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楼主  发表于: 2009-06-04   

BMC Ophthalmology

BioMed Central ?@U7tNI  
Page 1 of 7 jd9GueV*(  
(page number not for citation purposes) h_K(8{1  
BMC Ophthalmology =%, ;=4w  
Research article Open Access )3_I-Ia  
Comparison of age-specific cataract prevalence in two !r:X`~\a  
population-based surveys 6 years apart =`f6@4H  
Ava Grace Tan†, Jie Jin Wang*†, Elena Rochtchina† and Paul Mitchell† tETT\y|'  
Address: Centre for Vision Research, Westmead Millennium Institute, Department of Ophthalmology, University of Sydney, Westmead Hospital, pK=$)<I"6  
Westmead, NSW, Australia wB6 ILTu1  
Email: Ava Grace Tan - ava_tan@wmi.usyd.edu.au; Jie Jin Wang* - jiejin_wang@wmi.usyd.edu.au; 'p=5hsG  
Elena Rochtchina - elena_rochtchina@wmi.usyd.edu.au; Paul Mitchell - paul_mitchell@wmi.usyd.edu.au mzuf l:-=  
* Corresponding author †Equal contributors c\i`=>%b@  
Abstract q\Cg2[nn2  
Background: In this study, we aimed to compare age-specific cortical, nuclear and posterior v)|[=  
subcapsular (PSC) cataract prevalence in two surveys 6 years apart. l[=7<F  
Methods: The Blue Mountains Eye Study examined 3654 participants (82.4% of those eligible) in t^0^He$Ot  
cross-section I (1992–4) and 3509 participants (75.1% of survivors and 85.2% of newly eligible) in l4+!H\2  
cross-section II (1997–2000, 66.5% overlap with cross-section I). Cataract was assessed from lens Pl_4;q!$  
photographs following the Wisconsin Cataract Grading System. Cortical cataract was defined if rrK&XP&  
cortical opacity comprised ≥ 5% of lens area. Nuclear cataract was defined if nuclear opacity ≥ 4`F(RweGx  
Wisconsin standard 4. PSC was defined if any present. Any cataract was defined to include persons a hi lp$v  
who had previous cataract surgery. Weighted kappa for inter-grader reliability was 0.82, 0.55 and ?bc-?<Xk  
0.82 for cortical, nuclear and PSC cataract, respectively. We assessed age-specific prevalence using >AsD6]  
an interval of 5 years, so that participants within each age group were independent between the `oP<mLxle  
two surveys.  Ad)Po  
Results: Age and gender distributions were similar between the two populations. The age-specific h^klP:Q  
prevalence of cortical (23.8% in 1st, 23.7% in 2nd) and PSC cataract (6.3%, 6.0%) was similar. The |cpBoU  
prevalence of nuclear cataract increased slightly from 18.7% to 23.9%. After age standardization, cjzhuH/y  
the similar prevalence of cortical (23.8%, 23.5%) and PSC cataract (6.3%, 5.9%), and the increased >$,A [|R  
prevalence of nuclear cataract (18.7%, 24.2%) remained. }} cz95  
Conclusion: In two surveys of two population-based samples with similar age and gender Bw-<xwD  
distributions, we found a relatively stable cortical and PSC cataract prevalence over a 6-year period. .<zW(PW  
The increased prevalence of nuclear cataract deserves further study. M<Mr L[*j  
Background NpV# zzE  
Age-related cataract is the leading cause of reversible visual x2p}0N  
impairment in older persons [1-6]. In Australia, it is 8hWB TUN  
estimated that by the year 2021, the number of people n:JWu0 ,h  
affected by cataract will increase by 63%, due to population IXb]\ )  
aging [7]. Surgical intervention is an effective treatment mG4myQ?$  
for cataract and normal vision (> 20/40) can usually :uhU<H<,f  
be restored with intraocular lens (IOL) implantation. x`8rR;N!  
