BioMed Central
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G$=-,6kZO BMC Ophthalmology
7
.+al)hl Research article Open Access
Ps>&"k$T Comparison of age-specific cataract prevalence in two
L.)yXuo4 population-based surveys 6 years apart
km 5E)_] Ava Grace Tan†, Jie Jin Wang*†, Elena Rochtchina† and Paul Mitchell†
.Q\\dESn" Address: Centre for Vision Research, Westmead Millennium Institute, Department of Ophthalmology, University of Sydney, Westmead Hospital,
8wFn}lw& Westmead, NSW, Australia
w|Qd` Email: Ava Grace Tan -
ava_tan@wmi.usyd.edu.au; Jie Jin Wang* -
jiejin_wang@wmi.usyd.edu.au;
==9ZFdf Elena Rochtchina -
elena_rochtchina@wmi.usyd.edu.au; Paul Mitchell -
paul_mitchell@wmi.usyd.edu.au pXW`+<g0 * Corresponding author †Equal contributors
;Bs^iL Abstract
i21QJ6jPcI Background: In this study, we aimed to compare age-specific cortical, nuclear and posterior
Yj8& subcapsular (PSC) cataract prevalence in two surveys 6 years apart.
=cp;Q,t'9L Methods: The Blue Mountains Eye Study examined 3654 participants (82.4% of those eligible) in
!J^tg2M8: cross-section I (1992–4) and 3509 participants (75.1% of survivors and 85.2% of newly eligible) in
z8iENECwj cross-section II (1997–2000, 66.5% overlap with cross-section I). Cataract was assessed from lens
8/q*o>[? photographs following the Wisconsin Cataract Grading System. Cortical cataract was defined if
*m&&1W_ cortical opacity comprised ≥ 5% of lens area. Nuclear cataract was defined if nuclear opacity ≥
0wvU?z%WK Wisconsin standard 4. PSC was defined if any present. Any cataract was defined to include persons
e_.~n<= who had previous cataract surgery. Weighted kappa for inter-grader reliability was 0.82, 0.55 and
:ICr\FY$ 0.82 for cortical, nuclear and PSC cataract, respectively. We assessed age-specific prevalence using
@ ;J|xkJ an interval of 5 years, so that participants within each age group were independent between the
k?-S`o%Q two surveys.
gKQ@!UU8 Results: Age and gender distributions were similar between the two populations. The age-specific
3-
)kwy6L prevalence of cortical (23.8% in 1st, 23.7% in 2nd) and PSC cataract (6.3%, 6.0%) was similar. The
{ _X#fq0} prevalence of nuclear cataract increased slightly from 18.7% to 23.9%. After age standardization,
"1%*'B^}bw the similar prevalence of cortical (23.8%, 23.5%) and PSC cataract (6.3%, 5.9%), and the increased
rCrr
"O#j prevalence of nuclear cataract (18.7%, 24.2%) remained.
a71}y;W Conclusion: In two surveys of two population-based samples with similar age and gender
Q9q9<J7j$ distributions, we found a relatively stable cortical and PSC cataract prevalence over a 6-year period.
k4mTZ}6E The increased prevalence of nuclear cataract deserves further study.
/MxCvEE Background
Dauo(Uhuo Age-related cataract is the leading cause of reversible visual
05g?jV impairment in older persons [1-6]. In Australia, it is
9/H^t*5t estimated that by the year 2021, the number of people
P.1Qc)m4 affected by cataract will increase by 63%, due to population
a;yV#Y aging [7]. Surgical intervention is an effective treatment
L]NYYP- for cataract and normal vision (> 20/40) can usually
0k7"H]J be restored with intraocular lens (IOL) implantation.
{5.?'vMp Cataract surgery with IOL implantation is currently the
i59k"pNm most commonly performed, and is, arguably, the most
T/Ez*iQW cost effective surgical procedure worldwide. Performance
2}@*Ki7 Published: 20 April 2006
-%N}A3m!5 BMC Ophthalmology 2006, 6:17 doi:10.1186/1471-2415-6-17
MIJ%_=sm4: Received: 14 December 2005
5I_hh?N4Z Accepted: 20 April 2006
%rX\
P This article is available from:
http://www.biomedcentral.com/1471-2415/6/17 Q.uR<C6)v © 2006 Tan et al; licensee BioMed Central Ltd.
