ABSTRACT
w~)tEN> Purpose: To quantify the prevalence of cataract, the outcomes
-f&vH_eK of cataract surgery and the factors related to
JR#4{P@A unoperated cataract in Australia.
R%RxF=@ Methods: Participants were recruited from the Visual
#p@GhI!6 Impairment Project: a cluster, stratified sample of more than
{%G9iOV. 5000 Victorians aged 40 years and over. At examination
e|!' sites interviews, clinical examinations and lens photography
dh7`eAMY were performed. Cataract was defined in participants who
M%`CzCL
u had: had previous cataract surgery, cortical cataract greater
3?a`@C&x than 4/16, nuclear greater than Wilmer standard 2, or
IZj`*M%3 posterior subcapsular greater than 1 mm2.
`!Z?F]):G Results: The participant group comprised 3271 Melbourne
@6yc^DAA residents, 403 Melbourne nursing home residents and 1473
>-I <`y-H rural residents.The weighted rate of any cataract in Victoria
63Zu5b"O/ was 21.5%. The overall weighted rate of prior cataract
[w'Q9\,p surgery was 3.79%. Two hundred and forty-nine eyes had
|qn2b= had prior cataract surgery. Of these 249 procedures, 49
dgpE3
37Lt (20%) were aphakic, 6 (2.4%) had anterior chamber
hJ{u!:4 intraocular lenses and 194 (78%) had posterior chamber
L T$U
z intraocular lenses.Two hundred and eleven of these operated
H9(?yI@Zr# eyes (85%) had best-corrected visual acuity of 6/12 or
5q0L<GOrj better, the legal requirement for a driver’s license.Twentyseven
q-<DYVG+ (11%) had visual acuity of less than 6/18 (moderate
B>L7UQ6_[ vision impairment). Complications of cataract surgery
8<C*D".T$ caused reduced vision in four of the 27 eyes (15%), or 1.9%
]!/U9"_e"B of operated eyes. Three of these four eyes had undergone
BI`)P+K2 intracapsular cataract extraction and the fourth eye had an
@vlP)" opaque posterior capsule. No one had bilateral vision
M(I%y
0 impairment as a result of cataract surgery. Surprisingly, no
.kBkYK8*t particular demographic factors (such as age, gender, rural
src9EeiV residence, occupation, employment status, health insurance
-"I$$C status, ethnicity) were related to the presence of unoperated
s-"KABEE cataract.
:VT%d{Vp_ Conclusions: Although the overall prevalence of cataract is
"u^Erj# / quite high, no particular subgroup is systematically underserviced
,j*9 ) in terms of cataract surgery. Overall, the results of
xvOz*vM? cataract surgery are very good, with the majority of eyes
f7_(C0d achieving driving vision following cataract extraction.
RTc@`m3 M Key words: cataract extraction, health planning, health
dun`/QKV services accessibility, prevalence
r/sSkF F INTRODUCTION
|jiIx5qr Cataract is the leading cause of blindness worldwide and, in
6'^E
],:b Australia, cataract extractions account for the majority of all
+c~&o83[ ophthalmic procedures.1 Over the period 1985–94, the rate
w#b@6d of cataract surgery in Australia was twice as high as would be
QR&e~rks expected from the growth in the elderly population.1
"/zgh Although there have been a number of studies reporting
ZHNL~=r}
the prevalence of cataract in various populations,2–6 there is
v.(dOIrX little information about determinants of cataract surgery in
gq?7O< the population. A previous survey of Australian ophthalmologists
r84^/+"T showed that patient concern and lifestyle, rather
[Qnf]n\FJ than visual acuity itself, are the primary factors for referral
%V>%AP for cataract surgery.7 This supports prior research which has
}MQ:n8
shown that visual acuity is not a strong predictor of need for
]6e(-v!U cataract surgery.8,9 Elsewhere, socioeconomic status has
T01Iu been shown to be related to cataract surgery rates.10
FoetP`
To appropriately plan health care services, information is
]CzK{-W needed about the prevalence of age-related cataract in the
OyO]; Yk community as well as the factors associated with cataract
y >=Y surgery. The purpose of this study is to quantify the prevalence
w^0hVrws=, of any cataract in Australia, to describe the factors
iAz0 A related to unoperated cataract in the community and to
IAQ<|3Q describe the visual outcomes of cataract surgery.
zP44
Xhz METHODS
86=W}eV1r Study population
MDF_Xr-hZ Details about the study methodology for the Visual
86{>X5 + Impairment Project have been published previously.11
I;w! Briefly, cluster sampling within three strata was employed to
p-iFe\+ recruit subjects aged 40 years and over to participate.
