ABSTRACT
G
j1_!.T Purpose: To quantify the prevalence of cataract, the outcomes
FqifriLN of cataract surgery and the factors related to
@KA4N` unoperated cataract in Australia.
S$k&vc(0 Methods: Participants were recruited from the Visual
b2]Kx&! Impairment Project: a cluster, stratified sample of more than
`kr?j:g 5000 Victorians aged 40 years and over. At examination
HqTjl4ai sites interviews, clinical examinations and lens photography
W l16`9 were performed. Cataract was defined in participants who
yBRC*0+Vy had: had previous cataract surgery, cortical cataract greater
4sM.C9W than 4/16, nuclear greater than Wilmer standard 2, or
~v83pu1!2s posterior subcapsular greater than 1 mm2.
KU;9}!# Results: The participant group comprised 3271 Melbourne
iCyfOh residents, 403 Melbourne nursing home residents and 1473
2[CdZ(k]5 rural residents.The weighted rate of any cataract in Victoria
I l.K"ll was 21.5%. The overall weighted rate of prior cataract
tu?MY p; surgery was 3.79%. Two hundred and forty-nine eyes had
"mNq&$ had prior cataract surgery. Of these 249 procedures, 49
FN;^"H (20%) were aphakic, 6 (2.4%) had anterior chamber
o14cwb intraocular lenses and 194 (78%) had posterior chamber
c"Sq~X intraocular lenses.Two hundred and eleven of these operated
.~}1+\~5 eyes (85%) had best-corrected visual acuity of 6/12 or
d7i]FV better, the legal requirement for a driver’s license.Twentyseven
0;ji65 (11%) had visual acuity of less than 6/18 (moderate
cAc@n6[`3 vision impairment). Complications of cataract surgery
?s _5&j7 caused reduced vision in four of the 27 eyes (15%), or 1.9%
6&-(&(
_ of operated eyes. Three of these four eyes had undergone
D0q":WvE intracapsular cataract extraction and the fourth eye had an
yZ`wfj$Jj opaque posterior capsule. No one had bilateral vision
Uwi7) impairment as a result of cataract surgery. Surprisingly, no
N?>vd* particular demographic factors (such as age, gender, rural
jSA jcLR residence, occupation, employment status, health insurance
7
yba04D) status, ethnicity) were related to the presence of unoperated
o lxByzTh> cataract.
j)GtEP<n# Conclusions: Although the overall prevalence of cataract is
W];dD$Oqg quite high, no particular subgroup is systematically underserviced
^VACf|0 in terms of cataract surgery. Overall, the results of
u4_9)P`]0 cataract surgery are very good, with the majority of eyes
F\KUZ[% achieving driving vision following cataract extraction.
/SrAW`;" Key words: cataract extraction, health planning, health
l \?c}7k services accessibility, prevalence
hG:|9Sol, INTRODUCTION
\j)E5b+ Cataract is the leading cause of blindness worldwide and, in
AFfAtu Australia, cataract extractions account for the majority of all
\_U$"/$4VH ophthalmic procedures.1 Over the period 1985–94, the rate
TuYCR>P[ of cataract surgery in Australia was twice as high as would be
sse.*75U expected from the growth in the elderly population.1
M|[o aanY' Although there have been a number of studies reporting
))i }7chc the prevalence of cataract in various populations,2–6 there is
kM@zyDn, little information about determinants of cataract surgery in
i2^>vYCsl the population. A previous survey of Australian ophthalmologists
kE(mVyLQ showed that patient concern and lifestyle, rather
tdaL/rRe than visual acuity itself, are the primary factors for referral
F*K_+
?m for cataract surgery.7 This supports prior research which has
'XBFv9& shown that visual acuity is not a strong predictor of need for
?KI,cl cataract surgery.8,9 Elsewhere, socioeconomic status has
d5z`B H. been shown to be related to cataract surgery rates.10
~F?u)~QZ# To appropriately plan health care services, information is
V,?yPi$#E needed about the prevalence of age-related cataract in the
"2T#M
O/ community as well as the factors associated with cataract
O5t[ surgery. The purpose of this study is to quantify the prevalence
4I?^ t" of any cataract in Australia, to describe the factors
qWKAM@ related to unoperated cataract in the community and to
$"&{aa
describe the visual outcomes of cataract surgery.