/$<JCNGv This is an Open Access article distributed under the terms of the Creative Commons Attribution License (
http://creativecommons.org/licenses/by/2.0),
'>4+WZ1w5 which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
bsD'\ BMC Ophthalmology 2006, 6:17
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c/3^e (page number not for citation purposes)
dUUPhk0 of this surgical procedure has been continuously increasing
.Wd.)^? in the last two decades. Data from the Australian
EgCp:L{ Health Insurance Commission has shown a steady
zww? increase in Medicare claims for cataract surgery [8]. A 2.6-
,2E`:#$ fold increase in the total number of cataract procedures
t>m8iS> from 1985 to 1994 has been documented in Australia [9].
~7KynE The rate of cataract surgery per thousand persons aged 65
\>w@=bq26 years or older has doubled in the last 20 years [8,9]. In the
zS,%msT^A Blue Mountains Eye Study population, we observed a onethird
]i9H_K increase in cataract surgery prevalence over a mean
}D8~^ 6-year interval, from 6% to nearly 8% in two cross-sectional
Ma
n^\gkCi population-based samples with a similar age range
$#g#[/ [10]. Further increases in cataract surgery performance
".Tf<F would be expected as a result of improved surgical skills
N8u_=b{X and technique, together with extending cataract surgical
l;
"ub^AH benefits to a greater number of older people and an
uKaf{=* increased number of persons with surgery performed on
=k[(rvU3 both eyes.
n-L]YrDPK[ Both the prevalence and incidence of age-related cataract
Qu,)wfp~ link directly to the demand for, and the outcome of, cataract
ft*G*.0kO surgery and eye health care provision. This report
sPZV>Q:zY aimed to assess temporal changes in the prevalence of cortical
h7Shl<f and nuclear cataract and posterior subcapsular cataract
NzwGc+\7} (PSC) in two cross-sectional population-based
?eYchVq surveys 6 years apart.
+c~O0U1 Methods
{VrAh*
#h
The Blue Mountains Eye Study (BMES) is a populationbased
=1uj1.h cohort study of common eye diseases and other
[57V8% health outcomes. The study involved eligible permanent
)%nt61P\W residents aged 49 years and older, living in two postcode
reD[j,i&t. areas in the Blue Mountains, west of Sydney, Australia.
3XYIbXnk Participants were identified through a census and were
mt&JgA/ invited to participate. The study was approved at each
$bM#\2' stage of the data collection by the Human Ethics Committees
eO"\UDBV of the University of Sydney and the Western Sydney
ZJ{+_ax0K Area Health Service and adhered to the recommendations
UJyiRP:#]> of the Declaration of Helsinki. Written informed consent
"O"^\f was obtained from each participant.
}I'>r(K Details of the methods used in this study have been
S^sW.(I described previously [11]. The baseline examinations
joSr,'x (BMES cross-section I) were conducted during 1992–
gIf+.^/m1 1994 and included 3654 (82.4%) of 4433 eligible residents.
wft:eQ Follow-up examinations (BMES IIA) were conducted
lk *QV during 1997–1999, with 2335 (75.0% of BMES
30T:* I| cross section I survivors) participating. A repeat census of
D9pxe qf+= the same area was performed in 1999 and identified 1378
@bVh?T0~F, newly eligible residents who moved into the area or the
CI3_lWax% eligible age group. During 1999–2000, 1174 (85.2%) of
5qAE9G!c this group participated in an extension study (BMES IIB).
crOtQ BMES cross-section II thus includes BMES IIA (66.5%)
]nr
BmKB and BMES IIB (33.5%) participants (n = 3509).
Am}PXj6 Similar procedures were used for all stages of data collection
2ShlYW@~ at both surveys. A questionnaire was administered
<45dy5!Tz including demographic, family and medical history. A
C&#KdvN/r detailed eye examination included subjective refraction,
W$ d{ slit-lamp (Topcon SL-7e camera, Topcon Optical Co,
;@;ie8H Tokyo, Japan) and retroillumination (Neitz CT-R camera,
07WIa@Q Neitz Instrument Co, Tokyo, Japan) photography of the
~.y4
,- lens. Grading of lens photographs in the BMES has been
JqV<A3i previously described [12]. Briefly, masked grading was
yl;$#aZB performed on the lens photographs using the Wisconsin
sOtNd({ Cataract Grading System [13]. Cortical cataract and PSC
A.cZa were assessed from the retroillumination photographs by
p]IhQnj2 estimating the percentage of the circular grid involved.
