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Six Year Refractive Change among White Children and Young Adults: Evidence for Significant Increase in Myopia among White UK Children

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OBJECTIVE:To determine six-year spherical refractive error change among white children and young adults in the UK and evaluate differences in refractive profiles between contemporary Australian children and historical UK data. DESIGN:Population-based prospective study. PARTICIPANTS:The Northern Ireland Childhood Errors of Refraction (NICER) study Phase 1 examined 1068 children in two cohorts aged 6-7 years and 12-13 years. Prospective data for six-year follow-up (Phase 3) are available for 212 12-13 year olds and 226 18-20 year olds in each cohort respectively. METHODS:Cycloplegic refractive error was determined using binocular open-field autorefraction (Shin-Nippon NVision-K 5001, cyclopentolate 1%). Participants were defined by spherical equivalent refraction (SER) as myopic SER ≤-0.50D, emmetropic -0.50D
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RESEARCH ARTICLE
Six Year Refractive Change among White
Children and Young Adults: Evidence for
Significant Increase in Myopia among White
UK Children
Sara J. McCullough*
, Lisa ODonoghue
, Kathryn J. Saunders
Biomedical Sciences Research Institute, School of Biomedical Sciences, University of Ulster, Cromore Road,
Coleraine, N. Ireland, United Kingdom
These authors contributed equally to this work.
*sj.mccullough@ulster.ac.uk
Abstract
Objective
To determine six-year spherical refractive error change among white children and young
adults in the UK and evaluate differences in refractive profiles between contemporary Aus-
tralian children and historical UK data.
Design
Population-based prospective study.
Participants
The Northern Ireland Childhood Errors of Refraction (NICER) study Phase 1 examined
1068 children in two cohorts aged 67 years and 1213 years. Prospective data for six-year
follow-up (Phase 3) are available for 212 1213 year olds and 226 1820 year olds in each
cohort respectively.
Methods
Cycloplegic refractive error was determined using binocular open-field autorefraction (Shin-
Nippon NVision-K 5001, cyclopentolate 1%). Participants were defined by spherical equiva-
lent refraction (SER) as myopic SER -0.50D, emmetropic -0.50D<SER<+2.00 or hyper-
opic SER+2.00D.
Main Outcome Measures
Proportion and incidence of myopia.
PLOS ONE | DOI:10.1371/journal.pone.0146332 January 19, 2016 1/19
OPEN ACCESS
Citation: McCullough SJ, ODonoghue L, Saunders
KJ (2016) Six Year Refractive Change among White
Children and Young Adults: Evidence for Significant
Increase in Myopia among White UK Children. PLoS
ONE 11(1): e0146332. doi:10.1371/journal.
pone.0146332
Editor: Haotian Lin, Sun Yat-sen University, CHINA
Received: August 21, 2015
Accepted: December 14, 2015
Published: January 19, 2016
Copyright: © 2016 McCullough et al. This is an open
access article distributed under the terms of the
Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any
medium, provided the original author and source are
credited.
Data Availability Statement: All relevant data are
within the paper and its Supporting Information files.
Funding: This work was supported by The College of
Optometrists, London, UK Grant name: The Northern
Ireland Childhood Errors of Refraction Study Phase
3 Refractive development in childhood and early
adulthood. http://www.college-optometrists.org. The
funders had no role in study design, data collection
and analysis, decision to publish, or preparation of
the manuscript.
Competing Interests: The authors have declared
that no competing interests exist.
Results
The proportion of myopes significantly increased between 67 years (1.9%) and 1213
years (14.6%) (p<0.001) but not between 1213 and 1820 years (16.4% to 18.6%, p=
0.51). The estimated annual incidence of myopia was 2.2% and 0.7% for the younger and
older cohorts respectively. There were significantly more myopic children in the UK at age
1213 years in the NICER study (16.4%) than reported in Australia (4.4%) (p<0.001). How-
ever by 17 years the proportion of myopia neared equivalence in the two populations
(NICER 18.6%, Australia 17.7%, p= 0.75). The proportion of myopic children aged 1213
years in the present study (20062008) was 16.4%, significantly greater than that reported
for children aged 1016 years in the 1960s (7.2%, p= 0.01). The proportion of hyperopes
in the younger NICER cohort decreased significantly over the six year period (from 21.7%
to 14.2%, p= 0.04). Hyperopes with SER +3.50D in both NICER age cohorts demon-
strated persistent hyperopia.
Conclusions
The incidence and proportion of myopia are relatively low in this contemporary white UK pop-
ulation in comparison to other worldwide studies. The proportion of myopes in the UK has
more than doubled over the last 50 years in children aged between 1016 years and children
are becoming myopic at a younger age. Differences between the proportion of myopes in the
UK and in Australia apparent at 1213 years were eliminated by 17 years of age.
Introduction
There is a growing body of evidence suggesting that myopia is becoming more prevalent in
childhood in many areas of the world, such as in Taiwan, [1] Singapore, [2] the United States
[3] and Australia [4] while estimates of hyperopia prevalence remain relatively static.[4,5]
Although myopia prevalence has been much studied, few prospective studies are available
from which to derive estimates of incidence of myopia, the stability of hyperopia or to explore
individual change in refractive error.[4,611] The present study reports the six-year change in
refractive error status within a white, UK based population of children and young adults;
exploring both the incidence of myopia and the stability of hyperopia in pre-teenage children,
teenage children and young adults. Robust sampling and methodology similar to that used in
other large-scale studies of refractive error [12,13] have been employed. Comparisons will be
made with the recent report of six-year change in an Australian population of European Cau-
casian children [4] to determine geographical differences in an ethnically similar group and
with historical data [14] to evaluate whether the refractive profile of UK school children and
young adults has changed over the past 50 years.
Materials and Methods
The Northern Ireland Childhood Errors of Refraction (NICER) Study is a longitudinal study of
refractive error. The study methods have previously been described in detail [15] In brief,
Phase 1 of the NICER study was a cross-sectional epidemiological study investigating the prev-
alence of refractive error in 67 and 1213 year old children in Northern Ireland conducted
between 2006 and 2008. Participants were chosen using stratified random sampling of schools
Six Year Refractive Change in the UK - The NICER Study
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from geographic areas characteristic of Northern Ireland to obtain a representative sample of
schools and children from urban/rural and deprived/non-deprived areas. Data collection
included cycloplegic autorefraction using the binocular open-field autorefractor (SRW-5000,
Shin-Nippon, Tokyo, Japan). Cycloplegia was induced by one drop of 1.0% cyclopentolate
hydrochloride, after corneal anaesthesia with one drop of 0.5% proxymetacaine hydrochloride.
Autorefraction was performed at least 20 minutes after the instillation of drops. No less than
five readings were taken from which the representative valueas determined by the instrument
was used for further analysis. The representative value is widely used as an output value for this
instrument and has recently been shown to be comparable to other methods of averaging
refractive error.[16] Data collection occurred at the childs school (67 year olds: primary
school; 1213 year olds: post-primary school) during the school day. After examination of the
child, parents/guardians were asked to complete a questionnaire to determine the childs birth
history, family history and lifestyle. The study was approved by the University of Ulsters
Research Ethics committee and adhered to the tenets of the Declaration of Helsinki. Written
informed consent was obtained from parents or guardians and verbal or written assent was
obtained from participants on the day of the examination.
Within Phase 1 of the study, baseline data were collected from 399 6 to 7 year old children
(younger cohort) and 669 12 to 13 year old children (older cohort). Phase 2 of the NICER
study, collected follow-up data on the participants three years later, these data are presented
elsewhere.[11] Phase 3 of the NICER study collected follow-up data on the same participants
six years after their initial participation, 20122014. For the younger cohort, the majority of
data collection at Phase 3 occurred at the childs post-primary school (n = 200, 93%) and for
some children where it was not possible to carry out testing at their post-primary school, data
collection occurred at a University of Ulster campus (n = 15, 7%). For participants within the
older cohort, data collection took place at one of the University of Ulster campuses or at a data
collection site close to the participants home address (e.g. local church hall).
Data collection protocols were the same at all phases of the study. Cycloplegic autorefraction
was measured using the latest version of the binocular open-field autorefractor at Phase 3
(NVision-K 5001, Shin-Nippon, Tokyo, Japan). This instrument has been shown to be accurate
and repeatable over a wide range of refractive errors.[17,18]
Refractive Classifications
The representative value was used to calculate spherical equivalent refraction (SER) using sphere
+ cylinder/2. There was a strong correlation between SER data from right and left eyes (Spear-
mansrho,allp<0.001) therefore only data from right eyes are presented. SER was used to
group participants into the following refractive classifications: a participant was classified as a
myope if SER was -0.50 dioptre (D) or less; an emmetrope if SER was greater than -0.50D but
less than +2.00D; and a hyperope if SER was +2.00D or greater. These classifications are similar
to those used previously to define refractive error by the NICER study, [11,19] by the Refractive
Error in School Children Study (RESC), [12,20] the Sydney Myopia Study (SMS)[13] and the
Sydney Adolescent and Vascular Eye Study (SAVES).[4] Raw data from Sorsby et al.[14] were
obtained and analysed using the same refractive criteria as the current study to aid comparison.
