Read below to learn about common eye conditions and eye diseases.
Farsightedness, or hyperopia, as it is medically termed, 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.
Farsightedness can be effectively diagnosed during a comprehensive optometric examination. 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. If glasses or contact lenses are prescribed, it may take a few days to adjust to them. After that, farsightedness will probably not significantly affect your lifestyle.
Nearsightedness, or myopia, as it is medically termed, is a vision condition in which near objects are seen clearly, but distant objects do not come into proper focus. When your eyeball is too long or the cornea has too much curvature, light entering the eye is not focused properly. Nearsightedness is a very common vision condition that affects nearly 30 percent of the Canadian population. It normally occurs in school age children. Since the eyes continue to grow during childhood, nearsightedness usually occurs before the individual reaches the age of 20.
Eyeglasses or contact lenses optically correct the problem by altering the way the light images enter your eyes, but they do not cure nearsightedness. If glasses or contact lenses are prescribed, it may take up to 2 weeks to adjust to seeing clearly with them.
Presbyopia is a vision condition 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. It varies from person to person. Although presbyopia may seem to develop suddenly, the actual decline takes place over the course of many years. Presbyopia usually becomes apparent to people in their early to mid-forties.
Some signs/symptoms of presbyopia include the tendency to hold reading materials at arm’s length, blurred vision at normal reading distance and eye fatigue along with headaches when attempting to do close work. A comprehensive eye examination by a Doctor of Optometry will include testing the quality of your near vision. This will determine the extent, if any, of presbyopia. 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.
Astigmatism occurs when the front surface of your eye (cornea) or the lens inside the eye is slightly irregular in shape, resulting in vision being blurred at all distances. Astigmatism is not a disease, but is actually a vision condition that is quite common. When the front of your eye or the lens inside the eye is more oval than round, light does not focus properly on the back of your eye (retina). Astigmatism is caused by small differences in the growth and alignment of the components of the eye. In some cases, it may be hereditary or it may result from such factors as pressure of the eyelids on the cornea.
People with severe astigmatism will usually have blurred or distorted vision. Those with mild astigmatism may experience headaches, eyestrain, fatigue or blurred vision at certain distances.
A comprehensive eye examination by your Doctor of Optometry will include tests for astigmatism. 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.
Strabismus (Crossed Eyes)
Strabismus, more commonly 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 and their ability to work together as a team develops in your first six years. Failure of your eyes (or more precisely, your eye muscles) to adjust properly can lead to crossed-eyes. Strabismus may also have a tendency to be hereditary.
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, tumour or other vascular disease.
A child will not outgrow crossed-eyes. In fact, the condition may get worse without treatment. 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). Parents may be the first to notice a slight wandering of one or both of a child’s eyes. A comprehensive vision examination by a Doctor of Optometry is recommended by the age of three, as parents often will not notice it. The examination can determine if strabismus is present. 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.
Amblyopia (Lazy Eye)
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. Amblyopia 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. This is why lenses alone cannot correct the problem.
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.
Poor vision that cannot be corrected fully with glasses may indicate a condition known as conical cornea or keratoconus. A rare condition, keratoconus primarily affects people in their early 20′s.
With keratoconus, the cornea, the “clear window” at the front of the eye, may become thin and bow outwards. It is this irregular distortion of the cornea that makes vision correction with glasses less than optimal. For this reason other means of correcting vision are often necessary.
Mild to moderate keratoconus is best corrected with rigid gas permeable contact lenses, which provide a smooth surface in front of the cornea, making clear vision possible. Because the lens is rigid, the tears between the lens and the cornea form a ‘liquid lens,’ which smoothens the irregularities of the cornea and makes clear vision possible again. Soft lenses, which ‘wrap’ onto the cornea and take up its shape much more closely than rigid lenses, are less successful at correcting keratoconus.
As keratoconus progresses, some scarring of the cornea can occur. Eventually, contact lenses may no longer be a successful treatment. Instead, the cornea may need to be replaced surgically with a cornea of more regular shape. The prognosis for corneal replacement surgery is generally very good.
Floaters and Spots
Floaters (often called spots) are small, semi-transparent specks or particles within the eye that become noticeable when they fall within the line of sight. They may also appear with flashes of light.
Almost everyone sees a few floaters at one time or another. They can occur more frequently and become more noticeable as you grow older. If you notice a sudden change in the number or size of floaters, you should contact your Doctor of Optometry right away, so you can be sure they are not the result of a more serious problem.
The inner part of your eye is made up of a clear, jelly-like fluid known as the vitreous. Occasionally, small flecks of protein and other matter become trapped in the vitreous during the formation of the eye before birth and remain in the vitreous body. Floaters and spots may also be caused by the deterioration of the eye fluid or its surrounding parts, or by certain injuries or eye diseases.