^Y*.Ktp,o Cortical cataract was defined when cortical opacity
b}{9
:n/SC involved at least 5% of the total lens area. PSC was defined
u$`x]K=Zsm when opacity comprised at least 1% of the total lens area.
j*lWi0Z- Slit-lamp photographs were used to assess nuclear cataract
dCJR,},\f using the Wisconsin standard set of four lens photographs
C(Gb [13]. Nuclear cataract was defined when nuclear opacity
yA)
+- was at least as great as the standard 4 photograph. Any cataract
j`-y"6) was defined to include persons who had previous
IXk'?9 cataract surgery as well as those with any of three cataract
)RKhEm%Vr2 types. Inter-grader reliability was high, with weighted
HC, 0"W kappa 0.82 for cortical cataract, 0.55 (simple kappa 0.75)
`U>b6{K for nuclear cataract and 0.82 for PSC grading. The intragrader
-bX.4+U reliability for nuclear cataract was assessed with
oUS>p": simple kappa 0.83 for the senior grader who graded
K`83C`w. nuclear cataract at both surveys. All PSC cases were confirmed
&ZFAUE
,[ by an ophthalmologist (PM).
;,hoX6D$ In cross-section I, 219 persons (6.0%) had missing or
(ZR"O8 ungradable Neitz photographs, leaving 3435 with photographs
}^bL' available for cortical cataract and PSC assessment,
L6}x3 while 1153 (31.6%) had randomly missing or ungradable
5'[X&r%# Topcon photographs due to a camera malfunction, leaving
&l*dYzqq 2501 with photographs available for nuclear cataract
<^Nj~+G' assessment. Comparison of characteristics between participants
I%WK*AORM with and without Neitz or Topcon photographs in
-L<Pm(v& cross-section I showed no statistically significant differences
Xr;noV-X between the two groups, as reported previously
UR=s{nFd [12]. In cross-section II, 441 persons (12.5%) had missing
dNt|"9~& or ungradable Neitz photographs, leaving 3068 for cortical
K:Go%3~, cataract and PSC assessment, and 648 (18.5%) had
0PbIWy' missing or ungradable Topcon photographs, leaving 2860
=KD*+.'\/ for nuclear cataract assessment.
zUu>kJZ Data analysis was performed using the Statistical Analysis
~n
9DG>a System (SAS, SAS Institute, Cary, NC, USA). Age-adjusted
',%&DA2 prevalence was calculated using direct standardization of
\Y 4Z Q"0Q the cross-section II population to the cross-section I population.
ZEJadR We assessed age-specific prevalence using an
n(1"6 interval of 5 years, so that participants within each age
&3?yg61Ag group were independent between the two cross-sectional
B.WkHY%/ surveys.
jYZWf `X~ BMC Ophthalmology 2006, 6:17
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O{R5<"g (page number not for citation purposes)
F'*&-l Results
Ee&$9 )t Characteristics of the two survey populations have been
%%[TM(z previously compared [14] and showed that age and sex
g7F
Z - distributions were similar. Table 1 compares participant
ijYLf.R< characteristics between the two cross-sections. Cross-section
^)pY2t<^ II participants generally had higher rates of diabetes,
s30_lddD hypertension, myopia and more users of inhaled steroids.
Q(3x"+ Cataract prevalence rates in cross-sections I and II are
.D`#a shown in Figure 1. The overall prevalence of cortical cataract
^IYN"yX_ was 23.8% and 23.7% in cross-sections I and II,
?Sxnq#r# respectively (age-sex adjusted P = 0.81). Corresponding
[\yI<^_a prevalence of PSC was 6.3% and 6.0% for the two crosssections
e8.bH# (age-sex adjusted P = 0.60). There was an
8msDJ{,X increased prevalence of nuclear cataract, from 18.7% in
uBgHtjmae cross-section I to 23.9% in cross-section II over the 6-year
0%/(p?]M period (age-sex adjusted P < 0.001). Prevalence of any cataract
STI3|}G*P (including persons who had cataract surgery), however,
3!L)7Z/ was relatively stable (46.9% and 46.8% in crosssections
1<"kN^ I and II, respectively).
