ABSTRACT
R~PD[.\u Purpose: To quantify the prevalence of cataract, the outcomes
{OH"d of cataract surgery and the factors related to
=0
mf
unoperated cataract in Australia.
NirG99kyo Methods: Participants were recruited from the Visual
9jBP|I{xI Impairment Project: a cluster, stratified sample of more than
1-.6psE 5000 Victorians aged 40 years and over. At examination
Lzm9Kh; sites interviews, clinical examinations and lens photography
M&wf4)*%0+ were performed. Cataract was defined in participants who
GHaD32 had: had previous cataract surgery, cortical cataract greater
F-D9nI4{X than 4/16, nuclear greater than Wilmer standard 2, or
CD]"Q1
t} posterior subcapsular greater than 1 mm2.
J!YB_6b Results: The participant group comprised 3271 Melbourne
qT5q3 A(8 residents, 403 Melbourne nursing home residents and 1473
CC"}aV5 rural residents.The weighted rate of any cataract in Victoria
waT'|9{ was 21.5%. The overall weighted rate of prior cataract
vgKZr surgery was 3.79%. Two hundred and forty-nine eyes had
=r:(g
a had prior cataract surgery. Of these 249 procedures, 49
AAuH}W>n (20%) were aphakic, 6 (2.4%) had anterior chamber
}$
C;ccWL intraocular lenses and 194 (78%) had posterior chamber
"{>BP$Jz intraocular lenses.Two hundred and eleven of these operated
"Tt5cqUQoY eyes (85%) had best-corrected visual acuity of 6/12 or
w5Lev}Rb better, the legal requirement for a driver’s license.Twentyseven
7n}$|h5D (11%) had visual acuity of less than 6/18 (moderate
2zE gAc vision impairment). Complications of cataract surgery
5!-+5TJI caused reduced vision in four of the 27 eyes (15%), or 1.9%
>L4q>
S^v of operated eyes. Three of these four eyes had undergone
#w]UP#^io intracapsular cataract extraction and the fourth eye had an
H.o=4[ opaque posterior capsule. No one had bilateral vision
=2XAQiUR\ impairment as a result of cataract surgery. Surprisingly, no
}ZqnsLu[) particular demographic factors (such as age, gender, rural
*3@ =XY7 residence, occupation, employment status, health insurance
VcX89c4\ status, ethnicity) were related to the presence of unoperated
8SGqDaRt cataract.
kLE("I:7 Conclusions: Although the overall prevalence of cataract is
emT/5'y quite high, no particular subgroup is systematically underserviced
BFnp[93N in terms of cataract surgery. Overall, the results of
.o#A(3&n cataract surgery are very good, with the majority of eyes
F%< ZEVm achieving driving vision following cataract extraction.
GD-L0kw5 Key words: cataract extraction, health planning, health
{e!3|&AX services accessibility, prevalence
#IvHxSo& INTRODUCTION
0?,<7}"<X Cataract is the leading cause of blindness worldwide and, in
D]=V6l=
Australia, cataract extractions account for the majority of all
EQ [K ophthalmic procedures.1 Over the period 1985–94, the rate
zFi)R }Ot of cataract surgery in Australia was twice as high as would be
`(uN_zvH expected from the growth in the elderly population.1
<s=i5t
My5 Although there have been a number of studies reporting
7S/
\;DF the prevalence of cataract in various populations,2–6 there is
()^tw5e'^ little information about determinants of cataract surgery in
~F"w the population. A previous survey of Australian ophthalmologists
719lfI&s showed that patient concern and lifestyle, rather
f
= 'AI than visual acuity itself, are the primary factors for referral
|mQC-=6t;Y for cataract surgery.7 This supports prior research which has
M{t/B-'4 shown that visual acuity is not a strong predictor of need for
3~%M4( cataract surgery.8,9 Elsewhere, socioeconomic status has
9
lXnNK
|] been shown to be related to cataract surgery rates.10
"cwvx8un To appropriately plan health care services, information is
kx%\Cz needed about the prevalence of age-related cataract in the
GY rUB59 community as well as the factors associated with cataract
R$x(3eyx surgery. The purpose of this study is to quantify the prevalence
B{K_?ae! of any cataract in Australia, to describe the factors
>r>pM(h related to unoperated cataract in the community and to
bE!z[j] describe the visual outcomes of cataract surgery.
