ABSTRACT
6>uQt:e Purpose: To quantify the prevalence of cataract, the outcomes
#G~wE*VR$ of cataract surgery and the factors related to
-R8/`M8GbD unoperated cataract in Australia.
4+I 3+a" Methods: Participants were recruited from the Visual
|?yE^$a Impairment Project: a cluster, stratified sample of more than
pU@YiwP"]x 5000 Victorians aged 40 years and over. At examination
`GS cRhbh sites interviews, clinical examinations and lens photography
B'#4;R!8P= were performed. Cataract was defined in participants who
xyvND had: had previous cataract surgery, cortical cataract greater
,z oB0([ than 4/16, nuclear greater than Wilmer standard 2, or
=-m(\} posterior subcapsular greater than 1 mm2.
HoL~j( { Results: The participant group comprised 3271 Melbourne
>~^`5a`$uI residents, 403 Melbourne nursing home residents and 1473
6N?#b66 rural residents.The weighted rate of any cataract in Victoria
%rw}u"3T was 21.5%. The overall weighted rate of prior cataract
d~sJ=) surgery was 3.79%. Two hundred and forty-nine eyes had
wePI*."] had prior cataract surgery. Of these 249 procedures, 49
@Jm.HST#S8 (20%) were aphakic, 6 (2.4%) had anterior chamber
G"{4'LlA intraocular lenses and 194 (78%) had posterior chamber
%6N)G!P intraocular lenses.Two hundred and eleven of these operated
dDo6fP2 eyes (85%) had best-corrected visual acuity of 6/12 or
*|^,DGfQ6 better, the legal requirement for a driver’s license.Twentyseven
. Jptj (11%) had visual acuity of less than 6/18 (moderate
X8i[fk1.R vision impairment). Complications of cataract surgery
1y 1_6TZ+ caused reduced vision in four of the 27 eyes (15%), or 1.9%
k~{Fnkt of operated eyes. Three of these four eyes had undergone
VZHr-z$6n intracapsular cataract extraction and the fourth eye had an
Bj; [ opaque posterior capsule. No one had bilateral vision
>B`Cch/'U impairment as a result of cataract surgery. Surprisingly, no
) sRN!~ particular demographic factors (such as age, gender, rural
U&`6&$] residence, occupation, employment status, health insurance
CcBQo8!G status, ethnicity) were related to the presence of unoperated
W8< @sq~I cataract.
w<Zdq}{jO Conclusions: Although the overall prevalence of cataract is
0h^uOA; c quite high, no particular subgroup is systematically underserviced
bAN 10U in terms of cataract surgery. Overall, the results of
h>~jQ&\M cataract surgery are very good, with the majority of eyes
K*TnUQ achieving driving vision following cataract extraction.
1X[73 Key words: cataract extraction, health planning, health
m\_+)eI| services accessibility, prevalence
0K&_D) INTRODUCTION
j[_t6Z Cataract is the leading cause of blindness worldwide and, in
3(aRs?/O Australia, cataract extractions account for the majority of all
]U_5\$ ophthalmic procedures.1 Over the period 1985–94, the rate
f+{c1fb>s of cataract surgery in Australia was twice as high as would be
GVeL~Q expected from the growth in the elderly population.1
sq6>DuBZz Although there have been a number of studies reporting
EV:_Kx8f P the prevalence of cataract in various populations,2–6 there is
Y,3z-Pa=@ little information about determinants of cataract surgery in
`Q:de~+AM{ the population. A previous survey of Australian ophthalmologists
bjuYA/w< showed that patient concern and lifestyle, rather
NKRaQr than visual acuity itself, are the primary factors for referral
,jAx%]@,I for cataract surgery.7 This supports prior research which has
2O?Vr"
A shown that visual acuity is not a strong predictor of need for
=n> iQS cataract surgery.8,9 Elsewhere, socioeconomic status has
&B?@@6 been shown to be related to cataract surgery rates.10
rd XCWK$E To appropriately plan health care services, information is
`)0Rv|? needed about the prevalence of age-related cataract in the
t8L<x community as well as the factors associated with cataract
x eJ9H~^ surgery. The purpose of this study is to quantify the prevalence
^RY n8I of any cataract in Australia, to describe the factors
/p[|DJoM related to unoperated cataract in the community and to
AQE
eIFH describe the visual outcomes of cataract surgery.
