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 Table of Contents  
Year : 2021  |  Volume : 33  |  Issue : 3  |  Page : 284-290

Digital eye strain among undergraduate medical students during the COVID-19 pandemic: A cross-sectional survey

Department of Ophthalmology, Government Medical College, Kozhikode, Kerala, India

Date of Submission24-Oct-2020
Date of Decision13-Nov-2020
Date of Acceptance13-Nov-2020
Date of Web Publication08-Dec-2021

Correspondence Address:
Dr. Ferzana Mohammed
Department of Ophthalmology, Government Medical College, Kozhikode - 673 008, Kerala
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/kjo.kjo_168_20

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Background and Objective of the Study: The COVID-19 pandemic has increased the use of online platforms for education. This may lead to digital eye strain (DES) in the student community. The objective of this study was to assess the pattern of digital device use, the prevalence of DES symptoms and assess the awareness of DES among undergraduate medical students. Materials and Methods: This was a cross-sectional study and was conducted among undergraduate medical students of a medical college in Kerala using a structured, self-administered online questionnaire. Results: Two-hundred and twenty-seven students responded to this questionnaire. Of these respondents, 90.3% (205 students) reported experiencing the ocular and extra-ocular symptoms of DES. Neck pain, headache, and watering of eyes were the most frequent symptoms. Continuous use of devices without breaks, the predominant activity on devices, the presence of refractive errors, and inappropriate control of glare on digital devices had a statistically significant association with DES. Although 79.4% of students were aware that using digital devices can cause eye strain, <20% were aware of the ideal distance for viewing digital screens and the 20-20-20 rule of taking breaks in-between screen time. Conclusion: Undergraduate medical students reported a high prevalence of DES during the COVID-19 college shutdown. Lack of timely breaks and inappropriate control of glare from monitors were associated with DES symptoms. Only a few students were aware of the ergonomic measures to be adopted during device use. Educating undergraduate medical students about DES is essential to curb this rising problem.

Keywords: Asthenopia, computer vision syndrome, digital eye strain, gadget use

How to cite this article:
Mohammed F, Somasundaran S, Poothatta J. Digital eye strain among undergraduate medical students during the COVID-19 pandemic: A cross-sectional survey. Kerala J Ophthalmol 2021;33:284-90

How to cite this URL:
Mohammed F, Somasundaran S, Poothatta J. Digital eye strain among undergraduate medical students during the COVID-19 pandemic: A cross-sectional survey. Kerala J Ophthalmol [serial online] 2021 [cited 2022 Aug 8];33:284-90. Available from: http://www.kjophthal.com/text.asp?2021/33/3/284/331931

  Introduction Top

The COVID-19 pandemic has created new challenges in medical education worldwide.[1] Online lectures and clinical scenarios have replaced conventional teaching in the clinics and wards. Technology has enabled us to communicate and disseminate information, even during this challenging period. However, we must be aware of the ophthalmologic and psychosocial problems that may occur because of the unmitigated usage of digital devices.

Digital eye strain (DES) refers to the ocular and extra-ocular symptoms because of digital device use. The ocular symptoms of DES include asthenopic symptoms such as eyestrain, headache, tired eyes; vision-related symptoms such as blurred vision and double vision; ocular-surface-related symptoms such as watery eyes, burning sensation of the eyes, and redness of eyes. The extra-ocular symptoms include neck pain, back pain, and upper extremity pain.[2]

Utilizing good ergonomic practices can mitigate the symptoms of DES. These include using adequate illumination, adopting appropriate posture, taking frequent breaks and adjusting screen brightness, resolution, and font size.[3]

This study aims to survey the undergraduate medical students of a government medical college in North Kerala to assess the pattern of digital device use, the prevalence of the symptoms of digital eye-strain, and the awareness regarding DES.


  1. To evaluate the pattern of digital device usage among undergraduate medical students
  2. To estimate the prevalence of symptoms of DES among undergraduate medical students
  3. To assess the awareness among undergraduate medical students regarding DES and the practices to prevent it.

