Original Article

High Prevalence of Asthenopia among a Population of
University Students

Hassan Hashemi1,2, MD; Mohammad Saatchi1, MS; Abbasali Yekta3, PhD; Babak Ali3, MS
Hadi Ostadimoghaddam4, PhD; Payam Nabovati5, PhD; Mohamadreza Aghamirsalim6, MD; Mehdi

Khabazkhoob7, PhD

1Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran
2Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran

3Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
4Refractive Errors Research Center, Mashhad University of Medical Sciences, Mashhad, Iran

5Rehabilitation Research Center, Department of Optometry, School of Rehabilitation Sciences, Iran University of Medical
Sciences, Tehran, Iran

6Eye Research Center, Tehran University of Medical Sciences, Tehran, Iran
7Department of Psychiatric Nursing and Management, School of Nursing and Midwifery, Shahid Beheshti University of Medical

Sciences, Tehran, Iran

ORCID:
Abbasali Yekta: https://orcid.org/0000-0003-4356-9064
Hassan Hashemi: https://orcid.org/0000-0002-2109-0856

Abstract

Purpose: To determine the prevalence of asthenopia and its associated factors in a sample of university
students in Iran.
Methods: In this cross-sectional study, participants were selected using multistage cluster sampling.
Presence of at least one of the 10 symptoms—foreign body sensation, diplopia, blurred vision, eye
swelling, dry eye, eye pain, difficulty in sustaining visual operations, decreased visual acuity, tearing, and
photophobia—was considered as asthenopia. Ocular examinations, including uncorrected/corrected visual
acuity measurement, objective/subjective refraction, cover test, amplitude of accommodation (AA), and near
point of convergence (NPC) were performed.
Results: Of the 1,462 students (mean age: 22.8 ± 3.1 years), 73% were women. The age- and gender-
standardized prevalence was 70.9% (95% confidence interval [CI]: 68.3–73.5), 39.8% (95% CI: 36.4–43.1),
and 19.7% (95% CI: 16.0–23.3) based on the presence of at least one, two, and three symptoms, respectively.
The prevalence was significantly higher in females (P = 0.048), hyperopic students (P <0.001), and astigmatic
participants (P < 0.001). The mean AA and NPC were 9.7 ± 2.6 D and 10.2 ± 4.2 D (P = 0.008) and 7.0 ± 2.1
cm and 7.7 ± 3.9 cm (P < 0.001) in participants with and without asthenopia, respectively. Multiple regression
model revealed age (28–29 years), astigmatism, and NPC as independent associated factors (odds ratios:
3.51, 1.61, and 0.91, respectively).
Conclusion: This study shows relatively high prevalence of asthenopia in university students. Demographic
factors and visual system disorders are important risk factors and timely correction of conditions may lead
to decreased asthenopia.

Keywords: Asthenopia; Astigmatism; Photophobia; Prevalence

J Ophthalmic Vis Res 2019; 14 (4): 474–482

Correspondence to:

Abbasali Yekta, PhD. Department of Optometry, School
of Paramedical Sciences, Mashhad University of Medical
Sciences, Mashhad 91838, Iran.
Email: YektaA@mums.ac.ir

Received: 30-12-2017 Accepted: 24-04-2019

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DOI: 10.18502/jovr.v14i4.5455

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How to cite this article: Hashemi H, Saatchi M, Yekta A, Ostadimoghaddam
H, Nabovati P, Aghamirsalim M, Khabazkhoob M. Asthenopia in University
Students. J Ophthalmic Vis Res 2019;14:474–482.

