加入VIP 上传考博资料 您的流量 增加流量 考博报班 每日签到
   
主题 : BMC Ophthalmology
级别: 禁止发言
显示用户信息 
楼主  发表于: 2009-06-04   

BMC Ophthalmology

BioMed Central ~E2 KZm  
Page 1 of 7 ',JinE95  
(page number not for citation purposes) ] Zy5%gI  
BMC Ophthalmology KUlp"{a`,K  
Research article Open Access w"Gm; B4  
Comparison of age-specific cataract prevalence in two 8c9*\S  
population-based surveys 6 years apart -"' j7t:  
Ava Grace Tan†, Jie Jin Wang*†, Elena Rochtchina† and Paul Mitchell† I 8`VNA&b  
Address: Centre for Vision Research, Westmead Millennium Institute, Department of Ophthalmology, University of Sydney, Westmead Hospital, 3q\,$*D.  
Westmead, NSW, Australia ^:^9l1]  
Email: Ava Grace Tan - ava_tan@wmi.usyd.edu.au; Jie Jin Wang* - jiejin_wang@wmi.usyd.edu.au; iT gt}]L  
Elena Rochtchina - elena_rochtchina@wmi.usyd.edu.au; Paul Mitchell - paul_mitchell@wmi.usyd.edu.au aBNc(?ri  
* Corresponding author †Equal contributors Q ayPo]O  
Abstract _E@2ZnD2  
Background: In this study, we aimed to compare age-specific cortical, nuclear and posterior f!Y?S  
subcapsular (PSC) cataract prevalence in two surveys 6 years apart. Yg%I?  
Methods: The Blue Mountains Eye Study examined 3654 participants (82.4% of those eligible) in r*2+xDoEi  
cross-section I (1992–4) and 3509 participants (75.1% of survivors and 85.2% of newly eligible) in f e\$@-  
cross-section II (1997–2000, 66.5% overlap with cross-section I). Cataract was assessed from lens "O3tq =Q  
photographs following the Wisconsin Cataract Grading System. Cortical cataract was defined if nP$Ky1y G  
cortical opacity comprised ≥ 5% of lens area. Nuclear cataract was defined if nuclear opacity ≥ qouhuH_WtJ  
Wisconsin standard 4. PSC was defined if any present. Any cataract was defined to include persons &^ 1$^=  
who had previous cataract surgery. Weighted kappa for inter-grader reliability was 0.82, 0.55 and !Xf5e*1IS  
0.82 for cortical, nuclear and PSC cataract, respectively. We assessed age-specific prevalence using H1|?t+oP  
an interval of 5 years, so that participants within each age group were independent between the _.tVSV p  
two surveys. }~e8e   
Results: Age and gender distributions were similar between the two populations. The age-specific ]!?;@$wx  
prevalence of cortical (23.8% in 1st, 23.7% in 2nd) and PSC cataract (6.3%, 6.0%) was similar. The <wN}X#M  
prevalence of nuclear cataract increased slightly from 18.7% to 23.9%. After age standardization, :~"CuB/  
the similar prevalence of cortical (23.8%, 23.5%) and PSC cataract (6.3%, 5.9%), and the increased `i3NG1 v0  
prevalence of nuclear cataract (18.7%, 24.2%) remained. P+@/O  
Conclusion: In two surveys of two population-based samples with similar age and gender n{n52][J]  
distributions, we found a relatively stable cortical and PSC cataract prevalence over a 6-year period. _hAcJ{Y  
The increased prevalence of nuclear cataract deserves further study. 3`t#UY).F  
Background hZ?Rof  
Age-related cataract is the leading cause of reversible visual o[Q MTP  
impairment in older persons [1-6]. In Australia, it is Y2N>HK0  
estimated that by the year 2021, the number of people H%qsjB^  
affected by cataract will increase by 63%, due to population >*~L28Fyn  
aging [7]. Surgical intervention is an effective treatment s Ep"D+f  
for cataract and normal vision (> 20/40) can usually ` 06;   
be restored with intraocular lens (IOL) implantation. K -nF lPm\  
Cataract surgery with IOL implantation is currently the Z3"%`*Tmq-  
most commonly performed, and is, arguably, the most fiK6@,  
cost effective surgical procedure worldwide. Performance n,vct<&z@  
Published: 20 April 2006 Qf~vZtJ+J  
BMC Ophthalmology 2006, 6:17 doi:10.1186/1471-2415-6-17 sXLq*b?  
