Patient Education

Amblyopia is the lack of development of vision in one eye that is not directly caused by any eye health problem. It is not correctable with lenses alone. It is the result of poor early development, and as such, occurs before the age of six. It is estimated that 2-4% of children under the age of six have amblyopia. Amblyopia results from a large difference in the prescription between the two eyes or it can occur when strabismus (crossed eyes) is present. It can also occur when something is interfering with the clarity of the various components of the eye. This causes blurred vision in the affected eye. Because the image that is sent to the brain from the affected eye is poor, the brain will ignore this eye. As the brain ignores the eye over time, very few connections are made between the brain and the eye. It is this lack of connections between the brain and the eye that causes the eye to become amblyopic. Most of the time, there are no symptoms of amblyopia. Since only one eye is affected, the other eye usually has reasonably good vision and tends to take over all visual tasks. Unless the good eye is covered, the person will rarely notice the poor vision in the amblyopic eye. Sometimes amblyopia is associated with strabismus (crossed eyes), which may be noted as a sign/symptom.

A comprehensive optometric examination can determine the presence of amblyopia. The earlier it is diagnosed, the greater the chance for a complete recovery. That is why it is important to have your child’s vision examined at six months of age, again at age 3 and then regularly thereafter.

If caught at a young age, amblyopia is treatable. If amblyopia is the result of a difference in prescriptions between the two eyes corrective lenses are required. Therapy also involves covering the good eye so that the brain is forced to recognize the amblyopic eye. This will lead to the development of more connections between the brain and the amblyopic eye and improve vision. This is most commonly done by placing a patch in front of the good eye.

Astigmatism is not a disease, but actually a very common vision condition. It refers to a condition in which light is not focused properly on the back of the eye (retina) because the front surface of your eye (cornea) or the lens inside the eye is more oval than round. Astigmatism results in vision being blurred at all distances. Most people have some degree of astigmatism. However, only moderate to highly astigmatic eyes may need corrective lenses. Almost all levels of astigmatism can be optically corrected with properly prescribed and fitted eyeglasses or contact lenses. Laser surgery may be an option for appropriate cases.

Hyperopia, also known as farsightedness, is a vision condition in which distant objects are usually seen clearly, but close ones are not brought into proper focus. If the length of your eyeball is too short or the cornea has too little curvature, near objects cannot be brought into a sharp and clearly focused image.

If you are farsighted, you involuntarily exert extra effort to maintain clear distance vision and even greater effort to see clearly at close range. This extra effort can cause fatigue, tension and discomfort. If the crystalline lens of the eye cannot bring the object into focus, blurred vision occurs.

Common signs / symptoms of farsightedness include difficulty in concentrating and maintaining a clear focus on near objects, blurred vision, eye strain, fatigue and / or headaches after close work, aching or burning eyes, poor reading ability and general tension.

In mild cases, your eyes may be able to compensate adequately without the need for corrective lenses. In more severe cases, your optometrist may recommend glasses or contact lenses. For appropriate candidates, laser surgery can be considered.

When the normally clear lens within your eye becomes cloudy and opaque, it is called a cataract. Cataracts vary from small areas of cloudiness to large opaque areas that cause a noticeable loss of vision. Cataracts are most often found in persons over the age of 60, but they are also occasionally found in younger people, including newborns.

No one knows exactly what causes cataracts. It is known that a chemical change occurs within your eye that causes the lens to become cloudy. This may be due to advancing age or it may be the result of heredity, an injury or a disease. Excessive exposures to ultraviolet radiation, cigarette smoking or the use of certain medications are also risk factors for the development of cataracts. Cataracts usually develop in both eyes, but often at different rates.

Currently, there is no proven method to prevent cataracts from forming. Wearing sunglasses can protect your lens from harmful UV rays. A diet rich in antioxidants (such as Vitamins A, C, E, Zinc Selenium & Magnesium) is seemingly also beneficial.

