More about your vision and eye health
This information is for general education only and may not be suitable for everyone. It is not intended to be optometric advice and if any of the issues raised affect you, we recommend you seek advice from your OPSM or Budget Eyewear optometrist. Myopia, or short-sightedness, is a form of refractive error. It occurs when the power of the eye is too strong or the eyeball grows too long. In short-sightedness, distance vision is blurred and near vision is usually clear (although may be blurred if the myopia is very high or astigmatism or presbyopia is also present).
Often myopia begins in childhood or the teenage years and usually increases up until the early 20s, although it may stop earlier or later. People with high myopia are more prone to retinal problems such as retinal tears and retinal detachments, so they should have more frequent eye examinations than the average person. The blurred vision caused by myopia can be corrected using glasses, contact lenses and sometimes refractive surgery.
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What is hyperopia?
Hyperopia is a condition of the eye where the eye needs to focus harder for all distances than a perfect eye. A little hyperopia is not a problem because the eye can compensate easily. However, if there is a significant amount of hyperopia the effort of focusing (called accommodation) can lead to symptoms.
A hyperopic person can have normal vision, but the greater the hyperopia the harder it is to focus. Vision may become blurry, especially for close objects, because the closer the object the more focusing is required. Hyperopic people may get tired eyes or headaches after a lot of visual work, even if their vision is clear. Reading is more difficult and school work can be affected.
Hyperopia tends to increase with age. We all find it harder to focus on close objects as we get older (due to presbyopia). Hyperopes have trouble sooner and may need reading glasses earlier because they have to focus more to start with. Because a hyperopic person often can see well in the distance, a letter chart test alone may miss hyperopia. Special tests have to be used, including retinoscopy and refraction.
In treating hyperopia, your OPSM optometrist has many things to consider when making a decision and symptoms are very important. In general, young people who are slightly hyperopic do not have problems. If they do, they may need glasses, mainly for close work such as reading and using computers. Older people, or young people with significant hyperopia, often have problems because focusing requires much effort. Their vision is more likely to be blurred, especially for close objects. They usually need glasses for reading and sometimes for distance vision as well. Hyperopia is often thought to be hereditary or due to developmental problems.
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What is presbyopia?
Presbyopia is a condition of the eyes whereby the eyes lose their ability to focus on close objects. It is a normal change in function, not a disease. Everybody gets it, whether they are myopic, hyperopic, astigmatic or perfectly sighted for distance vision.
To understand presbyopia, it is important to understand how your eyes change their focus for viewing close objects. Normally they are focused for distance vision. Inside the eye there is a lens about the size of a pea. To focus on close objects, a special muscle in the eye changes the shape of the lens. This process is called accommodation. With age the lens loses its flexibility and is less able to change its shape. This is a completely normal ageing change, just like stiffening joints or greying hair. The loss in lens flexibility is the reason that close focusing becomes more difficult. The muscle responsible for the process does not weaken significantly. This is important to know as it means that eye exercises will not significantly help or cure the problem.
The effects of presbyopia usually occur from about the ages of 40 - 45. However, the process starts from a very young age - it is a slow downhill slide from about the age of 10. A ten-year-old can focus as close as 6 centimetres from the eye. A twenty year old can only focus to 10 centimetres, and a 30 year old to about 15 centimetres. A fifty year old has to put the newspaper on the ground and stand up to see it clearly without reading glasses!
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What is astigmatism?
Astigmatism is a form of refractive error (others include short sightedness or long sightedness). In astigmatism the front of the eye (the cornea) or the crystalline lens inside the eye does not have spherical surfaces, instead being a different curvature in one direction to another. To help visualise this, an astigmatic eye has curves like a rugby ball, and a normal eye has curves more like a soccer ball. As a result the eye is more shortsighted (or less longsighted) in one direction than another, and lines in some directions may be clear, but other directions blurry.
Astigmatism blurs things at all distances, and makes it harder for the eyes to focus accurately. Sometimes even small amounts of uncorrected astigmatism are associated with headaches or sore eyes during concentrated visual activity.