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Asthenopia among University Students; Hashemi et al

INTRODUCTION

Asthenopia is a general term used to define a
group of somatic or perceptive symptoms that
usually occur following computer work, reading, or
other near visual activities.[1] Headache, sore and/or
itching eyes, blurred vision, epiphora, dry eye, dou-
ble vision, photophobia, and foreign body sensa-
tion are the most common complaints, with several
studies considering the presence of at least one
of these symptoms as asthenopia.[2, 3] Few studies
have addressed the prevalence of asthenopia as
compared with studies on other ocular conditions
and diseases. However, there are reports of a
prevalence of 12.4–32.2% in children below 18
years[4] to 57% in students below 30 years.[5]
Despite contradictory reports on the causes of
asthenopia, epidemiological studies have iden-
tified three major groups of risk factors: visual
disorders, such as refractive errors and accom-
modative dysfunctions;[6, 7] psychological factors
such as daily stress and poor mental state;[8]
and environmental factors such as low ambient
lighting, nonstandard monitor brightness;[9] and
long study periods. Social networking with the
resulting near work and increased duration of
eye exposure to smartphones, laptop screen, and
tablets and educational tasks and long studying
hours at the graduate level have made students
vulnerable to asthenopic symptoms. Considering
the importance of ocular health in the educational
success and the interference of asthenopia with
visual activities resulting in learning disorders and
decreased quality of life, and because no study has
already evaluated the prevalence of asthenopia
in Iranian university students, the present study
was conducted to determine the prevalence of
asthenopia and its associated risk factors in a
sample of Iranian university students.

METHODS

The present university-based, cross-sectional
study was conducted in Kazerun, south of Iran,
in 2017. Multi-stage sampling was used to select
the participants. There are four universities in
Kazerun and each university was considered a
stratum. Next, a list of all academic majors in
each university was prepared, and each academic
major was considered a cluster. In each university,
a number of majors were randomly selected

using a random number table in proportion to
their share in the total number of majors of four
universities. Finally, a total of 27 majors were
selected. After coordinating with the Deputy of
Educational Affairs of each university, the list
of all students in each major was obtained and
each student was assigned a unique code in a
continuous manner. Subsequently, proportional
to the size of students in each major, some
numbers were randomly selected from a table
of random numbers. In the next step, students
whose unique code matched the last two (or three)
digits of the random numbers were selected.
Telephone numbers of the selected subjects were
obtained from their universities; these students
were contacted to invite them to participate in the
study after explaining its objectives.

Refractive error was considered as the main
outcome of the study. The prevalence of myopia
was selected to reach a maximum sample size.
Based on similar studies[10, 11] and considering a
prevalence of 41%, type I error of 0.05, precision
of 0.04, and a sample size of 580 were estimated.
With regard to the sampling method, a design
effect of 2.5 was considered. After an addition of
10% non-response rate to the calculated sample
size, the final sample size was 1,595 participants.

Examinations

First, uncorrected visual acuity (UCVA) was mea-
sured using Snellen eye chart at 6 meters(m).
Following this, objective refraction was calculated
using the auto-refractometer (Topcon RM-8800;
Topcon Corp., Tokyo, Japan), and the results were
refined using the Heine Beta 200 retinoscope
(Heine Optotechnik; Herrsching, Germany). Next,
subjective refraction was used to determine the
best optical correction, and the best corrected
distance and near visual acuities (BCVAs) were
recorded.

In the next stage, binocular and accommodative
examinations were performed according to the
best optical correction. First, unilateral and alter-
nate cover tests were conducted at 6 m and 40
cm, following which the magnitude of near and
distance phoria was measured using the alternate
cover test and prism bar. An accommodative target
was used for the cover test, including one line
above the BCVA on the near and distance Snellen
charts. In the next stage, Dander’s push-up method

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Asthenopia among University Students; Hashemi et al

was used to monocularly measure the near point
of accommodation (NPA) using the Royal Air Force
Rule (RAF), with a line equivalent to the visual
acuity of 20/25 as the accommodative target. The
NPA was subsequently converted to accommoda-
tive amplitude (AA) in diopters (D) by dividing
100 by NPA. Near point of convergence (NPC)
in cm was then measured by slowly moving the
accommodative target (a character one line above
the BCVA) toward the participant’s eyes along the
midline until the participant reported diplopia or the
examiner observed fusion break. After completion
of optometric examinations, cyclo-refraction was
performed by instilling two drops of 1% cyclopento-
late, separated by 5 min and repeating retinoscopy
30 min after the last drop.

