ABSTRACT
XQ1]F{?/
H Purpose: To quantify the prevalence of cataract, the outcomes
NKY|Z\ of cataract surgery and the factors related to
O:BdZ5
b unoperated cataract in Australia.
=By@%ioIGG Methods: Participants were recruited from the Visual
txEN7! Impairment Project: a cluster, stratified sample of more than
Y e0,0Fpw 5000 Victorians aged 40 years and over. At examination
9qX$ sites interviews, clinical examinations and lens photography
'}agi.z were performed. Cataract was defined in participants who
?K$&|w%{3 had: had previous cataract surgery, cortical cataract greater
@$slGY than 4/16, nuclear greater than Wilmer standard 2, or
TX)W.2u= posterior subcapsular greater than 1 mm2.
Q#MB=:0{ Results: The participant group comprised 3271 Melbourne
(KI9j7 residents, 403 Melbourne nursing home residents and 1473
`2>p#` rural residents.The weighted rate of any cataract in Victoria
o
Mz{j: was 21.5%. The overall weighted rate of prior cataract
=r]l"T
surgery was 3.79%. Two hundred and forty-nine eyes had
stiF`l had prior cataract surgery. Of these 249 procedures, 49
cb-IRGF (20%) were aphakic, 6 (2.4%) had anterior chamber
%??v?
M* intraocular lenses and 194 (78%) had posterior chamber
&mX_\w/% intraocular lenses.Two hundred and eleven of these operated
Zk`y"[ J eyes (85%) had best-corrected visual acuity of 6/12 or
cGm3LS6]* better, the legal requirement for a driver’s license.Twentyseven
cB&_':F (11%) had visual acuity of less than 6/18 (moderate
=
#-zK:4 vision impairment). Complications of cataract surgery
[IHo
~ caused reduced vision in four of the 27 eyes (15%), or 1.9%
KHx2$*E_ of operated eyes. Three of these four eyes had undergone
E6 oC^,ZRy intracapsular cataract extraction and the fourth eye had an
)>2L(~W opaque posterior capsule. No one had bilateral vision
ILr=<j impairment as a result of cataract surgery. Surprisingly, no
pW+uVv, particular demographic factors (such as age, gender, rural
*I :c@iCNJ residence, occupation, employment status, health insurance
qu^g~"s status, ethnicity) were related to the presence of unoperated
ZtZ3I?%U3 cataract.
OUWK Conclusions: Although the overall prevalence of cataract is
=r+K2]z,L quite high, no particular subgroup is systematically underserviced
N]FRL\K in terms of cataract surgery. Overall, the results of
Uha.8
cataract surgery are very good, with the majority of eyes
8XJi }YPQ achieving driving vision following cataract extraction.
G,>YzjMY` Key words: cataract extraction, health planning, health
uZ8-? services accessibility, prevalence
u7mPp3ZYK INTRODUCTION
nA0%M1a Cataract is the leading cause of blindness worldwide and, in
mrr]{K Australia, cataract extractions account for the majority of all
2d*bF. ophthalmic procedures.1 Over the period 1985–94, the rate
NWh1u` of cataract surgery in Australia was twice as high as would be
M(L6PyEa!Y expected from the growth in the elderly population.1
QM8Ic,QFvo Although there have been a number of studies reporting
,c"J[$i
$ the prevalence of cataract in various populations,2–6 there is
.K84"Gdx little information about determinants of cataract surgery in
^mn!;nu the population. A previous survey of Australian ophthalmologists
;N#}3lpLqg showed that patient concern and lifestyle, rather
^"O>EY': than visual acuity itself, are the primary factors for referral
FzEs1hpl for cataract surgery.7 This supports prior research which has
HnArj_E shown that visual acuity is not a strong predictor of need for
?o[h$7`o6 cataract surgery.8,9 Elsewhere, socioeconomic status has
F%<*a
,m6g been shown to be related to cataract surgery rates.10
ATqblU>D To appropriately plan health care services, information is
@\nQ{\^; needed about the prevalence of age-related cataract in the
A
:ts_* community as well as the factors associated with cataract
,
r*Kxy surgery. The purpose of this study is to quantify the prevalence
k JmwR of any cataract in Australia, to describe the factors
h&K$(}X related to unoperated cataract in the community and to
@Dfg6<0 describe the visual outcomes of cataract surgery.
mDz44XO METHODS
~588M
8~ Study population
}Q4Vy Details about the study methodology for the Visual
x?o#}:S Impairment Project have been published previously.11
Eo2`Vr9g Briefly, cluster sampling within three strata was employed to
j7ZxA* recruit subjects aged 40 years and over to participate.
