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 WCixKYq  
Page 1 of 7 ge8ZsaiU  
(page number not for citation purposes) {&1/ V  
BMC Ophthalmology u.xnOcOH!  
Research article Open Access Z"fJ`--  
Comparison of age-specific cataract prevalence in two ^Xh^xL2cn  
population-based surveys 6 years apart C1 *v,i  
Ava Grace Tan†, Jie Jin Wang*†, Elena Rochtchina† and Paul Mitchell† 1/J=uH  
Address: Centre for Vision Research, Westmead Millennium Institute, Department of Ophthalmology, University of Sydney, Westmead Hospital, I9ep`X6Y  
Westmead, NSW, Australia Qq|57X)P*  
Email: Ava Grace Tan - ava_tan@wmi.usyd.edu.au; Jie Jin Wang* - jiejin_wang@wmi.usyd.edu.au; Oxd]y1  
Elena Rochtchina - elena_rochtchina@wmi.usyd.edu.au; Paul Mitchell - paul_mitchell@wmi.usyd.edu.au -6B4sZpzD  
* Corresponding author †Equal contributors 7J<5f)  
Abstract P\k# >}}  
Background: In this study, we aimed to compare age-specific cortical, nuclear and posterior oYH-wQj  
subcapsular (PSC) cataract prevalence in two surveys 6 years apart. DN:EB @  
Methods: The Blue Mountains Eye Study examined 3654 participants (82.4% of those eligible) in XZd,&YiaG  
cross-section I (1992–4) and 3509 participants (75.1% of survivors and 85.2% of newly eligible) in ?.BC#S)q1  
cross-section II (1997–2000, 66.5% overlap with cross-section I). Cataract was assessed from lens oXF.1f/h  
photographs following the Wisconsin Cataract Grading System. Cortical cataract was defined if }&D32\  
cortical opacity comprised ≥ 5% of lens area. Nuclear cataract was defined if nuclear opacity ≥ A~70  
Wisconsin standard 4. PSC was defined if any present. Any cataract was defined to include persons h~zT ydnH  
who had previous cataract surgery. Weighted kappa for inter-grader reliability was 0.82, 0.55 and -(H0>Ap  
0.82 for cortical, nuclear and PSC cataract, respectively. We assessed age-specific prevalence using g`QEu 5v  
an interval of 5 years, so that participants within each age group were independent between the TuaBm1S{f  
two surveys. EXqE~afm2  
Results: Age and gender distributions were similar between the two populations. The age-specific e$rZ5X  
prevalence of cortical (23.8% in 1st, 23.7% in 2nd) and PSC cataract (6.3%, 6.0%) was similar. The t"oeQ*d%  
prevalence of nuclear cataract increased slightly from 18.7% to 23.9%. After age standardization, &{t,'[ u  
the similar prevalence of cortical (23.8%, 23.5%) and PSC cataract (6.3%, 5.9%), and the increased L.JT[zOfb  
prevalence of nuclear cataract (18.7%, 24.2%) remained. =@~Y12o?%  
Conclusion: In two surveys of two population-based samples with similar age and gender ' S/gmn  
distributions, we found a relatively stable cortical and PSC cataract prevalence over a 6-year period. X# ^[<5  
The increased prevalence of nuclear cataract deserves further study. 4BpZJ~(p  
Background @f3E`8  
Age-related cataract is the leading cause of reversible visual eTcd"Kd/  
impairment in older persons [1-6]. In Australia, it is 4{|"7/PE1  
estimated that by the year 2021, the number of people Ml-6 OvQ7g  
affected by cataract will increase by 63%, due to population X 0+vXz{~g  
aging [7]. Surgical intervention is an effective treatment DkDmE  
for cataract and normal vision (> 20/40) can usually BnF^u5kv%  
be restored with intraocular lens (IOL) implantation. +9sQZB# (  
Cataract surgery with IOL implantation is currently the >Cq<@$I2EB  
most commonly performed, and is, arguably, the most 5*u+q2\F  
cost effective surgical procedure worldwide. Performance E|shs=I  
Published: 20 April 2006 ) ;Y;Q  
BMC Ophthalmology 2006, 6:17 doi:10.1186/1471-2415-6-17 Dk51z@  
Received: 14 December 2005 >Y@H4LF;1x  
Accepted: 20 April 2006 {(Es(Sb}c  
This article is available from: http://www.biomedcentral.com/1471-2415/6/17 ~WF\  
© 2006 Tan et al; licensee BioMed Central Ltd. $U-0)4yf  
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), Z*6IW7#  
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. &m;*<}X  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 42ge3>  
Page 2 of 7 -M#Wt`6A  
(page number not for citation purposes) p!AAFmc  
of this surgical procedure has been continuously increasing sU^1wB Rj  
in the last two decades. Data from the Australian a(ZcmYzXU  
Health Insurance Commission has shown a steady @BMx!r5kn  
increase in Medicare claims for cataract surgery [8]. A 2.6- \cM2k-  
fold increase in the total number of cataract procedures lPAQ3t!,  
from 1985 to 1994 has been documented in Australia [9]. E2+`4g@{8<  
The rate of cataract surgery per thousand persons aged 65 &mM0AA'\?H  
years or older has doubled in the last 20 years [8,9]. In the W[r>.7>?h  