Received: 14 December 2005 bkOv2tZ  
Accepted: 20 April 2006 -]0OKE&  
This article is available from: http://www.biomedcentral.com/1471-2415/6/17 F+YZE[h%  
© 2006 Tan et al; licensee BioMed Central Ltd. ?&8^&brwG  
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), e>} s;H,  
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. l5S aT,%  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 ((YMVe  
Page 2 of 7 QyEn pZ8?a  
(page number not for citation purposes) z Xg3[orF  
of this surgical procedure has been continuously increasing zU5v /'h>d  
in the last two decades. Data from the Australian R5N%e%[  
Health Insurance Commission has shown a steady Lu?C- $a C  
increase in Medicare claims for cataract surgery [8]. A 2.6- k0OYJ/  
fold increase in the total number of cataract procedures -$pzl,^ h  
from 1985 to 1994 has been documented in Australia [9]. ;,hwZZA  
The rate of cataract surgery per thousand persons aged 65 !EvAB+`jLI  
years or older has doubled in the last 20 years [8,9]. In the XQY#716)  
Blue Mountains Eye Study population, we observed a onethird \o z#l'z  
increase in cataract surgery prevalence over a mean TJ10s%,V  
6-year interval, from 6% to nearly 8% in two cross-sectional I,E?h?6Y  
population-based samples with a similar age range Tr_ w]'  
[10]. Further increases in cataract surgery performance y*4=c _Z  
would be expected as a result of improved surgical skills GSoX<*i  
and technique, together with extending cataract surgical GA$V0YQX  
benefits to a greater number of older people and an W,K;6TZhh  
increased number of persons with surgery performed on _zR+i]9   
both eyes. (of#(I[m7  
Both the prevalence and incidence of age-related cataract !44/sr'  
link directly to the demand for, and the outcome of, cataract Lm iOhx  
surgery and eye health care provision. This report Xe3U`P7(  
aimed to assess temporal changes in the prevalence of cortical {0L1X6eg  
and nuclear cataract and posterior subcapsular cataract T.])diuvj-  
(PSC) in two cross-sectional population-based `fA@hK   
surveys 6 years apart. d?y4GkK  
Methods jte.Xy~g  
The Blue Mountains Eye Study (BMES) is a populationbased q;B4WL}  
cohort study of common eye diseases and other ?j'7l=94A  
health outcomes. The study involved eligible permanent oK9( /v  
residents aged 49 years and older, living in two postcode S4Pxc ]!  
areas in the Blue Mountains, west of Sydney, Australia. EGGWrl}1  
Participants were identified through a census and were GF"hx`zyJ  
invited to participate. The study was approved at each P9/q|>F  
stage of the data collection by the Human Ethics Committees kI,yU}<Fq  
of the University of Sydney and the Western Sydney r7RIRg_  
Area Health Service and adhered to the recommendations 0%3 2=k7O[  
of the Declaration of Helsinki. Written informed consent s,"]aew  
was obtained from each participant. mu\6z_e  
Details of the methods used in this study have been 7!e vm;A  
described previously [11]. The baseline examinations ADz ^\  
(BMES cross-section I) were conducted during 1992– Ja|5 @  
1994 and included 3654 (82.4%) of 4433 eligible residents. \Q {m9fE  
Follow-up examinations (BMES IIA) were conducted I )~GZ  
during 1997–1999, with 2335 (75.0% of BMES P:hBt\5B  
cross section I survivors) participating. A repeat census of 6gkV*|U,e  
the same area was performed in 1999 and identified 1378 1Rt33\1J0  
newly eligible residents who moved into the area or the 48J@C vU  
eligible age group. During 1999–2000, 1174 (85.2%) of '<gI8W</  
this group participated in an extension study (BMES IIB). g!|=%(G=  
BMES cross-section II thus includes BMES IIA (66.5%) <3oWEm  
and BMES IIB (33.5%) participants (n = 3509). el& 0}`K  
Similar procedures were used for all stages of data collection  Z< 1  
at both surveys. A questionnaire was administered S~<$H y*kh  
including demographic, family and medical history. A 99]R$eT8  
detailed eye examination included subjective refraction, kF3k7,.8&  
slit-lamp (Topcon SL-7e camera, Topcon Optical Co, 'Y?"{HZ  
Tokyo, Japan) and retroillumination (Neitz CT-R camera, 1]d!~  
Neitz Instrument Co, Tokyo, Japan) photography of the &U{#Kt5q  
lens. Grading of lens photographs in the BMES has been @hl.lq  
previously described [12]. Briefly, masked grading was ajve~8 /&  
performed on the lens photographs using the Wisconsin 32(^Te]:  
Cataract Grading System [13]. Cortical cataract and PSC ]v?@g:i E  
were assessed from the retroillumination photographs by Z/G ev"p  
estimating the percentage of the circular grid involved. t Cw<Ip  
Cortical cataract was defined when cortical opacity  52Yq  
involved at least 5% of the total lens area. PSC was defined +<'Ev~  
when opacity comprised at least 1% of the total lens area. "N;`1ce  
Slit-lamp photographs were used to assess nuclear cataract B[qzUD*P_n  
using the Wisconsin standard set of four lens photographs !d'GE`w T  
[13]. Nuclear cataract was defined when nuclear opacity f<GhkDPm>?  