Definition of Asthenopia

To be consistent with other studies, the presence
of at least one of the ten symptoms—foreign body
sensation, diplopia, blurred vision, eye swelling,
dry eye, eye pain, difficulty in sustaining visual
operations, decreased visual acuity, tearing, and
photophobia—occurring during near visual activ-
ities was considered as asthenopia. Moreover,
the prevalence of asthenopia was determined
based on the presence of two or three symp-
toms. The exclusion criteria included age > 40
years; unwillingness to participate in the study;
history of intraocular surgery and ocular trauma;
systemic conditions or diseases affecting accom-
modation and binocular vision including hormonal
or metabolic diseases and conditions such as
pregnancy, diabetes, and thyroid dysfunctions, and
neurologic diseases such as myasthenia gravis
and multiple sclerosis; the use of ocular or sys-
temic medications affecting accommodation and
binocular vision including cycloplegic drops, cen-
tral nervous system stimulants, and phenothiazine
derivates; strabismus, amblyopia; and BCVA <
20/40 in either eye.

Statistical Analysis

The Stata software version 11 (StataCorp; College
Station, TX, USA) was used for data analysis. The
prevalence of asthenopia was reported as percent-
age and 95% confidence interval (CI). To determine
the associated risk factors of asthenopia, multiple
logistic regression was used in a backward manner

by running the survey analysis command of Stata
according to the presence of at least one symptom
from the aforementioned asthenopic symptoms.
The age- and gender-standardized prevalence of
asthenopia was calculated based on the age and
gender distribution of students in 2015 using direct
standardization.

Variables evaluated in this study included age,
gender, body mass index (BMI), years of study,
anisometropia, astigmatism, spherical equivalent
(SE) of refraction, near phoria, AA, and NPC. To
determine the years of study and its effect on
asthenopia, students were divided into two groups:
< 2 years (four academic terms) and > 2 years.
According to the World Health Organization (WHO)
guidelines,[12] BMI was categorized as underweight
(< 18.5), normal (18.5–24.5), and overweight (<
24.5). Based on cycloplegic refraction, myopia and
hyperopia were defined as ≤ 0.50 and > 0.50 D of
SE, respectively. Anisometropia was defined as SE
difference ≥ 1.00 D between the eyes. Due to the
significant correlation of both eyes in AA (Pearson’s
correlation coefficient = 0.97), only the AA of the
right eye was considered for statistical analysis. P
< 0.05 was considered statistically significant.

Ethical Considerations

The Ethics Committee of the Mashhad University
of Medical Sciences approved the protocol of the
study according to the Declaration of Helsinki.
Informed consent was obtained from all partici-
pants. The students were assured that their data
would remain anonymous and confidential.

RESULTS

Of the 1,595 invited individuals, 1,462 participated
in the study. Of these selected students with a
mean age of 22.8 ± 3.1 years (range: 18–40 years),
73% were women. Based on the presence of at
least one, two, and three symptoms, the prevalence
of asthenopia calculated to be 71.2% (95% CI: 68.4–
74.0), 40.6% (95% CI: 37.7–43.4), and 19.7% (95%
CI: 16.3%–23.2%), respectively. Table 1 presents
the prevalence of asthenopia based on one, two,
and three symptoms according to gender, age, SE,
astigmatism, BMI, academic term, near phoria, and
anisometropia. As shown in Table 1, the prevalence
of asthenopia was significantly higher in females
(P = 0.048), hyperopic students (P < 0.001), and