Statistical Analysis
Data were analysed using Intercooled Stata 10.1 software (StataCorp LP, Texas, USA). Non-
participants are defined as individuals who participated in Phase 1 of the study but did not par-
ticipate in Phase 3. Differences between participants and non-participants for both cohorts
were investigated using Mann-Whitney analysis (SER & socioeconomic rank), student t-tests
Six Year Refractive Change in the UK - The NICER Study
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(age) and chi-squared analysis (gender, refraction classification, spectacle wear at Phase 1,
parental education & parental myopia). Socio-economic rank was determined using a Geo-
graphical Information Systems (GIS) approach. Unit postcode address information and the
Northern Ireland multiple deprivation measure were applied to assign an area-based rank mea-
sure of economic deprivation to each child. The measure, calculated at the small scale census
Output Area (OA) level, is based on three weighted domains of deprivation: income (41.7%),
employment (41.7%) and proximity to services (16.6%). Level of parental education and paren-
tal myopia were established through parent/guardian questionnaire based survey at Phase 1.
For parental education, participants were dichotomised as having at least one parent with third
level education (college or university degree) or neither parent had third level education and
for parental myopia, participants were dichotomised as having at least one myopic parent or
having no myopic parents.
Cross-sectional distribution of refractive errors are presented for Phase 1 and Phase 3.
Cumulative incidence of myopia was calculated as the number of individuals who were classi-
fied as myopic at Phase 3 but were not classified as myopic at Phase 1. Cumulative reduction in
hyperopia (+2.00DS) was also assessed and is reported as the number of individuals classified
as hyperopic at Phase 1 but not classified as hyperopic by Phase 3. Annual incidence of myopia
(or reduction of hyperopia) were calculated by dividing the cumulative incidence (or reduc-
tion) by the mean follow-up interval (years) for each cohort as a whole. Six-year cumulative
change in SER was calculated as measurement at Phase 3”–“measurement at Phase 1. Esti-
mated annual change in SER was calculated by dividing the change from Phase 1 to Phase 3 by
the time interval between examinations for each individual. The Shapiro-Wilk test was used to
determine normality of the data. Mann-Whitney and Kruskal-Wallis tests or their parametric
equivalents (Student t-test or analysis of variance) where appropriate, were used to analyse dif-
ferences between cohorts and refractive error groups. Mixed effect logistic regression analyses
and two sample tests of proportion were used to compare distribution differences within the
NICER study and between the NICER study data and that of Sorsby et al.[14] and French et al.
[4]. Chi-squared analyses were used for categorical and percentage comparisons. A pvalue of
less than 0.05 was considered statistically significant.
Results
Participants
All participants who took part in Phase 1 were eligible to participate in Phase 3 irrespective of
their participation in Phase 2. We were unable to contact a number of participants at Phase 3
in both the younger (n = 25, 6.0%) and older cohorts (n = 8, 1.2%). From Phase 1, overall par-
ticipation in Phase 3 was 54% and 34% for the younger and older cohorts respectively. The
majority of participants at Phase 3 were white (99%), reflective of the Northern Irish popula-
tion, [21] therefore data are reported for white participants only. One participant in the older
cohort was also excluded from data analysis due to emergent ocular pathology (keratoconus).
Data are presented for 212 participants within the younger cohort (50% male) and for 226 par-
ticipants within the older cohort (43% male). Fig 1 describes the number of participants con-
tacted, recruited and examined at Phase 3.
Younger Cohort. The mean age of the younger cohort at Phase 3 was 13.1±0.4 years
(range 12.4 to 13.9 years). There was no statistically significant difference between participants
and non-participants at Phase 3 in terms of age (t = 1.39, p= 0.17), gender (Χ
2
= 0.0014,
p= 0.97), refractive error (SER [z = -0.18, p= 0.86] or refractive classification [Χ
2
= 0.95,
p= 0.81]), spectacle wearers vs non-spectacle wearers (Χ
2
= 0.41, p= 0.52) and socio-economic
indicators (socio-economic rank [z = -1.46, p= 0.14], and parental education [Χ
2
= 0.05,
Six Year Refractive Change in the UK - The NICER Study
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p= 0.83]). Those who had at least one myopic parent were more likely to participate at Phase 3
compared to those with no myopic parents (Χ
2
= 10.51, p= 0.001).
Older Cohort. The mean age of the older cohort at Phase 3 was 19.2±0.5 years (range 18.0
to 20.2 years). Females within the older cohort were statistically more likely to participate than
males (Χ
2
= 7.82, p= 0.005). There was no statistically significant difference in age (t = -1.90,
Fig 1. Flow diagram describing participant contactability, recruitment and exclusion from Phase 1 to
Phase 3.
doi:10.1371/journal.pone.0146332.g001
Six Year Refractive Change in the UK - The NICER Study
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p= 0.06), refractive error (SER [z = -0.40, p= 0.69] or refractive classification [Χ
2
= 5.60,
p= 0.13]), socio-economic indicators (socio-economic rank [z = -1.72, p= 0.09], parental edu-
cation [Χ
2
= 0.12, p= 0.73]) or parental myopia (Χ
2
= 1.02, p= 0.31) between participants and
non-participants at Phase 3. Spectacle wearers in the older cohort were statistically significantly
more likely to participate at Phase 3 compared to non-spectacle wearers (Χ
2
= 5.45, p= 0.02)
however the range of spherical error of those who were spectacle wearers was wide (-7.00D to
+9.00D).
Follow-up Interval
The majority of follow-up examinations at Phase 3 occurred within 72 ±3 months of the initial
participation in Phase 1 (younger 92.5%; older 73.9%). There was no statistically significant dif-
ference between cohorts with regard to the time interval between Phase 1 and 3 examinations
(Mann-Whitney z = 0.71, p= 0.48) (younger median 73.2 months, IQR 70.3 to 73.9 months,
range 68.8 to 76.7 months; older median 72.5 months, IQR 69.7 to 74.1 months, range 67.7 to
81.8 months).
Incidence of Myopia and Reduction in Hyperopia between Phase 1 and
Phase 3
Tables 1and 2describe the changing distribution of myopia and hyperopia for the younger
and older cohorts. SER at Phase 1 and 3 are also plotted (Fig 2A & 2B) to show the number of
new myopes by Phase 3 and the refractive classification in which they were originally grouped
at Phase 1. The number of participants with reducing hyperopia are also highlighted.
For those participants within the younger cohort classified as myopic at Phase 3 the cumula-
tive median change in SER was -1.38D (IQR -0.63 to -2.75D) over the six-year period. Esti-
mated annual median change for this group of participants was -0.23D (IQR -0.11 to -0.45D)
with the largest estimated annual change for one individual of -0.51D. For the older cohort,
those classified as myopic at Phase 3 showed a cumulative median change of -0.63D (IQR -0.13
to -1.00D) over the six-year period. Estimated annual median change for these participants was
-0.10D (IQR -0.02 to -0.17D) with the largest estimated annual change of -0.51D. There was no
statistically significant difference between genders for the annual rate of change in SER for
Table 1. Proportion of myopes and incidence of myopia between Phase 1 and 3.
Cohort Proportion of Myopes
Phase 1 (%)
Proportion of Myopes
Phase 3 (%)
pCumulative
Incidence (%)
pEstimated Annual
Incidence (%)
Younger
All (n = 212) 1.9 (n = 4) 14.6 (n = 31) <0.001 13.0 - 2.2
Males
(n = 105)
1.0 (n = 1) 14.3 (n = 15) 0.006 13.5 Reference 2.3
Females
(n = 107)
2.8 (n = 3) 15.0 (n = 16) 0.005 12.5 0.63 2.1
Older
All (n = 226) 16.4 (n = 37) 18.6 (n = 42) 0.51 4.2 - 0.7
Males (n = 98) 15.5 (n = 16) 16.5 (n = 17) 0.84 2.4 Reference 0.4
Females
(n = 128)
17.1 (n = 21) 20.2 (n = 25) 0.49 5.6 0.38 0.9
Summary of the proportion of myopes at Phase 1 and 3 and the incidence of new myopes between Phase 1 and Phase 3 for the younger and older
cohorts, stratied by gender. n = number of participants
doi:10.1371/journal.pone.0146332.t001
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those classified as myopic by Phase 3 for either the younger (Mann-Whitney, z = 0.41,
p= 0.68) or older cohorts (Mann-Whitney, z = -1.26, p= 0.21).
There was no statistically significant difference between the cross-sectional proportion of
participants aged 1213 years classified as myopic at baseline (20062008, 16.4%) and those
classified as myopic at Phase 3 (20122014, 14.6%) (Two-sample test of proportion z = -0.51,
p= 0.62). Participants in both cohorts who were classified as myopic at 1213 years of age had
similar levels of myopia (median = -1.25DS, IQR -0.81 to -1.69DS in 20062008; median =
-1.25D, IQR -0.88 to -2.38DS in 20122014) (Mann-Whitney, z = -0.85, p= 0.40).
There was a significant decline in the proportion of hyperopes in the younger cohort
between age 67 years (21.7%) and 1213 years (14.2%) (z = -2.05, p= 0.04). Children who
were hyperopic at 67 years and remained hyperopic at 1213 years had a significantly more
positive SER at 67 years (median +3.69DS) compared to those who lost their hyperopia
(median +2.19DS at 67 years) (Mann-Whitney, z = 4.62, p<0.001). The proportion of hype-
ropes within the older cohort remained relatively stable between 1213 years (15.0%) and 18
20 years (17.7%) and there were few participants who lost their hyperopia over the six-year
period (n = 4). Similar to the younger cohort, participants who were classed as hyperopic aged
1213 years and remained hyperopic at age 1820 years had a significantly greater SER at 12
13 years of age (median +4.13DS) compared to those who lost their hyperopia (median
+2.07DS at 1213 years) (Mann-Whitney, z = 2.84, p= 0.005). Hyperopic participants showed
on average an annual change in SER of -0.09DS (IQR -0.17 to -0.02DS) and +0.02DS (IQR
-0.04 to 0.11DS) for the younger and older cohorts respectively.