% -e 82J1 METHODS
AjgF6[B Study population
Gm.]sE?. Details about the study methodology for the Visual
9,'ncw$/C Impairment Project have been published previously.11
yqiq,=OvP Briefly, cluster sampling within three strata was employed to
U2~kJ
recruit subjects aged 40 years and over to participate.
Q( {
r@*g Within the Melbourne Statistical Division, nine pairs of
=k:,qft2 census collector districts were randomly selected. Fourteen
h.s+)
fl\ nursing homes within a 5 km radius of these nine test sites
(4
1|'eB\\ were randomly chosen to recruit nursing home residents.
B i<Q=x'Z; Clinical and Experimental Ophthalmology (2000) 28, 77–82
_1L![-ac Original Article
x*&|0n.D Operated and unoperated cataract in Australia
nSAdCJ;4 Catherine A McCarty PhD, MPH, Mukesh B Nanjan PhD, Hugh R Taylor MD
[o5Hl^ Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
m&?r%x n Correspondence: Dr Cathy McCarty MPH, Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, 32 Gisborne Street, East Melbourne,
>q1L2',pK Victoria 3002, Australia. Email:
cathy@cera.unimelb.edu.au ;Nj7qt 78 McCarty et al.
"E?2xf|. Finally, four pairs of census collector districts in four rural
@)&=% Victorian communities were randomly selected to recruit rural
T+k{W6 residents. A household census was conducted to identify
dIBE!4 V[ eligible residents aged 40 years and over who had been a
N;j)k; resident at that address for at least 6 months. At the time of
&<U0ZvrsH the household census, basic information about age, sex,
W+X6@/BO country of birth, language spoken at home, education, use of
.oUTqki corrective spectacles and use of eye care services was collected.
<r`2)[7N Eligible residents were then invited to attend a local
7 uKY24 examination site for a more detailed interview and examination.
'>ssqBnI The study protocol was approved by the Royal Victorian
[ )dXI IM Eye and Ear Hospital Human Research Ethics Committee.
b4ONh% Assessment of cataract
6@0OQb A standardized ophthalmic examination was performed after
.KUv(- pupil dilatation with one drop of 10% phenylephrine
:'l^kSP_*C hydrochloride. Lens opacities were graded clinically at the
D"?fn<2 time of the examination and subsequently from photos using
$ ,}E the Wilmer cataract photo-grading system.12 Cortical and
CZI6 6pDy posterior subcapsular (PSC) opacities were assessed on
:G2k5xD/E retroillumination and measured as the proportion (in 1/16)
Rt!FPoN,y of pupil circumference occupied by opacity. For this analysis,
@A89eZbW cortical cataract was defined as 4/16 or greater opacity,
j; y#[| PSC cataract was defined as opacity equal to or greater than
L(-b@Joh 1 mm2 and nuclear cataract was defined as opacity equal to
b@f$nS
B or greater than Wilmer standard 2,12 independent of visual
&Ao+X=qw acuity. Examples of the minimum opacities defined as cortical,
dCk3;XU nuclear and PSC cataract are presented in Figure 1.
&NoS=(s, Bilateral congenital cataracts or cataracts secondary to
(ECnMti
+ intraocular inflammation or trauma were excluded from the
k!HK 97qA analysis. Two cases of bilateral secondary cataract and eight
$5<#n@
cases of bilateral congenital cataract were excluded from the
-w_QJ_z_ analyses.
_p&]|~a A Topcon® SL5 photo slit-lamp (Topcon America Corp.,
~r`9+b[9{ Paramus, NJ, USA) with a 0.1 mm slit beam of 9.0 mm in
SB
|Qa}62 height set to an incident angle of 30° was used for examinations.
