Your eyelids help protect your eyes. When you blink, your eyelids spread moisture over your eyes. Blinking also helps move dirt or other particles off the surface of the eye. You close your eyelids when you see something coming toward your eyes. This can help protect against injuries.

Like most other parts of your body, your eyelids can get infected, inflamed, or even develop cancer. There are also specific eyelid problems, including

• Eyelids that turn in or out
• Eyelids that droop
• Abnormal blinking or twitching

Treatment of eyelid problems depends on the cause.

Some eye problems are minor and don't last long. But some can lead to a permanent loss of vision.

Common eye problems include

• Refractive errors
• Cataracts - clouded lenses
• Optic nerve disorders, including glaucoma
• Retinal disorders - problems with the nerve layer at the back of the eye
• Macular degeneration - a disease that destroys sharp, central vision
• Diabetic eye problems
• Conjunctivitis - an infection also known as pinkeye

Your best defense is to have regular checkups, because eye diseases do not always have symptoms. Early detection and treatment could prevent vision loss. See an eye care professional right away if you have a sudden change in vision, if everything looks dim, or if you see flashes of light. Other symptoms that need quick attention are pain, double vision, fluid coming from the eye, and inflammation.

• Approximately 12 million people 40 years and over in the United States have vision impairment, including 1 million who are blind, 3 million who have vision impairment after correction, and 8 million who have vision impairment due to uncorrected refractive error.
• As of 2012, 4.2 million Americans aged 40 years and older suffer from uncorrectable vision impairment, out of which 1.02 million who are blind; this number is predicted to more than double by 2050 to 8.96 million due to the increasing epidemics of diabetes and other chronic diseases and our rapidly aging U.S. population.
• Approximately 6.8% of children younger than 18 years in the United States have a diagnosed eye and vision condition. Nearly 3 percent of children younger than 18 years are blind or visually impaired, defined as having trouble seeing even when wearing glasses or contact lenses.
• The National Institute for Occupational Safety and Health (NIOSH) reports that every day about 2,000 U.S. workers sustain job-related eye injuries that require medical treatment. However, safety experts and eye doctors believe the right eye protection can lessen the severity or even prevent 90 percent of these eye injuries.
• An estimated 93 million adults in the United States are at high risk for serious vision loss, but only half visited an eye doctor in the past 12 months.
• The annual economic impact of major vision problems among the adult population 40 years and older is more than $145 billion.
• Vision disability is one of the top 10 disabilities among adults 18 years and older and one of the most prevalent disabling conditions among children.
• Early detection and timely treatment of eye conditions such as diabetic retinopathy has been found to be efficacious and cost effective.
• 90% of blindness caused by diabetes is preventable..
• Vision loss causes a substantial social and economic toll for millions of people including significant suffering, disability, loss of productivity, and diminished quality of life.
• National and state data show that more than half of adult Americans who did not seek eye care are due to lack of awareness or costs; which often exacerbated by lack of adequate health insurance.
• More than 70% of survey respondents from National Eye Health Education Program (NEHEP) 2005 Public Knowledge, Attitudes, and Practices survey consider that the loss of their eyesight would have the greatest impact on their day-to-day life; however, less than 11% knew that there are no early warning signs of glaucoma and diabetic retinopathy.

Amblyopia, or "lazy eye," is the most common cause of visual impairment in children. It happens when an eye fails to work properly with the brain. The eye may look normal, but the brain favors the other eye. In some cases, it can affect both eyes. Causes include

• Strabismus - a disorder in which the two eyes don't line up in the same direction
• Refractive error in an eye - when one eye cannot focus as well as the other, because of a problem with its shape. This includes nearsightedness, farsightedness, and astigmatism.
• Cataract - a clouding in the lens of the eye

It can be hard to diagnose amblyopia. It is often found during a routine vision exam.

Treatment for amblyopia forces the child to use the eye with weaker vision. There are two common ways to do this. One is to have the child wear a patch over the good eye for several hours each day, over a number of weeks to months. The other is with eye drops that temporarily blur vision. Each day, the child gets a drop of a drug called atropine in the stronger eye. It is also sometimes necessary to treat the underlying cause. This could include glasses or surgery.

A cataract is a clouding of the lens in your eye. It affects your vision. Cataracts are very common in older people. By age 80, more than half of all Americans either have a cataract or have had cataract surgery.

A cataract can occur in either or both eyes. It cannot spread from one eye to the other. Common symptoms are

• Blurry vision
• Colors that seem faded
• Glare - headlights, lamps or sunlight may seem too bright. You may also see a halo around lights.
• Not being able to see well at night
• Double vision
• Frequent prescription changes in your eye wear

Cataracts usually develop slowly. New glasses, brighter lighting, anti-glare sunglasses or magnifying lenses can help at first. Surgery is also an option. It involves removing the cloudy lens and replacing it with an artificial lens. Wearing sunglasses and a hat with a brim to block ultraviolet sunlight may help to delay cataracts.

Most of us see our world in color. We enjoy looking at a lush green lawn or a red rose in full bloom. If you have a color vision defect, you may see these colors differently than most people.