Proportion, Incidence and Progression of Myopia among the NICER
Study participants compared with a contemporary Sydney population
and a historical UK based population
Proportion of Myopia. Data from the current study are compared with data from the
recent report from French et al.[4] (Sydney Myopia Study [SMS] and Sydney Adolescent Vas-
cular and Eye Study [SAVES]) who present the prevalence, incidence and progression of myo-
pia in two similar age cohorts of Australian European Caucasian children (aged 6 years and 12
years at baseline) and longitudinal follow-up after 56 years during a similar time period as the
present study (2004 to 2011). These data are presented in Fig 3.
Table 2. Proportion of hyperopes and decline of hyperopia between Phase 1 and 3.
Cohort Proportion of Hyperopes
Phase 1 (%)
Proportion of Hyperopes
Phase 3 (%)
pCumulative
Reduction (%)
pEstimated Annual
Reduction(%)
Younger
All (n = 212) 21.7 (n = 46) 14.2 (n = 30) 0.04 43.5 - 7.3
Males
(n = 105)
21.0 (n = 22) 13.3 (n = 14) 0.14 50.0 Reference 8.3
Females
(n = 107)
22.4 (n = 24) 15.0 (n = 16) 0.15 37.5 0.97 6.3
Older
All (n = 226) 15.0 (n = 34) 17.7 (n = 40) 0.44 11.8 - 2.0
Males (n = 98) 17.4 (n = 17) 19.4 (n = 19) 0.71 5.9 Reference 1.0
Females
(n = 128)
13.3 (n = 17) 16.4 (n = 21) 0.48 17.6 0.39 2.9
Summary of the proportion of hyperopes at Phase 1 and 3 and the decline of hyperopia between Phase 1 and Phase 3 for the younger and older cohorts,
stratied by gender. n = number of participants.
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Fig 2. Scatterplots of SER at Phase 1 versus SER at Phase 3 for the younger and older cohorts
respectively. Data are grouped into refractive classifications as illustrated in the key. The gray boxes
indicate participants who became myopic (younger cohort n = 27; older cohort n = 8) or lost their hyperopia
(younger cohort n = 20; older cohort n = 4) between Phase 1 and 3. The dashed lines represent the myopia
cut-off point of -0.50D or less and the dotted line represents the hyperopia cut-off of +2.00D or greater. The
solid black line represents unity- those falling below the line are showing a myopic change in SER.
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Data from the current study are also compared with historical UK data from Sorsby et al.
[14](Fig 4). Sorsby et al. present data for two age groups; children who were between three and
ten years of age at baseline (younger cohort) and children who were ten to 15 years of age at
baseline (older cohort). Longitudinal data are also presented with a mean follow-up examina-
tion occurring at 3.1±0.9 years (range 2.2 to 5.3 years) and 3.7±0.9 years (range 2.0 to 5.3
years) for their younger and older cohorts respectively.
In contrast to contemporary literature, and to the data presented in Fig 4, Sorsby et al.[14]
applied an SER of less than zero dioptres to define myopia in his published report. Using this
criterion and applying it to the NICER study data, 23% of children aged 1213 years in the
NICER study were classified as myopic at Phase1 (20062008) compared to 10% reported by
Sorsby et al. in the 1960s for their older cohort of children aged between 1016 years. These
data and those in Fig 5 indicate a two-fold increase in the proportion of myopia in the UK over
the last five decades in children aged between 10 and 16 years (Two sample test of proportion
z = 3.12, p= 0.002).
Fig 5 presents the distribution of SER for 67 year old children within Phase 1 of the NICER
study (20062008) and from Sorsbys report.[14] The median SER for Sorsbys67 year olds in
the 1950s-1960s was +1.80DS (IQR +1.30 to +2.70DS) which is significantly more hyperopic
than the median SER (+1.13DS, IQR +0.63 to +1.75DS) for the 67 year olds in the NICER
study in 20062008 (Mann-Whitney z = 7.15, p<0.001).
Fig 3. Comparison of refractive error prevalence in the UK (NICER Study) to Australia (SMS/SAVES) at baseline and 56 year follow-up. The
brackets show the statistical comparisons of the proportions of myopes between the two studies; black indicates statistically significant difference, gray
indicates no statistically significant difference (Two sample test of proportion).
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Table 3 describes the mean annual change in SER for those classified as myopic at baseline
and the estimated annual incidence of myopia for the NICER and Sydney data. The Sydney
study [4] reported no statistically significant difference in the annual progression rate between
children of European Caucasian or East Asian ethnicity when myopia was present at baseline,
therefore change in SER data for all ethnicities in the Sydney study are used for comparison.
Isolated European Caucasian data are not available for the Sydney data for this metric.
Discussion
The present study reports the six-year change in refractive error status including the incidence
of myopia and reduction of hyperopia, within a white, UK based population of children and
young adults. In the present study, the proportion of participants defined as myopic is similar
to previous reports of European Caucasian children of similar age.[4,10,22,23] However it is
relatively low in comparison to reports among children of Asian background whether living in
Asia or elsewhere.[1,4,6,8,20,23] French et al.[4] report a significant increase in the prevalence
of myopia in Australian Caucasian children between 2004 and 2011 and infer that the preva-
lence of myopia is increasing in Australia, similar to reports in many other parts of the world.
[13] The results from the present study demonstrate a two-fold increase over 50 years in the
proportion of teenagers who are myopic in the UK, but no significant short-term increases in
myopia prevalence during the past decade in our population.
Fig 4. Comparison of UK refractive error distribution between 1950s-1960s (Sorsby study) and 20062014 (NICER study) at baseline and follow-
up. The brackets indicate the statistical comparisons of the proportions of myopes between the two studies; black indicates statistically significant difference,
gray indicates no statistically significant difference (Two sample test of proportion).
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Fig 5. Distribution of spherical equivalent refractive errors in 67 year old children within the NICER study Phase 1 (20062008) and 67 year old
children from Sorsby et al.[14]. Data points represent a one dioptre interval (for example, the % of participants represented at point 0 on the x-axis have an
SER of less than or equal to 0DS but greater than -1 DS. Data points at the extremes of the x-axis represent participants with SER of greater than or equal to
+5DS or less than or equal to -5DS.
doi:10.1371/journal.pone.0146332.g005
Table 3. Comparison of the incidence and progression of myopia between the NICER and Sydney studies for the younger and older cohorts.
YOUNGER COHORT OLDER COHORT
Current Study NICER Age range 67to1213 years 1213 to 1820 years
Estimated Annual Incidence of myopia 2.2%*0.7%*
Mean Annual Change in SER for participants classed as
myopic at Phase 1 (D) (Range)
n = 4; -0.18; (-0.47 to
-0.02)
n = 37; -0.09; (-0.51 to
+0.19)
Sydney, Australia
French et al.[4]
Age Range 67to1213 years 1213 to 17 years
Estimated Annual Incidence of myopia 1.3%*2.9%*
Mean Annual Change in SER for participants classed as
myopic at Phase 1 (D)
n = 11; -0.41; (range not
available)
n = 128; -0.31; (range not
available)
n = number of participants.
*= statistically signicant difference in annual incidence between younger and older cohorts within the same study (Χ
2
,p<0.05).
= statistically signicant difference in annual incidence between the NICER study and the Sydney data (within the same age cohort) (Χ
2
,p<0.05).
doi:10.1371/journal.pone.0146332.t003
Six Year Refractive Change in the UK - The NICER Study
PLOS ONE | DOI:10.1371/journal.pone.0146332 January 19, 2016 11 / 19
Proportion and Onset of Myopia
There was a statistically significant increase in the number of myopes between 67 and 1213
years. The estimated annual incidence in myopia within this younger cohort (2.2%) did not dif-
fer significantly from that found in European Caucasian children in Sydney (1.3%) and is com-
parable with annual incidences reported in the ethnically diverse populations described in the
full Sydney data set (2.2%) (French et al.[4]-including all ethnicities) and in the Collaborative
Longitudinal Evaluation of Ethnicity in Refractive Error (CLEERE) study. The latter reports an
annual incidence of myopia of 2.8% for children in the United States aged six years at baseline
who were reviewed annually for seven years.[24] In general, children living within the UK, US
and Australia appear to have similar low annual incidences of myopia, regardless of ethnicity,
compared to the high annual incidences reported for children living in East Asia. Saw et al.[8]
report an annual incidence of myopia of 15.9% among Singaporean children aged seven years
at baseline (reviewed after three years) and Fan et al.[6] report on average a 14.4% annual inci-
dence of myopia among children from Hong Kong (aged between 711 years at baseline,
reviewed after one year). Prospective data from ethnically diverse groups living in the UK
would be beneficial to identify how ethnicity and environment interact in the UK.
Gender did not significantly impact on myopia incidence in the NICER study in either age
cohort. Although the proportion of myopes who were females was higher than males in both
cohorts, this did not reach statistical significance. Zhao et al.[20] in the Refractive Error of
School-Children (RESC) study in the Shunyi District, China, report an annual incidence of
myopia of 2.2% among children who were five years old at baseline (followed up after 28.5
months), similar to our younger cohort. However among children who were 12 years at baseline
in Zhao et al.s study, the annual incidence of myopia had risen to 10.7% for males and 16.7%
for females in stark contrast to the present study. French et al.[4] also report significantly greater
myopia incidence in females in their older group of children (aged 1213 years at baseline) but
no significant difference between genders for their younger cohort (aged 67 years at baseline).
