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.

In this letter, a compact octagonal shaped fractal ultrawideband multiple-input-multiple-output (MIMO) antenna is presented and its characteristics are investigated. In order to achieve the desired miniaturization and wideband phenomena, self-similar and space filling properties of Koch fractal geometry are used in the antenna design. These fractal monopoles are placed orthogonal to each other for good isolation. Moreover, grounded stubs are used in the geometry to provide further improvement in the isolation. The band rejection phenomenon in wireless local area network (WLAN) band is achieved by etching a C-shaped slot from the monopole of the antenna. The proposed antenna has compact dimensions of 45 mm × 45 mm and exhibits quasi-omnidirectional radiation pattern. In addition, it shows an impedance bandwidth (S 11 <-10dB) from 2-10.6 GHz with isolation better than 17dB over the entire UWB range. Diversity performance is also evaluated in terms of ECC and capacity loss. The measured results show good agreement with the simulated ones.

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Purpose: This study was performed to compare the rate of progression of myopia before and during the COVID-19 pandemic and to assess the risk factors of hastened progression. Methods: All children with myopia of spherical equivalence ≤ −0.5 D with at least two prior documented refractions 6 months and 1 year before were included. The annual progression rate before COVID-19 and during COVID-19 was calculated. Annual myopia progression was categorized as no progression (0), slow progression (<1 D), and fast progression (≥1 D). Results: A total of 133 children (266 eyes) aged 6–18 years were included in the study. Mean 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). In multivariate analysis, history of rapid progression in pre-COVID-19 era ( P = 0.002) and sun exposure <1 h/day ( P < 0.00001) were found to be independent risk factors for rapid myopia progression. Conclusion: Parents should consider risk of 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.