ABSTRACT
1sL#XB$@N Purpose: To quantify the prevalence of cataract, the outcomes
J`T1 88 of cataract surgery and the factors related to
AnV\{A^ unoperated cataract in Australia.
IR (6 Methods: Participants were recruited from the Visual
=qY!<DB[L Impairment Project: a cluster, stratified sample of more than
PQ`p:=~>:i 5000 Victorians aged 40 years and over. At examination
TO.71x| sites interviews, clinical examinations and lens photography
v$R+5_@[l were performed. Cataract was defined in participants who
xkIRI1*! had: had previous cataract surgery, cortical cataract greater
1]HEwTT/1_ than 4/16, nuclear greater than Wilmer standard 2, or
$EjM)
posterior subcapsular greater than 1 mm2.
=
Rl?. +uE Results: The participant group comprised 3271 Melbourne
;-=Q6Ms8 residents, 403 Melbourne nursing home residents and 1473
tZS-e6*S rural residents.The weighted rate of any cataract in Victoria
j rX.e was 21.5%. The overall weighted rate of prior cataract
sd;J(<Ofh surgery was 3.79%. Two hundred and forty-nine eyes had
6#S}EaWf had prior cataract surgery. Of these 249 procedures, 49
2s{P
E (20%) were aphakic, 6 (2.4%) had anterior chamber
MT
ZbRi6z intraocular lenses and 194 (78%) had posterior chamber
hlPZTr=a intraocular lenses.Two hundred and eleven of these operated
U$[C>~ r eyes (85%) had best-corrected visual acuity of 6/12 or
$vNz^!zgV better, the legal requirement for a driver’s license.Twentyseven
.\kcWeC\ (11%) had visual acuity of less than 6/18 (moderate
h_K(8{1 vision impairment). Complications of cataract surgery
k r0PL)$ caused reduced vision in four of the 27 eyes (15%), or 1.9%
W+
tI(JZ of operated eyes. Three of these four eyes had undergone
$dAQ'\f7 intracapsular cataract extraction and the fourth eye had an
o9)pOwk7; opaque posterior capsule. No one had bilateral vision
tETT\y|' impairment as a result of cataract surgery. Surprisingly, no
pK=$)<I"6 particular demographic factors (such as age, gender, rural
wB6ILTu1 residence, occupation, employment status, health insurance
'p=5hsG status, ethnicity) were related to the presence of unoperated
Kq}/`P cataract.
S<"M5e Conclusions: Although the overall prevalence of cataract is
vn"2"hPF| quite high, no particular subgroup is systematically underserviced
csg:#-gE in terms of cataract surgery. Overall, the results of
FLI\SF< cataract surgery are very good, with the majority of eyes
Nx~9U
g achieving driving vision following cataract extraction.
~b+TkPU Key words: cataract extraction, health planning, health
=5NrkCk#V services accessibility, prevalence
aC0[ OmbG INTRODUCTION
fY@Y$S`Fh Cataract is the leading cause of blindness worldwide and, in
1iq,Gd-G. Australia, cataract extractions account for the majority of all
~F8M_ ophthalmic procedures.1 Over the period 1985–94, the rate
:[:5^R of cataract surgery in Australia was twice as high as would be
r
j qX| expected from the growth in the elderly population.1
-
lHSojq~H Although there have been a number of studies reporting
0z)
8i P the prevalence of cataract in various populations,2–6 there is
'< ]:su+ little information about determinants of cataract surgery in
WPVur{?< the population. A previous survey of Australian ophthalmologists
}} cz95 showed that patient concern and lifestyle, rather
Bw-<xwD than visual acuity itself, are the primary factors for referral
yX%T-/XJ for cataract surgery.7 This supports prior research which has
12 HBq8o shown that visual acuity is not a strong predictor of need for
OjxaA[$ cataract surgery.8,9 Elsewhere, socioeconomic status has
yidUtSv=, been shown to be related to cataract surgery rates.10
E"!I[ To appropriately plan health care services, information is
2N_8ahc needed about the prevalence of age-related cataract in the
;xFx%^M}br community as well as the factors associated with cataract
dz
fR ^Gv surgery. The purpose of this study is to quantify the prevalence
,at"Q$)T of any cataract in Australia, to describe the factors
[.\uHt related to unoperated cataract in the community and to
H..g2;
D describe the visual outcomes of cataract surgery.
n1OxT"tD METHODS
@UCI^a~w Study population
n_;qB7,, Details about the study methodology for the Visual
E$5)]<p! < Impairment Project have been published previously.11
[{.e1s<EK Briefly, cluster sampling within three strata was employed to
gL%%2 }$ recruit subjects aged 40 years and over to participate.
