ABSTRACT
W!V06
. Purpose: To quantify the prevalence of cataract, the outcomes
+
ECV|mkk of cataract surgery and the factors related to
_sJp"4? unoperated cataract in Australia.
~Og'IRf Methods: Participants were recruited from the Visual
*+lnAxRa? Impairment Project: a cluster, stratified sample of more than
FHqa|4Ie 5000 Victorians aged 40 years and over. At examination
$Y)|&, sites interviews, clinical examinations and lens photography
OJQ7nChMm were performed. Cataract was defined in participants who
J1yy6Wq3[ had: had previous cataract surgery, cortical cataract greater
pBh[F5 than 4/16, nuclear greater than Wilmer standard 2, or
v #IC posterior subcapsular greater than 1 mm2.
3zMmpeq Results: The participant group comprised 3271 Melbourne
<o^mQq& residents, 403 Melbourne nursing home residents and 1473
N@Bqe{r6j rural residents.The weighted rate of any cataract in Victoria
Dbz\8gmY was 21.5%. The overall weighted rate of prior cataract
%`-NWAXL surgery was 3.79%. Two hundred and forty-nine eyes had
!fyE
Hk had prior cataract surgery. Of these 249 procedures, 49
{b7P1}>-* (20%) were aphakic, 6 (2.4%) had anterior chamber
hDjsGB|Fz intraocular lenses and 194 (78%) had posterior chamber
0 l
G\
QT intraocular lenses.Two hundred and eleven of these operated
6@; w%Ea eyes (85%) had best-corrected visual acuity of 6/12 or
>2Z:=H
T better, the legal requirement for a driver’s license.Twentyseven
4VD'<`R[ (11%) had visual acuity of less than 6/18 (moderate
E!C~*l]wJx vision impairment). Complications of cataract surgery
6aXsRhQ~ caused reduced vision in four of the 27 eyes (15%), or 1.9%
>x(^g~i of operated eyes. Three of these four eyes had undergone
/p?h@6h@y intracapsular cataract extraction and the fourth eye had an
OKxPf]~4E opaque posterior capsule. No one had bilateral vision
V92e#AR impairment as a result of cataract surgery. Surprisingly, no
(y=P-nm particular demographic factors (such as age, gender, rural
Kc}FMu residence, occupation, employment status, health insurance
?v8B;="#w status, ethnicity) were related to the presence of unoperated
onHUi]yYu{ cataract.
F~)xZN3= Conclusions: Although the overall prevalence of cataract is
G{YJ(6etZ quite high, no particular subgroup is systematically underserviced
Gk'J'9* in terms of cataract surgery. Overall, the results of
X;6&:%ZL@^ cataract surgery are very good, with the majority of eyes
y85GKysT achieving driving vision following cataract extraction.
By:A9s Key words: cataract extraction, health planning, health
`cMa Fc-y/ services accessibility, prevalence
b"/P
INTRODUCTION
rR^VW^|f Cataract is the leading cause of blindness worldwide and, in
"<txg%j\J Australia, cataract extractions account for the majority of all
O`rAqO0F ophthalmic procedures.1 Over the period 1985–94, the rate
| t3_E of cataract surgery in Australia was twice as high as would be
pc:~_6S expected from the growth in the elderly population.1
[1G4he% Although there have been a number of studies reporting
RVlC8uJ;P the prevalence of cataract in various populations,2–6 there is
vb\ UP&Ip little information about determinants of cataract surgery in
{UvZ the population. A previous survey of Australian ophthalmologists
@]
gP"Pp showed that patient concern and lifestyle, rather
u=p([
5] than visual acuity itself, are the primary factors for referral
xBl}=M?Qu for cataract surgery.7 This supports prior research which has
X3<<f`X shown that visual acuity is not a strong predictor of need for
G %Wjtrpj cataract surgery.8,9 Elsewhere, socioeconomic status has
Aum&U){yY been shown to be related to cataract surgery rates.10
P)7SK&]r;= To appropriately plan health care services, information is
D}&U3?g= needed about the prevalence of age-related cataract in the
SHIK=&\~- community as well as the factors associated with cataract
`G@]\)-! surgery. The purpose of this study is to quantify the prevalence
at/bes W of any cataract in Australia, to describe the factors
,4)zn6tC related to unoperated cataract in the community and to
v0apEjT describe the visual outcomes of cataract surgery.
