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Healthy Eyes and Low Vision Care

 

Course Number	LWH801
Objectives	At the end of this course, you will  1) how your eyes functions, 2) how to prevent eye problems, 3) the types of refractive errors, and 4) the common low vision and eye disease problems.
Credit Hours and Fee	3.0 CE Credit Hours with a fee of $24.00
Instructor	Rudolf Klimes, PhD (Indiana University), MPH (Johns Hopkins University); Adjunct Professor at Folsom Lake College, Folsom CA.

Welcome to this 3-contact-hour Continuing Education  course with instant online processing and certification 24/7.  Study the course below, take the 12-question multiple-choice TEST, register and pay online. If you score 75% or above, you may print your CE certificate on your printer as soon as you finish. If you have difficulty printing your certificate, click here. You may retake the test once.

 

1. The Eyes

The human eye is composed of many parts that work together. They receive visual images, focus them properly, and send messages to the brain. To have vision, you must have three things: (1) eyes, (2) a brain, and (3) light.

Light rays bounce off an object you are looking at. Let's say the object is a dog. The light reflects off the dog's image and comes back to your eye. It then enters through the outer part of the eye, called the cornea. The cornea is clear like a window. The cornea helps the eye to focus. 'To focus' means to make things look sharp and clear. Next, the light rays go through an opening called the pupil. The pupil is the dark round circle in the middle of the colored part of your eye. The colored part is called the iris. The pupil is really a hole in the iris. The iris controls how much light goes into your eye.

When the light is bright, the iris closes the pupil until the right amount of light gets in. When the light is dim, the iris opens the pupil to let in more light. All of this happens automatically. You do not have to tell your eye to do it! Your eye has a lens to focus the rays of light. The lens of the eye is behind the iris. Light passes through the lens on its way to the back of the eye.

The back of the eye is very important. Lining the inside of the eye is the retina. The retina includes 130 million tiny light-sensitive cells that send messages to other cells. These cells come together at the back of the eye to form the optic nerve. The optic nerve is part of the brain. Fortunately for you, your brain decides how you see. The retina sees the world upside down, but the brain turns it right side up.When you look at an object, each eye sees a slightly different picture. The brain combines the images, or pictures, that each eye sees and makes them into one picture. Source: http://www.nei.nih.gov

The eye is the organ of sight, a nearly spherical hollow globe filled with fluids (humors). The outer layer or tunic (sclera, or white, and cornea) is fibrous and protective. The middle tunic layer (choroid, ciliary body and the iris) is vascular. The innermost layer (the retina) is nervous or sensory. The fluids in the eye are divided by the lens into the vitreous humor (behind the lens) and the aqueous humor (in front of the lens). The lens itself is flexible and suspended by ligaments which allow it to change shape to focus light on the retina, which is composed of sensory neurons.

Many people think of eye problems as something that happens to older people, but in fact, there are many eye conditions that can affect people in all stages of life — even childhood.

Some of the eye conditions that can threaten a child's vision are hard to detect, so children should have an eye and vision screening before age 5. Early detection and treatment of childhood eye conditions such as strabismus and amblyopia can help ensure a lifetime of good vision. Most young adults have healthy eyes, but accidental injury is one of the leading causes of vision loss in this age group. Sports, yard work, harsh chemicals — even jump-starting a car — can be hazardous to the eyes. Make sure you always wear the appropriate protective eyewear during these activities. Some of the eye problems that harm the vision of older people actually start much earlier. Many of them can be effectively treated and vision preserved if caught early enough. Ask your Eye M.D. if you may be at risk for problems like glaucoma or diabetic eye disease, and how often you should have an eye exam. Some vision changes are natural as we get older. Most of these can be adequately corrected with glasses, contacts or refractive surgery. However, sudden or frequent changes may signal a problem and should prompt a visit to the Eye M.D. Because seniors are at increased risk for serious eye problems, they should have more frequent eye exams. Please check with your Eye M.D. about a schedule that is right for you. In general, from ages 40 to 64, you should have an eye exam every two to four years. After age 65, you should increase that to once every one to two years, and even more frequently if your Eye M.D. recommends it. People sometimes accept eye problems like decreasing or cloudy vision, or dry or teary eyes as an unavoidable condition of aging. Most of these problems, however, can be corrected and improved with the right treatment. Talk to your Eye M.D. if you have any eye problem that bothers you. Even if poor vision can't be improved, you can still enjoy an active and independent lifestyle. Many Eye M.D.s offer low vision rehabilitation or can refer patients to these services.

