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Background: To investigate the distribution of refractive errors and their characteristics in older adults from a Polish population. Methods: The study design was a cross-sectional study. A total of 1107 men and women were interviewed and underwent detailed ophthalmic examinations, 998 subjects underwent refraction. Myopia was defined as spherical equivalent (SER) refraction ≤−0.5 dioptres (D) and hyperopia was defined as SER ≥+0.5 dioptres (D). Results: Among those who were refracted the distribution of myopia and hyperopia was 24.1% (95% CI 21.4–26.7) and 37.5% (95% CI 34.5–40.5), respectively. Myopia decreased from 28.7% in subjects aged 35–59 years to 19.3% in those aged 60 years or older and hyperopia increased from 21.8% at 35–59 years of age to 53.3% in subjects aged ≥60 years. Multiple regression analysis showed decreasing age (OR 0.98, 95% CI 0.96–1.00), female gender (OR 1.87, 95% CI 1.18–2.95) and presence of cataract (OR 2.40, 95% CI 1.24–4.63) were independent risk factors associated with myopia. Conclusions: The distribution of refractive errors found in our study is similar to those reported in other Caucasian populations and differs from Asian populations. Myopia was positively associated with younger age, female gender and presence of cataract.
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International Journal of
Environmental Research
and Public Health
Article
Characteristics of Refractive Errors in a Population of
Adults in the Central Region of Poland
Michal S. Nowak 1, *ID , Piotr Jurowski 2, Andrzej Grzybowski 3and Janusz Smigielski 4
1Provisus Eye Clinic, 112 Redzinska str., 42-209 Czestochowa, Poland
2
Department of Ophthalmology and Visual Rehabilitation, Medical University of Lodz, 113 Zeromskiego str.,
90-549 Lodz, Poland; p.jurowski@vp.pl
3Department of Ophthalmology, University of Warmia and Mazury, 30 Warszawska str., 10-082 Olsztyn,
Poland; ae.grzybowski@gmail.com
4
Department of Statistics, State University of Applied Science in Konin, 1 Przyjazni str., 65-510 Konin, Poland;
janusz.smigielski.stat@gmail.com
*Correspondence: michaelnovak@interia.pl; Tel.: +48-888-801-010-x
Received: 18 November 2017; Accepted: 6 January 2018; Published: 8 January 2018
Abstract:
Background: To investigate the distribution of refractive errors and their characteristics in
older adults from a Polish population. Methods: The study design was a cross-sectional study. A total
of 1107 men and women were interviewed and underwent detailed ophthalmic examinations, 998
subjects underwent refraction. Myopia was defined as spherical equivalent (SER) refraction
≤−
0.5
dioptres (D) and hyperopia was defined as SER
+0.5 dioptres (D). Results: Among those who were
refracted the distribution of myopia and hyperopia was 24.1% (95% CI 21.4–26.7) and 37.5% (95% CI
34.5–40.5), respectively. Myopia decreased from 28.7% in subjects aged 35–59 years to 19.3% in those
aged 60 years or older and hyperopia increased from 21.8% at 35–59 years of age to 53.3% in subjects
aged
60 years. Multiple regression analysis showed decreasing age (OR 0.98, 95% CI 0.96–1.00),
female gender (OR 1.87, 95% CI 1.18–2.95) and presence of cataract (OR 2.40, 95% CI 1.24–4.63) were
independent risk factors associated with myopia. Conclusions: The distribution of refractive errors
found in our study is similar to those reported in other Caucasian populations and differs from
Asian populations. Myopia was positively associated with younger age, female gender and presence
of cataract.
Keywords: myopia; hyperopia; anisometropia
1. Introduction
According to the latest reports of World Health Organization (WHO) uncorrected refractive
errors are the most common cause of visual impairment worldwide, accounting for 43% of cases
and representing an important cause of blindness [
1
]. Uncorrected refractive errors have also been
associated with reduced vision-related quality of life and with loss of independence [
2
,
3
]. The estimated
global cost of lost productivity due to refractive error vision impairment in 2007 was more than
200 billion United States dollars [
4
]. Most of this could be eliminated simply with refraction and
appropriate vision correction [5,6].
The prevalence of refractive errors has been reported to vary with race, age, gender and geographic
regions. Population-based data indicate the prevalence of myopia as being higher in children of Chinese
ethnicity; but in Chinese adults the rate of myopia is not much higher than what is found in White
adult population [
2
]. Environmental factors like level of education, occupation, near-work load, time
outdoors as a child are also associated with aetiology of refractive errors [
2
,
7
9
]. The gender differences
in the prevalence of refractive errors have been also reported, but many studies have failed to confirm
these associations [7,1014].
Int. J. Environ. Res. Public Health 2018,15, 90; doi:10.3390/ijerph15010090 www.mdpi.com/journal/ijerph
Int. J. Environ. Res. Public Health 2018,15, 90 2 of 10
During the last two decades several studies concerning the prevalence of refractive errors in
Asia [
12
19
], Australia [
20
,
21
] and North America [
2
,
9
,
22
24
] have been undertaken. However there
are very few from Europe and all are from the Western part [
7
,
11
,
25
,
26
]. Poland is the biggest eastern
European country, with a population of 38 million people according to the 2011 national census [
27
].
Due to a lack of data from Poland and other post-Soviet nations, we conducted an epidemiological
survey on a sample population of older adults in the city of Lodz, which results have recently been
published [
6
,
28
]. The aim of the present study was to investigate the distribution of refractive errors
and their characteristics in this population.
