14
OPHTALMOLOGY
Zdrav Vestn | January  – February 2022 | Volume 91 | https://doi.org/10.6016/ZdravVestn.3156
Copyright (c) 2022 Slovenian Medical Journal. This work is licensed under a
Creative Commons Attribution-NonCommercial 4.0 International License.
Review of vision screening referrals in children
Pregled napotitev v okviru presejalnih pregledov vidne ostrine pri otrocih
Alma Kurent,1 Dragica Kosec2
Abstract
Background: Childhood vision screening is aimed at the detection of reduced vision due to amblyopia, thus enabling early 
diagnosis and timely intervention. The purpose of the study was to review the demographics and visual parameters of 
children referred to the ophthalmologist at Community Health Centre Ljubljana from Slovenian community-based vision 
screening program and define the visual outcome after treatment in children with amblyopia.
Methods: Retrospective medical records review of children referred from community-based vision screening program for 
further assessment. Medical records were reviewed to determine findings from ophthalmic assessments, treatment re-
ceived, and visual acuity at the final visit. The main outcome measures were the cause of visual impairment and the visual 
acuity at the final follow-up visit. 
Results: From 439 children (mean age 7.3 +/- 3.7 years) referred from community-based vision screening program, 75 
children (17%; mean age 5.3 +/- 2.6 years) had amblyopia and received treatment. They had amblyogenic refractive error 
(3.67 +/- 2.44 diopters of sphere and 1.86 +/- 1.23 diopters of astigmatism) with uncorrected visual acuity on average 0.32 
+/- 0.28 logMAR in the worse eye. Visual outcomes after treatment were good with a visual acuity of 0.04 +/- 0.07 logMAR in 
the worse eye, 60% of them had a visual acuity of 0.00 logMAR (40/40).
Conclusion: Children with amblyopia in the presented clinical sample were mostly diagnosed and treated before the 
school-age. These children showed significant improvement in visual acuity in the amblyopic eye.
Izvleček
Izhodišča: Cilj presejalnih pregledov vida pri otrocih je zgodnje odkrivanje znižane vidne ostrine, kar omogoča pravočasno 
zdravljenje slabovidnosti. Namen študije je pregledati demografske značilnosti in parametre vidne funkcije otrok, napo-
tenih na pregled k oftalmologu v Zdravstvenem domu Ljubljana zaradi slabšega vida ob presejalnem pregledu vida. To je 
del slovenskega programa preventivnih pregledov otrok in mladostnikov. Namen je tudi opredeliti vidno funkcijo otrok z 
ambliopijo po zdravljenju.
1 Community Health Centre Ljubljana, Ljubljana, Slovenia
2 Eye Hospital, University Medical Centre Ljubljana, Ljubljana, Slovenia
Correspondence / Korespondenca: Alma Kurent, e: alma.kurent@gmail.com
Key words: vision screening; amblyopia; children; refraction; visual acuity
Ključne besede: presejalni pregled vida; slabovidnost; otroci; refrakcija; vidna ostrina
Received / Prispelo: 2. 7. 2020 | Accepted / Sprejeto: 10. 9. 2020
Cite as / Citirajte kot: Kurent A, Kosec D. Review of vision screening referrals in children. Zdrav Vestn. 2022;91(1–2):14–21. DOI: https://
doi.org/10.6016/ZdravVestn.3156
eng slo element
en article-lang
10.6016/ZdravVestn.3156 doi
2.7.2020 date-received
10.9.2020 date-accepted
Ophtalmology Oftalmologija discipline
Original scientific article Izvirni znanstveni članek article-type
Review of vision screening referrals in children Pregled napotitev v okviru presejalnih pregledov vidne ostrine pri otrocih article-title
Review of vision screening referrals in children Pregled napotitev v okviru presejalnih pregledov vidne ostrine pri otrocih alt-title
vision screening, amblyopia, children, refrac-
tion, visual acuity
presejalni pregled vida, slabovidnost, otroci, 
refrakcija, vidna ostrina kwd-group
The authors declare that there are no conflicts 
of interest present.