Saw et al.[8] also report a higher annual incidence of myopia in female Singaporean children
(15.2%) (aged 79 years at initial visit, reviewed after three years) compared to males (13.2%)
however similar to the NICER study, this difference did not reach statistical significance.
Within the present study there was no statistically significant increase in the proportion of
participants classed as myopic between 1213 years and 1820 years of age. The cumulative
incidence of myopia for this cohort was 4.2% with an estimated annual incidence of 0.7%. By
contrast, the younger cohort demonstrated a greater cumulative incidence of myopia in the
six-year sampling period (13% vs 4.2%) revealing that children were three times more likely to
become myopic between 67 and 1213 years than between 1213 and 1820 years in our pop-
ulation. Compared to Sorsby et al.[14](Fig 5) our results show that children are becoming
myopic at a younger age in present day UK compared to 50 years ago. Children within the
NICER study also demonstrated a significantly less hyperopic SER at 67 years of age com-
pared to those of corresponding age within Sorsbys study. Williams et al.[25] have recently
reported a similar trend of increasing myopia prevalence in adults in Northern and Western
Europe where the prevalence of myopia was almost twice as high in young adults aged 2529
years (47.2%) compared to those of middle age (27.5%, aged between 5059 years). They also
report a significantly higher prevalence of age-standardised myopia among adults born
between 19401979 (23.5%) compared to those born between 19101939 (17.8%).
Cumulative incidence of myopia decreased with increasing age from the younger to the
older NICER cohort. This contrasts strongly with data in a sample of Chinese children (aged
515 years at baseline, reviewed after 28.5 months) for which Zhao et al.[20] report a 27%
increase in cumulative risk of myopia with each additional year of age. French et al.[4] also
Six Year Refractive Change in the UK - The NICER Study
PLOS ONE | DOI:10.1371/journal.pone.0146332 January 19, 2016 12 / 19
report that the incidence of myopia increased with increasing age among their Australian chil-
dren, describing the annual incidence of myopia in their older cohort (aged 12 years at base-
line) as 2.9% compared with 1.3% in their younger cohort (aged six years at baseline) with an
annual incidence of 1.3%. Inspection of Fig 3 suggests that although the prevalence of myopia
among younger Australian children is lower than that found in our UK population, by age 17
years the proportion of myopes in the two studies nears equivalence. It is also seen in Fig 3 and
reported by French et al.[4] that cross-sectional data indicate a shift towards earlier onset myo-
pia in Australia in a relatively short space of time; the prevalence of myopia in 1213 year old
children tested in 20042005 is reported as 4.4% compared with 8.6% in 20092011. This shift
has been attributed to a change in lifestyle amongst younger Australian children; including
increased use of computers and hand-held technology and less time spent playing outside.
Spending time outdoors has been postulated to protect against the onset and progression of
myopia [2629] and French et al.[28] suggests that while young children may have tradition-
ally been protected by the sunny climate and outdoor lifestyle prevalent in Australia, modern
lifestyle pressures mean that time outdoors is sacrificed to the growing demands of study and
the attraction of computer games and tablets, and hence susceptibility to myopia is intensified.
The data from the present study do not support a rapid change in the timing of myopia onset
in the UK as reported in Australia, but do reveal that myopia occurs at a younger age in the UK
in the 21
st
century than reported in the 1960s. This, in addition to the evidence of a twofold
increase in the number of myopes, is likely to reflect the significant changes in lifestyle and
environment that have occurred over the last 50 years in the UK (e.g. time spent indoors, use
of electronic devices, change in diet, obesity, onset of puberty, sedentary lifestyles).
Rate of Change
The annual rate of change of SER for those classified as myopic at Phase 1 was greater at 67
years than at 1213 years similar to trends reported in other white [4,14] and Asian childhood
populations.[8] The annual rate of change for those classified as myopic at baseline is much
greater in the Sydney study (Table 3) across both the younger and older cohorts than for the
NICER study participants. In the younger cohort of the NICER study the annual rate of change
of SER from 67to1213 years for those who were classified as myopic by Phase 3 (n = 31)
also shows myopic progression occurring at a slower rate than their Australian contemporaries.
Pärssinen and Lyyra [30] report an average annual change of -0.55D among myopic Finnish
children who were approximately 10 years old at baseline and were reviewed every year for
three years, and report that females progressed significantly faster than males. This annual rate
of progression is over twice that of the younger cohort of the present study and in contrast to
Pärssinen and Lyyra we found no significant difference in the incidence or progression of myo-
pia between genders. The average annual change in SER for participants who were classified as
myopic at Phase 3 was -0.23D and -0.10D for the younger and older cohorts respectively. Con-
sidering a clinically significant change in SER to be -0.25D or more, our data suggest that to
ensure children have appropriate, up-to-date refractive correction the following guidance
could be applied: those children aged 67 years who are myopic or at risk of developing myopia
(e.g. those with a positive family history, those who are emmetropic or have low levels or
hyperopia (<+0.75D) in early childhood, those with sedentary lifestyles, those spending less
than three hours outdoors per day-[3136]) should be advised to have an annual eye examina-
tion. At 1213 years, myopic children or for those at risk of developing myopia (as above for
67 years and in addition those in academically selected schooling [35]) it may be appropriate
to extend this routine sight test interval to two years unless symptoms indicate a need for more
rapid intervention. This guidance relates only to monocular spherical equivalent refractive
Six Year Refractive Change in the UK - The NICER Study
PLOS ONE | DOI:10.1371/journal.pone.0146332 January 19, 2016 13 / 19
error and does not consider the dynamics of other visually important refractive features such
as astigmatism and anisometropia. Clinicians should be aware that these data apply to a UK
based population where myopia progression appears slower than that of other populations.
Change in Hyperopia
The proportion of participants classified as hyperopic within the present study was high for both
cohorts in comparison to the Sydney population [4] but comparable to that recorded under
cycloplegia by Logan et al.[23] for white UK children of the same age. Czepita et al.[22]reporta
higher prevalence of hyperopia (30.8%) in Polish children aged 1014 years living in rural areas
compared to urban areas (7.1%) in Poland. Northern Ireland has a relatively rural population
(population density of 2501000 per km
2
)[37] which is similar to that of rural Poland (popula-
tion density of <1000 per km
2
)[38] and in contrast to the urban population of Sydney (7000-
8000/km
2
).[39]However,Loganet al.s data represent children schooled in a large UK city and
present a relatively similar situation to that found in Northern Ireland. Further work is needed to
fully understand why hyperopia is more common in some populations than in others.
The present study reports a significant annual reduction in hyperopia of 7.3% within the
younger cohort as they progress from 67to1213 years of age. There are few studies which
have prospectively investigated change in hyperopia, however French et al.[4] report a greater
annual rate of reduction in hyperopia over a 56 year time period in both their cohorts of Austra-
lian children living in Sydney (aged six and 12 years at baseline) compared to the present study;
with an annual reduction of hyperopia of 12.3% and 10.2% for the younger and older cohorts
respectively. French et al.s data are from children of mixed ethnicity (22% East Asian) which
may explain the greater myopic shift in refractive error compared to the present study. Zhao
et al.[20] also report a large annual reduction of hyperopia of 17.6% among children within the
Shunyi District of China (aged 515 years at baseline). Baseline prevalence of hyperopia within
Zhaos Chinese population was also much lower (3%) than that found in the NICER study.
For both cohorts within the present study, those whose hyperopia was greater than +3.50DS
showed a relatively stable SER over the six-year period, in contrast to less hyperopic peers
whose hyperopia tended to reduce towards emmetropia during the study. Prospective studies
of infantsand young childrens refractive development also demonstrate that hyperopia that
fails to resolve through emmetropisation within the first year or two of life is likely to be persis-
tent.[4042] Mutti et al.[43] states that infants with hyperopic errors of 4D or more are signifi-
cantly less likely to emmetropise than infants with lower levels of hyperopia and that
hyperopia of this level or greater is persistent. We have demonstrated that this persistent infan-
tile hyperopia endures through later childhood and early adulthood. Several researchers have
identified an association between retention of significant hyperopia in infancy (4D or more)
and poor accommodative function [4447]. When retained beyond infancy higher levels of
hyperopia signal a resistance of the visual system to modification through visual feedback usu-
ally associated with emmetropisation. Kulp et al.[48] have suggested that the presence of het-
erotropia may reduce the rate of hyperopic decline and within our study, one third of those
with persistent hyperopia demonstrated heterotropia. In contrast to studies exploring hyper-
opic decline in childhood in other geographic and ethnic populations [4,49], the current study
reports a greater proportion of significant hyperopia throughout childhood and early adult-
hood and a much lower annual rate of refractive change in hyperopia. It appears that genetic or
environmental variance influences the persistency of hyperopia. Our data would support
Mezer et al.s[49] findings that children with mild hyperopia may be able to cease spectacle
wear in later childhood, however those with moderate to high hyperopia will need to retain
their refractive correction.