:BNqr[=b METHODS
pbl;n| Study population
l]uF!']f Details about the study methodology for the Visual
k-*H=km Impairment Project have been published previously.11
OLXG0@ Briefly, cluster sampling within three strata was employed to
"6FZX~]s! recruit subjects aged 40 years and over to participate.
oDrfzm|[Y Within the Melbourne Statistical Division, nine pairs of
~Yb5FYE census collector districts were randomly selected. Fourteen
`!K(P- yB? nursing homes within a 5 km radius of these nine test sites
kL*
DU` were randomly chosen to recruit nursing home residents.
9B{,q6 Clinical and Experimental Ophthalmology (2000) 28, 77–82
-2{NI.-Xd Original Article
J4;w9[a$ Operated and unoperated cataract in Australia
!NuiVC] Catherine A McCarty PhD, MPH, Mukesh B Nanjan PhD, Hugh R Taylor MD
0L S,(v4 Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
; {iX_% n Correspondence: Dr Cathy McCarty MPH, Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, 32 Gisborne Street, East Melbourne,
zgI!S6q Victoria 3002, Australia. Email:
cathy@cera.unimelb.edu.au *%=BcV+, 78 McCarty et al.
zogw1g&C Finally, four pairs of census collector districts in four rural
I}q2)@ Victorian communities were randomly selected to recruit rural
-K eoq residents. A household census was conducted to identify
:tBIo7 eligible residents aged 40 years and over who had been a
#I8)|p?P resident at that address for at least 6 months. At the time of
b"H
c==` the household census, basic information about age, sex,
f>!)y- 7 country of birth, language spoken at home, education, use of
kw{dvE\K corrective spectacles and use of eye care services was collected.
C~-x637/ Eligible residents were then invited to attend a local
{ R
H&mu examination site for a more detailed interview and examination.
tg-U x The study protocol was approved by the Royal Victorian
fIe';a Eye and Ear Hospital Human Research Ethics Committee.
QOiPDu=8z Assessment of cataract
(KxI* A standardized ophthalmic examination was performed after
M$_E:u&D pupil dilatation with one drop of 10% phenylephrine
kb3>q($ hydrochloride. Lens opacities were graded clinically at the
Cm@rXA/ time of the examination and subsequently from photos using
7>.d*?eao\ the Wilmer cataract photo-grading system.12 Cortical and
yX9 .yq posterior subcapsular (PSC) opacities were assessed on
" GRR,7A retroillumination and measured as the proportion (in 1/16)
qlSI| @CO of pupil circumference occupied by opacity. For this analysis,
X1*f#3cm# cortical cataract was defined as 4/16 or greater opacity,
&s6;2G&L$ PSC cataract was defined as opacity equal to or greater than
`A
\,$(q+ 1 mm2 and nuclear cataract was defined as opacity equal to
'3<T~t or greater than Wilmer standard 2,12 independent of visual
de=){.7Y acuity. Examples of the minimum opacities defined as cortical,
B7x(<!B nuclear and PSC cataract are presented in Figure 1.
s>J\h Bilateral congenital cataracts or cataracts secondary to
B(|*u intraocular inflammation or trauma were excluded from the
tTEw"DL_- analysis. Two cases of bilateral secondary cataract and eight
$8>kk cases of bilateral congenital cataract were excluded from the
AQ%B&Q(V1 analyses.
GF
GW'}w- A Topcon® SL5 photo slit-lamp (Topcon America Corp.,
K_!R Paramus, NJ, USA) with a 0.1 mm slit beam of 9.0 mm in
YCl&}/.pA height set to an incident angle of 30° was used for examinations.
e5AZU7%. Ektachrome® 200 ASA colour slide film (Eastman
h"0)g:\ Kodak Company, Rochester, NY, USA) was used to photograph
&?[g8A the nuclear opacities. The cortical opacities were
!;3hN$5 photographed with an Oxford® retroillumination camera
A"tE~m;"7 (Marcher Enterprises Ltd, Hereford, UK) and T-MAX® 400
m!5MGq~ film (Eastman Kodak). Photographs were graded separately
!78P+i by two research assistants and discrepancies were adjudicated
[][ze2+b by an independent reviewer. Any discrepancies
?B+]Ex(\B, between the clinical grades and the photograph grades were
d\ I6Wn resolved. Except in cases where photographs were missing,
.oS[ DTn5S the photograph grades were used in the analyses. Photograph
Mfn^v:Q# grades were available for 4301 (84%) for cortical
8vkCmV cataract, 4147 (81%) for nuclear cataract and 4303 (84%)
'yo-`nNFD for PSC cataract. Cataract status was classified according to
Tnv,$KOhs the severity of the opacity in the worse eye.
