ABSTRACT
#Z
A
YP Purpose: To quantify the prevalence of cataract, the outcomes
j7&l&)5 of cataract surgery and the factors related to
e+wd>iiB unoperated cataract in Australia.
eORt
qX8* Methods: Participants were recruited from the Visual
tF|bxXsZ Impairment Project: a cluster, stratified sample of more than
bb{+ 5000 Victorians aged 40 years and over. At examination
D_Y;N3E/rS sites interviews, clinical examinations and lens photography
ry'(mM were performed. Cataract was defined in participants who
4rm/+Zes had: had previous cataract surgery, cortical cataract greater
k
bY@Y,:w than 4/16, nuclear greater than Wilmer standard 2, or
@lwqkJ posterior subcapsular greater than 1 mm2.
Fr~xN!
Results: The participant group comprised 3271 Melbourne
V;"'!dVX residents, 403 Melbourne nursing home residents and 1473
Dng^4VRd rural residents.The weighted rate of any cataract in Victoria
U&6f}=vC was 21.5%. The overall weighted rate of prior cataract
QU t!fF@t surgery was 3.79%. Two hundred and forty-nine eyes had
J?&9ofj& had prior cataract surgery. Of these 249 procedures, 49
$)U
RY~;i (20%) were aphakic, 6 (2.4%) had anterior chamber
4T:ZEvdzf intraocular lenses and 194 (78%) had posterior chamber
?g'l/xuRe intraocular lenses.Two hundred and eleven of these operated
<t8}) eyes (85%) had best-corrected visual acuity of 6/12 or
V|7 cdX#H better, the legal requirement for a driver’s license.Twentyseven
vQ;Z 0_ (11%) had visual acuity of less than 6/18 (moderate
u>BR WN vision impairment). Complications of cataract surgery
x-[l`k.V caused reduced vision in four of the 27 eyes (15%), or 1.9%
/O9z-!Jz of operated eyes. Three of these four eyes had undergone
*`kh} intracapsular cataract extraction and the fourth eye had an
){v nmJJ% opaque posterior capsule. No one had bilateral vision
Qi9SN00F. impairment as a result of cataract surgery. Surprisingly, no
qg_=5s particular demographic factors (such as age, gender, rural
MD +Q_ residence, occupation, employment status, health insurance
;aSEv"iWX status, ethnicity) were related to the presence of unoperated
bS*9eX=K cataract.
T!8,R{V]4 Conclusions: Although the overall prevalence of cataract is
8IO4>CMkv quite high, no particular subgroup is systematically underserviced
_T1|_9b in terms of cataract surgery. Overall, the results of
YQ]W<0( cataract surgery are very good, with the majority of eyes
=m UtBD.; achieving driving vision following cataract extraction.
<%!EI@N Key words: cataract extraction, health planning, health
Gx!Y
4Q}- services accessibility, prevalence
l2i[wc"9 INTRODUCTION
@I9A"4Im Cataract is the leading cause of blindness worldwide and, in
y6fYNB Australia, cataract extractions account for the majority of all
G22u+ua ophthalmic procedures.1 Over the period 1985–94, the rate
`j9 ;9^ of cataract surgery in Australia was twice as high as would be
+Y-Gp4" expected from the growth in the elderly population.1
G@s
rQum( Although there have been a number of studies reporting
`Ps&N^[ the prevalence of cataract in various populations,2–6 there is
5y0N }} little information about determinants of cataract surgery in
vr"O9L
w the population. A previous survey of Australian ophthalmologists
<m'W{n%Pp showed that patient concern and lifestyle, rather
kZ$2Uss than visual acuity itself, are the primary factors for referral
c~SR@ZU for cataract surgery.7 This supports prior research which has
e w?4; shown that visual acuity is not a strong predictor of need for
Q\rf J|| cataract surgery.8,9 Elsewhere, socioeconomic status has
kntYj}F( been shown to be related to cataract surgery rates.10
}p5_JXBV To appropriately plan health care services, information is
g8kS}7/ needed about the prevalence of age-related cataract in the
VkFMr8@| community as well as the factors associated with cataract
/*P) C'_M surgery. The purpose of this study is to quantify the prevalence
y*=sboX
of any cataract in Australia, to describe the factors
S#kYPe related to unoperated cataract in the community and to
G>=Fdt7Oc describe the visual outcomes of cataract surgery.
