ABSTRACT
= BW>jD Purpose: To quantify the prevalence of cataract, the outcomes
Bgs3sM9 of cataract surgery and the factors related to
AK%2#}k. unoperated cataract in Australia.
Kj;gxYD>6 Methods: Participants were recruited from the Visual
Ht#5;c2/ Impairment Project: a cluster, stratified sample of more than
v~i/e+.h>y 5000 Victorians aged 40 years and over. At examination
M; *f(JY$ sites interviews, clinical examinations and lens photography
v#i,pBj were performed. Cataract was defined in participants who
Ym
IVtQ had: had previous cataract surgery, cortical cataract greater
NFpR jC? than 4/16, nuclear greater than Wilmer standard 2, or
]&%_Fpx posterior subcapsular greater than 1 mm2.
1B+uv0lA Results: The participant group comprised 3271 Melbourne
3n-~+2l residents, 403 Melbourne nursing home residents and 1473
>-fOkOWXy rural residents.The weighted rate of any cataract in Victoria
Oi#F was 21.5%. The overall weighted rate of prior cataract
mEsOYIu{ surgery was 3.79%. Two hundred and forty-nine eyes had
m~a' had prior cataract surgery. Of these 249 procedures, 49
9A0wiKp (20%) were aphakic, 6 (2.4%) had anterior chamber
?u`+?"'H intraocular lenses and 194 (78%) had posterior chamber
ab4(?-'- intraocular lenses.Two hundred and eleven of these operated
J
WaI[n} eyes (85%) had best-corrected visual acuity of 6/12 or
,YzrqVY better, the legal requirement for a driver’s license.Twentyseven
)!2$yD (11%) had visual acuity of less than 6/18 (moderate
b
z3& vision impairment). Complications of cataract surgery
Bu4J8eLx caused reduced vision in four of the 27 eyes (15%), or 1.9%
y7J2:/@[x of operated eyes. Three of these four eyes had undergone
d%tF~|#A% intracapsular cataract extraction and the fourth eye had an
9Qja|;
opaque posterior capsule. No one had bilateral vision
RzG7Xr=t impairment as a result of cataract surgery. Surprisingly, no
#4uuT?! particular demographic factors (such as age, gender, rural
f4F13n_0X residence, occupation, employment status, health insurance
O/EI8Qvm status, ethnicity) were related to the presence of unoperated
?"oW1a\ cataract.
Y`$dtg { Conclusions: Although the overall prevalence of cataract is
H(}Jt!/: quite high, no particular subgroup is systematically underserviced
~zdHJ8tYp in terms of cataract surgery. Overall, the results of
b5r.N1ms cataract surgery are very good, with the majority of eyes
{Dv^j# achieving driving vision following cataract extraction.
p6=L}L
Key words: cataract extraction, health planning, health
uCX+Lw+As services accessibility, prevalence
pv/LTv INTRODUCTION
46U?aHKW@| Cataract is the leading cause of blindness worldwide and, in
){yw
k Australia, cataract extractions account for the majority of all
<zmtVE*>g ophthalmic procedures.1 Over the period 1985–94, the rate
]xJ5}/ of cataract surgery in Australia was twice as high as would be
6]`XW0{C expected from the growth in the elderly population.1
.m',*s<CMQ Although there have been a number of studies reporting
,:RHhg the prevalence of cataract in various populations,2–6 there is
H)#HK!F6f little information about determinants of cataract surgery in
A\{dq: the population. A previous survey of Australian ophthalmologists
2L=+z1%I showed that patient concern and lifestyle, rather
TRB)cJZ? than visual acuity itself, are the primary factors for referral
p8yn? ~]^ for cataract surgery.7 This supports prior research which has
:` FL95 shown that visual acuity is not a strong predictor of need for
&hciv\YT2W cataract surgery.8,9 Elsewhere, socioeconomic status has
N*d
)<8_ been shown to be related to cataract surgery rates.10
}B-@lbK6) To appropriately plan health care services, information is
\\<waU'' needed about the prevalence of age-related cataract in the
eh`s fH community as well as the factors associated with cataract
+kh#Jq. surgery. The purpose of this study is to quantify the prevalence
z:Sr@!DZ of any cataract in Australia, to describe the factors
#w2;n@7;X related to unoperated cataract in the community and to
qU ESN! describe the visual outcomes of cataract surgery.
