Presbyopia is a medical condition related to vision in which there is a gradual loss of ability by the eye to focus on nearby objects in the field of view. This condition, which is felt to be due to the aging process, generally begins to affect persons in their mid or late 40s, at which time the eye muscles and the lens of the eye begin to lose resiliency. An inability to contract and bend the lens of the eye acutely enough to achieve a clear visual focus at a close range of vision is usually the result. Presbyopia treatment consists of providing a means for the eyes to again see well at close distances.
Eyeglasses are the most commonly used method of presbyopia treatment, and reading glasses are a popular type of eyeglasses. These pre-made glasses can be worn when focusing for a period of time upon objects within a close range, such as when reading or sewing. Reading glasses are easy to obtain without a prescription, are usually inexpensive. There are some drawbacks to using them, however; since they are primarily designed for viewing at a close visual range, they can cause eyestrain if they are used for mid-range viewing activities, such as when using a computer. Moreover, reading glasses will not help correct a visual condition known as myopia, or nearsightedness, which requires treatment by a vision specialist in ophthalmology or optometry.
Custom eyeglasses and contact lenses used for presbyopia treatment can be obtained with a prescription after being examined by an ophthalmologist or an optometrist. An ophthalmologist examines and treats eye disorders and/or eye disease by medical or surgical methods. An optometrist, on the other hand, examines the eyes and prescribes corrective lenses, but will refer to a medical or surgical specialist for further treatment.
Prescription eyeglasses for presbyopia treatment include bifocals, progressive addition lenses (PALs), or contact lenses. Vision with bifocals is somewhat limited, however, due to the sharp demarcation between a lower field of vision for close viewing, and an upper field of distance vision, with no intermediate zone of vision, such as when working at a desk or on a computer. In this regard, PALs allow the focus to gradually change from near vision at the bottom of the lens to far vision near the top of the lens, with a narrow intermediate zone in-between. Eyeglasses with this type of progressive vision adjustment are relatively expensive, however, and persons who perform a lot of mid-range focal activities sometimes use bifocals and purchase an additional pair of glasses designed solely for mid-range viewing.
Contact lenses made of bendable plastic, available in a wide variety of lens choices including color and types of lens, are another treatment for presbyopia. The gas permeable (GP) "breathable lenses" that were introduced in the early 1970s are considered an optimal choice by eye doctors due to their ability to allow oxygen to pass through the contact membranes. They also offer better resistance to bacteria than the more typical soft lens offers.
Presbyopia can also be treated by surgical methods. One type of surgery is called keratoplasty, which increases the curvature of the lens that has been lost due to aging — again improving the eye’s capability for near vision. Another type of surgery known as LASIK reshapes the curvature of the cornea — which governs the ability of the eye to focus — and allows the eye to again see nearby objects clearly.