(X "J)xaQ Within the Melbourne Statistical Division, nine pairs of
?>B?*IK! census collector districts were randomly selected. Fourteen
c]uieig0~ nursing homes within a 5 km radius of these nine test sites
'JOCL0FP were randomly chosen to recruit nursing home residents.
"B{3q`( Clinical and Experimental Ophthalmology (2000) 28, 77–82
gk|>E[. Original Article
0I.KHIBk Operated and unoperated cataract in Australia
Kzrd<h]`) Catherine A McCarty PhD, MPH, Mukesh B Nanjan PhD, Hugh R Taylor MD
Po)U!5Tm Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
7*P
BJt\ n Correspondence: Dr Cathy McCarty MPH, Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, 32 Gisborne Street, East Melbourne,
<J<"`xKL Victoria 3002, Australia. Email:
cathy@cera.unimelb.edu.au sbmtx/%U 78 McCarty et al.
KyNu8s k Finally, four pairs of census collector districts in four rural
He=C\" Victorian communities were randomly selected to recruit rural
f5*qlQJFz\ residents. A household census was conducted to identify
Q#3}AO eligible residents aged 40 years and over who had been a
NVx>^5QV
resident at that address for at least 6 months. At the time of
b#?sx"z the household census, basic information about age, sex,
~-k,$J?7 country of birth, language spoken at home, education, use of
P*!`AWn corrective spectacles and use of eye care services was collected.
IVPN=jg? Eligible residents were then invited to attend a local
C4(xtSJSd! examination site for a more detailed interview and examination.
;D~#|CB The study protocol was approved by the Royal Victorian
:6(\: Eye and Ear Hospital Human Research Ethics Committee.
BSMb(EnqX Assessment of cataract
b[:,p?:@ A standardized ophthalmic examination was performed after
_6fy'%J=U pupil dilatation with one drop of 10% phenylephrine
n5C,Z!)z hydrochloride. Lens opacities were graded clinically at the
KyrZ&E.` time of the examination and subsequently from photos using
~TH4='4W3 the Wilmer cataract photo-grading system.12 Cortical and
n>pJ/l%` posterior subcapsular (PSC) opacities were assessed on
LN+x!#:e retroillumination and measured as the proportion (in 1/16)
u)Kiwa of pupil circumference occupied by opacity. For this analysis,
1av#u:jy~> cortical cataract was defined as 4/16 or greater opacity,
zV}:~;w PSC cataract was defined as opacity equal to or greater than
((`\i=-o5 1 mm2 and nuclear cataract was defined as opacity equal to
K9ia|2f or greater than Wilmer standard 2,12 independent of visual
e'uC:O.u acuity. Examples of the minimum opacities defined as cortical,
3:xx:Jt nuclear and PSC cataract are presented in Figure 1.
lZRO"[< Bilateral congenital cataracts or cataracts secondary to
k~AtnI intraocular inflammation or trauma were excluded from the
h;vY=r- analysis. Two cases of bilateral secondary cataract and eight
Ud+,/pE>FA cases of bilateral congenital cataract were excluded from the
oH17!$Fly analyses.
.f0qgmIyL A Topcon® SL5 photo slit-lamp (Topcon America Corp.,
;@k=9o]A Paramus, NJ, USA) with a 0.1 mm slit beam of 9.0 mm in
5 ph CEKt; height set to an incident angle of 30° was used for examinations.
6h5g!GQD Ektachrome® 200 ASA colour slide film (Eastman
ShL!7y*rT{ Kodak Company, Rochester, NY, USA) was used to photograph
R\ 8[6H the nuclear opacities. The cortical opacities were
.lj5pmD photographed with an Oxford® retroillumination camera
xO:h
[ (Marcher Enterprises Ltd, Hereford, UK) and T-MAX® 400
rb@[Edj film (Eastman Kodak). Photographs were graded separately
!G vT
{ by two research assistants and discrepancies were adjudicated
DcFY b|p by an independent reviewer. Any discrepancies
2He R1m< between the clinical grades and the photograph grades were
>lM/\HO2 resolved. Except in cases where photographs were missing,
SVwxK/Fci the photograph grades were used in the analyses. Photograph
,7cw%mQA grades were available for 4301 (84%) for cortical
*
G*VY#L cataract, 4147 (81%) for nuclear cataract and 4303 (84%)
a ub$4n!C9 for PSC cataract. Cataract status was classified according to
[ <d~b*/ the severity of the opacity in the worse eye.
