ANNALES ACADEMIAE MEDICAE STETINENSIS
ROCZNIKI POMORSKIEJ AKADEMII MEDYCZNEJ W SZCZECINIE
2008, 54, 1, 17–21
DAMIAN CZEPITA, ARTUR MOJSA, MARIA ŻEJMO1
PREVALENCE OF MYOPIA AND HYPEROPIA AMONG URBAN AND RURAL
SCHOOLCHILDREN IN POLAND
CZĘSTOŚĆ WYSTĘPOWANIA KRÓTKOWZROCZNOŚCI I NADWZROCZNOŚCI
WŚRÓD UCZNIÓW MIEJSKICH I WIEJSKICH W POLSCE
Katedra i Klinika Okulistyki Pomorskiej Akademii Medycznej w Szczecinie
al. Powstańców Wlkp. 72, 70-111 Szczecin
Kierownik: prof. dr hab. n. med. Danuta Karczewicz
1
Katedra i Zakład Mikrobiologii i Immunologii Pomorskiej Akademii Medycznej w Szczecinie
al. Powstańców Wlkp. 72, 70-111 Szczecin
Kierownik: prof. dr hab. n. med. Stefania Giedrys-Kalemba
Streszczenie
Wstęp: Krótkowzroczność i nadwzroczność mają duże
znaczenie kliniczne ponieważ mogą prowadzić do obniżenia
ostrości wzroku, a nawet do ślepoty. Dlatego też istnieje duże zapotrzebowanie na wszelkie badania kliniczne
dotyczące rozwoju oka oraz powstawania wad refrakcji.
Pomimo tego do tej pory na świecie nie opublikowano zbyt
wielu prac porównujących częstość występowania krótkowzroczności i nadwzroczności wśród uczniów miejskich
i wiejskich, natomiast w Polsce nie opublikowano żadnej.
Dlatego celem pracy było opisanie częstości występowania
krótkowzroczności i nadwzroczności wśród dzieci miejskich
i wiejskich w Polsce.
Materiał i metody: Przebadano 2206 uczniów (1155
chłopców i 1051 dziewcząt w wieku 10–14 lat, średni wiek
11,9 lat, SD = 1,4). 614 chłopców w wieku 11,8 lat (SD = 1,4)
mieszkało w mieście, a 541 chłopców w wieku 11,9 lat
(SD = 1,4) mieszkało na wsi. 586 dziewcząt w wieku 11,8
lat (SD = 1,5) mieszkało w mieście, a 465 dziewcząt w wieku 11,9 lat (SD = 1,4) mieszkało na wsi. Badani uczniowie
należeli do rasy kaukaskiej, mieszkali w Szczecinie lub na
wsiach w pobliżu Szczecina. Wykonywano skiaskopię po
cykloplegii. Wyniki wad refrakcji wyrażono w formie ekwiwalentu sferycznego (SE). Przyjęto, że w krótkowzroczności
SE < -0,5 D, a w nadwzroczności SE > +1,5 D. Astygmatyzm
wśród uczniów z krótkowzrocznością i nadwzrocznością
był mniejszy od 1 DC. Analizę danych przeprowadzono
testem χ2. Przyjęto poziom istotności p < 0,05.
Wyniki: Zaobserwowano, że krótkowzroczność występuje częściej u dzieci mieszkających w mieście niż na wsi.
Krótkowzroczność miało 13,9% uczniów miejskich oraz
7,5% wiejskich (p < 0,001) – tabela 1. Poza tym stwierdzono,
że nadwzroczność występuje rzadziej u dzieci mieszkających
w mieście niż na wsi. Nadwzroczność miało 7,1% uczniów
miejskich i 30,8% wiejskich (p < 0,001) – tabela 2. Wykazano, że średnia wada refrakcji jest niższa wśród dzieci
z miasta niż ze wsi – tabela 3.
Wniosek: Mieszkanie w środowisku miejskim lub wiejskim może wpływać na występowanie krótkowzroczności
i nadwzroczności wśród uczniów.
H a s ł a: krótkowzroczność − nadwzroczność − miasto −
wieś − uczniowie.