Blue Mountains Eye Study population, we observed a onethird W\V.r$? v  
increase in cataract surgery prevalence over a mean $<[79al#  
6-year interval, from 6% to nearly 8% in two cross-sectional *lJxH8\  
population-based samples with a similar age range bpa?C  
[10]. Further increases in cataract surgery performance 'dc#F3  
would be expected as a result of improved surgical skills 7 _[L o4_  
and technique, together with extending cataract surgical 2MK-5 Kg  
benefits to a greater number of older people and an  /G`]=@~  
increased number of persons with surgery performed on Y}KNKO;  
both eyes. )=(kBWM  
Both the prevalence and incidence of age-related cataract bcz:q/f}@  
link directly to the demand for, and the outcome of, cataract -trkA'ewZ  
surgery and eye health care provision. This report 0<*<$U  
aimed to assess temporal changes in the prevalence of cortical ?Z}&EH  
and nuclear cataract and posterior subcapsular cataract \z)%$#I  
(PSC) in two cross-sectional population-based ?gXp*>Kg[  
surveys 6 years apart. X5w$4Kj&4l  
Methods asqV~ n  
The Blue Mountains Eye Study (BMES) is a populationbased ?\n > AC  
cohort study of common eye diseases and other V28M lP  
health outcomes. The study involved eligible permanent o}{5i Tg=  
residents aged 49 years and older, living in two postcode W} ofAkF  
areas in the Blue Mountains, west of Sydney, Australia. ?&uu[y  
Participants were identified through a census and were EiaW1Cs  
invited to participate. The study was approved at each dgP 3@`YS  
stage of the data collection by the Human Ethics Committees c[s4EUG  
of the University of Sydney and the Western Sydney $Y gue5{c  
Area Health Service and adhered to the recommendations - ! S_ryL  
of the Declaration of Helsinki. Written informed consent !TcJ)0   
was obtained from each participant. A/?7w   
Details of the methods used in this study have been 3r1*m  +  
described previously [11]. The baseline examinations 6E}qL8'5x  
(BMES cross-section I) were conducted during 1992– VG~Vs@c(  
1994 and included 3654 (82.4%) of 4433 eligible residents. @KUWxFak  
Follow-up examinations (BMES IIA) were conducted *n"{J(Jt`  
during 1997–1999, with 2335 (75.0% of BMES ll?X@S  
cross section I survivors) participating. A repeat census of t3^&; &[  
the same area was performed in 1999 and identified 1378 W!(LF7_!  
newly eligible residents who moved into the area or the 9o!Bzy+_  
eligible age group. During 1999–2000, 1174 (85.2%) of ] }X  
this group participated in an extension study (BMES IIB). AwF:Iu^3n  
BMES cross-section II thus includes BMES IIA (66.5%) L{Vqh0QD&  
and BMES IIB (33.5%) participants (n = 3509). /_ajaz%  
Similar procedures were used for all stages of data collection S0W||#Pr  
at both surveys. A questionnaire was administered UR5`ue ;  
including demographic, family and medical history. A J4U1t2@)9  
detailed eye examination included subjective refraction, pI<f) r  
slit-lamp (Topcon SL-7e camera, Topcon Optical Co, 1yY0dOoLG)  
Tokyo, Japan) and retroillumination (Neitz CT-R camera, [=`q>|;pOv  
Neitz Instrument Co, Tokyo, Japan) photography of the *DhiN  
lens. Grading of lens photographs in the BMES has been }SCM I4\  
previously described [12]. Briefly, masked grading was Wh{tZ~c  
performed on the lens photographs using the Wisconsin bi;1s'Y<D  
Cataract Grading System [13]. Cortical cataract and PSC Rbv;?'O$L  
were assessed from the retroillumination photographs by Z;)%%V%o  
estimating the percentage of the circular grid involved. he hFEyx  
Cortical cataract was defined when cortical opacity '@P^0+B!(.  
involved at least 5% of the total lens area. PSC was defined }\k"n{!"  
when opacity comprised at least 1% of the total lens area.  #:%/(j  
Slit-lamp photographs were used to assess nuclear cataract |#N&akC  
using the Wisconsin standard set of four lens photographs Pg7Yp2)Oli  
[13]. Nuclear cataract was defined when nuclear opacity &b& ,  
was at least as great as the standard 4 photograph. Any cataract , ++ `=o  
was defined to include persons who had previous II x#2r  
cataract surgery as well as those with any of three cataract ^K@C"j?M/  
types. Inter-grader reliability was high, with weighted -z(+//K:#  
kappa 0.82 for cortical cataract, 0.55 (simple kappa 0.75) \dQNLLg/  
for nuclear cataract and 0.82 for PSC grading. The intragrader K", N!koj  
reliability for nuclear cataract was assessed with k"w"hg&e  
simple kappa 0.83 for the senior grader who graded wLr_-vJ  
nuclear cataract at both surveys. All PSC cases were confirmed }RqK84K  
by an ophthalmologist (PM). bA->{OPkT  
In cross-section I, 219 persons (6.0%) had missing or {Y9q[D'g.  