# ~Doz7~ METHODS
>v2/0>U Study population
'Fy"|M;2 Details about the study methodology for the Visual
AXF
1{ Impairment Project have been published previously.11
/yHjds Briefly, cluster sampling within three strata was employed to
{xx}xib3 recruit subjects aged 40 years and over to participate.
eAmI~oku Within the Melbourne Statistical Division, nine pairs of
Unvl~lm6 census collector districts were randomly selected. Fourteen
BmKf%:l} nursing homes within a 5 km radius of these nine test sites
-0UR%R7q were randomly chosen to recruit nursing home residents.
!B 4z U:d Clinical and Experimental Ophthalmology (2000) 28, 77–82
,Kl:4 Tv Original Article
! ui Operated and unoperated cataract in Australia
,`JYFh M Catherine A McCarty PhD, MPH, Mukesh B Nanjan PhD, Hugh R Taylor MD
rRg,{:;A Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
hw,nA2w\ n Correspondence: Dr Cathy McCarty MPH, Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, 32 Gisborne Street, East Melbourne,
s3eS` rK- Victoria 3002, Australia. Email:
cathy@cera.unimelb.edu.au :`e#I/, 78 McCarty et al.
Kf1J;*i|\ Finally, four pairs of census collector districts in four rural
9j|v
D Victorian communities were randomly selected to recruit rural
q[_qZ residents. A household census was conducted to identify
QuqznYSY{ eligible residents aged 40 years and over who had been a
g!R7CRt% resident at that address for at least 6 months. At the time of
0W(mx-[H/ the household census, basic information about age, sex,
+9w[/n ^,G country of birth, language spoken at home, education, use of
9T;4aP>6j# corrective spectacles and use of eye care services was collected.
`*Yw-HL Eligible residents were then invited to attend a local
5X20/+aT examination site for a more detailed interview and examination.
)[ A-d(y= The study protocol was approved by the Royal Victorian
&cL1
EQ( Eye and Ear Hospital Human Research Ethics Committee.
>x{("``D0y Assessment of cataract
cc|W1,q A standardized ophthalmic examination was performed after
>G:Q/3jh pupil dilatation with one drop of 10% phenylephrine
U?#wWbE1 hydrochloride. Lens opacities were graded clinically at the
moM?aYm time of the examination and subsequently from photos using
)O]6dd the Wilmer cataract photo-grading system.12 Cortical and
eR$@Q
posterior subcapsular (PSC) opacities were assessed on
:j]1wp+ retroillumination and measured as the proportion (in 1/16)
5EFt0?G of pupil circumference occupied by opacity. For this analysis,
/K#k_k cortical cataract was defined as 4/16 or greater opacity,
lI<jYd
0fZ PSC cataract was defined as opacity equal to or greater than
X:oOp=y]| 1 mm2 and nuclear cataract was defined as opacity equal to
C|V7ZL>W or greater than Wilmer standard 2,12 independent of visual
`,qft[1 acuity. Examples of the minimum opacities defined as cortical,
{y9G
" nuclear and PSC cataract are presented in Figure 1.
k,:W]KD Bilateral congenital cataracts or cataracts secondary to
&DLWlMGq intraocular inflammation or trauma were excluded from the
xDo0bR(
analysis. Two cases of bilateral secondary cataract and eight
3`bQ0-D; cases of bilateral congenital cataract were excluded from the
:W.H#@'( analyses.
.nPOjwEx&Y A Topcon® SL5 photo slit-lamp (Topcon America Corp.,
XQo\27Fo Paramus, NJ, USA) with a 0.1 mm slit beam of 9.0 mm in
=W~7fs height set to an incident angle of 30° was used for examinations.
i#'K7XM2 Ektachrome® 200 ASA colour slide film (Eastman
], lLDUZ\ Kodak Company, Rochester, NY, USA) was used to photograph
Tqt-
zX|> the nuclear opacities. The cortical opacities were
D0Dz@25- photographed with an Oxford® retroillumination camera
dKzG,/1W[m (Marcher Enterprises Ltd, Hereford, UK) and T-MAX® 400
S%iK); film (Eastman Kodak). Photographs were graded separately
EtcT:k?y by two research assistants and discrepancies were adjudicated
e$[O J<t by an independent reviewer. Any discrepancies
wW%b~JX between the clinical grades and the photograph grades were
0>28o. resolved. Except in cases where photographs were missing,
GHsDZ(d3. the photograph grades were used in the analyses. Photograph
\lbH
grades were available for 4301 (84%) for cortical
|5^
iqW cataract, 4147 (81%) for nuclear cataract and 4303 (84%)
Gdo
w[x for PSC cataract. Cataract status was classified according to
s ~Eo]e the severity of the opacity in the worse eye.
