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   Table of Contents      
Year : 2021  |  Volume : 69  |  Issue : 1  |  Page : 140-144

Prevalence and risk factor assessment of digital eye strain among children using online e-learning during the COVID-19 pandemic: Digital eye strain among kids (DESK study-1)

Department of Pediatric Ophthalmology and Strabismus, Children Eye Care Center, Sadguru Netra Chikitsalya and Postgraduate Institute of Ophthalmology, Chitrakoot, Madhya Pradesh, India

Date of Submission05-Aug-2020
Date of Acceptance15-Oct-2020
Date of Web Publication15-Dec-2020

Correspondence Address:
Dr. Amit Mohan
Children Eye Care Center, Department of Pediatric Ophthalmology and Strabismus, Sadguru Netra Chikitsalya and Postgraduate Institute of Ophthalmology, Jankikund, Chitrakoot . 210204, Madhya Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijo.IJO_2535_20

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Purpose: The aim of this study was to determine prevalence, symptoms frequency and associated risk factors of digital eye strain (DES) among children attending online classes during COVID-19 pandemic. Methods: The online electronic survey form was prepared on the Google app. Children/parents were asked to indicate the total duration of digital device use before and during COVID era. The symptoms of DES, its severity and frequency were recorded & measured with the Computer Vision Syndrome Questionnaire. Results: Two hundred and sixty one parents responded to the questionnaire, of these 217 were complete. Mean age of children was 13 ± 2.45 years. Mean duration of digital device used during COVID era was 3.9 ± 1.9 h which is more than pre COVID era (1.9 ± 1.1 h, P = <0.0001). 36.9% (n = 80) were using digital devices >5 h in COVID era as compared to 1.8% (n = 4) before COVID era. The most common digital device used were smartphones (n = 134, 61.7%). One hundred and eight children (49.8%) were attending online classes for >2 h per day. Prevalence of DES in our cohort is 50.23% (109/217). Of these 26.3% were mild, 12.9% moderate and 11.1% of severe grade. Most common symptoms were itching and headache (n = 117, 53.9%). Multivariate analysis revealed age >14 years (P = 0.04), male gender (P = 0.0004), smartphone use (P = 0.003), use of device >5 h (P = 0.0007) and mobile games >1 h/day (P = 0.0001) as independent risk factors for DES in children. Conclusion: There is an increased prevalence of DES among children in COVID era. Parents should be considerate about duration, type and distance of digital device use to avoid DES symptoms in children.

Keywords: Digital eye strain, Children, computer vision syndrome, COVID pandemic, online classes and e-learning

How to cite this article:
Mohan A, Sen P, Shah C, Jain E, Jain S. Prevalence and risk factor assessment of digital eye strain among children using online e-learning during the COVID-19 pandemic: Digital eye strain among kids (DESK study-1). Indian J Ophthalmol 2021;69:140-4

How to cite this URL:
Mohan A, Sen P, Shah C, Jain E, Jain S. Prevalence and risk factor assessment of digital eye strain among children using online e-learning during the COVID-19 pandemic: Digital eye strain among kids (DESK study-1). Indian J Ophthalmol [serial online] 2021 [cited 2023 May 29];69:140-4. Available from: https://journals.lww.com/ijo/pages/default.aspx/text.asp?2021/69/1/140/303306

Educational institutions in the country have been closed since March, 2020 to halt the spread of the novel coronavirus disease (COVID). However, there is uncertainty as to when these schools will reopen. Since there is no immediate solution to stop the spread of the COVID pandemic, the closure of schools will continue, having a large effect on the learning of children. The outbreak has changed the traditional teaching method of using black boards to digital device-assisted online classes.[1]

This means that an extra time of sitting in front of a digital device will be required for this new e-learning system. Spending long hours in front of these devices can lead to many ocular problems in children. Digital eye strain (DES) is the most common eye problem associated with prolonged digital device use, characterized by symptoms such as dry eyes, itching, foreign body sensation, watering, blurring of vision, and headaches.[2]

