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楼主  发表于: 2009-06-04   

BMC Ophthalmology

BioMed Central >0I\w$L  
Page 1 of 7  n w  
(page number not for citation purposes) !}L cJ  
BMC Ophthalmology N@R?<a  
Research article Open Access |.LE`  
Comparison of age-specific cataract prevalence in two z&Lcl{<MA  
population-based surveys 6 years apart #)( D_*  
Ava Grace Tan†, Jie Jin Wang*†, Elena Rochtchina† and Paul Mitchell† iTJE:[W"y  
Address: Centre for Vision Research, Westmead Millennium Institute, Department of Ophthalmology, University of Sydney, Westmead Hospital, _yc &'Wq  
Westmead, NSW, Australia A(wuRXnVWK  
Email: Ava Grace Tan - ava_tan@wmi.usyd.edu.au; Jie Jin Wang* - jiejin_wang@wmi.usyd.edu.au; DQ= /Jr~  
Elena Rochtchina - elena_rochtchina@wmi.usyd.edu.au; Paul Mitchell - paul_mitchell@wmi.usyd.edu.au u-HBmL  
* Corresponding author †Equal contributors w~WW2 w  
Abstract r*t\F& D  
Background: In this study, we aimed to compare age-specific cortical, nuclear and posterior '<&rMn  
subcapsular (PSC) cataract prevalence in two surveys 6 years apart. qp2&Z8S\D  
Methods: The Blue Mountains Eye Study examined 3654 participants (82.4% of those eligible) in O 718s\#  
cross-section I (1992–4) and 3509 participants (75.1% of survivors and 85.2% of newly eligible) in FuFA/R=x/  
cross-section II (1997–2000, 66.5% overlap with cross-section I). Cataract was assessed from lens 3/4r\%1b+  
photographs following the Wisconsin Cataract Grading System. Cortical cataract was defined if OLyl.#J  
cortical opacity comprised ≥ 5% of lens area. Nuclear cataract was defined if nuclear opacity ≥ Ogp@!  
Wisconsin standard 4. PSC was defined if any present. Any cataract was defined to include persons 1ika'  
who had previous cataract surgery. Weighted kappa for inter-grader reliability was 0.82, 0.55 and !Bn,f 2  
0.82 for cortical, nuclear and PSC cataract, respectively. We assessed age-specific prevalence using gt Rs||  
an interval of 5 years, so that participants within each age group were independent between the ]xN)>A2  
two surveys. U t.#h="  
Results: Age and gender distributions were similar between the two populations. The age-specific .@3bz  
prevalence of cortical (23.8% in 1st, 23.7% in 2nd) and PSC cataract (6.3%, 6.0%) was similar. The Oq*=oz^~1  
prevalence of nuclear cataract increased slightly from 18.7% to 23.9%. After age standardization, 3}2a3)  
the similar prevalence of cortical (23.8%, 23.5%) and PSC cataract (6.3%, 5.9%), and the increased ]% I|C++0  
prevalence of nuclear cataract (18.7%, 24.2%) remained. CL<m+dW%*  
Conclusion: In two surveys of two population-based samples with similar age and gender TV*@h2C"i  
distributions, we found a relatively stable cortical and PSC cataract prevalence over a 6-year period. 28 7)\FU;3  
The increased prevalence of nuclear cataract deserves further study. uui3jZ:  
Background )G@/E^ySM  
Age-related cataract is the leading cause of reversible visual |RZI]H%  
impairment in older persons [1-6]. In Australia, it is &,C;_3   
estimated that by the year 2021, the number of people FmC [u  
affected by cataract will increase by 63%, due to population T/ TMi&:?.  
aging [7]. Surgical intervention is an effective treatment ><"0GPxrx  
for cataract and normal vision (> 20/40) can usually {Q AV  
be restored with intraocular lens (IOL) implantation. esK0H<]  
Cataract surgery with IOL implantation is currently the +~eybm;  
most commonly performed, and is, arguably, the most *#Hw6N0#   
cost effective surgical procedure worldwide. Performance t BKra  
Published: 20 April 2006 (bON[6OGm  
BMC Ophthalmology 2006, 6:17 doi:10.1186/1471-2415-6-17 IHvrx:7   
Received: 14 December 2005 B),Z*lpC  
Accepted: 20 April 2006 0:q R,NW^#  
This article is available from: http://www.biomedcentral.com/1471-2415/6/17 @"'$e_jj"  
© 2006 Tan et al; licensee BioMed Central Ltd. 0=V - {  
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), <^fvTb&*  
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. c`xgz# ]v  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 X^9eCj;c  
Page 2 of 7 ^Bu55q  
(page number not for citation purposes) ,BE4z2a  
of this surgical procedure has been continuously increasing =Bw2{]w  
in the last two decades. Data from the Australian Ym$=^f]-  
Health Insurance Commission has shown a steady FgTWym_  
increase in Medicare claims for cataract surgery [8]. A 2.6- 5;q{9wvqO  
fold increase in the total number of cataract procedures g ~]?6;uu  
from 1985 to 1994 has been documented in Australia [9]. D%!GY1wdn  
The rate of cataract surgery per thousand persons aged 65 sG8G}f  
years or older has doubled in the last 20 years [8,9]. In the )Rr0f 8  
Blue Mountains Eye Study population, we observed a onethird >S'IrnH'!  
