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Normal vision occurs when the cornea is correctly round in shape and has the correct height resulting in light rays focusing direcly on the retina. Normal vision does not mean perfect vision, rather a level of comfortable eyesight that allows for daily activities without the aid of corrective lenses.
What Is Nearsightedness or Myopia More than 70 million people in North America are nearsighted. Myopia is the medical term for nearsightedness. Myopia occurs when an eye is too long for the cornea's curvature. Light rays entering the eye do not come to a sharp focus on the retina at the back of the eye. Instead, they focus further forward, producing a blurred image.
Hyperopia is the medical term for `farsightedness.' It occurs when an eye is too short for the cornea's curvature. Light rays entering the eye focus behind the retina, and as a result a blurred image is produced.
Farsighted individuals, however, can use their focusing muscles to 'pull' the image forward onto the retina. In a young person with severe hyperopia, or once presbyopia sets in around age 45, distant objects are seen more clearly than near objects. Certain laser technologies, such as holmium lasers and hyperopic LASIK may correct this condition.
What Is Astigmatism Many patients with myopia have some degree of astigmatism, or ovalness to their cornea. It is the most common refractive condition, and occurs to some extent in most eyes. Astigmatism occurs when the cornea is shaped more like a football/rugby ball than a basketball. As a result, patients with astigmatism experience distortion or tilting of images because of unequal bending of light rays entering the eye. Patients with high degrees of astigmatism have blurred vision not only for distant objects, as with myopia, but for near objects as well.
This website has been written to help people with cataracts and their families better understand the condition. It describes the symptoms, diagnosis, and treatment of cataracts.
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. In the early stages, stronger lighting and eyeglasses may lessen 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.
What is the lens? The lens is the part of the eye that helps focus light on the retina. The retina is the eye's light sensitive layer that sends visual signals to the brain. In a normal eye, light passes through the lens and gets focused on the retina. To help produce a sharp image, the lens must remain clear. 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.
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 won't spread from one eye to the other, although many people develop cataracts in both eyes.
Although researchers are learning more about cataracts, no one knows for sure what causes them. Scientists think there may be several causes, including smoking, diabetes, and excessive exposure to sunlight.
These symptoms can also be a sign of other eye problems. If you have any of these symptoms, check with our doctors. 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.
To detect a cataract, one of our doctors examines the lens. A comprehensive eye examination usually includes:
For an early cataract, vision may improve by using different eyeglasses, magnifying lenses, or stronger lighting. If these measures don't help, surgery is the only effective treatment. This treatment involves removing the cloudy lens and replacing it with a substitute lens. You and our doctors can make that decision together. In most cases, waiting until you are ready to have cataract surgery will not harm your eye. 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.
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 over 95 percent of cases, people who have cataract surgery have better vision afterward.
Phacoemulsification, or phaco. Our doctor makes a small incision on the side of the cornea, the clear, dome-shaped 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. In most cataract surgeries, the removed lens is replaced by an intraocular lens (IOL). 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.
A week or two before surgery, our doctor will do some tests. These may include tests to measure the curve of the cornea and the size and shape of the eye. For patients who will receive an IOL, this information helps your doctor choose the right type of IOL. Also, the doctors may ask you not to eat or drink anything after midnight the morning of your surgery.
Upon arrival to Vantage Surgery Center, you will be given eye drops to dilate the pupil. The area around your eye will be washed and cleansed. The operation usually lasts 10 - 15 minutes and is almost painless. Many people choose to stay awake during surgery, while others may fall to sIeep for a short time. If you are awake, you will have an anesthetic to numb the nerves in and around your eye.
After the operation, a patch will be placed over your eye and you will rest for a while. You will be watched by our medical team for a brief period before you are released to go home that same day. Since you will not be able to drive, make sure you make arrangements for a ride.
It's normal to feel itching and mild discomfort for a while after cataract surgery. Some fluid discharge is also common, and your eye may be sensitive to light and touch. If you have discomfort, your eye care professional may suggest a pain reliever every 4-6 hours. After 1-2 days, even moderate discomfort should disappear. In most cases, healing will take about 6 weeks.
After surgery, your doctor will schedule exams to check on your progress. For a few days after surgery, you may take eyedrops or pills to help healing and control the pressure inside your eye. Ask your doctor how to use your medications, when to take them, and what effects they can have. You will also need to wear an eye shield or eyeglasses to help protect the eye. Avoid rubbing or pressing on your eye.
