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13 April 2011

Sight of sore eyes

Have you ever wondered what the world looks like through the eyes of someone who has glaucoma, a cataract or other vision problems?

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Have you ever wondered what the world looks like through the eyes of someone who has glaucoma, a cataract or other vision problems? This will give you some insight

Normal 20/20 vision

What do images look like?
Everything is sharp and in focus. There are no blurred edges when you look at objects close to you or far away.

Why?
The lens of the eye focuses the light rays exactly on the retina at the back of the eyeball. The eye is like a digital camera on autofocus - just more sophisticated. The eye muscles, cornea and lens continuously adjust, allowing the image you're looking at to focus precisely onto your retina.

Near-sightedness

What do images look like?
Objects close by are clear and in focus but everything far away looks blurred and hazy.

Why?
If the eyeball is too wide (like a ball being squeezed from the top and bottom), mainly because of genetic factors, or if the cornea is too curved, light rays focus on a point in front of the retina instead of on the retina itself.

Some people even struggle to see objects right in front of them clearly.

How many people are affected?
It's very common: one in three people are affected.

How can it be corrected?
With glasses or contact lenses. Laser surgery can enable people with a low degree of near-sightedness to stop using their spectacles or contact lenses while people who are badly near-sighted may afterwards be less dependent on them.

Laser surgery can be done only once the condition has stabilised, usually after the age of 18.

Presbyopia

What do images look like?
Objects that are close, such as the text in a magazine, are out of focus. They look like the images of far-sightedness (right). The afflicted person has to hold the text further away to read it.

When the person looks up he initially finds it difficult to focus on distant objects.

Why?
After the age of 40 the lens of the eye becomes more rigid and less elastic.

How many people are affected?
Almost all people need reading glasses as they grow older. Even people over 40 find it more difficult to read or see properly when they're tired. Your eyes may continue to get weaker until you are well into your sixties, after which the condition stabilises.

How can it be corrected?
With reading glasses. You can buy a pair at your pharmacy but have your eyes tested by an optician in case you have other problems.

Far-sightedness

What do images look like?
Far-sightedness is the opposite of nearsightedness; everything far away is clear and in focus but objects close by are blurred and hazy.

In extreme cases both close objects and distant ones may be out of focus.

Why?
If the eyeball is too fl at (like a ball being squeezed from the front and the back) light rays are focused behind the retina instead of directly on the retina.

How many people are affected?
About 10 million people in South Africa. The condition is often diagnosed even before a child goes to school.

The eyes of children born with a degree of far-sightedness may tire more easily and they may develop headaches if they read a lot. Far-sightedness can cause a squint.

How can it be corrected?
With glasses or contact lenses. Laser surgery may be helpful in some cases.

Astigmatism

What do images look like?
Everything, far away and close by, looks slightly out of focus. It's difficult to see fine details clearly. Usually one side is more out of focus than the other.

Sometimes it seems as if vertical lines are leaning to one side like the Tower of Pisa.

Why?
Light is focused on more than one point on the retina because the shape of the cornea is uneven. Some people are born like that.

Instead of being round like a soccer ball the retina has a slightly oval shape - more like a rugby ball.

How many people are affected?
About three in 10 people have a degree of astigmatism. Most don't even notice it. However, your eyes tire easily and you may get headaches.

People who are near-sighted or far-sighted often also have astigmatism. Astigmatism never really gets better or worse.

How can it be corrected?
With glasses or contacts. Laser surgery can repair mild cases.

Glaucoma

What do images look like?
Images in the middle of the field of vision are clear and focused but everything around it is out of focus. Sometimes there are coloured halos around bright lights.

It creeps up on you like a thief in the night and gradually and surreptitiously robs you of your sight. The outer circle, which is out of focus, keeps getting larger and the small middle section, which is in focus, gets smaller until you're left with tunnel vision.

This may eventually lead to blindness. The eye also struggles to adjust from lighter to darker surroundings.

Why?
For genetic reasons excess fluid builds up inside the eyeball and causes abnormally high levels of pressure. This pressure damages the optic nerve at the back of the eye.

How many people are affected?
About five per cent of South Africans. It's five times more prevalent among black people than in other population groups.

The risk of glaucoma increases with age. Diabetics, people with high blood pressure and those with eye injuries have a greater chance of getting this disease. It's also more common among near-sighted people.

It's important to diagnose glaucoma early because damage to the optic nerve, should it occur, can't be repaired. People who are older than 50, who have a family history of glaucoma, who suffer from severe near-sightedness or suffered a serious injury to the eye should visit an ophthalmologist once a year.

How can it be corrected?
Eye drops are prescribed to relieve the pressure. Patients must use these drops every day for the rest of their lives. Sometimes surgery is used if drops can't sufficiently relieve the pressure.

Note: People who suddenly experience severe pain inside an already reddening eye need to go to the doctor immediately - especially if this condition is accompanied by blurred vision and nausea.

It could indicate an acute and dangerous form of glaucoma which may cause permanent loss of sight.

Macular degeneration

What do images look like?
Sufferers see dark spots or grey areas in the middle of their field of vision. It makes it more difficult to read and later to recognise faces.

Straight lines such as doorposts and telephone poles start looking twisted and objects appear smaller and further away than they really are. Sufferers can, however, still see images on the peripheries of their field of vision quite clearly.

