ABSTRACT
h"f_T
[ Purpose: To quantify the prevalence of cataract, the outcomes
a/[)A _- of cataract surgery and the factors related to
k=O
unoperated cataract in Australia.
}-T,cA_H| Methods: Participants were recruited from the Visual
{/qQ=$t Impairment Project: a cluster, stratified sample of more than
\Qf2:[-V0 5000 Victorians aged 40 years and over. At examination
s?
2ikJq sites interviews, clinical examinations and lens photography
WS%yV|e were performed. Cataract was defined in participants who
WYIv&h<h" had: had previous cataract surgery, cortical cataract greater
B#3Q4c$ than 4/16, nuclear greater than Wilmer standard 2, or
LG??Q+`l posterior subcapsular greater than 1 mm2.
s(r4m/ Results: The participant group comprised 3271 Melbourne
0g#x QzE residents, 403 Melbourne nursing home residents and 1473
Ko|gH]B' rural residents.The weighted rate of any cataract in Victoria
`]a0z|2'! was 21.5%. The overall weighted rate of prior cataract
&q#.
> surgery was 3.79%. Two hundred and forty-nine eyes had
RrdLh z2N had prior cataract surgery. Of these 249 procedures, 49
kM(m$Oo. (20%) were aphakic, 6 (2.4%) had anterior chamber
yR"mRy1 intraocular lenses and 194 (78%) had posterior chamber
[2!C^\t intraocular lenses.Two hundred and eleven of these operated
)"7z'ar
eyes (85%) had best-corrected visual acuity of 6/12 or
l hST%3Ld better, the legal requirement for a driver’s license.Twentyseven
qqys`. (11%) had visual acuity of less than 6/18 (moderate
?#RhHD vision impairment). Complications of cataract surgery
-aV(6i*n caused reduced vision in four of the 27 eyes (15%), or 1.9%
EK&0Cn3z of operated eyes. Three of these four eyes had undergone
"8~PfLJ+ intracapsular cataract extraction and the fourth eye had an
?]o(cz opaque posterior capsule. No one had bilateral vision
hD4>mpk impairment as a result of cataract surgery. Surprisingly, no
}_('3C,Ba particular demographic factors (such as age, gender, rural
'8(Ui
B5d residence, occupation, employment status, health insurance
lQy-&d|=#^ status, ethnicity) were related to the presence of unoperated
:6/$/`I0W cataract.
NK'@.=$ Conclusions: Although the overall prevalence of cataract is
>?6HUUQ quite high, no particular subgroup is systematically underserviced
\xcf<y3_ in terms of cataract surgery. Overall, the results of
B#cN'1c cataract surgery are very good, with the majority of eyes
wvxsn!Ao&= achieving driving vision following cataract extraction.
7p1B"% Key words: cataract extraction, health planning, health
qw>vu7/z services accessibility, prevalence
{s@ 0<! INTRODUCTION
X4
Pm&ol Cataract is the leading cause of blindness worldwide and, in
xLfv:Rp Australia, cataract extractions account for the majority of all
ia3!&rZ ophthalmic procedures.1 Over the period 1985–94, the rate
).A9>^6?{ of cataract surgery in Australia was twice as high as would be
vVrM[0*c expected from the growth in the elderly population.1
B^/k`h6J Although there have been a number of studies reporting
6As%<g= the prevalence of cataract in various populations,2–6 there is
7B\Q5fLQ little information about determinants of cataract surgery in
9X
+dp the population. A previous survey of Australian ophthalmologists
9!kp3x/` showed that patient concern and lifestyle, rather
5&O%0`t than visual acuity itself, are the primary factors for referral
7upWM~H^ for cataract surgery.7 This supports prior research which has
pLys%1hg shown that visual acuity is not a strong predictor of need for
#9F>21UU cataract surgery.8,9 Elsewhere, socioeconomic status has
9NNXj^7 been shown to be related to cataract surgery rates.10
L]u^$=rI To appropriately plan health care services, information is
B2'TRXIm1U needed about the prevalence of age-related cataract in the
|\/\FK]?] community as well as the factors associated with cataract
MvnQUZ surgery. The purpose of this study is to quantify the prevalence
^!0z+M:>^ of any cataract in Australia, to describe the factors
u6Wan*I? related to unoperated cataract in the community and to
hUuKkUR+Ir describe the visual outcomes of cataract surgery.
m7C!
}l]9 METHODS
2eA.04F Study population
x5V))~Ou Details about the study methodology for the Visual
';c 6 Impairment Project have been published previously.11
~P"Agpx3u Briefly, cluster sampling within three strata was employed to
/&_
q"y9 recruit subjects aged 40 years and over to participate.
P=6d<no&< Within the Melbourne Statistical Division, nine pairs of
41s\^'^& census collector districts were randomly selected. Fourteen
:FfEjNil nursing homes within a 5 km radius of these nine test sites
~!Nw]lb! were randomly chosen to recruit nursing home residents.