P b-4$n2c
Assessment of risk factors
enGZb& A standardized questionnaire was used to obtain information
' hDs.Wnu
about education, employment and ethnic background.11
2T?8{yO7 Specific information was elicited on the occurrence, duration
DHg)]FQ/ and treatment of a number of medical conditions,
B&QEt[=s including ocular trauma, arthritis, diabetes, gout, hypertension
)[ QT?; and mental illness. Information about the use, dose and
}Ug$d>\ duration of tobacco, alcohol, analgesics and steriods were
q`Vk
A
\ collected, and a food frequency questionnaire was used to
5g%D0_e5 determine current consumption of dietary sources of antioxidants
pocXQEg$] and use of vitamin supplements.
+B[XTn,Cru Data management and statistical analysis
C#V_Gb Data were collected either by direct computer entry with a
OI_Px3)
y questionnaire programmed in Paradox© (Carel Corporation,
-mP2}BNM Ottawa, Canada) with internal consistency checks, or
]VR79l on self-coding forms. Open-ended responses were coded at
-_xTs(;|8 a later time. Data that were entered on the self-coded forms
Q4Nut were entered into a computer with double data entry and
Ei<m/v
reconciliation of any inconsistencies. Data range and consistency
~g9~D}48k' checks were performed on the entire data set.
v.ow`MO=; SAS© version 6.1 (SAS Institute, Cary, North Carolina) was
Uw]o9 e0S employed for statistical analyses.
#
0d7 Ninety-five per cent confidence limits around the agespecific
1,Es' rates were calculated according to Cochran13 to
KjMwrMgC account for the effect of the cluster sampling. Ninety-five
R, #szTu per cent confidence limits around age-standardized rates
B8unF=u were calculated according to Breslow and Day.14 The strataspecific
m70AWG data were weighted according to the 1996
D9H%jDv Australian Bureau of Statistics census data15 to reflect the
'[HBKn$` cataract prevalence in the entire Victorian population.
Y3#8]Z_"}O Univariate analyses with Student’s t-tests and chi-squared
n!sOKw tests were first employed to evaluate risk factors for unoperated
&1Y7Ne cataract. Any factors with P < 0.10 were then fitted
WZn"I&Z into a backwards stepwise logistic regression model. For the
}+}Cl T Figure 1. Minimum levels of cortical (a), nuclear (b), and posterior subcapsular (c) cataract.
(0l>P]"n final multivariate models, P < 0.05 was considered statistically
l*(L"] significant. Design effect was assessed through the use
}
@
[!%hE of cluster-specific models and multivariate models. The
+U<.MVOo. design effect was assumed to be additive and an adjustment
~;-2eKw made in the variance by adding the variance associated with
@NiLKcL# the design effect prior to constructing the 95% confidence
Xgl
%2' limits.
&G[W$2`@ RESULTS
++UxzUd Study population
|z8_]o+|r1 A total of 3271 (83%) of the Melbourne residents, 403
eY%Ep=J (90%) Melbourne nursing home residents, and 1473 (92%)
dKP| TRd rural residents participated. In general, non-participants did
oKr= ]p not differ from participants.16 The study population was
]T(qk representative of the Victorian population and Australia as
@Z7s3b a whole.
?)[=>Kp The Melbourne residents ranged in age from 40 to
B
qINU 98 years (mean = 59) and 1511 (46%) were male. The
4uh~@ Lv Melbourne nursing home residents ranged in age from 46 to
,Y#f0 101 years (mean = 82) and 85 (21%) were men. The rural
APJFy@l} residents ranged in age from 40 to 103 years (mean = 60)
VZe'6?# and 701 (47.5%) were men.
>s!k"s, Prevalence of cataract and prior cataract surgery
[S-#}C?~ As would be expected, the rate of any cataract increases
Ic^
(6 dramatically with age (Table 1). The weighted rate of any
[w-#
!X2y cataract in Victoria was 21.5% (95% CL 18.1, 24.9).