NzSoqh{R Ektachrome® 200 ASA colour slide film (Eastman
lWc:$qnR-K Kodak Company, Rochester, NY, USA) was used to photograph
L3 --r the nuclear opacities. The cortical opacities were
aV?@s4 photographed with an Oxford® retroillumination camera
()+<)hg}2 (Marcher Enterprises Ltd, Hereford, UK) and T-MAX® 400
`~Zs0 film (Eastman Kodak). Photographs were graded separately
@&:ar by two research assistants and discrepancies were adjudicated
PCM-i{6/ by an independent reviewer. Any discrepancies
(>GK\=:< between the clinical grades and the photograph grades were
7Kal"Ew resolved. Except in cases where photographs were missing,
!~&R"2/ the photograph grades were used in the analyses. Photograph
5>j)kx=J9 grades were available for 4301 (84%) for cortical
[[Fx[ cataract, 4147 (81%) for nuclear cataract and 4303 (84%)
tj4VWJK for PSC cataract. Cataract status was classified according to
CS-uNG6 the severity of the opacity in the worse eye.
;YX4:OBqr Assessment of risk factors
I'iGt~4$ A standardized questionnaire was used to obtain information
;z:UN} about education, employment and ethnic background.11
&8_gRP Specific information was elicited on the occurrence, duration
b7tOo7a H) and treatment of a number of medical conditions,
5HO9+i including ocular trauma, arthritis, diabetes, gout, hypertension
>W`4aA and mental illness. Information about the use, dose and
`~;rblo; duration of tobacco, alcohol, analgesics and steriods were
C@W"yYt collected, and a food frequency questionnaire was used to
&2zq%((r determine current consumption of dietary sources of antioxidants
e\JojaV and use of vitamin supplements.
}S$@ Ez6 Data management and statistical analysis
x{c/$+Z[ Data were collected either by direct computer entry with a
Z%Zd2
v questionnaire programmed in Paradox© (Carel Corporation,
),!;| bh Ottawa, Canada) with internal consistency checks, or
5~WGZc on self-coding forms. Open-ended responses were coded at
WT`4s a later time. Data that were entered on the self-coded forms
XWs"jt were entered into a computer with double data entry and
R&';Oro reconciliation of any inconsistencies. Data range and consistency
ez!C? checks were performed on the entire data set.
09kt[
SAS© version 6.1 (SAS Institute, Cary, North Carolina) was
s nnbb0J employed for statistical analyses.
'@CR\5 @ Ninety-five per cent confidence limits around the agespecific
e-*.Ca rates were calculated according to Cochran13 to
3UQ;X**F account for the effect of the cluster sampling. Ninety-five
1,~SS per cent confidence limits around age-standardized rates
0,rTdjH7
were calculated according to Breslow and Day.14 The strataspecific
O
Wj@<N data were weighted according to the 1996
(%o2jroQ# Australian Bureau of Statistics census data15 to reflect the
X2i}vjkY cataract prevalence in the entire Victorian population.
9Q-*@6G Univariate analyses with Student’s t-tests and chi-squared
{ e5/+W tests were first employed to evaluate risk factors for unoperated
JA_BKA cataract. Any factors with P < 0.10 were then fitted
3^~KB'RZ into a backwards stepwise logistic regression model. For the
`TPOCxM Mo Figure 1. Minimum levels of cortical (a), nuclear (b), and posterior subcapsular (c) cataract.
t2iv(swTe final multivariate models, P < 0.05 was considered statistically
R$Tp8G>j significant. Design effect was assessed through the use
(q7
Ry4- of cluster-specific models and multivariate models. The
P7f,OY<@%o design effect was assumed to be additive and an adjustment
(%:>T
Q( made in the variance by adding the variance associated with
t/PlcV_M" the design effect prior to constructing the 95% confidence
d/e|'MPX limits.
d{de6 ` RESULTS
TSsKfexQ Study population
.pvV1JA' A total of 3271 (83%) of the Melbourne residents, 403
5rV(( (90%) Melbourne nursing home residents, and 1473 (92%)
H7kPM[ rural residents participated. In general, non-participants did
cFF*Z=L_ not differ from participants.16 The study population was
5+jf/}tA representative of the Victorian population and Australia as
zn@N'R/ a whole.
tDCw- The Melbourne residents ranged in age from 40 to
M}wXJ8aF? 98 years (mean = 59) and 1511 (46%) were male. The
q0bHB_|wL Melbourne nursing home residents ranged in age from 46 to
%D`,k*X 101 years (mean = 82) and 85 (21%) were men. The rural
D*Q.G8( residents ranged in age from 40 to 103 years (mean = 60)
Q!FLR>8 and 701 (47.5%) were men.