Astigmatism can be corrected by glasses or contact lenses. Irregular astigmatism sometimes occurs in conditions where the cornea (most commonly) or crystalline lens is warped or distorted. This may happen in conditions such as keratoconus or as a result of injury. Usually rigid contact lenses give better vision than glasses in cases of irregular astigmatism of the cornea.
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What is a pterygium?
A pterygium is a growth of tissue that occurs on the surface of the eye. It originates from the clear conjunctival tissue that covers the white part of the eye and is most commonly located on the exposed surface of the eye closest to the nose. The eye may appear more red in the area where the ptyergium is located, or feel slightly irritated or dry.
Sometimes pterygia can grow over the cornea (clear front surface of the eye) causing vision to be obstructed or astigmatism to be produced. If this occurs the pterygium can be removed surgically by an eye specialist (ophthalmologist).
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What is glaucoma and how do I know if I have it?
Glaucoma is an eye disease in which the nerve fibres at the back of the eye slowly die, leading to vision loss and blindness. It has been linked to a build-up of pressure inside the eye. The pressure in the eye can increase if the fluid flowing out of the eye is not balanced with that flowing in, for instance, if too much fluid is produced or the outflow of fluid becomes obstructed. Symptoms are minimal in most cases, side vision is slowly lost and may not become noticeable until the disease is quite advanced.
In assessing the eye for glaucoma, your OPSM optometrist tests the pressure of the eyes. They also assess the health of the optic disc (the point of entry of retinal nerves into the brain) to check for nerve fibre loss. If either of these tests suggest glaucoma is present, a computerised visual field test may be carried out. This tests for early losses in peripheral (side) vision. If glaucoma is present your OPSM optometrist can refer you to an eye specialist for treatment.
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What is age-related macular degeneration (ARMD or ARM)?
Age-related macular degeneration (ARMD or ARM) consists of two types: dry macular degeneration and wet macular degeneration. Most people with ARMD have dry ARMD. In dry ARMD, waste products build up at the back of the eye. It can affect one or both eyes. Central vision may gradually decrease in dry ARMD. Wet ARMD is the more severe form of the condition in which new blood vessels grow at the back of the eye.
ARMD is the result of ageing processes in the eye. Some of the layers of the retina thicken and waste material which is usually removed from the retina forms deposits, distorting the retina. This distortion can cause damage to the other layers of the retina. In about 10% of cases, new blood vessels grow into the macula from beneath. These newly-formed vessels are fragile and often leak blood into the retina where the blood causes scar tissue to form. The scarring can block out central vision.
There are also some other forms of macular degeneration which are inherited and not associated with ageing. When most body tissues such a muscle, skin or bone are damaged, the tissues' cells have the capacity to regrow and repair the damage. Because nerve cells cannot regenerate, damage to nerve tissue, such as the retina, is usually permanent and irreversible. This is why the vision loss in ARM is so difficult to treat.
Where new blood vessels have appeared in the macula area, laser surgery may be used. In this treatment a focused, intense beam of laser light is used to seal off leaking blood vessels and to prevent new vessels growing. This treatment is most effective when it is applied in the very early stages of the disease, before extensive damage has been done. There are also some emerging drug treatments for wet ARM. While there is little which can be done to prevent or cure ARM, people with the disease can be helped to continue functioning normally.
Many patients with ARM will eventually come under the classification of being a low vision patient. Special help in the form of low vision devices is available from OPSM optometrists and specialist low vision clinics. Low vision devices enable patients to make the most of their vision and include items such as miniature telescopes, high-powered reading glasses, hand-held and stand magnifiers, closed circuit televisions and other simpler aids such as large-print books.
For treatment of ARM to be effective, it must be diagnosed as early as possible. Regular eye tests are the key to early detection of retinal changes and other signs of disease. If you notice any change in the quality of your vision, have your eyes examined immediately. Regular eye tests are particularly important for people over the age of 50 and people whose families have a history of eye problems.
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What are the risk factors associated with age-related macular degeneration and how can it be treated?