["5Z=4 METHODS
e1*<9&S Study population
SZGeF;N Details about the study methodology for the Visual
os=Pr{ Impairment Project have been published previously.11
]QB<N|ps Briefly, cluster sampling within three strata was employed to
j%|#8oV recruit subjects aged 40 years and over to participate.
]{tnNr>mv Within the Melbourne Statistical Division, nine pairs of
942(a census collector districts were randomly selected. Fourteen
+ -
[M 7J nursing homes within a 5 km radius of these nine test sites
zn5U(>=c were randomly chosen to recruit nursing home residents.
jzRfD3_s Clinical and Experimental Ophthalmology (2000) 28, 77–82
/h/f
&3'h Original Article
UODbT&& Operated and unoperated cataract in Australia
}Mh@%2$ Catherine A McCarty PhD, MPH, Mukesh B Nanjan PhD, Hugh R Taylor MD
%/b3G*$W Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
(e:@7W)L n Correspondence: Dr Cathy McCarty MPH, Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, 32 Gisborne Street, East Melbourne,
x1g0_&F Victoria 3002, Australia. Email:
cathy@cera.unimelb.edu.au <W,M?r+
78 McCarty et al.
B@v\tpR Finally, four pairs of census collector districts in four rural
^jY'Hj.Bs Victorian communities were randomly selected to recruit rural
\v7->Sy8 residents. A household census was conducted to identify
6 WD( eligible residents aged 40 years and over who had been a
4$j7DJ8dj resident at that address for at least 6 months. At the time of
@O&<_& the household census, basic information about age, sex,
m :6. country of birth, language spoken at home, education, use of
Ec44JD corrective spectacles and use of eye care services was collected.
br@GnjG Eligible residents were then invited to attend a local
XI4le=^EM examination site for a more detailed interview and examination.
F\!Va The study protocol was approved by the Royal Victorian
L7~9u|7a# Eye and Ear Hospital Human Research Ethics Committee.
-?m"+mUP Assessment of cataract
\!+sL JP A standardized ophthalmic examination was performed after
*.4VO+^ pupil dilatation with one drop of 10% phenylephrine
MLu@|Xgh hydrochloride. Lens opacities were graded clinically at the
$#b@b[h<w time of the examination and subsequently from photos using
=)Aav! the Wilmer cataract photo-grading system.12 Cortical and
b7t
hu5 posterior subcapsular (PSC) opacities were assessed on
l ~b retroillumination and measured as the proportion (in 1/16)
S<
TUZ
/;
of pupil circumference occupied by opacity. For this analysis,
B)q 5m
y cortical cataract was defined as 4/16 or greater opacity,
5:oteNc3 PSC cataract was defined as opacity equal to or greater than
;x]CaG)f 1 mm2 and nuclear cataract was defined as opacity equal to
B) 5QI or greater than Wilmer standard 2,12 independent of visual
il=:T\'U9 acuity. Examples of the minimum opacities defined as cortical,
2 Nr
* nuclear and PSC cataract are presented in Figure 1.
Hp#IOsP~ Bilateral congenital cataracts or cataracts secondary to
O]|T ! intraocular inflammation or trauma were excluded from the
M,uQ8SZA[ analysis. Two cases of bilateral secondary cataract and eight
EFZ]|Z7 cases of bilateral congenital cataract were excluded from the
^ UB*Q analyses.
t08E
2sI A Topcon® SL5 photo slit-lamp (Topcon America Corp.,
JB}jt)ol% Paramus, NJ, USA) with a 0.1 mm slit beam of 9.0 mm in
?}mbp4+j
[ height set to an incident angle of 30° was used for examinations.
a 8(mU% Ektachrome® 200 ASA colour slide film (Eastman
I(bxCiRV Kodak Company, Rochester, NY, USA) was used to photograph
AW\#)Em the nuclear opacities. The cortical opacities were
r+yl{ photographed with an Oxford® retroillumination camera
9fj8r3 F# (Marcher Enterprises Ltd, Hereford, UK) and T-MAX® 400
l-~
o&n film (Eastman Kodak). Photographs were graded separately
r_p4pxs by two research assistants and discrepancies were adjudicated
eHIsTL@Fp by an independent reviewer. Any discrepancies
`~+1i5-} between the clinical grades and the photograph grades were
aRc2#:~; resolved. Except in cases where photographs were missing,
V\2&?#GZ the photograph grades were used in the analyses. Photograph
GIs
*;ps7w grades were available for 4301 (84%) for cortical
*#
7 1aZ cataract, 4147 (81%) for nuclear cataract and 4303 (84%)
ah8xiABa for PSC cataract. Cataract status was classified according to
#P^cR_|\ the severity of the opacity in the worse eye.