Ip0`R+8 METHODS
UNA!vzOb Study population
Y,m=&U Details about the study methodology for the Visual
<uImZC Impairment Project have been published previously.11
&8dj*!4H Briefly, cluster sampling within three strata was employed to
]P2Wa
recruit subjects aged 40 years and over to participate.
2;7n0LOs} Within the Melbourne Statistical Division, nine pairs of
)0\D1IFJ census collector districts were randomly selected. Fourteen
]u\-_PP nursing homes within a 5 km radius of these nine test sites
nj#kzD[n> were randomly chosen to recruit nursing home residents.
zUA
- Clinical and Experimental Ophthalmology (2000) 28, 77–82
U9XOs)^ Original Article
CN6b982& Operated and unoperated cataract in Australia
?]\v%[ho Catherine A McCarty PhD, MPH, Mukesh B Nanjan PhD, Hugh R Taylor MD
gWl49'S>+ Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
8"ulAx74> n Correspondence: Dr Cathy McCarty MPH, Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, 32 Gisborne Street, East Melbourne,
(Bss%\ Victoria 3002, Australia. Email:
cathy@cera.unimelb.edu.au BSY7un+`: 78 McCarty et al.
{A\y4D@ Finally, four pairs of census collector districts in four rural
VO<P9g$UD Victorian communities were randomly selected to recruit rural
loD:4e1 residents. A household census was conducted to identify
t?FPmbjv eligible residents aged 40 years and over who had been a
Bam 4%G5 resident at that address for at least 6 months. At the time of
={I(
i6 the household census, basic information about age, sex,
%.s"l6 W country of birth, language spoken at home, education, use of
mpzm6Ieu corrective spectacles and use of eye care services was collected.
gFxa UrZA Eligible residents were then invited to attend a local
J6J;
!~>_ examination site for a more detailed interview and examination.
npcL<$<6X The study protocol was approved by the Royal Victorian
m$bNQ7 Eye and Ear Hospital Human Research Ethics Committee.
!I Byv%m&\ Assessment of cataract
4K! @9+Mz A standardized ophthalmic examination was performed after
41o~5:& pupil dilatation with one drop of 10% phenylephrine
JjG>$z hydrochloride. Lens opacities were graded clinically at the
KCfcEz time of the examination and subsequently from photos using
}#E~XlX^ the Wilmer cataract photo-grading system.12 Cortical and
\)BDl posterior subcapsular (PSC) opacities were assessed on
vUgo)C#< retroillumination and measured as the proportion (in 1/16)
k^\>=JTq= of pupil circumference occupied by opacity. For this analysis,
MU~nvs;: cortical cataract was defined as 4/16 or greater opacity,
6M@m`c PSC cataract was defined as opacity equal to or greater than
-42jeJS 1 mm2 and nuclear cataract was defined as opacity equal to
_pR7sNe V or greater than Wilmer standard 2,12 independent of visual
u )KtvC! acuity. Examples of the minimum opacities defined as cortical,
xkkW?[& nuclear and PSC cataract are presented in Figure 1.
0& ?/TSC Bilateral congenital cataracts or cataracts secondary to
} @jT-t]P intraocular inflammation or trauma were excluded from the
#zw 'H9l analysis. Two cases of bilateral secondary cataract and eight
q/t~`pH3 cases of bilateral congenital cataract were excluded from the
QP4`r#, analyses.
qEB]Tj e[ A Topcon® SL5 photo slit-lamp (Topcon America Corp.,
xZ(VvINL' Paramus, NJ, USA) with a 0.1 mm slit beam of 9.0 mm in
%-~T;_. height set to an incident angle of 30° was used for examinations.
xnG,1doa Ektachrome® 200 ASA colour slide film (Eastman
|%-:qk4rG Kodak Company, Rochester, NY, USA) was used to photograph
OcGHMGdn the nuclear opacities. The cortical opacities were
ejC== Fkc photographed with an Oxford® retroillumination camera
(eJYv:
^ (Marcher Enterprises Ltd, Hereford, UK) and T-MAX® 400
&l NHNu[ film (Eastman Kodak). Photographs were graded separately
oyY0!w,Y by two research assistants and discrepancies were adjudicated
Yet!qmZ by an independent reviewer. Any discrepancies
aqAWaO between the clinical grades and the photograph grades were
ok7yFm1\ resolved. Except in cases where photographs were missing,
Mlr}v^"G the photograph grades were used in the analyses. Photograph
. ;q4<_ grades were available for 4301 (84%) for cortical
VwV`tKit cataract, 4147 (81%) for nuclear cataract and 4303 (84%)
GS4
HYF for PSC cataract. Cataract status was classified according to
f*^)0Po the severity of the opacity in the worse eye.
