Table 3.

Review of literature of digital eye strain during the COVID-19 pandemic

S. no.	Authors and country	Demographics	Risk factors	Clinical features	Investigations	Outcome	Conclusion
1	Wangsan et al. Int J Environ Res Public Health. 2022 Apr; 19(7): 3996 [53] Thailand	527 students, 70.40% females, mean age 20.04 ± 2.17 years	Female gender, atopic eye disease, dry eyes, itching, red eye, eye pain, astigmatism, previous refractive surgery, tear substitute use, contact lens use, mobile and tablet use	Eye pain-96.5%, burning sensation-92.5%, headache 90.08%, defective vision-15.95	CVS-Questionnaire (CVS-Q), CVS was diagnosed with a score of CVS-Q ≥ 6	Prevalence of CVS was 81%, distance less than 20 cm (52.7 vs. 40%), less brightness less 14.8 vs. 7.0%) and glare or reflection on display (47.8 vs. 29.0%) were associated with CVS	Social distancing is mandatory, online classes are unavoidable, increased screen was associated with increases prevalence of CVS. Laptop/desktop should be preferred over mobile phone
2	Cai et al. Front Med (Lausanne), 2022 Mar 21;9:853293 [54] China	115 children with myopia	Strict home confinement, hereditary, closed indoor work time, excess exposure to electronic gadgets Protective factors- age, rest time, sleep time, and distance from the device while usage	Asthenopic symptoms	Axial length assessment (IOL Master 700) and refractive errors (without cycloplegia), visual function, convergence insufficiency symptom survey (CISS) and eye care habits questionnaire	Axial length elongation was 35% higher than normal, positively correlated with severe asthenopia (r = 0.711), negative with age (r =  − 0.442), distance from eyes (− 0.238)	Decreased outdoor activities and increased screen time accelerated myopia progression by 1/3
3	Demirayak et al. Indian J Ophthalmol 2022 Mar;70(3):988–992 [45] Turkey	692 children under the age of 18 years, mean age 9.72 ± 3.02 years, 360 (52%) were girls, 62.57% were students in primary school	Computer use (61.7%), smartphones (57.8%), mean duration of display device use 71.1 ± 36.02 min	Headache (52.2%), eye fatigue (49.3%), and eye redness (49.3%) and double vision-8.8%	Online electronic survey using Google Forms	48.2% experienced 3 or more symptom, male gender and age were independent risk factors for 3 or more symptoms	Digital device use during the pandemic exacerbated the DES among children
4	Basnet et al. JNMA J Nepal Med Assoc, 2022 Jan 15;60(245):22–25 [55] Nepal	318 subjects	Digital device use, tablet use, computer, and smartphone	Eye strain-199 (62.6%), tiredness of eyes-162 (50.9%)		Prevalence of DES was found to be 94.3%	Prevalence of DES has increased during COVID-19 pandemic
5	Regmi A et al. Clin Exp Optom. 2022 Feb 14:1–7 [56] India	1302 participants	Females spending more than 6 h on digital devices, taking breaks from digital devices after 2 h, inability to maintain a fair sleep schedule, and inability to make ergonomic modifications at home		Electronic communication sources using Google Forms	94.5% had one or more visual and ocular symptoms associated with digital devices usage. 43.1% reported that these symptoms began post-lockdown	A high prevalence of visual/ocular symptoms (43.1%) and work-related musculoskeletal disorder (45%) were reported during COVID-19 lockdown
6	Mohan A et al. Indian J Ophthalmol. 2022 Jan;70(1):241–245 [17] India	133 children (266 eyes)	History of rapid progression in pre-COVID-19 era (p = 0.002) and sun exposure < 1 h/day (p < 0.00001)			Annual myopia progression was found to be statistically significant during COVID-19 as compared with pre-COVID-19 (0.90 vs. 0.25 D, p < 0.00001). A total of 45.9% of children showed an annual progression of ≥ 1 D during the pandemic as compared with 10.5% before the COVID-19 (p < 0.00001)	Rapid myopia progression in children during current pandemic and children should be provided with socially distant outdoor activities to increase their sun exposure and diminish the rate of myopia progression
