Objective: To provide 4-year cumulative incidence and progression rates of
age-related lens opacities in a population greater than or equal to 40 year
s of age, which is mainly of African origin.
Design: Cohort study that reexamined surviving members of the population-ba
sed Barbados Eye Study 4 years after baseline.
Participants: Three thousand four hundred twenty-seven members of the Barba
dos Eye Study cohort (85% of those eligible).
Main Outcome Measures: The Lens Opacities Classification System II (LOCS II
) was used at the slit lamp. Cumulative incidence was defined as the develo
pment of any nuclear, cortical or posterior subcapsular (PSC) opacities (LO
CS II scores greater than or equal to 2) among persons without that opacity
type at baseline. Cumulative progression was defined by at least two-step
increases in scores among persons with preexisting lens opacities. Results:
The incidence of cortical opacities was about five times greater in black
than white participants (age-gender adjusted relative risk = 4.7; 95% confi
dence interval: 1.9-11.4). In the black population, the 4-year incidence ra
tes were 22.2% (20.4%-24.0%) for any cortical, 9.2% (8.2%-10.4%) for any nu
clear, and 3.3% (2.7%-4.0%) for any PSC opacities; rates increased greatly
with age. Four-year progression rates were 12.5% for cortical, 3.6% for nuc
lear, and 23.0% for PSC opacities, without consistent pattern by age. Women
had a greater risk of cortical and nuclear opacities (P < 0.05) than men a
nd greater progression of nuclear opacities. The presence of PSC opacities
at baseline seemed to at least double the incidence and progression rates o
f other opacities. In persons initially opacity free, single cortical opaci
ties were the predominant type to develop at followup. Visual acuity loss f
requently accompanied incident opacities,
Conclusions: This longitudinal study provides new population-based data on
the natural history of lens opacities. Incidence and progression of opaciti
es, especially of cortical opacities, were high. After 4 years of followup,
1 in 4 to 5 participants developed cortical opacities, 1 in 11 developed n
uclear opacities, and 1 in 30 developed PSC opacities. The information obta
ined attests to the public health impact of age-related cataract, as well a
s its extent, in this and similar black populations, (C) 2000 by the Americ
an Academy of Ophthalmology.