[z*1#lj S Although the rates varied somewhat between the three
@*uZ+$ strata, they were not significantly different as the 95% confidence
&h.?~Ri limits overlapped. The per cent of cataractous eyes
<[T{q
|* with best-corrected visual acuity of less than 6/12 was 12.5%
XF>!~D (65/520) for cortical cataract, 18% for nuclear cataract
t\PSB (97/534) and 14.4% (27/187) for PSC cataract. Cataract
pc
QkJF surgery also rose dramatically with age. The overall
Qs?p)3qp weighted rate of prior cataract surgery in Victoria was
hFan$W$ 3.79% (95% CL 2.97, 4.60) (Table 2).
mVN\ Risk factors for unoperated cataract
K@oyvJ$ Cases of cataract that had not been removed were classified
;>fM?ae5 as unoperated cataract. Risk factor analyses for unoperated
PBcb*7W cataract were not performed with the nursing home residents
meXwmO as information about risk factor exposure was not
l>hvWK[ ?I available for this cohort. The following factors were assessed
P)hGe3 in relation to unoperated cataract: age, sex, residence
yn20*ix{ (urban/rural), language spoken at home (a measure of ethnic
kw7E<a
F! integration), country of birth, parents’ country of birth (a
bj_/ measure of ethnicity), years since migration, education, use
e~9g~k]s of ophthalmic services, use of optometric services, private
eLV[U health insurance status, duration of distance glasses use,
(yeWArQ glaucoma, age-related maculopathy and employment status.
AM#s2.@ In this cross sectional study it was not possible to assess the
p;D
{?H/ level of visual acuity that would predict a patient’s having
r^ ' cataract surgery, as visual acuity data prior to cataract
B5R 7geC surgery were not available.
Z^%HDB9^ The significant risk factors for unoperated cataract in univariate
/)dyAX( analyses were related to: whether a participant had
,% .)mf ever seen an optometrist, seen an ophthalmologist or been
7h:EU7 diagnosed with glaucoma; and participants’ employment
9[
o$/x} status (currently employed) and age. These significant
5yj6MaqJ factors were placed in a backwards stepwise logistic regression
_fHj8-
s/ model. The factors that remained significantly related
uu>R)iTQ%S to unoperated cataract were whether participants had ever
/1bQ
RI^\ seen an ophthalmologist, seen an optometrist and been
)wdd"*hv diagnosed with glaucoma. None of the demographic factors
3a}c'$F>_' were associated with unoperated cataract in the multivariate
0bSnD|#I model.
(B?ZUXM, The per cent of participants with unoperated cataract
`_]Ul I_h who said that they were dissatisfied or very dissatisfied with
~0}d=d5g Operated and unoperated cataract in Australia 79
*/|<5X;xIA Table 1. Prevalence of any cataracta (excluding previous cataract surgery) by age, gender and cohort
?V(+Cc Age group Sex Urban Rural Nursing home Weighted total
"x0KiIoPk (years) (%) (%) (%)
zH#urF6< 40–49 Male 2.56 4.04 0.00 3.00 (1.91, 4.08)
[81q 0@ Female 2.61 1.70 0.00 2.36 (1.61, 3.10)
H7meI9L 50–59 Male 7.69 6.94 0.00 7.47 (5.80, 9.15)
S&D8Rao5 Female 6.67 7.56 0.00 6.92 (5.60, 8.24)
5ci1ce 60–69 Male 20.7 25.0 10.0 22.0 (18.1, 26.0)
@%fL*^yr;C Female 27.9 35.7 37.5 30.3 (26.0, 34.7)
1qm*#4x 70–79 Male 43.1 58.7 39.1 48.1 (41.2, 55.1)
IABF_GwF Female 58.6 66.2 55.6 61.0 (56.0, 65.9)
hZ"Sqm] 80–89 Male 74.0 89.3 92.0 79.3 (72.3, 86.3)
::-*~CH) Female 91.9 97.0 80.2 92.6 (86.4, 98.8)
6fCHd10! 90 + Male 100.0 100.0 75.0 98.8 (96.2, 100.0)
=j{Kxnv Female 100.0 100.0 93.8 98.6 (97.0, 100.0)
["<'fq;PJ Age-standardized
K}'?#a(aX= (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)
\: B))y?}d aCortical > 4/16, nuclear > standard 2, posterior subcapsular > 1 mm2
Q-1Xgw! their current vision was 30% (290/683), compared with 27%
%7?Z|'\ (26/95) of participants with prior cataract surgery (chisquared,
&VG 1 d.f. = 0.25, P = 0.62).