Avtorji so izjavili, da ne obstajajo nobeni 
konkurenčni interesi. conflict
year volume first month last month first page last page
2022 91 1 2 14 21
name surname aff email
Alma Kurent 1 alma.kurent@gmail.com
name surname aff
Dragica Kosec 2
eng slo aff-id
Community Health Centre 
Ljubljana, Ljubljana, Slovenia
Zdravstveni dom Ljubljana, 
Ljubljana, Slovenija 1
Eye Hospital, University Medical 
Centre Ljubljana, Ljubljana, 
Slovenia
Očesna klinika, Univerzitetni 
klinični center Ljubljana, 
Ljubljana, Slovenija
2
Slovenian Medical Journallovenian Medical Journal
15
ORIGINAL SCIENTIFIC ARTICLE
Review of vision screening referrals in children 
1 Introduction
Amblyopia, defined as poor vision due to abnormal 
visual experience early in life (1,2), affects approximately 
1%–5% of the population (1,3-5). There is no obvious 
ocular pathology underlying the reduced visual acuity 
but rather, there is a predisposing condition, such as 
strabismus (disrupting the binocular vision develop-
ment), refractive error or media opacification (e.g. con-
genital cataract) that influences the development of vi-
sual acuity after birth (1). The earlier in post-natal visual 
experience the predisposing condition presents and the 
longer the duration of abnormal visual experience the 
more profound the level of amblyopia (1).
Amblyopia can lead to a permanent loss of vision 
with an impact on the quality of life. In the study from 
Chua and Mitchell it was found that people with ambly-
opia also had almost three times the risk of visual im-
pairment in their better-seeing eye compared to people 
without amblyopia (6). Impaired visual acuity (VA) was 
also found to be associated with an increased risk of falls 
(7) and death (8).
Amblyopia is also the most common cause of pre-
ventable vision loss in children (9). Treatment can be 
highly successful with more than 75% of children, less 
than 7 years of age having a significant improvement in 
the moderate amblyopic eye (to 20/30 or better) as a re-
sult of the treatment (10). The principle of treating in-
cludes clearing any image blur and encouraging the use 
of the amblyopic eye through preventing the use of the 
better-seeing eye (2). After a maximum improvement 
in visual acuity with spectacles, which is usually great-
est over the first few weeks of wearing glasses (11), the 
treatment options for the remaining amblyopia include 
patching or atropine penalization of the fellow eye (9). 
Children with a visually significant anatomic abnormal-
ity must be approached on an individual basis (12).
Children with unilaterally reduced vision, especially 
Metode: Retrospektivni pregled dokumentacije otrok, napotenih po presejalnem pregledu v nadaljnjo obravnavo pri of-
talmologu. Analizirali smo ugotovitve, pridobljene ob oftalmološkem pregledu, zdravljenje in ostrino vida ob zadnjem 
obisku. Glavni merili za izid sta bili vzrok za okvaro vida in ostrina vida ob zadnjem obisku.
Rezultati: V študijo je bilo vključenih 439 otrok (povprečna starost 7,3 +/- 3,7 leta), napotenih po presejalnem pregledu. 75 
otrok (17 %; povprečna starost 5,3 +/- 2,6 leta) je imelo ambliogeno refraktivno napako (3,67 +/- 2,44 dioptrij sfere in 1,86 
+/- 1,23 dioptrij astigmatizma) in so jih zdravili. Nekorigirana vidna ostrina je bila pri teh otrocih 0,32 +/- 0,28 logMAR na 
slabšem očesu. Izid vidne funkcije je bil po zdravljenju dober, in sicer s končno vidno ostrino 0,04 +/-0,07 logMAR, kar 60 % 
od njih jih je imelo ostrino vida 0,00 logMAR (40/40).
