The first case of COVID-19 in Turkey was announced in March 11 by the Turkish Ministry of Health, on the very same day the pandemic was declared by the WHO [13, 14]. The subjects of our study consisted of the cases that presented to our outpatient department between August and December 2020, taking into account that the schools were closed and home-education started in March 2020.
The negative effect of close work and the positive effect of daylight in keeping myopia progression under control have been demonstrated by other studies [15]. Children staying at home during the pandemic and attending online education has increased the concerns about myopia progression. The results of our study have revealed that progression in the last year, within the age range of 8–17 years, is significantly higher than in the previous years. Additionally, spending 2 hours daily in an outdoor activity and living in a detached house were both found to decrease myopic progression. However, the effect of the duration of digital device use and the type of device used (smartphone, tablet, television) on myopia progression, was not found to be statistically significant.
Wang et al. have recently reported a 1.4 to 3 times increase in the myopia prevalence in 2020 in children aged 6–8 years, compared to the previous five years, with the ‘photoscreening’ test in over one hundred thousand children [16]. We evaluated the follow-up examinations of children with a diagnosis of myopia instead of children newly diagnosed with myopia. Wang et al. did not use cycloplegia for the refraction evaluation in children [16]. The myopia results of photoscreening-based devices are known to be exaggerated and to be affected by the experience of the person performing the measuring [17, 18]. Although these devices are useful in preverbal and nonverbal children, the general ophthalmological approach in school-age children is to determine cycloplegic refraction values [19]. We only included the cases that had undergone cycloplegic evaluation in our study, in order to ensure healthy results.
The relationship of long-term exposure to digital device screens with myopia is still controversial and some studies support this relationship, while others claim the opposite [20, 21]. Interestingly, the duration of reading, watching television or playing games on the computer has been suggested to influence myopia’s progression, rather than its occurrence, in the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error Study [22]. However, this may not be due to the effect of digital screens on the progression alone and could also be influenced by the “substitution effect”, as in the indirect decrease of the outdoor activity related to the increased time spent in front of the screen [23]. The effect on myopia of the activities performed in front of the digital screen, may not be equivalent to the effect of reading and writing in traditional education [24, 25]. Dopamine release in the retina is stimulated by daylight and suppresses the axial expansion of the eye [26, 27]. In addition, studies have revealed that the dopaminergic system in the frontal lobe is activated by the use of a digital device [28]. The effect of display devices on the retinal dopamine levels is not known, however Spiperone, a dopamine antagonist, has been shown to inhibit the protective effect of light against the increase of the ocular axial length in experimental models [29]. It has not been possible to demonstrate the relationship between myopia progression and the duration of use of a digital display device such as a tablet, smartphone, or computer with our study.
Outdoor activities have previously been shown to decrease the occurrence and progression of myopia [30, 31]. He et al. have reported that every additional 40 minutes of outside activities decreases myopia incidence by 23% [30]. Wu et al. have suggested that myopia progression in children who spent more than 11 hours a week outdoors decreases by 53% [31]. In general, 2 hours of outdoor activities per day is assumed to decrease myopia progression in school age children [7]. We similarly observed that myopia progression was 33% less in children with 2 hours of outdoor activity daily, even though the duration spent in front of the screen was similar. Although outdoor activities had a protective effect on myopia progression in our study, we did not observe a similar protective effect on the myopia progression rate. This result indicates that myopia progression occurs as a result of multiple factors, including environmental ones.
The type of house the child lives in is one of these environmental factors and we found it to be an independent risk factor for myopia progression. Similarly, a relationship between the type of the house the subject lives in and myopia, was revealed in a study conducted in Australia [20]. Myopia was reported to be more common in children living in apartment buildings compared to those living in detached houses in the same study [20]. He et al. found a significant relationship between school location and myopia [32]. Wu et al. reported an increase in the myopia prevalence with increasing number of floors in the building [33]. We think that accepting myopia as a public health problem could be effective in the intensification of screening in pre-school and school-aged children, as well as in designing cities in the fight against myopia.
The limitations of this study include the lack of data on pre-school children, the potential bias resulting from the information about the time spent in front of the screen and outside activities being self-reported, by way of the telephone, the accuracy of which could not be verified. The lack of biometry or keratometry information and the inability to determine the cause-effect relationship, as a result of the study’s cross-sectional design, are also limitations. A German study comparing refractive error information obtained from the patient statements with the information obtained from the opticians, has shown the two to be very similar [34]. Our study is, however and to the best of our knowledge, the first to evaluate the effect of home education during the COVID-19 pandemic in myopic children, using cycloplegic refraction results. It is also the first study to investigate the effect of the technological devices used for home education on myopia progression.
In conclusion, home education during the COVID-19 pandemic has increased the myopia progression rate in children, compared to the previous years. This increase has been found to be related to the duration of outdoor activities, as reported previously. A detached type of housing allows for a child to perform outside activities easily, while at home. During home confinement, education programs of school children should be designed while taking into account preventive measures for MP, in particular for allowing children to spend at least two hours of outdoor time per day.