ABSTRACT
Ig6>+Mw Purpose: To quantify the prevalence of cataract, the outcomes
R0*+GIRA( of cataract surgery and the factors related to
DeTZl+qm1E unoperated cataract in Australia.
RU'DUf Methods: Participants were recruited from the Visual
kV Z5>D$ Impairment Project: a cluster, stratified sample of more than
@Q atgYu 5000 Victorians aged 40 years and over. At examination
7a:mZ[Vh sites interviews, clinical examinations and lens photography
xbA% 'p were performed. Cataract was defined in participants who
{G%!M+n< had: had previous cataract surgery, cortical cataract greater
~f2zMTI| than 4/16, nuclear greater than Wilmer standard 2, or
:{tvAdMl7 posterior subcapsular greater than 1 mm2.
N{G+|WmQ Results: The participant group comprised 3271 Melbourne
eMvb*X6 residents, 403 Melbourne nursing home residents and 1473
<`q|6XWL rural residents.The weighted rate of any cataract in Victoria
tnmuCz was 21.5%. The overall weighted rate of prior cataract
wQ,RZO3 surgery was 3.79%. Two hundred and forty-nine eyes had
VPTT*a` had prior cataract surgery. Of these 249 procedures, 49
0ZV)Y<DJ (20%) were aphakic, 6 (2.4%) had anterior chamber
FZ/l
T
-" intraocular lenses and 194 (78%) had posterior chamber
?fEX&t,' intraocular lenses.Two hundred and eleven of these operated
[hS?d.D eyes (85%) had best-corrected visual acuity of 6/12 or
s%z'1KPS better, the legal requirement for a driver’s license.Twentyseven
E `)p,{T (11%) had visual acuity of less than 6/18 (moderate
y=\jQ6Fc vision impairment). Complications of cataract surgery
!DCJ2h%E[_ caused reduced vision in four of the 27 eyes (15%), or 1.9%
u
hP0Zwn of operated eyes. Three of these four eyes had undergone
>{4pEy intracapsular cataract extraction and the fourth eye had an
LZG^\c$ opaque posterior capsule. No one had bilateral vision
XI\aZ\v impairment as a result of cataract surgery. Surprisingly, no
9VN
@
M particular demographic factors (such as age, gender, rural
Prhq ~oI4 residence, occupation, employment status, health insurance
c`X'Q)c&K status, ethnicity) were related to the presence of unoperated
g#_?Vxt cataract.
),\>'{~5& Conclusions: Although the overall prevalence of cataract is
Oyq<y~} quite high, no particular subgroup is systematically underserviced
u ?g!E."v in terms of cataract surgery. Overall, the results of
J5Fg]O* cataract surgery are very good, with the majority of eyes
=pcj{B{qa achieving driving vision following cataract extraction.
d!KX.K\NM, Key words: cataract extraction, health planning, health
(4 {49b services accessibility, prevalence
AD?DIE(v INTRODUCTION
/2dK*v0
Cataract is the leading cause of blindness worldwide and, in
f/;\/Q[Z7 Australia, cataract extractions account for the majority of all
+H&_Z38n ophthalmic procedures.1 Over the period 1985–94, the rate
+X*`}-3 of cataract surgery in Australia was twice as high as would be
GYO\l.%V5y expected from the growth in the elderly population.1
HqXo;`Yy} Although there have been a number of studies reporting
FOk @W& the prevalence of cataract in various populations,2–6 there is
RaU.yCYyu little information about determinants of cataract surgery in
X^|oY]D the population. A previous survey of Australian ophthalmologists
0dcXgP showed that patient concern and lifestyle, rather
doR'=@ W than visual acuity itself, are the primary factors for referral
h{* O9O< for cataract surgery.7 This supports prior research which has
=(n'#mV shown that visual acuity is not a strong predictor of need for
Gr6ma*)y~t cataract surgery.8,9 Elsewhere, socioeconomic status has
+rT( been shown to be related to cataract surgery rates.10
_yWH\
5@ To appropriately plan health care services, information is
z}Z`kq+C needed about the prevalence of age-related cataract in the
hx^a&" community as well as the factors associated with cataract
\PLV]%3, surgery. The purpose of this study is to quantify the prevalence
<Y orQ> of any cataract in Australia, to describe the factors
<Y#R]gf1 related to unoperated cataract in the community and to
HQ
s)T describe the visual outcomes of cataract surgery.
Nr[Rp METHODS
zDl, bLiJ Study population
E
kL\~^ Details about the study methodology for the Visual
*b)b#p Impairment Project have been published previously.11
i52R,hz Briefly, cluster sampling within three strata was employed to
gNqV>p recruit subjects aged 40 years and over to participate.