N:Ir63X*# Outcomes of cataract surgery
\m:('^\6o Two hundred and forty-nine eyes had undergone prior
cIP%t pTW. cataract surgery. Of these 249 operated eyes, 49 (20%) were
e{
*yV#Wl left aphakic, 6 (2.4%) had anterior chamber intraocular
$\M];S=CY lenses and 194 (78%) had posterior chamber intraocular
GR_caP lenses. The rate of capsulotomy in the eyes with intact
n9R0f9:* posterior capsules was 36% (73/202). Fifteen per cent of
4U u`1gtz eyes (17/114) with a clear posterior capsule had bestcorrected
)CgH|z:=b visual acuity of less than 6/12 compared with 43%
FPM l;0{ of eyes (6/14) with opaque capsules, and 15% of eyes
0sB[]E|7[s (11/73) with prior capsulotomies (chi-squared, 2 d.f. = 7.21,
sk
AF6n P = 0.027).
k+Z2)j" The percentage of eyes with best-corrected visual acuity
o/oLL w of 6/12 or better was 96% (302/314) for eyes without
LC\U6J't1 cataract, 88% (1417/1609) for eyes with prevalent cataract
,J:Ro N_: and 85% (211/249) for eyes with operated cataract (chisquared,
}]JHY P\ 2 d.f. = 22.3), P < 0.001). Twenty-seven of the
usC$NVdm operated eyes (11%) had visual acuities of less than 6/18
<y&&{*KW8m (moderate vision impairment) (Fig. 2). A cause of this
;|:R*(2 moderate visual impairment (but not the only cause) in four
c]/S<w< (15%) eyes was secondary to cataract surgery. Three of these
%.onO0}) four eyes had undergone intracapsular cataract extraction
''3I0X*! and the fourth eye had an opaque posterior capsule. No one
cv7:5P had bilateral vision impairment as a result of their cataract
T''<y S
surgery.
n=|% H'U DISCUSSION
T k@ ~w To our knowledge, this is the first paper to systematically
i83[': assess the prevalence of current cataract, previous cataract
0N$FIw2 surgery, predictors of unoperated cataract and the outcomes
OkfxX&n of cataract surgery in a population-based sample. The Visual
\Pcn D$L Impairment Project is unique in that the sampling frame and
U3Z-1G~*r high response rate have ensured that the study population is
<Y2$'ETD representative of Australians aged 40 years and over. Therefore,
5pK
_-:? these data can be used to plan age-related cataract
GR4DxlX services throughout Australia.
yc`*zLWh We found the rate of any cataract in those over the age
P,F
eF'J^ of 40 years to be 22%. Although relatively high, this rate is
b&dv("e
4 significantly less than was reported in a number of previous
+C[g>c}d studies,2,4,6 with the exception of the Casteldaccia Eye
b6p'%;Y/ Study.5 However, it is difficult to compare rates of cataract
QodWUbi'& between studies because of different methodologies and
?~!9\dek, cataract definitions employed in the various studies, as well
xu%eg] as the different age structures of the study populations.
tC5-^5[y Other studies have used less conservative definitions of
/,UnT(/k( cataract, thus leading to higher rates of cataract as defined.
~QDM
.5 In most large epidemiologic studies of cataract, visual acuity
0!7p5 has not been included in the definition of cataract.
Poa&htxe1 Therefore, the prevalence of cataract may not reflect the
`48Ql actual need for cataract surgery in the community.