2. Materials and Methods
2.1. Subjects, Eye Examinations and Definitions
The study design was a cross-sectional study. The sampling and recruitment methods for this
study have been described in details in our previous papers [
6
,
28
]. Sample size for the study was
calculated with 99% confidence, within an error bound of 5%. The sample size requirement was 661,
as calculated by:
N=Z2/4d2(1)
where Z = 2.57 for 99% confidence interval and d = 0.05 for 5% error bound. After allowing for
an arbitrary 50% increase in sample size to accommodate possible inefficiencies associated with the
sample design, the sample size requirement increased to 991 subjects [
6
,
28
]. We decided to define an
older adult as person aged
35 years because in our previous reports conducted on young males in
the military population, we considered young adults as persons aged 18–34 years [
29
,
30
]. We used
simple systematic sampling to select our study population. In total 14,110 outpatients were examined
in the Department of Ophthalmology and Visual Rehabilitation of the Medical University of Lodz in
year 2012 and we included into the study every tenth subject aged 35 years and older [
28
]. Based on
age, the study subjects were divided into two groups; group I, aged 35–59 years, and group II, aged
60 years and older. All participants were interviewed and information regarding brief details of the eye
conditions, age, sex and socioeconomic status was collected. Comprehensive ophthalmic examination
included: distance visual acuity (VA) testing, a cover test, binocular and color vision assessments,
intraocular pressure (IOP) measurements as well as slit lamp and indirect ophthalmoscopic evaluation
of the anterior and posterior segments and other examinations where needed. Distance visual acuity
(VA) was tested monocularly, using a retroilluminated Snellen chart placed at 4 m. Because the present
study was a continuation of our previous reports as mentioned earlier, we used the methodology of
refraction measurements and definitions of refractive errors from the Polish Army national regulations
for ophthalmic examination [
29
,
30
]. Autorefraction data were obtained in all study subjects using
a Topcon KR 8900 autorefractometer (supplied by Topcon Corporation, Tokyo, Japan). Cycloplegic
refraction data were obtained only in eyes presenting with distance visual acuity <20/40 Snellen
(0.3 logMAR). Based on this, subjective refraction tests using only spherical or cylindrical glasses were
performed to achieve best corrected visual acuity (BCVA). Spherical equivalent (SER) refractive error,
defined as sphere plus half cylinder, was applied for myopia and hyperopia calculations. According
to the Polish Army regulations myopia was defined as spherical equivalent (SER) refraction
≤−
0.5
dioptres (D), hyperopia was defined as SER
+0.5 dioptres (D) and emmetropia as SER between
0.5 and +0.5 diopters (D). Astigmatism was considered if the cylinder was
0.5 dioptres [
29
,
30
].
Anisometropia was defined as difference of SER greater than 1.0 dioptres (D) between the right and
the left eyes. The distribution of refractive errors was presented binocularly. If the study subject
had one myopic and a fellow hyperopic eye, the refractive error of the eye with larger spherical
equivalent was taken into account. Eyes with previous history of cataract surgery, which underwent
corneal transplantation and with ocular conditions which precluded autorefraction measurements
were excluded from statistical analysis.
Int. J. Environ. Res. Public Health 2018,15, 90 3 of 10
For this report the presence of cataract, aphakia or pseudophakia was determined on the slit lamp
examination. Glaucoma was diagnosed when characteristic morphological changes of the optic nerve
head and retinal nerve fiber layer (RNFL) not related to other ocular disease or congenital anomalies
were present, associated with typical glaucomatous visual filed loss. The ocular hypertension
(OHT) was diagnosed if the intraocular pressure was elevated with all other ocular findings within
normal limits [
28
,
31
]. In a few subjects with large media opacities, when results of optic nerve head
examinations and visual field were unavailable, glaucoma was diagnosed basing on previous evidence
of glaucoma treatment.
Because of the nature of the survey, verbal informed consent was obtained from all study
participants. The institutional review board waived the need for written informed consent from
the participants, but otherwise the work was conducted in accordance with the provisions of the
Declaration of Helsinki for research involving human subjects and was approved by the ethic
committee of the Medical University of Lodz (Ethical Approval Code RNN/848/12/KB).
2.2. Data Management and Statistical Analysis
A commercially available software STATISTICA v. 10.1 PL (StatSoft Polska, Krakow, Poland)
was used to perform all statistical analyses. Age-specific prevalence rates of myopia, hyperopia and
astigmatism were calculated in subjects with distance visual acuity <20/40 after cycloplegic refraction.
The associations between the distance visual acuity categories as well as refractive errors with the
subjects’ age and gender were explored by
χ2
statistics (p< 0.05). Multiple logistic regression statistics
were used to investigate the association of myopia and hyperopia with age, gender, socioeconomic
status of participants as well as with cataract, glaucoma and ocular hypertension (OHT). All presented
confidence intervals (CIs) were 95% CI and odds ratios (ORs) were computed.
3. Results
3.1. Subjects
A total of 1107 white subjects aged
35 years, most of whom live or have lived in the city of
Lodz, in central Poland were enumerated and included into the study. The mean age of the study
subjects was 60.4
±
12.8 years (range, 35–97 years). There were 465 men (42%) and 642 women (58%).
According to 2011 national census, our study participants were a fair representation of the population
of the city of Lodz in terms of sex distribution (statistical analysis- chi square test:
χ2
= 3.64, p> 0.05)
and socioeconomic status [
27
]. Statistical analysis also revealed that our two age groups did not vary
significantly in gender (
χ2
test p= 0.158). Socio-demographic analysis revealed only 31 subjects (2.8%)
declared to have no source of income. The number of subjects with no income was significantly higher
in age group 35–59 years.
