Purchase this article with an account.
Nathan Congdon, Sheila K. West, Ralf R. Buhrmann, Anthony Kouzis, Beatriz Muñoz, Harran Mkocha; Prevalence of the Different Types of Age-Related Cataract in an African Population. Invest. Ophthalmol. Vis. Sci. 2001;42(11):2478-2482.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
purpose. To describe the prevalence of different types of cataract and their
association with visual acuity in a Tanzanian population aged 40 years
methods. A prevalence survey for lens opacity, glaucoma, and visual impairment
was carried out on all residents age 40 and older of six villages in
Kongwa, Tanzania. One examiner graded the lens for presence of nuclear
(NSC), posterior subcapsular (PSC), and cortical cataract (CC), using
the new WHO Simplified Cataract Grading System. Visual acuity was
measured in each eye, both presenting and best corrected, using an
illiterate E chart.
results. The proportion of eligible subjects participating was 90% (3268/3641).
The prevalence of cataract was as follows: NSC, 15.6%; CC, 8.8%; and
PSC, 1.9%. All types of cataract increased with age, from NSC, 1.7%;
CC, 2.4%; and PSC, 0.4% for those aged 40 to 49 years to NSC, 59.2%;
CC, 23.5%; and PSC, 5.9% for those aged 70 years and older
(P < 0.0001 for all cataract types,χ 2 test for trend). Cataract prevalence was higher among
women than men for NSC (P = 0.0001), but not for CC
(P = 0.15) or PSC (P = 0.25),
after adjusting for age. Prevalence rates of visual impairment
(BCVA < 6/12), US blindness (≤6/60) and WHO blindness (<6/120)
for this population were 13.3%, 2.1%, and 1.3%, respectively. Older
age and each of the major types of pure and mixed cataract were
independently associated with worse vision in regression modeling.
conclusions. Unlike African-derived populations in Salisbury and Barbados, NSC
rather than CC was most prevalent in this African population. The
seeming lower prevalence of CC may to some extent be explained by
different grading schemes, differential availability of cataract
surgery, the younger mean age of the Tanzanian subjects, and a higher
prevalence of NSC in this population.
This PDF is available to Subscribers Only