Six Year Refractive Change in the UK - The NICER Study
PLOS ONE | DOI:10.1371/journal.pone.0146332 January 19, 2016 14 / 19
Strengths and Limitations
Study methods and refractive classifications used in the NICER study were similar to other
large studies of refractive error in children for ease of comparison.[4,12,23] The epidemiologi-
cal design of the initial NICER study did not give consideration to sample size for future pro-
spective studies, therefore sample sizes at six year follow-up while favourable in comparison to
the only other published UK based prospective study evaluating cycloplegic refractive data in
childhood, [14] are modest in comparison to other published data.[4,20,31] While most partic-
ipants in the present study were contactable at Phase 3 and participation rates are comparable
to other longitudinal studies over similar time frames, [4,31] a significant number of partici-
pants were not re-examined particularly within the older cohort. Within the younger cohort,
there were no differences between those who participated at Phase 3 and those lost to follow-
up in age, gender, refractive error and socioeconomic factors. Children who had at least one
myopic parent were more likely to participate at Phase 3 than those with no myopic parents
which may have a genetic influence on the incidence of myopia within the younger cohort.
Within the older cohort, females were significantly more likely to participate than males.
We also report a higher percentage of myopic females than males and a greater incidence of
myopia in females to males within this cohort; however the differences were not statistically
significant. These retention issues could potentially bias our data towards more myopia in the
older cohort. Within the older cohort, spectacle wearers were more likely to participate at
Phase 3 than non-spectacle wearers possibly due to a greater interest in their eye care, however
spectacles wearers included both hyperopes and myopes.
The NICER study data have been compared with the data from Sorsby et al.[14] and
although efforts have been made to compare refractive classifications and rate of change of
myopia, there are limitations in these comparisons due to differences in the exact age of the
cohorts compared, the informal sampling methodology, method of refraction and lack of uni-
formity in the follow-up intervals in Sorsbys study. Data from 67 year old children from the
Sorsby study have been directly compared with 67 year old children from the NICER study
due to a large number of data points within the Sorsby study at this age; participant numbers in
the Sorsby study were limited in other comparable age groups to the NICER study and have
not been directly compared. Given that Sorsbys work is widely cited and well known in the
UK and beyond, it is useful to examine it in light of the contemporary findings of the NICER
study in an attempt to explore how refractive error has altered over the 50 year period.
The data presented on change in refractive error within this study are supported by ocular
biometric data that are presented in Supporting Information (S1,S2,S3 and S4 Tables).
Conclusions
In comparison to other worldwide studies the proportion of children and young adults classi-
fied as myopic remains relatively low in this white, UK based population and the proportion of
myopes is similar to other populations of European Caucasians of similar age. Differences
between the proportion of myopes in the NICER study and a comparable study of Australian
children of European Caucasian ethnicity apparent at 1213 years were eliminated by 17 years
of age. Our data suggest that the proportion of myopes has remained relatively stable in the UK
over the short-term but has doubled in the last 50 years. Our results also suggest white children
in the UK are becoming myopic at a younger age than previously demonstrated; children are
more likely to develop myopia in the UK between 67 and 1213 years than during teenage
years. Hyperopic errors above +3.50D tend to be persistent and stable across the school years,
but lower levels of hyperopia often decrease.
Six Year Refractive Change in the UK - The NICER Study
PLOS ONE | DOI:10.1371/journal.pone.0146332 January 19, 2016 15 / 19
Supporting Information
S1 Table. Raw data set for the change in ocular biometrics (AL = axial length, corneal
power & ACD = anterior chamber depth) and SER (spherical equivalent refraction)
between Phase 1 and Phase 3 (67 years to 1213 years) for participants classified as myo-
pic within the younger cohort. Participants shown in bold were classified as myopic at both
Phase 1 and Phase 3. Outlined below are the Spearman correlations between the change in SER
and change in AL, corneal power and ACD. Change in SER vs Change in AL, Spearmans Cor-
relation, ρ= -0.7510, p<0.001. Change in SER vs Change in Corneal Power, Spearmans Corre-
lation, ρ= -0.036, p= 0.985. Change SER vs Change in ACD, Spearmans Correlation, ρ=
-0.347, p= 0.061.
(PDF)
S2 Table. Raw data set for the change in ocular biometrics (AL = axial length, corneal
power & ACD = anterior chamber depth) and SER (spherical equivalent refraction)
between Phase 1 and Phase 3 (1213 years to 1820 years) for participants classified as
myopic within the older cohort. Participants shown in bold were classified as myopic at both
Phase 1 and Phase 3 and participants shown in italics were classified as myopic at Phase 1 but
not at Phase 3. Outlined below are the Spearman correlations between the change in SER and
change in AL, corneal power and ACD. Change in SER vs Change in AL, Spearmans Correla-
tion, ρ= -0.740, p<0.001. Change in SER vs Change in Corneal Power, Spearmans Correla-
tion, ρ= 0.045, p= 0.768. Change SER vs Change in ACD, Spearmans Correlation, ρ= -0.302,
p= 0.0047.
(PDF)
S3 Table. Raw data set for the change in ocular biometrics (AL = axial length, corneal
power & ACD = anterior chamber depth) and SER (spherical equivalent refraction)
between Phase 1 and Phase 3 (67 years to 1213 years) for participants classified as hyper-
opic at Phase 1 within the younger cohort. Outlined below are the Spearman correlations
between the change in SER and change in AL, corneal power and ACD. Change in SER vs
Change in AL, Spearmans Correlation, ρ= -0.707, p<0.001. Change in SER vs Change in Cor-
neal Power, Spearmans Correlation, ρ= -0.114, p= 0.457. Change SER vs Change in ACD,
Spearmans Correlation, ρ= -0.520, p<0.001.
(PDF)
S4 Table. Raw data set for the change in ocular biometrics (AL = axial length, corneal
power & ACD = anterior chamber depth) and SER (spherical equivalent refraction)
between Phase 1 and Phase 3 (1213 years to 1820 years) for participants classified as
hyperopic at Phase 1 within the older cohort. Outlined below are the Spearman correlations
between the change in SER and change in AL, corneal power and ACD. Change in SER vs
Change in AL, Spearmans Correlation, ρ= -0.594, p<0.001. Change in SER vs Change in Cor-
neal Power, Spearmans Correlation, ρ= 0.008, p= 0.964. Change SER vs Change in ACD,
Spearmans Correlation, ρ= -0.322, p= 0.063.
(PDF)
Acknowledgments
The authors thank the College of Optometrists (London, UK) for their ongoing support for the
NICER study, and the participants in the NICER study for their ongoing commitment to this
research and to the schools where the research is conducted.
Six Year Refractive Change in the UK - The NICER Study
PLOS ONE | DOI:10.1371/journal.pone.0146332 January 19, 2016 16 / 19
Author Contributions
Conceived and designed the experiments: KJS LOD. Performed the experiments: SJM KJS
LOD. Analyzed the data: SJM KJS LOD. Contributed reagents/materials/analysis tools: SJM
KJS LOD. Wrote the paper: SJM KJS LOD.
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... An increasing number of systematic reviews, meta-analyses and international recommendations intend to bridge the gap to clinical practice, 1,10,11 but areas of uncertainty remain, and differing recommendations, which often cannot be implemented at a local level, may create confusion. 12 Given the increasing prevalence of myopia in CYP in the UK over the past 50 years (the current prevalence is 14.6% and 16.4% of 12-13 and 17-year-olds, respectively) 13 and with 25%-30% of young adults now affected across Western Europe, 14 myopia-related complications are an increasing public health concern. Over the past 10 years, the number of retinal detachment repair operations has increased in England and Scotland. ...
... (b) Removal of these highlights 'progression, axial length, interventions, practitioners/children/ patients, risk and evidence' as prominent areas. definition of high myopia as alternative in specific contexts (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15). Several of the proposed statements relating to META-PM definitions generated a high rate of 'don't know/ don't want to answer' responses ( ...
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Introduction This work aimed to establish the largest UK and Ireland consensus on myopia management in children and young people (CYP). Methods A modified Delphi consensus was conducted with a panel of 34 optometrists and ophthalmologists with expertise in myopia management. Results Two rounds of voting took place and 131 statements were agreed, including that interventions should be discussed with parents/carers of all CYP who develop myopia before the age of 13 years, a recommendation for interventions to be publicly funded for those at risk of fast progression and high myopia, that intervention selection should take into account the CYP's hobbies and lifestyle and that additional training for eye care professionals should be available from non‐commercial sources. Topics for which published evidence is limited or lacking were areas of weaker or no consensus. Modern myopia management contact and spectacles are suitable first‐line treatments. The role and provision of low‐concentration atropine needs to be reviewed once marketing authorisations and funding decisions are in place. There is some evidence that a combination of low‐concentration atropine with an optical intervention can have an additive effect; further research is needed. Once an intervention is started, best practice is to monitor non‐cycloplegic axial length 6 monthly. Conclusion Research is needed to identify those at risk of progression, the long‐term effectiveness of individual and combined interventions, and when to discontinue treatment when myopia has stabilised. As further evidence continues to emerge, this consensus work will be repeated to ensure it remains relevant.
... 5 Further, it has also been estimated and proposed that by 2050, 10 % of myopes will be high myopes, 5 and therefore will suffer from the additional ocular changes and abnormalities that high myopia implies. 7 In Europe, the current prevalence of myopia is variable across countries (ranging from 15 % to almost 50 %) [8][9][10][11] and these discrepancies could arise from differences in participant recruitment and study design, but could also arise from genetic as well as environmental differences. ...