  Materials and Methods Top

Study design, study period, and setting

This was a cross-sectional questionnaire-based study done at a tertiary care teaching institute in Kerala. It was conducted from June to September 2020. This center has 1000 undergraduate medical students.

Sample size determination

The sample size was determined with the following assumptions: margin of error 5%, the proportion of DES 89.9%,[4] 95% confidence interval (CI), and population size of 1000 to come up with a sample size of 127 respondents.

Data collection method

A self-administered questionnaire was prepared based on the symptoms of DES identified in the current literature.[5],[6] An initial pilot on 5% of the sample was conducted. Based on posttest feedback, any leading or confusing questions were appropriately rephrased. It was then sent to the students through E-mail and circulated within student groups.

The questionnaire had three parts:

  1. The first part of the questionnaire had 13 items. The initial three items were on the socio-demographic characteristics. The next 10 items were on the pattern of digital device usage, including the device most frequently used, hours spent on technological devices per day, how frequently breaks are taken during electronic use, the eye-to-screen distance and the position in which devices are used
  2. The second part of the survey had nine questions. These were on the validated symptoms of DES (headache, dry eyes, burning eye sensation, eye redness, blurred vision, neck, and shoulder pain). The symptoms were graded as mild (transient symptoms for a few minutes to an hour), moderate (continues for hours and subsides after rest), or severe (needs medications)
  3. The third part of the questionnaire contained 11 questions. These were regarding the awareness of DES and pattern of device use among the undergraduate medical students.

The survey questionnaire is given as Supplementary Material 1.

Data processing and analysis

The data were analyzed using SPSS Statistics for Windows, version 18.0 (SPSS Inc., Chicago, Ill., USA). The descriptive data were presented as frequencies and percentages. Pearson's Chi-square test and odds ratio were used to measure the association between categorical study and outcome variables. For statistical significance and precision, we used a P < 0.05 and a 95% CI.

Ethical considerations

The ethical clearance was taken from the Institutional Review Board of the institution. Informed consent was sought from all the participants after describing the purpose of the study. All participants were informed of their right to withdraw at any time, without any obligation toward the study team. No incentives were offered to the study participants, and confidentiality of the data was maintained.

  Results Top

Demographics and digital device use pattern

Two-hundred and twenty-seven undergraduate medical students responded to the questionnaire. The age of the students ranged from 18 to 26 years, with a mean age of 21 years. Of the respondents, 134 were female (59%) and 93 males (41%). The smartphone was the most regularly used device by 216 students (95%). Six students reported spending the most time with tablets and five with laptops.

One hundred and sixty students (70%) reported spending over 6 h with digital devices, 50 (22%) spent between 4 and 6 h, and 17 (7%) spent between 2 and 4 h. Ninety-five students reported browsing social media to be their most frequent activity, 60 students (26%) used most of their screen time for watching movies or television shows, 36 students (15%) spend the most time on their devices for academic purposes. For 22 students (10%) gaming was the chief activity, and 14 students (6%) spent maximum time on gadgets for recreational reading.

The time spent by the students on technological devices for their academics varied from <2 h in 95 students (42%), 2–4 h in 85 students (37%) to over 4 h in 47 students (21%). The preferred device for studying was the smartphone in 57% of the students. The most common posture adopted by the students for device use was sitting upright with a bent back (87 students), followed by the supine position (76 students), upright position with straight back in 47 students and the least used was the prone position (17 students). One hundred and fifty-five students (68%) used their devices at nighttime with the lights switched off, while 57 students used multiple devices at the same time. One-hundred and forty-two students (62.5%) reported more than a four-hour increase in screen time after the COVID-19 college shutdown [Figure 1].
Figure 1: Effect of the COVID-19 induced college shutdown on electronic device use among medical students

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Digital eye strain symptoms

The symptoms of DES were present in 205 of the 227 students who had participated in this study. Thus, the self-reported prevalence of DES among undergraduate medical students was 90.3% (95% CI-86.3, 94.3). The most common symptoms were neck pain (128 students), headache (125 students), and watering of eyes (97 students). Seventy-eight students had a backache, 72 had itchy eyes, 65 students had burning sensation of eyes, while 48 experienced redness of the eyes.