WD\{Sdx:r Within the Melbourne Statistical Division, nine pairs of
{cv;S2 census collector districts were randomly selected. Fourteen
qXI30Yo#d nursing homes within a 5 km radius of these nine test sites
Yjl0Pz.q were randomly chosen to recruit nursing home residents.
5{g9Wh[ Clinical and Experimental Ophthalmology (2000) 28, 77–82
pMB=iS<E Original Article
p&4n3%(R@ Operated and unoperated cataract in Australia
f
oVD+\~Y Catherine A McCarty PhD, MPH, Mukesh B Nanjan PhD, Hugh R Taylor MD
>1~`tP Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
v$i%>tQ\ n Correspondence: Dr Cathy McCarty MPH, Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, 32 Gisborne Street, East Melbourne,
fv_wK_.
%: Victoria 3002, Australia. Email:
cathy@cera.unimelb.edu.au SNU
bY6 78 McCarty et al.
NNE,|
: Finally, four pairs of census collector districts in four rural
d8kwW!m+ Victorian communities were randomly selected to recruit rural
'&QT
}B residents. A household census was conducted to identify
)A0
&16< eligible residents aged 40 years and over who had been a
5lxq-E3 resident at that address for at least 6 months. At the time of
5 WppV3; the household census, basic information about age, sex,
FqsjuU@l country of birth, language spoken at home, education, use of
| q16%6q corrective spectacles and use of eye care services was collected.
b(q&}60 Eligible residents were then invited to attend a local
Kk9 8FI0] examination site for a more detailed interview and examination.
y:OywIi( The study protocol was approved by the Royal Victorian
ptv4v[gQ Eye and Ear Hospital Human Research Ethics Committee.
$cOD6Xr)d Assessment of cataract
:UcS$M1LE A standardized ophthalmic examination was performed after
c2\vG pupil dilatation with one drop of 10% phenylephrine
N#)VD\m hydrochloride. Lens opacities were graded clinically at the
NoAb}1uae time of the examination and subsequently from photos using
W79A4l< the Wilmer cataract photo-grading system.12 Cortical and
'B5J.Xe: posterior subcapsular (PSC) opacities were assessed on
p\_qHq\;j retroillumination and measured as the proportion (in 1/16)
4D8y b|o of pupil circumference occupied by opacity. For this analysis,
'HWgvmw( cortical cataract was defined as 4/16 or greater opacity,
2Ml2Ue-9 PSC cataract was defined as opacity equal to or greater than
A4Q)YY9~ 1 mm2 and nuclear cataract was defined as opacity equal to
:ZfUjqRE or greater than Wilmer standard 2,12 independent of visual
@
KPv&UB acuity. Examples of the minimum opacities defined as cortical,
'+I
2$xE nuclear and PSC cataract are presented in Figure 1.
LEngZ~sV/ Bilateral congenital cataracts or cataracts secondary to
To8v#.i intraocular inflammation or trauma were excluded from the
uP=_-ZUW analysis. Two cases of bilateral secondary cataract and eight
.(dmuV9 cases of bilateral congenital cataract were excluded from the
A Wh*<H analyses.
ROt0<^< A Topcon® SL5 photo slit-lamp (Topcon America Corp.,
7k t7^V< Paramus, NJ, USA) with a 0.1 mm slit beam of 9.0 mm in
:y-0qzD? height set to an incident angle of 30° was used for examinations.
VtzmY Ektachrome® 200 ASA colour slide film (Eastman
0"<;You Kodak Company, Rochester, NY, USA) was used to photograph
S[hJ{0V the nuclear opacities. The cortical opacities were
fpK0MS]=b photographed with an Oxford® retroillumination camera
d! QD vO (Marcher Enterprises Ltd, Hereford, UK) and T-MAX® 400
=Sb:<q+Q film (Eastman Kodak). Photographs were graded separately
-6~dJTm[t by two research assistants and discrepancies were adjudicated
$|cp;~ 1 by an independent reviewer. Any discrepancies
KG-k$glD between the clinical grades and the photograph grades were
H8<7# resolved. Except in cases where photographs were missing,
*L4]\wf the photograph grades were used in the analyses. Photograph
hKH$AEHEU} grades were available for 4301 (84%) for cortical
q:-]d0B+ cataract, 4147 (81%) for nuclear cataract and 4303 (84%)
w-'D*dOi for PSC cataract. Cataract status was classified according to
'e<HP Ni) the severity of the opacity in the worse eye.