}a.j~>rq 80 McCarty et al.
l;L_A@B< Table 2. Prevalence of previous cataract by age, gender and cohort
C4P<GtR9 Age group Gender Urban Rural Nursing home Weighted total
X8R`C0
(years) (%) (%) (%)
X2rKH$<g 40–49 Male 1.14 0.00 0.00 0.80 (0.00, 1.81)
u3GBAjPsIk Female 0.00 0.00 0.00 0.00 (
5j6`W?|q 50–59 Male 0.68 0.58 0.00 0.65 (0.13, 1.17)
|ns?c0rM Female 0.57 0.00 0.00 0.41 (0.00, 1.00)
M
+r!63T 60–69 Male 2.12 7.59 0.00 3.80 (1.41, 6.19)
?s3S$Ih Female 2.11 3.51 0.00 2.54 (1.81, 3.26)
2\QsF,@`YU 70–79 Male 8.22 9.85 8.70 8.75 (6.38, 11.1)
\7"|'fz Female 7.21 7.86 7.02 7.41 (5.36, 9.46)
#j=yQrJ
80–89 Male 25.0 30.0 14.3 26.2 (17.0, 35.4)
v{fcQb Female 27.9 25.6 18.3 26.7 (20.2, 33.3)
8.Y|I5l7G 90 + Male 0.00 16.7 66.7 9.19 (0.00, 21.5)
,^97Ks
; Female 58.3 100.0 26.9 63.1 (44.4, 81.8)
;%
B9mM#p~ Age-standardized
Vm>E F~ r (95% CL) Combined 3.31 (2.70, 3.93) 4.36 (2.67, 6.06) 2.26 (0.82, 3.70) 3.79 (2.97, 4.60)
fyA-*)oHv Figure 2. Visual acuity in eyes that had undergone cataract
nGkSS
_X surgery, n = 249. h, Presenting; j, best-corrected.
OmO#} k< Operated and unoperated cataract in Australia 81
Wi'}d6c The weighted prevalence of prior cataract surgery in the
X["xC3 i Visual Impairment Project (3.6%) was similar to the crude
d6YXITL)\> rate in the Beaver Dam Eye Study4 (3.1%), but less than the
h%Nd89// crude rate in the Blue Mountains Eye Study6 (6.0%).
A>1$?A8Q However, the age-standardized rate in the Blue Mountains
'=n?^EPE3 Eye Study (standardized to the age distribution of the urban
\`2'W1O Visual Impairment Project cohort) was found to be less than
MmR6V#@: the Visual Impairment Project (standardized rate = 1.36%,
r~j
[Qm"CJ 95% CL 1.25, 1.47). The incidence of cataract surgery in
7MLLx#U Australia has exceeded population growth.1 This is due,
?<TJ}("/ perhaps, to advances in surgical techniques and lens
JfIXv implants that have changed the risk–benefit ratio.
0lg$zi x( The Global Initiative for the Elimination of Avoidable
KBmO i Blindness, sponsored by the World Health Organization,
d?2ORr|m= states that cataract surgical services should be provided that
T8x)i\< ‘have a high success rate in terms of visual outcome and
'bi;Y1: improved quality of life’,17 although the ‘high success rate’ is
` 3qf}=Z` not defined. Population- and clinic-based studies conducted
A iM ukd, in the United States have demonstrated marked improvement
ctZ,qg*N in visual acuity following cataract surgery.18–20 We
iZ-R%- }B found that 85% of eyes that had undergone cataract extraction
?<EzILM had visual acuity of 6/12 or better. Previously, we have
IR6W'vA shown that participants with prevalent cataract in this
6 dRhK+| cohort are more likely to express dissatisfaction with their
g<W]NYm current vision than participants without cataract or participants
zjQ746<&)i with prior cataract surgery.21 In a national study in the
g
X!>ef United States, researchers found that the change in patients’
^ `y7JXI: ratings of their vision difficulties and satisfaction with their
|Ns4^2 vision after cataract surgery were more highly related to
1;ttwF>G7 their change in visual functioning score than to their change
Q)DEcx-|, in visual acuity.19 Furthermore, improvement in visual function
da7"Q{f+ has been shown to be associated with improvement in
"?NDN4l* overall quality of life.22
WigtTAh4 A recent review found that the incidence of visually
'Qy6m'esW significant posterior capsule opacification following
(p-q>@m cataract surgery to be greater than 25%.23 We found 36%
Qr$'Q7 capsulotomy in our population and that this was associated
fEHFlgN3Ap with visual acuity similar to that of eyes with a clear
Qn*l,Z]US capsule, but significantly better than that of eyes with an
7g\v (P opaque capsule.