``/L18 Assessment of risk factors
jj{:=lZB A standardized questionnaire was used to obtain information
In?rQiD9 about education, employment and ethnic background.11
WsHDIp Specific information was elicited on the occurrence, duration
%r^tZ ;;l and treatment of a number of medical conditions,
aT,W
XW* including ocular trauma, arthritis, diabetes, gout, hypertension
K*:=d}^ and mental illness. Information about the use, dose and
ntIR #fB
duration of tobacco, alcohol, analgesics and steriods were
~cm4e>o collected, and a food frequency questionnaire was used to
uH89oA/H determine current consumption of dietary sources of antioxidants
2hHRitt36 and use of vitamin supplements.
tR!C8:u Data management and statistical analysis
)<QX2~m< Data were collected either by direct computer entry with a
Yi9Y`~J questionnaire programmed in Paradox© (Carel Corporation,
XpANaqH\ Ottawa, Canada) with internal consistency checks, or
PJK:LZw on self-coding forms. Open-ended responses were coded at
}XUL\6 U a later time. Data that were entered on the self-coded forms
"}X+vd`` were entered into a computer with double data entry and
.s\lfBo9 reconciliation of any inconsistencies. Data range and consistency
&<><4MQ checks were performed on the entire data set.
_n:RA)4* SAS© version 6.1 (SAS Institute, Cary, North Carolina) was
OG{*:1EP employed for statistical analyses.
p-j6H Ninety-five per cent confidence limits around the agespecific
-3ePCAtXbe rates were calculated according to Cochran13 to
>$ZhhM/} J account for the effect of the cluster sampling. Ninety-five
+s<6eHpm per cent confidence limits around age-standardized rates
reR@@O were calculated according to Breslow and Day.14 The strataspecific
6D| F1UFU data were weighted according to the 1996
Fug4u?-n Australian Bureau of Statistics census data15 to reflect the
&B5&:ib1
D cataract prevalence in the entire Victorian population.
bGwOhd<. Univariate analyses with Student’s t-tests and chi-squared
zHKP$k8 tests were first employed to evaluate risk factors for unoperated
5BA:^4zr? cataract. Any factors with P < 0.10 were then fitted
a(~X into a backwards stepwise logistic regression model. For the
Hya.OW{ Figure 1. Minimum levels of cortical (a), nuclear (b), and posterior subcapsular (c) cataract.
:^W}$7$T final multivariate models, P < 0.05 was considered statistically
.RmFYV0, significant. Design effect was assessed through the use
Y;R,ph.a of cluster-specific models and multivariate models. The
n><ad*|MX design effect was assumed to be additive and an adjustment
+8xT}mX made in the variance by adding the variance associated with
<b'*GB
w$ the design effect prior to constructing the 95% confidence
Vs TgK limits.
8N)Lck2PR RESULTS
G(?1 Urxi Study population
bp/l~h.7W A total of 3271 (83%) of the Melbourne residents, 403
xKUWj<+/ (90%) Melbourne nursing home residents, and 1473 (92%)
;1yF[<a rural residents participated. In general, non-participants did
!\| not differ from participants.16 The study population was
[f\Jcjc representative of the Victorian population and Australia as
<V)z{uK a whole.
.h4NG4FIF The Melbourne residents ranged in age from 40 to
X*MK(aV3 98 years (mean = 59) and 1511 (46%) were male. The
Z79 6;qk Melbourne nursing home residents ranged in age from 46 to
>VZxDJ$R 101 years (mean = 82) and 85 (21%) were men. The rural
W{Je)N residents ranged in age from 40 to 103 years (mean = 60)
F3vywN1$, and 701 (47.5%) were men.
