Eye Disease Library
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Age related macular degeneration or ARMD is the most common cause of irreversible vision loss for people over the age of 55. It is estimated that 2.5 million people in developed countries will suffer visual loss from this disorder and that there are approximately 200,000 new cases diagnosed every year.
Macular degeneration is most common in people over the age of 65 but there have been some cases affecting people as young as their 40s and 50s. Symptoms include blurry or fuzzy vision, straight lines like telephone poles and sides of buildings appear wavy and a dark or empty area may appear in the center of vision.
What is the Macula? The macula is the small portion of the retina located at the center of this light sensitive lining at the back of the eye. Light rays from objects that we are looking at come to a focus on the retina and are converted into electrical impulses that are then sent to the brain. The macula is responsible for sharp straight-ahead vision necessary for functions such as reading, driving a car and recognizing faces.
The effect of this disease can range from mild vision loss to central blindness. That is, blindness "straight ahead" but with normal peripheral vision from the non-macular part of the retina which is undamaged by the disease.
Two types of Macular Degeneration Ninety percent of ARMD is of the "atrophic" or "dry" variety. It is characterized by a thinning of the macular tissue and the development of small deposits on the retina called drusen. Dry ARMD develops slowly and usually causes mild visual loss. The main symptom is often a dimming of vision when reading.
The second form of ARMD is called "exudative" or "wet" because of the abnormal growth of new blood vessels under the macula where they leak and eventually create a large blind spot in the central vision. This form of the disease is of much greater threat to vision than the more common dry type.
What are the causes of ARMD? Unfortunately, the cause of this eye condition is not fully understood but it is associated with the aging process. As we age, we become more susceptible to numerous degenerative processes like arthritis, heart conditions, cancer, cataracts and macular degeneration. These conditions may be caused by the body's overproduction of free radicals.
During the metabolic process, oxygen atoms with an extra electron are released. These extra electrons are quite destructive and cause cellular damage, alter DNA, and are thought to be at least partially responsible for many of the degenerative diseases mentioned above. The production of these free radicals is normal during metabolism but the body produces its own "anti-oxidants" to neutralize them.
Some of the vitamins in the food we eat also have anti-oxidant properties. These are vitamins A, C, E and beta-carotene. Unfortunately, smoking, poor nutrition and other lifestyle factors result in the body producing too many free radicals. For this reason, lifestyle factors may contribute to the risk of ARMD.
There is some evidence to suggest that ARMD has a genetic basis, as the condition tends to run in families. The exact nature of this familial tendency, however, has not been clarified. It has been suggested from twin studies that there is a defect in the genes responsible for the integrity and health of the retina.
Exposure to certain types of light may also play a role. Studies performed on fishermen in the Chesapeake Bay suggest that long-term exposure to ultraviolet light from the sun may increase the risk of ARMD and other eye conditions such as the development of cataracts
It has also been hypothesized that hyperopia or farsightedness may also play a role in the development of the disease. It is thought that the shortening of the eye in hyperopia may cause changes in the membrane below the macula and in its blood vessels.
In the dry form of the disease, some form of inflammation may also be a factor although what causes the inflammation is not known.
How is it treated? lthough researchers are spending a great deal of time investigating the cause and treatment of ARMD, there is no real cure available. The goal of current treatment efforts is to attempt to stabilize the condition.
For the more severe wet form of the disease, doctors have tried laser photocoagulation. This treatment, however, is not without dangers and is only beneficial in the very early stages of the condition, which is why early detection is so important. This technique involves directing a beam of laser light at the abnormal blood vessels in order to destroy them and prevent their leaking. Provided that the blood vessels have not grown under the macula, this treatment can be helpful in arresting the progress of the disease. If the blood vessels are already under the macula, the laser may cause scarring and permanent vision loss.
Several new treatments are under development and scientific evaluation.
A new type of treatment called photodynamic shows promise. A drug, injected into the arm travels to the affected eye and is then exposed to a non-thermal red light. This light activates the drug to close and seal off the abnormal blood vessels. The entire treatment only takes about 30 minutes and requires no anesthetic.
Treatment using proton beams, which release power at predetermined target site and depth, has also been experimentally tested for treatment of wet-ARMD.
