Eyesight problems, like nearsightedness, are common these days and often arise from childhood. It does not affect every person and many people go through early life with 20/20 vision. However, like every part of our body, the eyes undergo age-related changes which affect its function. This deterioration in vision is unavoidable and may affect some people to a greater degree than others. It is known as presbyopia.
What is presbyopia?
Presbyopia is a common eyesight problem where the vision is impaired as a person gets older, particularly when looking at close objects. We all will experience this vision disorder in life. While presbyopia is associated with aging, there is a misconception that it only affects much older people like those past 60 years of age. In fact presbyopia starts in the 40s and gradually worsens until the age of 65 years when it stabilizes.
Presbyopia should not be confused with other vision disorders like myopia (nearsightedness), hyperopia (farsightedness) or astigmatism. These vision disorders are common and can occur from earlier in life. Presbyopia will affect every person at some point in their life, irrespective of whether they these other vision disorders exist or not. It is estimated that about 150 million Americans have presbyopia to some degree or the other.
Causes of Presbyopia
In order to understand how presbyopia occurs, it is important to first understand how the eye works. Light enters the eye through the cornea (the clear transparent front part of the eye). The light rays are bent by the cornea so that a sharp image can be focused on the light-sensitive region at the back of the eye (retina). This bending of light (refraction) is necessary for visual acuity.
Light is further bent within the eyeball by the lens. This lens is elastic and its shape can be changed as needed. By changing the shape, light can be bent to a greater or lesser degree. This ensures that the light can be bent as required for the sharpest image. However, in presbyopia the lens loses some of this elasticity due to age-related changes. It therefore cannot bend the incoming light rays to the degree that is needed. This affects visual acuity.
Since the problem in presbyopia is with the bending of light passing through the eyeball, it is known as a refractive error. Nearsightedness, farsightedness and astigmatism are other types of refractive errors. Other age-related eye conditions include cataracts (clouding of the lens) and macular degeneration (breakdown of the light-sensitive part of the retina). While cataracts can severely impair the vision in the affected eye and age-related macular degeneration leads to blindness, presbyopia is not as serious.
Read more on common causes of bad eyesight.
Although presbyopia is considered to be a vision disturbance of people over the age of 40 years, it can sometimes occur earlier in life. This is uncommon and usually arises with conditions like multiple sclerosis, diabetes, cardiobascular diseases, and with the use of certain drugs for long periods of time. Premature presbyopia also arises with a loss of elasticity of the lens but not due to age-related changes. Depending on the underlying cause, it may at times be reversible to some degree.
Signs and Symptoms
Most people do not realize that they have presbyopia when it first arises. It is only when the vision is affected to a signficiant degree and tasks like reading or sewing become difficult that it becomes apparent to a person that their vision is deteriorating. When these symptoms start around the age of 40 years then presbyopia should be suspected. It develops gradually and continues to worsen until the age of around 65 years.
The signs and symptoms of presbyopia are not significantly different from other vision disorders, particularly other refractive errors.
- Difficulty focusing on objects nearby, often resulting in blurred vision.
- Clearer vision by holding objects further away.
- Headaches and eyestrain especially after doing work at a very close distance to the eye.
Other symptoms like clouding of the vision, halos and sudden changes of the vision may not be presbyopia and therefore need to be investigated further.
Diagnosis of Presbyopia
While the onset of presbyopia may be obvious depending on the age of a person, further tests are necessary to conclusively diagnose this vision disorder. These tests will also help exclude other conditions like cataracts and age-related macular degeneration which can affect vision later in life. Presbyopia can be diagnosed with a basic visual acuity test and a thorough eye examination is also necessary.
Always speak to an eye care professional about changes in vision. Even if the symptoms appear to be presbyopia, it is important to have an assessment by a professional to confirm the diagnosis. Early diagnosis of some of the more serious age-related conditions, like macular degeneration, can prevent complications such as blindness.
Treatment of Presbyopia
Treatment for presbyopia is not always immediately necessary. It is only once the condition is impairing vision to the point that daily life activities are affected that treatment is needed. Like other refractive errors of the eye, presbyopia can be corrected with eyeglasses, contact lenses and surgery.
- Eyeglasses: Reading glasses, bifocals and trifocals.
- Contact Lens: Bifocal, monovision and modified monovision.
- Surgery: Refractive surgery, lens implants and corneal inlays.
Surgical correction of presbyopia is rarely needed. It is often done when a person chooses surgery over the use of eyeglasses or contact lens. Some surgical procedures for presbyopia, like refractive surgery, is irreversible. Therefore other options like corneal inlays may be preferable as it can be removed if required.
Read more on refractive eye surgery.
Can presbyopia be prevented?
Presbyopia is a natural consequence of aging. There is no known way to prevent it. Early (premature) presbyopia can be avoided with proper management and treatment of known risk factors. However, this type of prebyopia is rare. Nutritional supplements cannot prevent or slowdown presbyopia as is the case to some degree with age-related macular degeneration.
However, some of the symptoms of presbyopia like headaches and eyestrain can be prevented by correcting the eyesight. Other simple measures may also be useful for symptomatic relief. Reducing long hours of close work like staring at screens, resting the eyes every 20 minutes and changing the lighting in a room can help prevent eyestrain and headaches associated with presbyopia.