ABSTRACT
{zb'Z Yz Purpose: To quantify the prevalence of cataract, the outcomes
aoN\n]g of cataract surgery and the factors related to
LIID(s!bX unoperated cataract in Australia.
~~/,2^ Methods: Participants were recruited from the Visual
^@^8iZ Impairment Project: a cluster, stratified sample of more than
?6:qAF
w 5000 Victorians aged 40 years and over. At examination
60+ zoL' sites interviews, clinical examinations and lens photography
:'p)xw4K| were performed. Cataract was defined in participants who
0/Q_%
: had: had previous cataract surgery, cortical cataract greater
9lYKG^#D than 4/16, nuclear greater than Wilmer standard 2, or
xk,Uf,,> posterior subcapsular greater than 1 mm2.
$Z G&d Results: The participant group comprised 3271 Melbourne
mo|
D residents, 403 Melbourne nursing home residents and 1473
=7Ud-5c rural residents.The weighted rate of any cataract in Victoria
!K-1tp$ was 21.5%. The overall weighted rate of prior cataract
F1yn@a "=J surgery was 3.79%. Two hundred and forty-nine eyes had
p'h'Cz had prior cataract surgery. Of these 249 procedures, 49
CPJ<A,V (20%) were aphakic, 6 (2.4%) had anterior chamber
[K4cxqlfk intraocular lenses and 194 (78%) had posterior chamber
Ub3$ ` intraocular lenses.Two hundred and eleven of these operated
oZ%uq78#[% eyes (85%) had best-corrected visual acuity of 6/12 or
b-&rMML better, the legal requirement for a driver’s license.Twentyseven
[edF'7La (11%) had visual acuity of less than 6/18 (moderate
o-8{C0>: vision impairment). Complications of cataract surgery
~-'2jb*8 caused reduced vision in four of the 27 eyes (15%), or 1.9%
TQn!MUj/^ of operated eyes. Three of these four eyes had undergone
fV"Y/9}( intracapsular cataract extraction and the fourth eye had an
JT
7WZc) opaque posterior capsule. No one had bilateral vision
pf8'xdExH) impairment as a result of cataract surgery. Surprisingly, no
H9T~7e+ particular demographic factors (such as age, gender, rural
;
<FAcR residence, occupation, employment status, health insurance
RE t
&QP status, ethnicity) were related to the presence of unoperated
Vl^x_gs#_] cataract.
N]W*ei Conclusions: Although the overall prevalence of cataract is
&E`Nu (e quite high, no particular subgroup is systematically underserviced
5p.rd0T]l3 in terms of cataract surgery. Overall, the results of
mlByE,S2E cataract surgery are very good, with the majority of eyes
*B&P[n achieving driving vision following cataract extraction.
6m&GN4Ca Key words: cataract extraction, health planning, health
(XOz_K6c%K services accessibility, prevalence
5X0ex. INTRODUCTION
sPK ]:iC Cataract is the leading cause of blindness worldwide and, in
Xq1#rK( Australia, cataract extractions account for the majority of all
j}Tv/O,f ophthalmic procedures.1 Over the period 1985–94, the rate
0Jv6?7]LKa of cataract surgery in Australia was twice as high as would be
Sj ovL@X expected from the growth in the elderly population.1
:3M,]W] Although there have been a number of studies reporting
e, sS. the prevalence of cataract in various populations,2–6 there is
Apu-9|oP little information about determinants of cataract surgery in
6@|!m ' the population. A previous survey of Australian ophthalmologists
l
i<9nMZ< showed that patient concern and lifestyle, rather
xiW}P% bf than visual acuity itself, are the primary factors for referral
[
&Wy $ for cataract surgery.7 This supports prior research which has
C 9%bD shown that visual acuity is not a strong predictor of need for
lz=DGm
cataract surgery.8,9 Elsewhere, socioeconomic status has
ta&z lZt been shown to be related to cataract surgery rates.10
(U5XB
[r_P To appropriately plan health care services, information is
ywm"{ U?8 needed about the prevalence of age-related cataract in the
-F`gRAr- community as well as the factors associated with cataract
og$dv
23 surgery. The purpose of this study is to quantify the prevalence
-}@
C9Ja[? of any cataract in Australia, to describe the factors
kYS#P(1 related to unoperated cataract in the community and to
gB#!g@ describe the visual outcomes of cataract surgery.
tLJ 7tnB METHODS
#NT~GhWFf Study population
a3A-N] ;f Details about the study methodology for the Visual
AYNz {9 Impairment Project have been published previously.11
OY"BaSEOw} Briefly, cluster sampling within three strata was employed to
6+sz4 recruit subjects aged 40 years and over to participate.