was at least as great as the standard 4 photograph. Any cataract []D&bYpv  
was defined to include persons who had previous UJ%R   
cataract surgery as well as those with any of three cataract  pD(j'[  
types. Inter-grader reliability was high, with weighted 5b5x!do  
kappa 0.82 for cortical cataract, 0.55 (simple kappa 0.75) L]yS[UN$  
for nuclear cataract and 0.82 for PSC grading. The intragrader 1v#%Ei$6`t  
reliability for nuclear cataract was assessed with Cwr~HY  
simple kappa 0.83 for the senior grader who graded 5CuuG<0  
nuclear cataract at both surveys. All PSC cases were confirmed a,Sw4yJ!Q  
by an ophthalmologist (PM). y+Ra4G#/}  
In cross-section I, 219 persons (6.0%) had missing or }pDqe;a{  
ungradable Neitz photographs, leaving 3435 with photographs 8."]//V  
available for cortical cataract and PSC assessment, a@8v^G  
while 1153 (31.6%) had randomly missing or ungradable v/@^Q1 G/:  
Topcon photographs due to a camera malfunction, leaving "33Fv9C#bK  
2501 with photographs available for nuclear cataract %) /s;Q,  
assessment. Comparison of characteristics between participants [v7F1@6b  
with and without Neitz or Topcon photographs in Q_1:tW &  
cross-section I showed no statistically significant differences 'SO %)B  
between the two groups, as reported previously &\#sI9  
[12]. In cross-section II, 441 persons (12.5%) had missing @X%C>iYa9  
or ungradable Neitz photographs, leaving 3068 for cortical j_/>A=OD  
cataract and PSC assessment, and 648 (18.5%) had -^K"Z P1  
missing or ungradable Topcon photographs, leaving 2860 z-BXd  
for nuclear cataract assessment. 9"NF/)_  
Data analysis was performed using the Statistical Analysis %fc !2E9|  
System (SAS, SAS Institute, Cary, NC, USA). Age-adjusted 8G9s<N}5&u  
prevalence was calculated using direct standardization of Bz^jw>1b  
the cross-section II population to the cross-section I population. 67VL@ ]  
We assessed age-specific prevalence using an hmvfw:Nq4  
interval of 5 years, so that participants within each age &[_g6OL  
group were independent between the two cross-sectional G"klu  
surveys. y.anl  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 We Jl4wF  
Page 3 of 7 Z"Zmo>cV4  
(page number not for citation purposes) hM@ HA  
Results :Uz|3gq  
Characteristics of the two survey populations have been |^0XYBxQ  
previously compared [14] and showed that age and sex ccB&O _  
distributions were similar. Table 1 compares participant +GG9^:<yr  
characteristics between the two cross-sections. Cross-section Y}x>t* I  
II participants generally had higher rates of diabetes, 46$._h P  
hypertension, myopia and more users of inhaled steroids. 2!0c4a^z  
Cataract prevalence rates in cross-sections I and II are yaD~1"GA'O  
shown in Figure 1. The overall prevalence of cortical cataract <_h~w}  
was 23.8% and 23.7% in cross-sections I and II, : imW\@u  
respectively (age-sex adjusted P = 0.81). Corresponding )n+Lo&C<  
prevalence of PSC was 6.3% and 6.0% for the two crosssections s2teym,uG  
(age-sex adjusted P = 0.60). There was an hq%?=2'9?  
increased prevalence of nuclear cataract, from 18.7% in uH/J]zKR  
cross-section I to 23.9% in cross-section II over the 6-year %kv0We fs  
period (age-sex adjusted P < 0.001). Prevalence of any cataract Qr1"Tk7s  
(including persons who had cataract surgery), however, Cf TfL3(J  
was relatively stable (46.9% and 46.8% in crosssections ADS9DiX/  
I and II, respectively). M}d_I+  
After age-standardization, these prevalence rates remained AB=daie  
stable for cortical cataract (23.8% and 23.5% in the two A$<.a'&T!  
surveys) and PSC (6.3% and 5.9%). The slightly increased X59: C3c  
prevalence of nuclear cataract (from 18.7% to 24.2%) was Q7*SE%H  
not altered. qo p^;~  
Table 2 shows the age-specific prevalence rates for cortical &7<TAo;O  
cataract, PSC and nuclear cataract in cross-sections I and RLw;(*(g  
II. A similar trend of increasing cataract prevalence with { WIJC ',Y  
increasing age was evident for all three types of cataract in }B8IBveu  
both surveys. Comparing the age-specific prevalence YwteZSbp6M  
between the two surveys, a reduction in PSC prevalence in 1HXjN~XF  
cross-section II was observed in the older age groups (≥ 75 ozAS[B6  
years). In contrast, increased nuclear cataract prevalence 8WtsKOno  
in cross-section II was observed in the older age groups (≥ @HQ`~C#Z'  
70 years). Age-specific cortical cataract prevalence was relatively {kp"nl$<  
consistent between the two surveys, except for a pi /g H  
reduction in prevalence observed in the 80–84 age group Nd`%5%'::  
and an increasing prevalence in the older age groups (≥ 85 }'""(,2  
years). D&/kCi=R  
Similar gender differences in cataract prevalence were t0o`-d(  
observed in both surveys (Table 3). Higher prevalence of .l>77zM6  
cortical and nuclear cataract in women than men was evident X*M#FT-  
but the difference was only significant for cortical } E0,z  
cataract (age-adjusted odds ratio, OR, for women 1.3, *FC=X)_&W  
95% confidence intervals, CI, 1.1–1.5 in cross-section I PK;*u,V  
and OR 1.4, 95% CI 1.1–1.6 in cross-section II). In con- Ans cr  
Table 1: Participant characteristics. K AC6Snu1  
Characteristics Cross-section I Cross-section II <Fi%iA  
n % n % vI2^tX 9  
Age (mean) (66.2) (66.7) $>GgB`   
50–54 485 13.3 350 10.0 _9Jh L:cY  
55–59 534 14.6 580 16.5 6I1,:nLL<  
60–64 638 17.5 600 17.1 (5R?#vj  
65–69 671 18.4 639 18.2 7[I}*3Q'  
70–74 538 14.7 572 16.3 X}tVmO?  
