This page provides information about some of the more common eye diseases. Eye diseases are relatively rare, although they become more common as we get older. All eye diseases should be regarded as serious - even diseases that appear to be mild can have the potential to cause serious damage if they are not treated appropriately. If you suspect that you have any eye disease, you should seek immediate care from a qualified professional.
Many serious eye diseases do not have any dramatic symptoms, indeed, some people with serious eye diseases do not even realise that there is anything wrong until their eyes have suffered irreversible damage. Everyone should have a checkup from an optometrist or ophthalmologist every two years, in order to detect any eye disease before it has a chance to cause serious damage. Your optometrist may recommend more frequent checks if you are at higher risk of eye disease.
For more information on some common eye diseases, choose from the list below:
· Glaucoma
· Age-related macular degeneration
· Pterygium
Glaucoma
What is glaucoma?
Glaucoma is a condition in which the nerve cells which transmit information from the eye to the brain become damaged. This prevents visual information from getting from the retina in the eye to the brain. Glaucoma is often associated with a build-up of pressure in the eye. The eye is filled with fluid which is constantly being replaced. If excessive amounts of fluid are produced, or if it cannot drain away properly, the pressure inside the eye can increase. In some forms of glaucoma, the pressure inside the eye can become extremely high, but in other forms the pressure may remain normal.
What causes glaucoma?
The exact causes of glaucoma are not known. In some cases the drainage network of the eye may not be formed properly, or may become blocked by natural materials or due to injury; in other cases there is no clear cause.
Is the damage that occurs in glaucoma serious?
If untreated, glaucoma can cause blindness. As the nerve cells are progressively damaged, the ability to see objects in different parts of the visual field is lost. The damage to the nerve cells cannot be reversed although it is often possible to prevent further damage. This damage can progress until only central vision is left or until the person is completely blind. The longer the disease is left untreated, the greater is the likelihood of damage. Modern examination techniques and treatment have made glaucoma a rare cause of blindness in Australia.
How can I tell if I have glaucoma?
Often you will not be aware that you have glaucoma until it is too late. Usually there are no symptoms until permanent damage has occurred. In some cases the increased pressure in the eye will cause blurred vision, apparent coloured rings around lights, loss of side vision, and pain and redness of the eye.
How does an optometrist diagnose glaucoma?
To diagnose glaucoma the optometrist looks at the nerve fibres at the back of the eye, examines the eye's drainage network, measures the pressure in the eye with a special instrument called a tonometer and sometimes tests the field of vision. These tests are simple and painless.
How is glaucoma treated?
Eye drops and medicine are used to treat glaucoma initially. Surgery may be necessary if the blockage in the drainage system cannot be removed in other ways. Your optometrist will refer you to an eye specialist for treatment if they consider you have glaucoma.
Can glaucoma be prevented?
No. Early detection and treatment is the best way to control glaucoma.
Who is likely to be affected by glaucoma?
People over the age of 40 years are far more likely to have glaucoma than younger people. Also, glaucoma tends to run in families. People with a blood relative who has suffered from glaucoma and people over 40 years of age are at risk and should have their eyes checked regularly by an optometrist.
Cataracts
What are cataracts?
Cataracts are a cloudy areas that form in the lens of the eye. The lens is normally clear. 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.
Normal eye, with no cataract. Light is focused on the retina.
Eye with cataract. Light is scattered, causing blurred, hazy vision.
Are cataracts a kind of growth?
No. Cataracts are due to a change in the lens material. However cataracts can become worse as more of the lens material changes.
What causes cataracts?
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.
Do cataracts get worse?
Yes. The clouded areas become larger and denser and cause the patient's sight to become worse. The time taken for this to happen varies from a few months to many years.
Do cataracts affect both eyes?
Usually cataracts affect both eyes but often develop at different rates in each eye.
How common are cataracts?
People older than 65 years often have signs of cataracts and should have their eyes examined regularly. However the extent of the cataract varies considerably between individuals of the same age.
Can cataracts cause blindness?
If untreated, cataracts can cause blindness. Blindness can be prevented by detecting the cataracts early and, if necessary, by having them removed surgically. Your optometrist will refer you to an eye specialist if they consider that you need medical treatment for your cataracts.
How well will I see if my lens is removed?
In most cases very well. Most patients have an intra-ocular lens (IOL) inserted at the time of surgery, with excellent results. This is a plastic lens which replaces your own cloudy lens. Patients may also need to wear spectacles or contact lenses.
What are the signs of cataracts?
Usually the development of cataracts is gradual with a painless worsening of sight. Other symptoms include blurred or hazy vision, spots before the eyes, double vision and a marked increase in sensitivity to glare.
How can I be sure I don't have cataracts?
An examination by your optometrist will reveal any changes that have occurred in the lens of the eye. Optometrists have special equipment which enables them to see changes in the lens which may lead to cataracts several years before any symptoms appear.
Can cataracts be prevented?
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.
When should I have a cataract operation?
This varies with each patient. Usually cataract surgery is performed when the patient's vision interferes with daily life. Your optometrist will assist you in making this decision.
Is cataract removal a major operation?
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.
Age-related macular degeneration
What is age-related maculopathy?