>cg)NqD Clinical and Experimental Ophthalmology (2000) 28, 77–82
/BD'{tZ]Sl Original Article
DwZRx@ Operated and unoperated cataract in Australia
LME&qKe5 Catherine A McCarty PhD, MPH, Mukesh B Nanjan PhD, Hugh R Taylor MD
`JpFqZ'58 Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
Y_n3O@, n Correspondence: Dr Cathy McCarty MPH, Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, 32 Gisborne Street, East Melbourne,
R!
On Victoria 3002, Australia. Email:
cathy@cera.unimelb.edu.au P:N>#
G~z 78 McCarty et al.
F:q8.^HTJ Finally, four pairs of census collector districts in four rural
H{,1-&>| Victorian communities were randomly selected to recruit rural
QKB+mjMH#x residents. A household census was conducted to identify
N3aqNRwlk eligible residents aged 40 years and over who had been a
m'"H1~BW resident at that address for at least 6 months. At the time of
UZrEFpi the household census, basic information about age, sex,
h6^|f%\w*i country of birth, language spoken at home, education, use of
6)ln,{ corrective spectacles and use of eye care services was collected.
kGo2R]Dd[ Eligible residents were then invited to attend a local
>1;jBx>Qy% examination site for a more detailed interview and examination.
(dD7"zQ The study protocol was approved by the Royal Victorian
bv'>4a Eye and Ear Hospital Human Research Ethics Committee.
z rG Assessment of cataract
9d-'%Q>+ A standardized ophthalmic examination was performed after
strM3j##x pupil dilatation with one drop of 10% phenylephrine
*($,ay$&H hydrochloride. Lens opacities were graded clinically at the
EPH" 5$8 time of the examination and subsequently from photos using
l~f3J$OkJ the Wilmer cataract photo-grading system.12 Cortical and
=E%@8ZbK posterior subcapsular (PSC) opacities were assessed on
0XCAnMVo retroillumination and measured as the proportion (in 1/16)
e98QT9 of pupil circumference occupied by opacity. For this analysis,
D"$Y, d cortical cataract was defined as 4/16 or greater opacity,
@48!e-W PSC cataract was defined as opacity equal to or greater than
uax0%~O
\ 1 mm2 and nuclear cataract was defined as opacity equal to
buN@O7\ or greater than Wilmer standard 2,12 independent of visual
{d;z3AB acuity. Examples of the minimum opacities defined as cortical,
tP*Kt'4W nuclear and PSC cataract are presented in Figure 1.
8a)Brl}u Bilateral congenital cataracts or cataracts secondary to
:i?6#_2IC intraocular inflammation or trauma were excluded from the
5R~M@ analysis. Two cases of bilateral secondary cataract and eight
ksOsJ~3) cases of bilateral congenital cataract were excluded from the
.24z+|j analyses.
FGHCHSqLq A Topcon® SL5 photo slit-lamp (Topcon America Corp.,
f7\X3v2W}3 Paramus, NJ, USA) with a 0.1 mm slit beam of 9.0 mm in
6)*fr'P height set to an incident angle of 30° was used for examinations.
,3T"fT-( Ektachrome® 200 ASA colour slide film (Eastman
.\ fpjQW Kodak Company, Rochester, NY, USA) was used to photograph
03v& k the nuclear opacities. The cortical opacities were
eT3!"+p-F photographed with an Oxford® retroillumination camera
[1kQ-Ko` (Marcher Enterprises Ltd, Hereford, UK) and T-MAX® 400
6Yodx$ film (Eastman Kodak). Photographs were graded separately
r|4D.O] by two research assistants and discrepancies were adjudicated
XF)N_
}X^ by an independent reviewer. Any discrepancies
J QnaXjW2 between the clinical grades and the photograph grades were
Sv /P:r
_ resolved. Except in cases where photographs were missing,
~nmFZ]y the photograph grades were used in the analyses. Photograph
6[ 3 K@ grades were available for 4301 (84%) for cortical
}aE' cataract, 4147 (81%) for nuclear cataract and 4303 (84%)
Y`]P&y for PSC cataract. Cataract status was classified according to
/tj]^QspS the severity of the opacity in the worse eye.
8}:$=n4& Assessment of risk factors
aH uMm& A standardized questionnaire was used to obtain information
*`u|1}h| about education, employment and ethnic background.11
2hF^U+I} Specific information was elicited on the occurrence, duration
"J+L]IC?AD and treatment of a number of medical conditions,
^`id/ including ocular trauma, arthritis, diabetes, gout, hypertension
r1-MO`6 and mental illness. Information about the use, dose and
/fb}]e]N duration of tobacco, alcohol, analgesics and steriods were
f<