ungradable Neitz photographs, leaving 3435 with photographs 6)Lk-D  
available for cortical cataract and PSC assessment, kMd.h[X~  
while 1153 (31.6%) had randomly missing or ungradable `PH{syz  
Topcon photographs due to a camera malfunction, leaving 12LL48bi  
2501 with photographs available for nuclear cataract E< fVZ,  
assessment. Comparison of characteristics between participants T nm.A?  
with and without Neitz or Topcon photographs in ~e@z;]CiY  
cross-section I showed no statistically significant differences "9e\c;a  
between the two groups, as reported previously  sLQ^F  
[12]. In cross-section II, 441 persons (12.5%) had missing ~$?ZK]YOrx  
or ungradable Neitz photographs, leaving 3068 for cortical I2 P@L?h  
cataract and PSC assessment, and 648 (18.5%) had C~iL3C b  
missing or ungradable Topcon photographs, leaving 2860 n6a`;0f[R  
for nuclear cataract assessment. E~oOKQ5W  
Data analysis was performed using the Statistical Analysis @I!0-OjL  
System (SAS, SAS Institute, Cary, NC, USA). Age-adjusted ~R92cH>L  
prevalence was calculated using direct standardization of )I.$=s  
the cross-section II population to the cross-section I population. .0]<k,JZZ  
We assessed age-specific prevalence using an }U"&8%PZr  
interval of 5 years, so that participants within each age WI-1)1t  
group were independent between the two cross-sectional #4 pB@_  
surveys. 'SF<_aS(  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 9mTJ|sN:e  
Page 3 of 7 W|63Ir67  
(page number not for citation purposes) @t_=Yl2;  
Results DN57p!z  
Characteristics of the two survey populations have been & FN.:_E  
previously compared [14] and showed that age and sex _>X+ZlpU:  
distributions were similar. Table 1 compares participant Y glmX"fLf  
characteristics between the two cross-sections. Cross-section Gu\q%'I  
II participants generally had higher rates of diabetes, ;@Y;g(bw:  
hypertension, myopia and more users of inhaled steroids. e h?zNu2=  
Cataract prevalence rates in cross-sections I and II are q9r[$%G  
shown in Figure 1. The overall prevalence of cortical cataract i6Emhji  
was 23.8% and 23.7% in cross-sections I and II, lchPpm9  
respectively (age-sex adjusted P = 0.81). Corresponding 6zuTQ^pz  
prevalence of PSC was 6.3% and 6.0% for the two crosssections D7Q$ R:6|  
(age-sex adjusted P = 0.60). There was an ]K,Tnyp  
increased prevalence of nuclear cataract, from 18.7% in aE$[5 2  
cross-section I to 23.9% in cross-section II over the 6-year %S^8c  
period (age-sex adjusted P < 0.001). Prevalence of any cataract K} X&AJ5A  
(including persons who had cataract surgery), however, @>Km_Ax  
was relatively stable (46.9% and 46.8% in crosssections h^(* Tv-!  
I and II, respectively). z/2//mM  
After age-standardization, these prevalence rates remained 3kp+<$  
stable for cortical cataract (23.8% and 23.5% in the two XrGglBIV  
surveys) and PSC (6.3% and 5.9%). The slightly increased Sp]0c[37R  
prevalence of nuclear cataract (from 18.7% to 24.2%) was [MM~H0=s  
not altered. 7CURhDdk  
Table 2 shows the age-specific prevalence rates for cortical e)? .r9pA;  
cataract, PSC and nuclear cataract in cross-sections I and ,Ae6/D$h/  
II. A similar trend of increasing cataract prevalence with wc^tgE  
increasing age was evident for all three types of cataract in 0)e\`Bv  
both surveys. Comparing the age-specific prevalence ~/iKh1 1  
between the two surveys, a reduction in PSC prevalence in 1FL~ndJs  
cross-section II was observed in the older age groups (≥ 75 >7T'OC  
years). In contrast, increased nuclear cataract prevalence fW1CFRHH  
in cross-section II was observed in the older age groups (≥ :zke %Yx  
70 years). Age-specific cortical cataract prevalence was relatively 0{p#j~ZhC  
consistent between the two surveys, except for a K+K#+RBK  
reduction in prevalence observed in the 80–84 age group &>W$6>@  
and an increasing prevalence in the older age groups (≥ 85 )e=D(qd  
years). ' ;FnIZ  
Similar gender differences in cataract prevalence were S3*`jF>q  
observed in both surveys (Table 3). Higher prevalence of vm7z,Ff N  
cortical and nuclear cataract in women than men was evident .K2qXw"S#  
but the difference was only significant for cortical ;LPfXpR  
cataract (age-adjusted odds ratio, OR, for women 1.3, CMG&7(MR  
95% confidence intervals, CI, 1.1–1.5 in cross-section I S8 wLmd>  
and OR 1.4, 95% CI 1.1–1.6 in cross-section II). In con- J~ zUp(>K  
Table 1: Participant characteristics. w3obIJm  
Characteristics Cross-section I Cross-section II v,{ :Ez(H  
n % n % bL+_j}{:N  
Age (mean) (66.2) (66.7) y@:h4u"3  
50–54 485 13.3 350 10.0 O1U=X:Zl  
55–59 534 14.6 580 16.5 u=?.}Pj  
60–64 638 17.5 600 17.1 tGh~!|P  
65–69 671 18.4 639 18.2 HI R~"It$  
70–74 538 14.7 572 16.3 WwBOM~/`2  
75–79 422 11.6 407 11.6 L:pYn_  
80–84 230 6.3 226 6.4  gmO!  