Age-related maculopathy (ARM), also known as senile macular degeneration, is damage or breakdown of the macula. The macula is a very small part of the retina, the light-sensitive tissue of the eye, which is responsible for central vision. This is the part of the retina which produces the finest detailed vision.
How does ARM affect vision?
As ARM damages the part of the retina responsible for central vision and for seeing fine detail, it becomes difficult to see small details of objects. Vision to the sides is not affected. If both eyes are affected, reading and other tasks requiring fine vision may become very difficult. ARM does not cause blindness. Because some side vision remains, usually people can still take care of themselves.
What causes ARM?
ARM 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 per cent 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 blocks out central vision to a severe degree. There are also some other forms of macular degeneration which are inherited and not associated with ageing.
How common is ARM?
ARM mainly affects older people: about four per cent of those more than 40 years old, nine per cent of those over 50 years, 23 per cent of those over 65 years and 31 per cent of those aged 80 years or more. Men and women are equally affected. ARM accounts for up to 45 per cent of legal blindness and up to 70 per cent of seriously impaired vision in people over the age of 70 years.
How is ARM detected and diagnosed?
People with ARM may notice that their vision has deteriorated. Many patients do not realise that they have a problem until their vision becomes blurred. Optometrists perform a number of tests in an examination which enables them to detect the presence of ARM in the early stages.
The optometrist examines the macula carefully with an instrument called an ophthalmoscope which allows examination of the interior of the eye. Sometimes the optometrist may place a drop in the eye to dilate the pupil to get a better view of the internal structures. Through the ophthalmoscope the optometrist will look for changes in the structure of the macula such as accumulations of waste material or new blood vessels.
Another test which may be used is a grid pattern known as an Amsler chart. This is a regular grid which looks like a piece of graph paper. Patients with ARM often report that sections of the grid appear to be distorted or missing.
Optometrists will usually refer patients whom they suspect have ARM to an ophthalmologist (eye surgeon) for confirmation of the diagnosis. The ophthalmologist may perform a test called fluorescein angiography. In this test a fluorescent dye is injected into the patient's bloodstream and the ophthalmologist observes the progress of the dye through the blood vessels in the retina. This reveals any leaking blood vessels.
Can ARM be treated?
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, compared with other vision disorders. For example, it is possible to remove and replace the eye's lens in a person with cataract but it is not possible to replace or even repair the retina of a person with ARM.
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.
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 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 spectacles, hand-held and stand magnifiers, closed circuit televisions and other simpler aids such as large-print books.
What should you do about ARM?
For treatment of ARM to be effective, it must be diagnosed as early as possible. Regular eye examinations 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 examinations are particularly important for people over the age of 50 years and people whose families have a history of eye problems.
Pterygium
What is a pterygium?
A pterygium (pronounced te-ri-gi-um, plural: pterygia) is a triangular-shaped lump of tissue which grows from the conjunctiva (the thin membrane which covers the white of the eye) on to the cornea (the clear central part of the eye). Pterygia often occur in both eyes, usually on the side of the eye closer to the nose. A pterygium is not a cancer. People sometimes confuse pterygia with cataracts. A cataract is a clouding of the lens inside the eye and cannot be seen easily with the naked eye.
What causes pterygia?
The exact causes of pterygia are not known, but they are strongly associated with exposure to ultraviolet radiation and hot, dry environments. Pterygia are more common in the Northern parts of Australia and among people such as farmers and surfers who spend a lot of time outdoors, but anyone can develop a pterygium.
Are pterygia dangerous?
Pterygia are not dangerous, although they can look ugly and cause some discomfort. The main problem with pterygia is that as they grow on the cornea they distort it, interfering with vision. If the pterygium grows on to the central part of the cornea it can begin to block light from entering the eye.
Although a pterygium is not dangerous, it should be checked to make sure that it is not something more serious. If you have any area of tissue on or around the eyes that changes rapidly you should consult an optometrist or eye surgeon (ophthalmologist) immediately.
How can pterygia be treated?
In cases where the pterygium is not actively growing on to the cornea, protecting the eyes from ultraviolet light often will stabilise its growth. In many cases, provided it is not threatening vision and it remains stable, this may be all that is required.
In cases where the pterygium is actively growing on to the cornea and threatening to distort the vision, the only effective treatment is surgical removal. Fortunately this is relatively minor surgery which usually is performed under a local anaesthetic. It is best to have surgery before the pterygium progresses to the point where it interferes with vision. Your optometrist can assess the pterygium and refer you to an eye surgeon if it requires removal.
How can pterygia be prevented?
The best way to reduce your risk of developing a pterygium is to protect your eyes from ultraviolet light. UV radiation can also cause cataracts and other eye diseases, as well as skin cancers, so reducing exposure is a wise move. The best ways of doing this are to:
· Avoid the sun: in summer, three-quarters of outdoors UV exposure occurs between 10 am and 4 pm. Staying out of the sun between those times will significantly reduce your UV exposure.
· Wear a hat: a broad-brimmed hat will not only protect your head from sunburn, but will reduce by at least half the amount of UV radiation reaching your eyes.
· Wear sunglasses: a good pair of sunglasses will reduce the amount of UV reaching your eyes and cut the amount of glare. Wrap-around sunglasses are best as they block UV radiation which can slip around the sides of conventional sunglasses.