This condition usually starts in one eye then spreads to the other.

Why?
The macula is the part of the retina responsible for the sharp, central vision used for reading, observing fine detail and driving. If, due to old age, the macula becomes damaged you lose your central vision.

It may happen unexpectedly. People over 60, whites, those with a family history of the disease and smokers run the greatest risk of contracting the disease.

One of the forms of the disease, which affects young people, is usually diagnosed during the toddler stage or when a child starts school and has a strong genetic factor.

How many people are affected?
Nearly 1,6 million South Africans. Macular degeneration is the greatest cause of blindness among people over 60.

According to international experts these figures will treble over the next 25 years. It is also found more and more frequently among young people.

How can it be corrected?
Damage that has already occurred can't be repaired. In the early stages laser surgery can help to delay loss of vision.

Giving up smoking, eating foods containing lots of lutein and antioxidants (such as dark, leafy vegetables) and taking zinc supplements can delay the onset of the disease.

Laser surgery is sometimes helpful and direct injections into the eye appear to be promising.

Cataracts:

What do images look like?
Slowly but surely your vision becomes more and more blurred. It's like looking through a dirty camera lens.

Colours become increasingly dull and it's more difficult to distinguish between colours and lighter and darker areas. Night driving also becomes more difficult because of a halo around the headlights of oncoming traffic. Some people also experience double vision.

People with cataracts find they need more light for reading as well as stronger reading glasses.

Why?
Lens protein is normally clear but when it starts lumping together it becomes opaque and the lens becomes murky.

Some cataracts get worse in a matter of weeks while others may remain unchanged for a long time.

About three-quarters of all cataracts are caused by ageing. The rest develop because of diabetes, genetic factors or eye injuries. If a woman contracts German measles during pregnancy the baby may be born with cataracts.

How many people are affected?
About 900 000 South Africans. Cataracts are quite common among people over 60.

How can it be corrected?
Surgery is the only effective treatment. The cloudy lens is removed and replaced with a new plastic lens.

The removal of a cataract remains a personal decision. Some people are quite happy to live with a cataract and reduced vision while others find it extremely disruptive.

If your quality of life starts suffering - if, for example, you can't drive any more - it's usually time to have the cataract removed.

Retinitis pimentosa

What do images look like?
Progressively worsening night blindness and several dark spots in the field of vision are early signs.

Years or even decades later you will experience tunnel vision. The centre of your field of vision initially remains unaffected but also gradually disappears.

Why?
The photoreceptor cells in the retina are slowly dying.

How many people are affected?
About 17 000 South Africans. Retinitis pigmentosa is a hereditary disease and people who have a family history of the disease are at considerable risk of getting it.

How can it be corrected?
There is no treatment for the disease as yet.

Retina South Africa is doing breakthrough research on the genes causing retinal degeneration in South African families. Their research project is investigating the causes, possible treatment and medicines for vision problems such as macular degeneration, near-sightedness, retinitis pigmentosa, diabetic retinopathy and other diseases connected to the retina.

Go to www.rpsa.co.za for more information on the latest research.

Diabetic retinopathy

What do images look like?
Often there are no early warning signs. As time passes the sufferer develops night blindness.

Images become unfocused and a dark spot develops in the middle of the field of vision with fl oaters or "cobwebs" seemingly drifting around.

Diabetic retinopathy can lead to serious loss of sight and even blindness if it's not treated early enough. It's therefore essential that diabetics visit an ophthalmologist once a year.

Why?
It's caused by abnormal changes in the blood vessels of the retina.

How many people are affected?
Almost all patients with type 1 diabetes and 70 per cent of those with type 2 diabetes will develop this condition.

As many as 21 per cent of type 2 diabetics already have a measure of eye damage by the time they're diagnosed with the disease.

How can it be corrected?
By means of laser therapy, injections into the eye and even the replacement of eye moisture.

But prevention is best so good diabetic control is essential.

Did you know?
Men are 10 times more likely to suffer from colour blindness.

Have your child's eyes tested at the following ages:

1 or as soon as he starts talking if you suspect there might be a problem.

6 Have it done along with school readiness tests.

12 A thorough eye test should be done before he goes to high school.

Do you spend hours in front of a computer?
Give your eyes a break every 15 minutes by looking into the distance.

It's an emergency!
• A scratch, cut or anything that penetrates the eye
• Sore and/or red eye(s), with or without nausea
• Sudden loss of vision

Many cases of vision problems are congenital (present at birth) and others develop as a result of ageing.

Eye injuries can also lead to blindness. It's a myth that reading in poor light or sitting too close to the TV can cause eye problems or make things worse.

Constantly staring at a computer screen, however, can make your eyes tired.

Do you see floaters?
Floaters are specks that drift across your field of vision. The problem is caused by small particles in the transparent jelly-like fluid that fills your eye.

Floaters are mostly harmless but contact your doctor within 24 hours if they suddenly increase, if you see fl ashes of light or if it looks as if a curtain is coming down over your field of vision.

It could be a retinal tear or a detached retina, both serious problems.

This story originally appeared in the first edition of Pulse magazine. Buy the latest copy, on newsstand now, for more fascinating stories in the world of health and wellness.

YOU Pulse; Spring, September 2007

- updated April 2011

 
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