Are Vitamins and Nutrition Useful? No treatment exists for the dry form but many doctors are convinced that a combination of specific vitamins and minerals helps slow the progression of the disease. This has yet to be confirmed scientifically but there are valid reasons for attempting this therapy. Anti-oxidant vitamins may help to neutralize the free radicals that are associated with this degenerative process. Zinc, one of the most common trace minerals in our body, is highly concentrated in the retina and surrounding tissues and is a requirement for chemical reactions in the retina.
Fat-soluble anti-oxidant vitamins like vitamin A and vitamin E are stored in the body and can increase to toxic levels if over used and zinc may interfere with other trace minerals like copper. Caution should therefore be exercised in the use of vitamins and minerals.
If your eyelid rims are red and irritated, if they burn and itch or if you've noticed an oily discharge or scaly skin around them, you may have an inflammatory problem called "blepharitis". Some people describe it as "psoriasis of the eyelids".
Blepharitis may be either of two main types or a combination of them.
Seborrheic blepharitis Characterized by an excessive discharge of oil/grease from the skin around the eyelids. It is usually accompanied by similarly greasy hair and skin.
Staphylococcal blepharitis A bacterial infection. It is more likely to result in infective eyelid conditions, such as styes.
What are the treatments? To treat seborrheic blepharitis, keep the lid edges and surrounding skin clean by regularly scrubbing the area with a mild soap. Medicated pads specifically designed for this are also available. For staphylococcal blepharitis, ointments containing antibiotics and sulfonamides should be applied to the edges of the eyelids with a cotton ball.
While over-the-counter treatments for blepharitis are available, it is advisable to seek professional help the first time you experience the condition. If you have had blepharitis before and had experience with its treatment, using the over-the-counter ointments may be adequate. But, whether you have had the condition before or not, if the blepharitis is infectious, you should get appropriate treatment as soon as possible to reduce the risk of having the infection spread and cause more serious conditions.
Red, watery eyes, inflamed lids, blurred vision and a sandy or scratchy feeling in the eyes may indicate that you have conjunctivitis. Pus-like or watery discharge around the eyelids may indicate an infectious form of the disease, commonly known as "pink eye."
Conjunctivitis is an inflammation or infection of the conjunctiva, a thin, transparent layer covering the surface of the inner eyelid and the front of the eye. It affects people of all ages.
What causes conjunctivitis? The three main types of conjunctivitis are infectious, allergic and chemical. The infectious form, commonly known as "pink eye," is caused by a contagious virus or bacteria. Your body's allergies to pollen, cosmetics, animals or fabrics often bring on allergic conjunctivitis. Irritants like air pollution, noxious fumes and chlorine in swimming pools may produce the chemical form.
It is important to prevent spreading conjunctivitis. If contagious, measures can be taken to prevent spreading conjunctivitis to others.
- Keep your hands away from your eyes;
- Thoroughly wash hands before and after applying eye medications;
- Do not share towels, washcloths, cosmetics or eyedrops with others;
- Seek treatment promptly.
Small children, who may forget these precautions, should be kept away from school, camp and the swimming pool until the condition is cured.
Certain forms of conjunctivitis can develop into a serious condition that may harm your vision. Therefore, it is important to have conjunctivitis diagnosed and treated quickly.
How is infectious conjunctivitis treated? Infectious conjunctivitis, caused by bacteria, is usually treated with antibiotic eye drops and/or ointment. Other infectious forms, caused by viruses, can't be treated with antibiotics and must be fought off by your body's immune system. On occasions antibiotics may be prescribed to prevent secondary bacterial infections from developing.
How are the allergic and chemical forms of conjunctivitis treated? The ideal treatment for both forms is to remove the cause of the allergy or irritation. For instance, avoid contact with any animal if it causes an allergic reaction. Wear swimming goggles if chlorinated water irritates your eyes. In cases where these measures won't work, prescription and over-the-counter eye drops are available to help relieve the discomfort.
Diabetes, a disease that prevents your body from making or using insulin to break down sugar in your bloodstream, can affect your eyes and your vision.
Fluctuating or blurring of vision, intermittent double vision, loss of peripheral vision and flashes and floaters within the eyes may be symptoms related to diabetes. Sometimes the early signs of diabetes are detected during a thorough eye examination.