The prevalence of digital eye strain is estimated to range from 25% to 93%, as reported in various studies.[3],[4],[5] Reddy et al. reported DES in 89.9% of students in their questionnaire-based study.[5] Higher prevalence rates of DES were observed in adolescents using smartphones or in those who were regularly and excessively using digital devices (>2 h daily and continuously).[6]

Although the ocular complications of digital device use have been extensively studied in adolescents and young adults, only a few studies have addressed DES in children.[7],[8] Ocular symptoms and DES related to the excessive use of digital devices due to the increased duration of online classes in this COVID era have been discussed extensively in the media, but have not been properly studied and reported in the literature.

This study aimed to determine the prevalence, symptom frequency, and associated risk factors of DES among children of higher secondary schools who use digital devices to attend online classes during the COVID-19 pandemic.

  Methods Top

This was a questionnaire-based cross-sectional study analyzing DES among higher secondary school children who are attending online classes during the COVID-19 pandemic. An online survey questionnaire was developed by the authors, which comprised of 4 sections: demography of the children, digital device information, DES symptoms questionnaire, and good ocular health safety tips for children during digital device use. Before recruitment, participants were informed about the purpose, length, and anonymity of the study. The parents were also informed that their data would be used for research purposes, but without disclosing the identity of the participants. The study was conducted in accordance with the Declaration of Helsinki, and was approved by the appropriate Institutional Review Board.

The children or their parents were asked to indicate the average time in hours per day spent on each of the following activities: computer/PAD use, smartphone use, online classes, watching TV, and playing of video games during the COVID era as well as the total duration of digital device use before and during the COVID era. DES symptoms and their severity and frequency were recorded. The online electronic survey [Annexure 1][Additional file 1] form was prepared on the Google survey forms app. The survey was circulated as a google link among social media groups of parents and was open to responses for one week in July after the lockdown in India. The DES symptoms and its severity were measured using the Computer Vision Syndrome Questionnaire (CVS-Q) developed by Segui et al.[9] The CVS-Q evaluated the intensity (moderate or intense) and frequency (never, occasionally, or always/often) of 16 eye strain-related symptoms, including burning sensation, itching in the eyes, foreign body sensation, watering, excessive blinking, redness, eye pain, heaviness in the eyelids, dryness, blurring of vision, double vision, difficulty in near vision, intolerance to light, colored halos, worsening of vision, and headache. Frequency was recorded as follows: NEVER = symptoms did not occur at all; OCCASIONALLY = sporadic symptoms or once a week; OFTEN OR ALWAYS = 2 or 3 times in a week or almost daily. Intensity was recorded as MODERATE or SEVERE.

The total score was calculated by applying the following formula:

Score (frequency of symptom occurrence)i

(intensity of symptom)i

[Where Frequency: Never = 0, Occasionally = 1, Often or always = 2 & Intensity: Moderate = 1, Intense = 2].

The overall assessment was conducted by obtaining the total score, recorded as the DES score. The result of frequency X intensity was recorded as: 0 = 0; 1 or 2 = 1; 4 = 2. If the total score was ≥6 points, the child was considered to be suffering from digital eye strain. DES scores were further categorized as mild (DES score = 6-12), moderate (DES score = 13-18), and severe (DES score = 19-32).

All the data that was collected from the respondents were exported as Microsoft Excel sheets from the Google drive link, and statistical analysis was performed using the IBM SPSS Statistics software. Quantitative variables were presented as mean ± standard deviation, while qualitative variables were presented as numbers and percentages.

The associated risk factors of DES were analyzed by univariate and multivariate logistic regression with age, gender, device used (smartphone, desktop, laptop/tab), viewing distance, and duration of screen use. In the univariate analysis, the Chi-square or Fisher's exact test was used to investigate the associations between the qualitative variables. In the multivariate analysis, multiple logistic regression analysis was performed to identify the independent risk factors for DES by calculating the odds ratios (ORs) and their corresponding 95% CI. A P value <0.05 was considered statistically significant.

