As we age, our bodies undergo many significant changes. One such change that often causes concern for people is the gradual loss of near vision that occurs when we reach our 40’s. This normal and unavoidable effect of aging is called presbyopia, or “old eyes.”
The symptoms for presbyopia are familiar to anyone over age 45. At first, you will notice that after you’ve been reading for a short time, the words seem to run together. After a brief rest, you can again read for a short time before it happens again. Over time, reading small print – such as numbers in the phone book, the box scores in the newspaper, or items on a menu – becomes harder and then impossible. You may notice that if you hold reading material farther away than normal, the words come into sharper focus. As presbyopia continues to develop, you may find yourself hold your newspaper farther and farther away until at last your arms aren’t long enough to compensate.
Presbyopia arises due to changes in the lens of the eye. Like in a camera, the lens of the eye is responsible for adjusting focus. When we are young, we can easily change focus to look at objects that are nearby or far away. This is because our lens is young and soft and can quickly and easily change its shape to accommodate between distance and near focus. But as we age, the lens becomes stiff and can no longer easily change its shape. As a result, we can no longer adjust our focus to see up close without some help. This most commonly starts around age 42, but can come on a few years earlier in some people, and show up later in others.
Help for presbyopia comes in the form of glasses, contact lenses, or refractive surgery. If you do not use glasses for distance vision, then a pair of reading glasses is the easiest solution. Reading glasses are necessary only for up-close tasks such as reading or sewing, and must be removed to see clearly off at a distance. Reading glasses come in different strengths. Usually weak reading glasses (in the range of +1.25 to +1.50 diopters, or focusing units) will work well when presbyopia symptoms are just beginning, and stronger glasses will be needed every few years until presbyopia stops getting worse, usually in your late 50’s to early 60’s. Once presbyopia stops progressing, most people end up with reading glasses in the range of +2.50 to +2.75 diopters. If you do use glasses for distance vision even before presbyopia starts, the solution for you will involve bifocals. Bifocals are glasses that have your distance prescription in the top of the lens and your presbyopic reading prescriptions in the bottom of the lens. The strength of the bifocal part of the lens will have to be increased over the years as presbyopia progresses, just as with reading glasses. Monofocal, bifocal, and multifocal contact lenses are often prescribed to assist with presbyopia.
Refractive surgery options are also available to presbyopic patients. Refractive Lens Exchange involves taking out the natural lens in the eye replacing it with an intraocular lens that corrects both distance and near vision. These presbyopic-correcting lenses may be either accommodative or multifocal.