85–89 100 2.7 110 3.1 H z1%x  
90+ 36 1.0 24 0.7 rq/yD,I,  
Female 2072 56.7 1998 57.0 3G)#5 Lf<  
Ever Smokers 1784 51.2 1789 51.2 0w \zLU  
Use of inhaled steroids 370 10.94 478 13.8^ Pg0x/X{t  
History of: vv3 * j&I  
Diabetes 284 7.8 347 9.9^ 7$vYo _  
Hypertension 1669 46.0 1825 52.2^ :0j?oY~e  
Emmetropia* 1558 42.9 1478 42.2 ['X]R:3h  
Myopia* 442 12.2 495 14.1^ x=hiQ>BIO0  
Hyperopia* 1633 45.0 1532 43.7 I {S;L  
n = number of persons affected M=.n7RY-  
* best spherical equivalent refraction correction j ^j1  
^ P < 0.01 av}k)ZT_  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 SO|NaqWa  
Page 4 of 7 @Q ]=\N:  
(page number not for citation purposes) UqFO|r"M  
t E"\<s3  
rast, men had slightly higher PSC prevalence than women {7" Q\  
in both cross-sections but the difference was not significant rxgbV.tx  
(OR 1.1, 95% CI 0.8–1.4 for men in cross-section I 7u -p%eq2  
and OR 1.2, 95% 0.9–1.6 in cross-section II). (Ft+uuG  
Discussion o]J{{M'E  
Findings from two surveys of BMES cross-sectional populations jH5 k  
with similar age and gender distribution showed ?mwt~_s9  
that the prevalence of cortical cataract and PSC remained RVnjNy;O`  
stable, while the prevalence of nuclear cataract appeared 8\@m - E!{  
to have increased. Comparison of age-specific prevalence, UAkT*'cB  
with totally independent samples within each age group, sQ UM~HD\a  
confirmed the robustness of our findings from the two GfxZ'VIn  
survey samples. Although lens photographs taken from :KSV4>X[%a  
the two surveys were graded for nuclear cataract by the h0*!;Z7  
same graders, who documented a high inter- and intragrader 59LZv-l  
reliability, we cannot exclude the possibility that VZp5)-!\  
variations in photography, performed by different photographers, d\&U*=  
may have contributed to the observed difference }Sm(]y  
in nuclear cataract prevalence. However, the overall ?h ZAxR\  
Table 2: Age-specific prevalence of cataract types in cross sections I and II. ^]>O;iB?  
Cataract type Age (years) Cross-section I Cross-section II m4[;(1  
n % (95% CL)* n % (95% CL)* FZ{h?#2?  
Cortical 50–54 473 4.4 (2.6–6.3) 338 7.4 (4.6–10.2) j nkR}wAA  
55–59 522 9.2 (6.7–11.7) 542 9.0 (6.6–11.5) B?eCe}*f;B  
60–64 615 16.4 (13.5–19.4) 556 16.7 (13.6–19.8) !j8FIY'[  
65–69 653 26.2 (22.8–29.6) 581 23.6 (20.1–27.0) .Yamc#A-  
70–74 516 31.2 (27.2–35.2) 514 35.4 (31.3–39.6) ? (@ 7r_j  
75–79 366 40.2 (35.1–45.2) 332 39.8 (34.5–45.1) ~dyTVJ$  
80–84 194 58.8 (51.8–65.8) 163 42.9 (35.3–50.6) |0&IXOW"XF  
85–89 74 52.7 (41.1–64.4) 73 54.8 (43.1–66.5) paA(C|%{  
90+ 22 68.2 (47.0–89.3) 14 78.6 (54.0–103.2) _>o:R$ %}  
PSC 50–54 474 2.7 (1.3–4.2) 338 2.4 (0.7–4.0) +r�  
55–59 522 2.9 (1.4–4.3) 541 2.6 (1.3–3.9) <v"R.<  
60–64 616 4.6 (2.9–6.2) 548 5.7 (3.7–7.6) :tc@2/>!O  
65–69 655 6.3 (4.4–8.1) 573 4.5 (2.8–6.3) E'f{i:O "~  
70–74 517 6.8 (4.6–8.9) 505 9.7 (7.1–12.3) =eq[:K<6  
75–79 367 11.4 (8.2–14.7) 327 9.5 (6.3–12.7) %HhBt5w  
80–84 196 12.2 (7.6–16.9) 155 10.3 (5.5–15.2) G~]Uk*M q  
85–89 74 18.9 (9.8–28.1) 69 11.6 (3.9–19.4) [@_Jj3`4  
90+ 23 21.7 (3.5–40.0) 11 0.0 &Gc9VF]o  
Nuclear 50–54 323 1.6 (0.2–2.9) 331 0.9 (–0.2–1.9) P7ao5NP  
55–59 386 2.3 (0.8–3.8) 507 3.6 (1.9–5.2) Ky`qskvu  
60–64 453 5.3 (3.2–7.4) 501 11.6 (8.8–14.4) 1;* cq  
65–69 478 17.2 (13.8–20.1) 534 18.5 (15.2–21.9) av(6wht8  
70–74 392 27.6 (23.1–32.0) 453 36.0 (31.6–40.4) JB\UKZXw  
75–79 255 45.1 (39.0–51.3) 302 55.6 (50.0–61.3) pj8=wch  
80–84 146 54.1 (45.9–62.3) 147 73.5 (66.3–80.7) qfX6TV5J}!  