_d J"2rx Assessment of risk factors
ZD`
9Ez)5 A standardized questionnaire was used to obtain information
@D3|Ak 1 about education, employment and ethnic background.11
kX1#+X Specific information was elicited on the occurrence, duration
]K^#'[ and treatment of a number of medical conditions,
xDtJ&6uFw including ocular trauma, arthritis, diabetes, gout, hypertension
EPn0ZwnS:M and mental illness. Information about the use, dose and
:'+- %xUM duration of tobacco, alcohol, analgesics and steriods were
@ /yQ4Gr collected, and a food frequency questionnaire was used to
J
Gpy$T{t determine current consumption of dietary sources of antioxidants
IMF9eS{L and use of vitamin supplements.
Bq# l8u Data management and statistical analysis
j_#oP Data were collected either by direct computer entry with a
4Ww.CkRG questionnaire programmed in Paradox© (Carel Corporation,
6.0/asN} Ottawa, Canada) with internal consistency checks, or
kH9fK80 on self-coding forms. Open-ended responses were coded at
y wf@G;
fK a later time. Data that were entered on the self-coded forms
6+Bccqn| were entered into a computer with double data entry and
Rv^
\o
reconciliation of any inconsistencies. Data range and consistency
rT}k[ checks were performed on the entire data set.
t
(sQw '> SAS© version 6.1 (SAS Institute, Cary, North Carolina) was
]
1:pnd employed for statistical analyses.
x]X!nx
6G Ninety-five per cent confidence limits around the agespecific
N:]Ud(VRM rates were calculated according to Cochran13 to
6t0-u
~ account for the effect of the cluster sampling. Ninety-five
]|#%`p56 per cent confidence limits around age-standardized rates
<lxE^M were calculated according to Breslow and Day.14 The strataspecific
^@a|s
Sb data were weighted according to the 1996
__Tg1A Australian Bureau of Statistics census data15 to reflect the
_w\A=6=q| cataract prevalence in the entire Victorian population.
54geU?p0 Univariate analyses with Student’s t-tests and chi-squared
=yy7P[D tests were first employed to evaluate risk factors for unoperated
]!=,8dY cataract. Any factors with P < 0.10 were then fitted
+_E\Omcw into a backwards stepwise logistic regression model. For the
#y4+O;{ Figure 1. Minimum levels of cortical (a), nuclear (b), and posterior subcapsular (c) cataract.
yo=0Ov final multivariate models, P < 0.05 was considered statistically
%=t8 significant. Design effect was assessed through the use
p\&Lbu
zv of cluster-specific models and multivariate models. The
='"hB~[ design effect was assumed to be additive and an adjustment
N)tqjq made in the variance by adding the variance associated with
OU /=w pt the design effect prior to constructing the 95% confidence
tXWhq limits.
2&+Nr+P RESULTS
| @Mx?( Study population
`ywI+^b A total of 3271 (83%) of the Melbourne residents, 403
I\FBf&~ (90%) Melbourne nursing home residents, and 1473 (92%)
Munal=wL rural residents participated. In general, non-participants did
d2!A32m not differ from participants.16 The study population was
6k@(7Mw8A representative of the Victorian population and Australia as
;
wpX a whole.
E/6@>.T?' The Melbourne residents ranged in age from 40 to
HT:
p'Yyi 98 years (mean = 59) and 1511 (46%) were male. The
1m5=Nu Melbourne nursing home residents ranged in age from 46 to
QwaAGUA 101 years (mean = 82) and 85 (21%) were men. The rural
%JsCw8C6? residents ranged in age from 40 to 103 years (mean = 60)
F}C.F and 701 (47.5%) were men.