;4IP7$3G After age-standardization, these prevalence rates remained
CHB{P\WF stable for cortical cataract (23.8% and 23.5% in the two
th)jEK;Z surveys) and PSC (6.3% and 5.9%). The slightly increased
;}qCIyuO] prevalence of nuclear cataract (from 18.7% to 24.2%) was
![V-
e not altered.
HApP*1J^c Table 2 shows the age-specific prevalence rates for cortical
Me>'QVr cataract, PSC and nuclear cataract in cross-sections I and
$;1~JOZh II. A similar trend of increasing cataract prevalence with
hl+Yr)0\ increasing age was evident for all three types of cataract in
g:g>;"B
O both surveys. Comparing the age-specific prevalence
49m/UeNZ between the two surveys, a reduction in PSC prevalence in
Ft}tIP7 cross-section II was observed in the older age groups (≥ 75
wkGF&U years). In contrast, increased nuclear cataract prevalence
Q8n?7JB in cross-section II was observed in the older age groups (≥
Fk43sqU6~ 70 years). Age-specific cortical cataract prevalence was relatively
U#
}.r< consistent between the two surveys, except for a
{IVqV6: reduction in prevalence observed in the 80–84 age group
)+G(4eIT and an increasing prevalence in the older age groups (≥ 85
Ub$$wOsf years).
`6A"eDa Similar gender differences in cataract prevalence were
dXj.e4,m observed in both surveys (Table 3). Higher prevalence of
}bVyv
H cortical and nuclear cataract in women than men was evident
SUw{xGp
but the difference was only significant for cortical
TwN8|ibVmP cataract (age-adjusted odds ratio, OR, for women 1.3,
SXL6)pX 95% confidence intervals, CI, 1.1–1.5 in cross-section I
+CkK4<dF and OR 1.4, 95% CI 1.1–1.6 in cross-section II). In con-
?9mY #_Of Table 1: Participant characteristics.
-=RXhE_{ Characteristics Cross-section I Cross-section II
+ |,CIl+ n % n %
(Gc5lMiX3 Age (mean) (66.2) (66.7)
}Z6/b
_kV 50–54 485 13.3 350 10.0
L,<.rr$: 55–59 534 14.6 580 16.5
38#(ruv 60–64 638 17.5 600 17.1
N%-nxbI\ 65–69 671 18.4 639 18.2
+[F8>9o& 70–74 538 14.7 572 16.3
Q3DxjD 75–79 422 11.6 407 11.6
h^
s}8y 80–84 230 6.3 226 6.4
_i
8oWy1 85–89 100 2.7 110 3.1
Rz)#VVYC= 90+ 36 1.0 24 0.7
&ke4":7X Female 2072 56.7 1998 57.0
Ov9.qNT Ever Smokers 1784 51.2 1789 51.2
Ort\J~O Use of inhaled steroids 370 10.94 478 13.8^
xQ[YQ!l History of:
^j`
vk
Diabetes 284 7.8 347 9.9^
qg O)@B+ Hypertension 1669 46.0 1825 52.2^
-K0tK~%q Emmetropia* 1558 42.9 1478 42.2
wFvilF
V Myopia* 442 12.2 495 14.1^
SXT/9FteZ Hyperopia* 1633 45.0 1532 43.7
6Z"%vrH n = number of persons affected
bHP-Z9riv * best spherical equivalent refraction correction
LOA
90.D ^ P < 0.01
qgDBu\ BMC Ophthalmology 2006, 6:17
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7+ysE (page number not for citation purposes)
\yy!?Ul
aI t
NE! Xt<A rast, men had slightly higher PSC prevalence than women
@iaN@`5I6s in both cross-sections but the difference was not significant
}bHpFe (OR 1.1, 95% CI 0.8–1.4 for men in cross-section I
8(A:XQN"h and OR 1.2, 95% 0.9–1.6 in cross-section II).