Zaključek: V predstavljeni študiji so bili slabovidni otroci v večini primerov diagnosticirani in zdravljeni pred obdobjem 
šolanja. Ob sledenju se je pri teh otrocih vidna ostrina na slabovidnem očesu znatno izboljšala.
with early-onset like in amblyopia, are unlikely to be 
aware of the failure to develop normal vision in the af-
fected eye. Therefore, the primary goal of childhood 
vision screening is the detection of reduced vision due 
to amblyopia, to enable timely intervention (13). Vision 
screening is recommended throughout childhood to 
detect amblyopia early enough to allow successful treat-
ment (2,12,14-16). The prevalence of amblyopia in the 
8-year-old population screened in infancy was found 
to be 1.0% compared with 2.6% in the 8-year-old pop-
ulation that had not been screened in infancy (17). In a 
Swedish study, it was reported that with screening, sub-
sequent diagnosis, and treatment, the prevalence of deep 
amblyopia (visual acuity <0.3) has been reduced from 
2% to 0.2% (18).
The screening system in Slovenia includes the follow-
ing: within the first month of life paediatricians check 
newborns for optical media clarity. If no abnormalities 
were revealed earlier, such as latent strabismus at 18 
months of age, a systematic check-up at 3 and 4.5 years 
of age is scheduled when visual acuity is tested using pic-
ture charts (12,14,19). In a case of a poor visual acuity, 
the child would be referred to the ophthalmologist (19). 
In the existing literature, data on children referred to 
the ophthalmologist due to a poor visual acuity at vision 
screening in Slovenia is deficient. The aim of the study 
was to review the demographics and visual parame-
ters in children referred from community-based vision 
screening program in Slovenia and define the visual out-
come after treatment in children with amblyopia.
2 Methods
We conducted a retrospective study involving 
children referred to the ophthalmologist from com-
munity-based vision screening program for further 
16
OPHTALMOLOGY
Zdrav Vestn | January  – February 2022 | Volume 91 | https://doi.org/10.6016/ZdravVestn.3156
assessment. Children included in the study were those 
in whom visual acuity at screening system was not 
sufficient. Visual acuity is checked with optotypes at 
screening at the age of 3 and older. The study includ-
ed children referred between August 2018 and August 
2019 and was conducted at the Community Health 
Centre Ljubljana. Children included in the study were 
examined and treated by one ophthalmologist (A.K.). 
Parents applied their children for the exam at the par-
ticular ophthalmologist based on their personal deci-
sion. Children in the clinical sample were mostly from 
Ljubljana region.
Only children who attended the Slovenian vision 
screening program from birth were included in this 
study. Children who moved to Slovenia form oth-
er countries and were later included in the Slovenian 
screening program were excluded from the study. Chil-
dren who had already been treated by the ophthalmol-
ogist due to poor visual acuity or other reasons were 
excluded from the study.
According to the screening system protocol in Slo-
venia a five-year-old child should recognize the small-
est optotypes (0.00 logarithm of the minimum angle of 
resolution (logMAR); Snellen equivalent 40/40) from 
the distance of 5 meters at vision screening performed 
by a nurse at primary care paediatric office. A three-
year-old child should recognize all optotype lines but 
the smallest one (0.10 logMAR; Snellen equivalent 
32/40). Visual acuity is assessed monocularly. In case of 
a poor child´s cooperation, an additional appointment 
would be scheduled at the primary care paediatric of-
fice so that the visual acuity could be reliably deter-
mined. In case of a poor visual acuity, the child would 
be referred to the ophthalmologist (19,21).
At the ophthalmology office visual acuity in chil-
dren from 3 to 5 years of age was assessed in the study 
using picture chart (Topcon CC-100XP; B1 type, Top-
con, Japan) as a part of their regular ophthalmological 
examination. In children 6 to 7 years old, visual acuity 
was determined using the tumbling E chart. In chil-
dren older than 7 years of age, Snellen chart was used. 
If the child cooperated poorly using the age-appropri-
ate chart, then charts for other age groups would have 
been used. The children were occluded using occlusion 
glasses to ensure accurate monocular results.