OmkJP Prevalence of cataract and prior cataract surgery
wZ0bD&B
As would be expected, the rate of any cataract increases
wEq&O|Vj dramatically with age (Table 1). The weighted rate of any
SFh<>J^ 0a cataract in Victoria was 21.5% (95% CL 18.1, 24.9).
(;=|2N>7 Although the rates varied somewhat between the three
ewT
K2 strata, they were not significantly different as the 95% confidence
@f"[*7Q`/ limits overlapped. The per cent of cataractous eyes
1p5'.~J+Q with best-corrected visual acuity of less than 6/12 was 12.5%
fe<7D\Sp@ (65/520) for cortical cataract, 18% for nuclear cataract
4$, W\d (97/534) and 14.4% (27/187) for PSC cataract. Cataract
LN(\B:wAY surgery also rose dramatically with age. The overall
FZ%h7Oe weighted rate of prior cataract surgery in Victoria was
PX?%}~
v 3.79% (95% CL 2.97, 4.60) (Table 2).
CAvi P61T Risk factors for unoperated cataract
LEjq<t1& Cases of cataract that had not been removed were classified
JFc,f as unoperated cataract. Risk factor analyses for unoperated
"oiN8#Hf cataract were not performed with the nursing home residents
?fP3R':s as information about risk factor exposure was not
^ )"Il available for this cohort. The following factors were assessed
u4T$ in relation to unoperated cataract: age, sex, residence
I6;6x (urban/rural), language spoken at home (a measure of ethnic
%{IgY{X integration), country of birth, parents’ country of birth (a
:zo5`[P measure of ethnicity), years since migration, education, use
V:j^!* of ophthalmic services, use of optometric services, private
XM+.Hel health insurance status, duration of distance glasses use,
0+1!-Wo glaucoma, age-related maculopathy and employment status.
VI9rezZ* In this cross sectional study it was not possible to assess the
:4 z\Q] level of visual acuity that would predict a patient’s having
OAiW8BAe cataract surgery, as visual acuity data prior to cataract
_kRc"MaB surgery were not available.
JW><&hY$" The significant risk factors for unoperated cataract in univariate
NTX0vQG analyses were related to: whether a participant had
yU/?4/G! ever seen an optometrist, seen an ophthalmologist or been
{ Mb<onW diagnosed with glaucoma; and participants’ employment
@8`I!fZ status (currently employed) and age. These significant
MC,Qv9
m factors were placed in a backwards stepwise logistic regression
b'SP,}s5" model. The factors that remained significantly related
zRLJ|ejMP to unoperated cataract were whether participants had ever
w (`g)` seen an ophthalmologist, seen an optometrist and been
*XWu) >*o diagnosed with glaucoma. None of the demographic factors
#mUQ@X@K were associated with unoperated cataract in the multivariate
#6#n4`%ER model.
@}Ry7H0O The per cent of participants with unoperated cataract
xc@$z*w who said that they were dissatisfied or very dissatisfied with
NTZ3Np` Operated and unoperated cataract in Australia 79
F~E)w5?\O Table 1. Prevalence of any cataracta (excluding previous cataract surgery) by age, gender and cohort
'xai5X Age group Sex Urban Rural Nursing home Weighted total
%=2sz>M+ (years) (%) (%) (%)
UE5,Ml~X 40–49 Male 2.56 4.04 0.00 3.00 (1.91, 4.08)
YwY?tOxBe Female 2.61 1.70 0.00 2.36 (1.61, 3.10)
/@
g 8MUq7 50–59 Male 7.69 6.94 0.00 7.47 (5.80, 9.15)
6r
mx{Bt Female 6.67 7.56 0.00 6.92 (5.60, 8.24)
a""9%./B 60–69 Male 20.7 25.0 10.0 22.0 (18.1, 26.0)
e~)4v Female 27.9 35.7 37.5 30.3 (26.0, 34.7)
}oG6XI9 70–79 Male 43.1 58.7 39.1 48.1 (41.2, 55.1)
W[`ybGR< Female 58.6 66.2 55.6 61.0 (56.0, 65.9)
zi
O(`"v 80–89 Male 74.0 89.3 92.0 79.3 (72.3, 86.3)
E>*b,^J7g Female 91.9 97.0 80.2 92.6 (86.4, 98.8)
<bCB-lG*Kb 90 + Male 100.0 100.0 75.0 98.8 (96.2, 100.0)
[{xY3WS Female 100.0 100.0 93.8 98.6 (97.0, 100.0)
# Dgkl Age-standardized
7u^wO< (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)
GadY#]}( aCortical > 4/16, nuclear > standard 2, posterior subcapsular > 1 mm2
b9i_\ their current vision was 30% (290/683), compared with 27%
a}VR>!b (26/95) of participants with prior cataract surgery (chisquared,
.L#4#IO 1 d.f. = 0.25, P = 0.62).
