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 G\~^&BAC  
Page 1 of 7 w~@[ r4W  
(page number not for citation purposes) G$=-,6kZO  
BMC Ophthalmology 7 .+al)hl  
Research article Open Access Ps>&"k$T  
Comparison of age-specific cataract prevalence in two L.)yXuo4  
population-based surveys 6 years apart km 5E)_]  
Ava Grace Tan†, Jie Jin Wang*†, Elena Rochtchina† and Paul Mitchell† .Q\\dESn"  
Address: Centre for Vision Research, Westmead Millennium Institute, Department of Ophthalmology, University of Sydney, Westmead Hospital, 8wFn}lw&  
Westmead, NSW, Australia w|Qd`  
Email: Ava Grace Tan - ava_tan@wmi.usyd.edu.au; Jie Jin Wang* - jiejin_wang@wmi.usyd.edu.au; ==9ZFdf  
Elena Rochtchina - elena_rochtchina@wmi.usyd.edu.au; Paul Mitchell - paul_mitchell@wmi.usyd.edu.au pXW`+<g0  
* Corresponding author †Equal contributors ;Bs^iL  
Abstract i21QJ6jPcI  
Background: In this study, we aimed to compare age-specific cortical, nuclear and posterior Yj8&  
subcapsular (PSC) cataract prevalence in two surveys 6 years apart. =cp;Q,t'9L  
Methods: The Blue Mountains Eye Study examined 3654 participants (82.4% of those eligible) in !J^tg2M8:  
cross-section I (1992–4) and 3509 participants (75.1% of survivors and 85.2% of newly eligible) in z8iENECwj  
cross-section II (1997–2000, 66.5% overlap with cross-section I). Cataract was assessed from lens 8/q*o>[?  
photographs following the Wisconsin Cataract Grading System. Cortical cataract was defined if *m&&1W_  
cortical opacity comprised ≥ 5% of lens area. Nuclear cataract was defined if nuclear opacity ≥ 0wvU?z%WK  
Wisconsin standard 4. PSC was defined if any present. Any cataract was defined to include persons e_.~n<=  
who had previous cataract surgery. Weighted kappa for inter-grader reliability was 0.82, 0.55 and :ICr\FY$  
0.82 for cortical, nuclear and PSC cataract, respectively. We assessed age-specific prevalence using @ ;J|xkJ  
an interval of 5 years, so that participants within each age group were independent between the k?-S`o%Q  
two surveys. gKQ@!U U8  
Results: Age and gender distributions were similar between the two populations. The age-specific 3- )kwy6L  
prevalence of cortical (23.8% in 1st, 23.7% in 2nd) and PSC cataract (6.3%, 6.0%) was similar. The { _X#fq0}  
prevalence of nuclear cataract increased slightly from 18.7% to 23.9%. After age standardization, "1%*'B^}bw  
the similar prevalence of cortical (23.8%, 23.5%) and PSC cataract (6.3%, 5.9%), and the increased rC rr "O#j  
prevalence of nuclear cataract (18.7%, 24.2%) remained. a71}y;W  
Conclusion: In two surveys of two population-based samples with similar age and gender Q9q9<J7j$  
distributions, we found a relatively stable cortical and PSC cataract prevalence over a 6-year period. k4mTZ}6E  
The increased prevalence of nuclear cataract deserves further study. /Mx CvEE  
Background Dauo(Uhuo  
Age-related cataract is the leading cause of reversible visual 05g?jV  
impairment in older persons [1-6]. In Australia, it is 9/H^t* 5t  
estimated that by the year 2021, the number of people P.1Qc)m4  
affected by cataract will increase by 63%, due to population a;yV#Y  
aging [7]. Surgical intervention is an effective treatment L]NYYP-  
for cataract and normal vision (> 20/40) can usually 0k7"H]J  
be restored with intraocular lens (IOL) implantation. {5.?'vMp  
Cataract surgery with IOL implantation is currently the i59k"pNm  
most commonly performed, and is, arguably, the most T/ Ez*iQW  
cost effective surgical procedure worldwide. Performance 2}@*Ki7  
Published: 20 April 2006 -%N}A3m!5  
BMC Ophthalmology 2006, 6:17 doi:10.1186/1471-2415-6-17 MIJ%_=sm4:  
Received: 14 December 2005 5I_hh?N4Z  
Accepted: 20 April 2006 %rX\ P  
This article is available from: http://www.biomedcentral.com/1471-2415/6/17 Q.uR<C6)v  
© 2006 Tan et al; licensee BioMed Central Ltd. /$<JCNGv  
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), '> 4+WZ1w5  
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.  bsD'\  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 Q0_M-^~WT  
Page 2 of 7 = c/3^e  
(page number not for citation purposes) dUUPhk0  
of this surgical procedure has been continuously increasing .Wd.) ^?  
in the last two decades. Data from the Australian EgCp:L{  
Health Insurance Commission has shown a steady zww?  