There are three main kinds of color vision defects. Red-green color vision defects are the most common. This type occurs in men more than in women. The other major types are blue-yellow color vision defects and a complete absence of color vision.

Most of the time, color blindness is genetic. There is no treatment, but most people adjust and the condition doesn't limit their activities.

Your cornea is the outermost layer of your eye. It is clear and shaped like a dome. The cornea helps to shield the rest of the eye from germs, dust, and other harmful matter. It also helps your eye to focus. If you wear contact lenses, they float on top of your corneas.

Problems with the cornea include

• Refractive errors
• Allergies
• Infections
• Injuries
• Dystrophies - conditions in which parts of the cornea lose clarity due to a buildup of cloudy material

Treatments of corneal disorders include medicines, corneal transplantation, and corneal laser surgery.

If you have diabetes, your blood glucose, or blood sugar, levels are too high. Over time, this can damage your eyes. The most common problem is diabetic retinopathy. It is a leading cause of blindness in American adults.

Your retina is the light-sensitive tissue at the back of your eye. You need a healthy retina to see clearly. Diabetic retinopathy damages the tiny blood vessels inside your retina.

You may not notice it at first. Symptoms can include

• Blurry or double vision
• Rings, flashing lights, or blank spots
• Dark or floating spots
• Pain or pressure in one or both of your eyes
• Trouble seeing things out of the corners of your eyes

Treatment often includes laser treatment or surgery, with follow-up care.

Two other eye problems can happen to people with diabetes. A cataract is a cloud over the lens of your eye. Surgery helps you see clearly again. Glaucoma happens when pressure builds up in the eye, damaging the main nerve. Eye drops or surgery can help.

If you have diabetes, you should have a complete eye exam every year. Finding and treating problems early may save your vision.

Cancer of the eye is uncommon. It can affect the outer parts of the eye, such as the eyelid, which are made up of muscles, skin and nerves. If the cancer starts inside the eyeball it's called intraocular cancer. The most common intraocular cancers in adults are melanoma and lymphoma. The most common eye cancer in children is retinoblastoma, which starts in the cells of the retina. Cancer can also spread to the eye from other parts of the body.

Treatment for eye cancer varies by the type and by how advanced it is. It may include surgery, radiation therapy, freezing or heat therapy, or laser therapy.

Your eyes are an important part of your health. Most people rely on their eyes to see and make sense of the world around them. But some eye diseases can lead to vision loss, so it is important to identify and treat eye diseases as early as possible. You should get your eyes checked as often as your health care provider recommends it, or if you have any new vision problems. And just as it is important to keep your body healthy, you also need to keep your eyes healthy.

Eye Care Tips

There are things you can do to help keep your eyes healthy and make sure you are seeing your best:

• Eat a healthy, balanced diet. Your diet should include plenty or fruits and vegetables, especially deep yellow and green leafy vegetables. Eating fish high in omega-3 fatty acids, such as salmon, tuna, and halibut can also help your eyes.
• Maintain a healthy weight. Being overweight or having obesity increases your risk of developing diabetes. Having diabetes puts you at higher risk of getting diabetic retinopathy or glaucoma.
• Get regular exercise. Exercise may help to prevent or control diabetes, high blood pressure, and high cholesterol. These diseases can lead to some eye or vision problems. So if you exercise regularly, you can lower your risk of getting these eye and vision problems.
• Wear sunglasses. Sun exposure can damage your eyes and raise your risk of cataracts and age-related macular degeneration. Protect your eyes by using sunglasses that block out 99 to 100 percent of both UV-A and UV-B radiation.
• Wear protective eye wear. To prevent eye injuries, you need eye protection when playing certain sports, working in jobs such as factory work and construction, and doing repairs or projects in your home.
• Avoid smoking. Smoking increases the risk of developing age-related eye diseases such as macular degeneration and cataracts and can damage the optic nerve.
• Know your family medical history. Some eye diseases are inherited, so it is important to find out whether anyone in your family has had them. This can help you determine if you are at higher risk of developing an eye disease.
• Know your other risk factors. As you get older, you are at higher risk of developing age-related eye diseases and conditions. It is important to know you risk factors because you may be able to lower your risk by changing some behaviors.
• If you wear contacts, take steps to prevent eye infections. Wash your hands well before you put in or take out your contact lenses. Also follow the instructions on how to properly clean them, and replace them when needed.
• Give your eyes a rest. If you spend a lot of time using a computer, you can forget to blink your eyes and your eyes can get tired. To reduce eyestrain, try the 20-20-20 rule: Every 20 minutes, look away about 20 feet in front of you for 20 seconds.

Eye Tests and Exams

Everyone needs to have their eyesight tested to check for vision and eye problems. Children usually have vision screening in school or at their health care provider's office during a checkup. Adults may also get vision screenings during their checkups. But many adults need more than a vision screening. They need a comprehensive dilated eye exam.

Getting comprehensive dilated eye exams is especially important because some eye diseases may not have warning signs. The exams are the only way to detect these diseases in their early stages, when they are easier to treat.