KM)MUPr Assessment of risk factors
0TV16-- A standardized questionnaire was used to obtain information
p q?# X0 about education, employment and ethnic background.11
m;"[b (u Specific information was elicited on the occurrence, duration
%!-t7K^mFq and treatment of a number of medical conditions,
Ux?G:LLz including ocular trauma, arthritis, diabetes, gout, hypertension
c8]%,26. and mental illness. Information about the use, dose and
c)Ef]E\ duration of tobacco, alcohol, analgesics and steriods were
.$d:c61X collected, and a food frequency questionnaire was used to
SF:{PgGMi determine current consumption of dietary sources of antioxidants
[-#1;!k and use of vitamin supplements.
:#sBNy Data management and statistical analysis
WSeiW Data were collected either by direct computer entry with a
aH%tD!%,o questionnaire programmed in Paradox© (Carel Corporation,
sX>|Y3S\U Ottawa, Canada) with internal consistency checks, or
7 v3%dCvf on self-coding forms. Open-ended responses were coded at
GRL42xp'*D a later time. Data that were entered on the self-coded forms
A ?~4Pe were entered into a computer with double data entry and
:+^`VLIf reconciliation of any inconsistencies. Data range and consistency
MD1d checks were performed on the entire data set.
|M<R{Tt}nf SAS© version 6.1 (SAS Institute, Cary, North Carolina) was
WV|9d}5 employed for statistical analyses.
RvVF^~u Ninety-five per cent confidence limits around the agespecific
xU.Ymq& 5 rates were calculated according to Cochran13 to
M
S|1Q@S9 account for the effect of the cluster sampling. Ninety-five
}?GeU
Xhy per cent confidence limits around age-standardized rates
N9F
u were calculated according to Breslow and Day.14 The strataspecific
7V\M)r{q7 data were weighted according to the 1996
Q6X}R,KA1 Australian Bureau of Statistics census data15 to reflect the
aJNsJIY+ cataract prevalence in the entire Victorian population.
.W-=V zWX Univariate analyses with Student’s t-tests and chi-squared
+w3k_^X9c tests were first employed to evaluate risk factors for unoperated
|TBKsx8 cataract. Any factors with P < 0.10 were then fitted
)i.\q into a backwards stepwise logistic regression model. For the
`p^xdj} Figure 1. Minimum levels of cortical (a), nuclear (b), and posterior subcapsular (c) cataract.
f%d
=X>_ final multivariate models, P < 0.05 was considered statistically
^yF2xJ)9- significant. Design effect was assessed through the use
Lr(wS { of cluster-specific models and multivariate models. The
j\@|
oW0 design effect was assumed to be additive and an adjustment
QNm.8c$ made in the variance by adding the variance associated with
Sh5SOYLz the design effect prior to constructing the 95% confidence
J
9k~cz limits.
le`_ RESULTS
x~O_v Study population
9ev"BO A total of 3271 (83%) of the Melbourne residents, 403
V$ss[fX (90%) Melbourne nursing home residents, and 1473 (92%)
v:]
AS: rural residents participated. In general, non-participants did
1G+?/w not differ from participants.16 The study population was
?_c*(2i&^ representative of the Victorian population and Australia as
3~!PJI1 a whole.
gobqS+c The Melbourne residents ranged in age from 40 to
@=[SsS 98 years (mean = 59) and 1511 (46%) were male. The
_7zER6#} Melbourne nursing home residents ranged in age from 46 to
MoP0qNk 101 years (mean = 82) and 85 (21%) were men. The rural
/\9X0a2h|E residents ranged in age from 40 to 103 years (mean = 60)
az]S&\i7T and 701 (47.5%) were men.
DNaU
mz Prevalence of cataract and prior cataract surgery
o5FBqt As would be expected, the rate of any cataract increases
"syf@[tz7 dramatically with age (Table 1). The weighted rate of any
b|*A%?m cataract in Victoria was 21.5% (95% CL 18.1, 24.9).
xCV3HnZ Although the rates varied somewhat between the three
,9f$a
n strata, they were not significantly different as the 95% confidence
(k..ll p~ limits overlapped. The per cent of cataractous eyes
xla9:*pPn with best-corrected visual acuity of less than 6/12 was 12.5%
}cE,&n (65/520) for cortical cataract, 18% for nuclear cataract
ET`;Tfq
M (97/534) and 14.4% (27/187) for PSC cataract. Cataract
Rd5r~iT surgery also rose dramatically with age. The overall
>w?O?&Q$ weighted rate of prior cataract surgery in Victoria was
&Fl^&&1C 3.79% (95% CL 2.97, 4.60) (Table 2).