increase in Medicare claims for cataract surgery [8]. A 2.6- ,2E`:#$  
fold increase in the total number of cataract procedures t>m8iS>  
from 1985 to 1994 has been documented in Australia [9]. ~7KynE  
The rate of cataract surgery per thousand persons aged 65 \>w@=bq26  
years or older has doubled in the last 20 years [8,9]. In the zS,%msT^A  
Blue Mountains Eye Study population, we observed a onethird ]i9H_K  
increase in cataract surgery prevalence over a mean }D8~^   
6-year interval, from 6% to nearly 8% in two cross-sectional Ma n^\gkCi  
population-based samples with a similar age range $#g#[ /  
[10]. Further increases in cataract surgery performance ".Tf< F  
would be expected as a result of improved surgical skills N8u_=b{X  
and technique, together with extending cataract surgical l; "ub^AH  
benefits to a greater number of older people and an uKaf{=*  
increased number of persons with surgery performed on =k[(rvU3  
both eyes. n-L]YrDPK[  
Both the prevalence and incidence of age-related cataract Qu,)wfp~  
link directly to the demand for, and the outcome of, cataract ft*G*.0kO  
surgery and eye health care provision. This report sPZV>Q:zY  
aimed to assess temporal changes in the prevalence of cortical h7Shl<f  
and nuclear cataract and posterior subcapsular cataract NzwGc+\7}  
(PSC) in two cross-sectional population-based ?eY chVq  
surveys 6 years apart. +c~O0U1  
Methods {VrAh* #h  
The Blue Mountains Eye Study (BMES) is a populationbased =1uj1.h  
cohort study of common eye diseases and other [57V8%  
health outcomes. The study involved eligible permanent )%nt61P\W  
residents aged 49 years and older, living in two postcode reD[j,i&t.  
areas in the Blue Mountains, west of Sydney, Australia. 3XYIbXnk  
Participants were identified through a census and were mt&JgA/  
invited to participate. The study was approved at each $bM#\2'  
stage of the data collection by the Human Ethics Committees eO"\UDBV  
of the University of Sydney and the Western Sydney ZJ{+_ax0K  
Area Health Service and adhered to the recommendations UJyiRP:#]>  
of the Declaration of Helsinki. Written informed consent "O"^\f  
was obtained from each participant. }I'>r(K  
Details of the methods used in this study have been S^sW.(I  
described previously [11]. The baseline examinations  joSr,'x  
(BMES cross-section I) were conducted during 1992– gIf+.^/m1  
1994 and included 3654 (82.4%) of 4433 eligible residents. wft:eQ  
Follow-up examinations (BMES IIA) were conducted lk *QV  
during 1997–1999, with 2335 (75.0% of BMES 30T:* I|  
cross section I survivors) participating. A repeat census of D9pxe qf+=  
the same area was performed in 1999 and identified 1378 @bVh?T0~F,  
newly eligible residents who moved into the area or the CI3_lWax%  
eligible age group. During 1999–2000, 1174 (85.2%) of 5qAE9G!c  
this group participated in an extension study (BMES IIB). crOtQ  
BMES cross-section II thus includes BMES IIA (66.5%) ]nr BmKB  
and BMES IIB (33.5%) participants (n = 3509). Am}PXj6  
Similar procedures were used for all stages of data collection 2 ShlYW@~  
at both surveys. A questionnaire was administered <45dy5!Tz  
including demographic, family and medical history. A C&#KdvN/r  
detailed eye examination included subjective refraction, W$ d{  
slit-lamp (Topcon SL-7e camera, Topcon Optical Co, ;@;ie8H  
Tokyo, Japan) and retroillumination (Neitz CT-R camera, 07WIa@Q  
Neitz Instrument Co, Tokyo, Japan) photography of the ~.y4 ,-  
lens. Grading of lens photographs in the BMES has been JqV<A3i  
previously described [12]. Briefly, masked grading was yl;$#aZB  
performed on the lens photographs using the Wisconsin sOtNd({  
Cataract Grading System [13]. Cortical cataract and PSC A.cZa  
were assessed from the retroillumination photographs by p]IhQnj2  
estimating the percentage of the circular grid involved. ^Y*.Ktp,o  
Cortical cataract was defined when cortical opacity b}{9 :n/SC  
involved at least 5% of the total lens area. PSC was defined u$`x]K=Zsm  
when opacity comprised at least 1% of the total lens area. j*lWi0Z-  
Slit-lamp photographs were used to assess nuclear cataract dCJR,},\f  
using the Wisconsin standard set of four lens photographs  C(Gb  
[13]. Nuclear cataract was defined when nuclear opacity yA) +-  
was at least as great as the standard 4 photograph. Any cataract j`-y"6)  
was defined to include persons who had previous IXk'?9  
cataract surgery as well as those with any of three cataract )RKhEm%Vr2  
types. Inter-grader reliability was high, with weighted HC, 0" W  
kappa 0.82 for cortical cataract, 0.55 (simple kappa 0.75) `U>b6 {K  
for nuclear cataract and 0.82 for PSC grading. The intragrader -bX.4+U  
reliability for nuclear cataract was assessed with oUS>p":  
simple kappa 0.83 for the senior grader who graded K`83C`w.  