  Results Top

A total of 261 parents/guardians responded to the questionnaire within the set time frame. Of these, we included in our study analysis the 217 participants who provided complete responses to the survey. The mean age of the children was 13 ± 2.45 years, of whom 101 (46.54%) were males. Of the respondents, 56.2% were students in the 6th to 8th standard (n = 122). In addition, 96.3% (n = 209) of the children were attending online classes. The mean duration of digital device use during the COVID era was 3.9 ± 1.9 h, which was longer than that in the pre-COVID era (1.9 ± 1.1 h, P = <0.0001). Furthermore, 36.9% (n = 80) of children were using digital devices for >5 h in the COVID era as compared to 1.8% (n = 4) of children before the COVID era. The most common digital devices used were smartphones (n = 134, 61.7%) for online classes, and 108 children (49.8%) were attending online classes for >2 h per day. In total, 31.6% (n = 66) of children used digital devices at <18 inches from the eyes during the online classes. [Table 1] shows the demographic and digital device use details as per the responses submitted by the parents.
Table 1: Demographic characteristics and details of digital device usage

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The most common symptoms associated with DES in our study were itching (n = 117, 53.9%) and headache (n = 117, 53.9%). Double vision (n = 24, 11.1%) and seeing halos around objects (n = 44, 20.27%) were the least common presenting symptoms. In total, 49.76% of parents (n = 108) thought that their children's eyesight worsened because of the online classes. [Figure 1] shows the number of children affected by the different CVS-Q symptoms with the frequency and severity.
Figure 1: Number of children affected by different symptoms of digital eye strain with their frequency and severity

Click here to view

The prevalence of DES in our cohort was 50.23% (109/217). Of these, 26.3% were of mild grade (n = 57), 12.9% of moderate grade (n = 28), and 11.1% of severe grade (n = 24) DES scores. [Figure 2] shows the percentage of children with the different DES grades.
Figure 2: Percentage of children with the different grades of digital eye strain

Click here to view

DES was significantly associated with male gender (P < 0.0001, odds ratio-1.59), smartphone use (P = 0.01, odds ratio-1.98), duration of digital device use >5 h (P < 0.0001, odds ratio-3.38), digital device distance <18 inches (P = 0.09, odds ratio-1.65), and use of mobile games >1 h per day (P < 0.0001, odds ratio-16.69) in univariate analysis.

As shown in [Table 2], the multivariate analysis revealed that age >14 years (P = 0.04), male sex (P = 0.0004), smartphone preference over other digital devices (P = 0.003), use of digital devices >5 h (P = 0.0007), and use of mobile games >1 h/day (P = 0.0001) were independent risk factors for DES in children.
Table 2: Multivariate logistic regression analysis of risk factors associated with digital eye strain

Click here to view

  Discussion Top

Due to the spreading of the COVID-19 pandemic worldwide, many states or central governments have decided to close schools in order to maintain social distancing, as means of halting the transmission of this deadly virus. However, the closure of schools has affected the education of more than 1.5 billion children and youths worldwide.[10] In India, 41% of the population belong to <18 years age group. The mean age of the participants in our study was 13 ± 2.45 years (range 10-18 years), which is representative of this major population.