4y+]V~p Risk factors for unoperated cataract
:(Feg 2c Cases of cataract that had not been removed were classified
CV4r31w as unoperated cataract. Risk factor analyses for unoperated
'wX'}3_/g cataract were not performed with the nursing home residents
!\8j[QS! as information about risk factor exposure was not
8KW}XG available for this cohort. The following factors were assessed
ewk62{ in relation to unoperated cataract: age, sex, residence
g R(*lXm5w (urban/rural), language spoken at home (a measure of ethnic
Sj}@5 X6 C integration), country of birth, parents’ country of birth (a
R {+Rvk measure of ethnicity), years since migration, education, use
VWmZ|9Ri of ophthalmic services, use of optometric services, private
c% 0h!zF health insurance status, duration of distance glasses use,
Y'Jb@l`$- glaucoma, age-related maculopathy and employment status.
VD.p"F(] In this cross sectional study it was not possible to assess the
%"DEgIP level of visual acuity that would predict a patient’s having
>OwVNG cataract surgery, as visual acuity data prior to cataract
~c`@uGw surgery were not available.
=[?2'riI The significant risk factors for unoperated cataract in univariate
zpIl'/i analyses were related to: whether a participant had
%dS7u$Rnh ever seen an optometrist, seen an ophthalmologist or been
.7Ys@;>B diagnosed with glaucoma; and participants’ employment
QM9~O#rL status (currently employed) and age. These significant
fh
)QX factors were placed in a backwards stepwise logistic regression
T2}I,{U model. The factors that remained significantly related
7~eo^/PbS to unoperated cataract were whether participants had ever
brNe13d3~" seen an ophthalmologist, seen an optometrist and been
z>
&Py( diagnosed with glaucoma. None of the demographic factors
X!CLOHVAa were associated with unoperated cataract in the multivariate
Cr4shdN34 model.
^;NM'Z The per cent of participants with unoperated cataract
R/b)h P~ who said that they were dissatisfied or very dissatisfied with
C\.? 3 Operated and unoperated cataract in Australia 79
:I F&W=?9 Table 1. Prevalence of any cataracta (excluding previous cataract surgery) by age, gender and cohort
A!<R? Age group Sex Urban Rural Nursing home Weighted total
gUL`)t\} * (years) (%) (%) (%)
phl5E:fIKx 40–49 Male 2.56 4.04 0.00 3.00 (1.91, 4.08)
6H VS0 Female 2.61 1.70 0.00 2.36 (1.61, 3.10)
|j^>6nE 50–59 Male 7.69 6.94 0.00 7.47 (5.80, 9.15)
emw
3cQ Female 6.67 7.56 0.00 6.92 (5.60, 8.24)
g*-
K!X6l 60–69 Male 20.7 25.0 10.0 22.0 (18.1, 26.0)
&]pW## Female 27.9 35.7 37.5 30.3 (26.0, 34.7)
_9#4 70–79 Male 43.1 58.7 39.1 48.1 (41.2, 55.1)
:8E(pq|1PB Female 58.6 66.2 55.6 61.0 (56.0, 65.9)
:5U(}\dL
{ 80–89 Male 74.0 89.3 92.0 79.3 (72.3, 86.3)
3UD_2[aqN( Female 91.9 97.0 80.2 92.6 (86.4, 98.8)
~e~4S~{ 90 + Male 100.0 100.0 75.0 98.8 (96.2, 100.0)
#2_phm' Female 100.0 100.0 93.8 98.6 (97.0, 100.0)
R7ZxS Age-standardized
8$OE<c?#5n (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)
46Nl];g1` aCortical > 4/16, nuclear > standard 2, posterior subcapsular > 1 mm2
Sw%=/ g their current vision was 30% (290/683), compared with 27%
}4#%0x`w (26/95) of participants with prior cataract surgery (chisquared,
=MB[v/M59w 1 d.f. = 0.25, P = 0.62).
y*vs}G'W Outcomes of cataract surgery
$w)yQ % Two hundred and forty-nine eyes had undergone prior
+QtK
"5M
cataract surgery. Of these 249 operated eyes, 49 (20%) were
rzLpVpTaz left aphakic, 6 (2.4%) had anterior chamber intraocular
Ad9'q!_en lenses and 194 (78%) had posterior chamber intraocular
f lR6^6E lenses. The rate of capsulotomy in the eyes with intact
?\(E+6tpP posterior capsules was 36% (73/202). Fifteen per cent of
]A5FN4 E eyes (17/114) with a clear posterior capsule had bestcorrected
x`WP*a7Fk] visual acuity of less than 6/12 compared with 43%
.,
o=# of eyes (6/14) with opaque capsules, and 15% of eyes
"n}J6 (11/73) with prior capsulotomies (chi-squared, 2 d.f. = 7.21,
:+bQPzL P = 0.027).