nuclear cataract at both surveys. All PSC cases were confirmed &ZFAUE ,[  
by an ophthalmologist (PM). ;,hoX6D$  
In cross-section I, 219 persons (6.0%) had missing or (ZR"O8  
ungradable Neitz photographs, leaving 3435 with photographs }^bL'  
available for cortical cataract and PSC assessment, L6}x3  
while 1153 (31.6%) had randomly missing or ungradable 5'[X&r %#  
Topcon photographs due to a camera malfunction, leaving &l*dYzqq  
2501 with photographs available for nuclear cataract <^Nj~+G'  
assessment. Comparison of characteristics between participants I%WK*AORM  
with and without Neitz or Topcon photographs in -L<Pm(v&  
cross-section I showed no statistically significant differences Xr;noV-X  
between the two groups, as reported previously UR=s{nFd  
[12]. In cross-section II, 441 persons (12.5%) had missing dNt|"9~&  
or ungradable Neitz photographs, leaving 3068 for cortical K:Go%3~,  
cataract and PSC assessment, and 648 (18.5%) had  0PbIWy'  
missing or ungradable Topcon photographs, leaving 2860 =KD*+.'\/  
for nuclear cataract assessment. zUu>kJZ  
Data analysis was performed using the Statistical Analysis ~n 9DG>a  
System (SAS, SAS Institute, Cary, NC, USA). Age-adjusted ',%&DA2  
prevalence was calculated using direct standardization of \Y 4Z Q"0Q  
the cross-section II population to the cross-section I population. ZEJa dR  
We assessed age-specific prevalence using an  n(1" 6  
interval of 5 years, so that participants within each age &3?yg61Ag  
group were independent between the two cross-sectional B.WkHY%/  
surveys. jYZWf `X~  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 .NC}TFN|  
Page 3 of 7 O{R5<"g  
(page number not for citation purposes) F'*&-l  
Results E e&$9 )t  
Characteristics of the two survey populations have been %%[TM(z  
previously compared [14] and showed that age and sex g7F Z -  
distributions were similar. Table 1 compares participant ijYLf.R<  
characteristics between the two cross-sections. Cross-section ^)pY2t<^  
II participants generally had higher rates of diabetes, s30_lddD  
hypertension, myopia and more users of inhaled steroids. Q(3x"+  
Cataract prevalence rates in cross-sections I and II are .D`#a  
shown in Figure 1. The overall prevalence of cortical cataract ^ I YN"yX_  
was 23.8% and 23.7% in cross-sections I and II, ?Sxnq#r#  
respectively (age-sex adjusted P = 0.81). Corresponding [\yI<^_a  
prevalence of PSC was 6.3% and 6.0% for the two crosssections e8 .bH#  
(age-sex adjusted P = 0.60). There was an 8msDJ {,X  
increased prevalence of nuclear cataract, from 18.7% in uBgHtjmae  
cross-section I to 23.9% in cross-section II over the 6-year 0%/(p?]M  
period (age-sex adjusted P < 0.001). Prevalence of any cataract STI3|}G*P  
(including persons who had cataract surgery), however, 3!L)7Z/  
was relatively stable (46.9% and 46.8% in crosssections 1<"kN^  
I and II, respectively). ;4IP7$3G  
After age-standardization, these prevalence rates remained CHB{P\WF  
stable for cortical cataract (23.8% and 23.5% in the two th)jEK;Z  
surveys) and PSC (6.3% and 5.9%). The slightly increased ;}qCIyuO]  
prevalence of nuclear cataract (from 18.7% to 24.2%) was ![V- e  
not altered. HApP*1J^c  
Table 2 shows the age-specific prevalence rates for cortical Me>'QVr  
cataract, PSC and nuclear cataract in cross-sections I and $;1~JOZh  
II. A similar trend of increasing cataract prevalence with hl+Yr)0\  
increasing age was evident for all three types of cataract in g:g>;" B O  
both surveys. Comparing the age-specific prevalence 49m/UeNZ  
between the two surveys, a reduction in PSC prevalence in F t}tIP7  
cross-section II was observed in the older age groups (≥ 75 wkGF&U  
years). In contrast, increased nuclear cataract prevalence Q8n?7JB  
in cross-section II was observed in the older age groups (≥ Fk4 3sqU6~  