Cataract surgery with IOL implantation is currently the P3|_R HIb  
most commonly performed, and is, arguably, the most .kpL?_  
cost effective surgical procedure worldwide. Performance SS?^-BI  
Published: 20 April 2006 lz>YjK:  
BMC Ophthalmology 2006, 6:17 doi:10.1186/1471-2415-6-17 6?y<F4  
Received: 14 December 2005 4;anoqiG\  
Accepted: 20 April 2006 /DOV/>@5%  
This article is available from: http://www.biomedcentral.com/1471-2415/6/17 noY~fq/U  
© 2006 Tan et al; licensee BioMed Central Ltd. j8p</gd  
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), ""cnZZ5)  
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ? b;_T,S[  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 6 &~ 8TH  
Page 2 of 7 Rh!B4oB4  
(page number not for citation purposes) .!uXhF'  
of this surgical procedure has been continuously increasing O;RsYs9  
in the last two decades. Data from the Australian e~ #;ux  
Health Insurance Commission has shown a steady @c&}\#;  
increase in Medicare claims for cataract surgery [8]. A 2.6- h LYy  
fold increase in the total number of cataract procedures D$C >ZF  
from 1985 to 1994 has been documented in Australia [9]. 8U,VpuQ:  
The rate of cataract surgery per thousand persons aged 65 RTN?[`  
years or older has doubled in the last 20 years [8,9]. In the sywSvnPuYZ  
Blue Mountains Eye Study population, we observed a onethird \Fd6Q_  
increase in cataract surgery prevalence over a mean VyQ@. Lm  
6-year interval, from 6% to nearly 8% in two cross-sectional ;pk4Voo$  
population-based samples with a similar age range #-76E  
[10]. Further increases in cataract surgery performance 5`su^  
would be expected as a result of improved surgical skills }yQ&[Mt  
and technique, together with extending cataract surgical !*2cK>`  
benefits to a greater number of older people and an ZL!,s#  
increased number of persons with surgery performed on @.IGOh  
both eyes. =Uy;8et  
Both the prevalence and incidence of age-related cataract :H9\nU1  
link directly to the demand for, and the outcome of, cataract xJCMxt2Y  
surgery and eye health care provision. This report R _#x  
aimed to assess temporal changes in the prevalence of cortical x`7Ch3`4}  
and nuclear cataract and posterior subcapsular cataract ;E,^bt<U  
(PSC) in two cross-sectional population-based I,[njlO:  
surveys 6 years apart. OS$ }ej\  
Methods tX'`4!{@+  
The Blue Mountains Eye Study (BMES) is a populationbased d|I_SI 1  
cohort study of common eye diseases and other i}&& rr  
health outcomes. The study involved eligible permanent b/#SkxW#S  
residents aged 49 years and older, living in two postcode p\;\hHai  
areas in the Blue Mountains, west of Sydney, Australia. }%8 :8_Ke  
Participants were identified through a census and were x*`S>_j27=  
invited to participate. The study was approved at each 9Hu;CKs  
stage of the data collection by the Human Ethics Committees "0*yD[2  
of the University of Sydney and the Western Sydney ! qVuhad.  
Area Health Service and adhered to the recommendations m!22tpb  
of the Declaration of Helsinki. Written informed consent 'iY~F0U  
was obtained from each participant. ]e t ]Vkg  
Details of the methods used in this study have been .j et0w  
described previously [11]. The baseline examinations -JKl\E  
(BMES cross-section I) were conducted during 1992– R"wBDWs  
1994 and included 3654 (82.4%) of 4433 eligible residents. <mrvuWg0  
Follow-up examinations (BMES IIA) were conducted 7$"A2x   
during 1997–1999, with 2335 (75.0% of BMES n%faD  
cross section I survivors) participating. A repeat census of gg0rkg  
the same area was performed in 1999 and identified 1378 @d&JtA  
newly eligible residents who moved into the area or the f:9b q}vH  
eligible age group. During 1999–2000, 1174 (85.2%) of TdU'L:<4l  
this group participated in an extension study (BMES IIB). |D% O`[k+  
BMES cross-section II thus includes BMES IIA (66.5%) \DiAfx<Ub  
and BMES IIB (33.5%) participants (n = 3509). bcR";cE  
Similar procedures were used for all stages of data collection QkF B \v  
at both surveys. A questionnaire was administered ~xa yGk  
including demographic, family and medical history. A .Ei#mG-=}&  
detailed eye examination included subjective refraction, 8aqH;|fG}  
slit-lamp (Topcon SL-7e camera, Topcon Optical Co, dfA2G<Uc  
Tokyo, Japan) and retroillumination (Neitz CT-R camera, dc dVB>D  
Neitz Instrument Co, Tokyo, Japan) photography of the j%U'mGx  
lens. Grading of lens photographs in the BMES has been DL*&e|:q  
previously described [12]. Briefly, masked grading was 'uW&AD p  
performed on the lens photographs using the Wisconsin w61*jnvi@  
Cataract Grading System [13]. Cortical cataract and PSC { v  [  
were assessed from the retroillumination photographs by 0iAQ;<*xi  
estimating the percentage of the circular grid involved. N!//m?}  
Cortical cataract was defined when cortical opacity M?d(-en  
involved at least 5% of the total lens area. PSC was defined ]IclA6  
when opacity comprised at least 1% of the total lens area. o zMn8@R  
Slit-lamp photographs were used to assess nuclear cataract uhm3}mWv  
using the Wisconsin standard set of four lens photographs S^x?<kYQau  
[13]. Nuclear cataract was defined when nuclear opacity <^w4+5sT/  
was at least as great as the standard 4 photograph. Any cataract K8JshF Ie  
was defined to include persons who had previous ~_F<"40  
cataract surgery as well as those with any of three cataract Lng@'Yr  
types. Inter-grader reliability was high, with weighted l[6lXR&|  
kappa 0.82 for cortical cataract, 0.55 (simple kappa 0.75) Zg4kO;r08  
for nuclear cataract and 0.82 for PSC grading. The intragrader z?Cez*.h>  
reliability for nuclear cataract was assessed with z.~jqxA9  
simple kappa 0.83 for the senior grader who graded '-BD.^!!  