75–79 422 11.6 407 11.6 $UgA0]q n  
80–84 230 6.3 226 6.4 3D` YZ#M  
85–89 100 2.7 110 3.1 Q,p}:e  
90+ 36 1.0 24 0.7 Kz>3 ic$I  
Female 2072 56.7 1998 57.0 ?*E'^~,H)  
Ever Smokers 1784 51.2 1789 51.2 <1FC%f/  
Use of inhaled steroids 370 10.94 478 13.8^ &GlwC%$S  
History of: '@p['#\uI  
Diabetes 284 7.8 347 9.9^ o>/YAX:.!T  
Hypertension 1669 46.0 1825 52.2^ /x5rf  
Emmetropia* 1558 42.9 1478 42.2 #gp,V#T  
Myopia* 442 12.2 495 14.1^ *8#i$w11M  
Hyperopia* 1633 45.0 1532 43.7 p$h4u_  
n = number of persons affected {.QEc0-  
* best spherical equivalent refraction correction .Jt[(;  
^ P < 0.01 lD"(MQV@0  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 cJ1#ge%4  
Page 4 of 7 TYJ:!  
(page number not for citation purposes) T{Sb^-H#X  
t `0P$ #5?  
rast, men had slightly higher PSC prevalence than women kMtwiB|7j  
in both cross-sections but the difference was not significant 2_zp:v  
(OR 1.1, 95% CI 0.8–1.4 for men in cross-section I Xb{ [c+.  
and OR 1.2, 95% 0.9–1.6 in cross-section II). |P -8HlOr  
Discussion VJdIHsI  
Findings from two surveys of BMES cross-sectional populations jFA{+Yr1  
with similar age and gender distribution showed ^@qvl%j  
that the prevalence of cortical cataract and PSC remained \|E^v6E%0  
stable, while the prevalence of nuclear cataract appeared -PS#Z0>  
to have increased. Comparison of age-specific prevalence, G8r``{C!  
with totally independent samples within each age group, n@ U n  
confirmed the robustness of our findings from the two :{IO=^D=$  
survey samples. Although lens photographs taken from HYD"#m'TkB  
the two surveys were graded for nuclear cataract by the R }lsnX<  
same graders, who documented a high inter- and intragrader NGOqy+Ty{f  
reliability, we cannot exclude the possibility that |!"2fI  
variations in photography, performed by different photographers, q|8{@EMT  
may have contributed to the observed difference iVd.f A  
in nuclear cataract prevalence. However, the overall df n9!h  
Table 2: Age-specific prevalence of cataract types in cross sections I and II. 0#ClWynjRO  
Cataract type Age (years) Cross-section I Cross-section II x\J#]d.  
n % (95% CL)* n % (95% CL)* Hd, p!_  
Cortical 50–54 473 4.4 (2.6–6.3) 338 7.4 (4.6–10.2) Db6om7N  
55–59 522 9.2 (6.7–11.7) 542 9.0 (6.6–11.5) 'A:x/iv}^  
60–64 615 16.4 (13.5–19.4) 556 16.7 (13.6–19.8) `;>= '"O!\  
65–69 653 26.2 (22.8–29.6) 581 23.6 (20.1–27.0) DSt]{fl`P  
70–74 516 31.2 (27.2–35.2) 514 35.4 (31.3–39.6) tUgEeh6  
75–79 366 40.2 (35.1–45.2) 332 39.8 (34.5–45.1) NMww>80  
80–84 194 58.8 (51.8–65.8) 163 42.9 (35.3–50.6) ~M\I;8ne  
85–89 74 52.7 (41.1–64.4) 73 54.8 (43.1–66.5) v@wb"jdFi$  
90+ 22 68.2 (47.0–89.3) 14 78.6 (54.0–103.2) 7^Ns&Q  
PSC 50–54 474 2.7 (1.3–4.2) 338 2.4 (0.7–4.0) ?c7*_<W 5  
55–59 522 2.9 (1.4–4.3) 541 2.6 (1.3–3.9) KyzFnVH3)  
60–64 616 4.6 (2.9–6.2) 548 5.7 (3.7–7.6) ?}m']4p  
65–69 655 6.3 (4.4–8.1) 573 4.5 (2.8–6.3) jq+A-T}@  
70–74 517 6.8 (4.6–8.9) 505 9.7 (7.1–12.3) dlG=Vq&Y  
75–79 367 11.4 (8.2–14.7) 327 9.5 (6.3–12.7) jiYmb8Q4D  
80–84 196 12.2 (7.6–16.9) 155 10.3 (5.5–15.2) !>>f(t4  
85–89 74 18.9 (9.8–28.1) 69 11.6 (3.9–19.4) ;\[(- )f!=  
90+ 23 21.7 (3.5–40.0) 11 0.0 1c;6xc,ub  
Nuclear 50–54 323 1.6 (0.2–2.9) 331 0.9 (–0.2–1.9) &[At`Nw71  
55–59 386 2.3 (0.8–3.8) 507 3.6 (1.9–5.2) YSj+\Z$(  
60–64 453 5.3 (3.2–7.4) 501 11.6 (8.8–14.4) -CRQ&#p1]  
65–69 478 17.2 (13.8–20.1) 534 18.5 (15.2–21.9) Y;)dct  
70–74 392 27.6 (23.1–32.0) 453 36.0 (31.6–40.4) ixV0|P8,c  
75–79 255 45.1 (39.0–51.3) 302 55.6 (50.0–61.3) }=|!:k iE  
80–84 146 54.1 (45.9–62.3) 147 73.5 (66.3–80.7) !H2QjW  
85–89 50 64.0 (50.2–77.8) 70 80.0 (70.4–89.6) uio@r^Xz  
90+ 18 72.2 (49.3–95.1) 15 73.3 (48.0–98.7) :Dd$i_3=  
n = number of persons (%U@3._  
* 95% Confidence Limits Z( 9 u<  
