Table 2.

Summary of research work published on digital eye strain prior to the COVID-19 pandemic

S. no.	Authors and Country	Demographics	Risk factors	Clinical features	Investigations	Outcome	Conclusion
1	Sancho et al. Int J Environ Res Public Health, 2022 Apr 8;19(8):4506 [38] Spain	241 subjects, 64.3% women, Mean age, 45.49 ± 10.96 years (18–65 years age group)	Amblyopia, dry eyes, retinal pathologies, occupational use of digital devices (DD), number of hours and years of DD use, scheduled break	Burning, itching, foreign body sensation, eye blinking, redness, pain, tearing, heaviness, dryness, blurred vision, double vision, etc.	TBUT, Schirmer’s test, Rasch–Andrich Rating Scale Model Analysis, Italian Version of the Computer Vision Syndrome Questionnaire (CVS-Q IT©)	Prevalence of CVS was 67.2%, blurred vison-63.5%, worsening of sight, 62.3%, headache 56%. Least prevalent eye strain-11.2%, colored halos-16.2% and double vision-17.4%	CVS-Q IT© is a simple, reliable, and valuable tool for assessing CVS in adults
2	Auffret et al. J Fr Ophtalmol 2022 Apr;45(4):438–445 [39] France	52 participants	Chronic exposure to digital devices	Ocular discomfort, blurred vision, photophobia	Short-term screen exposure, chronic screen exposure, ocular discomfort questionnaire refraction, phoria, near point of accommodation and convergence, fusional vergence and binocular amplitude facility	No significant difference between control group and exposed group in any objective parameters Exposed group have high discomfort score for near (p-0.04), intermediate (p-0.02) blurred vision and light sensitivity (p-0.04)	Binocular balance is affected by chronic and intensive screen use
3	Moore et al. Ophthalmic Physiol Opt, 2021 Nov;41(6):1165–1175 [40] United Kingdom	406 respondents	Digital device use		Anonymous online questionnaire, covering attitude and understanding of DES	Estimations of the proportion of patients affected by DES were lower than reports in the literature (median 25%, IQR 10-50%). Most respondents always (60.6%) or frequently (21.9%) inquired about device usage in routine case history taking, and also asked follow-up questions, although 29.3% only asked about the presence of symptoms half the time or less	DES causes frequent and persistent symptoms, and practitioners reported high levels of confidence in discussing DES, patients can expect to receive advice on symptoms and management from their optometrist
4	Zayed HAM et al. Environ Sci Pollut Res Int. 2021 May;28(20):25187–25195 [41] Egypt	108 IT professionals	Female gender, age ≥ 35 years, computer use > 6 h/day, refractive error, not adjusting workstation ergonomics, no breaks during computer work, dry environment	Headache (81.5%), burning of eyes (75.9%), and blurred vision (70.4%)	Computer vision syndrome questionnaire (CVS-Q)	Prevalence of DES was found to be 82.41%	DES can be prevented by increasing knowledge and awareness about eye health, proper ergonomic computer training, and suitable comfortable workplace environment
5	Meyer D et al. Cont Lens Anterior Eye. 2021 Feb;44(1):42–50 [42] United States	Six hundred and two soft contact lens (SCL) wearers and 127 non-contact lens (non-CL) wearers using digital devices at least 4 h per day		Primary sensations eye strain/pain, soreness, tired eyes, and headaches Secondary or surface sensations burning, eye irritation, tearing and dryness Visual sensations blurred/double vision and words move/float	Questionnaire assessing frequency and severity of 10 common symptoms associated with eye fatigue related to DES	89% of SCL wearers reported eye fatigue more than once per month, and > 60% reported more than once per week Dryness and irritation were more common among SCL wearers	Eye fatigue is highly common among both soft contact lens and non-contact lens wearers. The frequency or severity is same among SCL users and other group
6	Al Dandan O etal, Acad Radiol. 2021 Aug;28(8):1142–1148 [43] Saudi Arabia	198 radiologists (111 males and 87 females), including 40.9% residents, 27.3% senior registrars, and 27.3% consultants	Female sex and taking breaks once or twice a day only		Online survey	26.8% underwent an eye examination within past one year and 50.5% experienced DES	DES is common among radiologists. It is more common among radiology residents, females, and those not taking frequent breaks
7	Ichhpujani P et al. BMC Ophthalmol. 2019 Mar 12;19(1):76 [35] India	576 adolescents attending urban schools	Preference to lie down		Surveyed regarding their electronic device usage	18% (103) experienced eyestrain at the end of the day 18% experienced symptoms related to DES. 20% students aged 11 years use digital devices on daily basis, in comparison with 50% aged 17. In addition to homework aids, one-third of the participants reported using digital devices for reading instead of conventional textbooks. 77% students prefer sitting on a chair while reading, 21% prefer to lie on bed and 2% students alternating between chair and bed	The increased use of digital devices by adolescents brings a new challenge of digital eyestrain at an early age