increase in cataract surgery prevalence over a mean sX,S]:X  
6-year interval, from 6% to nearly 8% in two cross-sectional MyaJhA6c  
population-based samples with a similar age range OS sYmF  
[10]. Further increases in cataract surgery performance xvTz|Y  
would be expected as a result of improved surgical skills }B@44HdY  
and technique, together with extending cataract surgical ,f^ ICM  
benefits to a greater number of older people and an R/Z zmb{  
increased number of persons with surgery performed on MkX=34oc^  
both eyes. |ZtNCB5{^j  
Both the prevalence and incidence of age-related cataract MZ"|Jn  
link directly to the demand for, and the outcome of, cataract tZan1C%p>  
surgery and eye health care provision. This report ][`%vj9r  
aimed to assess temporal changes in the prevalence of cortical {.o@XP,.  
and nuclear cataract and posterior subcapsular cataract }va>jfy  
(PSC) in two cross-sectional population-based  4}F~h  
surveys 6 years apart. ppzQh1  
Methods cUC!'+L  
The Blue Mountains Eye Study (BMES) is a populationbased /_</m?&.U&  
cohort study of common eye diseases and other tR(nD UHV5  
health outcomes. The study involved eligible permanent r$W%d[pB  
residents aged 49 years and older, living in two postcode %jn)=;\  
areas in the Blue Mountains, west of Sydney, Australia. v"-K-AQjB  
Participants were identified through a census and were 0t7vg#v|  
invited to participate. The study was approved at each \IZY\WU}2  
stage of the data collection by the Human Ethics Committees vKBi jmE  
of the University of Sydney and the Western Sydney n50W HlMtt  
Area Health Service and adhered to the recommendations SM\qd4  
of the Declaration of Helsinki. Written informed consent ZQ{-6VCjl  
was obtained from each participant. nXw98;  
Details of the methods used in this study have been '^M.;Giz  
described previously [11]. The baseline examinations |=AaGJx  
(BMES cross-section I) were conducted during 1992– `IT]ZAem`/  
1994 and included 3654 (82.4%) of 4433 eligible residents. GglGFXOL-  
Follow-up examinations (BMES IIA) were conducted nx{MUN7  
during 1997–1999, with 2335 (75.0% of BMES }:57Ym)7w  
cross section I survivors) participating. A repeat census of B>g(i=E  
the same area was performed in 1999 and identified 1378 EB VG@  
newly eligible residents who moved into the area or the ?AK`M #M  
eligible age group. During 1999–2000, 1174 (85.2%) of 9}5o> iR  
this group participated in an extension study (BMES IIB). glLoYRTi  
BMES cross-section II thus includes BMES IIA (66.5%) 9g]%}+D  
and BMES IIB (33.5%) participants (n = 3509). 6V*,nocL_+  
Similar procedures were used for all stages of data collection -iL:D<!Cb_  
at both surveys. A questionnaire was administered me@)kQ8M  
including demographic, family and medical history. A SDB \6[D  
detailed eye examination included subjective refraction, 4:5M,p  
slit-lamp (Topcon SL-7e camera, Topcon Optical Co, G.`},c;A-  
Tokyo, Japan) and retroillumination (Neitz CT-R camera, UE/JV_/S;  
Neitz Instrument Co, Tokyo, Japan) photography of the :w+vi 7l$  
lens. Grading of lens photographs in the BMES has been zK&1ti@wln  
previously described [12]. Briefly, masked grading was *2pf > UzL  
performed on the lens photographs using the Wisconsin 5RAhm0Op~.  