85–89 50 64.0 (50.2–77.8) 70 80.0 (70.4–89.6) Do9x XK  
90+ 18 72.2 (49.3–95.1) 15 73.3 (48.0–98.7) `T1  
n = number of persons l& [O  
* 95% Confidence Limits uIY#e<)}G  
Cataract FMioguunrtea i1n ps rEeyvea lSetnucdey in cross-sections I and II of the Blue a1+oj7  
Cataract prevalence in cross-sections I and II of the Blue *nd!)t  
Mountains Eye Study. 4a&RYx  
0 //B&k`u  
10 }YQX~="  
20 )Dm s  
30 ,.S~ Y  
40 z>xmRs   
50 K&u_R  
cortical PSC nuclear any `Uq#W+r,  
cataract 7lTC{7C57  
Cataract type sVQ|*0(J0r  
% #-rH1h3*q  
Cross-section I XoK:N$\}t  
Cross-section II _=>He=v/  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 _IMW {  
Page 5 of 7 +SzU  
(page number not for citation purposes) x%=si[P  
prevalence of any cataract (including cataract surgery) was '$Dn  
relatively stable over the 6-year period. ';k5?^T  
Although different population-based studies used different alJ)^OSIe  
grading systems to assess cataract [15], the overall E#34Wh2z  
prevalence of the three cataract types were similar across _{ue8kGt  
different study populations [12,16-23]. Most studies have E*& vy  
suggested that nuclear cataract is the most prevalent type Ng &% o  
of cataract, followed by cortical cataract [16-20]. Ours and F~ty!(c  
other studies reported that cortical cataract was the most &$BjV{,/zc  
prevalent type [12,21-23]. >dXGee>'M  
Our age-specific prevalence data show a reduction of >IafUy  
15.9% in cortical cataract prevalence for the 80–84 year W ~<^L\Lu  
age group, concordant with an increase in cataract surgery HdI8f!X'TG  
prevalence by 9% in those aged 80+ years observed in the ho{*Cjv  
same study population [10]. Although cortical cataract is wVXS%4|v  
thought to be the least likely cataract type leading to a cataract *tFHM &a  
surgery, this may not be the case in all older persons. H H)!_(SA  
A relatively stable cortical cataract and PSC prevalence m,28u3@r  
over the 6-year period is expected. We cannot offer a  'c&Ed  
definitive explanation for the increase in nuclear cataract ~G p [_ %K  
prevalence. A possible explanation could be that a moderate 0 JS?;fk  
level of nuclear cataract causes less visual disturbance OKZV{Gja  
than the other two types of cataract, thus for the oldest age D8Ic?:iX[  
groups, persons with nuclear cataract could have been less iXkF1r]i  
likely to have surgery unless it is very dense or co-existing mUC)gA/  
with cortical cataract or PSC. Previous studies have shown w(Ovr`o?9t  
that functional vision and reading performance were high  ~NgA  
in patients undergoing cataract surgery who had nuclear tFn)aa~L  
cataract only compared to those with mixed type of cataract ,pfG  
(nuclear and cortical) or PSC [24,25]. In addition, the R{4^t97wH{  
overall prevalence of any cataract (including cataract surgery) Po;W'7"Po`  
was similar in the two cross-sections, which appears P[-E@0h)-t  
to support our speculation that in the oldest age group, _ye |Y  
nuclear cataract may have been less likely to be operated @7c?xQVd$  
than the other two types of cataract. This could have /HEw-M9z  
resulted in an increased nuclear cataract prevalence (due .sW|Id )  
to less being operated), compensated by the decreased 2qNt,;DQ  
prevalence of cortical cataract and PSC (due to these being <}Vrl`?h  
more likely to be operated), leading to stable overall prevalence  dFc':|  
of any cataract. {?0lBfB"  
Possible selection bias arising from selective survival Jr4Ky<G_i  
among persons without cataract could have led to underestimation :kV#y  
of cataract prevalence in both surveys. We }&D WaO]J7  
assume that such an underestimation occurred equally in u Mv,zO5  
both surveys, and thus should not have influenced our J{<X 7uB  
assessment of temporal changes. S+6.ZZ9c  
Measurement error could also have partially contributed y<3-?}.aZ  
to the observed difference in nuclear cataract prevalence. est 9M*Fn  