RB""(< Outcomes of cataract surgery
<)O#Y76s Two hundred and forty-nine eyes had undergone prior
75
R4[C6T cataract surgery. Of these 249 operated eyes, 49 (20%) were
8aRmHy"9l left aphakic, 6 (2.4%) had anterior chamber intraocular
lc
fAb@}2 lenses and 194 (78%) had posterior chamber intraocular
Z(4/;v <CT lenses. The rate of capsulotomy in the eyes with intact
GpXf).a@ posterior capsules was 36% (73/202). Fifteen per cent of
P*?2+. eyes (17/114) with a clear posterior capsule had bestcorrected
E)I&? <g visual acuity of less than 6/12 compared with 43%
~KGE(o4p of eyes (6/14) with opaque capsules, and 15% of eyes
Wx;%W"a (11/73) with prior capsulotomies (chi-squared, 2 d.f. = 7.21,
:nnch?J_ P = 0.027).
L=!h`k The percentage of eyes with best-corrected visual acuity
"AMw o(Yi of 6/12 or better was 96% (302/314) for eyes without
#|:q"l9 cataract, 88% (1417/1609) for eyes with prevalent cataract
BgCEv"G5 and 85% (211/249) for eyes with operated cataract (chisquared,
FRPd
fo37 2 d.f. = 22.3), P < 0.001). Twenty-seven of the
1,Pg^Xu operated eyes (11%) had visual acuities of less than 6/18
#gf0*:p (moderate vision impairment) (Fig. 2). A cause of this
u,YmCEd_V moderate visual impairment (but not the only cause) in four
$'*{&/@ (15%) eyes was secondary to cataract surgery. Three of these
98zJ?NaD& four eyes had undergone intracapsular cataract extraction
e*D,2>o and the fourth eye had an opaque posterior capsule. No one
tg/!=g had bilateral vision impairment as a result of their cataract
6_9@s*=d> surgery.
ky]L`w DISCUSSION
!,7)ZW?*8 To our knowledge, this is the first paper to systematically
h;cw=G assess the prevalence of current cataract, previous cataract
^\VVx:] surgery, predictors of unoperated cataract and the outcomes
G-o6~"J\ of cataract surgery in a population-based sample. The Visual
K7q R Impairment Project is unique in that the sampling frame and
%|2x7@&s high response rate have ensured that the study population is
{FN4BC`3+ representative of Australians aged 40 years and over. Therefore,
~/K'n
these data can be used to plan age-related cataract
;t.)A3 PL services throughout Australia.
KC<K*UHPAH We found the rate of any cataract in those over the age
[A;0IjKam of 40 years to be 22%. Although relatively high, this rate is
NeewV=[% significantly less than was reported in a number of previous
[RDY(}P% studies,2,4,6 with the exception of the Casteldaccia Eye
weOga\ Study.5 However, it is difficult to compare rates of cataract
W>u$x=<T between studies because of different methodologies and
3XUie;*` cataract definitions employed in the various studies, as well
Fdx4jc13w as the different age structures of the study populations.
CT=5V@_u\ Other studies have used less conservative definitions of
8tT/w5 cataract, thus leading to higher rates of cataract as defined.
/ EVXkf0 In most large epidemiologic studies of cataract, visual acuity
C8 $KVZ has not been included in the definition of cataract.
~.S/<:`U Therefore, the prevalence of cataract may not reflect the
- l0X]&Ex actual need for cataract surgery in the community.
cw~-%%/ 80 McCarty et al.