nuclear cataract at both surveys. All PSC cases were confirmed 'si{6t|  
by an ophthalmologist (PM). 2BO&OX|X  
In cross-section I, 219 persons (6.0%) had missing or S "/-)_{  
ungradable Neitz photographs, leaving 3435 with photographs ]G~Z'fs<(  
available for cortical cataract and PSC assessment, cAn _:^  
while 1153 (31.6%) had randomly missing or ungradable v"l8[::  
Topcon photographs due to a camera malfunction, leaving * *.g^Pyc  
2501 with photographs available for nuclear cataract PDS?>Jg(  
assessment. Comparison of characteristics between participants MnP+L'|  
with and without Neitz or Topcon photographs in %R<xe.X  
cross-section I showed no statistically significant differences \ cdns;  
between the two groups, as reported previously 0$_WIk  
[12]. In cross-section II, 441 persons (12.5%) had missing 8 q>  
or ungradable Neitz photographs, leaving 3068 for cortical j XYr&F  
cataract and PSC assessment, and 648 (18.5%) had k3T374t1b  
missing or ungradable Topcon photographs, leaving 2860 rY M@e  
for nuclear cataract assessment. K,,'{j2#f  
Data analysis was performed using the Statistical Analysis VNs3.  
System (SAS, SAS Institute, Cary, NC, USA). Age-adjusted buDz]ec b  
prevalence was calculated using direct standardization of pjma < ^|F  
the cross-section II population to the cross-section I population. >[ g=G  
We assessed age-specific prevalence using an qYQ vjp  
interval of 5 years, so that participants within each age !R![:T\,  
group were independent between the two cross-sectional B h&dV%'  
surveys. O"#/>hmv-  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 #8$" 84&N.  
Page 3 of 7 R\-]$\1D  
(page number not for citation purposes) TkVqv v  
Results mNsd&Rk'  
Characteristics of the two survey populations have been T uC  
previously compared [14] and showed that age and sex 7nsovWp  
distributions were similar. Table 1 compares participant Tv9\` F[  
characteristics between the two cross-sections. Cross-section -`NzBuV$2,  
II participants generally had higher rates of diabetes, _M^^0kf  
hypertension, myopia and more users of inhaled steroids. \uO^w J}  
Cataract prevalence rates in cross-sections I and II are vOq N=bp  
shown in Figure 1. The overall prevalence of cortical cataract wB:<ICm  
was 23.8% and 23.7% in cross-sections I and II, ^9><qKbO  
respectively (age-sex adjusted P = 0.81). Corresponding \Yn0|j>  
prevalence of PSC was 6.3% and 6.0% for the two crosssections p K ^$^*#  
(age-sex adjusted P = 0.60). There was an (/E@.z[1  
increased prevalence of nuclear cataract, from 18.7% in 4K 8(H9(  
cross-section I to 23.9% in cross-section II over the 6-year D G|v' #  
period (age-sex adjusted P < 0.001). Prevalence of any cataract qC5IV}9`  
(including persons who had cataract surgery), however, ;%k C?Vzi  
was relatively stable (46.9% and 46.8% in crosssections P#V}l'j(<a  
I and II, respectively). >x6)AH.  
After age-standardization, these prevalence rates remained +"1-W> HV  
stable for cortical cataract (23.8% and 23.5% in the two T^{=c x9x9  
surveys) and PSC (6.3% and 5.9%). The slightly increased { `xC~B h  
prevalence of nuclear cataract (from 18.7% to 24.2%) was C Sz+cS  
not altered. bkz/V/Y  
Table 2 shows the age-specific prevalence rates for cortical y.s\MWvv>u  
cataract, PSC and nuclear cataract in cross-sections I and rHuzGSX54  
II. A similar trend of increasing cataract prevalence with #N%j9  
increasing age was evident for all three types of cataract in i|xz   
both surveys. Comparing the age-specific prevalence QjD=JC+  
between the two surveys, a reduction in PSC prevalence in !}5rd\  
cross-section II was observed in the older age groups (≥ 75 IM,4Si2  
years). In contrast, increased nuclear cataract prevalence ; .b^&h  
in cross-section II was observed in the older age groups (≥ -%Rbd0gVH\  
70 years). Age-specific cortical cataract prevalence was relatively ~)zxIO!  
consistent between the two surveys, except for a TQPrOs?  