S1az3VJI\ Assessment of risk factors
}* B qi7E> A standardized questionnaire was used to obtain information
PX69
about education, employment and ethnic background.11
j""y2c1 Specific information was elicited on the occurrence, duration
^iV`g?z and treatment of a number of medical conditions,
A
^4kYOe including ocular trauma, arthritis, diabetes, gout, hypertension
vNK`Y|u@ and mental illness. Information about the use, dose and
$&xuVBs duration of tobacco, alcohol, analgesics and steriods were
TJyH/C collected, and a food frequency questionnaire was used to
\2].|Mym determine current consumption of dietary sources of antioxidants
QWzOp\+ and use of vitamin supplements.
da9*9yN Data management and statistical analysis
`bZ2x@ Data were collected either by direct computer entry with a
409x!d~it questionnaire programmed in Paradox© (Carel Corporation,
#Cg}!38 Ottawa, Canada) with internal consistency checks, or
2xL!PR- on self-coding forms. Open-ended responses were coded at
oeu|/\+HW a later time. Data that were entered on the self-coded forms
{8!ZKlB were entered into a computer with double data entry and
hs!UX=x| reconciliation of any inconsistencies. Data range and consistency
&J lpA<^s; checks were performed on the entire data set.
gqP-E SAS© version 6.1 (SAS Institute, Cary, North Carolina) was
-~vl+L employed for statistical analyses.
C@TN5?Z Ninety-five per cent confidence limits around the agespecific
YM# rates were calculated according to Cochran13 to
97qtJ(ESI account for the effect of the cluster sampling. Ninety-five
)(:+q(m per cent confidence limits around age-standardized rates
L;1$xI8tx were calculated according to Breslow and Day.14 The strataspecific
sorSyuG
r data were weighted according to the 1996
tr6jh=
Australian Bureau of Statistics census data15 to reflect the
"*Lj8C3|n cataract prevalence in the entire Victorian population.
XKz;o^1a^ Univariate analyses with Student’s t-tests and chi-squared
kq) +@p tests were first employed to evaluate risk factors for unoperated
F[>7z3I cataract. Any factors with P < 0.10 were then fitted
xoqiRtlY: into a backwards stepwise logistic regression model. For the
BA~a?"HS Figure 1. Minimum levels of cortical (a), nuclear (b), and posterior subcapsular (c) cataract.
:V&N\>Wo final multivariate models, P < 0.05 was considered statistically
+V)qep" significant. Design effect was assessed through the use
f,Sth7y of cluster-specific models and multivariate models. The
E
S#rs=" design effect was assumed to be additive and an adjustment
Ni+3b made in the variance by adding the variance associated with
5h_<R!jA the design effect prior to constructing the 95% confidence
cvZni#o2) limits.
%xf)m[JU= RESULTS
Yta1` Study population
u~" siH A total of 3271 (83%) of the Melbourne residents, 403
`d75@0: (90%) Melbourne nursing home residents, and 1473 (92%)
uz ]E_&2 rural residents participated. In general, non-participants did
R;H?gE^m- not differ from participants.16 The study population was
;*y|8od
B representative of the Victorian population and Australia as
w+q?T a whole.
g(mxhD!k The Melbourne residents ranged in age from 40 to
;(K 98 years (mean = 59) and 1511 (46%) were male. The
u K'<xM"%T Melbourne nursing home residents ranged in age from 46 to
sT)6nV 101 years (mean = 82) and 85 (21%) were men. The rural
N*~_\x residents ranged in age from 40 to 103 years (mean = 60)
/@Ez" ?V2 and 701 (47.5%) were men.
vKU`C?,L Prevalence of cataract and prior cataract surgery
p?
;-!TUv As would be expected, the rate of any cataract increases
-<_7\09 dramatically with age (Table 1). The weighted rate of any
I[ai: cataract in Victoria was 21.5% (95% CL 18.1, 24.9).
1xz\=HO
T Although the rates varied somewhat between the three
x;Gz6| strata, they were not significantly different as the 95% confidence
CoJ55TAW limits overlapped. The per cent of cataractous eyes
cFLd)mt/ with best-corrected visual acuity of less than 6/12 was 12.5%
\yM-O- { (65/520) for cortical cataract, 18% for nuclear cataract
R8tF/dx>7 (97/534) and 14.4% (27/187) for PSC cataract. Cataract
5^>n5u/ surgery also rose dramatically with age. The overall
|=\91fP68` weighted rate of prior cataract surgery in Victoria was
T j`y J!0 3.79% (95% CL 2.97, 4.60) (Table 2).