}?s-$@$R A number of studies have shown that the demand and
>n"0>[:4 timing of cataract surgery vary according to visual acuity,
[ohLG_9 degree of handicap and socioeconomic factors.8–10,24,25 We
4YfM.~
6 have also shown previously that ophthalmologists are more
|[?O
tv likely to refer a patient for cataract surgery if the patient is
u#
76w74 employed and less likely to refer a nursing home resident.7
)p\`H;7*V4 In the Visual Impairment Project, we did not find that any
yYP_TuNa particular subgroup of the population was at greater risk of
& FhJ%JK having unoperated cataract. Universal access to health care
zZCl]cql in Australia may explain the fact that people without
!mlfG"FE Medicare are more likely to delay cataract operations in the
Bb/if:XS USA,8 but not having private health insurance is not associated
[c,V=:Cq with unoperated cataract in Australia.
Tb i?AJa} In summary, cataract is a significant public health problem
$${I[2R) in that one in four people in their 80s will have had cataract
7{m>W! surgery. The importance of age-related cataract surgery will
oco,sxT increase further with the ageing of the population: the
t"VT['8 number of people over age 60 years is expected to double in
*K/K97 the next 20 years. Cataract surgery services are well
50_[hC&C) accessed by the Victorian population and the visual outcomes
wn[)/*(,$( of cataract surgery have been shown to be very good.
Nf]?hfJ These data can be used to plan for age-related cataract
$s7U
|F,I surgical services in Australia in the future as the need for
Y$JVxly cataract extractions increases.
AG,><UP ACKNOWLEDGEMENTS
q;eb The Visual Impairment Project was funded in part by grants
rI$NNk'A from the Victorian Health Promotion Foundation, the
\IL)~5d National Health and Medical Research Council, the Ansell
_Raf7 W Ophthalmology Foundation, the Dorothy Edols Estate and
p<L7qwOii the Jack Brockhoff Foundation. Dr McCarty is the recipient
BM!ZdoKrKt of a Wagstaff Fellowship in Ophthalmology from the Royal
u>
{aF{ Victorian Eye and Ear Hospital.
D6VdgU| REFERENCES
p"0#G&- 1. Keeffe JE, Taylor HR. Cataract surgery in Australia 1985–94.
$ar^U Aust. N.Z. J. Ophthalmol. 1996; 24: 313–17.
|ke0G 2. Sperduto RD, Hiller R. The prevalence of nuclear, cortical,
(_pw\zk> and posterior subcapsular lens opacities in a general population
irlFB
#.. sample. Ophthalmology 1984; 91: 815–18.
tX^6R 3. Maraini G, Pasquini P, Sperduto RD et al. Distribution of lens
m"!SyN}&9? opacities in the Italian-American case–control study of agerelated
# xO PF9 cataract. Ophthalmology 1990; 97: 752–6.
EDnNS 4. Klein BEK, Klein R, Linton KLP. Prevalence of age-related
ZxtO.U2 lens opacities in a population. The Beaver Dam Eye Study.
ta?NO{*
Ophthalmology 1992; 99: 546–52.
()aCE^C 5. Guiffrè G, Giammanco R, Di Pace F, Ponte F. Casteldaccia eye
;.4y@?B study: prevalence of cataract in the adult and elderly population
T";evM66 of a Mediterranean town. Int. Ophthalmol. 1995; 18:
ST{Vi';} 363–71.
l,o'J%<% 6. Mitchell P, Cumming RG, Attebo K, Panchapakesan J.
iZNS? ^U Prevalence of cataract in Australia. The Blue Mountains Eye
:)lS9<Y} Study. Ophthalmology 1997; 104: 581–8.
6xDk3
7. Keeffe JE, McCarty CA, Chang WP, Steinberg EP, Taylor HR.
4M&$wi Relative importance of VA, patient concern and patient
$W7}Igx# lifestyle on referral for cataract surgery. Invest. Ophthalmol. Vis.
O|t>.<T? Sci. 1996; 37: S183.
u[**,.Ecg 8. Curbow B, Legro MW, Brenner MH. The influence of patientrelated
EK# 11@0% variables in the timing of cataract extraction. Am. J.
! ;>s .] Ophthalmol. 1993; 115: 614–22.
cvsH-uAp 9. Sletteberg OH, Høvding G, Bertelsen T. Do we operate too
o-bH3Jkb]& many cataracts? The referred cataract patients’ own appraisal
{@2+oOuYfN of their need for surgery. Acta Ophthalmol. Scand. 1995; 73:
/xUF@%rT 77–80.