Seeing your doctor regularly to check for diseases like diabetes, which could cause eye problems if not treated. Having a complete eye exam with an eye specialist every 1 to 2 years. Most eye diseases can be treated when they are found early. The eye doctor should enlarge (dilate) your pupils by putting drops in your eyes. This is the only way to find some eye diseases that have no early signs or symptoms. The eye doctor should test your eyesight, your glasses, and your eye muscles. You should also have a test for glaucoma.

More Americans than ever are facing the threat of blindness from age-related eye disease, a new report says. Over one million Americans aged 40 and over are currently blind and an additional 2.4 million are visually impaired. These numbers are expected to double over the next 30 years as the Baby Boomer generation ages.

2. Eye Problem Prevention

2.1 Eat a balanced diet. See www.learnwell.org/nutri.htm

2.2 Dietary Supplement

A dietary supplement with high levels of antioxidants and zinc significantly reduces the risk of advanced age-related macular degeneration (AMD) by about 25 percent. These same supplements also reduce the risk of vision loss caused by advanced AMD by about 19 percent. They have no significant effect on the development or progression of cataract.

These results are from the Age-Related Eye Disease Study (AREDS), a major clinical trial sponsored by the National Eye Institute, one of the Federal government's National Institutes of Health. The supplements are not a cure for AMD, nor will they restore vision already lost from the disease. However, they may play a key role in helping people at high risk for developing advanced AMD keep their vision.

Who Should Take the Supplements?

People who are at high risk for developing advanced AMD should consider taking the supplements used in the study. Your eye care professional can tell you if you have AMD and if you are at risk for developing the advanced form of the disease. The doctor should give you a dilated eye exam in which drops are placed in your eyes. This allows for a careful examination of the inside of the eye to look for signs of AMD.

If you are already taking daily multivitamins and your doctor suggests you take the dietary supplements used in the AREDS, review all the supplements with your doctor.

What is the Dosage of the Supplements Used in the Study?

The specific daily amounts of antioxidants and minerals used by the study researchers were 500 milligrams of vitamin C; 400 International Units of vitamin E; 15 milligrams of beta-carotene; 80 milligrams of zinc as zinc oxide; and two milligrams of copper as cupric oxide. Copper was added to the AREDS formulations containing zinc to prevent copper deficiency, which may be associated with high levels of zinc supplementation.

Where Can I Obtain the Supplements?

Bausch and Lomb, an eye care company, was a collaborator in the AREDS and provided the study supplements. The company markets the formulation used in the AREDS; other companies will probably provide similar formulations. Antioxidant and zinc supplements can also be purchased separately; however, consumers should discuss the use of these high levels of supplements with their doctors, and be certain to include copper whenever taking high levels of zinc.  Source: NEI.

2.3 Eye Examination

The leading causes of irreversible blindness--glaucoma, diabetic retinopathy, and macular degeneration--tend to come on silently, without pain or other symptoms in the earliest stages. The later an eye problem is diagnosed, the harder it becomes to treat. In some cases, any vision that has slipped away may be gone forever.