Cataracts develop without pain or redness, some indications that a cataract may be forming include blurred or hazy vision, the appearance of spots in front of the eyes, or the feeling of having a film over the eyes. Increased sensitivity to glare, especially at night may be experienced.

In the early stages of a cataract, where vision is only minimally affected, your optometrist can prescribe new lenses for your glasses to give you the sharpest vision possible. When the cataracts start to interfere with your daily activities and glasses cannot improve this vision, your optometrist will refer you to an eye surgeon who may recommend the surgical removal of the cataracts.

Glaucoma is an eye disease in which it is thought the internal pressure of your eye rises to a point that the optic nerve is damaged. The exact cause of glaucoma is not known. The pressure can build either due to a problem in the production, flow or drainage of fluid normally produced in your eye. When the pressure rises, the fibers and blood vessels in the optic nerve can easily be damaged. The optic nerve carries visual information to the brain. As these fibers are damaged, the amount and quality of information sent to the brain decreases and a loss of vision occurs.

Glaucoma most frequently occurs in individuals over the age of 40 and there is a hereditary tendency for the development of the disease in some families. Primary open-angle glaucoma causes damage at an earlier age and leads to blindness at a much greater rate. There is also a greater risk of developing glaucoma when you have diabetes, high blood pressure and eye injuries. Regular optometric examinations are important for all ages to assess your risk for glaucoma.

Because most types of glaucoma open-angle glaucoma often develops painlessly and gradually, there are no early warning signs. It can gradually destroy your vision without you knowing it. A comprehensive ocular health examination is often the only way to detect glaucoma. During an eye examination the pressure in the eye is measured. Your optometrist will also look at the health of the optic nerve and measure your field of vision.

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 almost complete blindness may occur. Glaucoma is one of the leading causes of blindness in Canada.

Treatment via eye drops and surgery is usually effective in maintaining your remaining vision. Once vision is lost due to glaucoma, it cannot be restored. This is why regular preventive eye exams are so important.

The macula is the central most part of the retina that is responsible for detailed sharp vision. It is used for reading, driving, recognizing people’s faces and fine work. Macular Degeneration is a condition that causes the centre of your vision to blur while the side or peripheral vision is unaffected. It is generally related to the aging process, and is also commonly referred to as Age-related Macular Degeneration (AMD). It is the leading cause of blindness in North America in adults over the age of 55.

There are two types of AMD: dry and wet. The most common is the dry form. This is the milder form where there is a gradual degeneration of the tissue cells that make up the macula and symptoms generally develop slowly over time. The wet form is a severe leakage, or even bleeding, from weak blood vessels under the macula and symptoms progress rapidly. Wet AMD accounts for approximately 10 percent of all cases, but the dry form can develop into the wet form over time.

Initially, the most common symptom is slightly blurred vision when performing tasks that require seeing detail. A blurred spot or sense that there is dirt in the way of clear vision may develop. Over time, the blurred spot may increase in size and interfere with reading and recognizing faces. Wet AMD causes a straight line to look wavy or distorted, and dark spots may blank out portions of the central vision. There is no pain with AMD.

The risk of developing AMD increases with age. High risk groups include smokers and people who have had extensive UV exposure. AMD is also associated with conditions such as high blood-pressure, arteriosclerosis, and those with a family history of AMD.

Lifelong UV protection and general nutrition are believed to play a key role in preventing AMD. Living a healthy lifestyle by keeping your blood pressure down, reducing your intake of fatty foods and not smoking are all recommended. A diet high in antioxidants such as beta-carotene (a form of vitamin A), vitamins C and E, zinc, lutein, zeaxanthin and selenium can also help prevent AMD. Most of these antioxidants are found in fruits and leafy green vegetables. Regular eye examinations are also important in the early detection of AMD. Early stages of AMD may be found during an eye examination even if no symptoms are noticed. Your optometrist can discuss ways to minimize the possibility of vision loss due to AMD.