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Asthenopia among University Students; Hashemi et al

participants with astigmatism (P < 0.001). The mean
AA was 9.7 ± 2.6 D and 10.2 ± 4.2 D in participants
with and without asthenopia, respectively (P =
0.008). The mean NPC was 7.0 ± 2.1 cm and 7.7
± 3.9 cm in asthenopic and non-asthenopic stu-
dents, respectively (P < 0.001). Figure 1 shows the
prevalence of asthenopic symptoms: photophobia
was the most common symptom (48.7%). Table 2
presents the prevalence of asthenopic symptoms
by gender. According to Table 2, the prevalence
of most of the asthenopic symptoms was higher
in females than in the male students. Table 3
presents the results of logistic regression model
for associated risk factors of asthenopia. As seen
in multiple regression model, age group of 28 to
29 years, astigmatism, and NPC were independent
associated risk factors of asthenopia with odds
ratios of 3.51, 1.61, and 0.91, respectively.

Discussion

The present study is the first of its kind to
demonstrate the prevalence of asthenopia and its
associated risk factors in students above 18 years
of age in Kazerun, south of Iran. According to our
findings and based on the presence of at least
one symptom, the prevalence of asthenopia was
calculated to be 71%, which is much higher than
the results of a similar study (57%) conducted by
Han et al in Chinese students with a mean age
of 21 years.[5] Moreover, another study showed
a prevalence of 46% for asthenopia in Indian
computer operators with a mean age of 25 years.[1]
Aakre et al[10] and Ostrovsky et al[11] evaluated
the prevalence of asthenopia in regular computer
users. The limited number of population-based
studies, especially studies on students aged 18
to 30 years, makes it difficult to compare our
results with similar studies. In other words, lack
of studies on similar age groups; use of different
criteria and outcomes, including eye strain and
fatigue,[13] and evaluation of some occupations with
more exposure to computers and monitors hinder
the comparison of the results of the present study
with other similar studies. Our findings showed
that based on at least two or three symptoms,
the prevalence of asthenopia was much higher
than that in the younger age groups in other
studies (adolescents under 18 years). In a study
by Hashemi et al,[14] the prevalence of asthenopia
based on at least two symptoms was 24% in

adolescents aged 12 to 18 years, whereas our
findings revealed a prevalence of 40% in the
university students. Considering the importance
of students in individual and social achievements,
timely diagnosis and treatment of this condition
are essential. According to the conducted stud-
ies, adequate sleep, regular intake of vegetables,
and a good mental frame play a crucial role in
preventing asthenopia.[5, 15] Therefore, consider-
ing the lifestyle of Iranian students, their life in
dormitories and lack of proper nutrition, a high
prevalence of asthenopia is not unexpected in
this group. Another point related to the high
prevalence of asthenopia is that given the vari-
ous symptoms considered for its diagnosis, each
symptom may be associated with another disease
or condition; for example, headache is one of the
most common symptoms in several diseases.[16]
According to our findings, photophobia was the
most common symptom in more than 48% of the
cases, which is not consistent with the results of
some studies that reported headache or tearing
as the most common symptom of asthenopia.[4, 17]
There exist several reasons for the sensitivity
of eye to light; however, an underlying disease
can also cause photophobia. Moreover, ocular
surface diseases may result in photophobia.[18]
The high prevalence of photophobia in our study
population is an alarm sign and warrants further
investigation into its underlying reasons. Based
on these findings, the prevalence of asthenopia
in women was around 8% and more than in
men.

There are contradictory results on the effect of
gender; moreover, some studies have failed to find
a significant effect of gender on asthenopia.[5, 19]
Contrary to our results, Han et al[5] and Agrawal et
al[10] found no significant difference in the preva-
lence of asthenopia between men and women,
whereas Shima et al[20] and Bahanderi et al[1]
reported a higher prevalence of asthenopia symp-
toms in women. Furthermore, except for foreign
body sensation, dry eye, and decreased visual
acuity, the prevalence of other symptoms was
higher in women. Different physiological structure
and pain threshold as well as different lifestyles of
boys and girls may significantly affect the odds of
developing asthenopia and asthenopic complaints.
Our findings showed that the prevalence and odds
of asthenopia increased significantly from 20 to 29
years but decreased thereafter. Moreover, Bahan-
deri et al[1] and Maccoi et al[8] have reported aging