Cataract Grading System [13]. Cortical cataract and PSC @dx 8{oQ  
were assessed from the retroillumination photographs by u /] P  
estimating the percentage of the circular grid involved. [!4xInS  
Cortical cataract was defined when cortical opacity "YaT1` Kr  
involved at least 5% of the total lens area. PSC was defined ;dPaWS1D  
when opacity comprised at least 1% of the total lens area. +(PUiiP'"v  
Slit-lamp photographs were used to assess nuclear cataract n}t 9Nf_  
using the Wisconsin standard set of four lens photographs *@p"  
[13]. Nuclear cataract was defined when nuclear opacity  JJmW%%]i  
was at least as great as the standard 4 photograph. Any cataract k%X $@NP  
was defined to include persons who had previous mPHto-=fB  
cataract surgery as well as those with any of three cataract .$7RF!p  
types. Inter-grader reliability was high, with weighted ; 0Q" [[J  
kappa 0.82 for cortical cataract, 0.55 (simple kappa 0.75) *5 .wwV  
for nuclear cataract and 0.82 for PSC grading. The intragrader 7B=VH r  
reliability for nuclear cataract was assessed with `a83bF35  
simple kappa 0.83 for the senior grader who graded  %S%I W  
nuclear cataract at both surveys. All PSC cases were confirmed @6|< c  
by an ophthalmologist (PM). W=3#oX.GsU  
In cross-section I, 219 persons (6.0%) had missing or g$^-WmX\m  
ungradable Neitz photographs, leaving 3435 with photographs /# ]eVD  
available for cortical cataract and PSC assessment, Hy1$Kvub  
while 1153 (31.6%) had randomly missing or ungradable tjt^R$[@  
Topcon photographs due to a camera malfunction, leaving `g3AM%3  
2501 with photographs available for nuclear cataract DH%PkGn  
assessment. Comparison of characteristics between participants R~T}  
with and without Neitz or Topcon photographs in b>VV/j4!/  
cross-section I showed no statistically significant differences =Y81h-  
between the two groups, as reported previously sv?Fx;d  
[12]. In cross-section II, 441 persons (12.5%) had missing q)L4*O  
or ungradable Neitz photographs, leaving 3068 for cortical sYBmL]Hr  
cataract and PSC assessment, and 648 (18.5%) had >h)kbsSU0z  
missing or ungradable Topcon photographs, leaving 2860 eA86~M?<o  
for nuclear cataract assessment. E r%&y  
Data analysis was performed using the Statistical Analysis hPSMPbI  
System (SAS, SAS Institute, Cary, NC, USA). Age-adjusted xYCJO(&  
prevalence was calculated using direct standardization of E& i (T2c  
the cross-section II population to the cross-section I population. n"T ^  
We assessed age-specific prevalence using an cI'n[G  
interval of 5 years, so that participants within each age 'fl< ac,.  
group were independent between the two cross-sectional -f&vH_eK  
surveys. %K4M`R |2]  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 D$ K'Qk  
Page 3 of 7 !e$ZOYe  
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Results Lm~<BBp.  
Characteristics of the two survey populations have been ,\iHgsZ  
previously compared [14] and showed that age and sex (Fon!_$:  
distributions were similar. Table 1 compares participant sdZ$3oE.  
characteristics between the two cross-sections. Cross-section 17Cb{Q  
II participants generally had higher rates of diabetes, qsp.`9!  
hypertension, myopia and more users of inhaled steroids. rhbz|Uq  
Cataract prevalence rates in cross-sections I and II are p"p~Bx  
shown in Figure 1. The overall prevalence of cortical cataract '~&W'='b;  
was 23.8% and 23.7% in cross-sections I and II, 2$5">%?  
respectively (age-sex adjusted P = 0.81). Corresponding >-I <`y-H  
prevalence of PSC was 6.3% and 6.0% for the two crosssections Cjr]l!  
(age-sex adjusted P = 0.60). There was an KhfADqji|  
increased prevalence of nuclear cataract, from 18.7% in Bk~C$'x4  
cross-section I to 23.9% in cross-section II over the 6-year o13jd NQ-  
period (age-sex adjusted P < 0.001). Prevalence of any cataract |T""v_q  
(including persons who had cataract surgery), however, ] 5"k%v|  
was relatively stable (46.9% and 46.8% in crosssections "jum*<QZz  
I and II, respectively). hJ{u!:4  
After age-standardization, these prevalence rates remained =WT$\KYGv  
stable for cortical cataract (23.8% and 23.5% in the two z;>$["t]6  
surveys) and PSC (6.3% and 5.9%). The slightly increased *uyP+f2O  
prevalence of nuclear cataract (from 18.7% to 24.2%) was d-_V*rYU  
not altered. +_7a/3kh  
Table 2 shows the age-specific prevalence rates for cortical HXa[0VOx  
cataract, PSC and nuclear cataract in cross-sections I and :E.a.-  
II. A similar trend of increasing cataract prevalence with {1OxJn1hd  
increasing age was evident for all three types of cataract in jG[Vp b  
both surveys. Comparing the age-specific prevalence tRdf:F\X  
between the two surveys, a reduction in PSC prevalence in X!Z)V)@J8  
cross-section II was observed in the older age groups (≥ 75 9O3#d  
years). In contrast, increased nuclear cataract prevalence .Z [4:TS  
in cross-section II was observed in the older age groups (≥ #-;W|ib%z  
70 years). Age-specific cortical cataract prevalence was relatively 6#+&/ "*  
consistent between the two surveys, except for a GP%V(HhN  
reduction in prevalence observed in the 80–84 age group bXnUz?1!d  
and an increasing prevalence in the older age groups (≥ 85 F<I*? ${[  
years). \ZLi Y  
Similar gender differences in cataract prevalence were *2X~NJCt  
observed in both surveys (Table 3). Higher prevalence of o0R?vnA=  
cortical and nuclear cataract in women than men was evident [LnPV2@e  
but the difference was only significant for cortical <==uK>pET  
cataract (age-adjusted odds ratio, OR, for women 1.3, j hm3:;Z  
95% confidence intervals, CI, 1.1–1.5 in cross-section I 'Bue*  
and OR 1.4, 95% CI 1.1–1.6 in cross-section II). In con- .#QE*<T)]  
Table 1: Participant characteristics. $t;:"i>  
Characteristics Cross-section I Cross-section II S $p>sItO  
n % n % a*cWj }u  
Age (mean) (66.2) (66.7) +\T8`iCFB  
50–54 485 13.3 350 10.0 uy hh"[  
55–59 534 14.6 580 16.5 vkE`T5??  