reduction in prevalence observed in the 80–84 age group Qc=-M'9  
and an increasing prevalence in the older age groups (≥ 85 PS=q):R|  
years). f0R+Mz8{  
Similar gender differences in cataract prevalence were 0{u%J%;  
observed in both surveys (Table 3). Higher prevalence of 7 toI bC#  
cortical and nuclear cataract in women than men was evident 5:#|Op N  
but the difference was only significant for cortical $RunGaX!=N  
cataract (age-adjusted odds ratio, OR, for women 1.3, \  H#"  
95% confidence intervals, CI, 1.1–1.5 in cross-section I =-&h@mB;G  
and OR 1.4, 95% CI 1.1–1.6 in cross-section II). In con- > _G'o  
Table 1: Participant characteristics. =''b`T$  
Characteristics Cross-section I Cross-section II ,el[A`b  
n % n % U0iV E+)Bt  
Age (mean) (66.2) (66.7) /{[p?7x>  
50–54 485 13.3 350 10.0 FMhuCl 2  
55–59 534 14.6 580 16.5 <M}O&?N 8x  
60–64 638 17.5 600 17.1 !H<%X~|,  
65–69 671 18.4 639 18.2 YU!s;h  
70–74 538 14.7 572 16.3 4i5b.b U$  
75–79 422 11.6 407 11.6 |`s:&<W+kp  
80–84 230 6.3 226 6.4 Aon.Y Z  
85–89 100 2.7 110 3.1 -WR<tkK  
90+ 36 1.0 24 0.7 [7g-M/jvY  
Female 2072 56.7 1998 57.0 N9y+P sh  
Ever Smokers 1784 51.2 1789 51.2 wXKt)3dmu  
Use of inhaled steroids 370 10.94 478 13.8^ Zb|a\z8?  
History of: 5tzO=gO[  
Diabetes 284 7.8 347 9.9^ j)Kd'Va  
Hypertension 1669 46.0 1825 52.2^ TIR Is1  
Emmetropia* 1558 42.9 1478 42.2 8G9( )UF.  
Myopia* 442 12.2 495 14.1^ }$r]\v  
Hyperopia* 1633 45.0 1532 43.7 xU6dRjYhH9  
n = number of persons affected +P,ic*Kq*  
* best spherical equivalent refraction correction zr_L V_e  
^ P < 0.01 3K/ 'K[~  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 s.n:;8RibP  
Page 4 of 7 E*fa&G~s )  
(page number not for citation purposes) @Y>PtA&w*  
t H*P+>j&  
rast, men had slightly higher PSC prevalence than women :i@ $s/  
in both cross-sections but the difference was not significant :XPat9 3w  
(OR 1.1, 95% CI 0.8–1.4 for men in cross-section I {XUSw8W'  
and OR 1.2, 95% 0.9–1.6 in cross-section II). W}} ZP];  
Discussion 3Co1bY:  
Findings from two surveys of BMES cross-sectional populations HDKY7Yr  
with similar age and gender distribution showed % }Y&qT?  
that the prevalence of cortical cataract and PSC remained >!{8)ti  
stable, while the prevalence of nuclear cataract appeared wL^x9O|`p9  
to have increased. Comparison of age-specific prevalence, i[{*(Y$L   
with totally independent samples within each age group, %L7DC`  
confirmed the robustness of our findings from the two \Y!=O=za]  
survey samples. Although lens photographs taken from ~ Fl\ c-  
the two surveys were graded for nuclear cataract by the ITi#p%  
same graders, who documented a high inter- and intragrader ,Mi'NO   
reliability, we cannot exclude the possibility that l @@pXg3  
variations in photography, performed by different photographers, @PhAg  
may have contributed to the observed difference ,# .12Q!  