3.2. Distribution of Distance Visual Acuity and Refractive Errors
Visual acuity (VA) measurements were obtained in 2214 eyes of 1107 subjects (Table 1). In total
72.5% (95% CI 69.9–75.1) subjects had normal or near normal vision-distance VA of
20/40 in both eyes
and 27.5% (95% CI 24.8–30.1) had distance VA of <20/40 in worse-seeing eye. There were significant
differences in distant visual acuity between the age and gender categories (p= 0.01). The number of
individuals with better VA was lower, and the number of individuals with worse VA was higher in the
age group
60 years and in women. After cycloplegic and subjective refractions only 1.8% (95% CI
1.0–2.6) of subjects had best corrected visual acuity (BCVA) of 20/200 in both eyes.
Data on refractive errors were available for 998 individuals (Table 2). Myopia was found in 21.7%
of the males and in 25.7% of the women. The distribution of hyperopia and astigmatism was 37.5%
and 10.8%, respectively. Gender-specific rates of myopia, hyperopia and astigmatism were statistically
significant (
χ2
test p< 0.001). Hyperopia was more common in women (42.0%) and asigmatism in men
(13.0%) than in women (9.3%). In age group 60 years and older there was a significant increase in the
Int. J. Environ. Res. Public Health 2018,15, 90 4 of 10
number of subjects with hyperopia and astigmatism compared to age group 35–59 years; while the
number of subjects with myopia decreased with age. The mean spherical equivalent refraction (SER)
of myopia and hyperopia was 3.1
±
2.4 diopters and 2.0
±
1.3 diopters, respectively. The characteristic
of myopic and hyperopic refractive errors obtained with autorefraction is presented on Figures 1and 2.
Anisometropia greater than 1.0 dioptres (D) was found in 9.2% (95% CI 5.5–12.9) of subjects.
Table 1. Distribution of distance visual acuity among our study subjects.
Visual Acuity Category Right Eyes n(%; 95% CI) Left Eyes n(%; 95% CI) Both Eyes n(%; 95% CI)
20/40 842 (76.0%; 73.5.5–78.6) 846 (76.4%; 73.9–78.9) 803 (72.5%; 69.9–75.1)
>20/200 <20/40 209 (18.9%; 16.6–21.2) 202 (18.3%; 16.0–20.5) 224 (20.2%; 17.8–22.6) †
20/200 56 (5.1%; 3.8–6.3) 59 (5.3%; 4.0–6.6) 80 (7.3%; 5.7–8.7) †
All 1107 (100%) 1107 (100%) 1107 (100%)
35–59 Years 60 Years
20/40 397 (76.4%; 72.7–80.0) 406 (69.2%; 65.4–72.9)
>20/200 <20/40 88 (16.9%; 13.7–20.1) † 136 (23.2%; 19.7–26.6) †
20/200 35 (6.7%; 4.6–8.9) † 45 (7.6%; 5.5–9.8) †
all 520 (100%) 587 (100%)
χ2test p< 0.001
Men Women
20/40 358 (77.0%; 73.2–80.8) 445 (69.3%; 65.7–72.9)
>20/200 <20/40 76 (16.3%; 13.0–19.7) † 148 (23.1%; 19.8–26.3) †
20/200 31 (6.7%; 4.4–8.9) † 49 (7.6%; 5.6–9.7) †
all 465 (100%) 642 (100%)
χ2test, p= 0.01
† in worst eye.
Table 2. Distribution of refractive errors in a researched group.
Refractive Error 35–59 Years (n;
%; 95% CI)
60 Years (n; %;
95% CI)
Men (n; %;
95% CI)
Women (n; %:
95% CI)
Totally (n; %;
95% CI)
Emmetropia (>0.5 D,
<+0.5 D, SE)
214 (42.7%;
38.4–47.0)
62 (12.5%;
9.6–15.4)
142 (34.2%;
29.6–38.8)
134 (23.0%;
19.6–26.4)
276 (27.6%;
24.9–30.4)
Myopia (≤−0.5 D, SE) 144 (28.7%;
24.8–32.7)
96 (19.3%;
15.8–22.8)
90 (21.7%;
17.7–25.6)
150 (25.7%;
22.2–29.3)
240 (24.1%;
21.4–26.7) †
Hyperopia (+0.5 D, SE) 109 (21.8%;
18.1–25.4)
265 (53.3%;
48.9–57.7)
129 (31.1%;
26.6–35.5)
245 (42.0%;
38.0–46.0)
374 (37.5%;
34.5–40.5) †
Astigmatism (0.5 D, Cyl) 34 (6.8%;
4.6–9.0)
74 (14.9%;
11.8–18.0)
54 (13.0%;
9.8–16.2)
54 (9.3%;
6.9–11.6)
108 (10.8%;
8.9–12.7) †
All 501 (100%) 497 (100%) 415 (100%) 583 (100%) 998 (100%)
χ2test p< 0.001; † at least in one eye.
Int.J.Environ.Res.PublicHealth2018,15,90 4of10
sphericalequivalentrefraction(SER)ofmyopiaandhyperopiawas3.1±2.4dioptersand2.0±1.3
diopters,respectively.Thecharacteristicofmyopicandhyperopicrefractiveerrorsobtainedwith
autorefractionispresentedonFigures1and2.Anisometropiagreaterthan1.0dioptres(D)was
foundin9.2%(95%CI5.5–12.9)ofsubjects.
Table1.Distributionofdistancevisualacuityamongourstudysubjects.