s@[C&v METHODS
}@3Ud'
Y Study population
AM>Yj Details about the study methodology for the Visual
k)?,xY\AV Impairment Project have been published previously.11
RY>)eGJ Briefly, cluster sampling within three strata was employed to
D+bB G recruit subjects aged 40 years and over to participate.
_<u8%\ Within the Melbourne Statistical Division, nine pairs of
uPa/,"p census collector districts were randomly selected. Fourteen
!7e
i1 nursing homes within a 5 km radius of these nine test sites
+AE&GU were randomly chosen to recruit nursing home residents.
X=rc3~}f Clinical and Experimental Ophthalmology (2000) 28, 77–82
`,F&y{A Original Article
BNAguAxWo Operated and unoperated cataract in Australia
1x~%Ydy Catherine A McCarty PhD, MPH, Mukesh B Nanjan PhD, Hugh R Taylor MD
)e4WAlg8c Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
v7s] n Correspondence: Dr Cathy McCarty MPH, Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, 32 Gisborne Street, East Melbourne,
Y|{r
vBKjf Victoria 3002, Australia. Email:
cathy@cera.unimelb.edu.au *(?U 78 McCarty et al.
@4 zi]
v Finally, four pairs of census collector districts in four rural
Z!C`f/h9 Victorian communities were randomly selected to recruit rural
^CowJ(y( residents. A household census was conducted to identify
F/Rng'l eligible residents aged 40 years and over who had been a
{0NsDi>(2 resident at that address for at least 6 months. At the time of
,!o\),N the household census, basic information about age, sex,
k| _$R? country of birth, language spoken at home, education, use of
ua]\xBWx corrective spectacles and use of eye care services was collected.
9f\aoVX Eligible residents were then invited to attend a local
)LXoey!aZ examination site for a more detailed interview and examination.
N0y;PVAGu The study protocol was approved by the Royal Victorian
u)q2YLK8 Eye and Ear Hospital Human Research Ethics Committee.
#~bU}[
{ Assessment of cataract
9IS1.3 A standardized ophthalmic examination was performed after
{pcf;1^t pupil dilatation with one drop of 10% phenylephrine
|'V<>v.v hydrochloride. Lens opacities were graded clinically at the
<GL}1W"Ay time of the examination and subsequently from photos using
)0Y #-=.< the Wilmer cataract photo-grading system.12 Cortical and
2]of SdM posterior subcapsular (PSC) opacities were assessed on
kcq9p2zKv retroillumination and measured as the proportion (in 1/16)
Bo](n*i of pupil circumference occupied by opacity. For this analysis,
i#pjv'C cortical cataract was defined as 4/16 or greater opacity,
WL
IDw@fv PSC cataract was defined as opacity equal to or greater than
EuKrYY]
g 1 mm2 and nuclear cataract was defined as opacity equal to
X7XCZSh#A or greater than Wilmer standard 2,12 independent of visual
_Ep{|]:gw acuity. Examples of the minimum opacities defined as cortical,
({d,oU$>y nuclear and PSC cataract are presented in Figure 1.
j:rs+1bc Bilateral congenital cataracts or cataracts secondary to
Y0P}KPD intraocular inflammation or trauma were excluded from the
~cO?S2!W analysis. Two cases of bilateral secondary cataract and eight
(]zl$*k cases of bilateral congenital cataract were excluded from the
N27K analyses.
dyQ<UT A Topcon® SL5 photo slit-lamp (Topcon America Corp.,
haEZp6Z Paramus, NJ, USA) with a 0.1 mm slit beam of 9.0 mm in
G:h;C].
height set to an incident angle of 30° was used for examinations.