Assessment of nuclear cataract from photographs is a aO[w/cGQ  
potentially subjective process that can be influenced by l&zilVVm  
variations in photography (light exposure, focus and the H41?/U,{  
slit-lamp angle when the photograph was taken) and MchA{p&Ol  
grading. Although we used the same Topcon slit-lamp A{zN | S[  
camera and the same two graders who graded photos n8[!pH~6  
from both surveys, we are still not able to exclude the possibility Y|qTyE%  
of a partial influence from photographic variation ?$pCsBDo  
on this result. Gz0]}]A  
A similar gender difference (women having a higher rate 7A7?GDW  
than men) in cortical cataract prevalence was observed in >'$Mp<  
both surveys. Our findings are in keeping with observations .Hm>i  
from the Beaver Dam Eye Study [18], the Barbados _f,C[C[e&  
Eye Study [22] and the Lens Opacities Case-Control S hWJ72c  
Group [26]. It has been suggested that the difference re<{ >  
could be related to hormonal factors [18,22]. A previous wlvgg  
study on biochemical factors and cataract showed that a ajT*/L!0_  
lower level of iron was associated with an increased risk of Om@;J%u/  
cortical cataract [27]. No interaction between sex and biochemical }<r)~{UV  
factors were detected and no gender difference B$K=\6o  
was assessed in this study [27]. The gender difference seen ?V=ZIGj  
in cortical cataract could be related to relatively low iron "sCRdx]_  
levels and low hemoglobin concentration usually seen in Qv-_ jZ  
women [28]. Diabetes is a known risk factor for cortical #!# l45p6  
Table 3: Gender distribution of cataract types in cross-sections I and II. * fxG?}YT  
Cataract type Gender Cross-section I Cross-section II T -2t.Xs  
n % (95% CL)* n % (95% CL)* CRE3icXbQ  
Cortical Male 1496 21.1 (19.0–23.1) 1328 20.4 (18.2–22.6) BU_nh+dF  
Female 1939 25.9 (23.9–27.8) 1785 26.2 (24.2–28.3) _{KG 4+5\X  
PSC Male 1500 6.5 (5.2–7.7) 1314 6.4 (5.1–7.7) cI*;k.KU  
Female 1944 6.2 (5.1–7.2) 1753 5.7 (4.6–6.7) Kc-W&?~y#1  
Nuclear Male 1106 17.6 (15.4–19.9) 1225 22.5 (20.1–24.8) eym4=k ~  
Female 1395 19.5 (17.4–21.6) 1635 25.0 (22.9–27.1) Gd=RyoJl  
n = number of persons ~0$&3a<n1  
* 95% Confidence Limits 6{b >p+U  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 NLqzi%s  
Page 6 of 7 CdQ!GS<'y  
(page number not for citation purposes) 3pKQ$\u  
cataract but in this particular population diabetes is more uXvtfc  
prevalent in men than women in all age groups [29]. Differential ZE}}W _  
exposures to cataract risk factors or different dietary ez$(c  
or lifestyle patterns between men and women may }7Q%6&IR  
also be related to these observations and warrant further y)@wjH{6  
study. y N-9[P8C  
Conclusion bH~dJFj/  
In summary, in two population-based surveys 6 years 02^rV*re  
apart, we have documented a relatively stable prevalence ~} ~4  
of cortical cataract and PSC over the period. The observed (ZlU^Gw#UB  
overall increased nuclear cataract prevalence by 5% over a Ewz!O`  
6-year period needs confirmation by future studies, and d'> x(Yi  
reasons for such an increase deserve further study. t uX|\X  
Competing interests BgT*icd8d  
The author(s) declare that they have no competing interests. !4!~L k=  
Authors' contributions DY*N|OnqJ  
AGT graded the photographs, performed literature search %C]>9."  
and wrote the first draft of the manuscript. JJW graded the 7 tp36TE  
photographs, critically reviewed and modified the manuscript. l]SX@zTb  
ER performed the statistical analysis and critically >\8+: oS^  
reviewed the manuscript. PM designed and directed the /dHF6yW  
study, adjudicated cataract cases and critically reviewed e3\T)x &=  
and modified the manuscript. All authors read and k5)om;.w  
approved the final manuscript. @4#vm@Yf_  
Acknowledgements  D%Z|  
This study was supported by the Australian National Health & Medical ,zc(t<|-y  
Research Council, Canberra, Australia (Grant Nos 974159, 991407). The `vV7c`K?  