Age-related macular degeneration (ARMD) is the leading cause of blindness in Australia. It is more common with age, in people with European backgrounds or fair skin, smokers, and those who have had a lot of exposure to sunlight. Wearing a hat and sunglasses when in sunlight, and consuming plenty of antioxidant containing foods such as green leafy vegetables and oily fish may help to prevent the condition.
The progression of the disorder can sometimes be minimised through the use of drug or laser treatment, however once vision is lost it cannot often be restored. Those with reduced vision due to ARMD can benefit from the use of magnifiers and other low vision aids. Your OPSM optometrist can assist in determining which of these visual aids are most suitable for you.
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What is a cataract?
A cataract is an opacification or clouding of the lens inside the eye. It is not a growth over the surface of the eye. Clouding of the lens occurs slowly throughout life but usually does not interfere with vision until old age. Poor vision results because the cloudiness interferes with light entering the eye. The opacities in the lens scatter the light, causing hazy vision, in the same way that a dirty window scatters light.
Most cataracts are a result of ageing and long-term exposure to ultraviolet light. Some are caused by injury and certain diseases and in rare cases by exposure to toxic materials and radiation. Occasionally cataracts are present at birth, due to the baby's mother having had rubella during the pregnancy, or genetic defects. Usually cataracts affect both eyes but often develop at different rates in each eye.
If untreated, cataracts can cause blindness. Blindness can be prevented by early detection of the cataracts and, if necessary, by having them removed surgically. Your OPSM optometrist will refer you to an eye specialist if they consider that you need medical treatment for your cataracts.
There is no proven method of preventing cataracts. Long-term exposure to ultraviolet light is thought to induce cataracts, so a brimmed hat and approved sunglasses should be worn in sunlight. Cataract surgery is now a relatively minor procedure. Often it is performed under a local anaesthetic. Depending on the patient, the surgery may be performed on an out-patient basis. This means that the patient attends a hospital or clinic for the surgery and is able to go home the same day. The surgery is performed by an ophthalmologist, a medical doctor who specialises in eye surgery. Your optometrist will refer you to an ophthalmologist if necessary.
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What causes cataracts?
Everyone gets cataracts if they live long enough! Most cataracts occur as a normal aging change in the eye, and typically appear between the ages of 65 and 80, although they may appear earlier. Vision is not generally affected straight away, it might take years or decades to become a problem. The normal lens is clear at birth and becomes more opaque or cloudy with age. This process can be accelerated by excess exposure to sunlight.
Cataracts can also form in response to severe injury to the eye, radiation, or as a side effect to some eye diseases or medications. Some cataracts are inherited, and some occur as a result of illness, such as diabetes or intrauterine rubella.
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How can cataracts be treated?
If we live long enough, we all get cataracts. They are a normal part of life. In the early stages of a cataract no treatment is necessary. When the cataract begins to interfere significantly with vision, cataract surgery can be carried out.
When required, your OPSM optometrist can refer you to an ophthalmologist (eye doctor or eye surgeon) who will perform the procedure. It involves removal of the cloudy lens and replacement with an artificial lens. This procedure is the most common operation performed of all types, and has one of the highest success rates. It is commonly done under local anaesthetic, and is often day surgery, with vision back to normal the very next day!
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What is a retinal detachment?
A retinal detachment is a separation of the layer at the back of the eye containing the 'seeing' cells (the retina) from the back of the eye. A retinal detachment sometimes occurs when a tear or hole develops in the retina and the fluid of the eye fills into the hole, pulling the retina away. Retinal tears or holes can occur following an injury to the eye and are more common in short-sighted (myopic) eyes. If the detachment becomes large and is not treated blindness can result.
Symptoms of a retinal detachment include flashes of light, showers of spots or the sensation of a curtain or shadow coming over the vision. Retinal detachments must be treated urgently to prevent vision being lost. Common forms of treatment involve laser or freezing therapy (cryotherapy). Retinal tears may also be treated by these methods in order to prevent a retinal detachment occurring.
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How does diabetes affect the eyes?
