An eye for detail: pin-pointing the causes of sight loss in rural Uganda

Loss of sight for many Africans is a personal tragedy which can be avoided.  In Uganda more than 30 000 people become blind or suffer visual impairment in both eyes every year. Identifying the causes of sight loss and where it is most prevalent within a country provide vital information to inform the development of eye health services. Eye health surveys can be conducted relatively cheaply by staff with limited training and supervision.

A worldwide programme “Vision 2020” was launched by the World Health Organisation with the target to reduce the number of blind people in the world from 75 to 25 million by the year 2020.  The programme requires not only commitment from governments to provide eye clinics and staff, but also accurate information about eye disease to determine the medical needs of the population.

The UK Medical Research Council, together with the International Centre for Eye Health, London, carried out a study into the incidence of sight loss in southwest Uganda.  Such a study has not been undertaken in the past because of the high costs involved. Data on the causes and incidence of sight loss may help to improve the targeting of eye health services in rural Uganda.

Masaka is a rural region of rolling hills and swamps with two rainy seasons each year.  The villagers make a living by subsistence agriculture growing coffee and bananas. 2124 people, living in 15 neighbouring villages in Masaka district, were given eye tests on two separate occasions, the first in 1994-5 and the second in 1997-8.  The villagers were given simple vision eye tests using laminated charts by staff without medical training to keep costs low.  Those with poor vision attended an eye clinic and were checked by an ophthalmologist for more detailed diagnosis and treatment.

The main causes of sight loss were:

• cataract
• refractive error
• macular degeneration
• chorioretinitis
• glaucoma
• corneal opacity. 

In young people, aged 13 to 34, loss of sight occurred in one person per year out of every 1000.  For the elderly, aged 65 and over, that figure had increased to 64 people per thousand losing their sight each year. The most frequent causes of loss of sight were cataract, which accounted for 41% of cases, followed by refractive error, which accounted for 13% of cases. Approximately 5% failed the sight test in one or in both eyes.

Of the 1997 people with normal vision at their first eye test:

• 56 developed visual impairment in the intervening three years
• 22 suffered from loss of sight in one eye
• 12 became completely blind in one eye
• 21 lost vision in both eyes
• one person became completely blind.

The study estimated that for the whole of Uganda, 30 348 people would become blind or partially sighted in both eyes each year.  However, this may be a low estimate, because the local people did not suffer from eye diseases which are common in other parts of Uganda, such as trachoma and vitamin A deficiency.  The number of people losing their sight each year will be an unmanageable burden on already overstretched eye services. 

Although the loss of eyesight is high in rural southwest Uganda, the main causes, such as cataract and refractive error, are very often treatable.  The findings of the study are essential for forecasting future trends and planning eye services in Africa. It is possible to conduct eye surveys cheaply using staff without medical training, supported by a small number of eye specialists.

Source(s):
‘Incidence of visual loss in rural southwest Uganda’, British Journal of Ophthalmology, 87: 829-833, by S.M. Mbulaiteye and B.C. Reeves, 2003
'Evaluation of E-optotypes as a screening test and the prevalence and causes of visual loss in a rural population in southwest Uganda', Ophthalmic Epidemiology 9(4): 251-262, by S.M. Mbulaiteye et al, 2002
'Causes and prevalence of non-vision impairing ocular conditions among a rural adult population in southwest Uganda', Ophthalmic Epidemiology 6(1): 41-48, by A. Kamali et al, 1999

Funded by: UK Medical Research Council; UK Department for International Development; Sightsavers UK

id21 Research Highlight: 10 June 2004

Further Information:
Sam M. Mbulaiteye
6120 Executive Boulevard
EPS 8007
MSC 7248
Rockville
MD 20852
USA

Contact the contributor: mbulaits@mail.nih.gov

Medical Research Council, UK

International Centre for Eye Health, London, UK

London School of Hygiene and Tropical Medicine, UK

Other related links:
'Keeping an eye on patient satisfaction - attendance at eye clinics in Uganda'

'Blinded by fear - why people with cataracts avoid eye surgery'

'Looking out for eye problems in Tanzanian children'

'Seeing sense: trial of a new treatment for trachoma in the Gambia'

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