Digital exposure and digital eye strain

All the symptoms of DES investigated in this study showed a proportional relationship with the continuous use of electronic gadgets for over ½ h. However, only blurred vision, burning sensation of eyes and back pain reached levels of statistical significance. Further, using gadgets for over 4 h/day had greater odds of developing asthenopic and musculoskeletal symptoms, but this was not statistically significant [Table 1]. Regarding primary activity on digital devices, social media browsing (95.8%) and gaming (95.5%) showed the highest prevalence of DES symptoms. This was statistically significant (χ2 = 11.33, df = 4, P = 0.047).
Table 1: Symptoms of digital eye strain and digital exposure time

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Refractive error

Blurred vision after using electronic devices was seen more frequently in those with refractive errors (35.4%) than those without refractive errors (18%). This was statistically significant (odds ratio [OR]-2.6, 95% CI-1.42–4.80, P = 0.03). Among those with refractive error, we found a higher prevalence of blurred vision after gadget use those with myopia and astigmatism. This was also statistically significant (χ2 = 13.39, P = 0.01).

Digital eye strain and ergonomic factors

Of the 228 students, 128 students (56.4%) developed neck pain, 78 students had back pain (34.4%), and 53 students (23.35%) developed wrist or finger stiffness after digital device use. We analyzed the prevalence of musculoskeletal symptoms among the students with regard to the predominant posture adopted by them. Neck pain was most in those who primarily used devices in prone position and back pain in those who sat upright with a bent back.

The prevalence of DES symptoms among those who kept their smartphones less than arm's length away was 91.9%, those who kept a distance of an arms-length-88.2% and those who kept devices more than arm's length away was 85.7%. This was not statistically significant. There was also no statistically significant correlation between DES symptoms and the device primarily used, using electronic displays in the dark and using multiple devices simultaneously.

Awareness regarding digital eye strain

Out of the 228 medical students, 181 (79.4%) were aware that using digital devices can cause DES. Of these, 102 (44.9%) knew about the symptoms of DES. Eighty-six students (37.7%) had heard about the harmful effects of blue light emitted from electronic visual displays. Only 34 students (14.9%) knew about the ideal working distance for the use of electronic devices and 26 students (11.4%) had heard of the 20-20-20 rule. One hundred and sixty-five students (72.6%) used applications to control glare. The odds of developing burning sensation and itching were lower among the group utilizing applications for reducing glare (OR = 0.53, 95% CI-0.28–0.97, P = 0.04).

More female students had heard the term DES (62.8%) and this was statistically significant (χ2 = 5.05, P = 0.02). However, awareness about the symptoms of DES did not vary with gender. The awareness of the term DES, its symptoms and the awareness of the proper working distance of various devices and the 20-20-20 rule varied with the year of study [Table 2].
Table 2: Level of awareness among undergraduate medical students classified according to the year of study

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  Discussion Top

This study explored the pattern of digital device use, the prevalence of DES, symptoms of DES and the knowledge, attitude, and practices regarding DES among undergraduate medical students during the COVID-19 college shutdown.

The prevalence of DES among the students was 89.9%. This is close to the other similar studies in the literature [Table 3]. The most frequent symptoms encountered in this study was neck pain and headache. Sanodiya et al., Abudawood et al., Logaraj et al. and Reddy et al. found neck pain to be most common, while Al Tawil et al. and Mowatt et al. reported headache as the most common symptom.[4],[7],[8],[10],[11],[13]
Table 3: Prevalence of digital eye strain and its symptoms in literature

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Asthenopic symptoms

Headaches and tired eyes are a significant cause of interruption to the work of the students.[12] In our study, 21.6% of students had moderate-to-severe headache following digital device use. The reason for asthenopic symptoms following gadget use may be because of (1) changes in the accommodation (increased lag and decreased amplitude) and (2) changes in the vergence (receding of near point of convergence and decreased positive and negative fusional vergence.[14]

Refractive error and digital eye strain

In this study, there was a statistically significant association between refractive error and blurred vision after prolonged gadget use. Bhanderi et al. and Nakaishi and Yamada had noted more asthenopic symptoms after gadget use in those with corrected refractive errors.[15],[16] We found that myopia and astigmatism had a higher degree of eye strain. Schellini et al. and Hashemi et al. have reported higher gadget-use-related asthenopia in those with astigmatism and myopia.[17],[18] This may be because of the increased accommodative effort in placing the circle of least confusion on the retina in astigmatism. Since the number of hypermetropes in this study was low compared to myopes, larger studies are needed to establish whether myopes experience more DES symptoms.