60–64 638 17.5 600 17.1 k9x[( #  
65–69 671 18.4 639 18.2 4^W!,@W  
70–74 538 14.7 572 16.3 VP#KoX85  
75–79 422 11.6 407 11.6 MI `qzC*%  
80–84 230 6.3 226 6.4 `}?;Ow&2CY  
85–89 100 2.7 110 3.1 3lp'U&3`5  
90+ 36 1.0 24 0.7 T>B'T3or  
Female 2072 56.7 1998 57.0 aoey 5hts  
Ever Smokers 1784 51.2 1789 51.2 L(;$(k-/(  
Use of inhaled steroids 370 10.94 478 13.8^ zTa5 N  
History of: w#b@6d  
Diabetes 284 7.8 347 9.9^ hBX*02p   
Hypertension 1669 46.0 1825 52.2^ Vg NB^w  
Emmetropia* 1558 42.9 1478 42.2 @ual+=L  
Myopia* 442 12.2 495 14.1^ w,p'$WC*  
Hyperopia* 1633 45.0 1532 43.7 gQPw+0w  
n = number of persons affected <<0sv9qw1  
* best spherical equivalent refraction correction d=vuy   
^ P < 0.01 2f[;U"  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 R/oi6EKv  
Page 4 of 7 r:bJU1P1$s  
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t }:2##<"\t  
rast, men had slightly higher PSC prevalence than women T [SK>z  
in both cross-sections but the difference was not significant ;stjqTd  
(OR 1.1, 95% CI 0.8–1.4 for men in cross-section I -P}A26qB  
and OR 1.2, 95% 0.9–1.6 in cross-section II). 8* A%k1+  
Discussion @-sWXz*W  
Findings from two surveys of BMES cross-sectional populations !h.hJt  
with similar age and gender distribution showed aZb\uMePK  
that the prevalence of cortical cataract and PSC remained iN&oSpQ  
stable, while the prevalence of nuclear cataract appeared AXlVH%'  
to have increased. Comparison of age-specific prevalence, H7Q$k4\l  
with totally independent samples within each age group, q \@Zf}  
confirmed the robustness of our findings from the two \E?3nQM  
survey samples. Although lens photographs taken from X]=eC6M}:V  
the two surveys were graded for nuclear cataract by the O(/~cQ  
same graders, who documented a high inter- and intragrader yP{ 52%|+  
reliability, we cannot exclude the possibility that I;w!  
variations in photography, performed by different photographers, -FJ3;fP&  
may have contributed to the observed difference M 2hZ'  
in nuclear cataract prevalence. However, the overall A`uHZCwJ5  
Table 2: Age-specific prevalence of cataract types in cross sections I and II. I D_4M_G  
Cataract type Age (years) Cross-section I Cross-section II o-@01_j  
n % (95% CL)* n % (95% CL)* ZPH_s^  
Cortical 50–54 473 4.4 (2.6–6.3) 338 7.4 (4.6–10.2) @*y4uI6&  
55–59 522 9.2 (6.7–11.7) 542 9.0 (6.6–11.5) K;6#v%  
60–64 615 16.4 (13.5–19.4) 556 16.7 (13.6–19.8) :GIBB=D9  
65–69 653 26.2 (22.8–29.6) 581 23.6 (20.1–27.0) `^[k8Z(  
70–74 516 31.2 (27.2–35.2) 514 35.4 (31.3–39.6) N~, Ipf  
75–79 366 40.2 (35.1–45.2) 332 39.8 (34.5–45.1) Q` &#u#  
80–84 194 58.8 (51.8–65.8) 163 42.9 (35.3–50.6) }? _KZ)  
85–89 74 52.7 (41.1–64.4) 73 54.8 (43.1–66.5) VNTbjn]  
90+ 22 68.2 (47.0–89.3) 14 78.6 (54.0–103.2) 7Vy_Cec1  
PSC 50–54 474 2.7 (1.3–4.2) 338 2.4 (0.7–4.0) +ALrHFG  
55–59 522 2.9 (1.4–4.3) 541 2.6 (1.3–3.9) bJIYe ld  
60–64 616 4.6 (2.9–6.2) 548 5.7 (3.7–7.6) 9I/l+IS"X  
65–69 655 6.3 (4.4–8.1) 573 4.5 (2.8–6.3) -W9DH^EL<  
70–74 517 6.8 (4.6–8.9) 505 9.7 (7.1–12.3) ?(gha  
75–79 367 11.4 (8.2–14.7) 327 9.5 (6.3–12.7) xfeED^?  