Cataract FMioguunrtea i1n ps rEeyvea lSetnucdey in cross-sections I and II of the Blue !o>H1#2l  
Cataract prevalence in cross-sections I and II of the Blue rvyr xw%[  
Mountains Eye Study. e{KByFl  
0 F {B\kq8  
10 7#~+@'Oe  
20 3( ]M{4j  
30 p2N:;lXM  
40 Cn_$l>  
50 wP57Pf0  
cortical PSC nuclear any Hk7q{`:N  
cataract 5P .qXA"D  
Cataract type *-12VIG'H  
%  iL= m{  
Cross-section I @m?QR(LJ  
Cross-section II '<R>E:5  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 J>^\oAgpE  
Page 5 of 7 ms_ VM>l  
(page number not for citation purposes) HK)cKzG[s!  
prevalence of any cataract (including cataract surgery) was O'GG Ti]e  
relatively stable over the 6-year period. KvQ,;A  
Although different population-based studies used different -AYA~O(&  
grading systems to assess cataract [15], the overall XM<KF &pVB  
prevalence of the three cataract types were similar across ez3Z3t`  
different study populations [12,16-23]. Most studies have kGkA:g:  
suggested that nuclear cataract is the most prevalent type l/ y]nw  
of cataract, followed by cortical cataract [16-20]. Ours and iU+nqY'  
other studies reported that cortical cataract was the most ~dHM4lGY  
prevalent type [12,21-23]. WS2os Bc  
Our age-specific prevalence data show a reduction of q@hp.(V  
15.9% in cortical cataract prevalence for the 80–84 year 39 Y(!q  
age group, concordant with an increase in cataract surgery z NSu  
prevalence by 9% in those aged 80+ years observed in the <As9>5|%  
same study population [10]. Although cortical cataract is '<iK*[NW  
thought to be the least likely cataract type leading to a cataract /?/#B `  
surgery, this may not be the case in all older persons. +KEkmXZ  
A relatively stable cortical cataract and PSC prevalence k#}g,0@  
over the 6-year period is expected. We cannot offer a @^ ik[9^H  
definitive explanation for the increase in nuclear cataract ~^)^q 8  
prevalence. A possible explanation could be that a moderate jy2IZ o  
level of nuclear cataract causes less visual disturbance +~nzii3  
than the other two types of cataract, thus for the oldest age Xj+q~4{|vt  
groups, persons with nuclear cataract could have been less 02AI%OOH  
likely to have surgery unless it is very dense or co-existing 3}1ssU"T  
with cortical cataract or PSC. Previous studies have shown s|bM%!$1  
that functional vision and reading performance were high EA<}[4#jS  
in patients undergoing cataract surgery who had nuclear !.5),2  
cataract only compared to those with mixed type of cataract 7@%'wy&A  
(nuclear and cortical) or PSC [24,25]. In addition, the IO.<q,pP!_  
overall prevalence of any cataract (including cataract surgery) ! o, 5h|\  
was similar in the two cross-sections, which appears S\NL+V?7h  
to support our speculation that in the oldest age group, ~:sE:9$z  
nuclear cataract may have been less likely to be operated ;/AG@$)  
than the other two types of cataract. This could have J?:[$C5  
resulted in an increased nuclear cataract prevalence (due YJ7V`N p  
to less being operated), compensated by the decreased |I[7,`C~  
prevalence of cortical cataract and PSC (due to these being pF=g||gS  
more likely to be operated), leading to stable overall prevalence 7_KhV  
of any cataract. : //U^sFL  
Possible selection bias arising from selective survival {GqXP0'  
among persons without cataract could have led to underestimation t]_S  
of cataract prevalence in both surveys. We K3$` Kv>I  
assume that such an underestimation occurred equally in J>S3sP  
both surveys, and thus should not have influenced our 2C+(":=}  
assessment of temporal changes. $.e)  
Measurement error could also have partially contributed ~0tdfK0c  
to the observed difference in nuclear cataract prevalence. 8LM #WIm?  