R%Z} JR. Discussion
9\xw}ph Findings from two surveys of BMES cross-sectional populations
1eJ\CdI with similar age and gender distribution showed
/i"EVN`t that the prevalence of cortical cataract and PSC remained
Y7p#K<y]9 stable, while the prevalence of nuclear cataract appeared
wD<G+Y} to have increased. Comparison of age-specific prevalence,
4
8DsRy with totally independent samples within each age group,
4qMHVPJv\ confirmed the robustness of our findings from the two
Vs"Z9p$U survey samples. Although lens photographs taken from
v`fUAm/ the two surveys were graded for nuclear cataract by the
$?A]!Y; same graders, who documented a high inter- and intragrader
LgaJp_d>9* reliability, we cannot exclude the possibility that
qq/Cn4fN8 variations in photography, performed by different photographers,
&#;,
P:.' may have contributed to the observed difference
4[#.N
3Y4* in nuclear cataract prevalence. However, the overall
3aOFpCs|# Table 2: Age-specific prevalence of cataract types in cross sections I and II.
KIS.4nt#d" Cataract type Age (years) Cross-section I Cross-section II
zqeU>V~<F n % (95% CL)* n % (95% CL)*
P-mrH Cortical 50–54 473 4.4 (2.6–6.3) 338 7.4 (4.6–10.2)
4S=lO?\"A 55–59 522 9.2 (6.7–11.7) 542 9.0 (6.6–11.5)
kb6v2 ^8H 60–64 615 16.4 (13.5–19.4) 556 16.7 (13.6–19.8)
_
&M>f?l 65–69 653 26.2 (22.8–29.6) 581 23.6 (20.1–27.0)
CuGk?i 70–74 516 31.2 (27.2–35.2) 514 35.4 (31.3–39.6)
Grqs*V &|g 75–79 366 40.2 (35.1–45.2) 332 39.8 (34.5–45.1)
?R+$4;iy 80–84 194 58.8 (51.8–65.8) 163 42.9 (35.3–50.6)
`Ctj]t 85–89 74 52.7 (41.1–64.4) 73 54.8 (43.1–66.5)
M{H&5 9v 90+ 22 68.2 (47.0–89.3) 14 78.6 (54.0–103.2)
Mc8^{br61 PSC 50–54 474 2.7 (1.3–4.2) 338 2.4 (0.7–4.0)
`MD/CFl4 55–59 522 2.9 (1.4–4.3) 541 2.6 (1.3–3.9)
s6egd%r 60–64 616 4.6 (2.9–6.2) 548 5.7 (3.7–7.6)
[q@%)F 65–69 655 6.3 (4.4–8.1) 573 4.5 (2.8–6.3)
l g
C 70–74 517 6.8 (4.6–8.9) 505 9.7 (7.1–12.3)
|j+~Td3})& 75–79 367 11.4 (8.2–14.7) 327 9.5 (6.3–12.7)
M~6I-HexT| 80–84 196 12.2 (7.6–16.9) 155 10.3 (5.5–15.2)
usA!MMH4 85–89 74 18.9 (9.8–28.1) 69 11.6 (3.9–19.4)
pGFocw 90+ 23 21.7 (3.5–40.0) 11 0.0
h(L5MZs Nuclear 50–54 323 1.6 (0.2–2.9) 331 0.9 (–0.2–1.9)
7Av]f3
Zr 55–59 386 2.3 (0.8–3.8) 507 3.6 (1.9–5.2)
fwEi//1 60–64 453 5.3 (3.2–7.4) 501 11.6 (8.8–14.4)
?,NAihN] 65–69 478 17.2 (13.8–20.1) 534 18.5 (15.2–21.9)
j{=%~ 70–74 392 27.6 (23.1–32.0) 453 36.0 (31.6–40.4)
(}:xs,Ax 75–79 255 45.1 (39.0–51.3) 302 55.6 (50.0–61.3)
HL?pnT09 80–84 146 54.1 (45.9–62.3) 147 73.5 (66.3–80.7)
$d"+Njd 85–89 50 64.0 (50.2–77.8) 70 80.0 (70.4–89.6)
J3]m*i5A
90+ 18 72.2 (49.3–95.1) 15 73.3 (48.0–98.7)
!=we7vK} n = number of persons
OK 6}9Eu9 * 95% Confidence Limits
{ SfU! Cataract FMioguunrtea i1n ps rEeyvea lSetnucdey in cross-sections I and II of the Blue
!xI![N^ Cataract prevalence in cross-sections I and II of the Blue
d1-p];& Mountains Eye Study.