abstract was presented at the Association for Research in Vision and Ophthalmology dRMx[7jVA  
(ARVO) meeting in Fort Lauderdale, Florida, USA, May 2005. pR_9NfV{  
References ~LC-[&$  
1. Congdon N, O'Colmain B, Klaver CC, Klein R, Munoz B, Friedman -\MG}5?!  
DS, Kempen J, Taylor HR, Mitchell P: Causes and prevalence of X>^fEQq"  
visual impairment among adults in the United States. Arch ^zr`;cJ+c  
Ophthalmol 2004, 122(4):477-485. pCG}Z Ka  
2. Rahmani B, Tielsch JM, Katz J, Gottsch J, Quigley H, Javitt J, Sommer UxBpdm%dvP  
A: The cause-specific prevalence of visual impairment in an Dp:BU|r  
urban population. The Baltimore Eye Survey. Ophthalmology S jj6q`  
1996, 103:1721-1726. Y-9I3?ar  
3. Keeffe JE, Konyama K, Taylor HR: Vision impairment in the (k P9hcV  
Pacific region. Br J Ophthalmol 2002, 86:605-610. /{2,zW  
4. Reidy A, Minassian DC, Vafidis G, Joseph J, Farrow S, Wu J, Desai P, a9Vi];  
Connolly A: Prevalence of serious eye disease and visual r_d! ikOT(  
impairment in a north London population: population based, ^rz_f{c]-  
cross sectional study. BMJ 1998, 316:1643-1646. /_.|E]  
5. Resnikoff S, Pascolini D, Etya'ale D, Kocur I, Pararajasegaram R, ,: ^u-b|  
Pokharel GP, Mariotti SP: Global data on visual impairment in =MWHJ'3-/  
the year 2002. Bull World Health Organ 2004, 82:844-851. b2*TgnRq  
6. Pascolini D, Mariotti SP, Pokharel GP, Pararajasegaram R, Etya'ale D, 6~+e mlD  
Negrel AD, Resnikoff S: 2002 global update of available data on UZ";a453r  
visual impairment: a compilation of population-based prevalence +ai< q>+  
studies. Ophthalmic Epidemiol 2004, 11:67-115. &3&HY:yF  
7. Rochtchina E, Mukesh BN, Wang JJ, McCarty CA, Taylor HR, Mitchell H*6W q  
P: Projected prevalence of age-related cataract and cataract _dU\JD  
surgery in Australia for the years 2001 and 2021: pooled data {G-kNU  
from two population-based surveys. Clin Experiment Ophthalmol s[N@0  
2003, 31:233-236. ,z6~?6m  
8. Medicare Benefits Schedule Statistics [http://www.medicar /@5YW"1  
eaustralia.gov.au/statistics/dyn_mbs/forms/mbs_tab4.shtml] )}v l\7=  
9. Keeffe JE, Taylor HR: Cataract surgery in Australia 1985–94. 2zpr~cB=  
Aust N Z J Ophthalmol 1996, 24:313-317. #E]59_  
10. Tan AG, Wang JJ, Rochtchina E, Jakobsen K, Mitchell P: Increase in *ui</+  
cataract surgery prevalence from 1992–1994 to 1997–2000: W l4%GB  
Analysis of two population cross-sections. Clin Experiment Ophthalmol =M-p/uB]  
2004, 32:284-288. s^SJY{  
11. Mitchell P, Smith W, Attebo K, Wang JJ: Prevalence of age-related kVL.PY\K  
maculopathy in Australia. The Blue Mountains Eye Study. ^Dx&|UwiZa  
Ophthalmology 1995, 102:1450-1460. QW"! (`K  
12. Mitchell P, Cumming RG, Attebo K, Panchapakesan J: Prevalence of 4P0}+  
cataract in Australia: the Blue Mountains eye study. Ophthalmology 2pAW9R#UV-  
1997, 104:581-588. PW4q~rc=:  
13. Klein BEK, Magli YL, Neider MW, Klein R: Wisconsin system for classification #;<Y[hR{P  
of cataracts from photographs (protocol) Madison, WI; 1990. hOeRd#AQK  
14. Foran S, Wang JJ, Mitchell P: Causes of visual impairment in two <v P=zk  
older population cross-sections: the Blue Mountains Eye t&p|Ynz?i  
Study. Ophthalmic Epidemiol 2003, 10:215-225. &wX]_:?  