"
<+~u
z Within the Melbourne Statistical Division, nine pairs of
!O%!A<3 census collector districts were randomly selected. Fourteen
Xg
d-^ nursing homes within a 5 km radius of these nine test sites
VIdKe&, were randomly chosen to recruit nursing home residents.
w\s`8S Clinical and Experimental Ophthalmology (2000) 28, 77–82
0F-{YQr> Original Article
Y >w7%N Operated and unoperated cataract in Australia
f~wON>$K Catherine A McCarty PhD, MPH, Mukesh B Nanjan PhD, Hugh R Taylor MD
LUD. Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
;+XrCy!.)L n Correspondence: Dr Cathy McCarty MPH, Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, 32 Gisborne Street, East Melbourne,
cy.r/Z} Victoria 3002, Australia. Email:
cathy@cera.unimelb.edu.au VA[EY`8 78 McCarty et al.
m|W17LhW{ Finally, four pairs of census collector districts in four rural
,B'=$PO% Victorian communities were randomly selected to recruit rural
BeLD`
4K residents. A household census was conducted to identify
_M/N_Fm eligible residents aged 40 years and over who had been a
z.8 nYL5^} resident at that address for at least 6 months. At the time of
iOg4(SPci the household census, basic information about age, sex,
Zpg;hj5_ country of birth, language spoken at home, education, use of
9{OO'at? corrective spectacles and use of eye care services was collected.
)9"^ D Eligible residents were then invited to attend a local
_l9fNf!@ examination site for a more detailed interview and examination.
,:PMS8pS The study protocol was approved by the Royal Victorian
x 4_MbUe Eye and Ear Hospital Human Research Ethics Committee.
IMwV9rF Assessment of cataract
#4mRMsW5" A standardized ophthalmic examination was performed after
X3G593ts pupil dilatation with one drop of 10% phenylephrine
lo>9 \ Po hydrochloride. Lens opacities were graded clinically at the
:rU.5(, time of the examination and subsequently from photos using
BS fmS(. the Wilmer cataract photo-grading system.12 Cortical and
zA9q`ePS posterior subcapsular (PSC) opacities were assessed on
5zBA ]1PY retroillumination and measured as the proportion (in 1/16)
FDD=I\Ic of pupil circumference occupied by opacity. For this analysis,
Zb=NcEPGy cortical cataract was defined as 4/16 or greater opacity,
k)-+ZmMOh PSC cataract was defined as opacity equal to or greater than
1"Oe*@`pV 1 mm2 and nuclear cataract was defined as opacity equal to
?YR;o4 or greater than Wilmer standard 2,12 independent of visual
76rv$z{g^ acuity. Examples of the minimum opacities defined as cortical,
K +vD&Z^ nuclear and PSC cataract are presented in Figure 1.
HNS^:XR Bilateral congenital cataracts or cataracts secondary to
\)/qCeiZ intraocular inflammation or trauma were excluded from the
6d]4
%Q T analysis. Two cases of bilateral secondary cataract and eight
<@(\z
cases of bilateral congenital cataract were excluded from the
LRHod1}mS analyses.
