between these two main rings, a "multi-focal" or medium prescription ring may be placed if you need it.
2. Aspheric multifocal contact lenses contain both the far and near prescriptions in the center of the lens. The eye will simply ignore the prescription it doesn’t currently require.
3. Translating lenses are set up so that the near, far (and medium if necessary) prescriptions lay in three distinct locations within the lens. Because of this, some translating lenses are truncated or "weighted" on the bottom so that no slippage will occur and mess up the wearer’s vision or disorient him or her.
4. Hybrid Bifocal lenses divide the near and far prescriptions. This means the near prescription could be in the middle of the left eye and the far prescription could be in the middle of the right eye or vice versa, with a "medium" blend in the surrounding circle.
5. Monovision is very similar to hybrid, with one exception: there is no "medium" prescription. The wearer simply learns to use the right eye for items far away and the left eye for items in the foreground.
Between all of the above types of bifocal contact lenses, no matter what your seeing ailment is, you’re covered!

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