School closure protects children from COVID, but this affects their education. To avoid this, educational institutions around the globe are shifting to the online teaching—e-learning method. Digital learning has become a daily necessity during this Covid-19 pandemic, leading to a marked increase in digital device use among children of school-going age. In our study, 96.3% of the children were attending online classes for e-learning. A European study reported that 68% of children regularly used computers and 54% undertook online activities.[11] Most of the children in our study were students in the class 6th to 8th standard. The average time spent in front of digital devices in our study was 3.9 ± 1.9 (range 1–9) h, which is similar to a study done in the UK, in which the participants spent approximately 4 h per day on digital devices.[11] In a study conducted in rural western India, they reported that the average time spent in front of a screen among children was approximately 2.7 ± 1.7 h,[12] which is less than our cohort. In our study, 36.9% of children spent >5 h on digital devices, which is similar to the pattern of a study conducted by Badri et al., who reported that the average time spent on social media by students was 5.2 h per day.[13]

In our study, the most common device used for online classes was the smartphone (61.7%). Previous studies suggest that older age groups prefer using laptops and desktops to browse the internet, whereas younger adults/children are more likely to use smartphones for this purpose,[2],[14] similar to our study. As reported by Shepard et al., 87% of individuals use two or more digital devices simultaneously for multiple tasks[2]; however, only 20.3% of children used multiple devices for online classes in our study.

DES constitutes a range of visual symptoms; its prevalence may be 50% or more among computer users.[15] In our study, the prevalence of DES was also found to be 50.23%. However, a recent meta-analysis reported that the pooled prevalence of DES is 19.7% in children.[7] In a study conducted in the private schools of west India, they reported the prevalence of DES as 17.9%.[16] The increased prevalence of DES in our study is probably due to the increased visual demand of digital device use in our cohort because of the online classes in this COVID era. There was a significant increase in the mean duration of digital device use during the COVID era (3.9 ± 1.9 h) compared to the pre-COVID era (1.9 ± 1.1 h, P = <0.0001). In the COVID era, 36.9% of children were using digital devices for >5 h compared to 1.8% of children before the COVID era. This is probably the main reason for the increased prevalence of DES in our survey. In this study, 96.3% of children were attending online classes, out of which 49.8% of them were attending online classes for >2 h per day. In a study conducted in India before the COVID era, only 40% of children were using smartphones for school project purposes, and only 3.3% spent >5 h per day on digital devices.[15] In addition, 68.4% of children were using digital devices at a distance of >18 inches, which is similar to the study carried out by Ichapujani et al.[16] in which 56% were maintaining an ideal distance for digital device use.

Portello et al.[3] categorized the DES symptoms into two groups: 1) symptoms related to accommodation (blurred vision for near objects, headache, and eyestrain) and 2) symptoms related to dryness (burning sensation, foreign body sensation, itching, watering, intolerance to light). We also analyzed the DES symptoms using a validated questionnaire developed by Seguì et al.[9] The self-administered CVS-Q requires participants to report the intensity and frequency of 16 symptoms experienced during digital device use, where a cumulative score of six or more is considered as diagnostic of DES. The CVS-Q is a pretested, verified, and validated tool used to diagnose DES.[9] The most common symptoms reported in our study were itching and headache in 53.9% of cases. Headache, burning sensation, and tired eyes are common visual-related problems associated with DES. The most common symptoms reported by Shantkumari et al. among school children using digital devices were headache and burning sensation in 53.3% and 54.8% of cases, respectively.[17]

Multivariate analysis of current study revealed age >14 years, male sex, smartphone preference over other digital devices, use of digital devices >5 h, and use of mobile games >1 h/day were found to be independent risk factors for DES in children.

DES symptoms were reported to be more common in females; however, in our study, the male sex appeared to be at higher risk (P < 0.0001, odds ratio-1.59). Visual symptom scores in digital device users were found to be higher among females than males in a study done by Shima et al.[18] The results of our study indicate that male children are involved in multitasks on digital devices, making them to be at increased risk.

An advancing age of >14 years was also found to be a higher risk factor for DES in our study. Moon et al. also reported that symptoms of dry eye diseases were higher in the children of the older age group than in the younger age group. Children of a higher age were spending more hours on smartphone use, which may lead to a higher DES prevalence in older children.[19] There was a longer duration of online classes in higher grades than in the lower grades.