Floaters are generally translucent specks of various shapes and sizes. They may also appear as bugs, threadlike strands or cobwebs within the eye. Since they are within the eye, they move as the eye moves and seem to dart away when you try to look at them directly.
Most floaters are normal and rarely cause blindness. But, floaters can be indications of more serious problems, such as a retinal hole, tear or detachment, and if you see them you should have a comprehensive optometric examination to determine the cause.
As part of a comprehensive eye examination, your Doctor of Optometry will thoroughly evaluate the vitreous and retina of your eyes. Your optometrist uses these instruments to examine the health of the inside of your eyes and may also observe the floaters within your eye. This is often done after the doctor puts special drops in your eyes to make the pupils larger (called dilation) to allow a fuller view of the inside of your eyes.
Colour deficiency occurs when your ability to distinguish colours and shades is less than normal. The term “colour blind” is often used, but usually incorrectly. Only a very small number of people are completely unable to identify any colours. Colour deficiency is more common in males than females.
Colour deficiency is usually inherited, but can also result from certain diseases, trauma or as a side effect of certain medications. It happens when an individual partially or completely lacks one or more types of the three kinds of cones.
People who are colour deficient are generally unaware of their condition. They assume that everyone sees things the way they do. As a result, a complete optometric examination, including a test for colour vision, is recommended. The test for colour deficiency is a relatively simple one, typically involving the viewing of a series of coloured designs. The designs have been created in such a way that a person with normal colour vision can see certain figures in the designs. A colour deficient person will not be able to distinguish the figures.
Every child should be checked for colour deficiency by at least age five. It is important to detect colour deficiency early because colour coded learning materials are used extensively in the primary grades. In addition, colour deficiency may affect the career path of an individual, since the ability to distinguish colours is an important aspect of some jobs, such as pilots, electricians, some military personnel, police officers and others.
Unfortunately a cure for colour deficiency has not yet been discovered. A person with colour deficiency can, however, be taught to adapt to the inability to distinguish colours. For example, you can be taught to recognize the brightness and location of a traffic light rather than the colour itself. It is sometimes possible to increase the ability to distinguish colours with the use of special filters. A special red tinted contact lens, used in one eye, and other devices are used, in some cases, to aid persons with certain colour deficiencies.
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.
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.
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.
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.
Many patients with sight loss due to AMD can benefit from low vision aids. Your optometrist can prescribe magnifying devices to enhance both distance and reading vision. These aids will not restore sight to normal levels but they allow people to maximize their remaining vision. Your optometrist may also train you to use the Amsler grid, which is a tool that can assist in testing the progression of AMD.
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 pressure that builds up is due to a problem in the production, flow or drainage of fluid normally produced in your eye. Glaucoma is one of the leading causes of blindness in Canada.
The exact cause of glaucoma is not known. For some reason, there is an overproduction of fluid and / or the passages that normally allow fluid within your eye to drain out become clogged or blocked. This results in fluid building up within your eye and increasing pressure on the optic nerve. The nerve fibres and blood vessels in the optic nerve can easily be damaged by this pressure. An injury, infection or tumour in or around the eye can also cause the pressure to rise.
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.
The optic nerve, at the back of the eye, carries visual information to the brain. As the fibres that make up the optic nerve are damaged, the amount and quality of information sent to the brain decreases and a loss of vision occurs.
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.
Primary open-angle glaucoma often develops painlessly and gradually. There are no early warning signs. It can gradually destroy your vision without you knowing it. Acute angle-closure glaucoma may have symptoms such as nausea, eye pain, red eyes, blurred vision and haloes around lights.
A comprehensive ocular health examination is often the only way to detect glaucoma. Your optometrist can include in your examination a simple and painless procedure called tonometry, which measures the internal pressure of your eye. Your optometrist will also look into your eye to observe the health of the optic nerve and measure your field of vision.
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.
When the normally clear lens within your eye becomes cloudy and opaque, it is called a cataract. Cataracts vary from extremely 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 exposure to ultraviolet radiation present in sunlight, 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 is a tremendous benefit as they protect your lens from harmful UV rays, which can speed up cataract formation. 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. A temporary improvement in near vision may also occur and increased sensitivity to glare, especially at night may be experienced.
A comprehensive eye examination by a Doctor of Optometry can determine if you have a cataract forming. How are cataracts treated?
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. The surgery is relatively uncomplicated and has a success rate of at least 95 percent.
Cataracts may develop slowly over many years or they may form rapidly in a matter of months. Some cataracts never progress to the point that they need to be removed. When a change in glasses can no longer provide functional vision, your optometrist will arrange a consultation with a cataract surgeon.
Intraocular lens implants, inserted in your eye at the time of surgery, serve as a “new lens” and sometimes give you good distance vision without glasses. Your near vision will still be blurred. Your Doctor of Optometry will prescribe new lenses for your glasses about 4 weeks after surgery to maximize your distance and near vision.