70 years). Age-specific cortical cataract prevalence was relatively U# }.r<  
consistent between the two surveys, except for a {IVqV6:  
reduction in prevalence observed in the 80–84 age group )+G(4eIT  
and an increasing prevalence in the older age groups (≥ 85 Ub$$wOsf  
years). `6A"e Da  
Similar gender differences in cataract prevalence were dXj.e4,m  
observed in both surveys (Table 3). Higher prevalence of }bVyv H  
cortical and nuclear cataract in women than men was evident SUw{xGp  
but the difference was only significant for cortical TwN8|ibVmP  
cataract (age-adjusted odds ratio, OR, for women 1.3, SXL6)pX  
95% confidence intervals, CI, 1.1–1.5 in cross-section I +CkK4<dF  
and OR 1.4, 95% CI 1.1–1.6 in cross-section II). In con- ?9mY #_Of  
Table 1: Participant characteristics. -=RXhE_{  
Characteristics Cross-section I Cross-section II + |,CIl+  
n % n % (Gc5l MiX3  
Age (mean) (66.2) (66.7) }Z6/b _kV  
50–54 485 13.3 350 10.0 L,<.rr$:  
55–59 534 14.6 580 16.5 38#(ruv  
60–64 638 17.5 600 17.1 N%-nxbI\  
65–69 671 18.4 639 18.2 +[F8>9o&  
70–74 538 14.7 572 16.3 Q3D xjD  
75–79 422 11.6 407 11.6 h^ s}8y  
80–84 230 6.3 226 6.4 _i 8oWy1  
85–89 100 2.7 110 3.1 Rz)#VVYC=  
90+ 36 1.0 24 0.7 &ke4":7X  
Female 2072 56.7 1998 57.0 Ov9.qNT  
Ever Smokers 1784 51.2 1789 51.2 Ort\J~ O  
Use of inhaled steroids 370 10.94 478 13.8^ xQ[YQ!l  
History of: ^j` vk  
Diabetes 284 7.8 347 9.9^ qg O)@B+  
Hypertension 1669 46.0 1825 52.2^ -K0tK~%q  
Emmetropia* 1558 42.9 1478 42.2 wFvilF V  
Myopia* 442 12.2 495 14.1^ SXT/9FteZ  
Hyperopia* 1633 45.0 1532 43.7 6Z"%vrH  
n = number of persons affected bHP-Z9riv  
* best spherical equivalent refraction correction LOA 90.D  
^ P < 0.01 qgDBu\  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 H [v~  
Page 4 of 7 7+ysE  
(page number not for citation purposes) \yy!?Ul aI  
t NE! Xt<A  
rast, men had slightly higher PSC prevalence than women @iaN@`5I6s  
in both cross-sections but the difference was not significant }bHpFe  
(OR 1.1, 95% CI 0.8–1.4 for men in cross-section I 8(A:XQN"h  
and OR 1.2, 95% 0.9–1.6 in cross-section II). R%Z} J R.  
Discussion 9\xw}ph  
Findings from two surveys of BMES cross-sectional populations 1eJ\CdI  
with similar age and gender distribution showed /i"EVN`t  
that the prevalence of cortical cataract and PSC remained Y7p#K<y]9  
stable, while the prevalence of nuclear cataract appeared wD<G+Y}  
to have increased. Comparison of age-specific prevalence, 4 8DsRy  
with totally independent samples within each age group, 4qMHVPJv\  
confirmed the robustness of our findings from the two Vs"Z9p$U  
survey samples. Although lens photographs taken from v`fUAm/  
the two surveys were graded for nuclear cataract by the $?A]!Y;  
same graders, who documented a high inter- and intragrader LgaJp_d>9*  
reliability, we cannot exclude the possibility that qq/Cn4fN8  
variations in photography, performed by different photographers, &#;, P :.'  
may have contributed to the observed difference 4[#.N 3Y4*  
in nuclear cataract prevalence. However, the overall 3aOFpCs|#  
Table 2: Age-specific prevalence of cataract types in cross sections I and II. KIS.4nt#d"  
Cataract type Age (years) Cross-section I Cross-section II zqeU>V~<F  
n % (95% CL)* n % (95% CL)* P-mrH  
Cortical 50–54 473 4.4 (2.6–6.3) 338 7.4 (4.6–10.2) 4S=lO?\"A  
55–59 522 9.2 (6.7–11.7) 542 9.0 (6.6–11.5) kb6v2 ^8H  
60–64 615 16.4 (13.5–19.4) 556 16.7 (13.6–19.8) _ &M>f?l  
65–69 653 26.2 (22.8–29.6) 581 23.6 (20.1–27.0) Cu Gk?i  
70–74 516 31.2 (27.2–35.2) 514 35.4 (31.3–39.6) Grqs*V &|g  
75–79 366 40.2 (35.1–45.2) 332 39.8 (34.5–45.1) ?R+$4;iy  
80–84 194 58.8 (51.8–65.8) 163 42.9 (35.3–50.6) `Ctj]t  
85–89 74 52.7 (41.1–64.4) 73 54.8 (43.1–66.5) M{H&5 9v  
90+ 22 68.2 (47.0–89.3) 14 78.6 (54.0–103.2) Mc8^{br61  
PSC 50–54 474 2.7 (1.3–4.2) 338 2.4 (0.7–4.0) `MD/C Fl4  