>o"s1*
{ Within the Melbourne Statistical Division, nine pairs of
LZ#A`&qUd census collector districts were randomly selected. Fourteen
Z+R-}< nursing homes within a 5 km radius of these nine test sites
bIt{kzuQC were randomly chosen to recruit nursing home residents.
rDaiAx& Clinical and Experimental Ophthalmology (2000) 28, 77–82
v'L"sgW6I Original Article
(|W6p%( Operated and unoperated cataract in Australia
!OV+2suu1 Catherine A McCarty PhD, MPH, Mukesh B Nanjan PhD, Hugh R Taylor MD
=]Y'xzJuu Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
"`K73M,c?9 n Correspondence: Dr Cathy McCarty MPH, Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, 32 Gisborne Street, East Melbourne,
6mZpyt Victoria 3002, Australia. Email:
cathy@cera.unimelb.edu.au I<lkociUCG 78 McCarty et al.
yaj1nq!*" Finally, four pairs of census collector districts in four rural
i/N6 8 Victorian communities were randomly selected to recruit rural
c1%ki%J# residents. A household census was conducted to identify
G* mLb1 eligible residents aged 40 years and over who had been a
K<l
dl. resident at that address for at least 6 months. At the time of
aj+I+r"~ the household census, basic information about age, sex,
M>Ws}Y country of birth, language spoken at home, education, use of
h" YA>_1 corrective spectacles and use of eye care services was collected.
Re\V<\$J Eligible residents were then invited to attend a local
~xZ)btf examination site for a more detailed interview and examination.
Qa16x<Xlm The study protocol was approved by the Royal Victorian
5geZ6]| Eye and Ear Hospital Human Research Ethics Committee.
\4q1<j Assessment of cataract
]kkH|b$[T A standardized ophthalmic examination was performed after
( (mNB]sy pupil dilatation with one drop of 10% phenylephrine
M\9p-%"L hydrochloride. Lens opacities were graded clinically at the
EJrQ9"x&n time of the examination and subsequently from photos using
zQ eXN7$ the Wilmer cataract photo-grading system.12 Cortical and
gJn_8\,C>Q posterior subcapsular (PSC) opacities were assessed on
x: Tm4V{ retroillumination and measured as the proportion (in 1/16)
_1Iw"K49Qx of pupil circumference occupied by opacity. For this analysis,
0SLn0vD! cortical cataract was defined as 4/16 or greater opacity,
`Axn
PSC cataract was defined as opacity equal to or greater than
;fDs9=3# 1 mm2 and nuclear cataract was defined as opacity equal to
D(S^g+rd or greater than Wilmer standard 2,12 independent of visual
~|)'vK8W acuity. Examples of the minimum opacities defined as cortical,
"^iw {]~U nuclear and PSC cataract are presented in Figure 1.
;i&'va$ Bilateral congenital cataracts or cataracts secondary to
VJ(#FA2 intraocular inflammation or trauma were excluded from the
#PRkqg+| analysis. Two cases of bilateral secondary cataract and eight
'.DFyHsq cases of bilateral congenital cataract were excluded from the
PM%Gsy]q analyses.
Yf(QU`w_ A Topcon® SL5 photo slit-lamp (Topcon America Corp.,
vvG#O[| O Paramus, NJ, USA) with a 0.1 mm slit beam of 9.0 mm in
y|%rW height set to an incident angle of 30° was used for examinations.
o;@T6-VH Ektachrome® 200 ASA colour slide film (Eastman
4h~o>(Sq Kodak Company, Rochester, NY, USA) was used to photograph
5 eWGX the nuclear opacities. The cortical opacities were
E|d 8vt photographed with an Oxford® retroillumination camera
3v%V\kO=F (Marcher Enterprises Ltd, Hereford, UK) and T-MAX® 400
<Cw)S8t film (Eastman Kodak). Photographs were graded separately
(-(sBQ a+ by two research assistants and discrepancies were adjudicated
"V;M,/Q| by an independent reviewer. Any discrepancies
+
>oA@z between the clinical grades and the photograph grades were
J_A5,K*r| resolved. Except in cases where photographs were missing,
auTApYS53 the photograph grades were used in the analyses. Photograph
IPoNAi<b grades were available for 4301 (84%) for cortical
Q0_UBm^f cataract, 4147 (81%) for nuclear cataract and 4303 (84%)
IOsitMOX: for PSC cataract. Cataract status was classified according to
Ln})\
UDK) the severity of the opacity in the worse eye.