15. Congdon N, Vingerling JR, Klein BE, West S, Friedman DS, Kempen J, ?4B`9<j8%  
O'Colmain B, Wu SY, Taylor HR: Prevalence of cataract and {b{s<@?  
pseudophakia/aphakia among adults in the United States. y)*RV;^  
Arch Ophthalmol 2004, 122:487-494. \Cj B1] I  
16. Sperduto RD, Hiller R: The prevalence of nuclear, cortical, and `x|?&Ytmf9  
posterior subcapsular lens opacities in a general population (#'>(t(4  
sample. Ophthalmology 1984, 91:815-818. j#6.Gq  
17. Adamsons I, Munoz B, Enger C, Taylor HR: Prevalence of lens e;jdqF~v!  
opacities in surgical and general populations. Arch Ophthalmol Yw 9GN2AG  
1991, 109:993-997. T;uX4,|(  
18. Klein BE, Klein R, Linton KL: Prevalence of age-related lens +qoRP2  
opacities in a population. The Beaver Dam Eye Study. Ophthalmology 6wxs1G  
1992, 99:546-552. D]}G. v1  
19. West SK, Munoz B, Schein OD, Duncan DD, Rubin GS: Racial differences "oD[v  
in lens opacities: the Salisbury Eye Evaluation (SEE) :%.D78&  
project. Am J Epidemiol 1998, 148:1033-1039. O84i; S+-p  
20. Congdon N, West SK, Buhrmann RR, Kouzis A, Munoz B, Mkocha H: A's{j7  
Prevalence of the different types of age-related cataract in }*-@!wc-N  
an African population. Invest Ophthalmol Vis Sci 2001, o@Oqm>]SS  
42:2478-2482. rKn~qVls  
21. Livingston PM, Guest CS, Stanislavsky Y, Lee S, Bayley S, Walker C, :>*7=q=  
McKean C, Taylor HR: A population-based estimate of cataract w@b)g  
prevalence: the Melbourne Visual Impairment Project experience. OH88n69  
Dev Ophthalmol 1994, 26:1-6. N0lC0 N?_J  
22. Leske MC, Connell AM, Wu SY, Hyman L, Schachat A: Prevalence ,^:.dFH6  
of lens opacities in the Barbados Eye Study. Arch Ophthalmol i$@:@&(~Y  
1997, 115:105-111. published erratum appears in Arch Ophthalmol yLGRi^d#  
1997 Jul;115(7):931 *Uh!>Iv;  
23. Seah SK, Wong TY, Foster PJ, Ng TP, Johnson GJ: Prevalence of g*Phv|kI  
lens opacity in Chinese residents of Singapore: the tanjong y^k$Us  
pagar survey. Ophthalmology 2002, 109:2058-2064. Rv=YFo[B  
24. Stifter E, Sacu S, Weghaupt H, Konig F, Richter-Muksch S, Thaler A, \8 ":]EU  
Velikay-Parel M, Radner W: Reading performance depending on %$I;{-LD  
the type of cataract and its predictability on the visual outcome. IcEdG(  
J Cataract Refract Surg 2004, 30:1259-1267. y2v^-q3  
25. Stifter E, Sacu S, Weghaupt H: Functional vision with cataracts of [e q&C_|D  
different morphologies: comparative study. J Cataract Refract 5bIw?%dk(  
Surg 2004, 30:1883-1891. /{[o ~:'p  
26. Leske MC, Chylack LT Jr, Wu SY: The Lens Opacities Case-Control [Zrr)8A  
Study. Risk factors for cataract. Arch Ophthalmol 1991, @co S+t  
109:244-251. ?5p>BER?  
27. Leske MC, Wu SY, Hyman L, Sperduto R, Underwood B, Chylack LT, *I+Q~4  
Milton RC, Srivastava S, Ansari N: Biochemical factors in the lens ,I9bNO,%JK  
opacities. Case-control study. The Lens Opacities Case-Control lFk R=!?=  
Study Group. Arch Ophthalmol 1995, 113:1113-1119. CAlCDfKW}  
28. Yip R, Johnson C, Dallman PR: Age-related changes in laboratory vIvIfE  
values used in the diagnosis of anemia and iron deficiency. =%7 -ZH9  
Am J Clin Nutr 1984, 39:427-436. [KQi.u  
29. Mitchell P, Smith W, Wang JJ, Cumming RG, Leeder SR, Burnett L: 8(De^H lO  
Diabetes in an older Australian population. Diabetes Res Clin vX>)je5#  
Pract 1998, 41:177-184. uO**E-`  
Pre-publication history FwK] $4*  
The pre-publication history for this paper can be accessed rjP/l6 ~'  
here: y} '@R$  
Publish with BioMed Central and every DD Z@$L!  
scientist can read your work free of charge m'U0'}Ld};  
"BioMed Central will be the most significant development for GY*p?k<i  
disseminating the results of biomedical research in our lifetime." hoP]9&<T  
Sir Paul Nurse, Cancer Research UK _{>vTBU4F  
Your research papers will be: T|$H#n}  
available free of charge to the entire biomedical community mv><HqDL1  
peer reviewed and published immediately upon acceptance o-\[,}T)M  
cited in PubMed and archived on PubMed Central l{9Y  
yours — you keep the copyright x;S @bY  
Submit your manuscript here: =I<R!ZSN  
http://www.biomedcentral.com/info/publishing_adv.asp (:_$5&i7  
BioMedcentral NbobliC=  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 GyIV Hby  
Page 7 of 7 O1lNAcpeM  
(page number not for citation purposes) %>yL1BeA4  
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