7	Kaur K, J Pediatr Ophthalmol Strabismus. 2021 Dec 20:1–12 [46] India	305 responses	Digital device use	Headache was the most common complaint in 100 children (51% of total symptomatic), followed by ocular pain in 19 children (9.64% of total symptomatic)	Online questionnaire using Google Forms	Prevalence of DES was found to be 64.6%	There is a strong need to bridge this knowledge gap and prevent the increased prevalence of myopia and digital eye strain in the future
8	Gupta R et al. J Curr Ophthalmol. 2021 Jul 5;33(2):158–164 [57] India	654 students, mean age: 12.02 ± 3.9 years, 332 (58%) females	Spectacle users, age, and duration of digital device	Redness (69.1%), heaviness of eyelids (79.7%), blinking (57.8%), blurred vision (56.9%), light sensitivity (56%)	Rasch-based Computer-Vision Symptom Scale was deployed to measure the DES	Mean CVS score of. class 1–5 was 26.1 ± 7.8, class 6–9 was 24.8 ± 6.6, class 10–12 was 29.1 ± 7.1. Mean CVS score was lowest in < 4 h group followed by 4–6 h and then > 6 h	The majority experienced at least one symptom of DES. There is a need to educate the masses about measures to prevent DES
9	Mohan A, et al. J Pediatr Ophthalmol Strabismus. 2021 Jul-Aug;58(4):224–231 [48] India	46 children; mean age of 14.47 ± 1.95 years	Digital devices for 4 h/day or more		Convergence Insufficiency Symptom Survey (CISS) questionnaire	Mean CISS scores were 21.73 ± 12.81 for digital device use < 4 h/day and 30.34 ± 13.0 for ≥ 4 h/day (p = 0.019). Mean near exophoria (p = 0.03), negative fusional vergence (p = 0.02), negative relative accommodation (p = 0.057), and accommodation amplitude (p = 0.002) were different between the two groups	Online classes for more than 4 h resulted in abnormal binocular vergence and accommodation
10	Mohan A et al. Strabismus. 2021 Sep;29(3):163–167 [47] India	8 children, mean age 12.5 ± 4.2 years, all 8 males	Emmetropia (5), myopia (1), pseudomyopia (1), hyperopia (1)		Diplopia, Hess chart, visual acuity by Snellen chart, alternate prism cover test, cycloplegic retinoscopy, neurological examination	Mean duration of smartphone use 4.6 ± 0.7 h, children attending classes for > 4 h/day. The angle of deviation for near and distance were 48.1 ± 16.4 PD and 49.3 ± 15.9 PD, respectively, with normal ocular motility	Prolonged near work especially using smart phone for e-learning might lead to AACE in children
11	Salinas-Toro D et al. Int J Occup Saf Ergon. 2021 Jul 7:1–6 [58] United States	1797 respondents; mean age of respondents 40.5 ± 11.1 years, and 69.9% were female	Female gender, refractive surgery, rosacea, depression, previous dry eye disease, keratoconus, blepharitis, occupation, contact lens use	Soreness, pain, foreign body sensation, redness, visual fatigue, redness and blurred vision	Ocular symptom index, DED (dry eye questionnaire 5 [DEQ-5] questionnaire	The mean number of teleworking weeks was 10.2 ± 3.0. All DES symptoms presented a significant increase (p < 0.001). The mean DEQ-5 score was 8.3 (SD 4.9). Women had a higher score (p < 0.001)	Visual display terminal hours are related to increase in DES symptoms and high prevalence of DED
12	Zheng et al. J Med Internet Res, 2021 Apr 30; 23 (4): e 24316 [59] China, Singapore, Ireland, and Australia	1009 children, 2 groups – interventional group (485)—exercises and ocular relaxation, and access to a digital behavior change intervention, or control group (469)—health education information only Mean age 13.5 ± 0.5 years, 499 males	Smartphone use, gender, use of glasses, parental education, smoking and family history	Eye strain, anxiety, sleep disturbance,	Health education information promoting exercise and ocular relaxation, and access to a digital behavior change intervention, with live streaming and peer sharing of promoted activities	Mean anxiety score in the intervention group was greater (− 0.23) as compared to the control group (0.12). A significant reduction in eye strain was observed in the intervention group (− 0.08) as compared to controls (0.07)	Digital behavior change reduced anxiety and eye strain among children