E
3 % ~!ZC 10. Escarce JJ. Would eliminating differences in physician practice
t"B3?<?] style reduce geographic variations in cataract surgery rates?
JtO}i{A Med. Care 1993; 31: 1106–18.
CT'4. 11. Livingston PM, Carson CA, Stanislavsky YL, Lee SE, Guest
0J+WCm` CS, Taylor HR. Methods for a population-based study of eye
:fj>JF\[ disease: the Melbourne Visual Impairment Project. Ophthalmic
lo!pslqsn Epidemiol. 1994; 1: 139–48.
ZbC$Fk,,I& 12. Taylor HR, West SK. A simple system for the clinical grading
<}lah%4F of lens opacities. Lens Res. 1988; 5: 175–81.
_GkLspS
aU 82 McCarty et al.
BI%^7\HZ 13. Cochran WG. Sampling Techniques. New York: John Wiley &
I3 "6" Sons, 1977; 249–73.
n{N0S^h 14. Breslow NE, Day NE. Statistical Methods in Cancer Research. Volume
3:GwX4yW II – the Design and Analysis of Cohort Studies. Lyon: International
jOT/|k Agency for Research on Cancer; 1987; 52–61.
<-.@,HQ+ 15. Australian Bureau of Statistics. 1996 Census of Population and
]r#b:W\ Housing. Canberra: Australian Bureau of Statistics, 1997.
>/74u/& 16. Livingston PM, Lee SE, McCarty CA, Taylor HR. A comparison
/)kJ iV of participants with non-participants in a populationbased
<n,QSy#
epidemiologic study: the Melbourne Visual Impairment
Yeg<MrS4D Project. Ophthalmic Epidemiol. 1997; 4: 73–82.
`xx.,;S 17. Programme for the Prevention of Blindness. Global Initiative for the
[;{xiW4V] Elimination of Avoidable Blindness. Geneva: World Health
D]_6OlIE#' Organization, 1997.
{XIpHr 18. Applegate WB, Miller ST, Elam JT, Freeman JM, Wood TO,
cO]w*Hti Gettlefinger TC. Impact of cataract surgery with lens implantation
2pmj*Y3"8 on vision and physical function in elderly patients.
k6"(\d9o JAMA 1987; 257: 1064–6.
R +@|#! 19. Steinberg EP, Tielsch JM, Schein OD et al. National Study of
6~sU[thGW Cataract Surgery Outcomes. Variation in 4-month postoperative
8?8V; outcomes as reflected in multiple outcome measures.
{J)%6eL? Ophthalmology 1994; 101:1131–41.
s<LnUF1b 20. Klein BEK, Klein R, Moss SE. Change in visual acuity associated
~~|Iw=: with cataract surgery. The Beaver Dam Eye Study.
8Tg1 >q< Ophthalmology 1996; 103: 1727–31.
@?e~l:g})g 21. McCarty CA, Keeffe JE, Taylor HR. The need for cataract
~S<aIk0l surgery: projections based on lens opacity, visual acuity, and
uDND o personal concern. Br. J. Ophthalmol. 1999; 83: 62–5.
Pk;/4jt4 22. Brenner MH, Curbow B, Javitt JC, Legro MW, Sommer A.
j^#p#`m Vision change and quality of life in the elderly. Response to
EVLL,x.~:z cataract surgery and treatment of other ocular conditions.
7[P-;8)tq Arch. Ophthalmol. 1993; 111: 680–5.
9]Ue%%vM 23. Schaumberg DA, Dana MR, Christen WG, Glynn RJ. A
|hj!NhBe systematic overview of the incidence of posterior capsule
@:RoY vk$ opacification. Ophthalmology 1998; 105: 1213–21.
kh#QT_y 24. Mordue A, Parkin DW, Baxter C, Fawcett G, Stewart M.
%y9sC1
T Thresholds for treatment in cataract surgery. J. Public Health
'*L6@e#U Med. 1994; 16: 393–8.
Wk7E&?-:6 25. Norregaard JC, Bernth-Peterson P, Alonso J et al. Variations in
@Ol(:{< indications for cataract surgery in the United States, Denmark,
LDEc}XXb Canada, and Spain: results from the International Cataract
/0qbRk i Surgery Outcomes Study. Br. J. Ophthalmol. 1998; 82: 1107–11.