ONw;NaE, Assessment of risk factors
-(fvb A standardized questionnaire was used to obtain information
=+j>?Yi about education, employment and ethnic background.11
Q1?G7g]N Specific information was elicited on the occurrence, duration
NuqWezJm& and treatment of a number of medical conditions,
;f7;U=gl, including ocular trauma, arthritis, diabetes, gout, hypertension
>-{)wk;1& and mental illness. Information about the use, dose and
xW;-=Q duration of tobacco, alcohol, analgesics and steriods were
l[q%1-N collected, and a food frequency questionnaire was used to
N{<=s]I%x determine current consumption of dietary sources of antioxidants
oG )JH)! and use of vitamin supplements.
$MEKt}S Data management and statistical analysis
j&.MT@ Data were collected either by direct computer entry with a
@]H:=Q'gj questionnaire programmed in Paradox© (Carel Corporation,
Ex
?)FL$4 Ottawa, Canada) with internal consistency checks, or
1cyX9X on self-coding forms. Open-ended responses were coded at
Q-!a;/ a later time. Data that were entered on the self-coded forms
:>.~"uWo{ were entered into a computer with double data entry and
EQkv&k
5X reconciliation of any inconsistencies. Data range and consistency
6uYCU|JsU checks were performed on the entire data set.
8S>T1st SAS© version 6.1 (SAS Institute, Cary, North Carolina) was
I T)rhi: employed for statistical analyses.
b0CtQe Ninety-five per cent confidence limits around the agespecific
1CiK&fQ'
rates were calculated according to Cochran13 to
@
t account for the effect of the cluster sampling. Ninety-five
qF{u+Ms per cent confidence limits around age-standardized rates
!Q`GA<ikv were calculated according to Breslow and Day.14 The strataspecific
#L{QnV.3 data were weighted according to the 1996
aZYa<28?L% Australian Bureau of Statistics census data15 to reflect the
;wfzlUBC cataract prevalence in the entire Victorian population.
L[d7@ Univariate analyses with Student’s t-tests and chi-squared
Z~tOR{q tests were first employed to evaluate risk factors for unoperated
t]Xdzy cataract. Any factors with P < 0.10 were then fitted
;/W;M> ^ into a backwards stepwise logistic regression model. For the
A-O@e
e Figure 1. Minimum levels of cortical (a), nuclear (b), and posterior subcapsular (c) cataract.
j(!M final multivariate models, P < 0.05 was considered statistically
|2\6X's significant. Design effect was assessed through the use
<h2WM (n of cluster-specific models and multivariate models. The
Da!A1|" design effect was assumed to be additive and an adjustment
_-%A_5lCRE made in the variance by adding the variance associated with
E ?( the design effect prior to constructing the 95% confidence
M SU|
T limits.
-DrR6kGjR RESULTS
maLKUSgo Study population
Dx =ms^oN5 A total of 3271 (83%) of the Melbourne residents, 403
{T
Z7>k (90%) Melbourne nursing home residents, and 1473 (92%)
Z&%#,0>] rural residents participated. In general, non-participants did
"w0> not differ from participants.16 The study population was
1@C0c% representative of the Victorian population and Australia as
FFl[[(`%D a whole.
W6D|Rr.q The Melbourne residents ranged in age from 40 to
E)m{m$Hb 98 years (mean = 59) and 1511 (46%) were male. The
8/*q#j Melbourne nursing home residents ranged in age from 46 to
~]DGf( 101 years (mean = 82) and 85 (21%) were men. The rural
5YaTE<G residents ranged in age from 40 to 103 years (mean = 60)
o&1ewE(O] and 701 (47.5%) were men.
s)#FqB8 Prevalence of cataract and prior cataract surgery
c4oQ4 As would be expected, the rate of any cataract increases
Q0'xn dramatically with age (Table 1). The weighted rate of any
j^T.7Zv cataract in Victoria was 21.5% (95% CL 18.1, 24.9).