80–84 196 12.2 (7.6–16.9) 155 10.3 (5.5–15.2) Q2 !GWz$  
85–89 74 18.9 (9.8–28.1) 69 11.6 (3.9–19.4) HF*0  
90+ 23 21.7 (3.5–40.0) 11 0.0 3*<@PXpK&  
Nuclear 50–54 323 1.6 (0.2–2.9) 331 0.9 (–0.2–1.9) kf'(u..G  
55–59 386 2.3 (0.8–3.8) 507 3.6 (1.9–5.2) @/ ^< 9  
60–64 453 5.3 (3.2–7.4) 501 11.6 (8.8–14.4) $0 .6No_|  
65–69 478 17.2 (13.8–20.1) 534 18.5 (15.2–21.9) d` ttWWPw  
70–74 392 27.6 (23.1–32.0) 453 36.0 (31.6–40.4) q~}oU5  
75–79 255 45.1 (39.0–51.3) 302 55.6 (50.0–61.3) w(V%EEk  
80–84 146 54.1 (45.9–62.3) 147 73.5 (66.3–80.7) i?!9%U!z4  
85–89 50 64.0 (50.2–77.8) 70 80.0 (70.4–89.6) ]jD\4\M}  
90+ 18 72.2 (49.3–95.1) 15 73.3 (48.0–98.7) .jD!+wv{9  
n = number of persons  oYN"L  
* 95% Confidence Limits O8 .iP+  
Cataract FMioguunrtea i1n ps rEeyvea lSetnucdey in cross-sections I and II of the Blue W+a/>U  
Cataract prevalence in cross-sections I and II of the Blue 'etA1]<N  
Mountains Eye Study. JlnmG<WLT  
0 lC#wh2B6  
10 J+t51B(a  
20 rhkKK_  
30 -u@ ^P7  
40 -7&ywgxl  
50 I-^sJ@V;  
cortical PSC nuclear any 1|{s8[;8  
cataract >s5}pkAv|e  
Cataract type /V*SI!C<f  
% {LjzkXs  
Cross-section I 4tkT\.  
Cross-section II In1{&sS  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 bIGcszWr  
Page 5 of 7 Z5TA4Q+Q  
(page number not for citation purposes)  7V5c`:"  
prevalence of any cataract (including cataract surgery) was 9xbT?$^  
relatively stable over the 6-year period. FQ 0&{ulb  
Although different population-based studies used different KWo Ps%G  
grading systems to assess cataract [15], the overall LC]0c)v#  
prevalence of the three cataract types were similar across =!L}/Dl  
different study populations [12,16-23]. Most studies have 1av#u:jy~>  
suggested that nuclear cataract is the most prevalent type SLEOc OAmD  
of cataract, followed by cortical cataract [16-20]. Ours and ?<jWEz=  
other studies reported that cortical cataract was the most 60|PVsmDm  
prevalent type [12,21-23]. K9ia|2f  
Our age-specific prevalence data show a reduction of EHq; eF  
15.9% in cortical cataract prevalence for the 80–84 year Ml c_w19C9  
age group, concordant with an increase in cataract surgery O\f`+Q`0  
prevalence by 9% in those aged 80+ years observed in the OB9E30  
same study population [10]. Although cortical cataract is sxr,] @  
thought to be the least likely cataract type leading to a cataract i tNuY<"  
surgery, this may not be the case in all older persons. MH)V=xU|)  
A relatively stable cortical cataract and PSC prevalence DNZ,rL:h  
over the 6-year period is expected. We cannot offer a b;D  
definitive explanation for the increase in nuclear cataract B?&0NpVD  
prevalence. A possible explanation could be that a moderate e 1XKlgl  
level of nuclear cataract causes less visual disturbance \dU.#^ryp  
than the other two types of cataract, thus for the oldest age  ;@k=9o]A  
groups, persons with nuclear cataract could have been less .aO6Y+Y  
likely to have surgery unless it is very dense or co-existing iLv -*%%  
with cortical cataract or PSC. Previous studies have shown tJu:N'=Dy  
that functional vision and reading performance were high S-mpob)  
in patients undergoing cataract surgery who had nuclear R\ 8[6H  
cataract only compared to those with mixed type of cataract P9m  
(nuclear and cortical) or PSC [24,25]. In addition, the !X: TieyVu  
overall prevalence of any cataract (including cataract surgery) yCR8c,'8  
was similar in the two cross-sections, which appears ?J + jv  
to support our speculation that in the oldest age group, - q9m@!L  
nuclear cataract may have been less likely to be operated =Pn"nkpML  
than the other two types of cataract. This could have UTE6U6  
resulted in an increased nuclear cataract prevalence (due m{ani/bt  
to less being operated), compensated by the decreased Hd;NvNS  
prevalence of cortical cataract and PSC (due to these being Tv'1 IE  
more likely to be operated), leading to stable overall prevalence DjaXJ?'  