55–59 522 2.9 (1.4–4.3) 541 2.6 (1.3–3.9) s6egd%r  
60–64 616 4.6 (2.9–6.2) 548 5.7 (3.7–7.6) [q@%)F  
65–69 655 6.3 (4.4–8.1) 573 4.5 (2.8–6.3)  l g C  
70–74 517 6.8 (4.6–8.9) 505 9.7 (7.1–12.3) |j+~Td3})&  
75–79 367 11.4 (8.2–14.7) 327 9.5 (6.3–12.7) M~6I-HexT|  
80–84 196 12.2 (7.6–16.9) 155 10.3 (5.5–15.2) usA!MMH4  
85–89 74 18.9 (9.8–28.1) 69 11.6 (3.9–19.4) pGFocw  
90+ 23 21.7 (3.5–40.0) 11 0.0 h(L5MZs  
Nuclear 50–54 323 1.6 (0.2–2.9) 331 0.9 (–0.2–1.9) 7Av]f3 Zr  
55–59 386 2.3 (0.8–3.8) 507 3.6 (1.9–5.2)  fwEi//1  
60–64 453 5.3 (3.2–7.4) 501 11.6 (8.8–14.4) ?,NAihN]  
65–69 478 17.2 (13.8–20.1) 534 18.5 (15.2–21.9) j{=%~  
70–74 392 27.6 (23.1–32.0) 453 36.0 (31.6–40.4) (}:xs,Ax  
75–79 255 45.1 (39.0–51.3) 302 55.6 (50.0–61.3) HL?pnT09  
80–84 146 54.1 (45.9–62.3) 147 73.5 (66.3–80.7) $d"+Njd  
85–89 50 64.0 (50.2–77.8) 70 80.0 (70.4–89.6) J3]m*i5A  
90+ 18 72.2 (49.3–95.1) 15 73.3 (48.0–98.7) !=we7vK}  
n = number of persons OK 6}9Eu9  
* 95% Confidence Limits { SfU!  
Cataract FMioguunrtea i1n ps rEeyvea lSetnucdey in cross-sections I and II of the Blue !xI![N^  
Cataract prevalence in cross-sections I and II of the Blue d1-p];&  
Mountains Eye Study. >MT)=4 9q  
0 H #BgE29  
10 #!/Nmd=Nj  
20 To`?<]8  
30 wu')Q/v  
40 5glGlD6R  
50 i`qh|w/b_  
cortical PSC nuclear any > =H8>X  
cataract GLyh1qNX  
Cataract type u i1m+  
% ks D1NB;9  
Cross-section I c &HoS  
Cross-section II LnGSYrx1  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 BP$#a #  
Page 5 of 7 =&b[V"  
(page number not for citation purposes) vEGK {rMA  
prevalence of any cataract (including cataract surgery) was Oe`t!&v  
relatively stable over the 6-year period. z7 C1&bGe  
Although different population-based studies used different U5"OhI  
grading systems to assess cataract [15], the overall V m.@qO*=  
prevalence of the three cataract types were similar across W<"\hQI  
different study populations [12,16-23]. Most studies have N/BU%c ph+  
suggested that nuclear cataract is the most prevalent type WKsx|a]U  
of cataract, followed by cortical cataract [16-20]. Ours and +ctv]'P_  
other studies reported that cortical cataract was the most sfE8b/Z8  
prevalent type [12,21-23]. Oy$BR <\  
Our age-specific prevalence data show a reduction of 8 -A7  
15.9% in cortical cataract prevalence for the 80–84 year QE2^.|d{  
age group, concordant with an increase in cataract surgery 0(x@ NGb>{  
prevalence by 9% in those aged 80+ years observed in the rrYp^xLa`  
same study population [10]. Although cortical cataract is B}+9U  
thought to be the least likely cataract type leading to a cataract ~-wJ#E3g  
surgery, this may not be the case in all older persons. %PbqASm  
A relatively stable cortical cataract and PSC prevalence F*VMS  
over the 6-year period is expected. We cannot offer a +z0}{,HX  
definitive explanation for the increase in nuclear cataract yMl'1W  
prevalence. A possible explanation could be that a moderate L]N2r MM  
level of nuclear cataract causes less visual disturbance =@=R)C4f*  
than the other two types of cataract, thus for the oldest age &\|<3sd(  
groups, persons with nuclear cataract could have been less <Cu?$  
likely to have surgery unless it is very dense or co-existing myOX:K*  
with cortical cataract or PSC. Previous studies have shown o~_>p/7;  
that functional vision and reading performance were high E(kpK5h{  
in patients undergoing cataract surgery who had nuclear cjC6\.+l3  
cataract only compared to those with mixed type of cataract g*?+ ~0"`Y  
(nuclear and cortical) or PSC [24,25]. In addition, the I S8nvx\  
overall prevalence of any cataract (including cataract surgery) ^.kAZSgO  
was similar in the two cross-sections, which appears 9$V_=Bo  
to support our speculation that in the oldest age group, 0gD59N'C  
nuclear cataract may have been less likely to be operated >ydb?  