Diabetes, simply stated, is a disease that prevents your body from making or using insulin which in turn leads to increased sugar levels in your bloodstream.
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.
Yes, in a 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.
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.
Anterior uveitis is an inflammation of the middle layer of the eye, which includes the iris and adjacent tissue, known as the ciliary body.
If untreated, anterior uveitis can lead to other eye problems and cause permanent damage. It usually responds well to treatment, however, there may be a tendency for the condition to recur.
Anterior uveitis can occur as a result of trauma to the eye, such as a blow or foreign object penetrating the eye. It can also be a complication of other eye disease, or it may be caused by general health problems such as rheumatoid arthritis, rubella and mumps. In most cases, there is no obvious underlying cause.
Signs/symptoms may include a red, sore and inflamed eye, blurring of vision, sensitivity to light and an irregular pupil.
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: Is 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.
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.
Conjunctivitis (Pink Eye)
Conjunctivitis is an inflammation of the conjunctiva, a thin, transparent layer covering the surface of the inner eyelid and a portion of the front of the eye. This condition appears in many forms and affects people of all ages.
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.
Common signs/symptoms of conjunctivitis are red eyes, inflamed inner lids, watery eyes, blurred vision and sandy or scratchy feeling in the eyes. With the infectious form, there may be a pus-like or watery discharge around the eyelids.
To avoid giving infectious conjunctivitis to others, keep your hands away from your eyes; thoroughly wash your hands before and after applying eye medication; do not share towels, washcloths, cosmetics or eye drops with others and 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’s important to have your condition diagnosed and properly treated quickly.
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. They are fought off by your body’s immune system. But, some antibiotics may be prescribed to prevent secondary bacterial infections from developing.
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.
The tears your eyes normally produce are necessary for overall eye health and clear vision. Dry eye occurs when your eyes do not produce enough tears or produce tears which do not have the proper chemical composition.
Dry eye symptoms can result from the normal aging process, hormonal changes, exposure to environmental conditions, problems with normal blinking or from medications such as antihistamines, oral contraceptives or antidepressants. Dry eye can also be symptomatic of general health problems or other diseases or can result from chemical or thermal burns to the eye.
The common sign/symptoms include stinging, itchy, scratchy and uncomfortable eyes; and sometimes having a burning feeling or a feeling of something foreign within the eye. You may experience increased dry eye symptoms on awakening. Some people experience an overly wet eye. This is a natural reflex to comfort a dry eye.
During the examination, your Doctor of Optometry will ask you questions about your general health, your use of medications and your home and work environments to determine any factors which may be causing dry eye symptoms. This information will help your doctor decide whether to perform dry eye tests. These tests use diagnostic instruments, which allow a highly magnified view of your eyes and sometimes use special dyes. Your doctor will evaluate the quality, the amount and the distribution of tears to detect signs of dry eyes.
Dry eye usually cannot be cured, but your eyes’ comfort can be improved and eye health maintained through use of artificial tears. For more severe dry eye, gels and ointments 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. Treating any underlying systemic disease or a change of diet can also be helpful at times.
If dry eye is untreated, it can harm your eyes. Excessive dry eye can damage tissue and possibly scar the cornea of your eye, impairing vision. Dry eye can make contact lens wear more difficult due to increased irritation and greater chance of eye infection. To keep dry eye symptoms in check, you and your Doctor of Optometry need to work together. Follow your doctor’s instructions carefully. If you have increased dryness or redness that is not relieved by the prescribed treatment, let your optometrist know as soon as possible.
Retinoblastoma is a rare cancer of the eye that typically affects children between birth and five years of age. The incidence of RB is 1 in 15,000 live births, with about 23 children being affected in Canada each year. The retinoblastoma tumour(s) originate in the retina, the light sensitive layer of the eye which enables the eye to see. When the tumours are present in one eye, it is referred to as unilateral retinoblastoma, and when it occurs in both eyes it is referred to as bilateral retinoblastoma.
Parents are often the first to notice the signs and symptoms of retinoblastoma. These include:
The most common indicator of RB is whiteness reflected in the pupil, particularly noticeable when the pupil is dilated. Many parents refer to this reflection as “cat’s eye”. Medically, what is being observed is known as leukocoria.
One or both of the child’s eyes may turn inward or outward. This is often described by parents as “lazy eye,” “crossed eyes,” or a wandering eye. The medical name for this is strabismus.
More rarely, a child’s retinoblastoma may be indicated by redness and/or swelling of the eye(s).
None of these indicators is conclusive of retinoblastoma, but if a parent notices these symptoms in their child, a visit to an optometrist or a referral to an ophthalmologist should be sought immediately.
In our eye health library, you’ll find articles elucidating different eye conditions and other common terms used during and eye examination.