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Purpose Evidence indicates the existence of an association between socioeconomic status (SES) and the prevalence of myopia in the adult population. In contrast, there are limited studies investigating this association in children. The purpose of this study was to investigate the association between the presence of myopia in 8-year-old children from southern Europe and SES defined as parental educational level and employment status. Methods Participants aged 8 years old were recruited from 16 schools located in Terrassa, Spain (n = 813). Ten of these schools were classified as “high complexity” schools (low SES). Refractive error was assessed using non-cycloplegic retinoscopy. Parental questionnaires were used to gather socioeconomic information such as parental education level and employment status. Non-parametric Kruskal Wallis, Mann Whitney and Chi-square tests were used to evaluate the association between spherical equivalent (SE) and parental educational level and employment status as well as differences in the SE distribution between high-complexity and regular schools. Results Myopia was more prevalent than hyperopia in the population sample (11.1% vs 5.1 %). Chi-square tests revealed a significant association between attending “high-complexity” schools and the presence of myopia (p = 0.014). In contrast, no significant associations were found between SE and SES. A trend for higher prevalence of myopia in children whose mothers had low educational level and were unemployed was observed. Conclusions While no significant associations are found between SE and parental education or employment status, myopia is more frequently found in schools with low SES (“high-complexity” schools), suggesting a potential link between SES and childhood myopia.
... Most research on this topic has, to date, been carried out in East Asia and Australia [5][6][7][8]. However, over the past 50 years, the prevalence of myopia in children in the UK has doubled [9], and the pace may be accelerating since the COVID19-pandemic lockdowns [10]. Children from Asian and Black families have a 9× and 3× higher risk than White children, respectively, of developing myopia [11]. ...
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Only a few recent studies report direct assessment or monitoring of light levels in the indoor learning environment, and no consensus exists on minimum exposures for children’s health. For instance, myopia is a common progressive condition, with genetic and environmental risk factors. Reduced daylight exposure, electric lighting changes, increased near-work for school children, greater academic focus, and use of display screens and white boards may have important detrimental influences. Published assessment methods had varied limitations, such as incomplete compliance from participants wearing light loggers for extended periods. Climate-Based Daylight Modelling is encouraged in UK school design, but design approaches are impractical for post-occupancy assessments of pre-existing classrooms or ad hoc modifications. In this study, we investigated the potential for direct assessment and monitoring of classroom daylight and lighting measurements. Combined with objective assessments of outdoor exposures and class time use, the classroom data could inform design and light exposure interventions to reduce the various health impacts of inadequate daylight exposure. The relevant environmental measure for myopia depends on the hypothesized mechanism, so the illuminance, spectral distribution, and temporal light modulation from the electric lighting was also assessed.
... Lingham et al.'s study [22] is the most recent to develop a mathematical model for estimating AL. The data used to develop the model were obtained from several studies carried out in Ireland [37][38][39] and China [40]. The devices used to measure the variables varied between studies. ...
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Determining the axial length (AL) of the eye is of significant interest in the management of myopia. However, the devices that allow this value to be obtained are either expensive, for example, optical biometers, or inconvenient for use in pediatric population, such is the case with ultrasound biometers. Therefore, this study aimed to develop a mathematical model for estimating the AL value based on easily obtainable variables, with the novel addition of body height to the analysis. A total of 170 eyes of 85 myopic volunteers (mean age of 10.8 ± 1.45 years, ranging from 7 to 14 years) were included in the analysis. Participants underwent anamnesis, keratometry by NVISION-K 5001, subjective refraction by an optometrist, AL measurement by the Topcon MYAH biometer, and body height measurement. Spearman’s correlation test was employed to analyze the relationships between AL and keratometry, spherical equivalent, body height (Sperman’s correlation, all r ≥ 0.267, all p < 0.001), and age (Spearman’s correlation, p = 0.081). Subsequently, multiple regression analysis was conducted on the variables that demonstrated a previous correlation. The mathematical model obtained permits the estimation of AL based on average keratometry, spherical equivalent, and body height. This model is significant (p < 0.001) and explains 82.4% of AL variability.
... The mean rate of SE change in high-risk children and those with myopia were − 0.33 ± 0.37D/year and − 0.08 ± 0.55D/ year, respectively. The Northern Ireland Childhood Errors of Refraction (NICER) reported that the estimated annual median change of participants with 6-7 years old was − 0.23D over the six-year period [40]. Hu Y et al. [41] reported that the mean rate of SE change in the children aged 5.12 years(IQR, 4.12-5.76 ...
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Background Although school screenings identify children with vision problems and issue referrals for medical treatment at an ophthalmic hospital, the effectiveness of this approach remains unverified. Objective To investigate the impact of ophthalmic clinical services on the onset and progression of myopia in preschool children identified with vision impairment. Methods Using data from the Shanghai Child and Adolescent Large-scale Eye Study (SCALE), this retrospective cohort study evaluated the visual development of children from three districts—Jing’an, Minhang, and Pudong—which are representative of geographic diversity and economic disparity in Shanghai’s 17 districts. Initially, in 2015, the study encompassed 14,572 children aged 4–6 years, of whom 5,917 needed a referral. Our cohort consisted of 5,511 children who had two or more vision screenings and complete personal information over the follow-up period from January 2015 to December 2020. We divided these children into two groups based on their initial spherical equivalent (SE): a High-risk group (SE > -0.5 D) and a Myopia group (SE ≤ -0.5 D). Within each of these groups, we further categorized children into Never, Tardily, and Timely groups based on their referral compliance to compare the differences in the occurrence and progression of myopia. Cox proportional models were applied to estimate hazard ratios (HRs) for myopia incidence per person-years of follow-up in High-risk group. Generalized additive models(GAM) was used to calculating the progression for annual spherical equivalent changes in all children. Results Of the 5,511 preschool children (mean age, 5.25 years; 52.24% male) who received a referral recommendation, 1,327 (24.08%) sought clinical services at an ophthalmic hospital. After six years of follow-up, 65.53% of children developed myopia. The six-year cumulative incidence of myopia in the Never, Tardily, and Timely groups was 64.76%, 69.31%, and 57.14%, respectively. These percentages corresponded to hazard ratios (HRs) of 1.31 (95% CI, 1.10–1.55) for the Tardily group and 0.55 (95% CI, 0.33–0.93) for the Timely group, compared with the Never group. The HRs were adjusted for age, sex, and SE at study entry. Interestingly, the Timely group showed significantly less SE progression than the other groups (P < 0.001), and SE progression was higher in the High-risk group (-0.33 ± 0.37D/year) than in children with myopia (-0.08 ± 0.55D/year). Conclusion Timely utilization of ophthalmic clinical services among children aged 4 to 6 years who fail school vision screenings can significantly reduce the incidence of myopia and slow SE progression.
... No entanto, estudos epidemiológicos demonstram um aumento em populações europeias. Por exemplo, a proporção de míopes no Reino Unido aumentou para o dobro nos últimos 50 anos em crianças com idades compreendidas entre 10 e 16 anos, atingindo os 18,6% em crianças com dezassete anos de idade no estudo The Northern Ireland Childhood Errors of Refraction (NICER) 4 . ...
Article
RESUMO: Introdução-A miopia é um erro refrativo cujos raios paralelos provenientes do infinito focam antes do plano da retina. Globalmente a prevalência da miopia está a aumentar, sendo a sua progressão controlada através de diversos métodos, nomeadamente lentes de desfo-cagem periférica, como é o exemplo das lentes de contacto MiSight® 1 day. Objetivos-Avaliar a progressão da miopia em crianças que usaram lentes de contacto MiSight® 1 day. Métodos-Foi implementado um estudo observacional descritivo, retrospetivo e do tipo série de casos. Os dados foram recolhidos após consulta de registo clínico num estabelecimento comercial de ótica, local onde as lentes de contacto foram adaptadas. Foram incluídas crianças com miopia que iniciaram o tratamento com as lentes de contacto MiSight® 1 day para controlo da progressão da miopia. A eficácia do tratamento foi avaliada através da medição do erro refrativo (equiva-lente esférico) antes, durante e após o início do tratamento. Resultados-Foram incluídas cinco crianças, duas do género masculino e três do feminino, com idades entre os sete e quinze anos. A duração do tratamento variou entre 19 e 61 meses. A progressão da miopia durante o tratamento variou entre 0.00 e-1.75 D. Discussão-Todas as crianças que integraram o estudo demonstraram uma diminuição da progressão da miopia quando comparada com a progressão da miopia antes do tratamento (0.00 e-2.25 D), bem como com a progressão que seria expectável sem tratamento (-1.10 e-2.75 D). Conclusões-O uso da lente de contacto MiSight® 1 day proporcionou um maior controlo na progressão da miopia quando comparado com a progressão que seria expectável sem a utilização da mesma. Palavras-chave: Miopia; Crianças; Lentes de contacto; MiSight® 1 day; Tratamento da miopia. ABSTRACT: Introduction-Myopia is a refractive error where parallel rays coming from infinity focus before the retinal plane. Globally the prevalence of myopia has increased, and its progression can be controlled by various methods, including peripheral defocusing lenses, such as the MiSight® 1-day contact lenses. Objectives-Evaluate the progression of myopia in children who wore MiSight® 1-day contact lenses. Methods-This was an observational, descriptive, retrospective , and case series study. Data was collected from clinical registries in an Optician's office, where the contact lenses were fitted. Children with myopia who started treatment with MiSight® 1 day contact lenses to control myopia progression were included. Treatment efficacy was assessed by measuring refractive error (spherical equivalent) before, during, and after initiation of treatment. Results-Five children were included, two males and three females, aged between seven and fifteen years. The duration of treatment ranged from 19 to 61 months. Myopia progression during treatment ranged from 0.00 to-1.75 D. Discussion-All children in the study showed a decrease in myopia progression compared to myopia progression before treatment (0.00 and-2.25 D), as
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Aims To evaluate the myopia control efficacy of Diffusion Optics Technology (DOT) spectacle lenses in children over a 4-year treatment period. Methods CYPRESS Part 1 ( NCT03623074 ) was a 3-year multicentre, randomised, controlled, double-masked trial comparing two investigational spectacle lens DOT designs (Test 1, Test 2) and standard single vision Control lenses in 256 North American children aged 6–10 years. Children completing Part 1 (n=200) were invited to enrol in CYPRESS Part 2 ( NCT04947735 ) for an additional 1-year period. In Part 2, Test 1 (n=35) and Control groups (n=42) continued with their original lens assignment and the Test 2 group (n=21) were crossed over to Test 1 (DOT 0.2) lenses. The co-primary endpoints were change from baseline in axial length (AL) and cycloplegic spherical equivalent refraction (cSER). Results Test 1 spectacle lenses demonstrated superiority to the Control in both co-primary endpoints: with a difference between means (Test 1−Control) of −0.13 mm for AL (p=0.018) and 0.33 D for cSER (p=0.008) in Part 1 and −0.05 mm for AL (p=0.038) and 0.13 D for cSER (p=0.043) in Part 2. Comparing treatment effects in Part 1 and 2 suggests that COVID-19 public health restrictions negatively impacted treatment efficacy in study years 2 and 3. Conclusion DOT 0.2 spectacle lenses are safe and effective at reducing myopia progression, with additional benefit evident in year 4 of wear. These results support the hypothesis that a mild reduction in retinal contrast can slow myopia progression in young children. The unprecedented disruption in participant schooling and lifestyle during the COVID-19 pandemic may have depressed treatment efficacy in Part 1.