Eh8GqFEM A Topcon® SL5 photo slit-lamp (Topcon America Corp.,
;GM`=M4 Paramus, NJ, USA) with a 0.1 mm slit beam of 9.0 mm in
E>QS^)ih height set to an incident angle of 30° was used for examinations.
a?+C]u?_D Ektachrome® 200 ASA colour slide film (Eastman
\;Q(o$5< Kodak Company, Rochester, NY, USA) was used to photograph
Pr}
l
y the nuclear opacities. The cortical opacities were
ks.p)F>] photographed with an Oxford® retroillumination camera
:epBd3f (Marcher Enterprises Ltd, Hereford, UK) and T-MAX® 400
NxnRQS film (Eastman Kodak). Photographs were graded separately
L-E &m* %
by two research assistants and discrepancies were adjudicated
&'12,'8 by an independent reviewer. Any discrepancies
VgXT4gO! between the clinical grades and the photograph grades were
Ewz cB\m resolved. Except in cases where photographs were missing,
gH(#<f@ZI the photograph grades were used in the analyses. Photograph
\uHC 9}0
grades were available for 4301 (84%) for cortical
t+A*Ws*o cataract, 4147 (81%) for nuclear cataract and 4303 (84%)
]Y]]X[@ for PSC cataract. Cataract status was classified according to
}R+#>
P the severity of the opacity in the worse eye.
ef*Z;HI0 Assessment of risk factors
;v]C8 }L^ A standardized questionnaire was used to obtain information
mxCneX about education, employment and ethnic background.11
!4cCq_ Specific information was elicited on the occurrence, duration
.^A4w;jPU and treatment of a number of medical conditions,
[gUD + including ocular trauma, arthritis, diabetes, gout, hypertension
uzQj+Po and mental illness. Information about the use, dose and
)kjQ W&)g duration of tobacco, alcohol, analgesics and steriods were
/D9#v1b collected, and a food frequency questionnaire was used to
k+[oYd determine current consumption of dietary sources of antioxidants
<=|^\r
!}& and use of vitamin supplements.
p}==aNZK Data management and statistical analysis
z4D)Xy"/ Data were collected either by direct computer entry with a
ASEKP(]v questionnaire programmed in Paradox© (Carel Corporation,
c[,Rhf Ottawa, Canada) with internal consistency checks, or
zK~_e\m on self-coding forms. Open-ended responses were coded at
MjQ>&fUK a later time. Data that were entered on the self-coded forms
xr.;B`T0\' were entered into a computer with double data entry and
V1Ft3Msq reconciliation of any inconsistencies. Data range and consistency
GBZ u<t/ checks were performed on the entire data set.
'S}3lsIE SAS© version 6.1 (SAS Institute, Cary, North Carolina) was
!_+FuF"@ employed for statistical analyses.
I3.JAoB>!
Ninety-five per cent confidence limits around the agespecific
g3'dkS! rates were calculated according to Cochran13 to
]4c*Nh%
8 account for the effect of the cluster sampling. Ninety-five
A]QGaWK per cent confidence limits around age-standardized rates
;K l'[~z were calculated according to Breslow and Day.14 The strataspecific
6E^m*la% data were weighted according to the 1996
$bpu Australian Bureau of Statistics census data15 to reflect the
.0/"~5 cataract prevalence in the entire Victorian population.
+5O^{Ce6 Univariate analyses with Student’s t-tests and chi-squared
$5ea[nc tests were first employed to evaluate risk factors for unoperated
/!5cf;kl*l cataract. Any factors with P < 0.10 were then fitted
DV?c%z`YO into a backwards stepwise logistic regression model. For the
t#f-3zd9 Figure 1. Minimum levels of cortical (a), nuclear (b), and posterior subcapsular (c) cataract.
p;zT #% final multivariate models, P < 0.05 was considered statistically
ou)0tX3j significant. Design effect was assessed through the use
Iza#v0 of cluster-specific models and multivariate models. The
S_AN.8T design effect was assumed to be additive and an adjustment
l:~ >P[ made in the variance by adding the variance associated with
$WW7, the design effect prior to constructing the 95% confidence
#Wl9[W/4 limits.
y9i+EV RESULTS
c.-dwz Study population
_jCu=l_ A total of 3271 (83%) of the Melbourne residents, 403
|1!OwQax (90%) Melbourne nursing home residents, and 1473 (92%)
W+V &