17
Epidemiology of AMD
Author, Study
Years study conducted, Country
Number of subjects, age
Prevalence of late AMD (%)
Barbados
Schachat, Barbados Eye Study
(7)
1987-1992, Barbados
N=3444, age 40-84 years
0.57
Japan
Oshima, Hisayama Study
(8)
1998, Japan
N=889, age >= 50 years
0.89
Kawasaki, Funagata Study
(9)
200-2002, Japan
N=1625, age >= 35 years
N=1037, age >= 55 years
0.5
0.8
India
Krishnaiah, Andrah Pradesh Study
(38)
1996-2000, India
N=3723, age >= 40 years
1.9
Nirmalan, Aravind Eye Study
(18)
1995-1997, India
N=4197, age >= 40 years
0.6
Krishnan, INDEYE
(19)
2005-2007, India
N=4266, age >= 60 years
1.2
China
Li, Beijing Eye Study
(11)
2001, China
N=4376, age >= 40 years
0.2
Taïwan
Chen, Shihpay Study
(12)
1999-2000, Taïwan
N=1105, age >= 65 years
1.9
Singapore
Kawasaki, Singapore Malay Eye Study
(13)
2004-2006, Singapore
N=3265, age 40-80 years
0.7
Greenland
Andersen, Greenland Inuit Eye Study
(14)
2002-2003, Greenland
N=642, age >= 60 years
9.1
Table 3. Prevalence of late AMD in other countries
4. Prevalence of early AMD
Late AMD is preceded by early, usually asymptomatic,
retinal abnormalities. The long-term cohort studies have
helped to characterize the lesions that are the most pre-
dictive of incident late AMD. While large soft drusen
(>125 microns) and pigmentary abnormalities clearly
are the hallmarks of early AMD, there is no consensus
on the precise definition of early AMD, and several clas-
sification systems coexist. This makes it difficult to assess
and compare the prevalence of early AMD among geo-
graphical areas and ethnic groups.
Despite these difficulties, it appears that early AMD is
frequent in the elderly. For instance, in the meta-analysis
by Friedman et al, the prevalence of large drusen increased
from about 1.5% in Caucasians aged 40-49 years, to
more than 25% in those aged 80 years or more
(3)
. Similar
rates were observed in the EUREYE Study, performed
in Europe
(4)
.
Consistently with what was observed for late AMD, early
AMD appears less frequent in African-Americans than
in Caucasian
(3,10)
. By contrast, while late AMD is also
less frequent in Hispanic-Americans, the prevalence of
early abnormalities appears similar, or even higher than
in Caucasians
(10,15-17)
. The reasons for these differences are
unclear, and suggest that different factors may be impli-
cated in the etiology of early and late AMD.