Dry eye symptoms

We found statistically significant higher odds of developing burning sensation of the eyes on using devices continuously for over 30 min without breaks. Several studies have reported dry eye symptoms after continuous gadget use. The reason for this may be the reduced blink rate.[19],[20] Again, the decreased blink rate may be due to involuntary eyelid squinting, which helps in improving visual acuity and reducing retinal illumination.[21],[22] Another reason for dry eyes may be the higher percentage of incomplete blinks.[23] This study also found a significantly lower prevalence of burning sensation among those who used applications to control glare on their screens (P = 0.04). This highlights that even simple measures such as adjusting the display brightness can help reduce DES.

Musculoskeletal symptoms

A survey by Hupert et al. in college students reported a 42% prevalence of computer-associated upper extremity musculoskeletal symptoms.[24] Our respondents also reported a high prevalence of neck, back and wrist pain or stiffness following electronic device use. These symptoms were highest in those who used devices in the prone position and on using devices in an upright position with a bend back. As opined by Toh et al., the use of touch-screen on mobiles and their portability leads to unconventional postures and greater musculoskeletal stress, even more than conventional visual display terminal use. This manifests as neck, shoulder, and wrist and finger stiffness.[25]

Digital exposure and eye strain

Many studies have reported associations between both total hours of digital exposure and continuous digital usage [Table 4]. In the present study, the use of devices for over 4 h a day had higher odds of developing DES symptoms; however, this was not statistically significant. The symptoms of blurred vision, burning sensation and back pain had a statistically significant relationship with continuous device use for over 30 min without breaks. We had also assessed the awareness of the 20-20-20 rule (every 20 min spent looking at a screen, look away at an object 20 feet away for 20 s). Among the medical students surveyed in this study, only 11% were aware of this rule, suggesting a lack of knowledge among the students regarding the appropriate timing and duration of the breaks to be taken during computer use.
Table 4: Digital exposure and eyestrain

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Other factors contributing to digital eye strain

In this study, browsing social media and gaming had the highest prevalence of DES symptoms. A study conducted by Masthi and Manasa among college students in Bengaluru found an increased eye strain and neck pain among social media users.[30] Studies have also reported a higher occurrence of asthenopic, dry eye, and musculoskeletal symptoms among gamers.[26] The high prevalence of DES symptoms in both these activities may be because of their addictive nature, leading to continuous use.

Using multiple devices at the same time is called dual or triple screening. Studies regarding the impact of dual screening on accommodation and convergence are scarce.[14] There is also a scarcity of data regarding the use of devices in the dark and DES symptoms. In this study, there was no association between dual screening, use of devices in the dark, and symptoms of DES.

Awareness of digital eye strain among undergraduate medical students

In this study, 79% of the students had heard of DES, though only 45% aware of the symptoms and about 11%–14% were aware of the proper ergonomic measures to be taken while using digital devices. Although the awareness regarding DES increased with the year of study, knowledge of the preventive measures was low, even among final-year medical students. These gaps in the knowledge maybe because of the low emphasis in the undergraduate ophthalmology curriculum on the management of DES.[31] Hence, this study also highlights the need for greater awareness among the medical community regarding the symptoms of DES and the ergonomic measures that need to be adopted while using digital devices.

  Conclusion Top

A significant number of undergraduate medical students suffer from symptoms of DES. Watering of eyes, headache, and neck pain were the most commonly encountered symptoms. Proper ergonomic measures are of paramount importance in preventing DES. However, only a few students were aware of these measures. Both the general ophthalmologist and ophthalmology teachers of medical schools should prioritize awareness activities regarding DES. This is especially important during this global COVID pandemic, where electronic device use has escalated.