Diabetes can cause changes in nearsightedness and farsightedness and lead to premature presbyopia (the inability to focus on close objects). It can result in cataracts, glaucoma, a lack of eye muscle coordination (strabismus) and decreased corneal sensitivity. The most serious eye problem associated with diabetes is diabetic retinopathy, which, if not controlled, can lead to blindness.
What is retinopathy? Diabetic retinopathy occurs when there is a weakening or swelling of the tiny blood vessels in the retina of your eye, resulting in blood leakage, the growth of new blood vessels and other changes
Can vision loss from diabetes be prevented? Yes, in a routine eye examination, your eye care practitioner can diagnose potential vision-threatening changes in your eyes that may be treated to prevent blindness. However, once damage has occurred, the effects are usually permanent. It is important to control your diabetes as much as possible to minimize the risk of developing retinopathy.
How is diabetic retinopathy treated? In the early stages, diabetic retinopathy can be treated with laser therapy. A bright beam of light is focused on the retina, causing a burn that seals off leaking blood vessels. In other cases, surgery inside the eye may be necessary. Early detection of diabetic retinopathy is crucial. It is routinely screened for in an eye examination.
Are there risk factors for developing retinopathy? Several factors that increase the risk of developing retinopathy include smoking, high blood pressure, excessive alcohol intake and pregnancy.
How can diabetes-related eye problems be prevented? Diabetes-related eye problems can be prevented by monitoring and maintaining control of your diabetes. See your physician regularly and follow instructions about diet, exercise and medication. A thorough eye examination when first diagnosed as a diabetic, at least annually thereafter, is recommended.
If your eyes sting, itch or burn, you may be experiencing the common signs of "dry eye." A feeling of something foreign within the eye or general discomfort may also signal dry eye.
What is dry eye? Dry eye describes eyes that do not produce enough tears. The natural tears that your eyes produce are composed of three layers:
- The outer oily layer, which prevents or slows evaporation of the tear film;
- The middle watery layer; which moisturizes and nourishes the front surface of the eye;
- The inner mucus layer, which helps maintain a stable tear film.
Dry eye may occur because the volume of tears produced is inadequate (we all produce fewer tears as we get older, and in some cases this can lead to dry eye symptoms). It may result because the composition of the tears has changed so that they are unstable and evaporate more quickly.
What causes dry eye? Dry eye symptoms can result from the normal aging process. Exposure to environmental conditions, as well as medications, such as antihistamines, oral contraceptives or anti-depressants, can contribute to the symptoms of dry eye. Or, dry eye can result from chemical or thermal burns to the eye. Dry eye may also be symptomatic of general health problems or other diseases. For example, people with arthritis are more prone to dry eye.
Will dry eye harm my eyes? If untreated, it can. Excessive dry eye can damage tissue and possibly scar the cornea at the front of your eye, impairing vision. Dry eye can make contact lens wear more difficult since tears may be inadequate to keep the lenses wet and lubricated. This can lead to irritation and a greater chance of eye infection. Therefore, it is important to follow the recommended treatment plan.
How is it diagnosed? During the examination, you will be asked about your general health, use of medications, and work and home environments to determine factors, which may be contributing to dry eye symptoms. This information will help decide whether to perform specific dry eye tests.
To test for dry eye, diagnostic instruments that allow a highly magnified view of your eyes or small strips of paper or thread and special dyes to assess the quantity and quality of the tears may also be used.
How is it treated? Dry eye cannot be cured, but your eyes' sensitivity can be lessened and measures taken so your eyes remain healthy. The most frequent method of treatment is the use of artificial tears or tear substitutes. For more severe dry eye, ointment can be used, especially at bedtime. In some cases, small plugs may be inserted in the corner of the eyelids to slow drainage and loss of tears.
To keep dry eye symptoms in check, you and your optometrist need to work together. If you have increased dryness or redness that is not relieved by the prescribed treatment, let us know as soon as possible.
The most scary thing about glaucoma is that it can steal your vision gradually and without your noticing. The best defense against glaucoma is a regular eye examination. Glaucoma most often strikes people over age 50. But it is recommended that during adult life everyone be tested at least every two years.
Some people with glaucoma do experience symptoms, but symptoms vary depending on the type of glaucoma.
