Diseases of the Eye

What is Macular Degeneration (MD)?

What is Macular Degeneration (MD)?

Macular degeneration (MD), also known as age-related maculopathy or 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 that is used for the finest detailed vision.

How does MD affect vision?

MD damages the part of the retina responsible for central vision and for seeing fine detail, and makes it difficult to see small details of objects. Side vision is not affected. If both eyes are affected, reading and other tasks requiring fine vision may become very difficult, but because side vision remains, people with MD can usually take care of themselves.

What causes MD?

MD 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 (neovascular) vessels are fragile and often leak blood into the retina, where the blood causes scar tissue to form. The scarring severely blocks central vision. Other forms of macular degeneration are inherited and not associated with ageing.

How common is MD?

Macular degeneration is the major cause of vision impairment and blindness in Australia for people over the age of 50. Early MD occurs in about 14% of those aged 55 to 64 years, 18% of those aged 65 to 74 years, and 30% of those aged over 75 years. Men and women are equally affected. MD accounts for almost 50% of legal blindness and up to 70% of seriously impaired vision in people over the age of 70 years.

How is MD detected and diagnosed?

People with MD may notice that they can no longer read as quickly as previously even with their reading glasses, or they may notice that their vision has deteriorated. Many patients do not realize that they have a problem until their vision becomes blurred. Optometrists perform a number of tests in an examination, which enable them to detect the presence of MD in the early stages.

The optometrist examines the macula carefully with a range of specialized instruments such as an ophthalmoscope, retinal camera or slit-lamp with a high-powered lens.  These instruments allow examination of the interior of the eye, including the macula. 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 macula, such as accumulation of waste material or new blood vessels.

Another test that may be used is a grid pattern known as an Amsler chart. This is a regular grid that looks like a piece of graph paper. Patients with MD often report that sections of the grid appear to be distorted or missing.

Optometrists will usually refer patients whom they suspect have MD 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 MD be treated?

Recent advances in treatment of the early stages of neovascular MD involve injection of anti-VEGF (vascular endothelial growth factor) substances that prevent the formation and growth of abnormal blood vessels. This is the first treatment of MD that has been shown to improve vision in some cases but complete or permanent resolution of abnormal blood vessels is not possible. The treatment needs to be repeated as part of ongoing management of the disease. Associated risks of anti-VEGF treatment include formation of cataract and ocular inflammation.

Photodynamic therapy (PDT) is a well-established treatment for vascular forms of MD. Laser surgery may be used where new blood vessels have appeared in the macula area. A focused, intense beam of laser light is used to seal leaking blood vessels and 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 is little that can be done to cure MD, particularly in its more advanced stages. One study found that antioxidant vitamin and mineral supplementation assisted in halting the progression of MD in a small percentage of patients. These supplements should be taken under the supervision of a health care professional as they may be associated with harmful effects.

People with MD can be helped to continue functioning normally. Many will eventually be classified as having low vision. 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 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 MD?

For treatment of MD 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. Other important preventative measures include minimizing exposure to UV light and cigarette smoke, both of which are associated with MD. A low-fat diet rich in green leafy vegetables, nuts and fish may be beneficial in reducing the impact of MD.

What is Blepharitis?

Chronic inflammation of the eyelids is called blepharitis. It is a common eye disorder which causes irritation, burning sensations, itching, light sensitivity and redness. It is often at is worst upon awakening.

Blepharitis can cause scaling and crusting around the eye lashes or the secretion of an oily substance from the meibomiam gland (the gland which produces lubricant that discharges from tiny openings on the edges of the eye lids).

There is no cure for blepharitis but with treatment, it can be kept under control. Treatments for blepharitis usually includes eye drops, careful cleansing of the eyelids and warm compresses.

What are Cataracts?

Cataracts are 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.

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 due to 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 they 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 anesthetic. 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 specializes in eye surgery. Your optometrist will refer you to an ophthalmologist if necessary.

How Can Diabetes Affect Your Eyes?

About 7% of the Australian population over 25 years of age have diabetes, increasing to about 24% of people over 75 years of age. Of these, more than 70% will develop some changes in their eyes within 15 years of diagnosis. Optometrists play a fundamental role in diagnosing these conditions in their early stages when they respond best to treatment.