Problems after surgery are rare, but they can occur. These can include infection, bleeding, inflammation (pain, redness, swelling), loss of vision, or light flashes. With prompt medical attention, these problems usually can be treated successfully. When you are home, try not to bend or lift heavy objects. Bending increases pressure in the eye. You can walk, climb stairs, and do light household chores.
You can quickly return to many everyday activities, but your vision may be blurry. The healing eye needs time to adjust so that it can focus properly with the other eye, especially if the other eye has a cataract. Ask your doctor when you can resume driving. If you just received an IOL, you may notice that colors are very bright or have a blue tinge. Also, if you've been in bright sunlight, everything may be reddish for a few hours. If you see these color tinges, it is because your lens is clear and no longer cloudy. Within a few months after receiving an IOL, these colors should go away. And when you have healed, you will probably need new glasses.
Sometimes a part of the natural lens that is not removed during cataract surgery becomes cloudy and may blur your vision. This is called an after-cataract. An after- cataract can develop months or years later. Unlike a cataract, an after-cataract is treated with a laser. In a technique called YAG laser capsulotomy, your doctor uses a laser beam to make a tiny hole in the lens to let light pass through. This is a painless outpatient procedure.
There are approximately 16 million Americans who have either Type I (juvenile onset) or Type II (adult onset) diabetes. All are at risk of developing sight-threatening eye diseases that are common complications of diabetes. Although early detection and timely treatment can substantially reduce the risk of severe visual loss or blindness from diabetic eye disease, many people at risk are not having their eyes examined regularly to detect these problems before they impair vision. Increased awareness of the sight- saving benefits of annual eye examinations through dilated pupils is essential to reduce the significant social and personal costs of diabetic eye disease.
Diabetic eye disease refers to a group of sight-threatening eye problems that people with diabetes may develop as a complication of the disease. They include: Diabetic retinopathy. This disease damages blood vessels in the retina, the light-sensitive tissue at the back of the eye that translates light into electrical impulses that the brain interprets as vision.
Cataract. A cataract is an opacity of the eye's crystalline lens that results in blurring of normal vision. People with diabetes are twice as likely to develop a cataract as someone who does not have the disease. In addition, cataracts tend to develop at an earlier age in people with diabetes, around late middle age.
Glaucoma. This disease occurs when increased fluid pressure in the eye leads to progressive optic nerve damage. People with diabetes are nearly twice as likely to develop glaucoma as other adults. Cataract and glaucoma also affect many people who do not have diabetes.
Diabetic retinopathy. The NEI estimates that of the approximately 10.5 million Americans who have diagnosed diabetes, between 40-45 percent have some degree of diabetic retinopathy. Between 600,000-700,000 Americans have diabetic retinopathy severe enough to cause vision loss. As many as 24,000 people go blind from this disorder annually, making it a leading cause of blindness among working-age Americans.
It is estimated that a year of blindness costs the U.S. Government approximately $13,607 annually per person in Social Security benefits, lost income tax revenue, and health care expenditures. If Americans at risk for developing diabetic eye disease were regularly screened and treated to preserve their sight, the net annual savings to the Government would be more than $100 million.
Diabetic retinopathy is a complex disease. Although scientists understand much about the disease's natural history, they are still unclear about its specific pathological causes. There is, however, a consensus that diabetic retinopathy probably does not stem from a single retinal change. Rather, the disease may be triggered by a combination of biochemical, metabolic, and hematologic abnormalities. In people with diabetes, three metabolic and hematologic changes are suspected of being involved in the early stages of diabetic retinopathy:
Hematologic changes may cause the retinal blood vessels to constrict. These abnormalities may cause certain cells to die inside the retinal blood vessels. This leads to altered blood flow, increased blood vessel permeability, and the growth of certain blood vessel components. As a result, tiny outcroppings--called microaneurysms--may bulge from the weak blood vessel walls. The microaneurysms, which resemble tiny blisters on the blood vessels, may leak blood onto the central retina, or macula, causing an early, sight-impairing swelling of this area called macular edema. The disease enters its proliferative stage when abnormal new blood vessels begin to grow into the retina and optic disc to increase blood flow to these tissues. New blood vessels may form because of hormonal signals, i.e., growth hormone, sent to the eye. These new blood vessels are fragile and often leak blood and protein into the vitreous--the transparent gel that fills two-thirds of the inner eye--and retina, causing visual impairment.
As the disease progresses, the new blood vessels may also grow into the vitreous and cause it to detach gradually from the back of the eye. As the vitreous pulls away, it may detach the retina as well. As a result, severe visual loss or blindness will occur.