4
mJ4) Although the rates varied somewhat between the three
ps"DL4* strata, they were not significantly different as the 95% confidence
LY[XPV]t limits overlapped. The per cent of cataractous eyes
=vMFCp;mv with best-corrected visual acuity of less than 6/12 was 12.5%
W[[3'J TF (65/520) for cortical cataract, 18% for nuclear cataract
o ^L3Xiv (97/534) and 14.4% (27/187) for PSC cataract. Cataract
>S3iP?V7 surgery also rose dramatically with age. The overall
@FKNB.> weighted rate of prior cataract surgery in Victoria was
.{x-A{l 3.79% (95% CL 2.97, 4.60) (Table 2).
uPc}a3'? Risk factors for unoperated cataract
L6Ykv/V Cases of cataract that had not been removed were classified
-;cZW.< as unoperated cataract. Risk factor analyses for unoperated
l=U@j
T cataract were not performed with the nursing home residents
+0\BI<aG as information about risk factor exposure was not
?9nuL}m!a available for this cohort. The following factors were assessed
5v"QKI in relation to unoperated cataract: age, sex, residence
ZIQy}b' (urban/rural), language spoken at home (a measure of ethnic
bB@1tp0+ integration), country of birth, parents’ country of birth (a
ya3A^&: measure of ethnicity), years since migration, education, use
,\q9>cZ! of ophthalmic services, use of optometric services, private
ED&>~~k) health insurance status, duration of distance glasses use,
yKF"\^`@ glaucoma, age-related maculopathy and employment status.
2apR7 In this cross sectional study it was not possible to assess the
=#dW^?p level of visual acuity that would predict a patient’s having
a]-F,M J cataract surgery, as visual acuity data prior to cataract
}.ZX.qYX surgery were not available.
#4iSQ$0 The significant risk factors for unoperated cataract in univariate
awh<CmcZ analyses were related to: whether a participant had
kx0(v1y3gT ever seen an optometrist, seen an ophthalmologist or been
^.)oQo SE diagnosed with glaucoma; and participants’ employment
] W39HL status (currently employed) and age. These significant
"vI:B} factors were placed in a backwards stepwise logistic regression
6U5L>sQ model. The factors that remained significantly related
N|-M|1w96 to unoperated cataract were whether participants had ever
LdnHz# seen an ophthalmologist, seen an optometrist and been
xR}^~14Bz diagnosed with glaucoma. None of the demographic factors
'4k
l$I were associated with unoperated cataract in the multivariate
){^o"A?-: model.
fNe9as The per cent of participants with unoperated cataract
;:2]++G who said that they were dissatisfied or very dissatisfied with
Qc1NLU9: Operated and unoperated cataract in Australia 79
ieuq9ah# Table 1. Prevalence of any cataracta (excluding previous cataract surgery) by age, gender and cohort
`&y Qtj#
' Age group Sex Urban Rural Nursing home Weighted total
J=?`~?Vbo (years) (%) (%) (%)
B8A-|S!,U 40–49 Male 2.56 4.04 0.00 3.00 (1.91, 4.08)
zA/tHlKc Female 2.61 1.70 0.00 2.36 (1.61, 3.10)
QS(aA*D 50–59 Male 7.69 6.94 0.00 7.47 (5.80, 9.15)
Q(v*I&k Female 6.67 7.56 0.00 6.92 (5.60, 8.24)
`o|Y5wQ@ 60–69 Male 20.7 25.0 10.0 22.0 (18.1, 26.0)
Ai>=n; Female 27.9 35.7 37.5 30.3 (26.0, 34.7)
Wk<he F 70–79 Male 43.1 58.7 39.1 48.1 (41.2, 55.1)
[ye!3h&] Female 58.6 66.2 55.6 61.0 (56.0, 65.9)
-u+@5K;^Y 80–89 Male 74.0 89.3 92.0 79.3 (72.3, 86.3)
_mSDz=!Z3 Female 91.9 97.0 80.2 92.6 (86.4, 98.8)
VPOzt7: 90 + Male 100.0 100.0 75.0 98.8 (96.2, 100.0)
6!F@?3qCyg Female 100.0 100.0 93.8 98.6 (97.0, 100.0)
].ZfTrM] Age-standardized
` mvPbZ0< (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)
E3..$x-/ aCortical > 4/16, nuclear > standard 2, posterior subcapsular > 1 mm2
P;~`%,+S their current vision was 30% (290/683), compared with 27%
a
]~Rp (26/95) of participants with prior cataract surgery (chisquared,
L
As#g||M 1 d.f. = 0.25, P = 0.62).