Assessment of nuclear cataract from photographs is a ( 76{2  
potentially subjective process that can be influenced by j^u[F"  
variations in photography (light exposure, focus and the &  &RA4  
slit-lamp angle when the photograph was taken) and ij)Cm]4(2  
grading. Although we used the same Topcon slit-lamp nTnRGf\T  
camera and the same two graders who graded photos s^|\9%WD  
from both surveys, we are still not able to exclude the possibility KjR4=9MD  
of a partial influence from photographic variation ,a(O`##Bn  
on this result. m3 IP7h'  
A similar gender difference (women having a higher rate eO4)|tW  
than men) in cortical cataract prevalence was observed in j]> uZalr  
both surveys. Our findings are in keeping with observations F,Fo}YQX  
from the Beaver Dam Eye Study [18], the Barbados :k"rhI  
Eye Study [22] and the Lens Opacities Case-Control 1i?=JAFfM  
Group [26]. It has been suggested that the difference 7!d$M{0"  
could be related to hormonal factors [18,22]. A previous X=_Z(;<&  
study on biochemical factors and cataract showed that a X5E '*W  
lower level of iron was associated with an increased risk of Zq?_dIX %  
cortical cataract [27]. No interaction between sex and biochemical X ]s"5ju|t  
factors were detected and no gender difference  nP_=GI  
was assessed in this study [27]. The gender difference seen kEAhTh&g*  
in cortical cataract could be related to relatively low iron %h*5xB]Tt  
levels and low hemoglobin concentration usually seen in 0 BC`iql5  
women [28]. Diabetes is a known risk factor for cortical Ow3a0cF[9  
Table 3: Gender distribution of cataract types in cross-sections I and II. kMS5h~D[  
Cataract type Gender Cross-section I Cross-section II ONWO`XD  
n % (95% CL)* n % (95% CL)* 8t``NZ[  
Cortical Male 1496 21.1 (19.0–23.1) 1328 20.4 (18.2–22.6) YC)hX'A\  
Female 1939 25.9 (23.9–27.8) 1785 26.2 (24.2–28.3) R~c1)[[E  
PSC Male 1500 6.5 (5.2–7.7) 1314 6.4 (5.1–7.7) #:W%,$ 9\P  
Female 1944 6.2 (5.1–7.2) 1753 5.7 (4.6–6.7) B!`\L!  
Nuclear Male 1106 17.6 (15.4–19.9) 1225 22.5 (20.1–24.8) :0dfB&7  
Female 1395 19.5 (17.4–21.6) 1635 25.0 (22.9–27.1) { y/-:=S)A  
n = number of persons %gTVW!q  
* 95% Confidence Limits 51/sTx<Z}  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 _S<?t9mS  
Page 6 of 7 \*9Ua/H  
(page number not for citation purposes)  7kM4Ei  
cataract but in this particular population diabetes is more y*|L:!   
prevalent in men than women in all age groups [29]. Differential &G=0  
exposures to cataract risk factors or different dietary W^|J/Y48  
or lifestyle patterns between men and women may 4g'}h`kh   
also be related to these observations and warrant further LH.%\TMN$  
study. .' IeHh  
Conclusion 6'vi68  
In summary, in two population-based surveys 6 years QB9A-U <J  
apart, we have documented a relatively stable prevalence |P~q/Wff  
of cortical cataract and PSC over the period. The observed EFv4=OWB  
overall increased nuclear cataract prevalence by 5% over a N=<=dp(  
6-year period needs confirmation by future studies, and 5"e+& zU~f  
reasons for such an increase deserve further study. QP<FCmt8  
Competing interests 1::LN(`<  
The author(s) declare that they have no competing interests. ~RCg.&[ou  
Authors' contributions 7>KQRLw  
AGT graded the photographs, performed literature search +|M{I= 8  
and wrote the first draft of the manuscript. JJW graded the $BaK'7=3*  
photographs, critically reviewed and modified the manuscript. m/KjJ"s,  
ER performed the statistical analysis and critically fxOE]d8v  
reviewed the manuscript. PM designed and directed the \E~Q1eAJT  
study, adjudicated cataract cases and critically reviewed `TkbF9N+  
and modified the manuscript. All authors read and p^Agh  
approved the final manuscript. M!-q}5';  
Acknowledgements m.Twgin  
This study was supported by the Australian National Health & Medical 4xpj<  