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Asthenopia among University Students; Hashemi et al

Table 1. The prevalence of asthenopia among 1,462 participants

Number of Symptoms Total Number of Subjects

One or more P-Value Two or more Three or more

Percent (95% CI) Percent (95% CI) Percent (95% CI)

Age sex standardized 70.9 (68.3–73.5) 39.8 (36.4–43.1) 19.7 (16.0–23.3)

Sex Male 65.5 (60.8–70.2) 0.048 31.6 (26.7–36.5) 12.8 (9.8–15.8) 389

Female 73.3 (70.5–76.1) 43.8 (41.1–46.6) 22.2 (18.6–25.9) 1,073

Age group (year) 18–19 72.2 (66.9–77.9) 0.219 38.9 (30.5–47.3) 23.3 (17.6–29.1) 90

20–21 70.2 (65.5–75.0) 37.2 (32.3–42.1) 19.3 (13.5–25.0) 441

22–23 71.6 (67.4–75.8) 42.3 (38.2–46.4) 18.5 (13.8–23.2) 546

24–25 72.6 (66.8–79.4) 42.4 (35.7–49.2) 22.4 (16.4–28.5) 205

26–27 75.3 (64.8–84.8) 48.1 (31.6–64.5) 23.4 (11.5-35.3) 77

28–29 81.5 (66.2–96.9) 55.3 (41.2–69.3) 23.7 (14.9–32.5) 38

≥ 30 58.4 (45.0–71.8) 29.2 (16.5–41.9) 13.8 (4.5–23.2) 65
Refractive errors Emmetropia 70.2 (62.9–71.0) <0.001 34.3 (29.5–32.9) 15.5 (10.5–20.5) 803

Hyperopia 79.6 (73.9–78.7) 47.5 (44.8–50.1) 24.6 (20.3–28.9) 625

Myopia 79.4 (53.7–99.9) 61.7 (35.4–88.0) 29.4 (8.2–50.5) 34

Astigmatism No 68.5 (65.9–71.1) <0.001 36.7 (33.8–39.7) 16.9 (12.8–21.0) 1,030

Yes 77.7 (73.0–82.4) 49.7 (45.0–54.4) 26.3 (23.2–29.5) 432

BMI Underweight 72.7 (64.2–81.3) 0.774 40.8 (28.5–53.1) 21.0 (9.4–32.7) 147

Normal 70.6 (66.9–74.4) 40.3 (38.2–42.4) 19.1 (16.2–22.0) 986

Overweight 72.3 (68.2–76.4) 41.6 (34.9–48.4) 20.9 (16.3–25.5) 329

Semester 1–4 (≤ 2 year) 72.4 (68.3–76.5) 0.374 39.3 (35.5–43.1) 20.0 (15.3–24.7) 709
> 4 (> 2 year) 70.3 (66.7–73.8) 41.8 (38.2–45.4) 19.5 (14.4–24.5) 753

Near phoria No 70.5 (66.4–74.7) 0.141 40.4 (37.5–43.3) 19.2 (15.9–22.5) 974

Exo 71.7 (68.3–75.2) 39.8 (36.7–43.0) 19.2 (13.8–24-7) 467

Eso 86.8 (74.2–99.5) 60.5 (43.7–77.3) 34.9 (27.7–51.1) 38

Hyper 57.1 (18.5–95.8) 14.3(8.2–46.8) 14.2 (8.2–46.7) 7

Anisometropia No 70.9 (68.1–73.7) 0.283 40.0 (37.3–42.8) 19.3 (16.2–22.5) 1,409

Yes 79.2 (63.3–95.1) 54.7 (34.7–74.4) 30.1 (16.2–44.1) 53

The presence of at least one of the 10 symptoms of foreign body sensation, diplopia, blurred vision, eye swelling, dry eye, eye
pain, difficulty in sustaining visual operations, decreased visual acuity, tearing, and photophobia was considered as asthenopia.

