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What Is A Cataract?
A cataract is a clouding of the eye’s lens which eventually prevents light from reaching the retina, resulting in blindness. Usually, cataracts develop late in life, but they can be present in babies or may stem from injury to the eye or eye diseases (including inflammatory conditions). The cataract itself is caused by changes taking place within protein present in the eye’s lens (denaturing) which gradually cause it to become progressively opaque.
There are some 45 million blind people in the world and approximately 314 million people suffer from significant visual impairment; 85% of these come from poor and middle income countries. According to the World Health Organisation, age-related cataracts are responsible for approximately 48% of blindness in the world. They estimate that the problem affects some 18 million people.
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Incidence In The Developed World And Treatment
The good news is that cataracts can be cured by a relatively simple surgical procedure which involves replacing the damaged lens with an artificial, intra ocular lens. The procedure is the most common surgical intervention in people over the age of 65 in the western world. It is estimated that a third of the population over 65 will develop cataracts although not all will become serious enough to require surgery. Restoration of sight following cataract removal will usually occur within a week of the operation, once the trauma to the eye has resolved. Whilst the operation is very successful at restoring the sight of a cataract sufferer, it is not available to many people in the developing world because of cost and the lack of an adequate medical infrastructure in many parts of the world.
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In the western world, complications from cataract removal are very rare, but some problems may arise. The complications from cataract removal can include infection (always a risk with any surgical intervention); double vision; intra ocular bleeding and loss of vision. Some specific complications that can arise from catact surgery are given below:
Retinal detachment can occur in approximately 0.5% of cataract surgeries.
Cystoid macular edema may occur post-operatively, due to seepage from blood vessels in the retina.
A vitrectomy (drainage of the vitreous humour from the eye) may be needed if fragments of the organic lens get into the cavity behind the membrane that surrounds the lens to remove the fragments and reduce swelling (the fluid will replace itself naturally).
Endophthalmitus is a post operative infection occurring within the eye. Antibiotic eye drops are given on the day of surgery to prevent infection, but this condition will occur with a frequency of approximately one incident per 3000 operations.
Choroidal haemorrhage affects the fine web of blood vessels supplying the retina and can occur during the procedure. Older patients and those with glaucoma or high blood pressure are at the greatest risk of suffering from this complication.
Secondary cataracts may occur years after surgery and develop on the back of the lens capsule. They can be treated very effectively by laser surgery.
The charity Sightsavers International carried out nearly 275000 cataract operations last year in developing countries. Donations can be made to support their work through their website.
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- World Health Organisation, Priority Eye Diseases: http://www.who.int/blindness/causes/priority/en/index1.html
- Website of Cataract.Com: http://www.cataract.com/
- Sightsavers International: http://www.sightsavers.org/our_work/default.html