c/^}
=t( The percentage of eyes with best-corrected visual acuity
%qV=PC of 6/12 or better was 96% (302/314) for eyes without
vCb3Ra~L` cataract, 88% (1417/1609) for eyes with prevalent cataract
#OqQD6 and 85% (211/249) for eyes with operated cataract (chisquared,
Z[)t34EY" 2 d.f. = 22.3), P < 0.001). Twenty-seven of the
~-.}]N+([ operated eyes (11%) had visual acuities of less than 6/18
5@%$M$E (moderate vision impairment) (Fig. 2). A cause of this
Nv,1
F moderate visual impairment (but not the only cause) in four
}TzMWdT (15%) eyes was secondary to cataract surgery. Three of these
yH|[K=?S[ four eyes had undergone intracapsular cataract extraction
(+`pEDD{X and the fourth eye had an opaque posterior capsule. No one
LBq~?Q.e had bilateral vision impairment as a result of their cataract
qjFz}6 surgery.
\T`InBbf DISCUSSION
VCSHq&p8 To our knowledge, this is the first paper to systematically
J3fk3d`2 assess the prevalence of current cataract, previous cataract
Jr$,w7tQn@ surgery, predictors of unoperated cataract and the outcomes
m\o<a| of cataract surgery in a population-based sample. The Visual
9 js!gJC Impairment Project is unique in that the sampling frame and
a"SH_+T{ high response rate have ensured that the study population is
H=Scrvfx representative of Australians aged 40 years and over. Therefore,
a\;1%2a these data can be used to plan age-related cataract
3#N'nhUzA services throughout Australia.
a~q_2S]h We found the rate of any cataract in those over the age
GKT2x '(e of 40 years to be 22%. Although relatively high, this rate is
;wo significantly less than was reported in a number of previous
.1n=&d| studies,2,4,6 with the exception of the Casteldaccia Eye
"yaz!?O>
Study.5 However, it is difficult to compare rates of cataract
Y-!~x0-H between studies because of different methodologies and
Hdvtgss! cataract definitions employed in the various studies, as well
;iT@41)7 as the different age structures of the study populations.
KuBN_bd Other studies have used less conservative definitions of
.#^ta9^t7 cataract, thus leading to higher rates of cataract as defined.
0lpkG
="&r In most large epidemiologic studies of cataract, visual acuity
mJ+M|#Ox has not been included in the definition of cataract.
aQ!QrTua- Therefore, the prevalence of cataract may not reflect the
=MR.*m{ actual need for cataract surgery in the community.
6
/-] 80 McCarty et al.
l5h+:^#M5c Table 2. Prevalence of previous cataract by age, gender and cohort
?'_Ty`vT Age group Gender Urban Rural Nursing home Weighted total
cp1-eR_& (years) (%) (%) (%)
F}1h 40–49 Male 1.14 0.00 0.00 0.80 (0.00, 1.81)
8Z&M}Llk Female 0.00 0.00 0.00 0.00 (
*y+N-uq 50–59 Male 0.68 0.58 0.00 0.65 (0.13, 1.17)
1`hmD1d Female 0.57 0.00 0.00 0.41 (0.00, 1.00)
yMG(FAyu 60–69 Male 2.12 7.59 0.00 3.80 (1.41, 6.19)
./]xn Female 2.11 3.51 0.00 2.54 (1.81, 3.26)
:g%hT$,]3b 70–79 Male 8.22 9.85 8.70 8.75 (6.38, 11.1)
mkE_ a> Female 7.21 7.86 7.02 7.41 (5.36, 9.46)
1NAGGr00 80–89 Male 25.0 30.0 14.3 26.2 (17.0, 35.4)
"D\>oFu Female 27.9 25.6 18.3 26.7 (20.2, 33.3)
1d$qr`
90 + Male 0.00 16.7 66.7 9.19 (0.00, 21.5)
2jf73$F Female 58.3 100.0 26.9 63.1 (44.4, 81.8)
uTShz
3 Age-standardized
sYEh>%mo^C (95% CL) Combined 3.31 (2.70, 3.93) 4.36 (2.67, 6.06) 2.26 (0.82, 3.70) 3.79 (2.97, 4.60)
\gsJ1@ Figure 2. Visual acuity in eyes that had undergone cataract
3S 5`I9I surgery, n = 249. h, Presenting; j, best-corrected.
dhX$b!DA Operated and unoperated cataract in Australia 81
O~Jm<