Summary
Introduction: Myopia and hyperopia have a significant
clinical meaning as they can be the cause of low visual acuity or even blindness. Therefore, there is a high demand for
all clinical investigations regarding the development of the
eye and the creation of refractive errors. Nevertheless, not
many papers have been published around the world which
18
DAMIAN CZEPITA, ARTUR MOJSA, MARIA ŻEJMO
compared the prevalence of myopia as well as hyperopia
among metropolitan and provincial schoolchildren. Whereas,
in Poland there was not a single paper yet published concerning this topic. That is why the aim of this paper is to
describe the prevalence of myopia and hyperopia among
urban and rural schoolchildren in Poland.
Material and methods: 2206 students were examined
1155 boys and 1051 girls, aged 10−14 years, mean age 11.9
(SD = 1.4). 614 boys in the age of 11.8 years (SD = 1.4) lived
in the city, as 541 boys in the age of 11.9 years (SD = 1.4)
lived in the countryside. 586 girls in the age of 11.8 years
(SD = 1.5) lived in the city, as 465 girls in the age of 11.9
years (SD = 1.4) lived in the countryside. The examined
students were Caucasian and lived in Szczecin, Poland or in
villages located near Szczecin. The examination included
retinoscopy under cycloplegia. The refractive error readings were expressed as spherical equivalent (SE). Myopia
was defined as SE of at least -0.5 D, hyperopia as SE of
at least +1.5 D. Astigmatism among students with myopia
and hyperopia was smaller than 1 DC. Data analysis was
performed using χ2 test. P values of less than 0.05 were
considered statistically significant.
Results: It was observed that myopia occurred more
frequently among children living in the city than in the
countryside. 13.9% urban and 7.5% rural schoolchildren
had myopia (p < 0.001) – table 1. Furthermore, it was found
that hyperopia is less frequent among children living in
the city than in the countryside. 7.1% urban and 30.8%
rural students had hyperopia (p < 0.001) – table 2. It was
determined that the average refractive error is lower among
children from the city than the countryside – table 3.
Conclusion: Living in an urban or a rural environment
may have an influence on the occurrence of myopia and
hyperopia among schoolchildren.
K e y w o r d s: myopia − hyperopia − urban − rural −
schoolchildren.
Introduction
Lately, a major increase in the frequency of myopia occurrence has been noted. This refractive error occurs more
frequently in East Asia and countries with a high level of
technological development. Hence, this can be linked on
one side with genetic predispositions as on the other with
the influence of the environment [1, 2, 3, 4, 5, 6, 7].
Among the environmental factors near visual work
which is reading, writing, as well as working on the computer
play the most important role. It is believed that other environmental factors especially like whether we live in a city
or a village play a lesser role in the creation and progress of
myopia. That is why not a lot of attention has been focused
on them [1, 2, 5, 6, 7].
On the other hand hyperopia prevalent among children
is in a lesser degree linked with the influence of the envi-
ronment. Children are born with physiological hyperopia.
With age the optical components in the eyeball change, and
hyperopia gradually decreases [1, 3, 4].
Myopia and hyperopia have a significant clinical meaning as they can be the cause of low visual acuity or even
blindness. Therefore, there is a high demand for all clinical
investigations regarding the development of the eye and the
creation of refractive errors [1, 2, 5, 7].
Nevertheless, not many papers have been published
around the world which compared the prevalence of myopia
as well as hyperopia among metropolitan and provincial
schoolchildren [8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
21, 22, 23, 24]. Whereas, in Poland there was not a single
paper yet published concerning this topic.
That is why the aim of this paper is to describe the
prevalence of myopia and hyperopia among urban and rural
schoolchildren in Poland.
Material and methods
2206 students were examined (1155 boys and 1051 girls,
aged 10−14 years, mean age 11.9, SD = 1.4). 614 boys in
the age of 11.8 years, SD = 1.4 lived in the city, as 541 boys
in the age of 11.9 years, SD = 1.4 lived in the countryside.
586 girls in the age of 11.8 years, SD = 1.5 lived in the city,
as 465 girls in the age of 11.9 years, SD = 1.4 lived in the
countryside.
The examined children, students of elementary and
secondary schools, were examined in the school’s consulting rooms. The examined students were Caucasian
and lived in Szczecin, Poland or in villages located near
Szczecin.
Participation was voluntary and informed consent was
obtained from the school principals and parents of all the
children. The studies were approved by the Bioethics Committee of the Pomeranian Medical University. The research
protocol adhered to the provisions of the Declaration of
Helsinki for research involving human subjects.
The examination included retinoscopy under cycloplegia induced with two drops of 1% tropicamide instilled
5 minutes apart to each eye. Thirty minutes after the last
drop retinoscopy was performed.