Article
Aim The aim of this research was to study the distribution and patterns of refractive errors (REs) among school children and the incidence of amblyopia in each type. Patients and methods This is an observational nonrandomized population-based cross-sectional study that included children aged 6-18 years attending the Outpatient Clinic of Al-Zahraa University Hospital, Al-Azhar University, Cairo, Egypt. All children were subjected to comprehensive eye examination including best corrected visual acuity (BCVA), expressed in LogMAR, cycloplegic REs that was documented using a NIDEK auto-refractometer-keratometer, cover-uncover testing, and fundus examination. The prevalence of REs, amblyopia, and anisometropia was estimated. Results The study included 960 children (1920 eyes), with a mean age of 13.08±3.41 years. Emmetropia was found in 834 (43.4%) eyes, while myopia was reported in 587 (30.6%) eyes, hypermetropia in 114 (5.9%) eyes, and myopic astigmatism in 385 (20%) eyes. Anisometropia was reported in 65 (6.77%) children, while amblyopia was found in 49 (5.1%) eyes. The amblyopia prevalence was statistically significantly higher among the hypermetropic group (3.9%) than the myopic astigmatism group (1.2%), ( P = 0.031). Conclusion The overall prevalence of REs among the examined children was 56.6% mainly myopia followed by myopic astigmatism and lastly hypermetropia. This draws the attention to the increased incidence of myopia which needs further social studies.
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Detailed clinical assessment is critical to allow sensitive evaluation of the eye and its management. As technology advances, these assessment techniques can be adapted and refined to improve the detection of pathological changes of ocular tissue and their impact on visual function. Enhancements in optical medical devices including spectacle, contact, and intraocular lenses have allowed for a better understanding of the mechanism and amelioration of presbyopia and myopia control. Advancements in imaging technology have enabled improved quantification of the tear film and ocular surface, informing diagnosis and treatment strategies. Miniaturized electronics, large processing power, and in-built sensors in smartphones and tablets capacitate more portable assessment tools for clinicians, facilitate self-monitoring and treatment compliance, and aid communication with patients. This article gives an overview of how technology has been used in many areas of eye care to improve assessments and treatment and provides a snapshot of some of my studies validating and using technology to inform better evidence-based patient management.
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To investigate whether myopia is becoming more common across Europe and explore whether increasing education levels, an important environmental risk factor for myopia, might explain any temporal trend. Meta-analysis of population-based, cross-sectional studies from the European Eye Epidemiology (E(3)) Consortium. The E(3) Consortium is a collaborative network of epidemiological studies of common eye diseases in adults across Europe. Refractive data were available for 61 946 participants from 15 population-based studies performed between 1990 and 2013; participants had a range of median ages from 44 to 78 years. Noncycloplegic refraction, year of birth, and highest educational level achieved were obtained for all participants. Myopia was defined as a mean spherical equivalent ≤-0.75 diopters. A random-effects meta-analysis of age-specific myopia prevalence was performed, with sequential analyses stratified by year of birth and highest level of educational attainment. Variation in age-specific myopia prevalence for differing years of birth and educational level. There was a significant cohort effect for increasing myopia prevalence across more recent birth decades; age-standardized myopia prevalence increased from 17.8% (95% confidence interval [CI], 17.6-18.1) to 23.5% (95% CI, 23.2-23.7) in those born between 1910 and 1939 compared with 1940 and 1979 (P = 0.03). Education was significantly associated with myopia; for those completing primary, secondary, and higher education, the age-standardized prevalences were 25.4% (CI, 25.0-25.8), 29.1% (CI, 28.8-29.5), and 36.6% (CI, 36.1-37.2), respectively. Although more recent birth cohorts were more educated, this did not fully explain the cohort effect. Compared with the reference risk of participants born in the 1920s with only primary education, higher education or being born in the 1960s doubled the myopia prevalence ratio-2.43 (CI, 1.26-4.17) and 2.62 (CI, 1.31-5.00), respectively-whereas individuals born in the 1960s and completing higher education had approximately 4 times the reference risk: a prevalence ratio of 3.76 (CI, 2.21-6.57). Myopia is becoming more common in Europe; although education levels have increased and are associated with myopia, higher education seems to be an additive rather than explanatory factor. Increasing levels of myopia carry significant clinical and economic implications, with more people at risk of the sight-threatening complications associated with high myopia. Copyright © 2015 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.
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Purpose: To explore risk factors for myopia in 12-13-year-old children in Northern Ireland (NI). Methods: Stratified random sampling was performed to obtain representation of schools and children. Cycloplegia was achieved using cyclopentolate hydrochloride 1%. Distance autorefraction was measured using the Shin-Nippon SRW-5000. Height and weight were measured. Parents and children completed a questionnaire including questions on parental history of myopia, sociodemographic factors, childhood levels of near vision and physical activity to identify potential risk factors for myopia. Myopia was defined as spherical equivalent ≤-0.50D in either eye. Results: Data from 661 white children aged 12-13-years showed that regular physical activity was associated with a lower estimated prevalence of myopia as compared with sedentary lifestyles (odds ratio (OR) =0.46 adjusted for age, sex, deprivation score, family size, school type, urbanicity, 95%CI 0.23 to 0.90, p for trend = 0.027). The odds of myopia were more than 2.5 times higher amongst children attending academically-selective-schools (adjusted OR=2.66, 95%CI 1.48 to 4.78) compared to non- academically-selective-schools. There was no evidence of an effect of urban versus non-urban environment on the odds of myopia. Compared to children with no myopic parents, children with one or both parents being myopic were 2.91 times (95%CI 1.54 to 5.52) and 7.79 times (95%CI 2.93 to 20.67) more likely to have myopia, respectively. Conclusions: In NI children parental history of myopia and type of schooling, are important determinants of myopia. The association between myopia and an environmental factor such as physical activity levels may provide insight into preventive strategies. Copyright © 2015 by Association for Research in Vision and Ophthalmology.
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Studies show great variability in the prevalence of hyperopia among children. This study aimed to synthesize the existing knowledge about hyperopia prevalence and its associated factors in school children and to explore the reasons for this variability. This systematic review followed PRISMA guidelines. Searching several international databases, the review included population- or school-based studies assessing hyperopia through cycloplegic autorefraction or cycloplegic retinoscopy. Meta-analysis of hyperopia prevalence was performed following MOOSE guidelines and using the random effects model. The review included 40 cross-sectional studies. The prevalence of hyperopia ranged from 8.4% at age six, 2-3% from 9 to 14 years and approximately 1% at 15 years. With regard to associated factors, age has an inverse association with hyperopia. The frequency of hyperopia is higher among White children and those who live in rural areas. There is no consensus about the association between hyperopia and gender, family income and parental schooling. Future studies should use standardized methods to classify hyperopia and sufficient sample size when evaluating age-specific prevalence. Furthermore, it is necessary to deepen the understanding about the interactions among hyperopic refractive error and accommodative and binocular functions as a way of identifying groups of hyperopic children at risk of developing visual, academic and even cognitive function sequelae.