in nuclear cataract prevalence. However, the overall &jQqlQ j  
Table 2: Age-specific prevalence of cataract types in cross sections I and II. 3u ^wK  
Cataract type Age (years) Cross-section I Cross-section II % W|Sl  
n % (95% CL)* n % (95% CL)* -eS r  
Cortical 50–54 473 4.4 (2.6–6.3) 338 7.4 (4.6–10.2) R~hIoaiN  
55–59 522 9.2 (6.7–11.7) 542 9.0 (6.6–11.5) a|3+AWL%  
60–64 615 16.4 (13.5–19.4) 556 16.7 (13.6–19.8) =?wDQ:  
65–69 653 26.2 (22.8–29.6) 581 23.6 (20.1–27.0) },G rg~l  
70–74 516 31.2 (27.2–35.2) 514 35.4 (31.3–39.6) 0Q,Tc j  
75–79 366 40.2 (35.1–45.2) 332 39.8 (34.5–45.1) B9cWxe4R#  
80–84 194 58.8 (51.8–65.8) 163 42.9 (35.3–50.6) /d Ua  
85–89 74 52.7 (41.1–64.4) 73 54.8 (43.1–66.5) Nlwt}7  
90+ 22 68.2 (47.0–89.3) 14 78.6 (54.0–103.2) \_(0V"  
PSC 50–54 474 2.7 (1.3–4.2) 338 2.4 (0.7–4.0) eoQt87VCU  
55–59 522 2.9 (1.4–4.3) 541 2.6 (1.3–3.9) p} eO  
60–64 616 4.6 (2.9–6.2) 548 5.7 (3.7–7.6) \VW":+  
65–69 655 6.3 (4.4–8.1) 573 4.5 (2.8–6.3) o54=^@>O<j  
70–74 517 6.8 (4.6–8.9) 505 9.7 (7.1–12.3) /7,@q?v  
75–79 367 11.4 (8.2–14.7) 327 9.5 (6.3–12.7) $*P +   
80–84 196 12.2 (7.6–16.9) 155 10.3 (5.5–15.2) Jcs /i  
85–89 74 18.9 (9.8–28.1) 69 11.6 (3.9–19.4) ,nPnH1vb  
90+ 23 21.7 (3.5–40.0) 11 0.0 3!QXzT$E  
Nuclear 50–54 323 1.6 (0.2–2.9) 331 0.9 (–0.2–1.9) aM,g@'.=  
55–59 386 2.3 (0.8–3.8) 507 3.6 (1.9–5.2) v~._]f$:  
60–64 453 5.3 (3.2–7.4) 501 11.6 (8.8–14.4) vMn$lT@  
65–69 478 17.2 (13.8–20.1) 534 18.5 (15.2–21.9) een62-`  
70–74 392 27.6 (23.1–32.0) 453 36.0 (31.6–40.4) Fy$ C._C$  
75–79 255 45.1 (39.0–51.3) 302 55.6 (50.0–61.3) .N\t3\9}  
80–84 146 54.1 (45.9–62.3) 147 73.5 (66.3–80.7) X`eX+9  
85–89 50 64.0 (50.2–77.8) 70 80.0 (70.4–89.6) dpt P(H  
90+ 18 72.2 (49.3–95.1) 15 73.3 (48.0–98.7) oq1wU@n  
n = number of persons ^U,C])n  
* 95% Confidence Limits By}Z HK94I  
Cataract FMioguunrtea i1n ps rEeyvea lSetnucdey in cross-sections I and II of the Blue 78?{;iNv  
Cataract prevalence in cross-sections I and II of the Blue \X]I: 0^j  
Mountains Eye Study. >!o!rs  
0 dI=&gz  
10 B/3xV:Gy  
20 d+ $:u  
30 k{ZQM  
40 A4;~+L:M  
50 @KZW*-"  
cortical PSC nuclear any 3k8. 5W  
cataract !Ow M-t  
Cataract type c5i7mx:.  
% 3qV\XC+  
Cross-section I 9 uX 15a  
Cross-section II RcO.1@2  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 ^ ~Tn[w W_  
Page 5 of 7 W}(T5D" 3x  
(page number not for citation purposes) 65RD68a  
prevalence of any cataract (including cataract surgery) was ;MlPP)*k  
relatively stable over the 6-year period. bV#j@MJ~0  
Although different population-based studies used different @XcrHnH9  
grading systems to assess cataract [15], the overall nKTi"2dm  
prevalence of the three cataract types were similar across Wm)Id_  
different study populations [12,16-23]. Most studies have ?D_}',Wx  
suggested that nuclear cataract is the most prevalent type yy3`E}vX7  
of cataract, followed by cortical cataract [16-20]. Ours and \y7Gi}nI  
other studies reported that cortical cataract was the most xKepZ  
prevalent type [12,21-23]. KWi|7z(L=  
Our age-specific prevalence data show a reduction of C 8d9 (u  
15.9% in cortical cataract prevalence for the 80–84 year L,,*8  
age group, concordant with an increase in cataract surgery plNw>rFa  
prevalence by 9% in those aged 80+ years observed in the `sd H q  
same study population [10]. Although cortical cataract is ZHj7^y@P  
thought to be the least likely cataract type leading to a cataract r& :v(  
surgery, this may not be the case in all older persons. XuU>.T$]c  
A relatively stable cortical cataract and PSC prevalence Fa#5a'}I  
over the 6-year period is expected. We cannot offer a #wh[F"zX  
definitive explanation for the increase in nuclear cataract GQE7P()   
prevalence. A possible explanation could be that a moderate Kc> Rd  
level of nuclear cataract causes less visual disturbance 0 r;tI"  
than the other two types of cataract, thus for the oldest age -KqMSf&9  
groups, persons with nuclear cataract could have been less J DOs.w  
likely to have surgery unless it is very dense or co-existing X7MA>j3m  
with cortical cataract or PSC. Previous studies have shown ;YBk.} %  
that functional vision and reading performance were high W{ZJ^QAq/  
in patients undergoing cataract surgery who had nuclear ^Q!A4 qOQ  
cataract only compared to those with mixed type of cataract 7--E$ !9O,  
(nuclear and cortical) or PSC [24,25]. In addition, the C7&L9k~jf  
overall prevalence of any cataract (including cataract surgery) ykxAm\O  
was similar in the two cross-sections, which appears $bZ5@)E  
to support our speculation that in the oldest age group, |"eC0u  
nuclear cataract may have been less likely to be operated 5mm&l+N)  
than the other two types of cataract. This could have SkU9iW(k  
resulted in an increased nuclear cataract prevalence (due 81)i>]  
to less being operated), compensated by the decreased &uf|Le4  
prevalence of cortical cataract and PSC (due to these being \+C0Rv^^  
more likely to be operated), leading to stable overall prevalence OA[fQH#{lX  
of any cataract. 7DeBeY  
Possible selection bias arising from selective survival +.xK`_[M  
among persons without cataract could have led to underestimation acj-*I  
of cataract prevalence in both surveys. We M L7vP  
assume that such an underestimation occurred equally in !d95gq<=>  
both surveys, and thus should not have influenced our )X8N|W>vh  
assessment of temporal changes. V&lx0Dy  
Measurement error could also have partially contributed (!9+QXb'  
to the observed difference in nuclear cataract prevalence. H9WXp&  
Assessment of nuclear cataract from photographs is a 1buO&q!vn  
potentially subjective process that can be influenced by -N A2+].  