The refraction was measured using an autorefrac-
tometer (RC-5000 Auto Refkeratometer, Tomey, USA). 
Ophthalmological exam included anterior and poste-
rior biomicroscopy. Ocular motility, ocular alignment, 
and pupillary responses were also assessed. In children 
older than 6 years of age, intraocular pressure was al-
so measured using a non-contact air-puff tonometer 
(FT-1000 Non-Contact Tonometer, Tomey, USA). Pre-
school children (<7 years old) with poor visual acui-
ty had retinoscopy generally done with 0.5% atropine. 
School children (>7 years old) with poor visual acuity 
had retinoscopy done with 2% homatropine.
Spectacles were prescribed for all amblyogenic homocystinuria and had luxation of the lenses during 
the study after she was corrected to 0.00 logMAR (Snel-
len equivalent 40/40) visual acuity in both eyes.
Children ages, uncorrected visual acuity, retinosco-
py values and visual acuity at the final follow-up visit 
(average value +/- standard deviation) were analysed.
The study design was approved by the Ethics Com-
mittee of the Community Health Centre Ljubljana (No. 
852-1/2019-2, date 7 November 2019).
3 Results
A total of 439 children (mean age 7.3 +/- 3.7 years; 
range 3 to 17 years; 238 girls and 201 boys) referred due 
to poor vision or poor cooperation at vision screening 
were included in the study (Figure 1). In this study, the 
only amblyogenic factor was found to be visually sig-
nificant refractive error. The initial ophthalmological 
exam did not reveal any other potentially amblyogen-
ic factors (e.g. cataract, strabismus) in these children. 
75/439 children (17%) had amblyogenic refractive er-
ror (mean age 5.3 +/- 2.6 years; range 3 to 16 years). In 
children with amblyogenic refractive error 20 children 
Figure 1: Flow-chart presents patients demographics and visual parameters of 439 referred children.
*Children were mainly referred from Ljubljana region and according to the data available from the Slovenian National Institute 
of Public Health for year 2018 (for year 2019 data is not yet available) in Ljubljana region 4246 children were diagnosed with eye 
disease or vision impairment at vision screening at primary care paediatric office (20).
439 children referred 
(~10% of children diagnosed with vision impairment)*
212 with reduced visual acuity
75 amblyogenic refractive error/137 non-amblyogenic refractive error
no other amblyogenic factors found
75 children (75/439; 17%) with amblyogenic refractive error
20 unilateral/55 bilateral
Figure 2: Change in visual acuity in 63 children with amblyogenic refractive error who were treated and followed-up for 
amblyopia.
Each dot presents the worse eye in each child with amblyogenic refractive error. Numbers above the dots indicate the number 
of children, where numbers are not written, dot presents one eye.
Legend: LogMAR – logarithm of the minimum angle of resolution.
uncorrected visual acuity (LogMAR)
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1
0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1
b
e
st
-c
o
rr
e
ct
e
d
 v
is
u
a
l a
cu
it
y
 (
L
o
g
M
A
R
) 
4 3 2
3
103 6
23
8
3
2
17
ORIGINAL SCIENTIFIC ARTICLE
Review of vision screening referrals in children 
refractive errors. At follow-up visits, occlusion therapy 
was prescribed if necessary. Spectacles prescription and 
occlusion therapy depended individually on the age, vi-
sual acuity and retinoscopy findings, but generally fol-
lowed the published guidelines and literature (22-25).
Amblyogenic refractive error was defined similarly 
as in the literature: hyperopia >3.50 diopters, myopia 
>3.00 diopters, anisometropia >1.5 diopters, and astig-
matism >1.5 diopters at 90° or 180°, or >1.0 diopters in 
oblique axis (2,26). Ophthalmological examination was 
done to reveal any other ocular pathology (e.g. strabis-
mus, significant ptosis or media opacities).