Experts say that skipping regular and thorough eye exams is chief among the barriers to early detection. It's important to have your eyes regularly checked through dilated pupils so doctors can get a good three-dimensional view of the optic nerve and retina. For a dilated exam, an eye specialist places drops in the eye to enlarge the pupils. "Without dilating the eye, it's like looking inside a room through a keyhole instead of an open door," according to George Blankenship, M.D., immediate past president of the American Academy of Ophthalmology (AAO). Source: http://www.fda.gov/fdac/features/2002/202_eyes.html

2.4 Sun Glasses

People who spend long hours on the beach or in the snow without adequate eye protection can develop photokeratitis, reversible sunburn of the cornea. This painful condition can result in temporary loss of vision. When sunlight reflects off of snow, sand and water, it further increases exposure to ultraviolet (UV) radiation. These invisible high-energy rays lie just beyond the violet end of the visible light spectrum.

Everyone is at risk for eye damage from the sun year-round. The risk is greatest from about 10 a.m. to 4 p.m. Fishermen, farmers, beach-goers, and others who spend time in the sun for extended periods are at highest risk.

UV radiation in sunlight is commonly divided into UVA and UVB, and your sunglasses should block both forms. Don't assume that you get more UV protection with pricier sunglasses or glasses with a darker tint. Look for a label that specifically states that the glasses offer 99 percent to 100 percent UV protection. You could also ask an eye-care professional to test your sunglasses if you're not sure of their level of UV protection.

Sunglasses should be dark enough to reduce glare, but not dark enough to distort colors and affect the recognition of traffic signals. Tint is mainly a matter of personal preference. For best color perception, Prevent Blindness America, a volunteer eye health and safety organization dedicated to fighting blindness and saving sight, recommends lenses that are neutral gray, amber, brown or green. People who wear contact lenses that offer UV protection should still wear sunglasses.

Children also should wear sunglasses. They shouldn't be toy sunglasses, but real sunglasses that indicate the UV-protection level just as with adults. Polycarbonate lenses are generally recommended for children because they are the most shatter-resistant. Source: http://www.fda.gov/fdac/features/2002/402_sun.html

2.5 What can you do if you have low vision?

Use special glasses, talking clocks, talking computers, raised markings on instruments, magnifiers, more lighting in the house and closed circuit television devices.

3. Refractive Errors

Refractive errors usually occur in otherwise healthy eyes. They can usually be corrected with glasses. They are caused mostly by an imperfectly shaped eyeball, cornea or lens. There are four basic types of errors:

Myopia or nearsightedness--Close objects appear sharp but those in the distance are blurred. The eyeball is longer than normal from front to back, so images focus in front of the retina instead of on it.

Hyperopia or farsightedness--Distant objects can be seen clearly but objects up close are blurred. The eyeball is shorter than normal, so images focus behind the retina.

Astigmatism--Objects are blurred at any distance. The cornea, lens, or both are shaped so that images aren't focused sharply on the retina.

Presbyopia or aging eye--The eye loses its ability to change focus due to the natural aging process. This usually occurs between ages 40 and 50.Source: http://www.fda.gov/fdac/features/2001/501_eyes.html

4. Low Vision and Eye Diseases

Vision impairment means that a person's eyesight cannot be corrected to a "normal" level.  It is a loss of vision that makes it hard or impossible to do daily tasks without specialized adaptations.  Vision impairment may be caused by a loss of visual acuity, where the eye does not see objects as clearly as usual.  It may also be caused by a loss of visual field, where the eye cannot see as wide an area as usual without moving the eyes or turning the head.

There are different ways of describing how severe a person's vision loss is.  The World Health Organization defines "low vision" as visual acuity between 20/70 and 20/400, with the best possible correction, or a visual field of 20 degrees or less.  "Blindness" is defined as a visual acuity worse than 20/400, with the best possible correction, or a visual field of 10 degrees or less.  Someone with a visual acuity of 20/70 can see at 20 feet what someone with normal sight can see at 70 feet.  Someone with a visual acuity of 20/400 can see at 20 feet what someone with normal sight can see at 400 feet.  A normal visual field is about 160-170 degrees horizontally.  

