As you reach middle age, the lens loses its flexibility to change shape and the ciliary muscle weakens. This results in light rays converging behind the retina rather than on it – and diminished ability to clearly focus on near objects such as print
Aging eyes, medically known as presbyopia (prez-bee-OH-pee-uh), is a condition in which the
lens of the eye gradually loses its flexibility, making it harder to focus clearly on close objects such as printed words. Distance vision is usually unaffected.
Presbyopia, which is named from the Greek words for "old eye," is part of the normal aging process and is easily treated with eyeglasses or contact lenses. LASIK and other types of surgery cannot prevent or remedy this natural occurrence, which affects nearly everyone by age 50. Once diagnosed, it should be treated quickly to prevent complicating other vision defects like nearsightedness,
farsightedness and astigmatism.
As the lens loses its elasticity, it becomes less capable of "bending" (with the help of the ciliary muscle, which also weakens with age) to properly focus light rays from different distances onto the retina. The more a lens can "bend," the closer the eye can focus.
Presbyopia usually becomes apparent in your early- to mid-40s, but this lens "stiffening" is actually a gradual process that begins decades earlier, sometimes in adolescence. The visual effects caused by presbyopia may slowly worsen for several years, requiring new changes in your lens prescription, but will stabilize by age 65 or 70.
Those who are farsighted (and already have trouble seeing near objects) may experience presbyopia earlier, as well as people who live in tropical climates and at sea level.
The first sign of presbyopia is often the need to hold reading material at arm's length the see letters clearly the reason why some eyecare professionals jokingly call it "long arm syndrome." In addition to blurred vision when reading or doing other close-vision activities at a distance that was previously comfortable, symptoms can include:
- Needing brighter light to see clearly
- Eye strain, fatigue or discomfort
- A decreased ability to see in darkness, and/or increased sensitivity to glare
- Headaches, due to muscle tension or strain as the eye tries to adjust the lens shape
If you are under age 40 and notice difficulty reading, contact your eye doctor because these symptoms could indicate health conditions such as anemia, diabetes, cardiovascular problems, infections, cataracts or sclerosis of the lens.
Unless you can stop Father Time, you can’t prevent presbyopia, as it is an inevitable part of aging. It is not caused, nor can it be prevented by lifestyle, diet or visual habits. However, some people who do a lot of close visual work such as intensive reading or computer work may develop it earlier than others. You can help minimize related eyestrain by taking a brief break from close visual tasks every hour or so, and by using bright light when reading.
Presbyopia is completely treatable with several types of corrective lenses. There is no surgical procedure that has been proven effective, and even those who undergo LASIK and other refractive surgeries will still be presbyopic.
- Progressives. These "no-line" lenses are the preferred choice for many presbyopes because they correct vision at every distance, eliminating the need for more than one pair of glasses. Plus, unlike bifocals and trifocals, they don’t have the distinct line separating the different visual fields, and have a more gradual variance in visual fields. Progressive lenses are custom-made to suit your specific work and leisure needs.
- Bifocals and trifocals. These lenses are sectioned into two or three parts that correct vision at different distances. Usually, the bottom portion of the lens corrects close vision, while the upper portion corrects distance vision (or is non-prescription). It may take several weeks to adjust to bifocal lenses, especially if you haven’t previously worn glasses.
- Single-vision reading glasses. If you previously didn’t need corrective lenses, so-called "reading" glasses may be an option. However, some presbyopes need more than one pair -- one for reading and another for driving, for example. Although inexpensive reading glasses are readily available at drug stores and other retails shops, they are often of poor quality and don't correct your vision as accurately as prescription lenses do.
- Multifocal contact lenses. Just like in multifocal eyeglasses (bifocals, trifocals and progressives), multifocal contact lenses correct more than one vision problem. Different parts of the lenses are corrected for sight at different distances. Designs include rigid gas permeable and soft progressive lenses.
- Monovision therapy. In this treatment approach, one contact lens is worn in one eye for close vision. Either another or no contact lens is worn in the other eye for distance vision. The brain needs some time to adjust to the different images received from each eye, but most people are able to see reasonably well at both near and far distances after an adjustment period ranging from a few hours to several months.