]HNT(w@ Ektachrome® 200 ASA colour slide film (Eastman
}2iKi(io* Kodak Company, Rochester, NY, USA) was used to photograph
P\*2c*,W; the nuclear opacities. The cortical opacities were
WV,?Ge
photographed with an Oxford® retroillumination camera
$+!}Vtb (Marcher Enterprises Ltd, Hereford, UK) and T-MAX® 400
d!}jdt5% film (Eastman Kodak). Photographs were graded separately
&dZ.+#8r by two research assistants and discrepancies were adjudicated
UijuJ(Tle by an independent reviewer. Any discrepancies
|(J
?#? between the clinical grades and the photograph grades were
uusY,Dt/9 resolved. Except in cases where photographs were missing,
.swgXiRvs the photograph grades were used in the analyses. Photograph
~u?x{[ grades were available for 4301 (84%) for cortical
DMK"Q#Vw cataract, 4147 (81%) for nuclear cataract and 4303 (84%)
nL7S3 for PSC cataract. Cataract status was classified according to
4Rrw8Bw the severity of the opacity in the worse eye.
*FLT
z(T Assessment of risk factors
2t]! {L A standardized questionnaire was used to obtain information
v:J.d5 about education, employment and ethnic background.11
%`s9yRk9>E Specific information was elicited on the occurrence, duration
e%@[d<Ta\ and treatment of a number of medical conditions,
O'&X aaZV including ocular trauma, arthritis, diabetes, gout, hypertension
qs8K jG@ and mental illness. Information about the use, dose and
COkLn)+0 duration of tobacco, alcohol, analgesics and steriods were
0o"<^]
_| collected, and a food frequency questionnaire was used to
X/;"CM determine current consumption of dietary sources of antioxidants
w=P<4bdT and use of vitamin supplements.
:hl}Zn~jt Data management and statistical analysis
HZr/0I? Data were collected either by direct computer entry with a
*{;A\sL questionnaire programmed in Paradox© (Carel Corporation,
!3X%5=#L4 Ottawa, Canada) with internal consistency checks, or
*> &N
t on self-coding forms. Open-ended responses were coded at
L/ICFa.G a later time. Data that were entered on the self-coded forms
?w5nKpG#RI were entered into a computer with double data entry and
=|{,5="
reconciliation of any inconsistencies. Data range and consistency
n
nnA, checks were performed on the entire data set.
82@;.% SAS© version 6.1 (SAS Institute, Cary, North Carolina) was
{;z
L[AgCg employed for statistical analyses.
z_,]fd=o Ninety-five per cent confidence limits around the agespecific
&_%+r5 rates were calculated according to Cochran13 to
rb
J)RN^. account for the effect of the cluster sampling. Ninety-five
$85o%siS' per cent confidence limits around age-standardized rates
YT 03>!B were calculated according to Breslow and Day.14 The strataspecific
nu<!2xs, data were weighted according to the 1996
Q]?J%P. Australian Bureau of Statistics census data15 to reflect the
,LPFb6o cataract prevalence in the entire Victorian population.
? Ge*~d Univariate analyses with Student’s t-tests and chi-squared
X)R]a]1A tests were first employed to evaluate risk factors for unoperated
g7Q*KA+ cataract. Any factors with P < 0.10 were then fitted
W 9:{pQG into a backwards stepwise logistic regression model. For the
2.&V Figure 1. Minimum levels of cortical (a), nuclear (b), and posterior subcapsular (c) cataract.
#y9K-}u final multivariate models, P < 0.05 was considered statistically
Ew,wNR` significant. Design effect was assessed through the use
AU?YZEAei of cluster-specific models and multivariate models. The
VflPNzixb! design effect was assumed to be additive and an adjustment
N4]6LA6x6 made in the variance by adding the variance associated with
PQ#-.K the design effect prior to constructing the 95% confidence
ib=^tK limits.