Smartphone preference over other digital devices was found to be an independent risk factor for DES among the children in our study. Continuous smartphone use leads to a decrease in the blink rate, causing dry eye-related problems. Smartphones are also used with a short viewing distance because of their small screens, thus causing more asthenopia symptoms. Moon et al. also reported that smartphone use was more commonly associated with dry eye disease (71%, P = 0.036) as compared to other digital devices in a case-control study among school-going children.[20]

Duration in front of a screen of >5 h was found to be a significant risk factor for higher DES scores in our study, which is a well-known factor for asthenopia among digital device users. A study reported that the prevalence of DES was significantly higher in individuals who spent >4 h per day on digital devices.[16] Similar results were found in another study, which reported that the duration in front of a screen was directly proportional to the DES symptoms.[21] Shortening the duration of digital device use has a great effect on the symptoms of DES. The 20/20/20 rule has been suggested to minimize asthenopia symptoms during computer use. After every 20 minutes of digital device use, look at a distance of 20 feet for at least 20 seconds.[22]

During this COVID pandemic, there are restrictions on outdoor activities for children, which has led to an increase in the time spent by these children to play videogames on smartphones. Most children play videogames for long hours with maximum concentration and without any break; this can cause a newly described condition in children known as videogame vision syndrome.[23] Prolonged activity on smartphones while playing videogames can lead to DES and accommodative problems in children. In our study, the use of mobile games for >1 h per day was a significant risk factor for DES among children in multivariate analysis (P = 0.0001). The prolonged and constant use of smartphone-based video games in children may have an adverse effect on their visual system and cause DES.[24]

A shorter screen distance has been associated with a higher risk of DES in children in some studies.[17],[25] An increased incidence of eyestrain was reported by Shantakumari et al.[17] in their study of students who watched computer screens at a distance of <50 cm. This may be due to the disparity between the screen viewing distance and the individual's convergence.[26] However, in the current study, there was no significant association between screen distance and DES among the children in the multivariate analysis, but in univariate analysis, the association was near to significance (P = 0.06). This might be due to the response error because of the approximate reply without actual measurement of the digital device distance from the eyes. Bilton[27] described the one-two-ten (1, 2, 10) rule for the distances for digital devices: mobile phones at a distance of one foot; desktops and laptops at a distance of two feet; and television at a distance of 10 feet. The American Academy of Ophthalmology recommends a minimum distance of approximately 25 inches (about an arm's length) from the screen when using a computer.[28]

The purpose of our survey was to collect data on DES and to make the guardians and children aware of good ocular health habits and tips in order to avoid DES. We have added a section on good ocular hygiene and practices during digital device use in our questionnaire and insisted that the participants should practice the recommendations. Children should be encouraged to blink when reading text on screens. Avoid keeping the device close to the eyes, monitor screen time, and include a healthy diet rich in carotenoids and green leafy vegetables. Adequate sleep is necessary. Regular eye check-ups are strongly recommended.

In future studies, we will analyze the impact of good ocular health habits on DES scores.

Our study had a few limitations. Although this survey was circulated in parents' social media groups, we were unable to identify whether all the responders were parents/guardians of school-going children. In addition, our study was designed on a symptom-based questionnaire that requires responders to indicate the frequency and intensity of symptoms experienced during digital device use, which is a subjective feeling and varies from person to person, and may have recall bias. We have also not considered refractive error of children in account as it was not the part of our questionnaire.

  Conclusion Top

Our study highlights the higher prevalence of DES among children in the present scenario of the COVID pandemic and the effect of the e-learning teaching model on children's ocular health. Our findings highlight an important child ocular health issue in this era and make the parents, teachers, and eye care providers to be considerate about evidence-based measures to avoid DES in children.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

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  [Figure 1], [Figure 2]

  [Table 1], [Table 2]

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76 Commentary: Online school in COVID-19 pandemic: Impact on lifestyle and ocular health
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77 Impact of the use of digital devices on eyes during the lockdown period of COVID-19 pandemic
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78 Magnitude and determinants of computer vision syndrome among college students at a Saudi University
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