Presbyopia is an eye condition that usually occurs with age. As your eyes age, the lens begins to lose elasticity. In their 40s, many people begin to develop the symptoms of presbyopia. Because the lens has lost elasticity, it becomes more difficult to focus on things that are close to you. The distance begins to lengthen. Eventually near-sightedness and far-sightedness overlap, which is presbyopia.
Multifocal Contact Lenses
Multifocal contact lenses are used to correct presbyopia. More commonly, eyeglasses are used to correct it. Eyeglasses tend to have the best results for presbyopia sufferers. Just as bifocal lenses have two levels of corrective power, multifocal contact lenses create multiple levels of corrective power. There are two main types of multifocal lenses: simultaneous and translating. Recently a new type, hybrid multifocal lenses, has been developed.
Simultaneous vision lenses are available in soft or hard versions. Each area of simultaneous vision lenses has different powers. This type of multifocal lens allows eyes to focus on far and near objects at the same time. The different levels of power in the lens may be in distinctly separate areas of the lens, various zones that alternate through the lens, or may gradually change throughout the lens starting with one power and fading into the other. The gradual type can be difficult to get used to because your mind has to be selective in processing which areas of information are clear.
Translating or alternating vision lenses have two distinct areas of power. They are separated in much the same way that standard bifocal glasses are. The top half of the contact lens is used to see far away. The bottom half is for focusing up close. The lenses, like bifocal glasses, operate on the fact that we tend to look down while focusing on something up close. These are only available as hard lenses. These lenses are not best-suited for people who work on computers or with other middle-distance work. They're recommended for tasks like driving or reading because the two areas of power can be limiting.
Hybrid Multifocal Lenses
A new advance in multifocal lenses are hybrids. They combine a soft lens outer ring with a hard lens inner section. Multifocal contact lens wearers are often able to focus more clearly using hard lens. Hybrid lenses purport to allow the same crispness of vision without the long adjustment period of getting your eyes used to hard contact lenses.
Monovision refers to a prescription custom tailored by an eye care professional to your personal vision needs. It uses regular contact lenses. The lens for one eye will be tailored for focusing up close. The prescription for the other lens will be for focusing far away. Usually your dominant eye will have the near-sighted lens. Because our brains combine information from each eye into one picture, there is some adjustment time with monovision. After two to three weeks, your mind will get used to relying on one eye for reading and one for distance.