In two children with reduced visual acuity parents 
refused further cycloplegic refraction and the treat-
ment. Ten children from the follow-up group did not 
come for a planned check-up or were referred to oth-
er offices (e.g. for a contact lens prescription in case of 
anisometropia) and were followed-up there. These chil-
dren were not included in the follow-up group.
One child was not compliant with the prescribed 
therapy and did not wear glasses. In this child visu-
al acuity was the same after a follow-up of 9 months 
(0.10 log MAR; 32/40). One child was diagnosed with 
homocystinuria and had luxation of the lenses during 
the study after she was corrected to 0.00 logMAR (Snel-
len equivalent 40/40) visual acuity in both eyes.
Children ages, uncorrected visual acuity, retinosco-
py values and visual acuity at the final follow-up visit 
(average value +/- standard deviation) were analysed.
The study design was approved by the Ethics Com-
mittee of the Community Health Centre Ljubljana (No. 
852-1/2019-2, date 7 November 2019).
3 Results
A total of 439 children (mean age 7.3 +/- 3.7 years; 
range 3 to 17 years; 238 girls and 201 boys) referred due 
to poor vision or poor cooperation at vision screening 
were included in the study (Figure 1). In this study, the 
only amblyogenic factor was found to be visually sig-
nificant refractive error. The initial ophthalmological 
exam did not reveal any other potentially amblyogen-
ic factors (e.g. cataract, strabismus) in these children. 
75/439 children (17%) had amblyogenic refractive er-
ror (mean age 5.3 +/- 2.6 years; range 3 to 16 years). In 
children with amblyogenic refractive error 20 children 
Figure 1: Flow-chart presents patients demographics and visual parameters of 439 referred children.
*Children were mainly referred from Ljubljana region and according to the data available from the Slovenian National Institute 
of Public Health for year 2018 (for year 2019 data is not yet available) in Ljubljana region 4246 children were diagnosed with eye 
disease or vision impairment at vision screening at primary care paediatric office (20).
439 children referred 
(~10% of children diagnosed with vision impairment)*
212 with reduced visual acuity
75 amblyogenic refractive error/137 non-amblyogenic refractive error
no other amblyogenic factors found
75 children (75/439; 17%) with amblyogenic refractive error
20 unilateral/55 bilateral
Figure 2: Change in visual acuity in 63 children with amblyogenic refractive error who were treated and followed-up for 
amblyopia.
Each dot presents the worse eye in each child with amblyogenic refractive error. Numbers above the dots indicate the number 
of children, where numbers are not written, dot presents one eye.
Legend: LogMAR – logarithm of the minimum angle of resolution.
uncorrected visual acuity (LogMAR)
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1
0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1
b
e
st
-c
o
rr
e
ct
e
d
 v
is
u
a
l a
cu
it
y
 (
L
o
g
M
A
R
) 
4 3 2
3
103 6
23
8
3
2
18
OPHTALMOLOGY
Zdrav Vestn | January  – February 2022 | Volume 91 | https://doi.org/10.6016/ZdravVestn.3156
(20/75; 27%) had unilaterally and 55 children (55/75; 
73%) had bilaterally reduced visual acuity (Figure 1). 
Children with amblyogenic refractive error (3.67 +/- 
2.44 diopters of sphere and 1.86 +/- 1.23 diopters of 
astigmatism) had an uncorrected visual acuity of 0.32 
+/- 0.28 logMAR in the worse eye.
49 from 75 children (65%) with the amblyogenic re-
fractive error were diagnosed in a pre-school period. 12 
from 75 children (16%) children with the amblyogenic 
refractive error were diagnosed when they were 8 years 
of age or older. A visual acuity > 1.00 logMAR (4/40) to 
</= 0.30 logMAR (20/40) in the worse eye was found in 
8 of children diagnosed at 8 years of age or older. 
63 (63/75; 84%) children in the study with the am-
blyogenic refractive error were followed-up on average 
for 10 +/-4.7 months (range from 5 to 23 months; Ta-
ble1 and Figure 2). These children had an uncorrected 
visual acuity of 0.31 +/- 0.27 logMAR in the worse eye. 