VisualAcuityCategoryRightEyesn(%;95%CI) leftEyesn(%;95%CI) BothEyesn(%;95%CI)
20/40842(76.0%;73.5.5–78.6)846(76.4%;73.9–78.9)803(72.5%;69.9–75.1)
>20/200<20/40209(18.9%;16.6–21.2)202(18.3%;16.0–20.5)224(20.2%;17.8–22.6)
20/20056(5.1%;3.8–6.3)59(5.3%;4.0–6.6)80(7.3%;5.7–8.7)
All1107(100%)1107(100%)1107(100%)
35
59Years 60Years
20/40397(76.4%;72.7–80.0)406(69.2%;65.4–72.9)
>20/200<20/4088(16.9%;13.7–20.1)136(23.2%;19.7–26.6)
20/20035(6.7%;4.6–8.9)45(7.6%;5.5–9.8)
all520(100%)587(100%)
χ2testp<0.001
Men Women
20/40358(77.0%;73.2–80.8)445(69.3%;65.7–72.9)
>20/200<20/4076(16.3%;13.0–19.7)148(23.1%;19.8–26.3)
20/20031(6.7%;4.4–8.9)49(7.6%;5.6–9.7)
all465(100%)642(100%)
χ2test,p=0.01
inworsteye.
Table2.Distributionofrefractiveerrorsinaresearchedgroup.
RefractiveError35–59Years(n;%;
95%CI)
60Years(n;%;
95%CI)
Men(n;%;
95%CI)
Women(n;%:
95%CI)
Totally(n;
%;95%CI)
Emmetropia(>0.5D,<+0.5D,SE)214(42.7%;
38.4–47.0)
62(12.5%;
9.6–15.4)
142(34.2%;
29.6–38.8)
134(23.0%;
19.6–26.4)
276(27.6%;
24.9–30.4)
Myopia(≤−0.5D,SE) 144(28.7%;
24.8–32.7)
96(19.3%;
15.8–22.8)
90(21.7%;
17.7–25.6)
150(25.7%;
22.2–29.3)
240(24.1%;
21.4–26.7)
Hyperopia(+0.5D,SE)109(21.8%;
18.1–25.4)
265(53.3%;
48.9–57.7)
129(31.1%;
26.6–35.5)
245(42.0%;
38.0–46.0)
374(37.5%;
34.5–40.5)
Astigmatism(0.5D,Cyl)34(6.8%;
4.6–9.0)
74(14.9%;
11.8–18.0)
54(13.0%;
9.8–16.2)
54(9.3%;
6.9–11.6)
108(10.8%;
8.9–12.7)
All501(100%)497(100%)415(100%)583(100%)998(100%)
χ2testp<0.001;atleastinoneeye.
Figure1.Histogramofmyopicrefractiveerrorintheresearchedpopulation.
Figure 1. Histogram of myopic refractive error in the researched population.
Int. J. Environ. Res. Public Health 2018,15, 90 5 of 10
Int. J. Environ. Res. Public Health 2018, 15, 90 5 of 10
Figure 2. Histogram of hyperopic refractive error in the researched population.
3.3. Multiple Logistic Regression Modeling
Multivariate logistic regression models were constructed to analyze the risk factors for myopia
and hyperopia in this group (Table 3).
Table 3. Multiple logistic regression models of the risk factors for myopia and hyperopia.
Variables Myopia 0.5 D Hyperopia 0.5 D
OR, 95% CI, pValue OR, 95% CI, p Value
Age, per year increase 0.98 (0.96
1.00); p = 0.023 1.02 (1.001.04); p = 0.046
Women vs. men 1.87 (1.18
2.95); p = 0.007 2.16 (1.383.38); p = 0.001
Any cataract 2.40 (1.24
4.63); p = 0.009 1.68 (0.962.96); p = 0.070
Glaucoma and ocular hypertension (OHT) 0.36 (0.11
1.19); p = 0.094 0.52 (0.221.23); p = 0.136
Socioeconomic status 1.21 (0.35
4.14); p = 0.766 1.87 (0.625.63); p = 0.264
Our analysis showed that hyperopia was significantly associated with age (OR 1.02, 95% CI
1.001.04). Myopia was also significantly associated with age (OR 0.98, 95% CI 0.961.00) but in
opposite direction. After adjusting for all other factors women were more likely to have hyperopia
(OR 2.16, 95% CI 1.383.38) compared with myopia (OR 1.87, 95% CI 1.182.95). The presence of
cataract was a significant risk factor for myopia (OR 2.40, 95% CI 1.244.63). No association was
found between refractive errors and socioeconomic status of our study subjects.
4. Discussion
This study describes refractive errors in a group of Polish citizens’ aged 35 years or older, living
in the city of Lodz in central Poland. It provides for the first time data concerning the distribution of
refractive errors and their characteristics for the region. All of the study participants were white
Caucasians and had a demographic composition similar to the 2011 national census population [27],
which also supports the findings. Among those who were refracted, the prevalence rate of myopia
(SER 0.5 D) was 24.1% and decreased from 28.7% in subjects aged 3559 years to 19.3% in those
aged 60 years or older. Our results were not far from the results of the epidemiological study on
older adults of predominantly European Caucasian origin performed in recent years in SpainThe
Segovia Study where myopia prevalence of 25.4% was found [11]. In addition our results were lower
than those reported in non-Hispanic whites in the 20052008 National Health and Nutrition
Examination Survey (NHANES) in the United States and in Japan, South Korea and among Chinese
in Singapore [15,19,24,32]. But were higher than those found among older adults in Australia,
predominantly of European Caucasian origin, in the Blue Mountains Eye Study and among
Figure 2. Histogram of hyperopic refractive error in the researched population.