o
,qq*}= Outcomes of cataract surgery
hSAdD! Two hundred and forty-nine eyes had undergone prior
RB
Ob/.$ cataract surgery. Of these 249 operated eyes, 49 (20%) were
D;?cf+6$ left aphakic, 6 (2.4%) had anterior chamber intraocular
tL#~U2K lenses and 194 (78%) had posterior chamber intraocular
6=pE5UfT lenses. The rate of capsulotomy in the eyes with intact
S7!+8$2mc_ posterior capsules was 36% (73/202). Fifteen per cent of
I1f4u6\*X eyes (17/114) with a clear posterior capsule had bestcorrected
O$eNG$7 visual acuity of less than 6/12 compared with 43%
6DkFI
kS of eyes (6/14) with opaque capsules, and 15% of eyes
SI)QX\is8 (11/73) with prior capsulotomies (chi-squared, 2 d.f. = 7.21,
Fal##6B P = 0.027).
,|}}Ml The percentage of eyes with best-corrected visual acuity
+DsdzR`Gx, of 6/12 or better was 96% (302/314) for eyes without
~`Y!_ '(x cataract, 88% (1417/1609) for eyes with prevalent cataract
o}4~CN9} and 85% (211/249) for eyes with operated cataract (chisquared,
a^vTBJXo 2 d.f. = 22.3), P < 0.001). Twenty-seven of the
{<}9r6k;f operated eyes (11%) had visual acuities of less than 6/18
!+Fr U'^ (moderate vision impairment) (Fig. 2). A cause of this
'^|u\$&U moderate visual impairment (but not the only cause) in four
8(zE^W,[8" (15%) eyes was secondary to cataract surgery. Three of these
!-veL1r four eyes had undergone intracapsular cataract extraction
WrHY' and the fourth eye had an opaque posterior capsule. No one
WEaG/)y had bilateral vision impairment as a result of their cataract
m{gw:69h surgery.
BQ:hUF3 DISCUSSION
eae `#>XP To our knowledge, this is the first paper to systematically
?S<`*O
+ assess the prevalence of current cataract, previous cataract
\Ota~A surgery, predictors of unoperated cataract and the outcomes
^7Rc\ of cataract surgery in a population-based sample. The Visual
5i@WBa Impairment Project is unique in that the sampling frame and
Jn&^5,J]F8 high response rate have ensured that the study population is
pi|=3W representative of Australians aged 40 years and over. Therefore,
f6,?Yex8B these data can be used to plan age-related cataract
OWys`2W services throughout Australia.
$5wf{iZY.Q We found the rate of any cataract in those over the age
`N}aV Ns of 40 years to be 22%. Although relatively high, this rate is
~@\sN+VS significantly less than was reported in a number of previous
GU|(m~,` studies,2,4,6 with the exception of the Casteldaccia Eye
I=pFGU Study.5 However, it is difficult to compare rates of cataract
`%/w0,0 between studies because of different methodologies and
Y 8n*o3jM cataract definitions employed in the various studies, as well
oCxy(q'y as the different age structures of the study populations.
n_{az{~ Other studies have used less conservative definitions of
K=Z.<f cataract, thus leading to higher rates of cataract as defined.
l4>c In most large epidemiologic studies of cataract, visual acuity
/E-sg,
k
has not been included in the definition of cataract.
#O lPnP 2 Therefore, the prevalence of cataract may not reflect the
hCb2<_3CR actual need for cataract surgery in the community.
0VZC7@ 80 McCarty et al.
$-p9cyk Table 2. Prevalence of previous cataract by age, gender and cohort
^kK% 8 u Age group Gender Urban Rural Nursing home Weighted total
8shx7" (years) (%) (%) (%)
h0?w V5H 40–49 Male 1.14 0.00 0.00 0.80 (0.00, 1.81)
9&bJ] Female 0.00 0.00 0.00 0.00 (
NM"5.
