Are intraocular lenses the solution to cataract blindness in Africa?

In 1994, the World Health Organisation estimated that there were 38 million blind people in the world. This total probably increases by another million every 12 months. The average prevalence of blindness is about 0.7%, ranging from 0.3% in Western Europe and North America, to more than 1% in parts of sub-Saharan Africa. The leading cause of blindness in most countries is cataract—approximately half of all blindness is caused by cataract. At present it is thought that there are seven million blind people in Africa, of whom 3.5 million are blind from cataract. Precise figures for the incidence of cataract blindness in Africa are not available, but it is estimated that at least 600 000 Africans become blind from cataract each year. By 2030, it is estimated that the population of Africa will have grown to 1380 million. If current trends in the prevalence of blindness in Africa are maintained, the number of cataract blind people will double. However, the population is not merely growing, it is also aging. By 2030 the number of people aged 60 or above, will have increased by 150%. As this age group is at greatest risk of cataract, it is likely that there will be a corresponding increase in the incidence of cataract blindness. Despite the enormous need, relatively few cataract operations are performed in Africa. In the industrialised countries, the cataract surgery rate is about 2500–3500 cataract operations per million population per year, whereas in most African countries it is 100–500. Most ophthalmologists in Africa carry out less than 300 operations per year. Why are so few operations performed when so many people need surgery? There are a large number of barriers that limit the access of blind people to cataract surgery. These can be divided into patient related and provider related factors. Broadly speaking, provider related factors can be overcome by improving the eYciency with which human and material resources are used, and by increasing these resources. Barriers related to patients’ isolation, ignorance, and impoverishment are much more diYcult to overcome. Probably the most important barrier to cataract surgery is poor motivation. Many cataract blind patients in Africa are not aware that their condition may be cured by surgery. Some people may be frightened by the thought of going to hospital. Others may simply be unimpressed by the results of cataract extraction. Most cataract surgery in Africa has taken the form of simple intracapsular cataract extraction followed by the provision of aphakic glasses. There is increasing evidence to suggest that this approach is of limited value. A population based study in northern Transvaal found that 9% of all blindness was due to uncorrected aphakia. Out of 33 patients who had cataract surgery, 13 (39%) had no glasses and were functionally blind. Another study in KwaZulu compared the prevalence of blindness in a district before and after a series of free eye camps, during which 113 cataract operations were carried out. 6 This showed that the number of people blind from cataract was reduced, but the number blind from uncorrected aphakia increased by almost the same amount, despite the provision of free aphakic spectacles. If bilateral cataract and uncorrected aphakia are both regarded as “cataract related” blindness, then performing 113 cataract extractions resulted in a total decline in “cataract related” blindness of only 16 people (Table 1). A similar pattern has been observed in Nepal, where long term follow up of 235 aphakic patients revealed that 30% of them had no glasses at all, and only 23% were wearing glasses in good condition. Aphakic glasses, in addition to causing the well known problems of magnification and distortion, are also heavy, uncomfortable, and fragile. When they are lost or broken, patients rarely feel that it is worth the cost and inconvenience of returning to the eye clinic to obtain another pair. Even when patients have their glasses, and a satisfactory visual acuity, they may well believe that their quality of life is significantly impaired by the necessity of wearing spectacles, and by the adverse optical eVects of aphakic correction. A second barrier to cataract surgery is poverty. In Africa, people who gradually become blind from bilateral cataract are usually destitute. What little savings they had will have been spent on food and other essentials. There will be no money to spare for surgery whose outcome is uncertain, and possibly unsatisfactory. At the same time, the macroeconomic policies pursued by many Africa countries, under the direction of the World Bank and the International Monetary Fund, dictate that patients must bear an increasing proportion of the costs of medical care. Many cataract blind patients are simply unable to aVord surgery. Thirdly, physical isolation hinders access to eye care. On average, there is only one ophthalmologist per million population in Africa. 2 Given the low population density in much of the continent, this means that many blind people will live more than 100 km from the nearest eye clinic. Roads are poor or non-existent, and public transport inconvenient, infrequent, and unsafe. For a blind person to travel in the face of such diYculties requires great commitment, and the assistance of at least one other family member. Provider related barriers include a shortage of trained eye care personnel; lack of essential drugs, materials, and equipment; and poor management of existing resources. These barriers can be overcome by training more eye workers, both physicians, and non-physicians; by making use of inexpensive locally produced materials and equipment; and by improving management. How will these barriers be aVected by the introduction of intraocular lenses as the routine treatment for aphakia? Firstly, the use of lens implants is likely to lead to an improved outcome. In South Africa, 98% of patients had a best corrected postoperative acuity of 6/24 or better, Table 1 Results of community based survey of blindness in KwaZulu 6