of any cataract. 075IW"p'  
Possible selection bias arising from selective survival ,7cw%mQA  
among persons without cataract could have led to underestimation ):4)8@]5M  
of cataract prevalence in both surveys. We 5"40{3  
assume that such an underestimation occurred equally in !21G $ [H  
both surveys, and thus should not have influenced our CLZ j=J2  
assessment of temporal changes. y`$qcEw  
Measurement error could also have partially contributed sF)$<[w  
to the observed difference in nuclear cataract prevalence. vv)w@A:Vn)  
Assessment of nuclear cataract from photographs is a uP cx6X3]  
potentially subjective process that can be influenced by #t1? *4.p  
variations in photography (light exposure, focus and the `K0.6i [p  
slit-lamp angle when the photograph was taken) and ~)$R'=  
grading. Although we used the same Topcon slit-lamp  * ;Q#UH  
camera and the same two graders who graded photos % +  
from both surveys, we are still not able to exclude the possibility rZ.=Lq  
of a partial influence from photographic variation +W1l9n*  
on this result. (&)uWjq `  
A similar gender difference (women having a higher rate /QL<>g  
than men) in cortical cataract prevalence was observed in X`&Us  
both surveys. Our findings are in keeping with observations Xo(W\Pes  
from the Beaver Dam Eye Study [18], the Barbados RF6]_-  
Eye Study [22] and the Lens Opacities Case-Control 9`/ywt3Y  
Group [26]. It has been suggested that the difference G,Yctv  
could be related to hormonal factors [18,22]. A previous :-+][ [  
study on biochemical factors and cataract showed that a ~FI} [6Dd  
lower level of iron was associated with an increased risk of uCW}q. @4  
cortical cataract [27]. No interaction between sex and biochemical |@b|Q,  
factors were detected and no gender difference OmK0-fa/  
was assessed in this study [27]. The gender difference seen V^D 1:9i  
in cortical cataract could be related to relatively low iron V#1v5mWVx  
levels and low hemoglobin concentration usually seen in |C+ 5  
women [28]. Diabetes is a known risk factor for cortical FDFVhcr  
Table 3: Gender distribution of cataract types in cross-sections I and II. xXV15%&  
Cataract type Gender Cross-section I Cross-section II  wN0?~  
n % (95% CL)* n % (95% CL)* e6gj'GmY  
Cortical Male 1496 21.1 (19.0–23.1) 1328 20.4 (18.2–22.6) 3\<(!yY8  
Female 1939 25.9 (23.9–27.8) 1785 26.2 (24.2–28.3) bX`]<$dr3  
PSC Male 1500 6.5 (5.2–7.7) 1314 6.4 (5.1–7.7) aeLIs SEx  
Female 1944 6.2 (5.1–7.2) 1753 5.7 (4.6–6.7) M S|1Q@S9  
Nuclear Male 1106 17.6 (15.4–19.9) 1225 22.5 (20.1–24.8) RKs_k`N0  
Female 1395 19.5 (17.4–21.6) 1635 25.0 (22.9–27.1) j\.pS^+  
n = number of persons hA~5,K0b  
* 95% Confidence Limits CS"k0V44}  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 %HZ!s `w_  
Page 6 of 7 ;P|v'NNI  
(page number not for citation purposes) [nsTO5G$u  
cataract but in this particular population diabetes is more h2]G V-  
prevalent in men than women in all age groups [29]. Differential ^&c|z35F  
exposures to cataract risk factors or different dietary ]=0D~3o3  
or lifestyle patterns between men and women may x4_FG{AIu  
also be related to these observations and warrant further Ce3  
study. ybm&g( -\  
Conclusion ~65lDFY/  
In summary, in two population-based surveys 6 years @(tiPV  
apart, we have documented a relatively stable prevalence ##NowO  
of cortical cataract and PSC over the period. The observed !.={p8X-x  
overall increased nuclear cataract prevalence by 5% over a !3at(+4  
6-year period needs confirmation by future studies, and b(g?X ( &  
reasons for such an increase deserve further study. ^UpwVKdP  
Competing interests oU~e|  
The author(s) declare that they have no competing interests. PmE2T\{s!  