variations in photography (light exposure, focus and the ]y"=/Nu-Ja  
slit-lamp angle when the photograph was taken) and 0*AXd=)"*  
grading. Although we used the same Topcon slit-lamp ]q&NO(:kbq  
camera and the same two graders who graded photos R pT7Nr  
from both surveys, we are still not able to exclude the possibility &{ZUY3  
of a partial influence from photographic variation 1 r3} V7  
on this result.  nL[G@1nR  
A similar gender difference (women having a higher rate F]s:`4  
than men) in cortical cataract prevalence was observed in Uyd'uC  
both surveys. Our findings are in keeping with observations J_9[ x mM  
from the Beaver Dam Eye Study [18], the Barbados mo&9=TaG  
Eye Study [22] and the Lens Opacities Case-Control 'p[B`Ft3F  
Group [26]. It has been suggested that the difference g oJ'z|))  
could be related to hormonal factors [18,22]. A previous >G As&\4hs  
study on biochemical factors and cataract showed that a CW] Th-xc  
lower level of iron was associated with an increased risk of 6-+ wfrN2  
cortical cataract [27]. No interaction between sex and biochemical m!]J{OGG:  
factors were detected and no gender difference #G=AD /z  
was assessed in this study [27]. The gender difference seen DD`DU^o<  
in cortical cataract could be related to relatively low iron ^$[ iLX  
levels and low hemoglobin concentration usually seen in 8i)9ho<  
women [28]. Diabetes is a known risk factor for cortical 1X9J[5|ll  
Table 3: Gender distribution of cataract types in cross-sections I and II. vb}c)w dp?  
Cataract type Gender Cross-section I Cross-section II mmy/YP)  
n % (95% CL)* n % (95% CL)* .bj:tmz  
Cortical Male 1496 21.1 (19.0–23.1) 1328 20.4 (18.2–22.6) =r3g:j/>q  
Female 1939 25.9 (23.9–27.8) 1785 26.2 (24.2–28.3) 6;;2e> e  
PSC Male 1500 6.5 (5.2–7.7) 1314 6.4 (5.1–7.7) VmRfnH"  
Female 1944 6.2 (5.1–7.2) 1753 5.7 (4.6–6.7) m7i(0 jd +  
Nuclear Male 1106 17.6 (15.4–19.9) 1225 22.5 (20.1–24.8) ):y^ g:  
Female 1395 19.5 (17.4–21.6) 1635 25.0 (22.9–27.1) n^*,JL 9@  
n = number of persons pWP1$;8   
* 95% Confidence Limits >7~,w1t  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 m; L 3c(r.  
Page 6 of 7 )g }G{9M^  
(page number not for citation purposes) [70 5[  
cataract but in this particular population diabetes is more a2/Mf   
prevalent in men than women in all age groups [29]. Differential Gl[1K/,*  
exposures to cataract risk factors or different dietary {dn:1IcN  
or lifestyle patterns between men and women may H({m1v ~R  
also be related to these observations and warrant further KVUub'k  
study. ~$hR:I1  
Conclusion k!'+7 K.  