w#5^A(NR Assessment of risk factors
y#Ao6Od6 A standardized questionnaire was used to obtain information
d[5?P?h') about education, employment and ethnic background.11
)FkJ=P0 Specific information was elicited on the occurrence, duration
V\"x#uB and treatment of a number of medical conditions,
Z`23z(+ including ocular trauma, arthritis, diabetes, gout, hypertension
DUxj^,mf, and mental illness. Information about the use, dose and
G:QaWqUb duration of tobacco, alcohol, analgesics and steriods were
2#:h.8 collected, and a food frequency questionnaire was used to
`2y2Bk determine current consumption of dietary sources of antioxidants
~
FW@ and use of vitamin supplements.
sHSZIkB-r Data management and statistical analysis
~1Q$Fg
Lk Data were collected either by direct computer entry with a
|>(;gr/5( questionnaire programmed in Paradox© (Carel Corporation,
z )
2h\S Ottawa, Canada) with internal consistency checks, or
h
+Dp<b on self-coding forms. Open-ended responses were coded at
y1!c:& a later time. Data that were entered on the self-coded forms
lz?F ,]. were entered into a computer with double data entry and
&
Me%ZM0 reconciliation of any inconsistencies. Data range and consistency
e.%`
tK3J checks were performed on the entire data set.
mYf7?I~ SAS© version 6.1 (SAS Institute, Cary, North Carolina) was
cTpAU9|( employed for statistical analyses.
"MD Ninety-five per cent confidence limits around the agespecific
C3^QNhv rates were calculated according to Cochran13 to
y,i:BQJ< account for the effect of the cluster sampling. Ninety-five
;H5PiSq;z per cent confidence limits around age-standardized rates
\-Mzs 0R were calculated according to Breslow and Day.14 The strataspecific
K'EGm #I data were weighted according to the 1996
Z> jk\[ Australian Bureau of Statistics census data15 to reflect the
7RQ.oe
e cataract prevalence in the entire Victorian population.
pZx'%-\-T Univariate analyses with Student’s t-tests and chi-squared
{k=H5<FV tests were first employed to evaluate risk factors for unoperated
01VEz
8[\ cataract. Any factors with P < 0.10 were then fitted
#E%0 o into a backwards stepwise logistic regression model. For the
h0ufl.N_% Figure 1. Minimum levels of cortical (a), nuclear (b), and posterior subcapsular (c) cataract.
m0+X 109 final multivariate models, P < 0.05 was considered statistically
| X/QSL significant. Design effect was assessed through the use
j^
VAA\ of cluster-specific models and multivariate models. The
kZXsL design effect was assumed to be additive and an adjustment
y%A!|aBu made in the variance by adding the variance associated with
L P?E the design effect prior to constructing the 95% confidence
J0@<6~V6o limits.
*5'U3py RESULTS
,2\?kPoc8 Study population
x9Veg4Z7 A total of 3271 (83%) of the Melbourne residents, 403
42X N*br (90%) Melbourne nursing home residents, and 1473 (92%)
+cS%b}O`$ rural residents participated. In general, non-participants did
[J4
Aig
not differ from participants.16 The study population was
\*{tAF representative of the Victorian population and Australia as
o4I&?d7
;" a whole.
^MJT lRUb The Melbourne residents ranged in age from 40 to
qI-q%]l 98 years (mean = 59) and 1511 (46%) were male. The
3QlV,)} Melbourne nursing home residents ranged in age from 46 to
x2gnB@t 101 years (mean = 82) and 85 (21%) were men. The rural
-:92<G\D residents ranged in age from 40 to 103 years (mean = 60)
.yp"6S^b and 701 (47.5%) were men.