Vision impairment severity may be categorized differently for certain purposes.  In the United States, for example, we use the term "legal blindness" to indicate that a person is eligible for certain education or federal programs.  Legal blindness is defined as a visual acuity of 20/200 or worse, with the best possible correction, or a visual field of 20 degrees or less.  

Visual acuity alone cannot tell you how much a person's life will be affected by their vision loss. It is important to also assess how well a person uses the vision they have.  Two people may have the same visual acuity, but one may be able to use his or her vision better to do everyday tasks.  Most people who are "blind" have at least some usable vision that can help them move around in their environment and do things in their daily lives.  A person's functional vision can be evaluated by observing them in different settings to see how they use their vision.  A functional vision evaluation can answer questions such as these:

• Can the person scan a room to find someone or something?

• What lighting is best for the person to do different tasks?

• How does the person use his or her vision to move around in a room or outside?

Vision impairment changes how a child understands and functions in the world. Impaired vision can affect a child’s cognitive, emotional, neurological, and physical development by possibly limiting the range of experiences and the kinds of information a child is exposed to.

Nearly two-thirds of children with vision impairment also have one or more other developmental disabilities, such as mental retardation, cerebral palsy, hearing loss, or epilepsy. Children with more severe vision impairment are more likely to have additional disabilities than are children with milder vision impairment. [Read more about developmental disabilities]

The Vision Problems in the U.S. report on the prevalence of sight-threatening eye disease in Americans was released today by the National Eye Institute, in partnership with Prevent Blindness America.

"Blindness and visual impairment from most eye diseases and disorders can be reduced with early detection and treatment," U.S. Secretary of Health and Human Services Tommy G. Thompson. "That's why eye health education programs that encourage those at high risk for eye disease to have regular dilated eye exams are essential in preventing vision loss. Healthy vision is a shared responsibility among the government, health care providers, community leaders, and the public."

The director of the National Eye Institute, Paul A. Sieving, M.D., Ph.D., called for an increase in public attention to eye disease. "About one in eight Americans is 65 or older," Dr. Sieving said. "When you add declining mortality rates and population shifts, such as the 'baby boomers,' the number of older people will grow dramatically in the years ahead. Blindness and vision impairment represent not only a significant burden to those affected by sight loss, but also to the national economy as well."

The Vision Problems in the U.S. study was the result of a 2001 consensus meeting, convened by the National Eye Institute and involving many of the world's leading ophthalmic epidemiologists. Data were obtained from a systematic review of the major epidemiological studies with the cooperation of their authors. National data are broken down into state-by-state statistics.

"These are the most comprehensive data available on the prevalence of eye disease in America," said David S. Friedman, M.D., M.P.H., principal investigator of the study, and Assistant Professor of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University. "We hope this information will serve as a guide to our communities and our nation's leaders. We must comprehend the scope of eye problems in our country so that adequate resources can be devoted to research, treatment, and prevention."

A copy of the full report is available in downloadable format at www.nei.nih.gov/eyedata 

The leading causes of vision impairment and blindness in the U.S., including:

• Age-related macular degeneration (AMD), the most common cause of blindness and vision impairment in Americans aged 60 and older. More than 1.6 million Americans over age 60 have advanced AMD. (You cannot see from the center of your eye.)
• Cataract, the leading cause of blindness in the world. Cataract affects nearly 20.5 million Americans age 65 and older.(Vision is blurry.)
• Diabetic retinopathy, believed to be a leading cause of blindness in the industrialized world in people between the ages of 25 and 74. Diabetic retinopathy affects more than 5.3 million Americans age 18 and older. (There are big chunks of black pieces in your vision.)
• Glaucoma, a chronic disease that often requires life-long treatment to control. About 2.2 million Americans have been diagnosed with glaucoma, and another two million do not know they have it. (There is tunnel vision and only the center is open.)