For many people with diabetic retinopathy, there are no early symptoms. There is no pain, no blurred vision, and no ocular inflammation. In fact, many people do not develop any visual impairment until the disease has advanced well into its proliferative stage. At this point, the vision that has been lost cannot be restored. However, some people in the early and advanced stages of diabetic retinopathy may notice a change in their central and/or color vision. The loss of central vision results from macular edema, which can often be effectively treated.
Because diabetic eye disease often has no early symptoms, it is detected during a comprehensive eye examination through dilated pupils. Dilation consists of the eye care professional's placing medicated drops into the eye to enlarge the pupil. By doing so, the practitioner can better examine the back of the eye for early signs of disease, such as microaneurysms, before noticeable vision loss occurs.
For example, if the eye care professional detects diabetic retinopathy early, he or she can then monitor the patient's condition and determine the best time to treat the problem, should it progress to that point. The National Eye Health Education Program--coordinated by the National Eye Institute, one of the Federal National Institutes of Health--recommends that people with diabetes undergo a comprehensive eye examination through dilated pupils at least once a year.
Laser surgery, also called photocoagulation, is now being used successfully to treat proliferative retinopathy. It is performed by aiming a narrow, high-energy beam of light through the pupil and onto the retina. The beam of light is used to make hundreds of small burns over the retinal surface that destroy the growing blood vessels. Laser surgery is also used to treat macular edema. In this procedure, however, the laser is aimed directly onto leaking blood vessels in the macula. The beam of light then seals the blood vessels to stop their sight-impairing leakage.
Current treatment guidelines are so successful that even people with proliferative retinopathy have a 90 percent chance of maintaining their vision. Current treatment guidelines call for (1) regular eye examinations through dilated pupils, (2) timely laser surgery, and (3) when needed, vitrectomy, a surgical procedure that clears hemorrhaged blood that can cloud vision from inside the eye. The Diabetes Control and Complications Trial (DCCT) showed that better control of blood sugar levels slows the onset and progression of retinopathy and lessens the need for laser surgery for severe retinopathy.
Our website is designed to help people with glaucoma and their families better understand the disease. It describes the causes, symptoms, diagnosis, and treatment of glaucoma. It is mainly about open-angle glaucoma, the most common kind in the United States. Glaucoma is a group of diseases that can lead to damage to the eye's optic nerve and result in blindness. Open-angle glaucoma, the most common form of glaucoma, affects about 3 million Americans--half of whom don't know they have it. It has no symptoms at first. But over the years it can steal your sight. With early treatment, you can often protect your eyes against serious vision.
The optic nerve is a bundle of more than 1 million nerve fibers. It connects the retina, the light-sensitive layer of tissue at the back of the eye, with the brain (see diagram). A healthy optic nerve is necessary for good vision.
In many people, increased pressure inside the eye causes glaucoma. In the front of the eye is a space called the anterior chamber. A clear fluid flows continuously in and out of this space and nourishes nearby tissues.
The fluid leaves the anterior chamber at the angle where the cornea and iris meet. When the fluid reaches the angle, it flows through a spongy meshwork, like a drain, and leaves the eye. Open-angle glaucoma gets its name because the angle that allows fluid to drain out of the anterior chamber is open. However, for unknown reasons, the fluid passes too slowly through the meshwork drain. As the fluid builds up, the pressure inside the eye rises. Unless the pressure at the front of the eye is controlled, it can damage the optic nerve and cause vision loss.
At first, open-angle glaucoma has no symptoms. Vision stays normal, and there is no pain. As glaucoma remains untreated, people may notice that although they see things clearly in front of them, they miss objects to the side and out of the corner of their eye. Without treatment, people with glaucoma may find that they suddenly have no side vision. It may seem as though they are looking through a tunnel. Over time, the remaining forward vision may decrease until there is no vision left.
Most people think that they have glaucoma if the pressure in their eye is increased. This is not always true. High pressure puts you at risk for glaucoma. It may not mean that you have the disease. Whether or not you get glaucoma depends on the level of pressure that your optic nerve can tolerate without being damaged. This level is different for each person. Although normal pressure is usually between 12-21 mm Hg, a person might have glaucoma even if the pressure is in this range. That is why an eye examination is very important.
Visual acuity: This eye chart test measures how well you see at various distances.
Visual Field: This test measures your side (peripheral) vision. It helps your eye care professional find out if you have lost side vision, a sign of glaucoma.