Primary open-angle glaucoma By far the most common type, primary open-angle glaucoma develops gradually and painlessly. Since there are no early warning signs, it can slowly destroy your vision without your knowing it. The first indication may only occur after some considerable vision loss.
Acute angle-closure glaucoma This results from a sudden blockage of the drainage channels within your eye, causes a rapid build-up of pressure inside your eye accompanied by blurred vision, the appearance of colored rings around lights and sometimes extreme pain or redness in the eyes.
What is glaucoma? The build-up of pressure inside your eye leads to glaucoma. Aqueous fluid, which fills the space at the front of the eye just behind the cornea, is made behind the iris (the colored part of the eye) in the ciliary body. It flows through the pupil (the dark hole in the center of the iris), and drains from the 'anterior chamber angle,' which is the junction between the edge of the iris and the cornea. If this outflow of liquid is impaired at all, there is a build-up of pressure inside the eye that damages the optic nerve, which carries visual images to the brain. The result is a loss of peripheral vision. Thus, while glaucoma sufferers may be able to read the smallest line on the vision test, they may find it difficult to move around without bumping into things or to see moving objects to the side.
What causes glaucoma? Some causes are known, others are not. Causes differ depending on the type of glaucoma. The exact cause of open-angle glaucoma, where the drainage channels for the aqueous appear to be open and clear, is not known. Closed-angle glaucoma can occur when the pupil dilates or gets bigger and bunches the iris up around its edge, blocking the drainage channel. An injury, infection or tumor in or around the eye can also cause internal eye pressure to rise either by blocking drainage or displacing tissues and liquid within the eye. A mature cataract also can push the iris forward to block the drainage 'angle' between the iris and the cornea. Glaucoma can occur secondarily to a number of other conditions, such as diabetes, or as a result of some medications for other conditions.
Who gets glaucoma? Glaucoma most frequently occurs after age 40, but can occur at any age.
If you're of African heritage, you are more likely to develop open-angle glaucoma — and at an earlier age — than if you're Caucasian. Asians are more likely to develop narrow-angle glaucoma.
You have a higher risk of developing glaucoma if a close family member has it or if you have high blood pressure or high blood sugar (diabetes). There is also a greater tendency for glaucoma to develop in individuals who are nearsighted. Those at heightened risk for glaucoma should have their eyes checked at least once a year.
Why is glaucoma harmful to vision? The optic nerve, located at the back of the eye, carries visual information to the brain. As the fibers that make up the optic nerve are damaged by glaucoma, the amount and quality of information sent to the brain decreases and a loss of vision occurs.
Will I go blind from glaucoma? If diagnosed at an early stage, glaucoma can be controlled and little or no further vision loss should occur. If left untreated, side awareness (peripheral vision) and central vision will be destroyed and blindness may occur.
How is glaucoma detected? Tests for glaucoma are part of a comprehensive eye examination. A simple and painless procedure called tonometry measures the internal pressure of your eye. Ophthalmoscopy examines the back of the eye to observe the health of the optic nerve. A visual field test, a very sensitive test that checks for the development of abnormal blind spots, may also be completed.
How is glaucoma treated? Glaucoma is usually treated with prescription eye drops and medicines. In some cases, surgery may be required to improve drainage. The goal of the treatment is to prevent loss of vision by lowering the pressure in the eye.
Will my vision be restored after treatment? Unfortunately, any vision loss as a result of glaucoma is permanent and cannot be restored. This is why regular eye examinations are important.
Glaucoma cannot be prevented, but early detection and treatment can control glaucoma and reduce the chances of damage to the eye and a loss of sight.
A small area of redness and pain on the margin of your eyelid may indicate that you have a stye, known in medical terms as an external hordeolum. A stye is a blocked gland at the edge of the lid that has become infected by bacteria, usually Staphylococcus aureus.
The area of redness and pain will eventually form a 'point'. Until this occurs, warm compresses should be applied to the area for 15 minutes three-to-four times a day. The compresses should be followed by the application of sulphonamide or antibiotic ointment to the stye, available by prescription. Check with your eye care practitioner.
Once the stye has 'pointed', it can usually be expressed (squeezed gently to empty its contents), after which the lids should be cleaned. Treatment with the ointment should be continued until symptoms have cleared. Sometimes it is necessary for the stye to be lanced to assist with expression.