L`E^B
uP/ Prevalence of cataract and prior cataract surgery
A#&Q(g\YE As would be expected, the rate of any cataract increases
Y@WCp dramatically with age (Table 1). The weighted rate of any
a o_A%?Ld cataract in Victoria was 21.5% (95% CL 18.1, 24.9).
q^nSYp# Although the rates varied somewhat between the three
m
Iu- strata, they were not significantly different as the 95% confidence
-P!_<\q\l limits overlapped. The per cent of cataractous eyes
BPAz.K Q with best-corrected visual acuity of less than 6/12 was 12.5%
iO^z7Y7 (65/520) for cortical cataract, 18% for nuclear cataract
0fc]RkHs" (97/534) and 14.4% (27/187) for PSC cataract. Cataract
}T
!2IaAB surgery also rose dramatically with age. The overall
nsChNwPX weighted rate of prior cataract surgery in Victoria was
b?&=gm%oU 3.79% (95% CL 2.97, 4.60) (Table 2).
C^Jf&a Risk factors for unoperated cataract
(GnwK1f Cases of cataract that had not been removed were classified
Wj N0KA as unoperated cataract. Risk factor analyses for unoperated
v] *(Wd~| cataract were not performed with the nursing home residents
J:M)gh~# as information about risk factor exposure was not
Bsm>^zZ`YU available for this cohort. The following factors were assessed
UloZo?
e` in relation to unoperated cataract: age, sex, residence
oYWcX9R (urban/rural), language spoken at home (a measure of ethnic
%\=oy=f integration), country of birth, parents’ country of birth (a
9T*%CI measure of ethnicity), years since migration, education, use
.*H0{ of ophthalmic services, use of optometric services, private
xJ"CAg|B health insurance status, duration of distance glasses use,
,z}wR::% glaucoma, age-related maculopathy and employment status.
X8T7(w<0%f In this cross sectional study it was not possible to assess the
W68d"J%>_ level of visual acuity that would predict a patient’s having
5- Q`v/w; cataract surgery, as visual acuity data prior to cataract
nU"V@_?\ surgery were not available.
=l`xXma The significant risk factors for unoperated cataract in univariate
Yuy7TeJRx analyses were related to: whether a participant had
g%w@v$ ever seen an optometrist, seen an ophthalmologist or been
md[FtcY\ diagnosed with glaucoma; and participants’ employment
^&t(O1.- status (currently employed) and age. These significant
Z-m,~Hh factors were placed in a backwards stepwise logistic regression
ZyqTtA!A model. The factors that remained significantly related
t;+6>sTu to unoperated cataract were whether participants had ever
Fz+0 h" seen an ophthalmologist, seen an optometrist and been
nLq7J: diagnosed with glaucoma. None of the demographic factors
H[ %Fo were associated with unoperated cataract in the multivariate
1Oo^ model.
+j 5u[X The per cent of participants with unoperated cataract
zx\N^R;Jq who said that they were dissatisfied or very dissatisfied with
v>Il# Operated and unoperated cataract in Australia 79
>Uvtsj# Table 1. Prevalence of any cataracta (excluding previous cataract surgery) by age, gender and cohort
%+$P<Rw7 Age group Sex Urban Rural Nursing home Weighted total
r
@~T}<I (years) (%) (%) (%)
&sL5Pt_ 40–49 Male 2.56 4.04 0.00 3.00 (1.91, 4.08)
x&R&\}@G m Female 2.61 1.70 0.00 2.36 (1.61, 3.10)
A"Rzn1/ 50–59 Male 7.69 6.94 0.00 7.47 (5.80, 9.15)
@M4~,O6- Female 6.67 7.56 0.00 6.92 (5.60, 8.24)
8QYG"CA6/ 60–69 Male 20.7 25.0 10.0 22.0 (18.1, 26.0)
w_^&X;0^ Female 27.9 35.7 37.5 30.3 (26.0, 34.7)
c>
K/f7 70–79 Male 43.1 58.7 39.1 48.1 (41.2, 55.1)
MAR
kTxzi Female 58.6 66.2 55.6 61.0 (56.0, 65.9)
t; n6Q0 80–89 Male 74.0 89.3 92.0 79.3 (72.3, 86.3)
14\%2nE Female 91.9 97.0 80.2 92.6 (86.4, 98.8)
S$]:3 90 + Male 100.0 100.0 75.0 98.8 (96.2, 100.0)
tH:ea$A
Female 100.0 100.0 93.8 98.6 (97.0, 100.0)
?9X#{p>q Age-standardized
S^)r,cC (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)
Hi|2z5=V aCortical > 4/16, nuclear > standard 2, posterior subcapsular > 1 mm2
L5yxaF{] their current vision was 30% (290/683), compared with 27%
~<