When we started to notice some visual disorder, some may assume that it is long-sightedness, meaning that we may only use our eyes to see only far objects without lenses. But there is a visual disorder called presbyopia which may enlighten us. Presbyopia is the gradual loss of your eyes' ability to focus on nearby objects. It's a natural, often annoying part of aging, which usually becomes noticeable in around 40 years of age and continues to worsen until around age 65.
Causes of presbyopia When you’re young, the lens in your eye is flexible and relatively elastic. It can change its length or shape with the help of a ring of tiny muscles that surround it. The muscles that surround your eye can easily reshape and adjust your lens to accommodate both close and distant images. With age, your lens loses flexibility and begins to stiffen. As a result, your lens becomes unable to change shape and constricts to focus on close images. With this hardening of your lens, your eye gradually loses its ability to focus light directly onto your retina.
To form an image, your eye relies on the cornea and the lens to focus the light reflected from objects. The closer the object, the more the lens flexes. • The cornea is the clear, dome-shaped front surface of your eye. • The lens is a clear structure about the size and shape of an M&M's candy. • Both of these structures bend (refract) light entering your eye to focus the image on the retina, located on the inside back wall of your eye. The lens, unlike the cornea, is somewhat flexible and can change shape with the help of a circular muscle that surrounds it. When you look at something at a distance, the circular muscle relaxes. When you look at something nearby, the muscle constricts, allowing the relatively elastic lens to curve and change its focusing power.
Presbyopia is caused by a hardening of the lens of your eye, which occurs with aging. As your lens becomes less flexible, it can no longer change shape to focus on close-up images. As a result, these images appear out of focus. You may become aware of presbyopia when you start holding books and newspapers at arm's length to be able to read them
Symptoms of presbyopia The most common symptoms of presbyopia occur around age 40 for most people. The symptoms of presbyopia typically involve a gradual deterioration in your ability to read or do work up close. Common symptoms of presbyopia are: • having eyestrain or headaches after reading or doing close work • having difficulty reading small print • having fatigue from doing close work • needing brighter lighting when reading or doing close work • needing to hold reading material at an arm’s distance to focus properly on it • overall problems seeing and focusing on objects that are close to you • squinting Hyperopia, or farsightedness, is a condition that has symptoms similar to presbyopia. However, they’re two different disorders. In both conditions, distant objects are clear, but closer objects appear blurry. It occurs when your eye is shorter than normal or your cornea is too flat. With these malformations, the light rays focus behind your retina, as in presbyopia. However, hyperopia is a refractive error that’s present at birth. It’s possible to have hyperopia and then develop presbyopia with age.
Risk factors for presbyopia The most significant risk factor for presbyopia is age. Most people lose some ability to focus on close objects by age 40. It affects everyone, but some people notice it more than others. Certain diseases or drugs can cause presbyopia in people younger than age 40. When the symptoms of presbyopia occur earlier than usual, it’s called premature presbyopia. If you notice the symptoms of presbyopia at an age earlier than the normal onset, it may be a sign of an underlying medical condition. You’re at a higher risk of premature presbyopia if you have: • anemia, which is a lack of enough normal blood cells • cardiovascular disease • diabetes, or difficulty metabolizing blood sugar • hyperopia, or farsightedness, which means you have a greater difficulty seeing objects nearby than objects that are far away • multiple sclerosis, which is a chronic illness that affects your spine and brain • myasthenia gravis, which is a neuromuscular disorder that affects your nerves and muscles • eye trauma or disease • vascular insufficiency, or poor blood flow Some prescription and over-the-counter drugs can reduce your eye’s ability to focus on close images. Taking the following drugs can put you at a higher risk of premature presbyopia: • alcohol • antianxiety drugs • antidepressants • antihistamines • antipsychotics • antispasmodics • diuretics Other factors that may put you at a higher risk of premature presbyopia are: • being female • having intraocular surgery, or surgery done on the inside of the eye • eating an unhealthy diet • having decompression sickness, or “the bends,” which results from rapid decompression and typically occurs in scuba divers that surface too quickly
What are the different types of presbyopia? There are five types of presbyopia: • Premature presbyopia: Presbyopia occurring before the age of 40 years. • Incipient presbyopia: It is the earliest stage when it may be a bit more difficult to read small prints. • Functional presbyopia: This occurs when patients begin to notice more problems with near sight. • Absolute presbyopia: Eyes cannot focus on near objects at all. • Nocturnal presbyopia: Eyes cannot focus on near objects in low light conditions.