50–59 Male 0.68 0.58 0.00 0.65 (0.13, 1.17)
Pj1 k?7 Female 0.57 0.00 0.00 0.41 (0.00, 1.00)
"vX\Q rL 60–69 Male 2.12 7.59 0.00 3.80 (1.41, 6.19)
vSy[lB|)24 Female 2.11 3.51 0.00 2.54 (1.81, 3.26)
^'n;W<\p) 70–79 Male 8.22 9.85 8.70 8.75 (6.38, 11.1)
)O2IEwPd. Female 7.21 7.86 7.02 7.41 (5.36, 9.46)
N9s+Tm 80–89 Male 25.0 30.0 14.3 26.2 (17.0, 35.4)
q8!]x-5$6j Female 27.9 25.6 18.3 26.7 (20.2, 33.3)
*c>B-Fo/D 90 + Male 0.00 16.7 66.7 9.19 (0.00, 21.5)
8#w%qij Female 58.3 100.0 26.9 63.1 (44.4, 81.8)
<.2jQ#So Age-standardized
=ea.+ (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)
n]6-`fpD Figure 2. Visual acuity in eyes that had undergone cataract
T!
I3. surgery, n = 249. h, Presenting; j, best-corrected.
DYoGtks( Operated and unoperated cataract in Australia 81
{:|b,ep
T The weighted prevalence of prior cataract surgery in the
!;4Hh)2 Visual Impairment Project (3.6%) was similar to the crude
K
$WMrp rate in the Beaver Dam Eye Study4 (3.1%), but less than the
CDPu(,^ crude rate in the Blue Mountains Eye Study6 (6.0%).
wD:2sri However, the age-standardized rate in the Blue Mountains
~uV(/?o% Eye Study (standardized to the age distribution of the urban
PuhvJHT Visual Impairment Project cohort) was found to be less than
*
F_KOf9p the Visual Impairment Project (standardized rate = 1.36%,
w:/3%- 95% CL 1.25, 1.47). The incidence of cataract surgery in
CvR-lKV< Australia has exceeded population growth.1 This is due,
T2n3g|4 perhaps, to advances in surgical techniques and lens
1:r#m- \ implants that have changed the risk–benefit ratio.
O~v~s
'c& The Global Initiative for the Elimination of Avoidable
K&,";9c Blindness, sponsored by the World Health Organization,
f-634KuP states that cataract surgical services should be provided that
K9 ]zUew ‘have a high success rate in terms of visual outcome and
&8Z.m,s] improved quality of life’,17 although the ‘high success rate’ is
T|0+o+i not defined. Population- and clinic-based studies conducted
LlS~J K in the United States have demonstrated marked improvement
C#4_`4{ in visual acuity following cataract surgery.18–20 We
IA{W-RRb found that 85% of eyes that had undergone cataract extraction
=6+99<G|%M had visual acuity of 6/12 or better. Previously, we have
L^zh|MEyzk shown that participants with prevalent cataract in this
}dHdy{$ cohort are more likely to express dissatisfaction with their
lD, ~% current vision than participants without cataract or participants
L`e19I$ with prior cataract surgery.21 In a national study in the
V#5$J Xp United States, researchers found that the change in patients’
Vh>cV ratings of their vision difficulties and satisfaction with their
UG=]8YY!
vision after cataract surgery were more highly related to
GKjtX?~1 their change in visual functioning score than to their change
=Xg/[J% in visual acuity.19 Furthermore, improvement in visual function
4P"bOt5izR has been shown to be associated with improvement in
5&h">_j overall quality of life.22
"DA%vdu A recent review found that the incidence of visually
01n132k significant posterior capsule opacification following
=<#G~8WYz cataract surgery to be greater than 25%.23 We found 36%
T1*.3_wtP capsulotomy in our population and that this was associated
K!.t}s.t with visual acuity similar to that of eyes with a clear
EFljUT?& capsule, but significantly better than that of eyes with an
1^2Q`~,g opaque capsule.