3.3. Multiple Logistic Regression Modeling
Multivariate logistic regression models were constructed to analyze the risk factors for myopia
and hyperopia in this group (Table 3).
Table 3. Multiple logistic regression models of the risk factors for myopia and hyperopia.
Variables Myopia 0.5 D Hyperopia 0.5 D
OR, 95% CI, pValue OR, 95% CI, pValue
Age, per year increase 0.98 (0.96–1.00); p= 0.023 1.02 (1.00–1.04); p= 0.046
Women vs. men 1.87 (1.18–2.95); p= 0.007 2.16 (1.38–3.38); p= 0.001
Any cataract 2.40 (1.24–4.63); p= 0.009 1.68 (0.96–2.96); p= 0.070
Glaucoma and ocular hypertension (OHT) 0.36 (0.11–1.19); p= 0.094 0.52 (0.22–1.23); p= 0.136
Socioeconomic status 1.21 (0.35–4.14); p= 0.766 1.87 (0.62–5.63); p= 0.264
Our analysis showed that hyperopia was significantly associated with age (OR 1.02, 95% CI
1.00–1.04). Myopia was also significantly associated with age (OR 0.98, 95% CI 0.96–1.00) but in
opposite direction. After adjusting for all other factors women were more likely to have hyperopia (OR
2.16, 95% CI 1.38–3.38) compared with myopia (OR 1.87, 95% CI 1.18–2.95). The presence of cataract
was a significant risk factor for myopia (OR 2.40, 95% CI 1.24–4.63). No association was found between
refractive errors and socioeconomic status of our study subjects.
4. Discussion
This study describes refractive errors in a group of Polish citizens’ aged 35 years or older,
living in the city of Lodz in central Poland. It provides for the first time data concerning the
distribution of refractive errors and their characteristics for the region. All of the study participants
were white Caucasians and had a demographic composition similar to the 2011 national census
population [
27
], which also supports the findings. Among those who were refracted, the prevalence
rate of myopia (SER
0.5 D) was 24.1% and decreased from 28.7% in subjects aged 35–59 years to
19.3% in those aged 60 years or older. Our results were not far from the results of the epidemiological
study on older adults of predominantly European Caucasian origin performed in recent years in
Spain—The Segovia Study where myopia prevalence of 25.4% was found [
11
]. In addition our
results were lower than those reported in non-Hispanic whites in the 2005–2008 National Health
Int. J. Environ. Res. Public Health 2018,15, 90 6 of 10
and Nutrition Examination Survey (NHANES) in the United States and in Japan, South Korea and
among Chinese in
Singapore [15,19,24,32]
. But were higher than those found among older adults
in Australia, predominantly of European Caucasian origin, in the Blue Mountains Eye Study and
among African-Americans in Barbados, Chinese in Beijing or Taiwan and in studies from Nigeria,
Bangladesh and Argentina [
9
,
16
,
17
,
20
,
33
35
]. All these studies were population based and not hospital
based. Comparison of sampling techniques and the prevalence rates of refractive errors in different
populations from previously published studies is presented in Table 4.
Hyperopia (SER
0.5 D) was the most common refractive error in our study accounting for
37.5% and increased from 21.8% in subjects aged 35–59 years to 53.3% in those aged 60 years and
older. High rates of hyperopia prevalence were also found in older British adults in the EPIC-Norfolk
Eye Study [
25
] and in adult Americans in Beaver Dam Eye Study in Wisconsin [
22
]. The multiple
regression analysis showed that increasing age and female gender were significantly associated with
hyperopia. Factors associated with myopia were the same but age was associated in opposite direction.
Myopia was also positively associated with the presence of any cataract.
Our findings were in agreement with the results of some previous studies, which demonstrated a
decrease of the prevalence of myopia and, simultaneously, an increase in the prevalence of hyperopia
with increasing age [
3
,
10
,
11
,
23
]. The results of other studies also revealed that myopia was associated
with higher level of education, professional occupations requiring near-work, less outdoor activities as
well as with nuclear lens opacities and ocular dimensions [
2
,
8
,
10
,
36
]. Some studies showed hyperopia
was associated with age, female gender, lower educational level, non-professional occupations and
decreased axial length, though their findings were not consistent [
9
,
10
,
12
]. The distribution of
astigmatism in our study was higher in men and in age group 60 years and older. Anisometropia
greater than 1.0 D was found in 9.2% of subjects, which is comparable with the findings from Singapore,
Mongolia and Spain [11,12,37].
Correction of refractive errors across the world is one of the biggest challenges for public health.
Although refractive errors cannot be prevented, they can easily be diagnosed and corrected for a
relatively small costs. Limitations to the present study included differences in study design and
population sampling with possible presence of selection bias. We cannot directly compare our data
with other population-based studies. Patients enrolled into the study were solely from our Outpatients
Department thus the prevalence of ocular disorders might be higher than in general population. Other
limitation was that cycloplegic refraction data were collected only in subjects with VA < 20/40 Snellen
(0.3 logMAR).
Int. J. Environ. Res. Public Health 2018,15, 90 7 of 10
Table 4. Comparison of sampling techniques and the prevalence rates of refractive errors in different populations from previously published studies.