?<yM7O,4 Prevalence of cataract and prior cataract surgery
;|cTHGxbE As would be expected, the rate of any cataract increases
Wi}FY }f dramatically with age (Table 1). The weighted rate of any
TV}}dw cataract in Victoria was 21.5% (95% CL 18.1, 24.9).
m%8qZzqk Although the rates varied somewhat between the three
1]T`n /d V strata, they were not significantly different as the 95% confidence
S-nlr@w8 limits overlapped. The per cent of cataractous eyes
9=/N|m8. with best-corrected visual acuity of less than 6/12 was 12.5%
)P>u9=?,=E (65/520) for cortical cataract, 18% for nuclear cataract
OW(&s,|6x (97/534) and 14.4% (27/187) for PSC cataract. Cataract
6dEyv99 surgery also rose dramatically with age. The overall
rB%$;<`/ weighted rate of prior cataract surgery in Victoria was
8
%~t 3.79% (95% CL 2.97, 4.60) (Table 2).
5ZAb]F90 Risk factors for unoperated cataract
2n`Lg4=
Cases of cataract that had not been removed were classified
m!OMrZ%)} as unoperated cataract. Risk factor analyses for unoperated
@)8]e
S7 cataract were not performed with the nursing home residents
u.|~$yP.! as information about risk factor exposure was not
5H:@8,B available for this cohort. The following factors were assessed
C+MSVc in relation to unoperated cataract: age, sex, residence
wp.TfKxw (urban/rural), language spoken at home (a measure of ethnic
".~{:= integration), country of birth, parents’ country of birth (a
7=*VpX1 measure of ethnicity), years since migration, education, use
WIh@y2&R of ophthalmic services, use of optometric services, private
i3
)xX@3 health insurance status, duration of distance glasses use,
[ev-^[ glaucoma, age-related maculopathy and employment status.
'?Iif#Z1 In this cross sectional study it was not possible to assess the
>AI<60/< level of visual acuity that would predict a patient’s having
,dd WBwMK cataract surgery, as visual acuity data prior to cataract
J%dJw} surgery were not available.
twk&-:' The significant risk factors for unoperated cataract in univariate
%>XN%t'6aT analyses were related to: whether a participant had
s!6=|SS7 ever seen an optometrist, seen an ophthalmologist or been
`!w^0kZ diagnosed with glaucoma; and participants’ employment
8HoP(+? status (currently employed) and age. These significant
C 7nKk/r factors were placed in a backwards stepwise logistic regression
\-.
Tg!Q6 model. The factors that remained significantly related
iG[?
]] to unoperated cataract were whether participants had ever
^@}#me@ seen an ophthalmologist, seen an optometrist and been
N5q725zJ diagnosed with glaucoma. None of the demographic factors
j.QHkI1. were associated with unoperated cataract in the multivariate
BQjam+u6 model.
Z|`fHO3j The per cent of participants with unoperated cataract
A'"-m)1P who said that they were dissatisfied or very dissatisfied with
9)yG.9d1 Operated and unoperated cataract in Australia 79
Y5jYmP< Table 1. Prevalence of any cataracta (excluding previous cataract surgery) by age, gender and cohort
;1LG&h,K Age group Sex Urban Rural Nursing home Weighted total
U4_"aT>My (years) (%) (%) (%)
: z~!p~ 40–49 Male 2.56 4.04 0.00 3.00 (1.91, 4.08)
@
u1Q-: Female 2.61 1.70 0.00 2.36 (1.61, 3.10)
kQ }s/* 50–59 Male 7.69 6.94 0.00 7.47 (5.80, 9.15)
&LU'.jY Female 6.67 7.56 0.00 6.92 (5.60, 8.24)
r69WD
. 60–69 Male 20.7 25.0 10.0 22.0 (18.1, 26.0)
BQ#jwu0e Female 27.9 35.7 37.5 30.3 (26.0, 34.7)
VC=6uB 70–79 Male 43.1 58.7 39.1 48.1 (41.2, 55.1)
yH(V&T