On the final follow-up visit they had a best corrected 
visual acuity of 0.04 +/- 0.07 logMAR in the worse eye, 
38/63 (60%) of them had a visual acuity of 0.00 log-
MAR (40/40) in the worse eye (Figure 2).
Table 1: The table shows 63 children where amblyogenic refractive error was identified and were followed-up.
Age 
(years)
Number of children with 
uncorrected visual acuity </= 1.00 
logMAR (4/40) in the worse eye*
Retinoscopy values in the worse eye* 
(average value +/- standard deviation; 
absolute values in minus cylinder form)
Best corrected visual acuity 
in the worse eye* on their 
last visit (average value +/- 
standard deviation; logMAR)
Sphere (D) Cylinder (D)
3-5 2 4.75 +/- 2.25 1.88 +/- 1.13 0.15 +/- 0.21
5-6 0 / / /
6-8 2 6.63 +/- 0.88 1.88 +/- 1.59 0.10 +/- 0.07
≥8 0 / / /
Age 
(years)
Number of children with 
uncorrected visual acuity > 1.00 
logMAR (4/40) to </= 0.30 logMAR 
(20/40) in the worse eye*
Retinoscopy values in the worse eye* 
(average value +/- standard deviation; 
absolute values in minus cylinder form)
Best corrected visual acuity 
in the worse eye* on their 
last visit (average value +/- 
standard deviation; logMAR)
Sphere (D) Cylinder (D)
3-5 9 5.22 +/- 2.31 2.39 +/- 1.52 0.06 +/- 0.07
5-6 3 1.83 +/-1.61 2.17 +/- 1.26 0.01 +/- 0.03
6-8 5 4.33 +/- 2.87 2.55 +/- 1.75 0.03 +/- 0.05
≥8 5 1.99 +/- 2.47 1.63 +/- 2.2 0.13 +/- 0.03
Age 
(years)
Number of children with 
uncorrected visual acuity > 
0.30 logMAR (20/40) to </= 0.05 
logMAR (36/40) in the worse eye*
Retinoscopy values in the worse eye* 
(average value +/- standard deviation; 
absolute values in minus cylinder form)
Best corrected visual acuity 
in the worse eye* on their 
last visit (average value +/- 
standard deviation; logMAR)
Sphere (D) Cylinder (D)
3-5 17 1.61 +/- 1.99 1.67 +/- 0.95 0.03 +/- 0.05
5-6 11 2.68 +/- 2.13 1.73 +/- 0.95 0.00 +/- 0.00
6-8 5 3.90 +/- 2.18 1.50 +/- 0.94 0.00 +/- 0.00
≥8 4 3.25 +/- 2.95 0.33 +/- 0.58 0.05 +/- 0.07
Children are divided into three major groups according to their visual acuity in the worse eye (</=1.00 logMAR (4/40), >1.00 
logMAR (4/40) to </=0.30 logMAR (20/40), >0.30 logMAR (20/40) to </=0.05 logMAR (36/40)). Groups are subdivided into age 
groups. For each subgroup range of refraction is presented and final best corrected visual. Children older than 8 years who were 
developing myopia are not shown in this table.
Legend: *If both eyes had the same reduced visual acuity, right eye was chosen.
D – diopters; logMAR – logarithm of the minimum angle of resolution.
19
ORIGINAL SCIENTIFIC ARTICLE
Review of vision screening referrals in children 
4 Discussion
Children included in the presented study were mainly 
referred from Ljubljana region and according to the data 
available from the Slovenian National Institute of Public 
Health for year 2018 (for year 2019 data is not yet avail-
able) in Ljubljana region 4246 children were diagnosed 
with eye disease or vision impairment at vision screening 
at primary care paediatric office (20). 439 children from 
the study represent approximately 10% of the children 
diagnosed with eye disease or vision impairment with-
in 1 year at community-based vision screening. 17% of 
children included in the presented study were treated for 
refractive amblyopia. Visual acuity in amblyopic eyes im-
proved during the treatment, similarly as in other stud-
ies (18,27,28). Since amblyopia was unilateral in 20 cases 
and the visual acuity was normal in the other eye, there 
are chances that poor visual acuity could be unnoticed 
without vision screening. This showed the importance of 
continued childhood screening and timely treatment of 
children with amblyopia to minimize the burden of dis-
ease later in life associated with the vision loss.