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Purpose To determine the association between ocular sun exposure measured by conjunctival ultraviolet autofluorescence and myopic refractive error in young adults. Design Cross-sectional study Methods Setting: Population-based cohort in Western Australia Study population 1344 mostly white subjects aged 19-22 years in the Western Australian Pregnancy Cohort (Raine) Eye Health Study Observation procedures Cycloplegic autorefraction, conjunctival ultraviolet autofluorescence photography, participant questionnaire Main Outcome Measures Prevalence of myopic refractive error (spherical equivalent less than -0.50 diopters) and area of conjunctival ultraviolet autofluorescence in mm2 Results There was an inverse relationship between myopic refractive error and ocular sun exposure, with more than double the prevalence of myopia in the lowest quartile of conjunctival autofluorescence than the highest quartile (33.0% vs 15.6%). Median area of autofluorescence was significantly lower in myopes than non-myopes (31.9mm2 vs 47.9mm2, p<0.001). These differences remained significant after adjustment for age, gender, parental history of myopia and subject level of education. The use of corrective lenses did not explain the lower conjunctival autofluorescence observed in myopes. Conclusions In this young adult population, myopic refractive error was inversely associated with objectively measured ocular sun exposure, even after adjustment for potential confounders. This further supports the inverse association between outdoor activity and myopia.
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Purpose: To explore 3-year change in spherical refractive error and ocular components among white Northern Irish schoolchildren. Methods: Baseline data were collected among 6- to 7-year-old and 12- to 13-year-old children. Three years after baseline, follow-up data were collected. Cycloplegic refractive error and ocular components measurements (axial length [AL], anterior chamber depth [ACD], corneal radius of curvature [CRC]) were determined using binocular open-field autorefraction and ocular biometry. Change in spherical equivalent refractive error (SER) and ocular components were calculated. Results: A statistically significantly greater change in SER was found between 6 to 7 years and 9 to 10 years (younger cohort) compared to between 12 to 13 years and 15 to 16 years (older cohort) (-0.38 diopter [D] and -0.13 D, respectively) (P<0.001). A statistically significantly greater change in AL was found among the younger compared to the older cohort (0.48 mm and 0.14 mm, respectively) (P<0.001). Change in ACD was minimal across both groups (0.12 mm younger and 0.05 mm older cohort) as were changes in CRC. Change in SER was associated with change in AL in both age groups (both P<0.01). Conclusions: There is a greater change in both spherical refractive error and axial length in younger children when compared with teenagers. Although increase in axial length drives refractive change during childhood and teenage years, lens compensation continues to occur in an attempt to maintain emmetropia. White children living in Northern Europe demonstrate dramatically less change in spherical refractive error over a fixed period of time than their East Asian counterparts. In contrast, they appear to exhibit more rapid myopic progression than UK children studied in the mid-20th century.
Chapter
There are only limited data and unreliable records determining the size of the Tibetan population. This chapter attempts to review relevant information derived from a vast pool of literature, particularly from before the 1950s, to compile data regarding the Tibetan population. Censuses pursued by the People's Republic of China have been derived from indirect surveys or local authority reports. The census staff were able to conduct direct interviews and record information about the population in 1982. While data from 1990 and 2000 covered all of Tibet's regions, the data from these three censuses together have been widely accepted, even by the United Nations. Using the opportunity to look into Tibet's population dynamics, this chapter focuses on studying the changes experienced by the population particularly in terms of geographic distribution patterns.
Article
Purpose: The purpose of this study was to investigate the long-term outcome of high hypermetropic refractive errors in childhood. Methods: We retrospectively reviewed data from the clinical records of 164 children with spherical equivalent (SE) hypermetropic refractive errors in three medical centers collected over 29 years. Refractive errors between +1.00 and +3.00 diopter (D) on initial examination were classified as mild hypermetropia and those +5.00 D or greater were classified as high hypermetropia. The four variables studied were, age, refractive error, strabismus, and gender. The rate of reduction in hypermetropic refractive error was calculated over time in years. We identified subgroups according to age, gender, and initial refractive error. Results: Seventy-eight children with high hypermetropia and 86 children with mild hypermetropia were studied. High hypermetropia was detected at a mean age of 3.3 years, while mild hypermetropia was detected at a mean 4 years of age. The mean follow-up was 6.6 years for high hypermetropia and 6.4 years for mild hypermetropia. Over the follow-up period, children in all subgroups tended to reduce their refractive errors. The reduction in refraction power was small for both mild and high hypermetropic refractive errors. Amblyopia in the high hypermetropia group was more common and more refractory to treatment. Conclusions: Most children with hypermetropia of less than +3.00 D experience a reduction in hyperopic refractive error over time and will outgrow any need for corrective lenses. Children with hyperopia greater than +5.00 D will not experience a significant reduction in the power of the refractive error.
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This article presents an analysis of the population-density distributions present in 147 Polish towns and cities of 30,000 inhabitants or more, as of 2002. The determination of these distributions was by reference to concentric rings 1 km across, with numbers of inhabitants being determined on the basis of aggregate data for 14,000 statistical districts, the numbers per centre ranging from 16 in the case of Łuków to 1346 in Warsaw. The districts in question cover a total area of 9800 km2 and account overall for some 16.8 million inhabitants of Poland. This makes this the most exhaustive analysis of population-density distributions ever carried out for the country. The results of the analyses point to the widespread presence of function-related distributions of population density in the largest Polish cities, albeit irrespective of their size as referred to more precisely. A clear majority (88%) of centres are characterised by a distribution model in line with either the exponential or power functions, or derivatives. The 'crater effect' indicative of depopulation in city centres is met with only rarely, in just a very few towns and cities, this perhaps reflecting the relative youthfulness of Poland's urban areas. © Institute of Geography and Spatial Organization Polish Academy of Sciences.
Article
The aim of the study was to evaluate the level of agreement between the 'Representative Value' (RV) of refraction obtained from the Shin-Nippon NVision-K 5001 instrument with values calculated from individual measurement readings using standard algebraic methods. Cycloplegic autorefraction readings for 101 myopic children aged 8-13 years (10.9 ± 1.42 years) were obtained using the Shin-Nippon NVision-K 5001. Ten autorefractor measurements were taken for each eye. The spherical equivalent (SE), sphere (Sph) and cylindrical component (Cyl) power of each eye were calculated, firstly, by averaging the 10 repeated measurements (Mean SE, Mean Sph and Mean Cyl), and secondly, by the vector representation method (Vector SE, Vector Sph and Vector Cyl). These calculated values were then compared with those of RV (RV SE, RV Sph and RV Cyl) provided by the proprietary software of the NVision-K 5001 using one-way analysis of variance (anova). The agreement between the methods was also assessed. The SE of the subjects ranged from -5.37 to -0.62 D (mean ± SD, = -2.89 ± 1.01 D). The Mean SE was in exact agreement with the Vector SE. There were no significant differences between the RV readings and those calculated using non-vectorial or vectorial methods for any of the refractive powers (SE, p = 0.99; Sph, p = 0.93; Cyl, p = 0.24). The (mean ± SD) differences were: RV SE vs Mean SE (and also RV SE vs Vector SE) -0.01 ± 0.06 D; RV Sph vs Mean Sph, -0.01 ± 0.05 D; RV Sph vs Vector Sph, -0.04 ± 0.06 D; RV Cyl vs Mean Cyl, 0.01 ± 0.07 D; RV Cyl vs Vector Cyl, 0.06 ± 0.09 D. Ninety-eight percent of RV reading differed from their non-vectorial or vectorial counterparts by less than 0.25 D. The RV values showed good agreement to the results calculated using conventional methods. Although the formula used to calculate RV by the NVision-K 5001 autorefractor is proprietary, our results provide validation for the use of RV measurements in clinical practice and vision science research.
Article
Purpose: To determine the prevalence, incidence, and change in refractive errors for Australian schoolchildren and examine the impact of ethnicity and sex. Design: Population-based cohort study. Participants: The Sydney Adolescent Vascular and Eye Study, a 5- to 6-year follow-up of the Sydney Myopia Study, examined 2760 children in 2 age cohorts, 12 and 17 years. Longitudinal data were available for 870 and 1202 children in the younger and older cohorts, respectively. Methods: Children completed a comprehensive examination, including cycloplegic autorefraction (cyclopentolate 1%; Canon RK-F1). Myopia was defined as ≤-0.50 diopters (D) and hyperopia as ≥+2.00 D right eye spherical equivalent refraction. Main outcome measures: Baseline and follow-up refraction. Results: Prevalence of myopia increased between baseline and follow-up for both the younger (1.4%-14.4%; P<0.0001) and older cohorts (13.0%-29.6%; P<0.0001). The annual incidence of myopia was 2.2% in the younger cohort and 4.1% in the older. Children of East Asian ethnicity had a higher annual incidence of myopia (younger 6.9%, older 7.3%) than European Caucasian children (younger 1.3%, older 2.9%; all P<0.0001). The prevalence of myopia in European Caucasian children almost doubled between the older (4.4%; 95% confidence interval [CI], 3.0-5.8) and younger samples (8.6%; 95% CI, 6.7-10.6) when both were aged 12 years. Children with ametropia at baseline were more likely to have a significant shift in refraction (hyperopia: odds ratio [OR], 3.4 [95% CI, 1.2-9.8]; myopia: OR, 6.3 [95% CI, 3.7-10.8]) compared with children with no refractive error. There was no significant difference in myopia progression between children of European Caucasian and East Asian ethnicity (P = 0.7). Conclusions: In Sydney, myopia prevalence (14.4%, 29.6%) and incidence (2.2%, 4.1%) was low for both age cohorts, compared with other locations. However, in European Caucasian children at age 12, the significantly higher prevalence of myopia in the younger sample suggests a rise in prevalence, consistent with international trends. Progression of myopia was similar for children of East Asian and European Caucasian ethnicity, but lower than reported in children of East Asian ethnicity in East Asia, suggesting that environmental differences may have some impact on progression.