Overview of Presbyopia
A person with presbyopia has difficulty focusing on close objects. The condition is similar to hyperopia, but the underlying cause is different.
In presbyopia, the crystalline lens has become less flexible and the eye muscles that support the lens and allow it to accommodate have weakened. The crystalline lens is composed like an onion. The nucleus is surrounded by the cortex, and the cortex is surrounded by the lens capsule. The lens is an elastic structure that changes shape, or accommodates, to focus on objects at various distances. When focusing on distant objects, the lens becomes flatter. When focusing on close objects, it becomes rounder.
Symptoms of presbyopia may seem to occur suddenly, but the condition develops over several years, as the lens capsule loses its ability to expand as a person ages. The result is that while distant objects are seen clearly, close objects are blurred because the lens cannot resume the shape that it needs to bring them into focus.
Presbyopia can complicate other vision conditions. For example, mildly farsighted people suddenly may find that they need glasses. Prior to becoming presbyopic, their eyes may have been able to accommodate, avoiding the need for corrective lenses. With the onset of presbyopia, they no longer see close objects clearly.
Incidence and Prevalence of Presbyopia
Virtually everyone experiences some degree of presbyopia when they reach middle age. Most people begin to notice presbyopia in their early to mid-forties, although symptoms occasionally become noticeable during the late thirties. The ability to focus continues to decrease until about the age of 55.
Risk Factors for Presbyopia
Presbyopia is a normal part of aging.
Signs and Symptoms of Presbyopia
The first symptom of presbyopia is usually the momentary blurring of distant objects that occurs after doing close work. For example, if a man is reading and then looks up and across the room at his wife, her image is blurry for a few moments. This occurs because the crystalline lens can no longer rapidly change focus (accommodate) from near to far. As time goes on, it takes longer to refocus. Other symptoms include:
- Blurry vision of close objects
- Difficulty reading small print
- Eye fatigue, especially when reading in poor lighting or at the end of the day
- Eyestrain and headache when doing close work
- Holding reading material at arm's length to see it clearly
Symptoms can worsen in the morning or when the eyes are tired. Poor lighting may exacerbate symptoms.
A diagnosis of presbyopia can be made only after a basic eye examination performed by an ophthalmologist or an optometrist.
Treatment for Presbyopia
Treatment depends on the patient's age, lifestyle, occupation, and the presence of other eye conditions. If focusing on close objects is the problem, a pair of reading glasses may correct vision satisfactorily. Those who have difficulty focusing on both near and distant objects may need bifocals or two pairs of glasses.
Monovision is another treatment option in which the physician corrects one eye to see distant objects and one to see near objects. This can be done with either contact lenses, refractive surgery, or implanted intraocular lenses.
In April 2015, the U.S. Food and Drug Administration (FDA) approved the KAMRA inlay to treat certain people between the ages of 45 and 60 affected by presbyopia who have not had cataract surgery. This device is implanted in the cornea of one eye to correct near vision.
The KAMRA inlay is implanted into a pocket in the cornea, which is created by an eye surgeon using a laser. The device blocks unfocused, peripheral light rays while allowing central light rays to pass through an opening at the center of the inlay. Certain people, including those who have had cataract surgery, those who have severe dry eye, those with corneal abnormalities, and others are not good candidates for this procedure. Vision-related problems (temporary or permanent) and other complications may occur.
Presbyopia cannot be prevented. Between the ages of 45 and 65, the condition continues to cause changes in the eye in most cases, necessitating new prescriptions for eyeglasses or contact lenses. It is advisable to have an eye exam every 2 to 3 years. More frequent visits may be needed if changes in vision occur more rapidly.
Updated by Remedy Health Media