than the other two types of cataract. This could have RG r'<o)  
resulted in an increased nuclear cataract prevalence (due 7h9[-d6  
to less being operated), compensated by the decreased e$+f~~K  
prevalence of cortical cataract and PSC (due to these being 6 Y_O^f  
more likely to be operated), leading to stable overall prevalence |;u%JW$4  
of any cataract. yX.5Y|A<  
Possible selection bias arising from selective survival (&S[R{=^j  
among persons without cataract could have led to underestimation 7M#$: Fdb  
of cataract prevalence in both surveys. We @W\4UX3dK  
assume that such an underestimation occurred equally in 1;:t~Y  
both surveys, and thus should not have influenced our `Ivw`}L  
assessment of temporal changes. Prb_/B Dd  
Measurement error could also have partially contributed #w,WwL!  
to the observed difference in nuclear cataract prevalence. ~? FrI  
Assessment of nuclear cataract from photographs is a ?+,*YVT  
potentially subjective process that can be influenced by 7hF,gl5  
variations in photography (light exposure, focus and the W^d4/]  
slit-lamp angle when the photograph was taken) and Q_]!an(  
grading. Although we used the same Topcon slit-lamp ,;cel^.b  
camera and the same two graders who graded photos F;Q_*0mIQ  
from both surveys, we are still not able to exclude the possibility *0&4mi8  
of a partial influence from photographic variation eN| HJ=  
on this result. {GQ Aa  
A similar gender difference (women having a higher rate #7~tL23}]  
than men) in cortical cataract prevalence was observed in \at-"[.  
both surveys. Our findings are in keeping with observations N(_ .N6  
from the Beaver Dam Eye Study [18], the Barbados ]D ?# \|  
Eye Study [22] and the Lens Opacities Case-Control BbXU| QtY  
Group [26]. It has been suggested that the difference ~X~xE]1o|U  
could be related to hormonal factors [18,22]. A previous xgtJl} L  
study on biochemical factors and cataract showed that a T\2) $  
lower level of iron was associated with an increased risk of qu<B%v  
cortical cataract [27]. No interaction between sex and biochemical d DIQ+/mmg  
factors were detected and no gender difference D%;wVnU w  
was assessed in this study [27]. The gender difference seen A#Q0{z@H  
in cortical cataract could be related to relatively low iron 462!;/ y  
levels and low hemoglobin concentration usually seen in VBbUl|X\  
women [28]. Diabetes is a known risk factor for cortical W>}Qer4  
Table 3: Gender distribution of cataract types in cross-sections I and II. Th7wP:iDP  
Cataract type Gender Cross-section I Cross-section II 8S.')<-f  
n % (95% CL)* n % (95% CL)* HUU >hq9  
Cortical Male 1496 21.1 (19.0–23.1) 1328 20.4 (18.2–22.6) P[rAJJN/E  
Female 1939 25.9 (23.9–27.8) 1785 26.2 (24.2–28.3) q)K-vt)98  
PSC Male 1500 6.5 (5.2–7.7) 1314 6.4 (5.1–7.7) `d}W;&c  
Female 1944 6.2 (5.1–7.2) 1753 5.7 (4.6–6.7) 6P%<[Z  
Nuclear Male 1106 17.6 (15.4–19.9) 1225 22.5 (20.1–24.8) 'GV&]   
Female 1395 19.5 (17.4–21.6) 1635 25.0 (22.9–27.1) \#\`!L[1  
n = number of persons |`_ <@b  
* 95% Confidence Limits u;+%Qh  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 6?%]odI#  
Page 6 of 7 F-$Z,Q]S  
(page number not for citation purposes) lQh E]m>+  
cataract but in this particular population diabetes is more Jj=yG"$!  
prevalent in men than women in all age groups [29]. Differential 2UU 2Vm_6  
exposures to cataract risk factors or different dietary Hi]vHG(  
or lifestyle patterns between men and women may =gW"#ZjL){  
also be related to these observations and warrant further "2ZIoa!^  
study. ?JuX~{{. L  
Conclusion x9xz m5  
In summary, in two population-based surveys 6 years /\TQc-k?2  
apart, we have documented a relatively stable prevalence |f"-|6  
of cortical cataract and PSC over the period. The observed g/OI|1a  
overall increased nuclear cataract prevalence by 5% over a f|X[gL,B  
6-year period needs confirmation by future studies, and AU0$A403  
reasons for such an increase deserve further study. Ezi' 2Sc  
Competing interests @b]VCv0*f%  
The author(s) declare that they have no competing interests. q|n97.vD  
Authors' contributions 'GrRuT<  
AGT graded the photographs, performed literature search H!Wis3S3G  
and wrote the first draft of the manuscript. JJW graded the p:Iw%eZ:  
photographs, critically reviewed and modified the manuscript. :0B |<~lX  
ER performed the statistical analysis and critically 1T!cc%ah  
reviewed the manuscript. PM designed and directed the kVWGDI$~  
study, adjudicated cataract cases and critically reviewed nARxn#<+  
and modified the manuscript. All authors read and T48BRVX-F  
approved the final manuscript. {V.Wk  
Acknowledgements d "2wO[  
This study was supported by the Australian National Health & Medical +:}kZDl@ X  
Research Council, Canberra, Australia (Grant Nos 974159, 991407). The Dp^"J85}   
abstract was presented at the Association for Research in Vision and Ophthalmology {":c@I  