The exam includes several tests:

• A visual field test to measure your side (peripheral) vision. A loss of peripheral vision may be a sign of glaucoma.
• A visual acuity test, where you read an eye chart about 20 feet away, to check on how well you see at various distances
• Tonometry, which measures your eye's interior pressure. It helps to detect glaucoma.
• Dilation, which involves getting eye drops that dilate (widen) your pupils. This allows more light to enter the eye. Your eye care provider examines your eyes using a special magnifying lens. This provides a clear view of important tissues at the back of your eye, including the retina, macula, and optic nerve.

If you have a refractive error and are going to need glasses or contacts, then you will also have a refraction test. When you have this test, you look through a device that has lenses of different strengths to help your eye care professional figure out which lenses will give you the clearest vision.

At what age you should start getting these exams and how often you need them depends on many factors. They include your age, race, and overall health. For example, if you are African American, you are at higher risk of glaucoma and you need to start getting the exams earlier. If you have diabetes, you should get an exam every year. Check with your health care provider about if and when you need these exams.

Your eyes can get infections from bacteria, fungi, or viruses. Eye infections can occur in different parts of the eye and can affect just one eye or both. Two common eye infections are

• Conjunctivitis - also known as pinkeye. Conjunctivitis is often due to an infection. Children frequently get it, and it is very contagious.
• Stye - a bump on the eyelid that happens when bacteria from your skin get into the hair follicle of an eyelash.

Symptoms of eye infections may include redness, itching, swelling, discharge, pain, or problems with vision. Treatment depends on the cause of the infection and may include compresses, eye drops, creams, or antibiotics.

The structure of your face helps protect your eyes from injury. Still, injuries can damage your eye, sometimes severely enough that you could lose your vision. Most eye injuries are preventable. If you play sports or work in certain jobs, you may need protection.

The most common type of injury happens when something irritates the outer surface of your eye. Certain jobs such as industrial jobs or hobbies such as carpentry make this type of injury more likely. It's also more likely if you wear contact lenses.

Chemicals or heat can burn your eyes. With chemicals, the pain may cause you to close your eyes. This traps the irritant next to the eye and may cause more damage. You should wash out your eye right away while you wait for medical help.

When you look at an object, you're using several muscles to move both eyes to focus on it. If you have a problem with the muscles, the eyes don't work properly.

There are many kinds of eye movement disorders. Two common ones are

• Strabismus - a disorder in which the two eyes don't line up in the same direction. This results in "crossed eyes" or "walleye."
• Nystagmus - fast, uncontrollable movements of the eyes, sometimes called "dancing eyes"

Some eye movement disorders are present at birth. Others develop over time and may be associated with other problems, such as injuries. Treatments include glasses, patches, eye muscle exercises, and surgery. There is no cure for some kinds of eye movement disorders, such as most kinds of nystagmus.

Eye wear protects or corrects your vision. Examples are

• Sunglasses
• Safety goggles
• Glasses (also called eyeglasses)
• Contact lenses

If you need corrective lenses, you may be able to choose between contacts or glasses. Either usually requires a prescription. Almost anyone can wear glasses. Contact lenses require more careful handling.

Many jobs and some sports carry a risk of eye injury. Thousands of children and adults get eye injuries every year. Most are preventable with proper eye protection. Everyone is at risk for eye damage from the sun year-round. It's important to regularly use sunglasses that block out at least 99% of UV rays.

Glaucoma is a group of diseases that can damage the eye's optic nerve. It is a leading cause of blindness in the United States. It usually happens when the fluid pressure inside the eyes slowly rises, damaging the optic nerve. Often there are no symptoms at first. Without treatment, people with glaucoma will slowly lose their peripheral, or side vision. They seem to be looking through a tunnel. Over time, straight-ahead vision may decrease until no vision remains.

A comprehensive eye exam can tell if you have glaucoma. People at risk should get eye exams at least every two years. They include

• African Americans over age 40
• People over age 60, especially Mexican Americans
• People with a family history of glaucoma

There is no cure, but glaucoma can usually be controlled. Early treatment can help protect your eyes against vision loss. Treatments usually include prescription eyedrops and/or surgery.

Macular degeneration, or age-related macular degeneration (AMD), is a leading cause of vision loss in Americans 60 and older. It is a disease that destroys your sharp, central vision. You need central vision to see objects clearly and to do tasks such as reading and driving.

AMD affects the macula, the part of the eye that allows you to see fine detail. It does not hurt, but it causes cells in the macula to die. There are two types: wet and dry. Wet AMD happens when abnormal blood vessels grow under the macula. These new blood vessels often leak blood and fluid. Wet AMD damages the macula quickly. Blurred vision is a common early symptom. Dry AMD happens when the light-sensitive cells in the macula slowly break down. Your gradually lose your central vision. A common early symptom is that straight lines appear crooked.

Regular comprehensive eye exams can detect macular degeneration before the disease causes vision loss. Treatment can slow vision loss. It does not restore vision.