*0>![v Within the Melbourne Statistical Division, nine pairs of
KL:x!GsV5e census collector districts were randomly selected. Fourteen
%:I\M)t}k nursing homes within a 5 km radius of these nine test sites
_'9("m V were randomly chosen to recruit nursing home residents.
$hexJzX Clinical and Experimental Ophthalmology (2000) 28, 77–82
; MU8@?yN Original Article
, 'WhF- Operated and unoperated cataract in Australia
-2NXQ+m ; Catherine A McCarty PhD, MPH, Mukesh B Nanjan PhD, Hugh R Taylor MD
R `}C/'Ty Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
>TSPEvWc n Correspondence: Dr Cathy McCarty MPH, Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, 32 Gisborne Street, East Melbourne,
yWI30hW Victoria 3002, Australia. Email:
cathy@cera.unimelb.edu.au 3IXai)6U 78 McCarty et al.
s Xyc _3N Finally, four pairs of census collector districts in four rural
E(J@A'cX Victorian communities were randomly selected to recruit rural
cM&5SyxiuE residents. A household census was conducted to identify
YyOPgF] M eligible residents aged 40 years and over who had been a
Ore>j+ resident at that address for at least 6 months. At the time of
VyQ@. Lm the household census, basic information about age, sex,
12
y=Eh country of birth, language spoken at home, education, use of
}DH3_M!
corrective spectacles and use of eye care services was collected.
0=N,y Eligible residents were then invited to attend a local
GM&< ?K1 examination site for a more detailed interview and examination.
}xZR`xP( The study protocol was approved by the Royal Victorian
cd_\?7 Eye and Ear Hospital Human Research Ethics Committee.
q-7C7q Assessment of cataract
5u/d r9n A standardized ophthalmic examination was performed after
<2b&AF{En pupil dilatation with one drop of 10% phenylephrine
)`,||sQ hydrochloride. Lens opacities were graded clinically at the
MA}~bfB time of the examination and subsequently from photos using
_ ~q!<-Z the Wilmer cataract photo-grading system.12 Cortical and
x`7Ch3`4} posterior subcapsular (PSC) opacities were assessed on
9f UD68Nob retroillumination and measured as the proportion (in 1/16)
rGa@!^hk of pupil circumference occupied by opacity. For this analysis,
'gBns cortical cataract was defined as 4/16 or greater opacity,
isU7nlc! PSC cataract was defined as opacity equal to or greater than
b2L9%8h 1 mm2 and nuclear cataract was defined as opacity equal to
Uc>kiWW or greater than Wilmer standard 2,12 independent of visual
TA2HAMx) acuity. Examples of the minimum opacities defined as cortical,
U}#3LFr.? nuclear and PSC cataract are presented in Figure 1.
o%EzK;Df Bilateral congenital cataracts or cataracts secondary to
.AB n$ml] intraocular inflammation or trauma were excluded from the
TJYup%q analysis. Two cases of bilateral secondary cataract and eight
E[$"~|7|$ cases of bilateral congenital cataract were excluded from the
[z:.52@! analyses.
VtP^fM^{ A Topcon® SL5 photo slit-lamp (Topcon America Corp.,
"0*yD[2 Paramus, NJ, USA) with a 0.1 mm slit beam of 9.0 mm in
3(2WO^zX { height set to an incident angle of 30° was used for examinations.
vR"?XqgZ Ektachrome® 200 ASA colour slide film (Eastman
RB\
Hl Kodak Company, Rochester, NY, USA) was used to photograph
bEQy5AX the nuclear opacities. The cortical opacities were
x3>ZO.Q photographed with an Oxford® retroillumination camera
D_SXxP[! g (Marcher Enterprises Ltd, Hereford, UK) and T-MAX® 400
8k( zU>^ film (Eastman Kodak). Photographs were graded separately
$&25hvK, by two research assistants and discrepancies were adjudicated
uOQ!av2"Rf by an independent reviewer. Any discrepancies
f-.dL between the clinical grades and the photograph grades were
&9+]{jXF resolved. Except in cases where photographs were missing,
"U"phLX the photograph grades were used in the analyses. Photograph
gg0rkg
grades were available for 4301 (84%) for cortical
N!PPL"5z
cataract, 4147 (81%) for nuclear cataract and 4303 (84%)
6N49q-.Lg for PSC cataract. Cataract status was classified according to
SD/=e3 the severity of the opacity in the worse eye.