This study was a self-administered, anonymous, opt-in survey. As the ophthalmic examination was not performed, the accuracy of the information submitted could not be verified. Furthermore, this study was confined to a single institution and so the discussion and interpretation may not be applicable to the general population of medical students.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  Supplementary Material 1 Top

Digital eye strain survey

1. How old are you?

2. What is your gender?

  1. Male
  2. Female.

3. Which year of medical education are you in?

  1. First year
  2. Second year
  3. Third year
  4. Fourth year
  5. Final year

4. Which digital device do you use the most?

  1. Smartphone
  2. Tablet
  3. Laptop
  4. Desktop computer
  5. Television

5. Which is your second most commonly used device?

  1. Smartphone
  2. Tablet
  3. Laptop
  4. Desktop computer
  5. Television

6. How much time per day do you spend on digital devices?

  1. Less than 2 h
  2. 2–4 h
  3. 4–6 h
  4. More than 6 h

7. On what activity do you spend the maximum time on your digital devices?

  1. Watching movies
  2. Studying
  3. Recreational reading
  4. Social media
  5. Playing games.

8. How much time do you spend on your favorite activity on your digital device?

  1. Less than 2 h
  2. 2–4 h
  3. 4–6 h
  4. More than 6 h

9. Which is your preferred device for studying?

  1. Smartphone
  2. Tablet
  3. Laptop
  4. Desktop computer

10. How many hours per day do you currently spend on digital devices for your academic activities?

  1. Less than 2 h
  2. 2–4 h
  3. More than 4 h.

11. Which is your most commonly used posture while using your smartphone?

  1. Upright with bend back
  2. Upright with straight back
  3. Lying down in supine position
  4. Lying down in prone position

12. At what working distance do you usually use your smartphone?

  1. Less than arm's length away
  2. About an arm's length away
  3. More than arm's length away

13. Approximately how long do you usually use any digital device at a stretch?

  1. 30 min
  2. 1 h
  3. 2 h
  4. More than 2 h

14. Do you experience any headache after prolonged use of digital devices?

  1. No
  2. Mild- persists for a few minutes to few hours
  3. Moderate - persists for hours and is relieved by rest or sleep
  4. Severe - requires the use of medications for relief

15. Are you experiencing any blurred vision after prolonged use of digital devices?

  1. No
  2. Mild- persists for a few minutes to few hours
  3. Moderate - persists for hours and is relieved by rest or sleep
  4. Severe - requires the use of medications for relief

16. Do you experience any watering of eyes after prolonged use of digital devices?

  1. No
  2. Mild- persists for a few minutes to few hours
  3. Moderate - persists for hours and is relieved by rest or sleep
  4. Severe - requires use of medications for relief

17. Do you experience any redness of eyes after prolonged use of digital devices?

  1. No
  2. Mild- persists for a few minutes to few hours
  3. Moderate - persists for hours and is relieved by rest or sleep
  4. Severe - requires the use of medications for relief

18. Do you experience any burning sensation of eyes after prolonged use of digital devices?

  1. No
  2. Mild- persists for a few minutes to few hours
  3. Moderate - persists for hours and is relieved by rest or sleep
  4. Severe - requires use of medications for relief

19. Do you experience any itching of eyes after prolonged use of digital devices?

  1. No
  2. Mild- persists for a few minutes to few hours
  3. Moderate - persists for hours and is relieved by rest or sleep
  4. Severe - requires the use of medications for relief

20. Do you experience any neck pain after prolonged digital device use?

  1. No
  2. Mild- persists for a few minutes to few hours
  3. Moderate - persists for hours and is relieved by rest or sleep
  4. Severe - requires the use of medications for relief

21. Do you experience any backache after prolonged digital device use?

  1. No
  2. Mild- persists for a few minutes to few hours
  3. Moderate - persists for hours and is relieved by rest or sleep
  4. Severe - requires use of medications for relief

22. Do you experience any wrist pain after prolonged smartphone use?

  1. No
  2. Mild- persists for a few minutes to few hours
  3. Moderate - persists for hours and is relieved by rest or sleep
  4. Severe - requires the use of medications for relief