Diabetes is a disease that affects the small blood vessel systems throughout the body. Diabetes can cause bleeding and accumulation of fluid in the retina of the eyes. This condition is known as diabetic retinopathy. In advanced cases new blood vessels form inside the eyes, which leak fluid and cause scar tissue to form, which can lead to vision loss or blindness.
People with diabetes also have a greater risk of cataracts and glaucoma. The risk of ocular complications in people with diabetes increases with the amount of time they have had diabetes and if sugar levels are poorly controlled. It is important that all diabetics have regular yearly eye tests.
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I see floating spots in my vision, what are they caused by?
Inside the eye is a jelly like substance called the vitreous humour. This keeps the eyeball inflated. Sometimes when we look at an object with a bright background, such as the sky on a sunny day, we see little floating spots in our vision. These are particles inside the vitreous of the eye casting shadows on the retina.
With age, the vitreous can contract and pull away from the back of the eye. Sometimes this can cause a large spot or floater to appear in the vision. When the floating spot first occurs, a flash of light may also be noticed as the movement of the vitreous pulls on the retina. Sometimes this can also cause bleeding at the back of the eye.
If a sudden increase in floaters occurs, or flashes of light are experienced, an urgent appointment should be made with your OPSM optometrist or ophthalmologist so that the health of the eyes can be thoroughly examined, as this may also be a sign of a retinal tear or detachment, which can cause significant vision loss.
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What causes dry eyes and what can be done about it?
Dry eye results when the eyes do not produce enough tears or when the different tear components are not produced in ideal proportions. Dry eye can be more pronounced in certain conditions such as during contact lens wear or in air-conditioned environments. Symptoms include dry scratchy eyes, the feeling that something is in the eyes or even watering of the eyes.
Dry eye can be treated with artificial tear supplements, which are applied to the eye in the form of ointments or drops. Your OPSM optometrist can advise you about which tear supplements are most suitable for you.
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What is colour blindness?
Most people with colour vision deficiencies can see colours; true 'colour blindness' is extremely rare. About 8% of males and 0.5% of females have a colour vision deficiency. Most commonly this involves confusing certain shades of reds and greens. Colour vision deficiencies are inherited genetically. Due to colour deficiencies being linked to the X chromosome, males always inherit the condition from their mother. Females only become colour deficient if both parents carry the gene. Sometimes colour vision deficiencies are associated with eye disease or occur as a side effect of medications.
Colour vision deficiencies cannot be cured. Special coloured lenses have been developed in attempt to normalise colour vision. Although these can assist in distinguishing differences between colours that may otherwise appear the same they cannot make colours look the same as someone without a colour vision deficiency would see them. Sometimes a person with a colour vision deficiency can be restricted from entering certain professions such as defence forces, commercial pilot or holding a commercial drivers licence.
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What is conjunctivitis?
Conjunctivitis is an inflammation of the clear tissue that covers the white of the eye (the sclera) on the eye's surface. It can be caused by a bacterial or viral infection, toxic response or allergy. The eye may feel itchy or irritated and appears red. A mucousy or watery discharge may be present and sometimes the eyes become stuck together on waking.
Bacterial conjuctivititis may be treated with topical antibiotics. Allergic conjunctivitis is often experienced during spring and may be treated with a topical antihistamine.
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Are my eyes causing my headaches?
Headaches are very frustrating things. There are so many potential causes of headaches, and eyes are not commonly the reason for headaches. However, it is worth a visit to an OPSM optometrist to rule (in or out) the eyes as a cause of your headaches.
Headaches caused by eyestrain are most often located at the front of the head, around the temples or behind the eyes. Headaches associated with the eyes are usually experienced towards the end of the day or following long periods of close work such as reading or computer use. Eyestrain headaches may be due to uncorrected hyperopia (longsightedness), astigmatism or presbyopia. Myopia can also cause headaches due to the habit of squinting myopic people use to try to see better in the distance. Other causes include focussing problems or eye co-ordination problems. Sometimes more serious causes of headaches can be pinpointed during an eye test. Headaches upon waking or that vary in intensity with changes in posture are unlikely to be due to the eyes. If the eyes are not determined to be the cause of the headaches your general practitioner should be consulted.