Retinoscopy was performed in a dark room and all
schoolchildren were examined by the some doctor (AM).
According to Zadnik et al. [25] 95% limits of agreement
for cycloplegic retinoscopy are + 0.95 D.
The refractive error readings were expressed as spherical
equivalent (SE) (sphere power plus half negative cylinder
power). Myopia was defined as SE of at least -0.5 D, hyperopia as SE of at least +1.5 D. Astigmatism among students
with myopia and hyperopia was smaller than 1 DC. Both
eyes were examined though data gathered from the right
eye were analyzed.
Data analysis was performed using χ2 test. P values of
less than 0.05 were considered statistically significant.
19
PREVALENCE OF MYOPIA AND HYPEROPIA AMONG URBAN AND RURAL SCHOOLCHILDREN IN POLAND
Results
Discussion
It was observed that myopia occurred more frequently
among children living in the city than in the countryside.
13.9% urban and 7.5% rural schoolchildren had myopia
(p < 0.001) – table 1.
Furthermore, it was found that hyperopia is less frequent among children living in the city than in the countryside. 7.1% urban and 30.8% rural students had hyperopia
(p < 0.001) – table 2.
It was determined that the average refractive error is lower
among children from the city than the countryside – table 3.
Although the environmental conditions have a big influence on the creation and progress of myopia until now
only a few works have came out in which a comparison
in the prevalence of myopia as well as hyperopia in the
countryside and in the city has been done [8, 9, 10, 11, 12,
13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24].
The first studies concerning this matter have been carried out in 1963–1983 in India. It was than found that myopia
occurs more frequently among the urban population and
people with higher education and higher income [17].
T a b l e 1. Prevalence of myopia (SE < -0.5 D) among urban and rural schoolchildren in Poland
T a b e l a 1. Częstość występowania krótkowzroczności (SE < -0,5 D) wśród uczniów miejskich i wiejskich w Polsce
Age
(years)
Wiek
(lata)
10
11
12
13
14
Total
Razem
Urban children / Dzieci miejskie
examined group
badana grupa
N
314
241
203
235
207
with myopia
z krótkowzrocznością
N
%
37
11.8
27
11.2
26
12.8
35
14.9
42
20.3
1200
167
Urban – Rural children
Dzieci miejskie – wiejskie
Rural children / Dzieci wiejskie
13.9
examined group
badana grupa
N
222
197
216
220
151
with myopia
z krótkowzrocznością
N
%
14
6.3
10
5.1
21
9.7
20
9.1
10
6.6
1006
75
7.5
difference
różnica
%
5.5
6.1
3.1
5.8
13.7
< 0.05
< 0.05
> 0.05
> 0.05
< 0.001
6.4
< 0.001
p
T a b l e 2. Prevalence of hyperopia (SE > +1.5 D) among urban and rural schoolchildren in Poland
T a b e l a 2. Częstość występowania nadwzroczności (SE > +1,5 D) wśród uczniów miejskich i wiejskich w Polsce
Age
(years)
Wiek
(lata)
10
11
12
13
14
Total
Razem
Urban children / Dzieci miejskie
examined group
badana grupa
N
314
241
203
235
207
with hyperopia
z nadwzrocznością
N
%
26
8.3
10
4.1
20
9.9
18
7.7
11
5.3
1200
85
Urban – Rural children
Dzieci miejskie – wiejskie
Rural children / Dzieci wiejskie
7.1
examined group
badana grupa
N
222
197
216
220
151
1006
with hyperopia
z nadwzrocznością
N
%
74
33.3
56
28.4
58
26.9
67
30.5
55
36.4
310
30.8
difference
różnica
%
-25.0
-24.3
-17.0
-22.8
-31.1
< 0.001
< 0.001
< 0.001
< 0.001
< 0.001
-23.7
< 0.001
p
T a b l e 3. Average refractive error among urban and rural schoolchildren in Poland
T a b e l a 3. Średnia wada refrakcji wśród uczniów miejskich i wiejskich w Polsce
Age (years)
Wiek (lata)
10
11
12
13
14
Total
Razem
Urban children / Dzieci miejskie
examined group
badana grupa
N
314
241
203
235
207
1200
Rural children / Dzieci wiejskie
mean
średnia
SD
0.3
0.1
0.2
0.1
0.1
0.8
0.7
0.8
1.5
0.8
examined group
badana grupa
N
222
197
216
220
151
0.2
1.0
1006
Urban – Rural children
Dzieci miejskie – wiejskie
mean
średnia
SD
mean / średnia
0.9
1.0
0.9
0.9
1.0
1.4
1.0
1.1
1.0
1.2
-0.6
-0.9
-0.7
-0.8
-0.9
1.0
1.1
-0.8
20
DAMIAN CZEPITA, ARTUR MOJSA, MARIA ŻEJMO
T a b l e 4. Prevalence of myopia (SE < -0.5 D) and hyperopia (SE > + 2.0 D) among schoolchildren of different countries
T a b e l a 4. Częstość występowania krótkowzroczności (SE < -0,5 D) i nadwzroczności (SE > + 2,0 D) wśród uczniów różnych krajów
Authors
Autorzy
Maul et al.
