What is presbyopia?
Presbyopia is the normal worsening of vision with age, especially near vision. As you approach middle age, the lenses in your eyes begin to thicken and lose their flexibility. This makes it harder for your eyes to focus on objects at varying distances.
Depending on how far away an object is, a muscle surrounding the lens in your eye will either expand or contract. With presbyopia, the muscle may not work as well. Also, the lens loses much of its flexibility. This makes it harder for the lens to bend enough to bring close objects into focus. As a result, images are focused behind the retina instead of directly on it, leaving close vision blurred. Putting greater distance between the object and your eye brings the object into focus. For example, holding a newspaper farther from your face helps you see the words.
What causes it?
Presbyopia is a natural part of aging. As you grow older, the lenses in your eyes thicken. They lose their elasticity, and the muscles surrounding the lenses weaken. Both these changes decrease your ability to focus, especially on near objects. The changes take place gradually, though it may seem like it happens quickly.
Near vision gets worse because of presbyopia starting around age 40. It gradually gets worse. Then it stabilizes around age 60.
What are the symptoms?
The main symptom of presbyopia is blurred vision, especially when you do close work or try to focus on near objects. This is worse in dim light or when you are fatigued. Presbyopia can also cause headaches or eyestrain.
How is it diagnosed?
Presbyopia can often be diagnosed with a general eye exam. Your doctor will test your visual acuity (sharpness of vision) and how your eyes change focus from near to far. They'll also check the muscles in your eyes and the condition of your retinas. Measurements may be taken for glasses or contact lenses.
How is presbyopia treated?
Presbyopia can usually be corrected with glasses or contact lenses. If you didn't need glasses or contacts before presbyopia appeared, you can probably correct your eyesight by using reading glasses for close work. Glasses you buy without a prescription may be sufficient. But check with your eye doctor to find out the right glasses for you. If you do buy glasses without a prescription, try out a few different pairs of varying strength (magnification) to make sure you get glasses that will help you read without straining.
If you already use glasses or contacts to correct nearsightedness, farsightedness, or astigmatism, you'll need a new prescription that will also correct presbyopia. You may wish to use bifocals, in which distant vision is corrected at eye level and close vision is corrected at the bottom. Other options include trifocal glasses, which can correct for distant, near, and middle vision; progressive lenses, which give a smooth transition between distant, middle, and near vision; multifocal contact lenses; or monovision contact lenses, which correct distant vision in your dominant eye and close vision in your weaker eye. Your prescription may have to be changed over time as presbyopia gets worse.
If you don't want to wear glasses or contacts, surgery such as LASIK may be an option. LASIK uses lasers to reshape the cornea of your eye. Laser surgery cannot give you both distance and near vision in the same eye. But your doctor can correct one eye for distance vision and the other eye for near vision.
Another surgery option is clear lens extraction with an intraocular lens implant, in which the natural lens is removed and an artificial one is implanted to replace it. Some lens implants correct either distance or near vision. Others (called multifocal implants) correct both near and distance vision.
None of these surgeries will restore perfect vision. You will have to compromise. For example, you may have surgery to correct distance vision and then use reading glasses for near vision. Or you may have one eye adjusted for near vision and one for distance vision, which would reduce your depth perception. New procedures that reverse presbyopia are being developed and tested.