2<_|1%C Table 2. Prevalence of previous cataract by age, gender and cohort
gYw=Z_z Age group Gender Urban Rural Nursing home Weighted total
X'7MW?
q@ (years) (%) (%) (%)
3+vMi[YO 40–49 Male 1.14 0.00 0.00 0.80 (0.00, 1.81)
<ZoMKUuB Female 0.00 0.00 0.00 0.00 (
}~ga86:n0 50–59 Male 0.68 0.58 0.00 0.65 (0.13, 1.17)
^QTkre Female 0.57 0.00 0.00 0.41 (0.00, 1.00)
Lyjp 60–69 Male 2.12 7.59 0.00 3.80 (1.41, 6.19)
!$,e)89 Female 2.11 3.51 0.00 2.54 (1.81, 3.26)
ENZYrWl
70–79 Male 8.22 9.85 8.70 8.75 (6.38, 11.1)
>% E=
l Female 7.21 7.86 7.02 7.41 (5.36, 9.46)
KC-@2,c9V 80–89 Male 25.0 30.0 14.3 26.2 (17.0, 35.4)
YD;"_yH Female 27.9 25.6 18.3 26.7 (20.2, 33.3)
J['?ud}@ 90 + Male 0.00 16.7 66.7 9.19 (0.00, 21.5)
q{Gf@ Female 58.3 100.0 26.9 63.1 (44.4, 81.8)
S\A9r!2 Age-standardized
=K6{AmG$ (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)
2D{`AJ Figure 2. Visual acuity in eyes that had undergone cataract
,k6V?{ZA surgery, n = 249. h, Presenting; j, best-corrected.
l]geQl:7`r Operated and unoperated cataract in Australia 81
lT F#efcW The weighted prevalence of prior cataract surgery in the
od]1:8OF Visual Impairment Project (3.6%) was similar to the crude
O['5/:- rate in the Beaver Dam Eye Study4 (3.1%), but less than the
*> 7Zc crude rate in the Blue Mountains Eye Study6 (6.0%).
h1Q rFPQnu However, the age-standardized rate in the Blue Mountains
Vg1MA Eye Study (standardized to the age distribution of the urban
0"xD>ue& Visual Impairment Project cohort) was found to be less than
]*yUb-xY the Visual Impairment Project (standardized rate = 1.36%,
Vg8c}>7 95% CL 1.25, 1.47). The incidence of cataract surgery in
9rM6kLD Australia has exceeded population growth.1 This is due,
xw~&OF& perhaps, to advances in surgical techniques and lens
:LX
(9f implants that have changed the risk–benefit ratio.
,
Y cF~ The Global Initiative for the Elimination of Avoidable
{{e+t8J?? Blindness, sponsored by the World Health Organization,
sn:wLc/GAd states that cataract surgical services should be provided that
OA8iTn ‘have a high success rate in terms of visual outcome and
WRfhxl improved quality of life’,17 although the ‘high success rate’ is
./E<v not defined. Population- and clinic-based studies conducted
GF^?#Jh in the United States have demonstrated marked improvement
_6{XqvWqb in visual acuity following cataract surgery.18–20 We
qb7ur; found that 85% of eyes that had undergone cataract extraction
,L9ioYbp had visual acuity of 6/12 or better. Previously, we have
Vh5Z'4N shown that participants with prevalent cataract in this
;\)N7SJ cohort are more likely to express dissatisfaction with their
/&g~*AL current vision than participants without cataract or participants
"o>gX'm* with prior cataract surgery.21 In a national study in the
=/L
;}m)7 United States, researchers found that the change in patients’
zkmfu~_) ratings of their vision difficulties and satisfaction with their
! )PV-[2 vision after cataract surgery were more highly related to
L
Ke~ their change in visual functioning score than to their change
*HXx;: in visual acuity.19 Furthermore, improvement in visual function
xO2CgqEb has been shown to be associated with improvement in
23~KzC overall quality of life.22
R`!
'c(V A recent review found that the incidence of visually
JN:EcVuy significant posterior capsule opacification following
55]E<2't cataract surgery to be greater than 25%.23 We found 36%
Y; OqdO capsulotomy in our population and that this was associated
}Gg:y? with visual acuity similar to that of eyes with a clear
yi$ Jk}w capsule, but significantly better than that of eyes with an
|B/A)(c
yV opaque capsule.