2000
Pokharel et al.
2000
Zhao et al.
2000
Dandona et al.
2002
Murthy et al.
2002
Naidoo et al.
2003
He et al.
2004
Goh et al.
2005
Country
Kraj
Chile
Chile
Nepal
Nepal
China
Chiny
India
Indie
India
Indie
South Africa
RPA
China
Chiny
Malaysia
Malezja
Area / Środowisko
Age (years)
Wiek (lata)
Myopia (%)
Krótkowzroczność (%)
Hyperopia (%)
Nadwzroczność (%)
Urban / Miejskie
5−15
6.8
16.3
Rural / Wiejskie
5−15
1.2
1.4
Rural / Wiejskie
5−15
16.2
3.5
Rural / Wiejskie
7−15
4.1
0.8
Urban / Miejskie
5−15
7.4
7.7
Semirural/urban
Podmiejskie/miejskie
5−15
2.9
1.8
Urban / Miejskie
5−15
35.1
0.8
Urban / Miejskie
7−15
19.3
1.3
In 1970 Said et al. [21] described the prevalence and
causes of blindness in urban and rural areas of Egypt. In all
they had examined 10 984 people from and around Alexandria. They have proven that myopia occurs more frequently
in the city than the countryside and is the third ranking
cause of blindness among urban residents.
Extensive epidemiological studies on the prevalence of
myopia were carried out in the years 1983−2000 in Taiwan.
All together 45 359 students have been examined and it was
observed that myopia occurs more frequently in metropolitan
than in provincial schools located in Taiwan. This correlation
was justified by a lot of near-work activity among students
of city schools [8, 13, 14].
In 1999−2001 results of several studies done in rural
and urban areas of China, Nepal and the Sultanate of Oman
have been published. In those studies it was also found that
myopia occurs more frequently among students from the
city rather than from the countryside and is associated with
intensive near-work as well as having a father with higher
levels of education [10, 15, 22].
Recently, a series of population-based surveys of refractive errors and visual impairment among schoolchildren
(Refractive Error Study in Children – RESC) were conducted in several different countries, all using the same
protocol [26]. The results of these studies show that myopia
has a higher prevalence among urban students than in rural schoolchildren. However, the occurrence of hyperopia
among metropolitan students is lower than in provincial
schoolchildren [9, 11, 12, 16, 18, 19, 20, 24] – table 4.
Only in studies carried out in Australia Wensor et al.
[23] have shown that there was no significant difference
in myopia rates between urban and rural populations. Although, this was probably because the authors examined
subjects in the ages of 40−98 years old but not school age
children. However, a more frequent occurrence of myopia
was observed among people with higher education, clerks,
professionals, people born in southeast Asia, and people
with high degrees of nuclear opacity.
On the whole the majority of authors come to similar
conclusions and state that myopia occurs more frequently in
metropolitan schools than in provincial. It is assumed that
this is caused by more intensive near-work among urban
than rural schoolchildren [8, 9, 10, 11, 12, 13, 14, 15, 16, 17,
18, 19, 20, 21, 22, 23, 24].
This dependency was also observed in the carried out
work. Perhaps it might have been caused by the increased
intensiveness of visual work among students living in the
city. Additionally it was found that the average refractive
error is lower among urban than rural schoolchildren. As
this might be linked with the functioning of genetic factors
rather than environmental.
Conclusion
Living in an urban or a rural environment may have
an influence on the occurrence of myopia and hyperopia
among schoolchildren.
Acknowledgments
We would like to thank A. Pechmann for assistance
during data collection.
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