EG|fGkv" Prevalence of cataract and prior cataract surgery
>cE@m=[ As would be expected, the rate of any cataract increases
8>KBh)q dramatically with age (Table 1). The weighted rate of any
ZI0C%c.~ cataract in Victoria was 21.5% (95% CL 18.1, 24.9).
|~y>R#u8pm Although the rates varied somewhat between the three
CI~P3"`] strata, they were not significantly different as the 95% confidence
0<{zW%w limits overlapped. The per cent of cataractous eyes
;<9 dND with best-corrected visual acuity of less than 6/12 was 12.5%
~$PQ8[= (65/520) for cortical cataract, 18% for nuclear cataract
V:wx@9m) (97/534) and 14.4% (27/187) for PSC cataract. Cataract
dg?[gD8!4& surgery also rose dramatically with age. The overall
wy1xZQ<5 weighted rate of prior cataract surgery in Victoria was
3ZF- n` 3.79% (95% CL 2.97, 4.60) (Table 2).
r@XH=[: Risk factors for unoperated cataract
)U~,q>H+
% Cases of cataract that had not been removed were classified
7a4b,-93 as unoperated cataract. Risk factor analyses for unoperated
sUki|lP cataract were not performed with the nursing home residents
h
dw~AGO# as information about risk factor exposure was not
F_?aoP&5 available for this cohort. The following factors were assessed
k!^Au8Up? in relation to unoperated cataract: age, sex, residence
')8
c (urban/rural), language spoken at home (a measure of ethnic
me7? integration), country of birth, parents’ country of birth (a
,Qd;t measure of ethnicity), years since migration, education, use
Wd R ~ of ophthalmic services, use of optometric services, private
FBR]) h'Z health insurance status, duration of distance glasses use,
mo$`a6[h< glaucoma, age-related maculopathy and employment status.
~; emUU In this cross sectional study it was not possible to assess the
z&3in level of visual acuity that would predict a patient’s having
bm &$wf cataract surgery, as visual acuity data prior to cataract
:dZq!1~t surgery were not available.
#-0}r The significant risk factors for unoperated cataract in univariate
aMxg6\8 analyses were related to: whether a participant had
~.FZF ever seen an optometrist, seen an ophthalmologist or been
d^0vaX6e} diagnosed with glaucoma; and participants’ employment
(.:!_OB0N status (currently employed) and age. These significant
:$>Co\D factors were placed in a backwards stepwise logistic regression
aQMUC6cPM@ model. The factors that remained significantly related
@Qlh to unoperated cataract were whether participants had ever
/!V)2j, seen an ophthalmologist, seen an optometrist and been
':}
diagnosed with glaucoma. None of the demographic factors
:r{;'[38 were associated with unoperated cataract in the multivariate
sS 5aJ}Qs model.
zNF.nS}: The per cent of participants with unoperated cataract
r+4<Lon~ who said that they were dissatisfied or very dissatisfied with
vZDM}u Operated and unoperated cataract in Australia 79
rF/k$_
bFt Table 1. Prevalence of any cataracta (excluding previous cataract surgery) by age, gender and cohort
p~n62( Age group Sex Urban Rural Nursing home Weighted total
-HE@wda (years) (%) (%) (%)
(?G?9M#7_ 40–49 Male 2.56 4.04 0.00 3.00 (1.91, 4.08)
e^N6h3WF Female 2.61 1.70 0.00 2.36 (1.61, 3.10)
aBBTcN%' 50–59 Male 7.69 6.94 0.00 7.47 (5.80, 9.15)
yX-h|Cr" Female 6.67 7.56 0.00 6.92 (5.60, 8.24)
7a,/DI2o 60–69 Male 20.7 25.0 10.0 22.0 (18.1, 26.0)
7$z]oVbO' Female 27.9 35.7 37.5 30.3 (26.0, 34.7)
([mC!d@a 70–79 Male 43.1 58.7 39.1 48.1 (41.2, 55.1)
_P^ xX'v Female 58.6 66.2 55.6 61.0 (56.0, 65.9)
$KmhG1*s 80–89 Male 74.0 89.3 92.0 79.3 (72.3, 86.3)
cZ<@1I5QK Female 91.9 97.0 80.2 92.6 (86.4, 98.8)
.L#xX1qr 90 + Male 100.0 100.0 75.0 98.8 (96.2, 100.0)
L.cGt"{ Female 100.0 100.0 93.8 98.6 (97.0, 100.0)
k*?Axk# Age-standardized
U2lDTRt (95% CL) Combined 19.7 (16.3, 23.1) 23.2 (16.1, 30.2) 16.5 (2.06, 30.9) 21.5 (18.1, 25.0)
ZwC\n(_y aCortical > 4/16, nuclear > standard 2, posterior subcapsular > 1 mm2
w9Eb\
An their current vision was 30% (290/683), compared with 27%
9XH}/FcP_O (26/95) of participants with prior cataract surgery (chisquared,
'Q^P#<< 1 d.f. = 0.25, P = 0.62).