5OtdB'UITd A number of studies have shown that the demand and
l_yF;5|?z timing of cataract surgery vary according to visual acuity,
3l45(%g+ degree of handicap and socioeconomic factors.8–10,24,25 We
w$AR have also shown previously that ophthalmologists are more
-4sKB>b likely to refer a patient for cataract surgery if the patient is
<+-n
lK4 employed and less likely to refer a nursing home resident.7
^/#G,MxNy In the Visual Impairment Project, we did not find that any
83SK<V6 particular subgroup of the population was at greater risk of
kY'Wf`y( having unoperated cataract. Universal access to health care
Q}OloA(+ in Australia may explain the fact that people without
>e
R^G5rn; Medicare are more likely to delay cataract operations in the
GT)7VF rL USA,8 but not having private health insurance is not associated
!
CcDA/0 with unoperated cataract in Australia.
rU&Y/ In summary, cataract is a significant public health problem
iiMS3ueF in that one in four people in their 80s will have had cataract
7xv9v1[' surgery. The importance of age-related cataract surgery will
N+B!AK0. increase further with the ageing of the population: the
qar{*>LCG number of people over age 60 years is expected to double in
GT6i9*tb# the next 20 years. Cataract surgery services are well
1' U
accessed by the Victorian population and the visual outcomes
VGD~) z57 of cataract surgery have been shown to be very good.
7=^}{ These data can be used to plan for age-related cataract
o]Ne|PEpO surgical services in Australia in the future as the need for
T@U,<[, cataract extractions increases.
1:](=%oM&k ACKNOWLEDGEMENTS
#f24a?n| The Visual Impairment Project was funded in part by grants
7<!x:G?C from the Victorian Health Promotion Foundation, the
KFHZ3HZ:> National Health and Medical Research Council, the Ansell
eG!ma` v Ophthalmology Foundation, the Dorothy Edols Estate and
*)-@'{]u B the Jack Brockhoff Foundation. Dr McCarty is the recipient
<3BGW?=WP of a Wagstaff Fellowship in Ophthalmology from the Royal
CU\gx*=E Victorian Eye and Ear Hospital.
j67ppt REFERENCES
Lk,q~
1. Keeffe JE, Taylor HR. Cataract surgery in Australia 1985–94.
|~
fI=1;;x Aust. N.Z. J. Ophthalmol. 1996; 24: 313–17.
tm.60udbo 2. Sperduto RD, Hiller R. The prevalence of nuclear, cortical,
9 ;p5z[jI and posterior subcapsular lens opacities in a general population
M-i3_H) sample. Ophthalmology 1984; 91: 815–18.
2I_ yUt- 3. Maraini G, Pasquini P, Sperduto RD et al. Distribution of lens
o/o6|[=3 opacities in the Italian-American case–control study of agerelated
vRC >=y*= cataract. Ophthalmology 1990; 97: 752–6.
,4t6Cq! 4. Klein BEK, Klein R, Linton KLP. Prevalence of age-related
6_KvS lens opacities in a population. The Beaver Dam Eye Study.
gR# k' Ophthalmology 1992; 99: 546–52.
g{6jN 5. Guiffrè G, Giammanco R, Di Pace F, Ponte F. Casteldaccia eye
~9FL]qo study: prevalence of cataract in the adult and elderly population
ub~ t
} of a Mediterranean town. Int. Ophthalmol. 1995; 18:
[?I<$f" 363–71.
OS@uGp=
6. Mitchell P, Cumming RG, Attebo K, Panchapakesan J.
NT5=%X] Prevalence of cataract in Australia. The Blue Mountains Eye
:Q("
Study. Ophthalmology 1997; 104: 581–8.
E|c(#P{ 7. Keeffe JE, McCarty CA, Chang WP, Steinberg EP, Taylor HR.
%_5#2a Relative importance of VA, patient concern and patient
3W[?D8yi) lifestyle on referral for cataract surgery. Invest. Ophthalmol. Vis.
U&BCd$ Sci. 1996; 37: S183.
T(x@gwc 8. Curbow B, Legro MW, Brenner MH. The influence of patientrelated
@,.D]43 variables in the timing of cataract extraction. Am. J.
kh.P)h'9 Ophthalmol. 1993; 115: 614–22.
wW*7 9. Sletteberg OH, Høvding G, Bertelsen T. Do we operate too
rHw#<oV many cataracts? The referred cataract patients’ own appraisal
fEL 9J{ of their need for surgery. Acta Ophthalmol. Scand. 1995; 73:
9!X3Cv|+L 77–80.