The aim of childhood vision screening is the detection 
of reduced vision due to amblyopia early in life, before 
the school-age, when the results of the treatment are the 
most optimal. In the present study, 1.8% children with 
amblyogenic refractive error and a visual acuity from 
1.00 logMAR (4/40) to </= 0.30 logMAR (20/40) in the 
worse eye were diagnosed when they were 8 years of age 
or older. In these children visual acuity had been assessed 
during vision screening program also earlier but poor 
vision had not been noticed probably due to different 
reasons, such as poor child’s cooperation, peeking with 
a better-seeing eye in the unilateral poor visual acuity or 
other reasons which were beyond the scope of this study, 
but still worth exploring to avoid missing such children at 
vision screening. It is expected that some children would 
be missed on vision screening program, but keeping this 
number to minimum is the goal. In the study from Web-
ber and Wood it was summarized that the population 
studies of amblyopia indicated a prevalence of approxi-
mately three percent in untreated childhood and current 
adult populations. With the detection and treatment of 
amblyogenic condition by five years of age, the prevalence 
of clinically significant amblyopia was reduced to around 
two percent and before three years of age to around one 
per cent (1). This prevalence is lower than in our study 
where we had 1.8% of children 8 years of age or older with 
amblyogenic refractive error and moderate amblyopia 
while vision screening system in Slovenia starts screening 
with optotypes at the age of 3 years.
If visual acuity is not optimal or amblyopia risk fac-
tors are suspected to be present, refraction in cyclople-
gia of all children with reduced VA or visual symptoms 
is recommended (29). In two children from the study, 
parents did not agree with the cycloplegic refraction 
and the treatment. Treatment in children without visu-
ally significant anatomic abnormality includes wearing 
glasses and patching of the fellow eye (9,30), but compli-
ance is key to successful treatment. One of 63 children 
who were followed-up (1.6%) reported having refused to 
wear glasses, while in other study nearly half of the chil-
dren were non-compliant with the spectacle wear (27).
The improvement of visual acuity was evident in the 
follow-up group in the presented study. Visual acuity 
also improved in the older age groups where, accord-
ing to the studies, treatment should also be attempted 
(12,31-33). It would also be valuable to assess the bin-
ocular vision functions in treated children in the future. 
Follow-up time was heterogeneous in the study because 
final visual acuities were analysed for all children one 
year after the last child was referred. Additionally, some 
of the parents did not bring their children for the sched-
uled check-ups (e.g. improvement of the visual acuity 
was reported on the first follow-up visit so they did not 
come for additional check-ups) or were referred to oth-
er offices (e.g. for a contact lens prescription in case of 
anisometropia) and were followed-up there so the re-
ported follow-up times were shorter in these children.
Every second child in the study (52%) who had been 
referred to the ophthalmologist had normal visual acu-
ity at the ophthalmic exam. Poor cooperation at vision 
screening at primary care paediatric office could also 
be a factor here and probably reflects challenges in test-
ing preschool children. The success of the test depends 
mainly on the child’s cooperation and is based on visual 
acuity. Visual acuity measurement is variable in young 
children and preschool vision screening programs based 
solely on visual acuity can be in uncooperative children 
unreliable compared with other objective measure-
ments, such as retinoscopy and autorefraction (27). The 
rate of false-positive referrals in some other studies was 
from 20% (28) to almost 30% (27).