In summary, in two population-based surveys 6 years T8Q_JQ  
apart, we have documented a relatively stable prevalence i ^2A:6}?  
of cortical cataract and PSC over the period. The observed E&5S[n9{3  
overall increased nuclear cataract prevalence by 5% over a -Q&@P3x  
6-year period needs confirmation by future studies, and 0rm(i*Q  
reasons for such an increase deserve further study. TQ0ZBhd  
Competing interests 5 HE5$S  
The author(s) declare that they have no competing interests. P ?n k>  
Authors' contributions 1LAd5X  
AGT graded the photographs, performed literature search %d%?\jVb  
and wrote the first draft of the manuscript. JJW graded the E> $_ $'  
photographs, critically reviewed and modified the manuscript. lP*=4Jh  
ER performed the statistical analysis and critically G6G-qqXy6  
reviewed the manuscript. PM designed and directed the 65*Hf3~~  
study, adjudicated cataract cases and critically reviewed NJVkn~<  
and modified the manuscript. All authors read and P #`M8k  
approved the final manuscript. u3E =r  
Acknowledgements r/"^{0;F{W  
This study was supported by the Australian National Health & Medical kqxq'Aq)d  
Research Council, Canberra, Australia (Grant Nos 974159, 991407). The X%kJ3 {  
abstract was presented at the Association for Research in Vision and Ophthalmology >]C/ Q6  
(ARVO) meeting in Fort Lauderdale, Florida, USA, May 2005. z;Fz3s7  
References S Jc~E$5<  
1. Congdon N, O'Colmain B, Klaver CC, Klein R, Munoz B, Friedman >VQLC&u(  
DS, Kempen J, Taylor HR, Mitchell P: Causes and prevalence of PAtv#)h  
visual impairment among adults in the United States. Arch ~TeOl|!lE+  
Ophthalmol 2004, 122(4):477-485. \ym^~ Q|  
2. Rahmani B, Tielsch JM, Katz J, Gottsch J, Quigley H, Javitt J, Sommer \Q1&w2mw  
A: The cause-specific prevalence of visual impairment in an );6f8H@G  
urban population. The Baltimore Eye Survey. Ophthalmology b-#lKW so  
1996, 103:1721-1726. "5O>egt  
3. Keeffe JE, Konyama K, Taylor HR: Vision impairment in the }#%Y eCA?  
Pacific region. Br J Ophthalmol 2002, 86:605-610. z,7;+6*=L  
4. Reidy A, Minassian DC, Vafidis G, Joseph J, Farrow S, Wu J, Desai P, (Z[c7  
Connolly A: Prevalence of serious eye disease and visual %#eQN ~  
impairment in a north London population: population based, &=$f\O1Ty  
cross sectional study. BMJ 1998, 316:1643-1646. _~ei1 G.R  
5. Resnikoff S, Pascolini D, Etya'ale D, Kocur I, Pararajasegaram R, '@h  
Pokharel GP, Mariotti SP: Global data on visual impairment in XMT@<'fI  
the year 2002. Bull World Health Organ 2004, 82:844-851. j s"5{w&  
6. Pascolini D, Mariotti SP, Pokharel GP, Pararajasegaram R, Etya'ale D, %dq%+yw{%m  
Negrel AD, Resnikoff S: 2002 global update of available data on d|7LCW+HW  
visual impairment: a compilation of population-based prevalence ID! S}D  
studies. Ophthalmic Epidemiol 2004, 11:67-115. e@TwZ6l  
7. Rochtchina E, Mukesh BN, Wang JJ, McCarty CA, Taylor HR, Mitchell S-Vj$asv!  
P: Projected prevalence of age-related cataract and cataract 3oH/34jj  
surgery in Australia for the years 2001 and 2021: pooled data N[Ei%I  
from two population-based surveys. Clin Experiment Ophthalmol JJSE@$",\  
2003, 31:233-236. ~9vK 6;0  
8. Medicare Benefits Schedule Statistics [http://www.medicar nqUnDnP2c  
eaustralia.gov.au/statistics/dyn_mbs/forms/mbs_tab4.shtml] |pWu|M _'  
9. Keeffe JE, Taylor HR: Cataract surgery in Australia 1985–94. Ddg!1SF  
Aust N Z J Ophthalmol 1996, 24:313-317. X#JUorGp  
10. Tan AG, Wang JJ, Rochtchina E, Jakobsen K, Mitchell P: Increase in |Rkw/5  
cataract surgery prevalence from 1992–1994 to 1997–2000: E?P>s T3B  
Analysis of two population cross-sections. Clin Experiment Ophthalmol r~ f ;g9I  
2004, 32:284-288. NW`.7'aWT  
11. Mitchell P, Smith W, Attebo K, Wang JJ: Prevalence of age-related OW\vbWX  
maculopathy in Australia. The Blue Mountains Eye Study. =mZYBm,I Q  
Ophthalmology 1995, 102:1450-1460. jaKW[@<  
12. Mitchell P, Cumming RG, Attebo K, Panchapakesan J: Prevalence of $`/UG0rdC  
cataract in Australia: the Blue Mountains eye study. Ophthalmology ; YQB  
1997, 104:581-588. [R%*C9Y d  
13. Klein BEK, Magli YL, Neider MW, Klein R: Wisconsin system for classification )?(Ux1: w)  
of cataracts from photographs (protocol) Madison, WI; 1990. EC[]L'IL  
14. Foran S, Wang JJ, Mitchell P: Causes of visual impairment in two &;P\e  
older population cross-sections: the Blue Mountains Eye js <Up/1  
Study. Ophthalmic Epidemiol 2003, 10:215-225. WH1 " HO  
15. Congdon N, Vingerling JR, Klein BE, West S, Friedman DS, Kempen J, GU2TQx{V  
O'Colmain B, Wu SY, Taylor HR: Prevalence of cataract and J@_^]  