Research Council, Canberra, Australia (Grant Nos 974159, 991407). The H[Cj7{V  
abstract was presented at the Association for Research in Vision and Ophthalmology nc - Qz  
(ARVO) meeting in Fort Lauderdale, Florida, USA, May 2005. {dDq*s Lf  
References %5`r- F  
1. Congdon N, O'Colmain B, Klaver CC, Klein R, Munoz B, Friedman >b3@>W  
DS, Kempen J, Taylor HR, Mitchell P: Causes and prevalence of 1"M"h_4  
visual impairment among adults in the United States. Arch \A ;^ UxG  
Ophthalmol 2004, 122(4):477-485. ZHb7+  
2. Rahmani B, Tielsch JM, Katz J, Gottsch J, Quigley H, Javitt J, Sommer 7Onk!NH  
A: The cause-specific prevalence of visual impairment in an q$3HvZP  
urban population. The Baltimore Eye Survey. Ophthalmology X1O65DMr`g  
1996, 103:1721-1726. Q})t<l+L  
3. Keeffe JE, Konyama K, Taylor HR: Vision impairment in the " S ?Km  
Pacific region. Br J Ophthalmol 2002, 86:605-610. JXlTN[O  
4. Reidy A, Minassian DC, Vafidis G, Joseph J, Farrow S, Wu J, Desai P, rA[nUJ,  
Connolly A: Prevalence of serious eye disease and visual D\n>*x  
impairment in a north London population: population based, ;g&7*1E  
cross sectional study. BMJ 1998, 316:1643-1646. LH bZjZ2  
5. Resnikoff S, Pascolini D, Etya'ale D, Kocur I, Pararajasegaram R, :fl*w""V@  
Pokharel GP, Mariotti SP: Global data on visual impairment in }R4(B2vup  
the year 2002. Bull World Health Organ 2004, 82:844-851. vM5k4%D  
6. Pascolini D, Mariotti SP, Pokharel GP, Pararajasegaram R, Etya'ale D, 5%EaX?0h+  
Negrel AD, Resnikoff S: 2002 global update of available data on Hf;RIl2F  
visual impairment: a compilation of population-based prevalence (MZ A  
studies. Ophthalmic Epidemiol 2004, 11:67-115. [O.LUR;  
7. Rochtchina E, Mukesh BN, Wang JJ, McCarty CA, Taylor HR, Mitchell GH [ U!J  
P: Projected prevalence of age-related cataract and cataract |G[{{qZM5  
surgery in Australia for the years 2001 and 2021: pooled data .WxFm@]/\  
from two population-based surveys. Clin Experiment Ophthalmol >l y&+3S  
2003, 31:233-236. _HSTiJVr  
8. Medicare Benefits Schedule Statistics [http://www.medicar &z7N\n  
eaustralia.gov.au/statistics/dyn_mbs/forms/mbs_tab4.shtml] 9OE_?R0c!  
9. Keeffe JE, Taylor HR: Cataract surgery in Australia 1985–94. r0rJ.}!  
Aust N Z J Ophthalmol 1996, 24:313-317. x0}<n99qE  
10. Tan AG, Wang JJ, Rochtchina E, Jakobsen K, Mitchell P: Increase in Tb>IHoil  
cataract surgery prevalence from 1992–1994 to 1997–2000: R^n* o  
Analysis of two population cross-sections. Clin Experiment Ophthalmol gEcnn .(S  
2004, 32:284-288. -`<6=[QUO  
11. Mitchell P, Smith W, Attebo K, Wang JJ: Prevalence of age-related -MVNXAKnZ  
maculopathy in Australia. The Blue Mountains Eye Study. ^EnNbFI  
Ophthalmology 1995, 102:1450-1460. S jC)6mo  
12. Mitchell P, Cumming RG, Attebo K, Panchapakesan J: Prevalence of wz*)L (pP  
cataract in Australia: the Blue Mountains eye study. Ophthalmology +z~ !#j4Q  
1997, 104:581-588. @g@ fL%  
13. Klein BEK, Magli YL, Neider MW, Klein R: Wisconsin system for classification \i &vOH'  
of cataracts from photographs (protocol) Madison, WI; 1990. 7]<F>97  
14. Foran S, Wang JJ, Mitchell P: Causes of visual impairment in two =R"Eb1  
older population cross-sections: the Blue Mountains Eye b |o`Q7Hj  
Study. Ophthalmic Epidemiol 2003, 10:215-225. iA1;k*) q  
15. Congdon N, Vingerling JR, Klein BE, West S, Friedman DS, Kempen J, Mp DdJ,  
O'Colmain B, Wu SY, Taylor HR: Prevalence of cataract and 5bGjO&$l  
pseudophakia/aphakia among adults in the United States. yhJA;&}>  
Arch Ophthalmol 2004, 122:487-494. 0|K/=dh5+  
16. Sperduto RD, Hiller R: The prevalence of nuclear, cortical, and .O @q5G  
posterior subcapsular lens opacities in a general population O?4vC5x  
sample. Ophthalmology 1984, 91:815-818. O9Jx%tolF%  
17. Adamsons I, Munoz B, Enger C, Taylor HR: Prevalence of lens x):k#cu[L  