(ARVO) meeting in Fort Lauderdale, Florida, USA, May 2005. P%iP:16  
References M Z2^@It  
1. Congdon N, O'Colmain B, Klaver CC, Klein R, Munoz B, Friedman 2v4W6R  
DS, Kempen J, Taylor HR, Mitchell P: Causes and prevalence of l@xWQj9  
visual impairment among adults in the United States. Arch cbfD B^_  
Ophthalmol 2004, 122(4):477-485. v3 -5"q!Sq  
2. Rahmani B, Tielsch JM, Katz J, Gottsch J, Quigley H, Javitt J, Sommer &0s*P G  
A: The cause-specific prevalence of visual impairment in an H*GlWgfG  
urban population. The Baltimore Eye Survey. Ophthalmology f#1/}Hq/I  
1996, 103:1721-1726. ^1R"7h  
3. Keeffe JE, Konyama K, Taylor HR: Vision impairment in the $_wo6/J5+D  
Pacific region. Br J Ophthalmol 2002, 86:605-610. I,]J=xi  
4. Reidy A, Minassian DC, Vafidis G, Joseph J, Farrow S, Wu J, Desai P, -'j7SOGk  
Connolly A: Prevalence of serious eye disease and visual .wP/ai>}  
impairment in a north London population: population based, QPX`l0V  
cross sectional study. BMJ 1998, 316:1643-1646. oooS s&t  
5. Resnikoff S, Pascolini D, Etya'ale D, Kocur I, Pararajasegaram R, +^Fp&K+^  
Pokharel GP, Mariotti SP: Global data on visual impairment in ewpig4  
the year 2002. Bull World Health Organ 2004, 82:844-851. Vu%n&uF  
6. Pascolini D, Mariotti SP, Pokharel GP, Pararajasegaram R, Etya'ale D, z" EWj73  
Negrel AD, Resnikoff S: 2002 global update of available data on f\ ' T_  
visual impairment: a compilation of population-based prevalence f9a$$nb3`  
studies. Ophthalmic Epidemiol 2004, 11:67-115. |U EC  
7. Rochtchina E, Mukesh BN, Wang JJ, McCarty CA, Taylor HR, Mitchell v$;@0t:;#  
P: Projected prevalence of age-related cataract and cataract !j0_ cA  
surgery in Australia for the years 2001 and 2021: pooled data Y([d;_#P  
from two population-based surveys. Clin Experiment Ophthalmol `0rRKlbj4  
2003, 31:233-236. O>%$q8x@i  
8. Medicare Benefits Schedule Statistics [http://www.medicar 57<Di!rt  
eaustralia.gov.au/statistics/dyn_mbs/forms/mbs_tab4.shtml] \sITwPA[z  
9. Keeffe JE, Taylor HR: Cataract surgery in Australia 1985–94. IT18v[-G  
Aust N Z J Ophthalmol 1996, 24:313-317. ?2ItTrlB  
10. Tan AG, Wang JJ, Rochtchina E, Jakobsen K, Mitchell P: Increase in gHZqA_*T8U  
cataract surgery prevalence from 1992–1994 to 1997–2000: AuXs B  
Analysis of two population cross-sections. Clin Experiment Ophthalmol 0<Q*7aY  
2004, 32:284-288. x6v,lR  
11. Mitchell P, Smith W, Attebo K, Wang JJ: Prevalence of age-related P$OUi!"  
maculopathy in Australia. The Blue Mountains Eye Study. *gDl~qNRoS  
Ophthalmology 1995, 102:1450-1460. :BD>yOlG  
12. Mitchell P, Cumming RG, Attebo K, Panchapakesan J: Prevalence of -?z\5 z  
cataract in Australia: the Blue Mountains eye study. Ophthalmology @vt$MiOi  
1997, 104:581-588. j8a[ (  
13. Klein BEK, Magli YL, Neider MW, Klein R: Wisconsin system for classification Ha218Hy0W  
of cataracts from photographs (protocol) Madison, WI; 1990. #ouE r-=  
14. Foran S, Wang JJ, Mitchell P: Causes of visual impairment in two M)O [j}N  
older population cross-sections: the Blue Mountains Eye 1qZG`Vz  
Study. Ophthalmic Epidemiol 2003, 10:215-225. TF2KZL#A|  
15. Congdon N, Vingerling JR, Klein BE, West S, Friedman DS, Kempen J, 2M&$Wuu.q  
O'Colmain B, Wu SY, Taylor HR: Prevalence of cataract and \0&SI1Yp  
pseudophakia/aphakia among adults in the United States. y\,f6=%k  
Arch Ophthalmol 2004, 122:487-494. ,H{={aln  
16. Sperduto RD, Hiller R: The prevalence of nuclear, cortical, and 5\'AD^{  
posterior subcapsular lens opacities in a general population ] \dHU.i  
sample. Ophthalmology 1984, 91:815-818. gr+Pl>C{  
17. Adamsons I, Munoz B, Enger C, Taylor HR: Prevalence of lens FM\[].  
opacities in surgical and general populations. Arch Ophthalmol oY.\)eJ~>  