?wQaM3 |^: A number of studies have shown that the demand and
[W{WfJ-HwG timing of cataract surgery vary according to visual acuity,
( :ObxJ* degree of handicap and socioeconomic factors.8–10,24,25 We
`oUuAL have also shown previously that ophthalmologists are more
{Mx3G*hr likely to refer a patient for cataract surgery if the patient is
-^+!:0'; employed and less likely to refer a nursing home resident.7
1hnw+T<<W In the Visual Impairment Project, we did not find that any
Zr
U9oy&!C particular subgroup of the population was at greater risk of
&mJ
+#vT having unoperated cataract. Universal access to health care
WC<K(PP in Australia may explain the fact that people without
a2tRmil Medicare are more likely to delay cataract operations in the
lyY
i2& % USA,8 but not having private health insurance is not associated
"UDV4<|^k with unoperated cataract in Australia.
;)nV In summary, cataract is a significant public health problem
ollk {N in that one in four people in their 80s will have had cataract
A:-r2;xB surgery. The importance of age-related cataract surgery will
L 2k?Pl increase further with the ageing of the population: the
<B%s9Zy number of people over age 60 years is expected to double in
xOAA1# the next 20 years. Cataract surgery services are well
uO,9h0y0W accessed by the Victorian population and the visual outcomes
50l!f7 of cataract surgery have been shown to be very good.
d|RqS`h
] These data can be used to plan for age-related cataract
6bXR?0$*M. surgical services in Australia in the future as the need for
;&N=t64" cataract extractions increases.
f,_EPh> ACKNOWLEDGEMENTS
<*4BT}r,^2 The Visual Impairment Project was funded in part by grants
`$5
QTte from the Victorian Health Promotion Foundation, the
v==b.
2= National Health and Medical Research Council, the Ansell
jLZ^EM- Ophthalmology Foundation, the Dorothy Edols Estate and
!lk
-MN. the Jack Brockhoff Foundation. Dr McCarty is the recipient
".Q``d&X of a Wagstaff Fellowship in Ophthalmology from the Royal
i6@c@n Victorian Eye and Ear Hospital.
RrG5`2 REFERENCES
$yA>j (k4 1. Keeffe JE, Taylor HR. Cataract surgery in Australia 1985–94.
PS=N]e7k' Aust. N.Z. J. Ophthalmol. 1996; 24: 313–17.
VoTnm
2. Sperduto RD, Hiller R. The prevalence of nuclear, cortical,
ZHWxU and posterior subcapsular lens opacities in a general population
yDil sample. Ophthalmology 1984; 91: 815–18.
aGR!T{` 3. Maraini G, Pasquini P, Sperduto RD et al. Distribution of lens
&I|\AG"X} opacities in the Italian-American case–control study of agerelated
,@#))2<RK cataract. Ophthalmology 1990; 97: 752–6.
m/T3Um 4. Klein BEK, Klein R, Linton KLP. Prevalence of age-related
lI<Q=gd lens opacities in a population. The Beaver Dam Eye Study.
m);0sb Ophthalmology 1992; 99: 546–52.
!d)Vr5x 5. Guiffrè G, Giammanco R, Di Pace F, Ponte F. Casteldaccia eye
1_of;=9V study: prevalence of cataract in the adult and elderly population
k"z ~> of a Mediterranean town. Int. Ophthalmol. 1995; 18:
iaAj|: 363–71.
5x=aJl;G 6. Mitchell P, Cumming RG, Attebo K, Panchapakesan J.
s
IE2a0+ Prevalence of cataract in Australia. The Blue Mountains Eye
=,])xzG% Study. Ophthalmology 1997; 104: 581–8.
KqD]GS#( 7. Keeffe JE, McCarty CA, Chang WP, Steinberg EP, Taylor HR.
g"dq;H Relative importance of VA, patient concern and patient
_-M27^\vV lifestyle on referral for cataract surgery. Invest. Ophthalmol. Vis.
5OR2\h!XZt Sci. 1996; 37: S183.
,Hzz:ce 8. Curbow B, Legro MW, Brenner MH. The influence of patientrelated
,'nd~{pX"( variables in the timing of cataract extraction. Am. J.
VbG#)>"F Ophthalmol. 1993; 115: 614–22.
n?[JPG2X 9. Sletteberg OH, Høvding G, Bertelsen T. Do we operate too
ev'` K=n8 many cataracts? The referred cataract patients’ own appraisal
X>la!}sV of their need for surgery. Acta Ophthalmol. Scand. 1995; 73:
t4P`#,:8 77–80.