BMI, body mass index; CI, confidence interval; Eso, esophoria; Exo, exophoria

as a determinant of asthenopia. Several studies
have confirmed age as one of the most important
determinants of different ocular disorders. How-
ever, it is reported that in addition to age,[21, 22] the
duration of computer use greatly affects the devel-
opment of asthenopia. The bachelor’s level study is
usually finished by 22 years of age, following which
students start post-graduate courses. Long years
of academic studies and increased exposure to

computers could explain the increased prevalence
of asthenopia in subjects below 30 years. Fur-
thermore, the study population has an important
role in explaining the relationship between age
and the prevalence of asthenopia. For example,
in a population-based study by Schelini et al,[23]
the highest prevalence of asthenopia was seen
in the first two decades of life and its prevalence
decreased significantly after the age of 40 years.

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Asthenopia among University Students; Hashemi et al

Table 2. Prevalence of symptoms by gender

Symptom Female (95% CI) Male (95% CI) P-value

Eye pain 15.4 (12.4–18.5) 10.5 (7.8–13.2) 0.017

Dry eye 7.5 (5.3–9.7) 5.6 (3.7–7.5) 0.211

Eye swelling 6.4 (4.2–8.5) 2.5 (0.9–4.1) 0.004

Blurred vision 23.6 (19.0–28.2) 17.4 (14.2–20.7) 0.012

Diplopia 8.39 (6.0–10.7) 4.6 (2.9–6.3) 0.015

Foreign body sensation 11.4 (8.7–14.2) 11.0 (7.9–14.2) 0.827

Photophobia 51.8 (48.3–55.3) 40.3 (32.3–48.3) < 0.001
Tearing 30.0 (25.2–34.7) 22.6 (16.5–28.7) 0.005

Decreased visual acuity 2.1 (0.8–3.4) 2.5 (1.4–3.7) 0.627

CI, confidence interval

Figure 1. The prevalence of asthenopic symptoms in 1,465 students above 18 years in the city of Kazerun.

Therefore, taking into consideration the repeated
computer work and reading, a higher prevalence of
asthenopia is expected in university students and
those in academia.

Based on the available reports, the refractive
status, especially astigmatism, is a crucial fac-
tor in developing asthenopia.[6, 19, 24] Our findings
showed that odds of asthenopia were 1.61 times
higher in astigmatic subjects as compared with
that in students without astigmatism. Moreover,
a population-based study in Brazil showed that

astigmatism was the most important risk factor
associated with asthenopia.[23] Similarly, Kotegava
et al[25] reported that proper and adequate cor-
rection of refractive errors decreased the preva-
lence of asthenopia and improved accommodative
dynamics in the study population. Similar results
were reported by Abdi et al.[26]

Our findings revealed no significant association
between asthenopia and phoria. Kaufmann et al[27]
reported that it was difficult to draw a causal rela-
tionship between phoria and asthenopia for three

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Asthenopia among University Students; Hashemi et al

Table 3. Simple and multi-variable logistic regression for the associated risk factors of asthenopia

OR Unadjusted 95% CI P-Value OR Adjusted 95% CI P-Value

Sex

Female 1.44 1.01–2.05 0.041

Male Reference

Age group (year)