lGlh/B% Assessment of risk factors
zAW+!C
. A standardized questionnaire was used to obtain information
elqm/u about education, employment and ethnic background.11
zb]e{$q2C Specific information was elicited on the occurrence, duration
aZ,j1j0p and treatment of a number of medical conditions,
exZgk2[0 including ocular trauma, arthritis, diabetes, gout, hypertension
`<3%`4z/ and mental illness. Information about the use, dose and
sck.2-f" duration of tobacco, alcohol, analgesics and steriods were
K/YXLR + collected, and a food frequency questionnaire was used to
rNK<p3=7) determine current consumption of dietary sources of antioxidants
:hBLi99
o and use of vitamin supplements.
1gA^Qv~? Data management and statistical analysis
zv-9z Data were collected either by direct computer entry with a
'uW&ADp questionnaire programmed in Paradox© (Carel Corporation,
MpVZ
L29) Ottawa, Canada) with internal consistency checks, or
43}uW,P on self-coding forms. Open-ended responses were coded at
Al3*? H& a later time. Data that were entered on the self-coded forms
{/|tVc63 were entered into a computer with double data entry and
z',f'3+ reconciliation of any inconsistencies. Data range and consistency
R0#'t+7^ checks were performed on the entire data set.
Pil_zQ4 SAS© version 6.1 (SAS Institute, Cary, North Carolina) was
[ KDNKK employed for statistical analyses.
KY%LqcC Ninety-five per cent confidence limits around the agespecific
NY
GWA4L rates were calculated according to Cochran13 to
X%98k'h.y account for the effect of the cluster sampling. Ninety-five
OJ1MV 7& per cent confidence limits around age-standardized rates
5^97#;Q;J" were calculated according to Breslow and Day.14 The strataspecific
uC! dy data were weighted according to the 1996
_]zH4o<p Australian Bureau of Statistics census data15 to reflect the
Gn %"
B6 cataract prevalence in the entire Victorian population.
H
va/C{Y Univariate analyses with Student’s t-tests and chi-squared
".{'h tests were first employed to evaluate risk factors for unoperated
^&lkh@Y1q cataract. Any factors with P < 0.10 were then fitted
3>6rO4, into a backwards stepwise logistic regression model. For the
k#n%at.g Figure 1. Minimum levels of cortical (a), nuclear (b), and posterior subcapsular (c) cataract.
9DmFa5E final multivariate models, P < 0.05 was considered statistically
P&h]uNu significant. Design effect was assessed through the use
,FwJ0V of cluster-specific models and multivariate models. The
z~th{4#E; design effect was assumed to be additive and an adjustment
)~CNh5z6Y made in the variance by adding the variance associated with
2Z-QVwa*U
the design effect prior to constructing the 95% confidence
&W}6Xg( limits.
)S`=y-L$ RESULTS
A`* l+M^z Study population
T0@$6&b%\z A total of 3271 (83%) of the Melbourne residents, 403
h!7Lvh`o (90%) Melbourne nursing home residents, and 1473 (92%)
92ngSaNC rural residents participated. In general, non-participants did
*#1J not differ from participants.16 The study population was
{(l,Uhxl"" representative of the Victorian population and Australia as
Mzw:c# a whole.
m:c0S8#: The Melbourne residents ranged in age from 40 to
vwzElZ{C:v 98 years (mean = 59) and 1511 (46%) were male. The
&YBZuq2? Melbourne nursing home residents ranged in age from 46 to
t)mc~M9w 101 years (mean = 82) and 85 (21%) were men. The rural
Q)=2%X residents ranged in age from 40 to 103 years (mean = 60)
\z
eu vD and 701 (47.5%) were men.
iqFC~].) Prevalence of cataract and prior cataract surgery
rN,T}M=2 As would be expected, the rate of any cataract increases
<`u_O!h dramatically with age (Table 1). The weighted rate of any
nG-DtG^z cataract in Victoria was 21.5% (95% CL 18.1, 24.9).
6),!sO?
Although the rates varied somewhat between the three
B}J0d strata, they were not significantly different as the 95% confidence
/iL*) limits overlapped. The per cent of cataractous eyes
hrGX65> with best-corrected visual acuity of less than 6/12 was 12.5%
!;K zR& (65/520) for cortical cataract, 18% for nuclear cataract
i.^:xZ (97/534) and 14.4% (27/187) for PSC cataract. Cataract
Tv9\`F[ surgery also rose dramatically with age. The overall
}D-jTZlC weighted rate of prior cataract surgery in Victoria was
D^}2ilk! 3.79% (95% CL 2.97, 4.60) (Table 2).