1991, 109:993-997. YlKFw|=  
18. Klein BE, Klein R, Linton KL: Prevalence of age-related lens hB>^'6h+  
opacities in a population. The Beaver Dam Eye Study. Ophthalmology P=gJAE5  
1992, 99:546-552. u"Y]P*[k  
19. West SK, Munoz B, Schein OD, Duncan DD, Rubin GS: Racial differences Hi8Y6|y$D  
in lens opacities: the Salisbury Eye Evaluation (SEE) $^h?:L:1n  
project. Am J Epidemiol 1998, 148:1033-1039. -N# #w=  
20. Congdon N, West SK, Buhrmann RR, Kouzis A, Munoz B, Mkocha H: 5@f5S0 Y  
Prevalence of the different types of age-related cataract in ?cK]C2Ak  
an African population. Invest Ophthalmol Vis Sci 2001, ,g|2NjUAc  
42:2478-2482. _ECB^s_  
21. Livingston PM, Guest CS, Stanislavsky Y, Lee S, Bayley S, Walker C, D#0O[F@l##  
McKean C, Taylor HR: A population-based estimate of cataract y6%<zhs  
prevalence: the Melbourne Visual Impairment Project experience. 5[R?iSGL1  
Dev Ophthalmol 1994, 26:1-6. j^ EbO3  
22. Leske MC, Connell AM, Wu SY, Hyman L, Schachat A: Prevalence U^?= 0+  
of lens opacities in the Barbados Eye Study. Arch Ophthalmol  uJ8{HB  
1997, 115:105-111. published erratum appears in Arch Ophthalmol 0>@[o8  
1997 Jul;115(7):931 fM ^<+o@  
23. Seah SK, Wong TY, Foster PJ, Ng TP, Johnson GJ: Prevalence of &t3Jv{  
lens opacity in Chinese residents of Singapore: the tanjong 3.),bm  
pagar survey. Ophthalmology 2002, 109:2058-2064. RL &lKHA  
24. Stifter E, Sacu S, Weghaupt H, Konig F, Richter-Muksch S, Thaler A, +)gB9DoK  
Velikay-Parel M, Radner W: Reading performance depending on HJ@5B"  
the type of cataract and its predictability on the visual outcome. >S.91!x  
J Cataract Refract Surg 2004, 30:1259-1267. a R)?a;}H  
25. Stifter E, Sacu S, Weghaupt H: Functional vision with cataracts of ug&92Hdvy3  
different morphologies: comparative study. J Cataract Refract zH=hI Vc  
Surg 2004, 30:1883-1891. }\Z5{OA  
26. Leske MC, Chylack LT Jr, Wu SY: The Lens Opacities Case-Control  yekRwo|  
Study. Risk factors for cataract. Arch Ophthalmol 1991, x)R0F\_  
109:244-251. :hP58 }Q$  
27. Leske MC, Wu SY, Hyman L, Sperduto R, Underwood B, Chylack LT, h8.FX-0& =  
Milton RC, Srivastava S, Ansari N: Biochemical factors in the lens x+^Vg3 q  
opacities. Case-control study. The Lens Opacities Case-Control $?f]ZyZr.  
Study Group. Arch Ophthalmol 1995, 113:1113-1119. =]b9X7}  
28. Yip R, Johnson C, Dallman PR: Age-related changes in laboratory hdg<bZk:  
values used in the diagnosis of anemia and iron deficiency. ,q</@}.\wN  
Am J Clin Nutr 1984, 39:427-436. ]^ 'ZiyJX  
29. Mitchell P, Smith W, Wang JJ, Cumming RG, Leeder SR, Burnett L: Vp7b4n<  
Diabetes in an older Australian population. Diabetes Res Clin |yv]Y/ =  
Pract 1998, 41:177-184. 7K:FeW'N  
Pre-publication history } 07r  
The pre-publication history for this paper can be accessed 0b++ 17aV  
here: P` ]ps?l  
Publish with BioMed Central and every jY+Do:#/wO  
scientist can read your work free of charge 5/(sjMB  
"BioMed Central will be the most significant development for Q>%E`h  
disseminating the results of biomedical research in our lifetime." tN!Bvj:C[M  
Sir Paul Nurse, Cancer Research UK /7vE>mSY  
Your research papers will be: PbN3;c3  
available free of charge to the entire biomedical community ^A#x<J+  
peer reviewed and published immediately upon acceptance GNZ#q)qT  
cited in PubMed and archived on PubMed Central m1y ` v"  
yours — you keep the copyright EL +,jrU~  
Submit your manuscript here: A]xCF{*)&  
http://www.biomedcentral.com/info/publishing_adv.asp xVTo4-[p  
BioMedcentral 8!4[#y<  
BMC Ophthalmology 2006, 6:17 http://www.biomedcentral.com/1471-2415/6/17 ArX]L$ D  
Page 7 of 7 'M-)Os "  
(page number not for citation purposes) g]4y AV<2  
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