Presbyopia usually occurs beginning at around age 40, when people experience blurred near vision when reading, sewing or working at the computer.
Presbyopia Symptoms And Signs
When people develop presbyopia, they find they need to hold books, magazines, newspapers, menus and other reading materials at arm’s length in order to focus properly. When they perform near work, such as embroidery or handwriting, they may develop headaches, eye strain or feel fatigued.
What Causes Presbyopia?
Presbyopia is caused by an age-related process. This differs from astigmatism, nearsightedness and farsightedness, which are related to the shape of the eyeball and are caused by genetic and environmental factors. Presbyopia generally is believed to stem from a gradual thickening and loss of flexibility of the natural lens inside your eye. These age-related changes occur within the proteins in the lens, making the lens harder and less elastic over time. Age-related changes also take place in the muscle fibers surrounding the lens. With less elasticity, the eye has a harder time focusing up close. Other, less popular theories exist as well.
Presbyopia Treatment: Eyeglasses
Eyeglasses with bifocal or progressive addition lenses (PALs) are the most common correction for presbyopia. Bifocal means two points of focus: the main part of the spectacle lens contains a prescription for distance vision, while the lower portion of the lens holds the stronger near prescription for close work. Progressive addition lenses are similar to bifocal lenses, but they offer a more gradual visual transition between the two prescriptions, with no visible line between them. Reading glasses are another choice. Unlike bifocals and PALs, which most people wear all day, reading glasses typically are worn just during close work. If you wear contact lenses, your eye doctor can prescribe reading glasses that you wear while your contacts are in. You may purchase readers over-the-counter at a retail store, or you can get higher-quality versions prescribed by your eye doctor.
Presbyopia Treatment: Contact Lenses
Presbyopes also can opt for multifocal contact lenses, available in gas permeable or soft lens materials. Another type of contact lens correction for presbyopia is monovision, in which one eye wears a distance prescription, and the other wears a prescription for near vision. The brain learns to favor one eye or the other for different tasks. But while some people are delighted with this solution, others complain of reduced visual acuity and some loss of depth perception with monovision. Because the human lens continues to change as you grow older, your presbyopic prescription will need to be increased over time as well. You can expect your eye care practitioner to prescribe a stronger correction for near work as you need it.
Presbyopia Treatment: Surgery
Surgical options to treat presbyopia also are available. One example is Refractec Inc.’s conductive keratoplasty or NearVision CK treatment, which uses radio waves to create more curvature in the cornea for a higher “plus” prescription to improve near vision. The correction is temporary and diminishes over time. The procedure is performed on one eye only for a monovision correction.
LASIK also can be used to create monovision, in which one eye is corrected for near vision while the other eye is stronger for distance vision. With the recent introduction of presbyopia-correcting intraocular lenses, some people undergoing cataract surgery may be able to achieve clear vision at all distances. Also, an elective procedure known as refractive lens exchange may enable you to replace your eye’s clear but inflexible natural lens with an artificial presbyopia-correcting lens for multifocal vision. This is essentially cataract surgery, but it’s performed on people who don’t have cataracts for the purpose of providing all-distance vision.