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What should I do if my child has an eye turn (strabismus)?
If you notice that your child has an eye turn (strabismus) it is important to have the child's eyes examined by an OPSM optometrist or ophthalmologist. The earlier in life an eye turn is treated the more likely treatment will be successful.
Strabismus can be treated through glasses wear, eye exercises and eye surgery. Treatment aims to straighten the eyes, teach them to work together and maximise vision. The turned eye of a young child can quickly develop amblyopia. Amblyopia is a condition in which the vision of an eye never fully develops. If amblyopia is treated while a child is still young the sight in the eye can sometimes be improved. Amblyopia is treated through eye exercises and eye patching. Amblyopia can also result in one or both eyes in the absence of an eye turn if a very high uncorrected glasses prescription is present. Amblyopia cannot develop in adults.
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What damage does the sun or ultraviolet light do to the eyes?
Skin is not the only thing that can be damaged by sunlight; your eyes can also be affected by excessive exposure to bright light and ultraviolet (UV) rays. UV-A and UV-B rays can contribute to cataracts (a permanent clouding of the lens inside the eye that reduces vision), as well as age-related macular degeneration (the leading cause of vision loss and legal blindness among Australians over 60 years of age). UV light also causes the surface of the eye (conjunctiva and sclera) to discolour and become lumpy (pinguecula and pterygium), which can look ugly and make the eye more prone to drying and other irritation. Acute sunburn to the eyes causes 'snow blindness' or 'welder's flash', which is where the surface layers of the eye peel away and can cause from mild to extreme pain and discomfort and reduced vision until the surface layers grow back.
To avoid harmful sun damage, take measures to protect yourself: wear sunglasses that block both glare and 99 to 100 % of UV-A and UV-B rays. UV protection is also available for your clear prescription glasses, in all lens types. Select frames that shield light and rays from all angles - wrap-around sunglasses are the best choice. Also, wearing a wide-brimmed hat and avoiding prolonged sun exposure, especially during peak hours when the rays are strongest, are other ways to protect yourself. Take note, clouds aren't effective filters of the harmful rays, so be sure to wear your sunglasses on bright, cloudy days too!’
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What are multifocal/progressive lenses?
Multifocals (or graduated or progressive lenses) contain three power areas: the top portion of the lens for distance vision, the central portion for intermediate vision (such as for computer use) and the lower portion for reading. The powers gradually change down the lens, so that there are no visible markings on the lens. Multifocals correct vision at all normal distances and can provide the most convenient and natural vision of all lens types.
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What are bifocals?
Bifocals are used to correct both distance and close up vision. The lens contains a distance portion which can be used to correct short or long sightedness or astigmatism, with a smaller section visible on the lower portion of the lens which contains a stronger lens power for reading.
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How often should I have my eyes tested?
It is recommended that you see your OPSM optometrist for an eye test at least every two years. It may be necessary to have your eyes tested more frequently, eg. if you have diabetes your OPSM optometrist may recommend that you have the health of your eyes assessed each year. Some children should also have an annual review.
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What does my optometrist test for during an eye test?
During a full eye test your OPSM optometrist will check your ability to see in the distance using a letter chart (visual acuity). Your distance prescription will be checked as well as your reading prescription. The ability of the eyes to move together correctly and focus accurately can be checked. The health of the back of the eyes (the retina, macula and optic discs) should be assessed as well as the health of the front of the eyes (cornea, conjunctiva, eyelids, iris and lens), which includes checking for cataracts. Tests for glaucoma, including checking the pressure of the eyes, should also be carried out.
If indicated, your OPSM optometrist may conduct further tests such as using drops to dilate the pupil to more thoroughly check the health of the eyes, or administering a visual fields test to screen for conditions such as glaucoma. Further appointments may be made to fit contact lenses to the eyes, or provide vision training for eye movement or eye focussing disorders.
This information is for general education only and may not be suitable for everyone. It is not intended to be optometric advice and if any of the issues raised effect you, we recommend you seek specific advice from your OPSM optometrist.