Z@bSkO<Y Risk factors for unoperated cataract
ght3# Cases of cataract that had not been removed were classified
HBZ6 Pj as unoperated cataract. Risk factor analyses for unoperated
,N
nh$F cataract were not performed with the nursing home residents
%j2$ ezud as information about risk factor exposure was not
YABi`;R]' available for this cohort. The following factors were assessed
D/=
k9[b! in relation to unoperated cataract: age, sex, residence
li{!Jp5]1b (urban/rural), language spoken at home (a measure of ethnic
TM|PwY integration), country of birth, parents’ country of birth (a
[Zzztn+ measure of ethnicity), years since migration, education, use
qlnA7cK! of ophthalmic services, use of optometric services, private
o' v!83$L health insurance status, duration of distance glasses use,
~=I:go glaucoma, age-related maculopathy and employment status.
nPDoK!r' In this cross sectional study it was not possible to assess the
`Y^l.%AZZ level of visual acuity that would predict a patient’s having
Xoha.6$l5 cataract surgery, as visual acuity data prior to cataract
rHuzGSX54 surgery were not available.
qe22 kE# The significant risk factors for unoperated cataract in univariate
3w"_Onwk analyses were related to: whether a participant had
NNwGRoDco ever seen an optometrist, seen an ophthalmologist or been
Az-!X!O*f diagnosed with glaucoma; and participants’ employment
"d/uyS$6 status (currently employed) and age. These significant
uvw1 _j? factors were placed in a backwards stepwise logistic regression
nyxoa/ model. The factors that remained significantly related
>&k`NXS|V to unoperated cataract were whether participants had ever
Z~}9^ (qc seen an ophthalmologist, seen an optometrist and been
6{0MprY diagnosed with glaucoma. None of the demographic factors
sZ7~AJ were associated with unoperated cataract in the multivariate
|68u4z K model.
hm
k ~ The per cent of participants with unoperated cataract
'Sesh'2
/ who said that they were dissatisfied or very dissatisfied with
1=C<aRZ b^ Operated and unoperated cataract in Australia 79
JT~Dr KI_ Table 1. Prevalence of any cataracta (excluding previous cataract surgery) by age, gender and cohort
Mz+vT0 Age group Sex Urban Rural Nursing home Weighted total
>>"@0tO (years) (%) (%) (%)
>3~)2)Q 40–49 Male 2.56 4.04 0.00 3.00 (1.91, 4.08)
2\1bQq\ Female 2.61 1.70 0.00 2.36 (1.61, 3.10)
!w@i,zqu 50–59 Male 7.69 6.94 0.00 7.47 (5.80, 9.15)
jw
5 U-zi
Female 6.67 7.56 0.00 6.92 (5.60, 8.24)
q~Al[`K 60–69 Male 20.7 25.0 10.0 22.0 (18.1, 26.0)
=+I-9= Female 27.9 35.7 37.5 30.3 (26.0, 34.7)
#{^qBP[ 70–79 Male 43.1 58.7 39.1 48.1 (41.2, 55.1)
yy[ Y= Female 58.6 66.2 55.6 61.0 (56.0, 65.9)
-yTIv*y 80–89 Male 74.0 89.3 92.0 79.3 (72.3, 86.3)
nR w f;K Female 91.9 97.0 80.2 92.6 (86.4, 98.8)
-M_>]ubG 90 + Male 100.0 100.0 75.0 98.8 (96.2, 100.0)
z.?slYe[ Female 100.0 100.0 93.8 98.6 (97.0, 100.0)
"Nz@jv? Age-standardized
^HtB!Xc
(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)
"WO0rh` aCortical > 4/16, nuclear > standard 2, posterior subcapsular > 1 mm2
pU[yr'D.r their current vision was 30% (290/683), compared with 27%
4S[)5su (26/95) of participants with prior cataract surgery (chisquared,
B#35)QI 1 d.f. = 0.25, P = 0.62).
3-)}.8F Outcomes of cataract surgery
U0srwt97S Two hundred and forty-nine eyes had undergone prior
O6ugN-d> cataract surgery. Of these 249 operated eyes, 49 (20%) were
<P6d
-+ left aphakic, 6 (2.4%) had anterior chamber intraocular
VZ y$0* lenses and 194 (78%) had posterior chamber intraocular
K{V
.N<