Pupil dilation: This examination provides your eye care professional with a better view of the optic nerve to check for signs of damage. To do this, your eye care professional places drops into the eye to dilate (widen) the pupil. After the examination, your close- up vision may remain blurred for several hours.
Tonometry: This standard test determines the fluid pressure inside the eye. There are many types of tonometry. One type uses a purple light to measure pressure. Another type is the "air puff," test, which measures the resistance of the eye to a puff of air.
Yes. Although you will never be cured of glaucoma, treatment often can control it. This makes early diagnosis and treatment important to protect your sight. Most doctors use medications for newly diagnosed glaucoma; however, new research findings show that laser surgery is a safe and effective alternative.
Medicine: Medicines are the most common early treatment for glaucoma. They come in the form of eye drops and pills. Some cause the eye to make less fluid. Others lower pressure by helping fluid drain from the eye. Glaucoma drugs may be taken several times a day. Most people have no problems. However some medicines can cause headaches or have side effects which affect other parts of the body. Drops may cause stinging, burning, and redness in the eye. Ask your eye care professional to show you how to put the drops into your eye. In addition, tell your eye care professional about other medications you may be taking before you begin glaucoma treatment. Many drugs are available to treat glaucoma. If you have problems with one medication, tell your eye care professional. Treatment using a different dosage or a new drug may be possible. You will need to use the drops and/or pills as long as they help to control your eye pressure. This is very important. Because glaucoma often has no symptoms, people may be tempted to stop or may forget to take their medicine.
Laser surgery (also called laser trabeculoplasty): Laser surgery helps fluid drain out of the eye. Although our doctors may suggest laser surgery at any time, it is often done after trying treatment with medicines. In many cases, you will need to keep taking glaucoma drugs even after laser surgery. Laser surgery is performed in an eye care professional's office or eye clinic. Before the surgery, our doctor will apply drops to numb the eye. As you sit facing the laser machine, your eye care professional will hold a special lens to your eye. A high-energy beam of light is aimed at the lens and reflected onto the meshwork inside your eye. You may see flashes of bright green or red light. The laser makes 50-100 evenly spaced burns. These burns stretch the drainage holes in the meshwork. This helps to open the holes and lets fluid drain better through them. Our doctors will check your eye pressure shortly afterward. He or she may also give you some drops to take home for any soreness or swelling inside the eye. You will need to make several follow up visits to have your pressure monitored.
Once you have had laser surgery over the entire meshwork, further laser treatment may not help. Studies show that laser surgery is very good at getting the pressure down. But its effects sometimes wear off over time. Two years after laser surgery, the pressure increases again in more than half of all patients.
Conventional surgery: The purpose of surgery is to make a new opening for the fluid to leave the eye. Although our doctors may suggest it at any time, this surgery is often done after medicine and laser surgery have failed to control your pressure. Surgery is performed in a clinic or hospital. Before the surgery, your eye care professional gives you medicine to help you relax and then small injections around the eye to make it numb. The eye care professional removes a small piece of tissue from the white (sclera) of the eye. This creates a new channel for fluid to drain from the eye. But surgery does not leave an open hole in the eye. The white of the eye is covered by a thin, clear tissue called the conjunctiva. The fluid flows through the new opening, under the conjunctiva, and drains from the eye.
You must put drops in the eye for several weeks after the operation to fight infection and swelling. (The drops will be different than the eye drops you were using before surgery.) You will also need to make frequent visits to your eye care professional. This is very important, especially in the first few weeks after surgery. In some patients, surgery is about 80 to 90 percent effective at lowering pressure. However, if the new drainage opening closes, a second operation consisting of a drainage implant with a tiny tube to help drain fluid and lower the eye presure may be needed. Conventional surgery works best if you have not had previous eye surgery, such as a cataract operation. Keep in mind that while glaucoma surgery may save remaining vision, it does not improve sight. In fact, your vision may not be as good as it was before surgery.
Like any operation, glaucoma surgery can cause side effects. These include cataract, problems with the cornea, inflammation or infection inside the eye, and swelling of blood vessels behind the eye. However, if you do have any of these problems, effective treatments are available.
Although open-angle glaucoma is the most common form, some people have other forms of the disease. In low-tension or normal-tension glaucoma, optic nerve damage and narrowed side vision occur unexpectedly in people with normal eye pressure. People with this form of the disease have the same types of treatment as open-angle glaucoma. In closed-angle glaucoma, the fluid at the front of the eye cannot reach the angle and leave the eye because the angle gets blocked by part of the iris. People with this type of glaucoma have a sudden increase in pressure. Symptoms include severe pain and nausea as well as redness of the eye and blurred vision. This is a medical emergency. The patient needs immediate treatment to improve the flow of fluid. Without treatment, the eye can become blind in as little as one or two days. Usually, prompt laser surgery can clear the blockage and protect sight.
