HealthyCanada.com

Overview

Blindness is the partial or total loss of vision in one or both eyes. It is one of the most feared disabilities. It is also one of the most preventable. Still more than 600-thousand Canadians have significant sight loss that affects their day to day activities and with an aging population that number is expected to double over the next 2 decades.

Symptoms

Symptoms vary according to the underlying cause but may include:

Seeing a black curtain or wall. This could be a result of retinal detachment and should be considered a medical emergency.

Loss of side (peripheral) vision. This usually develops gradually and may indicate damage to your optic nerve from diseases such as glaucoma or optic atrophy. Schedule regular visits to your eye doctor to make sure your eye is examined under lighting where your optic nerve can be observed and assessed.

Loss of straight-ahead (central) vision. This condition too can develop over many years from a very common and serious disease among the elderly called age-related macular degeneration. This disease occurs with abnormal growth of blood vessels on a portion of the inner back of your eye (retina) where the macula is located. Scarring and permanent vision loss can result. Again you should report symptoms as soon as possible so that efforts can be made to preserve any remaining vision.

Persistent eye redness and irritation. Many conditions can be responsible for these symptoms ranging from allergies to far more serious infections that can result from wearing contact lenses. Untreated eye infections may result in permanent vision loss. When in doubt see your eye doctor.

Abrupt onset of vision problems. Some vision symptoms especially when they occur suddenly may signal an emergency. Symptoms may include blurred vision light sensitivity unexplained loss of visual clarity and sudden inability to perceive colors and/or contrast. Some vision disturbances may also be related to an underlying health problem not directly related to the eye. As always see your eye doctor.

Causes

The most common causes of blindness in Canada are:

Diabetic retinopathy - a complication of diabetes that results from damage to the small blood vessels in the eye. Given the increase in the incidence of diabetes in Canada this devastating ocular disease will increase significantly over the next decade.

Age-related macular degeneration (AMD) - the most common cause of blindness and vision impairment in Canadians aged 60 and older. Recent surveys estimate that nearly one million Canadians are currently affected with AMD and as Canadians age this number is growing at a rate of 77000 per year.

Cataracts - the leading cause of blindness in the world. Approximately 244766 cataract operations were performed in Canada in the year 2001. Cataract surgery was the most common surgical procedure performed in North America over the last decade.

Glaucoma - a chronic disease that requires life-long treatment. At least 300000 Canadians are affected with 50% of them unaware of their disease.

Treatment

If you experience sudden partial or complete loss of vision in one or both eyes you should call 911 or have someone drive you to the nearest hospital emergency department. Most serious forms of vision loss are painless but the absence of pain in no way diminishes the urgent need to get medical care. If you notice any changes in your vision tell your doctor. He/she can refer you to an optometrist or ophthalmologist. Many forms of vision loss can be successfully treated if they are dealt with immediately.

Treatment depends on the underlying cause of blindness.

Diabetic retinopathy

During the first three stages of diabetic retinopathy treatment is generally not needed unless you have macular edema. To prevent progression of diabetic retinopathy people with diabetes should control their levels of blood sugar blood pressure and blood cholesterol.

Proliferative retinopathy is treated with scatter laser surgery. This procedure helps to shrink the abnormal blood vessels. The doctor places 1000 to 2000 laser burns in the areas of the retina away from the macula causing the abnormal blood vessels to shrink. Because a high number of laser burns are necessary two or more sessions usually are required to complete treatment. Although you may notice some loss of your side vision scatter laser treatment can save the rest of your sight. Scatter laser treatment may slightly reduce your color vision and night vision.

Scatter laser treatment works better before the fragile new blood vessels have started to bleed. That is why it is important to have regular comprehensive dilated eye exams. Even if bleeding has started scatter laser treatment may still be possible depending on the amount of bleeding.

If the bleeding is severe you may need a surgical procedure called a vitrectomy. During a vitrectomy blood is removed from the centre of the eye.

Age-related macular degeneration (AMD)

Once dry AMD reaches the advanced stage no form of treatment can prevent vision loss. However treatment can delay and possibly prevent intermediate AMD from progressing to the advanced stage in which vision loss occurs. Studies have shown that taking a specific high-dose formulation of antioxidants and zinc significantly reduces the risk of advanced AMD and its associated vision loss.