Epidemiological Study Sampling Technique Age Group (Years) Myopia (%) Hyperopia (%) Astigmatism (%) Anisometropia (%)
The Beaver Dam Eye Study (USA) [22] † a door to door census 43 26.2 49.0 NA NA
The Blue Mountains Eye Study (Australia) [20] † a door to door census 49 15.5 56.6 NA NA
The Tajimi Study (Japan) [15] † random sampling 40 41.8 27.9 54.0 15.1
The Gutenberg Health Study (Germany) [7] † random sampling 35 35.1 32.8 32.3 13.5
The Barbados Eye Study (Barbados) [9] † random sampling 40 21.9 46.9 NA NA
The Singapore Indian Eye Study (Singapore) [12] † age-stratified random sampling 40 28.0 35.9 54.9 9.8
The Segovia Study (Spain) [11] ‡ age-stratified random sampling 40 25.4 43.6 53.5 12.3
The Yazd Eye Study (Iran) [18] ‡ multistage random cluster sampling 40 36.5 20.6 53.8 11.9
Korean National Health and Nutrition
Examination Survey (South Korea) [19] § multistage stratified cluster random sampling 20 48.1 24.2 34.0 NA
The Nigerian National Blindness and Visual
Impairment Study (Nigeria) [33] † multistage stratified cluster random sampling 40 16.2 50.7 63.5 NA
The National Blindness and Low Vision Survey of
Bangladesh (Bangladesh) [34] †
cluster sampling and a door to
door enumeration 30 22.1 20.6 32.4 7.5
The Shihpai Eye Study (Taiwan) [17] † random sampling and a door to
door enumeration 65 19.4 59.0 74.0 21.8
Myopia (<
0.5 D), Hyperopia (>+0.5 D), Astigmatism (>0.5 cyl D), Anisometropia (>1.0 D).
Myopia (<
0.5 D), Hyperopia (>+0.5 D), Astigmatism (>0.5 cyl D), Anisometropia (
1.0 D).
§ Myopia (<0.5 D), Hyperopia (>+0.5 D), Astigmatism (>1.0 cyl D).
Int. J. Environ. Res. Public Health 2018,15, 90 8 of 10
5. Conclusions
In conclusion, this study provides for the first time epidemiologic data on refractive status of
individuals aged 35 years and older in Poland. The distribution of refractive errors found in our
study is similar to those reported in other Caucasian populations in Western Europe and America,
but differs from Asian populations. In our study population myopia was positively associated with
younger age, female gender and presence of any cataract. To the best of our knowledge the distribution
and characteristic of refractive errors among European Caucasian adults in Eastern Europe have
not been previously reported. However, further investigations are needed on a larger, randomly
selected populations.
Acknowledgments:
Authors thank Rafael Iribarren from Department of Ophthalmology Centro Médico San Luis,
Buenos Aires, Argentina and Seang Mei Saw, MBBS, MPH, PhD, FAMS, FARVO Saw Swee Hock School of Public
Health, National University of Singapore for the critical discussion of our work.
Author Contributions:
Michal S. Nowak conceived and designed the experiments. Data was collected by
Michal S. Nowak
and the results were analyzed by Janusz Smigielski. The first and final drafts were written by
Michal S. Nowak. The defects of draft were critiqued by Piotr Jurowski and Andrzej Grzybowski. All authors
agreed on the final draft of this study.
Conflicts of Interest: The authors declare no conflict of interest.
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article distributed under the terms and conditions of the Creative Commons Attribution
(CC BY) license (http://creativecommons.org/licenses/by/4.0/).
... According to the estimates of the World Health Organization (WHO), 285 million people are visually impaired including 246 million having low vision and 39 million blind (2). Diverse community-based studies of uncorrected refractive errors (URE) in different countries conclude a prevalence of 22.3% in China, 17.3% in Singapore, 17.1% in Malaysia, 15.8% in Chile, 10.2% in Australia, 10.2% in Bangladesh, and 6% in the United States, respectively (3). However, in contrast to the above-mentioned prevalence, a school-based study among the students aged 5-16 years from Rawalpindi reported a prevalence of 3.35% (4). ...
... It is estimated that out of 2.3 billion people with refractive errors only 1.8 billion can have the access to affordable ophthalmic examination and their correction worldwide (14). So, accessibility and affordability are major problems but it is also worth mentioning that the management of these errors is considered among the most cost-effective interventions in health care (15). ...
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... Tokoro [11] (2.16%), and Lai et al [17] (11.3%). However, a possible reason is that this reflects the higher prevalence of myopia (69.6%) in our office workers (aged 21-59y), which was less than 2 fold higher than the rate seen in Singapore (38.7%; aged 40-79y) [18] and 2.5 fold higher than Poland (24.1%; aged 35y and older) [19] . As expected, the prevalence of peripheral myopic retinopathy in our study increased significantly (P<0.001) with the level of myopia [5] , from 15.0% in eyes with mild myopia to 25.1% and 49.4% in eyes with moderate and high myopia, respectively. ...
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To investigate the prevalence and causes of visual impairment and blindness in a sample of Polish older adults. The study was designed in a cross-sectional and observational manner. Data concerning the vision status were assessed in 2214 eyes from 1107 subjects of European Caucasian origin; most of whom live in the city of Lodz, in central Poland. Visual impairment was defined as distance visual acuity <20/40 in the worse-seeing eye. Low vision was defined as best-corrected visual acuity (BCVA) <20/40 but >20/200 in better-seeing eye, and blindness was defined as BCVA ≤20/200 in both eyes (United States criteria). Visual impairment was found in 27.5% subjects in the worse-seeing eye. Multiple regression analysis showed that increasing age (OR 0.98, 95% CI 0.97–0.99) and female gender (OR 1.47, 95% CI 1.11–1.93) were independent risk factors. No association was found between visual impairment and socioeconomic status of subjects. Noncorrectable visual impairment was found in 7.0% of subjects, including 5.2% of subjects with unilateral and 1.8% of subjects with bilateral visual impairment. Low vision and blindness accounted for 1.3% and 0.5%, respectively, and were only associated with older age (OR 1.05, 95% CI 1.02–1.10). Retinal diseases represented the major cause of noncorrectable visual impairment and accounted for more than half of causes of blindness. Provision of appropriate refractive correction improves visual acuity in 75% subjects presenting with visual impairment. Retinal diseases are a major cause of noncorrectable visual impairment and blindness in this older population.