pseudophakia/aphakia among adults in the United States. Q*ELMib  
Arch Ophthalmol 2004, 122:487-494. , ftJw  
16. Sperduto RD, Hiller R: The prevalence of nuclear, cortical, and $9Bzq_!  
posterior subcapsular lens opacities in a general population K&NH?  
sample. Ophthalmology 1984, 91:815-818. 1 @t.J>  
17. Adamsons I, Munoz B, Enger C, Taylor HR: Prevalence of lens ;NdH]a {  
opacities in surgical and general populations. Arch Ophthalmol .-tR <{ g  
1991, 109:993-997. = wDXlAQ  
18. Klein BE, Klein R, Linton KL: Prevalence of age-related lens +<F3}]]  
opacities in a population. The Beaver Dam Eye Study. Ophthalmology $u~ui@kB  
1992, 99:546-552. X5J)1rL  
19. West SK, Munoz B, Schein OD, Duncan DD, Rubin GS: Racial differences L@AFt)U  
in lens opacities: the Salisbury Eye Evaluation (SEE) L{F]uz_[x  
project. Am J Epidemiol 1998, 148:1033-1039. 9]IZ3 fQX  
20. Congdon N, West SK, Buhrmann RR, Kouzis A, Munoz B, Mkocha H: 2h51zG#qd  
Prevalence of the different types of age-related cataract in |au`ph5  
an African population. Invest Ophthalmol Vis Sci 2001, "ufSHrZv  
42:2478-2482. LS<+V+o2%  
21. Livingston PM, Guest CS, Stanislavsky Y, Lee S, Bayley S, Walker C, 67Pmnad  
McKean C, Taylor HR: A population-based estimate of cataract _p0Yhju?  
prevalence: the Melbourne Visual Impairment Project experience. [=jZP,b&),  
Dev Ophthalmol 1994, 26:1-6. L$OZ]  
22. Leske MC, Connell AM, Wu SY, Hyman L, Schachat A: Prevalence Y"8@\73(R  
of lens opacities in the Barbados Eye Study. Arch Ophthalmol ]ASw%Lw)  
1997, 115:105-111. published erratum appears in Arch Ophthalmol W1"N Kg~4  
1997 Jul;115(7):931 HLV8_~gQPf  
23. Seah SK, Wong TY, Foster PJ, Ng TP, Johnson GJ: Prevalence of A 9BoH[is7  
lens opacity in Chinese residents of Singapore: the tanjong dyn)KDS  
pagar survey. Ophthalmology 2002, 109:2058-2064. *'8q?R?7g  
24. Stifter E, Sacu S, Weghaupt H, Konig F, Richter-Muksch S, Thaler A, Fik ;hB  
Velikay-Parel M, Radner W: Reading performance depending on RNB&!NC  
the type of cataract and its predictability on the visual outcome. 61kSCu  
J Cataract Refract Surg 2004, 30:1259-1267. t.;._'  
25. Stifter E, Sacu S, Weghaupt H: Functional vision with cataracts of aanS^t0  
different morphologies: comparative study. J Cataract Refract Wgte.K> /  
Surg 2004, 30:1883-1891. PsNrCe%e  
26. Leske MC, Chylack LT Jr, Wu SY: The Lens Opacities Case-Control Y3[KS;_fr9  
Study. Risk factors for cataract. Arch Ophthalmol 1991, -d4 v:Jab  
109:244-251. 6?M/7 1  
27. Leske MC, Wu SY, Hyman L, Sperduto R, Underwood B, Chylack LT, =L#&`s@)_  
Milton RC, Srivastava S, Ansari N: Biochemical factors in the lens 5Q8 H8!^  
opacities. Case-control study. The Lens Opacities Case-Control \v-I<"::  
Study Group. Arch Ophthalmol 1995, 113:1113-1119. sv% E5@  
28. Yip R, Johnson C, Dallman PR: Age-related changes in laboratory Sq,>^|v4&e  
values used in the diagnosis of anemia and iron deficiency. FNL S=4  
Am J Clin Nutr 1984, 39:427-436. eJ45:]_%I@  
29. Mitchell P, Smith W, Wang JJ, Cumming RG, Leeder SR, Burnett L: }gX hN"  
Diabetes in an older Australian population. Diabetes Res Clin Iv  
Pract 1998, 41:177-184. &)Qq%\EP4  
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