Currently, dry AMD has no treatment. There are older types of treatment for wet AMD that involve using lasers. One such treatment is known as Photodynamic Therapy (PDT). Recently, a new treatment for wet AMD has been used which involves injecting a drug into the eye which stops the growth of new, leaky blood vessels. Early detection and prompt intervention are crucial to the success of treatment for wet AMD. Certain vitamins can assist in slowing down the progression of AMD. It is important to realize that the use of vitamins will not reverse any vision loss that has already occurred, nor will it stop the progression of AMD completely.

Nearsightedness, or myopia, is a vision condition in which the eye ball is too long or the cornea has too much curvature and light entering the eye is not focused properly. With myopia near objects are seen clearly, but distant objects do not come into proper focus.
If your condition warrants, your Doctor of Optometry will prescribe corrective lenses for you. Glasses or contact lenses optically correct the problem by altering the way the light images enter your eyes, but they do not cure nearsightedness. Surgical procedures such as LASIK may eliminate your need for glasses.

Diabetes and its complications can affect many parts of the eye. Diabetes can cause changes in nearsightedness, farsightedness and premature presbyopia (the inability to focus on close objects). It can result in cataracts, glaucoma, paralysis of the nerves that control the eye muscles or pupil, and in decreased corneal sensitivity. Visual symptoms of diabetes include fluctuating or blurring of vision, occasional double vision, loss of visual field, and flashes and floaters within the eyes. Sometimes these early signs of diabetes are detected in a thorough optometric examination. The most serious eye problem associated with diabetes is diabetic 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. If diabetic retinopathy is left untreated, blindness can result.

With routine eye examination, your optometrist can diagnose potential vision threatening changes in your eye 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 your risk of developing retinopathy. Other factors that increase the risk of developing retinopathy include smoking, high blood pressure, drinking alcohol and pregnancy.

In the early stages, diabetic retinopathy is monitored through eye health examinations.
If necessary, it may be treated with laser therapy. A bright beam of light is focused on the retina, causing a burn which seals off leaking blood vessels. In other cases, surgery inside the eye may be necessary. Early detection of diabetic retinopathy is crucial, as treatment is much more likely to be successful at an early stage. See your optometrist, for a thorough eye examination when you are first diagnosed as a diabetic, at least annually thereafter and more frequently if recommended.

Presbyopia is a natural part of the aging process in which the crystalline lens of your eye loses its flexibility. This results in difficulty in focusing on close objects. The lens in your eye continues to grow and produces more and more cells. Eventually the lens loses most of its elasticity and therefore, loses most of its focusing ability. The decline in focusing ability takes place over the course of many years, but the effects usually become apparent in the early to mid-forties. Initial signs/symptoms of presbyopia include the tendency to hold reading materials at arms length, blurred vision at normal reading distance and eye fatigue along with headaches when attempting to do close work. The effects of presbyopia constantly change the ability of the crystalline lens to focus properly. As a result, approximately every 2-3 years, changes in your eyewear are necessary to maintain correct vision between ages 40-60. Depending on other vision conditions, presbyopia is managed with the use of reading glasses, bifocals, trifocals, progressives, or in some cases, contact lenses.

Strabismus, also known as crossed-eyes, is a vision condition in which your eyes are not properly aligned with each other. For a variety of reasons, one or both of your eyes turn in, out, up or down. Coordination of your eyes muscles develops in your first six years. Failure of your eye muscles to adjust properly can lead to crossed-eyes. Children under 6 are the ones most affected by crossed-eyes, but this often first appears between birth and age 21 months. It is estimated that five percent of all children have some type or degree of strabismus. Although rare, strabismus sometimes begins in adulthood, but this is usually the result of a stroke, tumor or other vascular disease.

Children with strabismus may initially have double vision. This occurs because both eyes are not focusing on the same object. In an attempt to avoid double vision, the brain will eventually disregard the image from one eye. In time, the ignored eye will become unable to function normally and will become largely unused. This may result in the development of lazy eye (amblyopia).

Treatment for strabismus can include eyeglasses (regular or bifocal), prisms, vision therapy, and in some cases, surgery. Strabismus can be corrected with excellent results if detected and treated early.