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Objetivo Determinar la prevalencia de las condiciones refractivas en la población adulta que acudió a centros de atención optométrica visual primaria en Puerto Rico. Métodos Estudio retrospectivo transversal de pacientes examinados en las clínicas oculares de la Escuela de Optometría de la Universidad Interamericana de Puerto Rico entre 2004 y 2010. Los pacientes examinados presentaban una agudeza visual corregida mediante refracción subjetiva estandarizada de 20/40 o más. Los errores refractivos se clasificaron mediante el equivalente esférico (EE): esfera+½ cilindro. La miopía se clasificó como EE>−0.50 D, la hipermetropía como EE>+0.50 D, y la emetropía como EE entre -0,50 y +0,50. El astigmatismo igual o superior a 0,25 D se consideró utilizando la notación de cilindro negativo. Se excluyó del estudio a los pacientes con antecedentes de cirugía de cataratas (pseudofaquia o afaquia), ambliopía, cirugía refractiva u otras cirugías corneales/oculares. Resultados Se seleccionó a un total de 784 pacientes mayores de 40 años, elegidos al azar. Las prevalencias estimadas (95%, intervalo de confianza) entre los sujetos examinados fueron: hipermetropía 51,5% (48,0-55,0), emetropía 33,8% (30,5-37,2), miopía 14,7% (12,1-17,2) y astigmatismo 69,6% (68,8-73,3). La hipermetropía fue más común en mujeres que en hombres, aunque la diferencia entre sexos no fue estadísticamente significativa. Los valores del equivalente esférico medio se decantaron hacia la hipermetropía hasta los 70 y/o,disminuyendo ligeramente a medida que la población envejecía. Conclusión La hipermetropía constituye el error refractivo más común, pareciendo incrementarse su prevalencia con la edad en la población que visitó la clínica. Deberán desarrollarse más programas y estudios para evaluar las necesidades de corrección visual de la población adulta de Puerto Rico.
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To study the distribution of refractive errors among adults of European descent. Population-based eye study in Germany with15 010 participants aged 35-74 years. The study participants underwent a detailed ophthalmic examination according to a standardised protocol. Refractive error was determined by an automatic refraction device (Humphrey HARK 599) without cycloplegia. Definitions for the analysis were myopia <-0.5 dioptres (D), hyperopia >+0.5 D, astigmatism >0.5 cylinder D and anisometropia >1.0 D difference in the spherical equivalent between the eyes. Exclusion criterion was previous cataract or refractive surgery. 13 959 subjects were eligible. Refractive errors ranged from -21.5 to +13.88 D. Myopia was present in 35.1% of this study sample, hyperopia in 31.8%, astigmatism in 32.3% and anisometropia in 13.5%. The prevalence of myopia decreased, while the prevalence of hyperopia, astigmatism and anisometropia increased with age. 3.5% of the study sample had no refractive correction for their ametropia. Refractive errors affect the majority of the population. The Gutenberg Health Study sample contains more myopes than other study cohorts in adult populations. Our findings do not support the hypothesis of a generally lower prevalence of myopia among adults in Europe as compared with East Asia.
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Myopia is one of the most prevalent disorders of the eye. Higher myopia is associated with comorbidities that increase risks of severe and irreversible loss of vision, such as retinal detachment, subretinal neovascularization, dense cataract, and glaucoma. In recent years, reports from population-based prevalence studies carried out in various geographical areas now give a clear picture of the current distribution of refractive error. The scarcity of data from well-designed longitudinal cohort studies is still yet to be addressed. These studies have confirmed the previous data indicating that prevalence of refractive error varies according to ethnicity and geographic regions, and also point to an increase in myopia prevalence over the past half-century. The problem is particularly pronounced in affluent, industrialised areas of East Asia. Environmental risk factors for myopia related to socioeconomic status and lifestyle have been identified. The past decade has seen a greater understanding of the molecular biological mechanisms that determine refractive error, giving further support to the belief that myopia is the result of a complex interaction between genetic predisposition and environmental exposures. This review summarizes data on the prevalence, incidence, progression, associations, risk factors, and impact from recent epidemiological studies on myopia.Eye advance online publication, 10 January 2014; doi:10.1038/eye.2013.280.