Authors' contributions [Hp"a^~r|  
AGT graded the photographs, performed literature search F a'2i<  
and wrote the first draft of the manuscript. JJW graded the <~qhy{hRn  
photographs, critically reviewed and modified the manuscript. |a Ht6F  
ER performed the statistical analysis and critically lhV'Q]s@6  
reviewed the manuscript. PM designed and directed the ?r6uEZ  
study, adjudicated cataract cases and critically reviewed _9zydtw  
and modified the manuscript. All authors read and v:] AS:  
approved the final manuscript. [R[Suf  
Acknowledgements # OQ(oyT  
This study was supported by the Australian National Health & Medical x-{awP  
Research Council, Canberra, Australia (Grant Nos 974159, 991407). The s8N\cOd#i  
abstract was presented at the Association for Research in Vision and Ophthalmology m)9qO7P  
(ARVO) meeting in Fort Lauderdale, Florida, USA, May 2005. )TcW.d6  
References _7zER6#}  
1. Congdon N, O'Colmain B, Klaver CC, Klein R, Munoz B, Friedman q[SUYb;,  
DS, Kempen J, Taylor HR, Mitchell P: Causes and prevalence of pYs"Y;%  
visual impairment among adults in the United States. Arch ~FV Z0%+,  
Ophthalmol 2004, 122(4):477-485. \YBY"J  
2. Rahmani B, Tielsch JM, Katz J, Gottsch J, Quigley H, Javitt J, Sommer 9f4#b8  
A: The cause-specific prevalence of visual impairment in an B/CP/Pfb  
urban population. The Baltimore Eye Survey. Ophthalmology r'q9N  
1996, 103:1721-1726. ) rs);Pl  
3. Keeffe JE, Konyama K, Taylor HR: Vision impairment in the s],+]<qX  
Pacific region. Br J Ophthalmol 2002, 86:605-610. 0:(@Y  
4. Reidy A, Minassian DC, Vafidis G, Joseph J, Farrow S, Wu J, Desai P, BI]%$r q  
Connolly A: Prevalence of serious eye disease and visual { O*maE"  
impairment in a north London population: population based, 3RP}lb  
cross sectional study. BMJ 1998, 316:1643-1646. bg)yl iX  
5. Resnikoff S, Pascolini D, Etya'ale D, Kocur I, Pararajasegaram R, r,x;q  
Pokharel GP, Mariotti SP: Global data on visual impairment in T(^<sjOs  
the year 2002. Bull World Health Organ 2004, 82:844-851. |vnfY; ;z1  
6. Pascolini D, Mariotti SP, Pokharel GP, Pararajasegaram R, Etya'ale D, /tf}8d  
Negrel AD, Resnikoff S: 2002 global update of available data on '7{0k{  
visual impairment: a compilation of population-based prevalence '@iS5Fni  
studies. Ophthalmic Epidemiol 2004, 11:67-115. dt  4_x1  
7. Rochtchina E, Mukesh BN, Wang JJ, McCarty CA, Taylor HR, Mitchell !58-3F%P  
P: Projected prevalence of age-related cataract and cataract Cj}1 )qWq  
surgery in Australia for the years 2001 and 2021: pooled data 6;GL> ))'  
from two population-based surveys. Clin Experiment Ophthalmol 7@m  
2003, 31:233-236. 13Ee"r  
8. Medicare Benefits Schedule Statistics [http://www.medicar ?/~7\ '|Z  
eaustralia.gov.au/statistics/dyn_mbs/forms/mbs_tab4.shtml] uM0 z%z5b  
9. Keeffe JE, Taylor HR: Cataract surgery in Australia 1985–94. %9=^#e+pE  
Aust N Z J Ophthalmol 1996, 24:313-317. x 1$tS#lS  
10. Tan AG, Wang JJ, Rochtchina E, Jakobsen K, Mitchell P: Increase in ?iUAzM8  
cataract surgery prevalence from 1992–1994 to 1997–2000: L;'+O u  
Analysis of two population cross-sections. Clin Experiment Ophthalmol %u43Pj  
2004, 32:284-288. c`y[V6q9  
11. Mitchell P, Smith W, Attebo K, Wang JJ: Prevalence of age-related -[x^z5Ee`  
maculopathy in Australia. The Blue Mountains Eye Study. yKa}U!$   
Ophthalmology 1995, 102:1450-1460. Ni GK| Z   
12. Mitchell P, Cumming RG, Attebo K, Panchapakesan J: Prevalence of >0SF79-RE  
cataract in Australia: the Blue Mountains eye study. Ophthalmology Y'Jb@l`$-  
1997, 104:581-588. ' d1E ~A  
13. Klein BEK, Magli YL, Neider MW, Klein R: Wisconsin system for classification JB'q_dS}  
of cataracts from photographs (protocol) Madison, WI; 1990. iR(A ^  
14. Foran S, Wang JJ, Mitchell P: Causes of visual impairment in two *#frbV?;  
older population cross-sections: the Blue Mountains Eye U^~K-!0  
Study. Ophthalmic Epidemiol 2003, 10:215-225. ."PR Z,  
15. Congdon N, Vingerling JR, Klein BE, West S, Friedman DS, Kempen J, "a6 wd  
O'Colmain B, Wu SY, Taylor HR: Prevalence of cataract and 2 ,;+)  