>MT)=4
9q 0
H
#BgE29 10
#!/Nmd=Nj 20
To`?<]8 30
wu')Q/v 40
5glGlD6R 50
i`qh|w/b_ cortical PSC nuclear any
>=H8>X cataract
GLyh1qNX Cataract type
ui1m+ %
ks D1NB;9 Cross-section I
c &HoS Cross-section II
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=&b[V" (page number not for citation purposes)
vEGK
{rMA prevalence of any cataract (including cataract surgery) was
Oe`t!&v relatively stable over the 6-year period.
z7
C1&bGe Although different population-based studies used different
U5"OhI grading systems to assess cataract [15], the overall
V
m.@qO*= prevalence of the three cataract types were similar across
W<"\hQI different study populations [12,16-23]. Most studies have
N/BU%c
ph+ suggested that nuclear cataract is the most prevalent type
WKsx|a]U of cataract, followed by cortical cataract [16-20]. Ours and
+ctv]'P_ other studies reported that cortical cataract was the most
sfE8b/Z8 prevalent type [12,21-23].
Oy$BR
<\ Our age-specific prevalence data show a reduction of
8
-A7 15.9% in cortical cataract prevalence for the 80–84 year
QE2^.|d{ age group, concordant with an increase in cataract surgery
0(x@
NGb>{ prevalence by 9% in those aged 80+ years observed in the
rrYp^xLa` same study population [10]. Although cortical cataract is
B}+9U thought to be the least likely cataract type leading to a cataract
~-wJ#E3g surgery, this may not be the case in all older persons.
%PbqASm A relatively stable cortical cataract and PSC prevalence
F*VMS over the 6-year period is expected. We cannot offer a
+z0}{,HX definitive explanation for the increase in nuclear cataract
yMl'1W prevalence. A possible explanation could be that a moderate
L]N2rMM level of nuclear cataract causes less visual disturbance
=@=R)C4f* than the other two types of cataract, thus for the oldest age
&\|<3sd( groups, persons with nuclear cataract could have been less
<Cu?$ likely to have surgery unless it is very dense or co-existing
myOX:K* with cortical cataract or PSC. Previous studies have shown
o~_>p/7; that functional vision and reading performance were high
E(kpK5h{ in patients undergoing cataract surgery who had nuclear
cjC6\.+l3 cataract only compared to those with mixed type of cataract
g*?+~0"`Y (nuclear and cortical) or PSC [24,25]. In addition, the
I S8nvx\ overall prevalence of any cataract (including cataract surgery)
^.kAZSgO was similar in the two cross-sections, which appears
9$V_=Bo to support our speculation that in the oldest age group,
0gD59N'C nuclear cataract may have been less likely to be operated
>ydb? than the other two types of cataract. This could have
RG
r'<o) resulted in an increased nuclear cataract prevalence (due
7h9[-d6 to less being operated), compensated by the decreased
e$+f~~K prevalence of cortical cataract and PSC (due to these being
6
Y_O^f more likely to be operated), leading to stable overall prevalence
|;u%JW$4 of any cataract.
yX.5Y|A< Possible selection bias arising from selective survival
(&S[R{=^j among persons without cataract could have led to underestimation
7M#$: Fdb of cataract prevalence in both surveys. We
@W\4UX3dK assume that such an underestimation occurred equally in
1;:t~Y both surveys, and thus should not have influenced our
`Ivw`}L assessment of temporal changes.
Prb_/B Dd Measurement error could also have partially contributed
#w,WwL! to the observed difference in nuclear cataract prevalence.
~? FrI Assessment of nuclear cataract from photographs is a
?+,*YVT potentially subjective process that can be influenced by
7hF,gl5 variations in photography (light exposure, focus and the
W^d4/] slit-lamp angle when the photograph was taken) and
Q_]!an( grading. Although we used the same Topcon slit-lamp
,;cel^.b camera and the same two graders who graded photos
F;Q_*0mIQ from both surveys, we are still not able to exclude the possibility
*0&4mi8 of a partial influence from photographic variation
eN|HJ= on this result.