4.1 Age-Related Macular Degeneration

Age is the greatest risk factor for AMD. Other risk factors include being

• female,
• White,
• a smoker, or
• having a family history of AMD.

The macula is in the center of the retina, the light-sensitive layer of tissue at the back of the eye. As you read, light is focused onto your macula. There, millions of cells change the light into nerve signals that tell the brain what you are seeing. This is called your central vision. With it, you are able to read, drive, and perform other activities that require fine, sharp, straight-ahead vision.

AMD occurs in two forms:

Dry AMD affects about 90 percent of those with the disease. Its cause is unknown. Slowly, the light sensitive cells in the macula break down. With less of the macula working, you may start to lose central vision in the affected eye as the years go by. Dry AMD often occurs in just one eye at first. You may get the disease later in the other eye. Doctors have no way of knowing if or when both eyes may be affected.

Wet AMD-Although only 10 percent of all people with AMD have this type, it accounts for 90 percent of all severe vision loss from the disease.

4.2 Cataracts

The lens is made mostly of water and protein. The protein is arranged to let light pass through and focus on the retina. Sometimes some of the protein clumps together. This can start to cloud small areas of the lens, blocking some light from reaching the retina and interfering with vision. This is a cataract.

A cataract is a clouding of the eye's lens that can cause vision problems. The most common type is related to aging. More than half of all Americans age 65 and older have a cataract.

Cataract can occur at any age, but you are at a higher risk after age 60. If you are over age 60, NEI recommends that you have an eye exam through dilated pupils every two years.

In its early stages, a cataract may not cause a problem. The cloudiness may affect only a small part of the lens. However, over time, the cataract may grow larger and cloud more of the lens, making it harder to see. Because less light reaches the retina, your vision may become dull and blurry. A cataract will not spread from one eye to the other, although many people develop cataracts in both eyes. Stronger lighting and eyeglasses may lessen some vision problems caused by cataracts. At a certain point, however, surgery may be needed to improve vision. Today, cataract surgery is safe and very effective. Although researchers are learning more about cataracts, no one knows for sure what causes them.

Symptoms of a cataract are:

Cloudy or blurry vision, problems with light (These can include headlights that seem too bright at night; glare from lamps or very bright sunlight; or a halo around lights.) colors that seem faded, poor night vision, double or multiple vision (this symptom often goes away as the cataract grows), frequent changes in your eyeglasses or contact lenses.

These symptoms can also be a sign of other eye problems. If you have any of these symptoms, check with your eye care professional.
When a cataract is small, you may not notice any changes in your vision. Cataracts tend to grow slowly, so vision gets worse gradually. Some people with a cataract find that their close-up vision suddenly improves, but this is temporary. Vision is likely to get worse again as the cataract grows.

What are the different types of cataract?

Age-related cataract: Most cataracts are related to aging.

Congenital cataract: Some babies are born with cataracts or develop them in childhood, often in both eyes. These cataracts may not affect vision. If they do, they may need to be removed.

Secondary cataract: Cataracts are more likely to develop in people who have certain other health problems, such as diabetes. Also, cataracts are sometimes linked to steroid use.

Traumatic cataract: Cataracts can develop soon after an eye injury, or years later.

How is a cataract detected?

To detect a cataract, an eye care professional examines the lens. A comprehensive eye examination usually includes: Visual acuity test: This eye chart test measures how well you see at various distances. Pupil dilation: The pupil is widened with eye-drops to allow your eye care professional to see more of the lens and retina and look for other eye problems. Tonometry: This is a standard test to measure fluid pressure inside the eye. Increased pressure may be a sign of glaucoma. Your eye care professional may also do other tests to learn more about the structure and health of your eye.

How is it treated?

For an early cataract, vision may improve by using different eyeglasses, magnifying lenses, or stronger lighting. If these measures dont help, surgery is the only effective treatment. This treatment involves removing the cloudy lens and replacing it with a substitute lens.