Eye changes in people with Diabetes

Diabetes sometimes causes the focusing ability of the eye to weaken or to fluctuate from day to day. This characteristic has often led to optometrists diagnosing diabetes in their patients. The problem eases when blood glucose levels are well controlled. Diabetes can also cause more dangerous changes in the eyes, primarily through its effects on the blood vessels in the retina.

Diabetic Retinopathy

After diabetes has been present for some years, changes may occur at the back of the eye in the retina. Your optometrist uses an instrument called an ophthalmoscope to check for these changes. These changes are known as diabetic retinopathy. There are two main types of this condition: Non-proliferative (sometimes called background) retinopathy and proliferative retinopathy. The risk of developing retinopathy increases with the length of time you have had diabetes. The risk is also increased when blood glucose levels are not well controlled over time.

Non-proliferative Retinopathy

This condition rarely causes any vision to be lost and therefore does not require treatment. Occasionally a swelling of the retina may cause hazy vision or straight lines to appear bent. Your optometrist may instruct you in a simple procedure to carry out at home so that you can test your eyes for this condition. If vision is affected in this way your optometrist can confirm its cause and will refer you for appropriate treatment.

Proliferative Retinopathy

This condition is more serious and requires early treatment to prevent serious vision loss. Your optometrist can recognize signs that this condition might develop, or detect it in its early stages. Once proliferative retinopathy has been diagnosed, your optometrist will refer you to an eye surgeon for further appraisal and probable laser treatment. Treatment of this condition has a better chance of success if it is applied very early.

Managing Diabetic Retinopathy

Controlling blood glucose over time significantly reduces the risk of developing retinopathy, but does not eliminate it. The best management is to have regular eye examinations so that changes can be detected and treated early. It is advisable for all people with diabetes to have yearly eye examinations. People who have been diagnosed as having retinopathy should have eye examinations more frequently than once a year. In addition, regular visits to the general medical practitioner and/or the endocrinologist may help to control blood glucose levels.

Double vision

This is a distressing but rare complication of diabetes. The condition is usually temporary but it may last for a few months. An optometrist can help treat it while it has effect. Diabetes is not the only cause of double vision.

 

What are Floaters?

Floaters are relatively transparent, vague, usually curves objects that are seen best when looking at a white piece of paper, blue sky, light coloured ceiling, or wall. They sometimes look like cobwebs, worms, rings, dots, or specks. Eye movement makes floaters more visible as they swirl about like seaweed in the ocean surf.

What is the most common cause of Floaters?

They are usually cause by a clumping of pre-existing vitreous fibers in the eye. Therefore, vision care professionals usually refer to them as vitreous condensations. 

What are some of the other causes?

Some floaters are red blood cells or blood clots on the surface of the retina or floating in the vitreous. Such blood cells may occur with some retinal tears but do not necessarily indicate a tear. Occasionally, the vitreous can pull on a blood vessel on the surface of the retina and cause bleeding without causing a tear of the retina. Vascular disorders such as diabetic retinopathy and vein occlusion frequently result in bleeding inside the eye. Rarely, floaters may be inflammatory in origin. Diseases such as pars planitis and uveitis can cause the formation of clumps of white blood cells (cells that the body produces when there is inflammation). Floaters can also appear after a YAG laser capsule opening procedure (capsulotomy). After almost 50% of cataract surgery procedures that involve the implantation of intra-ocular lenses, the layer of tissue behind this lens becomes cloudy, causing a decrease in vision. The YAG laser capsule opening procedure is performed in these cases to place an opening in this “lens capsule”, which usually results in better vision, but can also cause floaters.

Can Floaters cause total blindness?

Floaters do not cause total blindness, only a slight blockage of the vision at worst. Floaters are usually not detectable by visual testing unless they are very severe. Importantly, floaters can be related to retinal detachment or a variety of vascular conditions such as diabetic retinopathy, which can result in blindness if not treated. It is important to have any new incidence of floaters checked by your optometrist.

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 fibers 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 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 are 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.