Wet AMD can be treated with laser surgery photodynamic therapy and injections of medicine into the eye. None of these treatments is a cure for wet AMD. Each treatment may slow the rate of vision decline or stop further vision loss but the disease and loss of vision may progress despite treatment.

Cataracts

The symptoms of early cataract may be improved with new eyeglasses brighter lighting anti-glare sunglasses or magnifying lenses. If these measures do not help surgery is the only effective treatment. Surgery involves removing the cloudy lens and replacing it with an artificial 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 this decision together. Once you understand the benefits and risks of surgery you can make an informed decision about whether cataract surgery is right for you. In most cases delaying cataract surgery will not cause long-term damage to your eye or make the surgery more difficult. You do not have to rush into surgery.

Sometimes a cataract should be removed even if it does not 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.

If you choose surgery your eye care professional may refer you to a specialist to remove the cataract.

If you have cataracts in both eyes that require surgery the surgery will be performed on each eye at separate times usually four to eight weeks apart.

Glaucoma

Immediate treatment for early stage open-angle glaucoma can delay progression of the disease. That's why early diagnosis is very important.

Glaucoma treatments include medicines laser trabeculoplasty conventional surgery or a combination of any of these. While these treatments may save remaining vision they do not improve sight already lost from glaucoma.

Medicines. Medicines in the form of eyedrops or pills are the most common early treatment for glaucoma. Some medicines cause the eye to make less fluid. Others lower pressure by helping fluid drain from the eye.

Before you begin glaucoma treatment tell your eye care professional about other medicines you may be taking. Sometimes the drops can interfere with the way other medicines work.

Glaucoma medicines may be taken several times a day. Most people have no problems. However some medicines can cause headaches or other side effects. For example drops may cause stinging burning and redness in the eyes.

Many drugs are available to treat glaucoma. If you have problems with one medicine tell your eye care professional. Treatment with a different dose or a new drug may be possible.

Because glaucoma often has no symptoms people may be tempted to stop taking or may forget to take their medicine. You need to use the drops or pills as long as they help control your eye pressure. Regular use is very important.

Laser trabeculoplasty

Laser trabeculoplasty helps fluid drain out of the eye. Your doctor may suggest this step at any time. In many cases you need to keep taking glaucoma drugs after this procedure.

Laser trabeculoplasty is performed in your doctor's office or eye clinic. Before the surgery numbing drops will be applied to your eye. As you sit facing the laser machine your doctor will hold a special lens to your eye. A high-intensity 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 several evenly spaced burns that stretch the drainage holes in the meshwork. This allows the fluid to drain better.

Like any surgery laser surgery can cause side effects such as inflammation. Your doctor may give you some drops to take home for any soreness or inflammation inside the eye. You need to make several follow-up visits to have your eye pressure monitored.

If you have glaucoma in both eyes only one eye will be treated at a time. Laser treatments for each eye will be scheduled several days to several weeks apart.

Studies show that laser surgery is very good at reducing the pressure in some patients. However its effects can wear off over time. Your doctor may suggest further treatment.

Conventional surgery

Conventional surgery makes a new opening for the fluid to leave the eye. Your doctor may suggest this treatment at any time. Conventional surgery often is done after medicines and laser surgery have failed to control pressure.

Conventional surgery is performed in an eye clinic or hospital. Before the surgery you will be given medicine to help you relax. Your doctor will make small injections around the eye to numb it. A small piece of tissue is removed to create a new channel for the fluid to drain from the eye.

For several weeks after the surgery you must put drops in the eye to fight infection and inflammation. These drops will be different from those you may have been using before surgery.

As with laser surgery conventional surgery is performed on one eye at a time. Usually the operations are four to six weeks apart.

Conventional surgery is about 60 to 80 percent effective at lowering eye pressure. If the new drainage opening narrows a second operation may be needed. Conventional surgery works best if you have not had previous eye surgery such as a cataract operation.

In some instances your vision may not be as good as it was before conventional surgery. Conventional surgery can cause side effects including cataract problems with the cornea and inflammation or infection inside the eye. The buildup of fluid in the back of the eye may cause some patients to see shadows in their vision. If you have any of these problems tell your doctor so a treatment plan can be developed.