18–19 1.85 0.85–4.02 0.111 1.66 0.73–3.77 0.203

20–21 1.68 0.89–3.18 0.101 1.68 0.78–3.65 0.167

22–23 1.79 1.03–3.13 0.042 1.69 0.87–3.29 0.108

24–25 1.89 0.90–3.96 0.085 1.89 0.83–4.31 0.116

26–27 2.17 0.90–5.20 0.077 2.06 0.93–4.55 0.071

28–29 3.15 1.40–7.07 0.01 3.51 1.26–9.89 0.021

≥ 30 Reference Reference
Refractive error

Emmetropia Reference

Myopia 1.58 1.27–1.98 0.001

Hyperopia 1.89 0.38–9.35 0.394

Astigmatism

No Reference Reference

Yes 1.6 1.24–2.06 0.002 1.61 1.22–2.13 0.003

BMI

Normal Reference

Underweight 1.1 0.71–1.72 0.617

Overweight 1.08 079–1.48 0.584

Semester

1–4(≤ 2 year) Reference
> 4(> 2 year) 0.9 0.69–1.17 0.418

Anisometropia

No Reference

Yes 1.58 0.584.14 0.337

Near Phoria

No Reference

Eso 1.06 0.79–1.42 0.671

Exo 2.76 0.98–7.75 0.054

Hyper 0.56 0.12–2.66 0.427

AA (diopter) 0.95 0.92–0.98 0.007

NPC (cm) 0.91 0.87–0.96 < 0.002  0.91  0.86–0.97  0.008

AA, accommodative amplitude; BMI, body mass index; NPC, near point of convergence; OR, odds ratio

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Asthenopia among University Students; Hashemi et al

reasons: lack of objective criteria for detecting
asthenopia, non-recognition of the pathogenetic
mechanism of the effect of phoria on asthenopia,
and the presence of other conditions with sim-
ilar symptoms such as dry eye, accommodative
anomalies, and aniseikonia.

Results obtained from most studies suggest
that prolonged computer work is an important
risk factor in the development of asthenopia.
For instance, Han et al[5] reported that the odds
of asthenopia were 21% higher in students who
worked on computer every day as compared with
those without daily use of computer. Moreover, it
has been reported that computer work for 6 h a
day or 30 h a week has a strong association with
asthenopia.

One of the limitations of this study was that
we did not evaluate near work duration, which
we plan to consider in future studies. Moreover,
the possible organic causes of asthenopia were
not assessed. Although exophoria is a well-known
determinant of asthenopia, its effect was not signifi-
cant in our study, probably owing to the low number
of participants suffering from this type of phoria.

In conclusion, the present study demonstrated
for the first time a high prevalence of asthenopia
in Iranian university students above 18 years as
compared with the results of other similar studies,
including those on subjects below 18 years.

Financial Support and Sponsorship

This project was supported by Mashhad University
of Medical Sciences.

Conflicts of Interest

There is no conflict of interest.

REFERENCES

1. Bhanderi DJ, Choudhary S, Doshi VG. A community-
based study of asthenopia in computer operators. Indian
J Ophthalmol 2008;56:51–55.

2. Garcia-Munoz A, Carbonell-Bonete S, Cacho-Martinez P.
Symptomatology associated with accommodative and
binocular vision anomalies. J Optom 2014;7:178–192.

3. Ayanniyi AA, Folorunso FN, Adepoju FG. Refractive ocu-
lar conditions and reasons for spectacles renewal in a
resource-limited economy. BMC Ophthalmol 2010;10:12.

4. Vilela MA, Pellanda LC, Fassa AG, Castagno VD. Preva-
lence of asthenopia in children: a systematic review with

meta-analysis. J Pediatr (Rio J) 2015;91:320–325.
5. Han CC, Liu R, Liu RR, Zhu ZH, Yu RB, Ma L. Prevalence of

asthenopia and its risk factors in Chinese college students.
Int J Ophthalmol 2013;6:718–722.

6. Wajuihian SO. Frequency of asthenopia and its association
with refractive errors. Afr Vis Eye Health 2015;74:74–80.

7. Wiggins NP, Daum KM. Visual discomfort and astig-
matic refractive errors in VDT use. J Am Optom Assoc
1991;62:680–684.

8. Mocci F, Serra A, Corrias GA. Psychological factors and
visual fatigue in working with video display terminals.
Occup Environ Med 2001;58:267–271.