We generally used picture chart (Topcon CC-100XP; 
B1 type, Topcon, Japan) in children 3 to 5 years of age, 
Tumbling E in children 6 to 7 years of age and in older 
children Snellen charts, comparable to other paediatric 
vision screening programs (34). In the literature, the 
preferred optotypes are LEA symbols, Sloan letters, and 
HOTV, as they are standardized and validated (16,35). 
In another study it was found that in screenings where 
visual acuity is the gold standard, Tumbling E was a good 
20
OPHTALMOLOGY
Zdrav Vestn | January  – February 2022 | Volume 91 | https://doi.org/10.6016/ZdravVestn.3156
instrument for visual acuity assessment in children aged 
3 and 4 years (36). In Slovenia, picture charts are used in 
the screening program in this age group (34).
Similarly, as in vision screening in Slovenia, it was 
suggested in the literature that amblyopia screening 
should be viewed as a continuous process that oc-
curs throughout visual development (16). It was rec-
ommended that all children aged 3 to younger than 6 
years should be screened annually (best practice) or at 
least once (acceptable minimum standard) during the 
interval between their third and sixth birthdays (16). 
Exceptions to this included for example children with 
the readily observable ocular abnormalities or system-
ic conditions that have associated ocular abnormalities. 
These children should be referred directly to an ophthal-
mologist for a comprehensive eye examination (16). In 
Slovenia, children are generally screened twice between 
their third and sixth birthdays (3 and 4.5 years of age).
Limitations of the present study are that it presented a 
clinical sample, so the data obtained could not be used to 
estimate the prevalence of amblyopia in the population 
or to present the efficacy of vision screening program in 
Slovenia. Children included in the clinical sample were 
mostly from Ljubljana region, parents usually decided 
and applied for a specific institution and an ophthal-
mologist based on their personal decision. Access to the 
ophthalmologist is usually easier in the Ljubljana region 
as it may be in some other Slovenian regions so it might 
also be easier for patients and their parents to come for 
frequent check-ups and to be encouraged to follow the 
treatment plan. All of that could influence the results in 
the presented clinical sample compared to the Slovenian 
population. National systematical data on the preva-
lence of amblyopia in the population would however be 
of great value in the estimation of the vision screening 
program in Slovenia.
Also, other amblyogenic factors such as media 
opacities or strabismus were not detected in the stud-
ied group. To include children with these amblyogenic 
factors probably all referrals should be included as par-
ents often, if they notice strabismus, actively and usually 
earlier (before children could reliably read optotypes) 
seek and receive medical treatment and do not wait 
for vision screening. Data available from the Slovenian 
National Institute of Public Health for the year 2018 
(for the year 2019 data is not yet available) in Ljublja-
na region shows that among 4246 children who were 
diagnosed with eye disease or vision impairment at vi-
sion screening at primary care paediatric office, only 
141 (3%; 141/4246) were diagnosed with strabismus in 
school period or visual disorder in pre-school period 
(in pre-school period strabismus category is not shown) 
(20). The study reviewed the demographics and visual 
parameters in a group of children referred from Slove-
nian community-based vision screening program since 
no data on the topic was available in the literature. The 
study also highlighted outcomes for a group of children 
referred to the ophthalmologist due to poor vision at vi-
sion screening and showed the evident improvement of 
visual acuity in children treated for refractive amblyopia. 
In everyday clinical practice, we are faced with patients’ 
and parents’ doubts in the diagnostics and treatment of 
refractive amblyopia so we felt it was important to show 
good visual outcomes in the treated group.
5 Conclusion
Children in the presented clinical sample who were 
diagnosed and treated for amblyopia were mostly dis-
covered and their treatment was started before the 
school-age. These children showed significant improve-
ment in visual acuity in the amblyopic eye.
Conflict of interest
None declared.
Acknowledgments
The authors thank (in alphabetical order) Ema Cof, 
Elica Kenda, Laura Omerza, Davor Predojević, Nataša 
Wagner and Jasna Zabukovec for assistance with autore-
fraction, tonometry, and visual acuity assessment.
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