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To determine the prevalence of refractive errors in Yazd, central Iran. This population-based study was performed in 2010-2011 and targeted adults aged 40 to 80 years. Multi-stage random cluster sampling was applied to select samples from urban and rural residents of Yazd. Manifest refraction, visual acuity measurement, retinoscopy and funduscopy were performed for all subjects. Myopia, hyperopia, astigmatism and anisometropia were defined as spherical equivalent (SE) <-0.50 diopters (D), SE >+0.50 D, cylindrical error >0.5 D and SE difference ≥1 D between fellow eyes, respectively. From a total of 2,320 selected individuals, 2,098 subjects (90.4%) participated out of which 198 subjects were excluded due to previous eye surgery. The prevalence (95% confidence interval) for myopia, hyperopia, astigmatism, anisometropia, -6 D myopia or worse, and 4 D hyperopia or worse was 36.5% (33.6-39.4%), 20.6% (17.9-23.3%), 53.8% (51.3-56.3%), 11.9% (10.4-13.4%), 2.3% (1.6-2.9%) and 1.2% (0.6-1.8%), respectively. The prevalence of hyperopia, astigmatism and anisometropia increased with age. The prevalence of myopia was significantly higher in female subjects. The prevalence of with-the-rule, against-the-rule and oblique astigmatism was 35.7%, 13.4% and 4.6%, respectively. The prevalence of against-the-rule astigmatism increased with age (P<0.001); with-the-rule astigmatism was more common in women (P=0.038). More than half of the study population had refractive errors; the prevalence of myopia and astigmatism was higher than earlier studies in Iran. Since refractive errors are a major cause of avoidable visual impairment, their high prevalence in this survey is important from a public health perspective.
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To examine the prevalence and risk factors of refractive errors in a representative Korean population aged 20 years old or older. A total of 23,392 people aged 20+ years were selected for the Korean National Health and Nutrition Survey 2008-2011, using stratified, multistage, clustered sampling. Refractive error was measured by autorefraction without cycloplegia, and interviews were performed regarding associated risk factors including gender, age, height, education level, parent's education level, economic status, light exposure time, and current smoking history. Of 23,392 participants, refractive errors were examined in 22,562 persons, including 21,356 subjects with phakic eyes. The overall prevalences of myopia (< -0.5 D), high myopia (< -6.0 D), and hyperopia (> 0.5 D) were 48.1% (95% confidence interval [CI], 47.4-48.8), 4.0% (CI, 3.7-4.3), and 24.2% (CI, 23.6-24.8), respectively. The prevalence of myopia sharply decreased from 78.9% (CI, 77.4-80.4) in 20-29 year olds to 16.1% (CI, 14.9-17.3) in 60-69 year olds. In multivariable logistic regression analyses restricted to subjects aged 40+ years, myopia was associated with younger age (odds ratio [OR], 0.94; 95% Confidence Interval [CI], 0.93-0.94, p < 0.001), education level of university or higher (OR, 2.31; CI, 1.97-2.71, p < 0.001), and shorter sunlight exposure time (OR, 0.84; CI, 0.76-0.93, p = 0.002). This study provides the first representative population-based data on refractive error for Korean adults. The prevalence of myopia in Korean adults in 40+ years (34.7%) was comparable to that in other Asian countries. These results show that the younger generations in Korea are much more myopic than previous generations, and that important factors associated with this increase are increased education levels and reduced sunlight exposures.
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Background: Refractive errors are among the most frequent reasons for demand of eye-care services. Publications on refractive errors prevalence in our country are few. This study has the purpose to assess the prevalence of refractive errors in an adult population of Villa Maria, Córdoba, Argentina. Methods: The Villa Maria Eye Study is a population-based cross-sectional study conducted in the city of Villa Maria, Córdoba, Argentina from May 2008 to November 2009. Subject’s aged 40+ received a demographic interview and complete ophthalmological exam. Visual acuity was obtained with an ETDRS chart. Cycloplegic auto refraction was performed. The spherical equivalent was highly correlated between right and left eyes, so only data of right eyes are presented. Myopia and hyperopia were defined with a ±0.50 diopters (D) criterion and astigmatism >1 D. Results: This study included 646 subjects, aged 40 to 90 (mean age: 59.6±10.3 years old). Four hundred and sixty two (71.5%) were females. The mean spherical equivalent was +0.714±2.41 D (range, −22.00 to +8.25 D) and the power of the cylinder was, on average, −0.869±0.91 D (range, 0 to −6.50 D). In this sample, 61.6% subjects were hyperopic, and 13.5% were myopic. Myopia prevalence was lower in men (9.8% versus 14.9%) but this difference among genders was not statistically significant. There were 141 subjects (21.8%) with anisometropia greater than 1 D, and 168 subjects (26.0%) with astigmatism greater than 1 D. Conclusions: The present study shows the prevalence of cycloplegic refractive errors in an adult population of Argentina. The prevalence of hyperopia was high, while myopia prevalence was very low.
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Background: To assess five-year refractive changes and their related factors in the 40-64 year old population of Shahroud, Iran. Design: Prospective cohort study. Participants: Of the 5190 participants of Phase I 4737 participated in Phase II (response rate =91.3%). Methods: Participants were tested by refraction, visual acuity, slit-lamp biomicroscopy, ophthalmoscopy, and biometry. Myopia was defined as a spherical equivalent more negative than -0.5 diopters, and hyperopia as a spherical equivalent more positive than +0.5 diopters. Main outcome measures: Mean 5-year change in spherical equivalent refraction. Results: The mean 5-year change in spherical equivalent refraction was +0.24D (95% CI: +0.22 to +0.25). After 5 years, 4.77% (95% CI: 4.08 to 5.46) of subjects developed at least 0.5D of myopia, and 22.27% (95% CI: 20.97 to 23.57) developed at least 0.5D of hyperopia. Five-year changes in refraction included an hyperopic shift in all age groups. The greatest hyperopic shift was seen in middle aged women. The greatest loss of lens power was observed in hyperopic women, and the least in myopic men. Nuclear cataract was associated with a myopic shift in refraction. The axial length and the corneal power had very small changes during this period. Myopes showed the greatest increase in axial length. Corneal power increased by a very small amount in all refractive groups. Conclusions: The most important biometric index related to hyperopic shifts, which were greater in magnitude in women, was loss of lens power, whereas nuclear cataract was associated with myopic shifts.