l6[0i Outcomes of cataract surgery
|uT&M`7\{ Two hundred and forty-nine eyes had undergone prior
&!adW@y cataract surgery. Of these 249 operated eyes, 49 (20%) were
gz,x6mnQ left aphakic, 6 (2.4%) had anterior chamber intraocular
]0g$
3 lenses and 194 (78%) had posterior chamber intraocular
C6!P8qX lenses. The rate of capsulotomy in the eyes with intact
H.n
+CR posterior capsules was 36% (73/202). Fifteen per cent of
{<p-/|Z52 eyes (17/114) with a clear posterior capsule had bestcorrected
r8k.I4 visual acuity of less than 6/12 compared with 43%
Ot^<:\<`G of eyes (6/14) with opaque capsules, and 15% of eyes
]tu:V,q (11/73) with prior capsulotomies (chi-squared, 2 d.f. = 7.21,
{m<NPtp910 P = 0.027).
[pc6!qhDG& The percentage of eyes with best-corrected visual acuity
;&A%"8o of 6/12 or better was 96% (302/314) for eyes without
P ]prrKZe, cataract, 88% (1417/1609) for eyes with prevalent cataract
KBb{Z;% and 85% (211/249) for eyes with operated cataract (chisquared,
]Uy
cT3A 2 d.f. = 22.3), P < 0.001). Twenty-seven of the
SviGLv;oR operated eyes (11%) had visual acuities of less than 6/18
`akbzHOM (moderate vision impairment) (Fig. 2). A cause of this
Zl:Z31 moderate visual impairment (but not the only cause) in four
r
N.<S[ (15%) eyes was secondary to cataract surgery. Three of these
opQdym four eyes had undergone intracapsular cataract extraction
bSKe@4C and the fourth eye had an opaque posterior capsule. No one
|.q K69 had bilateral vision impairment as a result of their cataract
v4YY6?4 surgery.
4;_<CB DISCUSSION
2f=7`1RCD To our knowledge, this is the first paper to systematically
s-z*Lq* assess the prevalence of current cataract, previous cataract
(16U]s surgery, predictors of unoperated cataract and the outcomes
DH5]Kzb/ of cataract surgery in a population-based sample. The Visual
Za&.sg3RG Impairment Project is unique in that the sampling frame and
3XOf-v:~ high response rate have ensured that the study population is
TsX(=N_ representative of Australians aged 40 years and over. Therefore,
p{sbf;-x} these data can be used to plan age-related cataract
N?7vcN+-t) services throughout Australia.
+mr\AAFn We found the rate of any cataract in those over the age
SvE|" of 40 years to be 22%. Although relatively high, this rate is
~MgU"P> significantly less than was reported in a number of previous
)/:r$n7 studies,2,4,6 with the exception of the Casteldaccia Eye
K yqFeR Study.5 However, it is difficult to compare rates of cataract
j.5;0b_L^ between studies because of different methodologies and
:=0XT`iY cataract definitions employed in the various studies, as well
U;QN+fF]u as the different age structures of the study populations.
XyS|7#o Other studies have used less conservative definitions of
jMT];%$[ cataract, thus leading to higher rates of cataract as defined.
iTt#%Fs)4M In most large epidemiologic studies of cataract, visual acuity
azUEp8`| has not been included in the definition of cataract.
49BLJ|:P? Therefore, the prevalence of cataract may not reflect the
^aW?0qsH actual need for cataract surgery in the community.
7=o2$ 80 McCarty et al.