9. Sanchez-Roman FR, Perez-Lucio C, Juarez-Ruiz C, Velez-
Zamora NM, Jimenez-Villarruel M. [Risk factors for
asthenopia among computer terminal operators]. Salud
Publica Mex 1996;38:189–196.

10. Agarwal S, Goel D, Sharma A. Evaluation of the factors
which contribute to the ocular complaints in computer
users. J Clin Diagn Res 2013;7:331–335.

11. Ostrovsky A, Ribak J, Pereg A, Gaton D. Effects of job-
related stress and burnout on asthenopia among high-tech
workers. Ergonomics 2012;55:854-862.

12. WHO Expert Consultation. Appropriate body mass index
for Asian populations and its implications for policy and
intervention strategies. Lancet 2004;363:157–163.

13. Vertinsky T, Forster B. Prevalence of eye strain among
radiologists: influence of viewing variables on symptoms.
AJR Am J Roentgenol 2005;184:681–686.

14. Hashemi H, Khabazkhoob M, Forouzesh S, Nabovati
P, Yekta AA, Ostadimoghaddam H. The prevalence of
asthenopia and its determinants among schoolchildren. J
Compr Pediatrics 2017;8:e43208.

15. Rocha LE, Debert-Ribeiro M. Working conditions, visual
fatigue, and mental health among systems analysts in Sao
Paulo, Brazil. Occup Environ Med 2004;61:24–32.

16. Ahmed F. Headache disorders: differentiating and manag-
ing the common subtypes. Br J Pain 2012;6:124–132.

17. Mvitu MM, Kaimbo WK. [Manifestations of asthenopia in
Black subjects]. Bull Soc Belge Ophtalmol 2003;289:45–
49.

18. Digre KB, Brennan KC. Shedding light on photophobia. J
Neuroophthalmol 2012;32:68–81.

19. Abdi S, Lennerstrand G, Pansell T, Rydberg A.
Orthoptic findings and asthenopia in a population of
Swedish schoolchildren aged 6 to 16 years. Strabismus
2008;16:47–55.

20. Shima M, Nitta Y, Iwasaki A, Adachi M. [Investigation
of subjective symptoms among visual display terminal
users and their affecting factors–analysis using log-linear
models]. Nihon Eiseigaku Zasshi 1993;47:1032–1040.

21. Stevens GA, White RA, Flaxman SR, Price H. Global
prevalence of vision impairment and blindness: magni-
tude and temporal trends, 1990–2010. Ophthalmology
2013;120:2377–2384.

22. Hashemi H, Khabazkhoob M, Yazdani N, Ostadimoghad-
dam H, Derakhshan A, Soroush S, et al. The prevalence of
refractive errors among Iranian University students. Iran J
Ophthalmol 2014;26:129–135.

23. Schellini S, Ferraz F, Opromolla P, Oliveira L, Padovani C.
Main visual symptoms associated to refractive errors and

JOURNAL OF OPHTHALMIC AND VISION RESEARCH Volume 14, Issue 4, October-December 2019 481



Asthenopia among University Students; Hashemi et al

spectacle need in a Brazilian population. Int J Ophthalmol
2016;9:1657–1662.

24. Daum KM, Good G, Tijerina L. Symptoms in video display
terminal operators and the presence of small refractive
errors. J Am Optom Assoc 1988;59:691–697.

25. Kotegawa Y, Hara N, Ono K, Arimoto A, Mukuno K. [Influ-
ence of accommodative response and visual symptoms
on visual display terminal adult operators with asthenopia

through adequately corrected refractive errors]. Nippon
Ganka Gakkai Zasshi 2008;112:376–381.

26. Abdi S, Rydberg A. Asthenopia in schoolchildren, orthoptic
and ophthalmological findings and treatment. Doc Oph-
thalmol 2005;111:65–72.

27. Kaufmann H, H. S. Heterophorie und Asthenopie. In:
Ru¨ssmann WGK, editors. Strabismus: Thieme;2012:119–
221.

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