Sooner or later it comes to us all: cataract. The natural crystalline lens in our eyes becomes opaque and our visual acuity deteriorates. Cataract is primarily observed in the elderly where it is referred to as senile cataract. Cataract, however, is also a phenomenon witnessed in younger people and can even be congenital.
- The natural lens
- Cataract
- Symptoms
- Senile cataract
- Cataract caused by a disorder/an accident
- Congenital cataract
The natural lens
The natural lens, like the cornea, makes sure that the light rays which enter the eye are refracted. This results in a sharp image on the retina. The lens has a diameter of about 9 mm, is 5 mm thick and has a convex front and rear side.
The lens is clear and transparent which enables light to pass through it easily.
The natural lens consists of several elements:
- The lens capsule, an elastic membrane enveloping the lens,
- The cortex, the outer shell
- The nucleus
Cataract
In the young, the lens is clear and transparent. Lens opacity caused by old age or other reasons affects the clarity and the visual acuity. This is a cataract. Cataract is the most common cause of vision impairment and blindness in the world.
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A cataractous lens that is not treated and turns totally opaque and white is referred to as a ripe cataract. Patients can only make out the difference between light and dark. The lens may turn even more yellow or turn totally black, like the natural crystalline lens shown in this photograph. This type of ripe cataract is still observed in the developing countries. |
Cataract may originate in various different locations in the lens. Its onset may be in the middle of the lens, on the side or in other positions. Cataract usually starts out in the middle of the lens, in which case it is referred to as nuclear cataract.
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A cataractous eye. The opaque lens is visible through the pupil. |
Symptoms of cataract
The most common symptoms of cataract are:
blurred vision, fewer details
- double vision
- sensitivity to light
- the need for more light when reading
- diminished night vision
- changed prescription power for glasses
If you recognize one or more of these symptoms, you would be wise to make an appointment with your optician or ophthalmologist. By means of a slit lamp examination, they will be able to determine whether or not you are suffering from cataract. Any relevant treatment may subsequently be discussed.
Senile cataract
Senile cataract is by far the most common type of cataract. Senile cataract can be compared to getting wrinkles and turning grey. Due to an aging population, this type of cataract is on the increase.
Cataract caused by a disorder or an accident
Cataract can also occur in young people. In this case, it is usually caused by trauma, for instance when a foreign object gets lodged in the eye or by a blow to the eye. Other causes which may lead to the development of cataract in younger individuals are:
- diabetes;
- a surgical treatment of the eye (vitrectomy)
- long-term exposure to ultraviolet light, sunlight
- long-term use of certain types of medication, such as cortisone
- heavy smoking
- heavy drinking
Congenital cataract
In rare cases, cataract can be congenital. There may be a number of causes for this. Congenital cataract may occur because the mother had rubella during pregnancy. Other problems during pregnancy can also cause cataract. Sometimes congenital cataract is an independent problem, but it can also be part of another syndrome.
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Ophthalmologist Prof Dr. Jan Worst, husband of the founder of Ophtec, Anneke Worst, has made a major contribution to the development of artificial lenses. Pictured here with other pioneers of the artificial lens, among others, Sir Harold Ridley, (fourth person from the right), behind him to the left, Prof. Jan Worst and his Dutch colleague, Cornelius Binkhorst (third person from the left) |