Xgy)Z:R Table 2. Prevalence of previous cataract by age, gender and cohort
Cw=wU/) Age group Gender Urban Rural Nursing home Weighted total
$S"QyAH~-a (years) (%) (%) (%)
h%hE$2 40–49 Male 1.14 0.00 0.00 0.80 (0.00, 1.81)
4-?'gN_ Female 0.00 0.00 0.00 0.00 (
xTnd9'Pk`: 50–59 Male 0.68 0.58 0.00 0.65 (0.13, 1.17)
Ozygr?*X Female 0.57 0.00 0.00 0.41 (0.00, 1.00)
yxECK&&P0# 60–69 Male 2.12 7.59 0.00 3.80 (1.41, 6.19)
`q ;79t Female 2.11 3.51 0.00 2.54 (1.81, 3.26)
_t:l:x.;T 70–79 Male 8.22 9.85 8.70 8.75 (6.38, 11.1)
O\5*p=v Female 7.21 7.86 7.02 7.41 (5.36, 9.46)
I92c!`{ 80–89 Male 25.0 30.0 14.3 26.2 (17.0, 35.4)
!eoN Female 27.9 25.6 18.3 26.7 (20.2, 33.3)
LE15y> 90 + Male 0.00 16.7 66.7 9.19 (0.00, 21.5)
!n=@(bT*wT Female 58.3 100.0 26.9 63.1 (44.4, 81.8)
A%VBBvk Age-standardized
q4k
)E (95% CL) Combined 3.31 (2.70, 3.93) 4.36 (2.67, 6.06) 2.26 (0.82, 3.70) 3.79 (2.97, 4.60)
2u[:3K-@, Figure 2. Visual acuity in eyes that had undergone cataract
;w(]z surgery, n = 249. h, Presenting; j, best-corrected.
[;c'o5M& Operated and unoperated cataract in Australia 81
|~!
R5|Q The weighted prevalence of prior cataract surgery in the
Dm@wTt8N( Visual Impairment Project (3.6%) was similar to the crude
s$I
l; rate in the Beaver Dam Eye Study4 (3.1%), but less than the
/H)K_H#|; crude rate in the Blue Mountains Eye Study6 (6.0%).
LE_1H> However, the age-standardized rate in the Blue Mountains
ILUA'T=B0 Eye Study (standardized to the age distribution of the urban
q8:Z.<%8 Visual Impairment Project cohort) was found to be less than
B|IQ/g? the Visual Impairment Project (standardized rate = 1.36%,
ObC 95% CL 1.25, 1.47). The incidence of cataract surgery in
$'f<4 Australia has exceeded population growth.1 This is due,
&bx;GG\<4 perhaps, to advances in surgical techniques and lens
*G^n<p$" implants that have changed the risk–benefit ratio.
hFw\uETu The Global Initiative for the Elimination of Avoidable
s,TKC67.%+ Blindness, sponsored by the World Health Organization,
oZ1#.o{ states that cataract surgical services should be provided that
z_#B 4 ‘have a high success rate in terms of visual outcome and
NyD[9R? improved quality of life’,17 although the ‘high success rate’ is
9
i)E<.6 not defined. Population- and clinic-based studies conducted
-OpI,qyS in the United States have demonstrated marked improvement
tb7Wr1$< in visual acuity following cataract surgery.18–20 We
P>=~\v nN# found that 85% of eyes that had undergone cataract extraction
Y[gj2vNe4g had visual acuity of 6/12 or better. Previously, we have
7?K?-Oj shown that participants with prevalent cataract in this
d"+zDc; cohort are more likely to express dissatisfaction with their
l=5(5
\ current vision than participants without cataract or participants
C~vU with prior cataract surgery.21 In a national study in the
%3'4Qmp
R United States, researchers found that the change in patients’
cA"',N8!5 ratings of their vision difficulties and satisfaction with their
h0NM5 vision after cataract surgery were more highly related to
t=iSMe their change in visual functioning score than to their change
=+q9R`!L] in visual acuity.19 Furthermore, improvement in visual function
GZ\;M6{oh has been shown to be associated with improvement in
[7?K9r\# overall quality of life.22
e# K =SV!H A recent review found that the incidence of visually
_`WbR&d2Id significant posterior capsule opacification following
Q44Pg$jp cataract surgery to be greater than 25%.23 We found 36%
U9IP`)z_5t capsulotomy in our population and that this was associated
@L^2VVWk^ with visual acuity similar to that of eyes with a clear
< pI2} capsule, but significantly better than that of eyes with an
Y((s<]7 opaque capsule.