Diagnosis of presbyopia Contact your doctor or eye specialist if you have any of the symptoms of presbyopia. Even if you’re not experiencing symptoms, you should have an eye examination by age 40. According to the American Academy of Ophthalmology, adults who don’t have any symptoms or risk factors associated with eye disease should have a baseline examination at age 40. An eye screening can identify early signs of disease and vision changes that can begin, sometimes without any symptoms, around this age. Presbyopia can be diagnosed as part of a comprehensive eye examination. A typical exam will include tests to evaluate your eyes for the presence of diseases and vision disorders. Your pupils will probably be dilated with special eye drops to allow your doctor to examine the inside of your eye.
Complications of presbyopia If your presbyopia is undiagnosed or uncorrected, your vision will likely deteriorate gradually. It will increasingly affect your lifestyle over time. You may experience a significant visual disability if a correction isn’t made. You’ll develop problems maintaining your usual levels of activity and productivity at work and in everyday activities. When tasks such as reading small print become difficult and remain untreated, you’re at risk of headaches and eyestrain. Because everyone develops presbyopia as they age, it’s possible to have presbyopia in addition to another type of eye problem. Presbyopia can occur in combination with: • astigmatism, which is an imperfection in the curvature of your cornea that causes blurred vision • hyperopia, or farsightedness • myopia, or nearsightedness It’s also possible to have a different type of eye problem in each eye.
Outlook for presbyopia In most cases, the vision you’ve lost to presbyopia can be corrected with eyeglasses, contact lenses, or surgery. The gradual decline of the elasticity required to focus your lens on near objects continues until about age 65, which is when most of the elasticity is gone. However, even at that point, correction to see close objects is possible.
Treatment of presbyopia No cure exists for presbyopia. However, there are several treatments available to correct your vision. Depending on your condition and lifestyle, you may be able to choose from corrective lenses, contact lenses, or surgery to correct your vision.
Nonprescription lenses If you didn’t need eyeglasses before getting presbyopia, you might be able to use nonprescription reading glasses. These readers are typically available at retail stores, such as drug stores. They typically work best for reading or close work. When selecting a pair of nonprescription reading glasses, try different degrees of magnification. Choose the lowest magnification that allows you to read a newspaper comfortably.
Prescription lenses You’ll need prescription lenses for presbyopia if you can’t find an appropriate magnification from the nonprescription offerings. You’ll also need a prescription if you already have lenses to correct another eye problem. There are several variations of prescription lenses, such as the following: • Prescription reading glasses can be used if you have no eye problems other than presbyopia and prefer not to purchase your glasses off the shelf. • Bifocals have two different types of focus, with a noticeable line between them. The upper portion is set for distance while the lower portion is set for reading or close work. • Progressive lenses are similar to bifocal lenses. However, they don’t have a visible line, and they offer a more gradual transition between the distant and close portions of the prescription. • Trifocals have three different points of focus. The portions are set for close work, mid-range, and distance vision, and they can be made with or without visible lines. • Bifocal contact lenses provide the same option as bifocal glasses. • Monovision contact lenses require you to wear a contact lens set for distance vision in one eye and a different contact lens set for close work in your other eye. • Modified monovision contact lenses require you to wear a bifocal contact lens in one eye and a contact lens for distance in your other eye. Both eyes are used for distance, but only one eye is used for reading, and your brain adjusts as needed to process the image. Your eyes will continue to gradually lose their ability to focus on close objects as you age. As a result, your prescription will have to be reviewed and changed according to the advice of your eye specialist.
Surgery There are several surgical options to treat presbyopia. For example: • Conductive keratoplasty (CK) involves using radiofrequency energy to change the curvature of your cornea. While it’s effective, the correction may diminish over time for some people. • Laser-assisted in-situ keratomileusis (LASIK) can be used to create monovision. This adjustment corrects one eye for near vision and the other eye for distance. • Refractive lens exchange involves the removal of your natural lens. It’s replaced with a synthetic lens, called an intraocular lens implant, inside your eye.
How to prevent presbyopia There’s no proven technique for preventing presbyopia. The gradual decline of the ability to focus on near objects affects everyone. You can help protect your vision with these steps: • Get regular eye examinations. • Control chronic health conditions that could contribute to vision loss, such as diabetes or high blood pressure. • Wear sunglasses. • Wear protective eyeglasses when participating in activities that could result in eye injury. • Eat a healthy diet with foods containing antioxidants, vitamin A, and beta carotene. • Make sure you’re using the right strength of eyeglasses. • Use good lighting when reading.
Talk to your doctor or eye specialist about any changes in your vision or eye health. Many eye diseases and conditions can benefit from early intervention and treatment.
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