Eye Facts About Presbyopia
Presbyopia, which means "old eye" in Greek, is the gradual loss of the eye's ability to see things up close. Around the age of 40, many people start complaining that "their arms are not long enough" to read a menu or a telephone book. This familiar event is often the first sign of Presbyopia, which can, if uncorrected, cause eye fatigue and headaches.
What causes Presbyopia?
To see both near and distant objects clearly, the lens of the eye changes shape, getting thicker and thinner as you focus on an object.
When we are young, the lens of the eye is soft and flexible. To see something up close, like print, the ciliary muscle inside the eye contracts. This causes the lens to thicken, which adds focusing power to the eye. To look at something far away, the ciliary muscle relaxes, which causes the lens to flatten. When the lens is soft and flexible, it can easily respond to the movement of the ciliary muscle. As we age, the lens loses its flexibility or the power to accommodate. When this happens, most people begin to have difficulty reading and performing other close-up tasks.
No medications, supplemental vitamins, or exercises can stop or reverse the normal aging process responsible for Presbyopia.
Lens
To see something up close the ciliary muscle contracts, to focus on something at a distance it relaxes. As we age, our lens loses the ability to accommodate the movement of the ciliary muscle, resulting in Presbyopia.
Glasses
Reading glasses, the traditional tool for dealing with Presbyopia, help bend light rays before they enter the eye to compensate for the loss of focusing ability.
People who have good distance vision usually wear half-glasses: no lens on the top and a reading prescription on the bottom. Half-glasses can be purchased at your local drugstore. Start with the lowest magnification you need to read comfortably, and increase the power as you get older.
Prescription reading glasses are also available if you want more choices in frame styles or have particular visual needs. Prescription reading glasses can be made as a bifocal, trifocal, or no-line bifocal (progressive lens) and are widely used by people of all ages. Bifocals provide correction for both near and far vision. Trifocals add correction for the intermediate distance. A progressive lens has a continuous, gradual change in prescription from eye level to the bottom of the lens, providing correction for all distances.
Contact Lenses
For those who prefer contacts to glasses, there are two options. The most common is to correct one eye for distance and the other for near vision - a concept called monovision. Despite some loss in depth perception, many people adapt to this arrangement quite well.
Bifocal contact lenses, a second option, can be made a number of different ways. One kind of bifocal lets you read when you look down. Other types let you read in any position, but may cause annoying ghost images, haziness or color fringes.
CK (conductive keratoplasty)
CK is a procedure for those who have good distance vision but struggle with fine print in reading newspaper, menus and working with the computer. In CK radio waves are used to reshape the cornea. A small probe is applied in a circular pattern on the outer cornea to shrink small areas of collagen. This circular shrinkage creates a constrictive band (like tightening of a belt), increasing the overall curvature of the cornea to bring near vision back into focus.
Near vision CK does not stop the clock from ticking but it can turn back the hands by temporarily steepening your cornea in one eye for near vision while using the other for distance vision. Presbyopia is a progressive condition and therefore, patients may require additional treatments to maintain their near vision.
Can refractive surgery correct Presbyopia?
No, refractive surgery cannot correct Presbyopia. However, some people choose refractive surgery such as LASIK, PRK, or CK to achieve monovision, where the procedure corrects one eye for distance and the other for near vision, just as with contact lenses. You may wish to consider trying monovision with contact lenses before surgery to determine your individual needs and your ability to adapt to this correction.
Presbyopia is part of the natural process of aging. The most appropriate correction for you depends on your eyes and your needs. You should discuss your refractive errors and your lifestyle with your opthalmologist to decide on which correction will be most effective for you.
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