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Cataract: The Commonest Cause of Blindness in the World By Murtala Umar
The World Health Organization (WHO) estimates that about 30 million people in the world are blind, 29 million of these living in developing countries. Cataract, a treatable disease, is said to be responsible for half of the blindness. Cataract simply refers to a condition in which the lens in the human eye becomes opaque or cloudy. The eye is a specialized organ that is modified to allow vision. The lens of the eye, normally as transparent as clear glass, begins to grow cloudy, fogging over and preventing the light from the images in our world, to pass through the lens and strike the back of the eye (retina) where the light can be transformed into electrical impulses that pass on to the brain.
The prevalence of cataract is very high in the world especially in the resource poor countries. Couching is an old traditional treatment for thousands of year and still popular in Northern Nigeria. The merits and demerits of couching shall be discussed later. A summary of a study in a rural community in Northern Nigeria by a group of Doctors from National Eye Center Kaduna x-rays the picture of cataract in the region; A population based cross sectional survey was conducted to determine the magnitude of cataract blindness and the barriers to uptake of cataract services in a rural community of northern Nigeria. METHODS: 1461 people out of 1924 registered eligible people were examined. The study population was chosen by two stage cluster random sampling. In the first sampling stage 15 villages were randomly chosen while in the final stage 170 people who were 40 years and over were selected in each village. Each selected person had visual acuity recorded for both eyes. Those with vision of less than 3/60(read at 3 meters what a normal person could read from 60 metres) in the better eye were assessed for cataract. People with cataract were asked why they had not sought medical attention. RESULTS: A blindness prevalence of 8.2% (95% CI 5.8%-10.5%) was found among the sampled population. Cataract was responsible for 44.2% of the blindness. Thus, a cataract blindness prevalence of 3.6% was found. The cataract surgical coverage (people) was 4.0% and the couching coverage (people) was 18%. The main barrier to seeking cataract surgery was cost of the service (61%). CONCLUSION: Some regions of the world still have high burden of cataract blindness that needs attention. Such areas need an effective free cataract outreach programme
The causes of cataract cannot be exhausted in this small piece the end result however, is a physical and or chemical change resulting in lens opacity. Age related cataract is by far the commonest type. . The lens normally is a clear structure that permits the light to pass through, and helps to focus the light onto the retina in the back of the eye, permitting a clear image to form. The lens has an inner nuclear area, and an outer portion called the lens cortex. Both these elements are contained within a capsule, and any one of these three components may lose their transparency. In most cases, cataracts due to aging occur in the nucleus and cortex, while those that develop as the result of diabetes or the use of corticosteroids are found under the capsule on the back side of the lens. Of course injuries can cause opacities in any portion of the lens. Children could have the disease at birth especially of mothers who suffered from Rubella virus infection at the first three months of pregnancy. The symptoms patients present with depend on the extent and position of the lens opacity. It could range from no symptom at all, to poor vision terminating as blindness. Depending on the cause of the disease, presentation may be on one or both eyes.
The good thing about cataract unlike Glaucoma (an eye disease that cause irreversible blindness), is a treatable disease. Over 90% of patients regain their vision following modern surgery. . Once the cloudy lens is removed sight is restored, and the use of special glasses can bring vision back to near normal. Contact lenses may sometimes be used as well. In some cases the surgeon will position a new, artificial lens (intraocular lens or IOL) to replace the damaged one that was removed. The operation is carried out in about 20 minutes.
The primary prevention of cataract is still under study since it is mostly an aging disease. The use of Aspirin and vitamin c are speculated to delay the onset of cataract formation but not yet proven. Probably the best way we know of right now to slow cataract growth is to protect your eyes from overexposure to the sun. People who are in intense sun for long periods of time with no eye protection seem to develop cataracts more frequently. Wear sunglasses that are marked as UV-A blockers or have your optometrist make up prescription UV blockers. Diabetics can prevent cataract by complying with their medication and regular clinical visits to ensure sugar control. Also regular ante natal care attendance by pregnant women would allow the early detection of infection(s) that predisposes the foetus to developing cataract.
Secondary prevention where the disease has occurred should be the goal in order to prevent blindness. We have a duty to mobilize our relatives, friends, neighbors etc suffering from poor vision or blindness, to the hospitals for proper evaluation. The cost of surgery had hitherto been prohibitive but a lot of effort by various Governments and NGOs are cushioning this effect. There is need to train more health workers to perform the operation and open camps in rural areas to provide free or highly subsidized surgery. You and I have a responsibility to help people blind from cataract to regain their vision. Parents must rush their babies to the nearest hospital on suspicion of any visual defects.
It is true that couchers provide affordable and accessible cataract treatment in the community the procedure however, does more harm than good. Because the couchers introduce a needle to displace the cloudy lens from the visual path way, the patient is able to see. Readers will however agree with me that the lens left floating in an unnatural anatomical position is capable of damaging the eye, a very delicate organ. This could lead to a battery of complications with end result been irreversible blindness in future. This is not to say that modern surgery is not without complications, but the fact that lens is removed and replace with an artificial one, reverses the condition to near normal. Couching is therefore medically unsafe and should be discouraged.
Cataract has rendered so many people blind despite availability of modern treatment. It is pertinent for the Governments, philanthropists, NGOs etc to partner with international organizations like Sight Savers International and Christian Blind Mission to prevent this preventable cause of blindness. We must also not forget to rehabilitate people already blind from the disease by providing special education and vocational training.
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