pseudophakia/aphakia among adults in the United States. 6U7z8NV&[  
Arch Ophthalmol 2004, 122:487-494. gV!Eotq  
16. Sperduto RD, Hiller R: The prevalence of nuclear, cortical, and <0R7uH  
posterior subcapsular lens opacities in a general population QM9~O#rL  
sample. Ophthalmology 1984, 91:815-818. ]ODC+q1  
17. Adamsons I, Munoz B, Enger C, Taylor HR: Prevalence of lens X c,UR .  
opacities in surgical and general populations. Arch Ophthalmol ||}|=Sz  
1991, 109:993-997. } ` Q'!_`  
18. Klein BE, Klein R, Linton KL: Prevalence of age-related lens  #d*mG =  
opacities in a population. The Beaver Dam Eye Study. Ophthalmology V@8 4Cb  
1992, 99:546-552. sxO_K^eD  
19. West SK, Munoz B, Schein OD, Duncan DD, Rubin GS: Racial differences nV McHN   
in lens opacities: the Salisbury Eye Evaluation (SEE) zY\v|l<T  
project. Am J Epidemiol 1998, 148:1033-1039. jY:(Tv3~  
20. Congdon N, West SK, Buhrmann RR, Kouzis A, Munoz B, Mkocha H: u|WX?@\  
Prevalence of the different types of age-related cataract in R/b)hP ~  
an African population. Invest Ophthalmol Vis Sci 2001, )wpBxJ;dB}  
42:2478-2482.  rc*3k  
21. Livingston PM, Guest CS, Stanislavsky Y, Lee S, Bayley S, Walker C, :I F&W=?9  
McKean C, Taylor HR: A population-based estimate of cataract I\Y/*u  
prevalence: the Melbourne Visual Impairment Project experience. %6L!JN  
Dev Ophthalmol 1994, 26:1-6. gJ c5Y  
22. Leske MC, Connell AM, Wu SY, Hyman L, Schachat A: Prevalence l8GziM{lp  
of lens opacities in the Barbados Eye Study. Arch Ophthalmol T!pWU*aB  
1997, 115:105-111. published erratum appears in Arch Ophthalmol ~{Tus.jk  
1997 Jul;115(7):931 <3 AkF# C9  
23. Seah SK, Wong TY, Foster PJ, Ng TP, Johnson GJ: Prevalence of o&;+!Si@T  
lens opacity in Chinese residents of Singapore: the tanjong y= cBpC  
pagar survey. Ophthalmology 2002, 109:2058-2064. {^"c>'R  
24. Stifter E, Sacu S, Weghaupt H, Konig F, Richter-Muksch S, Thaler A, nrwb6w j  
Velikay-Parel M, Radner W: Reading performance depending on -q(,}/Xf  
the type of cataract and its predictability on the visual outcome. 5^GUuFt5m  
J Cataract Refract Surg 2004, 30:1259-1267. 5$GE3IER8  
25. Stifter E, Sacu S, Weghaupt H: Functional vision with cataracts of ;r^8In@6  
different morphologies: comparative study. J Cataract Refract :5U(}\dL {  
Surg 2004, 30:1883-1891. V{{b^y  
26. Leske MC, Chylack LT Jr, Wu SY: The Lens Opacities Case-Control &UbNp8h  
Study. Risk factors for cataract. Arch Ophthalmol 1991, _ 97F  
109:244-251. 1reJ7b0  
27. Leske MC, Wu SY, Hyman L, Sperduto R, Underwood B, Chylack LT, hKQT,  
Milton RC, Srivastava S, Ansari N: Biochemical factors in the lens C% }FVO\c  
opacities. Case-control study. The Lens Opacities Case-Control ?%;7k'0"  
Study Group. Arch Ophthalmol 1995, 113:1113-1119. i?qS8h{  
28. Yip R, Johnson C, Dallman PR: Age-related changes in laboratory tE3!;  
values used in the diagnosis of anemia and iron deficiency. f@[q# }6  
Am J Clin Nutr 1984, 39:427-436. wcsUb 9(  
29. Mitchell P, Smith W, Wang JJ, Cumming RG, Leeder SR, Burnett L: EtcAU}9  
Diabetes in an older Australian population. Diabetes Res Clin k/j] *~"  
Pract 1998, 41:177-184. 3 5B 0L.R  
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