W0 n?S
" 10. Escarce JJ. Would eliminating differences in physician practice
kF@Z4MB}yr style reduce geographic variations in cataract surgery rates?
d$H Med. Care 1993; 31: 1106–18.
^ 5D%)@~ 11. Livingston PM, Carson CA, Stanislavsky YL, Lee SE, Guest
JqmxS*_P CS, Taylor HR. Methods for a population-based study of eye
HVHd@#pDZ disease: the Melbourne Visual Impairment Project. Ophthalmic
_u{z$; Epidemiol. 1994; 1: 139–48.
zzH^xxg 12. Taylor HR, West SK. A simple system for the clinical grading
v:1DNR4 of lens opacities. Lens Res. 1988; 5: 175–81.
CiNOGSlDj 82 McCarty et al.
P{K;vEp 13. Cochran WG. Sampling Techniques. New York: John Wiley &
GyZpdp! Sons, 1977; 249–73.
;xl0J*r 14. Breslow NE, Day NE. Statistical Methods in Cancer Research. Volume
ZamOYkRX II – the Design and Analysis of Cohort Studies. Lyon: International
cFZcBiw Agency for Research on Cancer; 1987; 52–61.
ogvB{R
15. Australian Bureau of Statistics. 1996 Census of Population and
YZk.{#^ c Housing. Canberra: Australian Bureau of Statistics, 1997.
=G9I7Y@ 16. Livingston PM, Lee SE, McCarty CA, Taylor HR. A comparison
p>l:^-N;f of participants with non-participants in a populationbased
{ew;
/; epidemiologic study: the Melbourne Visual Impairment
#I"s{*
Project. Ophthalmic Epidemiol. 1997; 4: 73–82.
L"tzUYxg 17. Programme for the Prevention of Blindness. Global Initiative for the
|[Rlg`TQ;* Elimination of Avoidable Blindness. Geneva: World Health
&"?S0S>r! Organization, 1997.
H:F'5Zt 18. Applegate WB, Miller ST, Elam JT, Freeman JM, Wood TO,
%XBMi~ Gettlefinger TC. Impact of cataract surgery with lens implantation
Lb,wn{ on vision and physical function in elderly patients.
QnA~,z/.w JAMA 1987; 257: 1064–6.
;Rljx3!N 19. Steinberg EP, Tielsch JM, Schein OD et al. National Study of
\2^o,1r/ Cataract Surgery Outcomes. Variation in 4-month postoperative
SU5O+;{`' outcomes as reflected in multiple outcome measures.
5HaI$>h6 Ophthalmology 1994; 101:1131–41.
c`@";+|r 20. Klein BEK, Klein R, Moss SE. Change in visual acuity associated
a D+4uGN with cataract surgery. The Beaver Dam Eye Study.
O.DO,]Uh Ophthalmology 1996; 103: 1727–31.
neQ~h4U" 21. McCarty CA, Keeffe JE, Taylor HR. The need for cataract
akFT 0@9 surgery: projections based on lens opacity, visual acuity, and
#U(kK(uO personal concern. Br. J. Ophthalmol. 1999; 83: 62–5.
^
-4~pDv^ 22. Brenner MH, Curbow B, Javitt JC, Legro MW, Sommer A.
A5T&i] Vision change and quality of life in the elderly. Response to
X'88
W- cataract surgery and treatment of other ocular conditions.
<aLS4 Arch. Ophthalmol. 1993; 111: 680–5.
.I?~R:(Ig 23. Schaumberg DA, Dana MR, Christen WG, Glynn RJ. A
q
BIekQT systematic overview of the incidence of posterior capsule
fx-8mf3 opacification. Ophthalmology 1998; 105: 1213–21.
f`)*bx 24. Mordue A, Parkin DW, Baxter C, Fawcett G, Stewart M.
J&iSS9c Thresholds for treatment in cataract surgery. J. Public Health
l8khu)\n4R Med. 1994; 16: 393–8.
/xSFW7d1 25. Norregaard JC, Bernth-Peterson P, Alonso J et al. Variations in
L~%7
=]m indications for cataract surgery in the United States, Denmark,
@qpj0i+>* Canada, and Spain: results from the International Cataract
ez5J+ Surgery Outcomes Study. Br. J. Ophthalmol. 1998; 82: 1107–11.