In congenital glaucoma, children are born with defects in the angle of the eye that slow the normal drainage of fluid. Children with this problem usually have obvious symptoms such as cloudy eyes, sensitivity to light, and excessive tearing. Surgery is usually the suggested treatment, because medicines may have unknown effects in infants and be difficult to give to them. The surgery is safe and effective. If surgery is done promptly, these children usually have an excellent chance of having good vision.
Secondary glaucomas can develop as a complication of other medical conditions. They are sometimes associated with eye surgery or advanced cataracts, eye injuries, certain eye tumors, or uveitis (eye inflammation). One type, known as pigmentary glaucoma, occurs when pigment from the iris flakes off and blocks the meshwork, slowing fluid drainage. A severe form, called neovascular glaucoma, is linked to diabetes. Also, corticosteroid drugs used to treat eye inflammations and other diseases--can trigger glaucoma in a few people. Treatment is with medicines, laser surgery, or conventional surgery.
MACULAR DEGENERATION: An eye condition in which the macula is damaged, often causing loss of central vision. (Macula=sensitive area in the retina responsible for central and detail vision.)
TYPES: "Dry form" - usually progresses slowly and causes central vision loss. "Wet" form - rarer, and more severe. May progress rapidly causing significant central vision loss.
WHO GETS IT: Most common in people over 60; but can appear as early as age 40. Macular degeneration is the most common cause of severe vision loss among people over 65, and, as life expectancy increases, the disease is becoming an increasingly significant problem.
CAUSES: Not certain. No conclusive proof exists, however some scientists believe heredity may play a part, as may UV light exposure and nutrition. Studies are ongoing.
SYMPTOMS: Blurred or fuzzy vision; straight lines (such as sentences on a page or telephone poles) appear wavy; blind spot in the center of vision.
PREVENTION: Not certain. Some steps may help:
TREATMENT: "Dry" form - usually none. Low vision rehabilitation can help those with significant vision loss to maintain excellent quality of life. "Wet" form - Avastin or Lucentis injections have been shown to be benificial in some cases. In addition Laser surgery may help. Low vision rehabilitation for those with vision loss helps maximize use of existing vision.
UNPROVEN TREATMENTS: Be wary of any treatment that promises to restore vision, or cure or prevent macular degeneration. There are many so-called "miracle cures" advertised (often in magazines or on the Internet) that have not been adequately tested for safety or efficacy. These treatments may be expensive, and are generally not covered by insurance. If you are considering trying a new or untested treatment, make sure you talk to your Eye MD to ensure they are safe and won't interfere with timely and effective treatment of any eye problems.
CURRENT RESEARCH: There is a great deal of research and several major scientific studies being conducted to find the causes and develop effective treatments for all types of macular degeneration. At Vantage Eye Center our retinal specialists participate in many of the clinical studies through our affiliation with Stanford University. In addition, we have the most modern techniques available for treating macular degeneration including Avastin and Lucentis therapy.
LOW VISION REHABILITATION: Can help people who have experienced mild to severe vision loss adjust to their condition and continue to enjoy active and independent lifestyles. Rehabilitation may involve anything from adjusting the lighting in your home to learning to use low vision aids to help you read and perform daily tasks. Your Eye MD can arrange rehabilitation or refer you to organizations that can help.
SUPPORT: Adjusting to vision loss can be difficult at first. Your Eye MD may be able to recommend some support groups for people with low vision. You can support friends and family by encouraging them in their rehabilitation efforts and providing help (such as rides to appointments) when needed.
RESOURCES: Your Eye M.D is your best resource for any eye-care question or need. (Your Eye MD is a medical doctor specially trained to provide the full range of eye care, from eye exams and prescribing glasses and contacts to complex surgery for eye problems.)
Blepharitis is a very common condition meaning inflammation of the eyelids. It usually results from a problem on a small oil gland in the eyelids not secreting the oils that form part of the tears well enough.
Blepharitis can result in eye and eyelid redness, irritation, crusting and a dry or sandy feeling in the eyes. It is often found in association with dry eyes. It is usually treated in a step-wise fashion including:
It often takes weeks to notice significant improvements after starting treatment. Once improvement is noted the frequency of the treatment can often be reduced, but not stopped. If the treatment is stopped the blepharitis tends to return.