PH4bM RESULTS
IE
sD= Study population
9M~$W-5 A total of 3271 (83%) of the Melbourne residents, 403
x 3co? (90%) Melbourne nursing home residents, and 1473 (92%)
v5bb|o[{K rural residents participated. In general, non-participants did
3UtXxL&L` not differ from participants.16 The study population was
Ecl7=-y representative of the Victorian population and Australia as
V'h z1roe a whole.
m3!MHe~t The Melbourne residents ranged in age from 40 to
<^c0bY1 98 years (mean = 59) and 1511 (46%) were male. The
pC.P Melbourne nursing home residents ranged in age from 46 to
CpdY)SMSL 101 years (mean = 82) and 85 (21%) were men. The rural
q9z!g/,d/ residents ranged in age from 40 to 103 years (mean = 60)
&MLhCekY and 701 (47.5%) were men.
q'-l;
V| Prevalence of cataract and prior cataract surgery
LO*a>9LI As would be expected, the rate of any cataract increases
xfQ;5
n dramatically with age (Table 1). The weighted rate of any
;j\$[4W.i cataract in Victoria was 21.5% (95% CL 18.1, 24.9).
@%85k/( Although the rates varied somewhat between the three
4~MUc! strata, they were not significantly different as the 95% confidence
1ucUnNkcV limits overlapped. The per cent of cataractous eyes
n/Z =q?_ with best-corrected visual acuity of less than 6/12 was 12.5%
&I_!&m~ (65/520) for cortical cataract, 18% for nuclear cataract
@!HMd{r (97/534) and 14.4% (27/187) for PSC cataract. Cataract
I,Y^_(JW surgery also rose dramatically with age. The overall
=U|SK"oO weighted rate of prior cataract surgery in Victoria was
v"TH[}C9D 3.79% (95% CL 2.97, 4.60) (Table 2).
-+Ji~;b Risk factors for unoperated cataract
#`wfl9tj Cases of cataract that had not been removed were classified
iEO2Bil] as unoperated cataract. Risk factor analyses for unoperated
#yxYL0CcA: cataract were not performed with the nursing home residents
pl/$@K?L as information about risk factor exposure was not
SvrV5X available for this cohort. The following factors were assessed
56aJE
.?< in relation to unoperated cataract: age, sex, residence
"2j~3aWj (urban/rural), language spoken at home (a measure of ethnic
*M5C*}dl integration), country of birth, parents’ country of birth (a
45JLx?rN_ measure of ethnicity), years since migration, education, use
HYa!$P3}[ of ophthalmic services, use of optometric services, private
A|nU
_* health insurance status, duration of distance glasses use,
EU~'n- glaucoma, age-related maculopathy and employment status.
\dbtdhT;Z In this cross sectional study it was not possible to assess the
N=x,96CF level of visual acuity that would predict a patient’s having
j* ja
) cataract surgery, as visual acuity data prior to cataract
hZG{"O!2s surgery were not available.
ZXkAw sr The significant risk factors for unoperated cataract in univariate
^el:)$ analyses were related to: whether a participant had
^jC0S[csw2 ever seen an optometrist, seen an ophthalmologist or been
AIo;\35 diagnosed with glaucoma; and participants’ employment
k{8N@&D status (currently employed) and age. These significant
Etk<`GRfA factors were placed in a backwards stepwise logistic regression
|a3b2x, model. The factors that remained significantly related
Yq.@7cJ to unoperated cataract were whether participants had ever
H[oi? {L seen an ophthalmologist, seen an optometrist and been
O;tn5 diagnosed with glaucoma. None of the demographic factors
]t<%>Z$ were associated with unoperated cataract in the multivariate
IHfqW? model.