opacities in surgical and general populations. Arch Ophthalmol Bsih<`KF^  
1991, 109:993-997. =0!\F~  
18. Klein BE, Klein R, Linton KL: Prevalence of age-related lens {8*d;[X50  
opacities in a population. The Beaver Dam Eye Study. Ophthalmology `K@df<}%*,  
1992, 99:546-552. e!2%ku  
19. West SK, Munoz B, Schein OD, Duncan DD, Rubin GS: Racial differences g~$GE},,  
in lens opacities: the Salisbury Eye Evaluation (SEE) Ok~W@sYST  
project. Am J Epidemiol 1998, 148:1033-1039. b[&, %Sm+6  
20. Congdon N, West SK, Buhrmann RR, Kouzis A, Munoz B, Mkocha H: &ttv4BC^r  
Prevalence of the different types of age-related cataract in [Q.4]K2  
an African population. Invest Ophthalmol Vis Sci 2001, Te U7W?M^  
42:2478-2482. 8KL_PwRX_f  
21. Livingston PM, Guest CS, Stanislavsky Y, Lee S, Bayley S, Walker C, 7gdU9c/q,  
McKean C, Taylor HR: A population-based estimate of cataract &xiDG=I#  
prevalence: the Melbourne Visual Impairment Project experience. -'p@ lk  
Dev Ophthalmol 1994, 26:1-6. r PRuSk-f  
22. Leske MC, Connell AM, Wu SY, Hyman L, Schachat A: Prevalence tci%=3,)  
of lens opacities in the Barbados Eye Study. Arch Ophthalmol &T|&D[@  
1997, 115:105-111. published erratum appears in Arch Ophthalmol 5{d9,$%8&  
1997 Jul;115(7):931 U<,Kw6K  
23. Seah SK, Wong TY, Foster PJ, Ng TP, Johnson GJ: Prevalence of ~&j`9jdOj  
lens opacity in Chinese residents of Singapore: the tanjong G=bP<XF  
pagar survey. Ophthalmology 2002, 109:2058-2064. pJ*#aH[ySP  
24. Stifter E, Sacu S, Weghaupt H, Konig F, Richter-Muksch S, Thaler A, {i%x s#0h  
Velikay-Parel M, Radner W: Reading performance depending on F#}1{$)% /  
the type of cataract and its predictability on the visual outcome. mP$G 9R  
J Cataract Refract Surg 2004, 30:1259-1267. Vw;ldEdx  
25. Stifter E, Sacu S, Weghaupt H: Functional vision with cataracts of : ! iPn%  
different morphologies: comparative study. J Cataract Refract `d|bH; w  
Surg 2004, 30:1883-1891. FskJyB [  
26. Leske MC, Chylack LT Jr, Wu SY: The Lens Opacities Case-Control 1-N X>E5  
Study. Risk factors for cataract. Arch Ophthalmol 1991, 1={Tcq\]  
109:244-251. 9M7(_E;)B  
27. Leske MC, Wu SY, Hyman L, Sperduto R, Underwood B, Chylack LT, $Z%aGc*  
Milton RC, Srivastava S, Ansari N: Biochemical factors in the lens ]20 "la5  
opacities. Case-control study. The Lens Opacities Case-Control k@";i4}A  
Study Group. Arch Ophthalmol 1995, 113:1113-1119. ^3)2]>pW  
28. Yip R, Johnson C, Dallman PR: Age-related changes in laboratory , w'$T)  
values used in the diagnosis of anemia and iron deficiency. if!`Qid  
Am J Clin Nutr 1984, 39:427-436. n\"LN3  
29. Mitchell P, Smith W, Wang JJ, Cumming RG, Leeder SR, Burnett L: E#2k|TpH4  
Diabetes in an older Australian population. Diabetes Res Clin =E~5&W7  
Pract 1998, 41:177-184. eeJt4DV8v  
Pre-publication history h. (;GJO  
The pre-publication history for this paper can be accessed ^.1VhTB  
here: nC!^,c  
Publish with BioMed Central and every 6L> "m0  
scientist can read your work free of charge !4,xQ ^   
"BioMed Central will be the most significant development for +j: Ld(  
disseminating the results of biomedical research in our lifetime." )>M@hIV5>  
Sir Paul Nurse, Cancer Research UK (DMnwqr  
Your research papers will be: AW&s-b%P  
available free of charge to the entire biomedical community 4Z~D xo  
peer reviewed and published immediately upon acceptance 5F sj_wFk  
cited in PubMed and archived on PubMed Central Nl<,rD+KSD  
yours — you keep the copyright e, 0I~:  
Submit your manuscript here: F4< 2.V)#-  
http://www.biomedcentral.com/info/publishing_adv.asp XhD fI &  
BioMedcentral  wY_-  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 g7z9i[  
Page 7 of 7  <IDzv'  
(page number not for citation purposes) |j}F$*SE[  
http://www.biomedcentral.com/1471-2415/6/17/prepub
评价一下你浏览此帖子的感受

精彩

感动

搞笑

开心

愤怒

无聊

灌水

  
描述
快速回复

验证问题:
免费考博网网址是什么? 正确答案:freekaobo.com
按"Ctrl+Enter"直接提交