Prevalence of Age-Related Macular Degeneration in Nakuru, Kenya: A Cross-Sectional Population-Based Study
Kenya: A Cross-Sectional
Population-Based Study. PLoS Med 10(2): e1001393. doi:10.1371/journal.pmed.1001393
Prevalence of Age-Related Macular Degeneration in Nakuru, Kenya: A Cross-Sectional Population-Based Study
Wanjiku Mathenge 0
Andrew Bastawrous 0
Tunde Peto 0
Irene Leung 0
Allen Foster 0
Hannah Kuper 0
Susan Lewallen, Kilimanjaro Centre for Community Ophthalmology, Tanzania, United Republic of
0 1 International Centre for Eye Health, Department of Clinical Research, London School of Hygiene & Tropical Medicine , London , United Kingdom , 2 Department of Ophthalmology, Kigali Health Institute , Kigali, Rwanda, 3 The Fred Hollows Foundation-Eastern Africa, Nairobi , Kenya , 4 National Institute for Health Research Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology , London , United Kingdom
Background: Diseases of the posterior segment of the eye, including age-related macular degeneration (AMD), have recently been recognised as the leading or second leading cause of blindness in several African countries. However, prevalence of AMD alone has not been assessed. We hypothesized that AMD is an important cause of visual impairment among elderly people in Nakuru, Kenya, and therefore sought to assess the prevalence and predictors of AMD in a diverse adult Kenyan population. Methods and Findings: In a population-based cross-sectional survey in the Nakuru District of Kenya, 100 clusters of 50 people 50 y of age or older were selected by probability-proportional-to-size sampling between 26 January 2007 and 11 November 2008. Households within clusters were selected through compact segment sampling. All participants underwent a standardised interview and comprehensive eye examination, including dilated slit lamp examination by an ophthalmologist and digital retinal photography. Images were graded for the presence and severity of AMD lesions following a modified version of the International Classification and Grading System for Age-Related Maculopathy. Comparison was made between slit lamp biomicroscopy (SLB) and photographic grading. Of 4,381 participants, fundus photographs were gradable for 3,304 persons (75.4%), and SLB was completed for 4,312 (98%). Early and late AMD prevalence were 11.2% and 1.2%, respectively, among participants graded on images. Prevalence of AMD by SLB was 6.7% and 0.7% for early and late AMD, respectively. SLB underdiagnosed AMD relative to photographic grading by a factor of 1.7. After controlling for age, women had a higher prevalence of early AMD than men (odds ratio 1.5; 95% CI, 1.2-1.9). Overall prevalence rose significantly with each decade of age. We estimate that, in Kenya, 283,900 to 362,800 people 50 y and older have early AMD and 25,200 to 50,500 have late AMD, based on population estimates in 2007. Conclusions: AMD is an important cause of visual impairment and blindness in Kenya. Greater availability of low vision services and ophthalmologist training in diagnosis and treatment of AMD would be appropriate next steps. Please see later in the article for the Editors' Summary.
-
Competing Interests: The authors have declared that no competing interests exist.
Abbreviations: AMD, age-related macular degeneration; SES, socioeconomic status; SLB, slit lamp biomicroscopy.
In the latest estimates of global blindness and visual impairment
undertaken by the World Health Organization, in 2010,
agerelated macular degeneration (AMD) is the third most common
cause of blindness worldwide behind cataracts and glaucoma [1].
It has remained an important cause of blindness globally since the
last World Health Organization survey in 2002, in which it was
identified as the leading cause of blindness in high-income
countries [2]. As the global population ages, AMD is likely to
increase in importance. Currently, no curative treatment exists.
The recent promise of antivascular endothelial growth factor
treatments is unlikely to offset the growth of AMD globally, as
these treatments are only useful in exudative AMD and are not
currently widely accessible outside of high-income countries.
Nutritional interventions can reduce the progression of certain
subtypes of early AMD [3]; however, protective levels of required
vitamins and minerals are difficult to obtain in a healthy diet, and
the cost of supplementation is prohibitive for many who could
potentially benefit [4].
The majority of data on AMD available globally is from
population-based studies undertaken in white and Asian
populations [513], and few data are from peoples of African descent.
The data that do exist for individuals of African descent are largely
from studies undertaken in populations living outside of the
African continent [14,15]. It is presumed that AMD is rare in
Africans; however, in the last 10 y, African population-based
studies have suggested that posterior segment eye diseases are
highly prevalent, and this group of disorders, which includes
AMD, diabeti (...truncated)