A cataract needs to be removed only when vision loss interferes with your everyday activities, such as driving, reading, or watching TV. You and your eye care professional can make that decision together. In most cases, waiting until you are ready to have cataract surgery will not harm your eye.

If you decide on surgery, your eye care professional may refer you to a specialist to remove the cataract. If you have cataracts in both eyes, the doctor will not remove them both at the same time. You will need to have each done separately. Sometimes, a cataract should be removed even if it doesn't cause problems with your vision. For example, a cataract should be removed if it prevents examination or treatment of another eye problem, such as age-related macular degeneration or diabetic retinopathy.

How is a cataract removed?

There are two primary ways to remove a cataract. Your doctor can explain the differences and help determine which is best for you:

 Phacoemulsirication., or phaco. Your doctor makes a small incision on the side of the cornea, the clear, domeshaped surface that covers the front of the eye. The doctor then inserts a tiny probe into the eye. This device emits ultrasound waves that soften and break up the cloudy center of the lens so it can be removed by suction. Most cataract surgery today is done by phaco, which is also called small incision cataract surgery.

Extracapsular surgery. Your doctor makes a slightly longer incision on the side of the cornea and removes the hard center of the lens. The remainder of the lens is then removed by suction.

In most cataract surgeries, the removed lens is replaced by an intraocular lens (10L). An IOL is a clear, artificial lens that requires no care and becomes a permanent part of your eye. With an IOL, you'll have improved vision because light will be able to pass through it to the retina. Also, you won' t feel or see the new lens. Cataract removal is one of the most common operations performed in the U.S. today. It is also one of the safest and most effective. In about 90 percent of cases, people who have cataract surgery have better vision afterward.

4.3 Diabetic Eye Disease

Taking extra care if you have diabetes or a family history of eye disease. Have an eye exam through dilated pupils every year. See an eye doctor at once if you have any loss or dimness of eyesight, eye pain, fluids coming from the eye, double vision, redness, or swelling of your eye or eyelid.

People with diabetes are at a higher risk for eye diseases, including diabetic retinopathy, glaucoma, and cataract. If you have diabetes, NEI recommends that you have an eye exam through dilated pupils at least once a year.

All people with diabetes need to get a dilated eye exam at least once a year. Diabetic eye disease refers to a group of eye problems that people with diabetes may face as a complication of this disease. All can cause severe vision loss or even blindness.

Diabetic eye disease may include: Diabetic retinopathy- damage to the blood vessels in the retina. Cataract- clouding of the eye's lens.  Glaucoma- increase in fluid pressure inside the eye that leads to optic nerve damage and loss of vision.

What is the most common diabetic eye disease?

Diabetic retinopathy. This disease is a leading cause of blindness in American adults. It is caused by changes in the blood vessels of the retina. In some people with diabetic retinopathy, retinal blood vessels may swell and leak fluid. In other people, abnormal new blood vessels grow on the surface of the retina. These changes may result in vision loss or blindness. Often there are none in the early stages of the disease. Vision may not change until the disease becomes severe. Nor is there any pain.

Blurred vision may occur when the macula the part of the retina that provides sharp, central vision swells from the leaking fluid. This condition is called macular edema. If new vessels have grown on the surface of the retina, they can bleed into the eye, blocking vision. But, even in more advanced cases, the disease may progress a long way without symptoms. That is why regular eye examinations for people with diabetes are so important.

4.4 Glaucoma

Anyone can get glaucoma, but you are at a higher risk if you are:

• Black and over age 40,
• over age 60,
• or you have a family history of glaucoma.

If you are in any of these risk groups, NEI recommends that you have an eye exam through dilated pupils every two years.

5. Eye Health Library:

Eye Disease Simulations http://www.nei.nih.gov/photo/sims/sims.htm  
Eye Problems Self-Care Guide http://familydoctor.org/flowcharts/505.html
Eye Myths http://www.preventblindness.org/eye_problems/eye_myths.html                        

http://www.nei.nih.gov

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