{GQ
Aa A similar gender difference (women having a higher rate
#7~tL23}] than men) in cortical cataract prevalence was observed in
\at-"[. both surveys. Our findings are in keeping with observations
N(_
.N6 from the Beaver Dam Eye Study [18], the Barbados
]D?# \| Eye Study [22] and the Lens Opacities Case-Control
BbXU|QtY Group [26]. It has been suggested that the difference
~X~xE]1o|U could be related to hormonal factors [18,22]. A previous
xgtJl}
L study on biochemical factors and cataract showed that a
T\2) $ lower level of iron was associated with an increased risk of
qu<B%v cortical cataract [27]. No interaction between sex and biochemical
d DIQ+/mmg factors were detected and no gender difference
D%;wVnUw was assessed in this study [27]. The gender difference seen
A#Q0{z@H in cortical cataract could be related to relatively low iron
462!;/y levels and low hemoglobin concentration usually seen in
VBbUl|X\ women [28]. Diabetes is a known risk factor for cortical
W>}Qer4 Table 3: Gender distribution of cataract types in cross-sections I and II.
Th7wP:iDP Cataract type Gender Cross-section I Cross-section II
8S.')<-f n % (95% CL)* n % (95% CL)*
HUU >hq9 Cortical Male 1496 21.1 (19.0–23.1) 1328 20.4 (18.2–22.6)
P[rAJJN/E Female 1939 25.9 (23.9–27.8) 1785 26.2 (24.2–28.3)
q)K-vt)98 PSC Male 1500 6.5 (5.2–7.7) 1314 6.4 (5.1–7.7)
`d}W;&c Female 1944 6.2 (5.1–7.2) 1753 5.7 (4.6–6.7)
6P%<[Z Nuclear Male 1106 17.6 (15.4–19.9) 1225 22.5 (20.1–24.8)
'GV&] Female 1395 19.5 (17.4–21.6) 1635 25.0 (22.9–27.1)
\#\`!L[1 n = number of persons
|`_ <@b * 95% Confidence Limits
u;+%Qh BMC Ophthalmology 2006, 6:17
http://www.biomedcentral.com/1471-2415/6/17 6?%]odI# Page 6 of 7
F-$Z,Q]S (page number not for citation purposes)
lQh
E]m>+ cataract but in this particular population diabetes is more
Jj=yG"$! prevalent in men than women in all age groups [29]. Differential
2UU2Vm_6 exposures to cataract risk factors or different dietary
Hi]vHG( or lifestyle patterns between men and women may
=gW"#ZjL){ also be related to these observations and warrant further
"2ZIoa!^ study.
?JuX~{{.L Conclusion
x9xz
m5 In summary, in two population-based surveys 6 years
/\TQc-k?2 apart, we have documented a relatively stable prevalence
|f"-|6 of cortical cataract and PSC over the period. The observed
g/OI|1a overall increased nuclear cataract prevalence by 5% over a
f|X[gL,B 6-year period needs confirmation by future studies, and
AU0$A403 reasons for such an increase deserve further study.
Ezi' 2Sc Competing interests
@b]VCv0*f% The author(s) declare that they have no competing interests.
q|n97.vD Authors' contributions
'GrRuT< AGT graded the photographs, performed literature search
H!Wis3S3G and wrote the first draft of the manuscript. JJW graded the
p:Iw%eZ: photographs, critically reviewed and modified the manuscript.
:0B
|<~lX ER performed the statistical analysis and critically
1T!cc%ah reviewed the manuscript. PM designed and directed the
kVWGDI$~ study, adjudicated cataract cases and critically reviewed
nARxn#<+ and modified the manuscript. All authors read and
T48BRVX-F approved the final manuscript.
{V.Wk Acknowledgements
d
"2wO[ This study was supported by the Australian National Health & Medical
+:}kZDl@ X Research Council, Canberra, Australia (Grant Nos 974159, 991407). The
Dp^"J85}
abstract was presented at the Association for Research in Vision and Ophthalmology
{":c@I (ARVO) meeting in Fort Lauderdale, Florida, USA, May 2005.
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