E;~gQ6vAI A number of studies have shown that the demand and
I!.o
&dk timing of cataract surgery vary according to visual acuity,
7/NXb degree of handicap and socioeconomic factors.8–10,24,25 We
S pDV
D have also shown previously that ophthalmologists are more
Z{`;Ys:zk likely to refer a patient for cataract surgery if the patient is
^8aj\xe( employed and less likely to refer a nursing home resident.7
sM({u/ In the Visual Impairment Project, we did not find that any
L5
"" particular subgroup of the population was at greater risk of
6
k+F
TDL having unoperated cataract. Universal access to health care
CfQOG7e@ in Australia may explain the fact that people without
?hvPPEJf Medicare are more likely to delay cataract operations in the
dlN(_6>b USA,8 but not having private health insurance is not associated
(E59)z - with unoperated cataract in Australia.
VYkOJAEBg In summary, cataract is a significant public health problem
vmL%%7 in that one in four people in their 80s will have had cataract
!7@IWz(," surgery. The importance of age-related cataract surgery will
ed4:r/Dpo increase further with the ageing of the population: the
%5RY Ea number of people over age 60 years is expected to double in
:L&Bbw( the next 20 years. Cataract surgery services are well
V0z.w:- accessed by the Victorian population and the visual outcomes
pj&vnX6O^ of cataract surgery have been shown to be very good.
6#fl1GdH- These data can be used to plan for age-related cataract
ln)_Jf1r surgical services in Australia in the future as the need for
{&8
-OoH ~ cataract extractions increases.
b gGd
ACKNOWLEDGEMENTS
wxVf6` The Visual Impairment Project was funded in part by grants
V"(S<o from the Victorian Health Promotion Foundation, the
s/UIo^m National Health and Medical Research Council, the Ansell
g
!w7Yv Ophthalmology Foundation, the Dorothy Edols Estate and
r^-3( 77n the Jack Brockhoff Foundation. Dr McCarty is the recipient
0e9W>J9 of a Wagstaff Fellowship in Ophthalmology from the Royal
~"!F& Victorian Eye and Ear Hospital.
S{{D G REFERENCES
BbUZ,X*Y 1. Keeffe JE, Taylor HR. Cataract surgery in Australia 1985–94.
o0&jel1a Aust. N.Z. J. Ophthalmol. 1996; 24: 313–17.
Pc
C9)x 2. Sperduto RD, Hiller R. The prevalence of nuclear, cortical,
N,V%/O{Y and posterior subcapsular lens opacities in a general population
D`0II= sample. Ophthalmology 1984; 91: 815–18.
E.Xfb"] 3. Maraini G, Pasquini P, Sperduto RD et al. Distribution of lens
*5 ]fjh{ opacities in the Italian-American case–control study of agerelated
:M9'wg cataract. Ophthalmology 1990; 97: 752–6.
/Z HuT=j1 4. Klein BEK, Klein R, Linton KLP. Prevalence of age-related
."l@aE=| lens opacities in a population. The Beaver Dam Eye Study.
sh[Yu Ophthalmology 1992; 99: 546–52.
iq-n(Rfw~ 5. Guiffrè G, Giammanco R, Di Pace F, Ponte F. Casteldaccia eye
&10vdAnBRC study: prevalence of cataract in the adult and elderly population
v' .:?9 of a Mediterranean town. Int. Ophthalmol. 1995; 18:
Xg?hh 0s 363–71.
qY`)W[ 6. Mitchell P, Cumming RG, Attebo K, Panchapakesan J.
5_ -YF~ Prevalence of cataract in Australia. The Blue Mountains Eye
U(]a(k<r Study. Ophthalmology 1997; 104: 581–8.
C%t~?jEK~^ 7. Keeffe JE, McCarty CA, Chang WP, Steinberg EP, Taylor HR.
)+RTA
y [k Relative importance of VA, patient concern and patient
[
\ LA lifestyle on referral for cataract surgery. Invest. Ophthalmol. Vis.
p#hs8xz Sci. 1996; 37: S183.
gN1b?_g 8. Curbow B, Legro MW, Brenner MH. The influence of patientrelated
F2]v]]F! variables in the timing of cataract extraction. Am. J.
:&}(?=<R}L Ophthalmol. 1993; 115: 614–22.