N=#4L$@- Risk factors for unoperated cataract
z!:'V] Cases of cataract that had not been removed were classified
co/7l sW
as unoperated cataract. Risk factor analyses for unoperated
h4Ia>^@ cataract were not performed with the nursing home residents
h'l^g%; as information about risk factor exposure was not
{7X#4o0 available for this cohort. The following factors were assessed
/&h+t^l_Qj in relation to unoperated cataract: age, sex, residence
#XI"@pD (urban/rural), language spoken at home (a measure of ethnic
!qA8Zky_ integration), country of birth, parents’ country of birth (a
&3Tx@XhO measure of ethnicity), years since migration, education, use
6
mO" of ophthalmic services, use of optometric services, private
VFO\4:. health insurance status, duration of distance glasses use,
TFy7HX\Oq glaucoma, age-related maculopathy and employment status.
Zn&k[?;Al In this cross sectional study it was not possible to assess the
jJ~Y]dQi
level of visual acuity that would predict a patient’s having
r~8;kcu7 cataract surgery, as visual acuity data prior to cataract
se!mb _! surgery were not available.
HR60 The significant risk factors for unoperated cataract in univariate
t\r:E2
O analyses were related to: whether a participant had
qzK("d ever seen an optometrist, seen an ophthalmologist or been
kX[fy7rVt diagnosed with glaucoma; and participants’ employment
e7xj_QH status (currently employed) and age. These significant
WJ+>e+ factors were placed in a backwards stepwise logistic regression
&[@\ f^~ model. The factors that remained significantly related
%y"J8;U to unoperated cataract were whether participants had ever
"+|L_iuNQ seen an ophthalmologist, seen an optometrist and been
by86zX diagnosed with glaucoma. None of the demographic factors
H9`
f0(H were associated with unoperated cataract in the multivariate
~ y;y(4< model.
J!h^egP The per cent of participants with unoperated cataract
u@=?#a$$ who said that they were dissatisfied or very dissatisfied with
^bUxLa[. Operated and unoperated cataract in Australia 79
6;oe=Q:Q Table 1. Prevalence of any cataracta (excluding previous cataract surgery) by age, gender and cohort
:gI.l1 Age group Sex Urban Rural Nursing home Weighted total
{8@\Ij (years) (%) (%) (%)
_3>djF_
u 40–49 Male 2.56 4.04 0.00 3.00 (1.91, 4.08)
q0O&UE)6Y Female 2.61 1.70 0.00 2.36 (1.61, 3.10)
'r+PH*Mr 50–59 Male 7.69 6.94 0.00 7.47 (5.80, 9.15)
4h|dHXYZ Female 6.67 7.56 0.00 6.92 (5.60, 8.24)
R
1ktj 60–69 Male 20.7 25.0 10.0 22.0 (18.1, 26.0)
&~-~5B|3" Female 27.9 35.7 37.5 30.3 (26.0, 34.7)
V 0{tap} 70–79 Male 43.1 58.7 39.1 48.1 (41.2, 55.1)
z`$J_Cj Y Female 58.6 66.2 55.6 61.0 (56.0, 65.9)
;sPzOS9 80–89 Male 74.0 89.3 92.0 79.3 (72.3, 86.3)
A0xC,V~z Female 91.9 97.0 80.2 92.6 (86.4, 98.8)
^Jx$t/t 90 + Male 100.0 100.0 75.0 98.8 (96.2, 100.0)
}
/:\U
p Female 100.0 100.0 93.8 98.6 (97.0, 100.0)
V"RpH, Age-standardized
[-w@.^:]X (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)
l@~LV}BI aCortical > 4/16, nuclear > standard 2, posterior subcapsular > 1 mm2
rdJB*Rlkh their current vision was 30% (290/683), compared with 27%
{G*QY%j^ (26/95) of participants with prior cataract surgery (chisquared,
GAEO$e: 1 d.f. = 0.25, P = 0.62).
TGV Outcomes of cataract surgery
1n%8j*bJq Two hundred and forty-nine eyes had undergone prior
4]XI"-M^D cataract surgery. Of these 249 operated eyes, 49 (20%) were
!3}deY8;# left aphakic, 6 (2.4%) had anterior chamber intraocular
or?%-) lenses and 194 (78%) had posterior chamber intraocular
|3eGz%Sd lenses. The rate of capsulotomy in the eyes with intact
H
s?zq posterior capsules was 36% (73/202). Fifteen per cent of
&%F@O<
: eyes (17/114) with a clear posterior capsule had bestcorrected
O/OiQ^T visual acuity of less than 6/12 compared with 43%
]=&L