23. Do you use your device at night before sleeping with the lights switched off?

  1. Yes
  2. No

24. Do you use your multiple devices at the same time?

  1. Yes
  2. No

25. Do you have a refractive error which requires you to wear spectacles or contact lenses?

  1. Yes
  2. No

26. If yes, what refractive error do you have?

  1. Simple myopia
  2. Simple Hypermetropia
  3. Astigmatism
  4. I don't know

27. Have you heard about digital eye strain?

  1. Yes
  2. No

28. Are you aware of the symptoms of digital eye strain?

  1. Yes
  2. No

29. Do you know about the effects of blue light emitted from digital devices?

  1. Yes
  2. No

30. Have you heard about the 20-20-20 rule?

  1. Yes
  2. No

31. Do you know the ideal working distances for each digital device?

  1. Yes
  2. No

32. Do you use applications to control the brightness of your display screen?

  1. Yes
  2. No

33. By how much has your digital device use increased during this COVID Lockdown period?

  1. Increased by < 2 h
  2. Increased by 2–4 h
  3. Increased by 4–6 h
  4. Increased by more than 6 h
  5. Not increased.

  References Top

Sandars J, Patel R. The challenge of online learning for medical education during the COVID-19 pandemic. Int J Med Educ 2020;11:169-70.  Back to cited text no. 1
Blehm C, Vishnu S, Khattak A, Mitra S, Yee RW. Computer vision syndrome: A review. Surv Ophthalmol 2005;50:253-62.  Back to cited text no. 2
Coles-Brennan C, Sulley A, Young G. Management of digital eye strain. Clin Exp Optom 2019;102:18-29.  Back to cited text no. 3
Sanodiya I, Kujur A, Sirohi S, Khatri AK. A cross sectional overview of digital eye strain: a growing health concern in this digital age in central India (Madhya Pradesh). Int J Community Med Public Health 2019;6:4828.  Back to cited text no. 4
Sheppard AL, Wolffsohn JS. Digital eye strain: Prevalence, measurement and amelioration. BMJ Open Ophthalmol 2018;3:e000146.  Back to cited text no. 5
Gowrisankaran S, Sheedy JE. Computer vision syndrome: A review. Work 2015;52:303-14.  Back to cited text no. 6
Abudawood GA, Ashi HM, Almarzouki NK. Computer vision syndrome among undergraduate medical students in King Abdulaziz University, Jeddah, Saudi Arabia. J Ophthalmol 2020;2020:1-7.  Back to cited text no. 7
Al Tawil L, Aldokhayel S, Zeitouni L, Qadoumi T, Hussein S, Ahamed SS. Prevalence of self-reported computer vision syndrome symptoms and its associated factors among university students. Eur J Ophthalmol 2020;30:189-95.  Back to cited text no. 8
Iqbal M, El-Massry A, Elagouz M, Elzembely H. Computer vision syndrome survey among the medical students in Sohag University Hospital, Egypt. Ophthalmol Res 2018;8:1-8.  Back to cited text no. 9
Mowatt L, Gordon C, Santosh ABR, Jones T. Computer vision syndrome and ergonomic practices among undergraduate university students. Int J Clin Pract. 2018 Jan;72(1):10.   Back to cited text no. 10
Logaraj M, Madhupriya V, Hegde S. Computer vision syndrome and associated factors among medical and engineering students in chennai. Ann Med Health Sci Res 2014;4:179-85.  Back to cited text no. 11
[PUBMED]  [Full text]  
Shantakumari N, Eldeeb R, Sreedharan J, Gopal K. Computer use and vision-related problems among university students in ajman, United arab emirate. Ann Med Health Sci Res 2014;4:258-63.  Back to cited text no. 12
[PUBMED]  [Full text]  
Reddy SC, Low CK, Lim YP, Low LL, Mardina F, Nursaleha MP. Computer vision syndrome: A study of knowledge and practices in university students. Nepal J Ophthalmol 2013;5:161-8.  Back to cited text no. 13
