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Diseases of the lens

What is a Cataract?

A cataract is any opacity of the normally clear ocular lens. Occurring in varying degrees and forms, cataracts commonly cause blurred or hazy vision, double vision or troublesome glare at night

Cataracts may be caused by a multitude of conditions including eye diseases, systemic diseases, heredity and trauma, but by far the majority occur as part of the normal ageing process in people above the age of 55 years. There is no known method of preventing or reversing cataract formation


Cataracts are diagnosed through comprehensive ophthalmic examination and are not to be confused with the more obvious superficial growth on the eye surface, the so-called pterygium


Cataracts are usually slowly progressive and surgical removal is the only treatment and is recommended once normal daily activities are impaired

What does Cataract Surgery involve?

Microsurgical removal of the cataract is done under general or, more often, a local anaesthetic. The cataract is removed via a small incision using ultrasound (SONAR) or mechanical instrumentation. An artificial lens is normally implanted and the incision may be closed with very delicate sutures, which may or may not be removed in time. Currently, the latest techniques requiring no sutures, are preferred whenever possible.


Pre- and Postoperative Instructions


  • Optimal general condition pre-operatively is important. Any infection (of the eye, bladder, and respiratory tract) or septic wounds pose a risk to the operated eye and should first be treated. Systemic conditions such as diabetes, hypertension, heart failure and asthma should be well controlled. A timely visit to your general practitioner a week in advance of surgery is advisable.
  • Please discontinue all eye cosmetics and contact lenses 72 hours prior to surgery. Anticoagulants (e.g. Disprin, Warfarin) should not be discontinued, but coagulation status should be monitored and optimised.
  • The eye drops prescribed after the operation should be instilled by pulling the lower lid away from the eye as follows: One drop 4 hourly for seven days and as directed thereafter only during waking hours (06:00-22:00).
  • Wash hands with soap and water before administering drops. Do not buy additional drops unless prescribed. The eye may be left open indoors, but protect with an eye pad from windy and dusty conditions and cover with a plastic eye shield during sleep for the first week.
  • Prevent water from entering the eye for the first week. (Do not swim or shower)
  • Pain tablets are only for the first two days after the operation. Any subsequent lasting PAIN, REDNESS or DIMMING of VISION should be reported to your ophthalmologist promptly. This is most important.
  • Acquisition of glasses will be arranged during the last post-operative visit.
  • Occasionally, vision may dim slowly weeks to years after the operation. It may be necessary to clear opacification of residual lens membrane with laser as an outpatient procedure requiring only a few minutes and no anaesthetic.

Common Eye
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the lens

Optic Nerve


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Common Optical Terminology