~Wjm"|c 9. Sletteberg OH, Høvding G, Bertelsen T. Do we operate too
U(3+*'8r,1 many cataracts? The referred cataract patients’ own appraisal
uFOxb}a9v of their need for surgery. Acta Ophthalmol. Scand. 1995; 73:
0? ( 77–80.
sufidi 10. Escarce JJ. Would eliminating differences in physician practice
$D
+6=m[ style reduce geographic variations in cataract surgery rates?
eyf\j,xP& Med. Care 1993; 31: 1106–18.
0'*whhH 11. Livingston PM, Carson CA, Stanislavsky YL, Lee SE, Guest
dqO!p6 CS, Taylor HR. Methods for a population-based study of eye
"- S2${ disease: the Melbourne Visual Impairment Project. Ophthalmic
}NW^?37 Epidemiol. 1994; 1: 139–48.
r,X5@/ 12. Taylor HR, West SK. A simple system for the clinical grading
U1bhd}MoR of lens opacities. Lens Res. 1988; 5: 175–81.
uN20sD} 82 McCarty et al.
8rwkux > 13. Cochran WG. Sampling Techniques. New York: John Wiley &
sE@t$'= Sons, 1977; 249–73.
j@1cllJkh 14. Breslow NE, Day NE. Statistical Methods in Cancer Research. Volume
{I+ II – the Design and Analysis of Cohort Studies. Lyon: International
5
!u.w Agency for Research on Cancer; 1987; 52–61.
;cd{+0 15. Australian Bureau of Statistics. 1996 Census of Population and
8"/
5Lh( Housing. Canberra: Australian Bureau of Statistics, 1997.
R+k-mbvnt 16. Livingston PM, Lee SE, McCarty CA, Taylor HR. A comparison
yPrp:%PS of participants with non-participants in a populationbased
?;@xAj epidemiologic study: the Melbourne Visual Impairment
Z_Jprp{3h Project. Ophthalmic Epidemiol. 1997; 4: 73–82.
im{'PgiR 17. Programme for the Prevention of Blindness. Global Initiative for the
uqwB`<>KJ Elimination of Avoidable Blindness. Geneva: World Health
|P7c { Organization, 1997.
w='1uV<6 18. Applegate WB, Miller ST, Elam JT, Freeman JM, Wood TO,
S6CM/ Gettlefinger TC. Impact of cataract surgery with lens implantation
| n5F_RL on vision and physical function in elderly patients.
d2lOx|jt JAMA 1987; 257: 1064–6.
b:3n)-V{ u 19. Steinberg EP, Tielsch JM, Schein OD et al. National Study of
Gc2sY 0 Cataract Surgery Outcomes. Variation in 4-month postoperative
{|?OKCG{ outcomes as reflected in multiple outcome measures.
a$ a+3}\ Ophthalmology 1994; 101:1131–41.
Li~(kw3 20. Klein BEK, Klein R, Moss SE. Change in visual acuity associated
^ZnlWZ@r with cataract surgery. The Beaver Dam Eye Study.
z3+y|nx! Ophthalmology 1996; 103: 1727–31.
Nf8."EDUW 21. McCarty CA, Keeffe JE, Taylor HR. The need for cataract
= !7k/n'; surgery: projections based on lens opacity, visual acuity, and
!9=hUpRN personal concern. Br. J. Ophthalmol. 1999; 83: 62–5.
Qj: D=j8 22. Brenner MH, Curbow B, Javitt JC, Legro MW, Sommer A.
h-
.V[]< Vision change and quality of life in the elderly. Response to
?95^&4Oh0 cataract surgery and treatment of other ocular conditions.
>m='
#x0>Y Arch. Ophthalmol. 1993; 111: 680–5.
K=Z~$)Og) 23. Schaumberg DA, Dana MR, Christen WG, Glynn RJ. A
{a`t1oX( systematic overview of the incidence of posterior capsule
*(6vO{ opacification. Ophthalmology 1998; 105: 1213–21.
A6ipA/_ 24. Mordue A, Parkin DW, Baxter C, Fawcett G, Stewart M.
h(]aP<49L Thresholds for treatment in cataract surgery. J. Public Health
nEu,1 Med. 1994; 16: 393–8.
*0zdI<Oe 25. Norregaard JC, Bernth-Peterson P, Alonso J et al. Variations in
$;NxO0$ indications for cataract surgery in the United States, Denmark,
B:S/
?v Canada, and Spain: results from the International Cataract
y1R53u`;L Surgery Outcomes Study. Br. J. Ophthalmol. 1998; 82: 1107–11.