Later On

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Aging eyes

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A cheerful little email from Harvard Medical School, promoting their book The Aging Eye:

Like the rest of your body, your eyes naturally change throughout your life. But the effects become more apparent as you get older and the structures in and around your eyes become less efficient. For most people, the first sign of change is presbyopia, a deterioration in close-up vision. Luckily, this problem can be treated with reading glasses.

However, more serious age-related eye problems can cause vision loss or distortion. Almost 1 million Americans older than 40 are considered legally blind, and another 2.4 million have significantly reduced vision. Among all Americans over age 40, about 1 in 28 has some type of visual impairment.

The risk of developing vision problems increases as you get older, especially after age 65. One dramatic example: People age 80 or older make up about 8% of the U.S. population, but account for 69% of people who are blind.

There are four eye disorders that pose the greatest threats to vision in the later part of life: cataract, glaucoma, age-related macular degeneration, and diabetic retinopathy.

A cataract is a clouding of the lens that interferes with vision. Think of how cloudy a pane of glass appears when it is dirty — that’s how the eye’s crystalline lens appears when cataract develops. It generally takes years for the lens to become foggy, but the opacity eventually causes a disabling loss of vision, either by distorting light rays or keeping them from reaching the retina at all. Most people develop some opacity of the lens by age 60. Cataract occurs in about half of all people ages 65–74 and in about 70% of those older. Despite surgical advances, cataract remains the leading preventable cause of blindness in the world today, mainly because of limited access to health care in less developed countries.

Glaucoma is actually a group of eye diseases that cause vision loss through damage to the optic nerve.

Doctors used to think that high pressure within the eye, called intraocular pressure (IOP), was the primary cause of this damage, but we now know that other factors besides pressure must also be involved, because some susceptible people with “normal” IOP can experience vision loss from glaucoma. More than two million people in the United States have glaucoma, but at least half don’t know it because the early stages usually progress without symptoms. Glaucoma is a major cause of blindness and threatens 2% of people over 40, becoming even more common as people age. Yet early diagnosis and treatment can almost always save vision.

Age-related macular degeneration (AMD) strikes at the macula, the heart of the eye’s vision center. This small part of the retina, which measures only about 3 by 5 millimeters (less than one-quarter-inch square), is responsible for sharp, central vision. People with AMD often develop blurred or distorted vision and cannot clearly see objects directly in front of them. Eventually they may develop a blind spot in the middle of their field of vision that increases in size as the disease progresses.

Although the disorder eventually can become debilitating, in the earliest stages of AMD, there are no warning symptoms. If the condition progresses to intermediate AMD, some people begin to notice blurring in the center of their vision. At the advanced stage, the blurred area increases, making it hard to read or even recognize people. More than 7 million Americans have intermediate AMD, while 1.7 million have an advanced form that has progressed to the point of visual impairment.

Diabetic retinopathy, a complication of diabetes that can cause vision loss and blindness, occurs when abnormal blood sugar levels damage small blood vessels in the retina. This damage occurs in stages, and although the early changes may not affect how well you see, vision impairment is likely to occur as the condition progresses. So far there is no cure for diabetic retinopathy. But several options in laser surgery may help you to prevent vision loss, or at least slow its progression. Of course, one of the best ways to protect your vision is to control your blood sugar levels carefully. The Diabetes Control and Complications Trial found that people with diabetes who keep their blood sugar at near-normal levels cut their risk of developing eye disease by 75%.

Common eye myths examined

Myth: Eating carrots is good for the eyes.

Fact: There is some truth in this one. Carrots, which contain vitamin A, are one of several vegetables that are good for the eyes. But fresh fruits and dark green leafy vegetables, which contain more antioxidant vitamins such as C and E, are even better. Antioxidant vitamins may help protect the eyes against cataract and age-related macular degeneration. But eating any vegetables or supplements containing these vitamins or substances will not prevent or correct basic vision problems such as nearsightedness or farsightedness.

Myth: Staring at a computer screen all day is bad for the eyes.

Fact: Although using a computer will not harm your eyes, staring at a computer screen all day will contribute to eyestrain or tired eyes. Adjust lighting so that it does not create a glare or harsh reflection on the screen. Also, when you’re working on a computer or doing other close work such as reading or needlepoint, it’s a good idea to rest your eyes briefly every hour or so to lessen eye fatigue.

Finally, people who stare at a computer screen for long periods tend not to blink as often as usual, which can cause the eyes to feel dry and uncomfortable. Make a conscious effort to blink regularly so that the eyes stay well lubricated and do not dry out.

Written by Leisureguy

1 February 2007 at 1:45 pm

Posted in Daily life, Health, Medical

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