v]sGdZ(6- The per cent of participants with unoperated cataract
dD!SgK [Jv who said that they were dissatisfied or very dissatisfied with
c Ix(;[U Operated and unoperated cataract in Australia 79
Su~`jRN$ Table 1. Prevalence of any cataracta (excluding previous cataract surgery) by age, gender and cohort
!Zx>)V6. Age group Sex Urban Rural Nursing home Weighted total
\:S8mDI^s (years) (%) (%) (%)
6<R
U~Gh 40–49 Male 2.56 4.04 0.00 3.00 (1.91, 4.08)
2Ev,dWV Female 2.61 1.70 0.00 2.36 (1.61, 3.10)
co|0s+%PBq 50–59 Male 7.69 6.94 0.00 7.47 (5.80, 9.15)
#{a <{HX Female 6.67 7.56 0.00 6.92 (5.60, 8.24)
s,=^V/c 60–69 Male 20.7 25.0 10.0 22.0 (18.1, 26.0)
)c_ll;% Female 27.9 35.7 37.5 30.3 (26.0, 34.7)
sy?W\(x 70–79 Male 43.1 58.7 39.1 48.1 (41.2, 55.1)
#t*c*o Female 58.6 66.2 55.6 61.0 (56.0, 65.9)
~f:fOrLE# 80–89 Male 74.0 89.3 92.0 79.3 (72.3, 86.3)
"k/x+%!Spc Female 91.9 97.0 80.2 92.6 (86.4, 98.8)
r}w 9?s^rB 90 + Male 100.0 100.0 75.0 98.8 (96.2, 100.0)
ZBWe,Xvq Female 100.0 100.0 93.8 98.6 (97.0, 100.0)
bBf+z7iyc Age-standardized
Gy5W;,$q (95% CL) Combined 19.7 (16.3, 23.1) 23.2 (16.1, 30.2) 16.5 (2.06, 30.9) 21.5 (18.1, 25.0)
g$qh(Z_s aCortical > 4/16, nuclear > standard 2, posterior subcapsular > 1 mm2
/WMLr5 their current vision was 30% (290/683), compared with 27%
0ni5 :t
Yy (26/95) of participants with prior cataract surgery (chisquared,
[S% 1 d.f. = 0.25, P = 0.62).
~a}pYLxl Outcomes of cataract surgery
}\ F>z Two hundred and forty-nine eyes had undergone prior
d>}%A
] cataract surgery. Of these 249 operated eyes, 49 (20%) were
:>;#/<3{ left aphakic, 6 (2.4%) had anterior chamber intraocular
>_". lenses and 194 (78%) had posterior chamber intraocular
b< rM3P; lenses. The rate of capsulotomy in the eyes with intact
W~qo
`r posterior capsules was 36% (73/202). Fifteen per cent of
:zCm$@ eyes (17/114) with a clear posterior capsule had bestcorrected
a]*^uEs visual acuity of less than 6/12 compared with 43%
S70ERRk of eyes (6/14) with opaque capsules, and 15% of eyes
@UA>6F (11/73) with prior capsulotomies (chi-squared, 2 d.f. = 7.21,
9o6y7hEQy P = 0.027).
8CL05:& The percentage of eyes with best-corrected visual acuity
9f
"*Oj of 6/12 or better was 96% (302/314) for eyes without
6\bbP>ql cataract, 88% (1417/1609) for eyes with prevalent cataract
AxeWj%w@ and 85% (211/249) for eyes with operated cataract (chisquared,
>wn&+%i& 2 d.f. = 22.3), P < 0.001). Twenty-seven of the
$]vR ,E operated eyes (11%) had visual acuities of less than 6/18
a7Jr} "B (moderate vision impairment) (Fig. 2). A cause of this
&sW/r::, moderate visual impairment (but not the only cause) in four
Vo\d&}Q (15%) eyes was secondary to cataract surgery. Three of these
q
&+GpR four eyes had undergone intracapsular cataract extraction
yP@=x!$ and the fourth eye had an opaque posterior capsule. No one
lIf Our had bilateral vision impairment as a result of their cataract
qIk6S6 surgery.
:KFhryN DISCUSSION
3K'3Xp@A To our knowledge, this is the first paper to systematically
c/s'&gG33z assess the prevalence of current cataract, previous cataract
au8)G_A surgery, predictors of unoperated cataract and the outcomes
H;^6%HV1 of cataract surgery in a population-based sample. The Visual
A4#m&o