13	Gammoh Y. Cureus. 2021 Feb 26;13(2):e13575 [60] Jordan	382 students, mean age of participants was 21.5 years (± 1.834), male:female ratio was 1:1.56	Digital device use for > 6 h per day	Tearing (59%), headache (53%), and increase sensitivity to light (51%)	Computer Vision Syndrome Questionnaire (CVS-Q)	The prevalence of CVS was found to be 94.5%. Tearing was most common-(59%), double vision was least common among students-18.3%. DD use for > 6 h/ day was present in 55.5% patients, and 30.7% of reported pain in joints of fingers and wrists after using a mobile phone	CVS is highly prevalent among Jordan university students. Safe habits in digital device use are recommended to prevent DES
14	Alabdulkader B. Clin Exp Optom. 2021 Aug;104(6):698–704 [49] Saudi Arabia	1939 participants, mean age was 33 ± 12.2 years and 72% were women	Digital device use duration, use of multiple devices, age, optical correction, and status of employment		Self-reported questionnaire	Incidence of digital eye strain was 78%	Importance of regular eye examination, limiting screen time, the 20–20-20 rule, and the use of lubricating drops to help reduce the symptoms of DES should be emphasized
15	Ganne P et al. Ophthalmic Epidemiol. 2021 Aug;28(4):285–292 [61] India	941 responses from online classes students (688), online classes teachers (45), and the general population (208)	Students attending online classes, those with eye diseases, greater screen time, screen distance < 20 cm, using gadgets in dark and infrequent/no breaks		Pre-validated questionnaire	DES prevalence was higher among students taking online classes (50.6%) compared to the general public (33.2%). An increase in screen time has been observed during the pandemic compared to pre-pandemic time	There is a need to educate about ergonomics of screen usage. There is need to reduce the online classes duration and working hours for professionals to control the epidemic of DES
16	Mohan A et al. Indian J Ophthalmol. 2021 Jan;69(1):140–144 [44] India	217 parents, mean age 13 ± 2.45 years	Age > 14 years, male gender, smartphone use, > 5 h of digital device use and > 1 h/day of mobile games		Online electronic survey—Computer Vision Syndrome Questionnaire	Mean digital device use duration during COVID era (3.9 ± 1.9 h) is more than pre COVID era (1.9 ± 1.1 h). 36.9% used digital devices > 5 h in COVID era as compared to 1.8% pre COVID era. Smartphones were most common digital device used (61.7%). 49.8% attended online classes for > 2 h per day	DES prevalence increased among children in COVID era. Duration, type, and digital device distance ergonomics can avoid DES in children
17	Bahkir FA et al. Indian J Ophthalmol. 2020 Nov;68(11):2378–2383 [62] India	407 responses, mean age was 27.4 years, 55.5% were males and 44.5% were female	Female gender, student population	Headache, eye pain, heaviness of eyelids, redness, watering, burning sensation, dryness, increased light sensitivity, itching, excessive blinking, difficulty in focusing printed text, blurred vision, foreign body sensation, double vision	Open online survey through social media platforms	93.6% respondents reported increased screen time after lockdown. An average increase of 4.8 ± 2.8 h per day was reported. Total daily usage was found to be 8.65 ± 3.74 h. 62.4% reported sleep disturbances. 95.8% experienced at least one symptom related to DES, and 56.5% agreed to increased frequency and intensity of symptoms post lockdown	Awareness should be created about prevention of DES, and additional measures should be explored to control the adverse effects related to digital devices