G8+&fn6 10. Escarce JJ. Would eliminating differences in physician practice
|3e+ K. style reduce geographic variations in cataract surgery rates?
oFP8s[B Med. Care 1993; 31: 1106–18.
E5rV}>(Y 11. Livingston PM, Carson CA, Stanislavsky YL, Lee SE, Guest
hQj@D\} CS, Taylor HR. Methods for a population-based study of eye
T}^3 Re`i disease: the Melbourne Visual Impairment Project. Ophthalmic
(o B4* Epidemiol. 1994; 1: 139–48.
7BU7sQjs 12. Taylor HR, West SK. A simple system for the clinical grading
H5Eso*v@ of lens opacities. Lens Res. 1988; 5: 175–81.
G1j
j:]1 82 McCarty et al.
VrPsy) J68 13. Cochran WG. Sampling Techniques. New York: John Wiley &
./XX Sons, 1977; 249–73.
;@qS#7SRB 14. Breslow NE, Day NE. Statistical Methods in Cancer Research. Volume
k/{WlLN II – the Design and Analysis of Cohort Studies. Lyon: International
vwu/33 Agency for Research on Cancer; 1987; 52–61.
ni{'V4A 15. Australian Bureau of Statistics. 1996 Census of Population and
C `_/aR6 Housing. Canberra: Australian Bureau of Statistics, 1997.
uc+{<E3,% 16. Livingston PM, Lee SE, McCarty CA, Taylor HR. A comparison
_x(hlHFk of participants with non-participants in a populationbased
GgY8\>u epidemiologic study: the Melbourne Visual Impairment
k)7i^1U Project. Ophthalmic Epidemiol. 1997; 4: 73–82.
rwXpB<@l@ 17. Programme for the Prevention of Blindness. Global Initiative for the
50Gr\ Elimination of Avoidable Blindness. Geneva: World Health
WcqR; Nm Organization, 1997.
KJQ8Yhq 18. Applegate WB, Miller ST, Elam JT, Freeman JM, Wood TO,
%pq.fZI Gettlefinger TC. Impact of cataract surgery with lens implantation
6vbKKn`ST on vision and physical function in elderly patients.
<}[ !k< JAMA 1987; 257: 1064–6.
4!{lySW 19. Steinberg EP, Tielsch JM, Schein OD et al. National Study of
?[ )}N
_o# Cataract Surgery Outcomes. Variation in 4-month postoperative
d)-ZL*o outcomes as reflected in multiple outcome measures.
=5Db^ Ophthalmology 1994; 101:1131–41.
z9IW&f~~P 20. Klein BEK, Klein R, Moss SE. Change in visual acuity associated
c>D~MCNxg with cataract surgery. The Beaver Dam Eye Study.
T2Z$*;,>T Ophthalmology 1996; 103: 1727–31.
G 0pq'7B 21. McCarty CA, Keeffe JE, Taylor HR. The need for cataract
u~uz=Yse surgery: projections based on lens opacity, visual acuity, and
Kt*b)
< personal concern. Br. J. Ophthalmol. 1999; 83: 62–5.
g^A^@~M 22. Brenner MH, Curbow B, Javitt JC, Legro MW, Sommer A.
z8a{M$-Q Vision change and quality of life in the elderly. Response to
Wo&22,EB cataract surgery and treatment of other ocular conditions.
"W6cQsi Arch. Ophthalmol. 1993; 111: 680–5.
el5Pe{j' 23. Schaumberg DA, Dana MR, Christen WG, Glynn RJ. A
s:6K
'* systematic overview of the incidence of posterior capsule
IQ\!wWKmY opacification. Ophthalmology 1998; 105: 1213–21.
ib(|}7Je 24. Mordue A, Parkin DW, Baxter C, Fawcett G, Stewart M.
I>.pkf<V Thresholds for treatment in cataract surgery. J. Public Health
BEb?jRMjLg Med. 1994; 16: 393–8.
2H$](k?
25. Norregaard JC, Bernth-Peterson P, Alonso J et al. Variations in
Pq+|*Y<|& indications for cataract surgery in the United States, Denmark,
b
X38=.up Canada, and Spain: results from the International Cataract
b&`~%f-
Surgery Outcomes Study. Br. J. Ophthalmol. 1998; 82: 1107–11.