Eye Health

Updated 16 January 2015

Why regular eye tests are important

It may surprise you to learn that you could be saved from serious illness by having your eyes tested more often.


It may surprise you to learn that you could be saved from serious illness by having your eyes tested more often. Regular examination of your eyes by a qualified optometrist may reveal changes in vision, monitor certain conditions of the eye and check for general health.  Eyes are sensitive indicators and show up health problems long before there are any obvious physical symptoms.  During an examination an optometrist can detect conditions such as high blood pressure, hypertension and excess cholesterol.

Furthermore, a full eye examination is important in the detection and control of diabetes. One of the first signs of this disease is erratic vision and a change in prescription - something which is quickly noticed by optometrists. Optometrists also check for other eye conditions, including cataracts, glaucoma, spots or floaters and colour deficiency.


Can any eye examination detect diabetes?

Yes. Certain changes around and inside the eye can cause an optometrist to suspect diabetes and send the patient for immediate tests. The blood vessels in the eye are very delicate and are often the first to be affected by diabetes. As these vessels can be viewed directly, your optometrist will be able to detect any diabetic related change.

Which vision defects indicate diabetes?

Fluctuating vision (good one day and poor the next) is a common symptom. Generally, diabetes may cause poorer distance vision, but improve close reading vision.

What special eye care must be taken by diabetics?

Good control over the blood sugar levels is vital. A regular (annual) optometric examination is of paramount importance in order to detect any changes in the eye.


The word ‘cataract’ refers to the total or partial cloudiness or opacity of the lens inside your eye. Cataracts can be very small, or large, causing obvious loss of vision. They are most common in people over 55 years of age, but sometimes occur in younger people and even in babies.

What causes a cataract?

Although no direct causal link has been established, age, heredity, disease or damage to the eye has been suggested as the trigger for the chemical change inside the eye which turns the lens cloudy. Both eyes are usually affected, but not at an identical rate.  At present no one knows how to prevent the formation of cataracts, but protecting the eyes from UV exposure is recommended.

What are the symptoms of cataract development?

Since no pain or redness is normally experienced with cataracts, symptoms to note are hazy/blurred vision or a ‘film over the eyes’, spots in front of the eyes or even a growing sensitivity to glare, particularly at night. Near vision may actually improve temporarily

What treatment is recommended for cataracts?

Although changes in spectacle lenses can help vision for a time, if the cataract develops to a stage where it affects normal active life, surgical removal is necessary. This fairly uncomplicated procedure is performed by a specialist eye surgeon and is at least 95% effective.


Glaucoma is a disease caused when fluid pressure builds up inside the eyeball, damaging the retina and optic nerve (which sends visual information to the brain).  Glaucoma is one of the leading causes of blindness.

What causes glaucoma?

It is not known precisely why the passages that allow the eyes’ fluid to drain, clog or block up, causing a rise in pressure and subsequent (permanent) nerve damage. Pressure can also rise due to infection, injury or tumor.

Are some people more prone to glaucoma?

Because glaucoma is most common in people over 40 years of age, regular, full eye examinations are essential for those 40 and older.  In addition a tendency to develop glaucoma runs in certain families, and short-sighted people and diabetics are more prone to develop glaucoma.

What are the symptoms of glaucoma?

There are two kinds of glaucoma:

  1. Primary open-angle glaucoma produces no pain and little noticeable disturbance in vision. Without warning, you may actually have lost some vision before any symptoms appear.
  2. Acute angle-closure glaucoma is caused by a sudden blockage of the eye’s drainage passages. Pressure builds up quickly, vision becomes blurred, lights appear to have coloured rings around them, and the eyes are painful and red.

How can glaucoma be detected and treated?

In a simple painless test, the optometrist puffs air against the eye and uses a tonometer to determine the internal pressure of the eye.  If diagnosed early enough, glaucoma can be controlled, resulting in little or no more loss of vision. If not treated, peripheral as well as central vision will be destroyed and blindness may result.


They are small semi-transparent or cloudy particles which are actually inside the eye. You only notice them when they fall in the line of sight. They appear in various shapes and sizes, as threads and ‘cobwebs’ and seem to dart away when you try to look at them. Practically everybody sees a few spots at sometime or the other and they become more obvious as you get older.

What causes spots?

Sometimes, before birth, tiny pieces of protein or other matter can become trapped inside the vitreous (jellylike) part of the inner eye. They can also be caused by eye disease, injury or problems in the eye fl uid or surrounding tissue.

Are spots dangerous?

In general spots are normal and seldom cause blindness, BUT spots can be a sign of more serious problems and a complete eye examination by a qualifi ed eye-care practitioner is necessary


Is colour deficiency ‘colour blindness’?

Colour deficiency means a lower than normal ability to distinguish colours and shades. Very few people are ‘colour blind’, i.e. unable to identify any colours at all. Colour deficiency is usually hereditary, but injury and conditions caused by side-effects of certain medicines can also impair the function of the colour-sensitive cone cells in the retina, which send the brain the correct colour signals. People are generally unaware of having any colour deficiency problem.

Which colour deficiency is most common?

An inability to distinguish between red and green is by far the most common colour deficiency, although there are several others.  Relatively simple tests can reveal which colour deficiency exists.

Should children be tested for colour deficiency?

It is vital that every child should be tested for colour deicifency before the age of five years. Colour coded learning aids are widely used in primary schools and much time may be lost in investigating learning difficulties which result simply from colour deficiency. Colour deficiency may also preclude certain career choices, e.g. pilot, electrician, policeman.



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Megan Goodman qualified as an optometrist from the University of Johannesburg and is currently practising at Tygerberg Academic Hospital in Cape Town. She has recently completed a Masters degree in Clinical Epidemiology at Stellenbosch University. She has a keen interest in ocular pathology and evidence based medicine as well as contact lenses.

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