Jaiswal S, Asper L, Long J, Lee A, Harrison K, Golebiowski B. Ocular and visual discomfort associated with smartphones, tablets and computers: What we do and do not know. Clin Exp Optom 2019;102:463-77.  Back to cited text no. 14
Bhanderi DJ, Choudhary S, Doshi VG. A community-based study of asthenopia in computer operators. Indian J Ophthalmol 2008;56:51-5.  Back to cited text no. 15
[PUBMED]  [Full text]  
Nakaishi H, Yamada Y. Abnormal tear dynamics and symptoms of eyestrain in operators of visual display terminals. Occup Environ Med 1999;56:6-9.  Back to cited text no. 16
Schellini S, Ferraz F, Opromolla P, Oliveira L, Padovani C. Main visual symptoms associated to refractive errors and spectacle need in a Brazilian population. Int J Ophthalmol 2016;9:1657-62.  Back to cited text no. 17
Hashemi H, Saatchi M, Yekta A, Ali B, Ostadimoghaddam H, Nabovati P, et al. High Prevalence of Asthenopia among a Population of University Students. J Ophthalmic Vis Res 2019;14:474-82.  Back to cited text no. 18
Patel S, Henderson R, Bradley L, Galloway B, Hunter L. Effect of visual display unit use on blink rate and tear stability. Optom Vis Sci 1991;68:888-92.  Back to cited text no. 19
Tsubota K, Nakamori K. Dry eyes and video display terminals. N Engl J Med 1993;328:584.  Back to cited text no. 20
Sheedy JE, Truong SD, Hayes JR. What are the visual benefits of eyelid squinting? Optom Vis Sci 2003;80:740-4.  Back to cited text no. 21
Gowrisankaran S, Nahar NK, Hayes JR, Sheedy JE. Asthenopia and blink rate under visual and cognitive loads. Optom Vis Sci 2012;89:97-104.  Back to cited text no. 22
Hirota M, Uozato H, Kawamorita T, Shibata Y, Yamamoto S. Effect of incomplete blinking on tear film stability. Optom Vis Sci 2013;90:650-7.  Back to cited text no. 23
Hupert N, Amick BC, Fossel AH, Coley CM, Robertson MM, Katz JN. Upper extremity musculoskeletal symptoms and functional impairment associated with computer use among college students. Work 2004;23:85-93.  Back to cited text no. 24
Toh SH, Coenen P, Howie EK, Smith AJ, Mukherjee S, Mackey DA, et al. A prospective longitudinal study of mobile touch screen device use and musculoskeletal symptoms and visual health in adolescents. Appl Ergon 2020;85:103028.  Back to cited text no. 25
Lee JW, Cho HG, Moon BY, Kim SY, Yu DS. Effects of prolonged continuous computer gaming on physical and ocular symptoms and binocular vision functions in young healthy individuals. PeerJ 2019;7:e7050.  Back to cited text no. 26
Agarwal S, Goel D, Sharma A. Evaluation of the Factors which Contribute to the Ocular Complaints in Computer Users. J Clin Diagn Res 2013;7:331-5.  Back to cited text no. 27
Rahman ZA, Sanip S. P2-493 Computer vision syndrome: the association with ergonomic factors. J Epidemiol Community Health 2011;65:A357.  Back to cited text no. 28
Moon J, Choi SH, Yoon CH, Kim MK. Gut dysbiosis is prevailing in Sjögren's syndrome and is related to dry eye severity. PLoS One 2020;15:e0229029.  Back to cited text no. 29
Masthi NR, Manasa AR. An exploratory study on violence among the college students in Urban Bengaluru, Karnataka, India. Indian J Public Health 2019;63:380-2.  Back to cited text no. 30
[PUBMED]  [Full text]  
Kerala University of Health Sciences. Syllabus for Courses Affiliated to the Kerala University of Health Sciences-Bachelor of Medicine and Bachelor of Surgery; 2015. Available from: http://www2.kuhs.ac.in/kuhs_new/images/uploads/pdf/academic/courses-syllabus/medicine/New_MBBS_16-05-2018.pdf. [Last accessed on 2020 Nov 15].  Back to cited text no. 31


  [Figure 1]

  [Table 1], [Table 2], [Table 3], [Table 4]


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