The rapidly growing usage of Internet technologies, including among children, adolescents and youth, together with younger age of users and increased duration of the Internet use by young people, were noted in the UNICEF Annual Report 2017 [1].

Digital environment substantially changes childhood and adolescence due to its contribution to many social processes (acquiring information and education, communication and maintaining social ties, entertainment and leisure activities, engagement with society and lifestyle) [2-8].

However, it is important to note the declining health of the juvenile population, especially the visual organ health. This gives relevance to development of preventive measures that would reduce adverse effects of digital environment on the health of younger generation [9, 10].

The study was aimed to assess the impact of life activity upon exposure to digital environment on the organ of sight in schoolchildren and college students.

METHODS

The study was carried out at Dolgoprudny gymnasium (Moscow Region) and Pirogov Russian National Research Medical University in 2017-2020. A total of 805 schoolchildren and college students underwent ophthalmologic examination (150 primary school students, 130 secondary school students, 200 senior secondary school students, 325 college students). 

Visual acuity was assesed using the Golovin-Sivtsev table inserted in the Roth apparatus. The assessment results were presented in the following format: Vis^no/_correction (OD=…, OS=…). Malinovsky test was performed [11, 12].

Accommodative response was registered with the Speedy-K Ver. MF-1 autorefractor keratometer (Japan) (fig. 1). Monocular vision was tested. Visual stimuli were presented to patient at varying distances from the eye (from infinity to 20 cm), and refractive state was determined. Then the stimulus with this refraction value was presented (conditions for emmetropia were established). Later refraction of the stimulus was increased stepwise by 0.5 D: –0.5 D, –1.0 D, –1.5 D, –2.0 D, etc. (up to –5.0 D). Refractometer measured eye refraction amidst visual load applied many times during the study, and the data obtained went into computer to be processed and displayed in the form of diagrams. Indicators (coefficients) that characterized the ciliary muscle function were evaluated for quantification and comparative evaluation of dynamic changes in accommodography. Coefficients were calculated in the automatic mode using the specially designed software. Accommodative response coefficient reflects the degree of ciliary muscle tension. It depends on the ratio between the accommodative response and the accommodative stimulus at each “stage” of the study. Growth (decrease) in the accommodography was evaluated using the accommodography growth coefficient. Coefficient of microfluctuations is the coefficient of high frequency ciliary muscle microfluctuations [13].

The questionnaire, developed by specialists from the Research Institute of Hygiene and Health Protection of Children and Adolescents, used in multicenter studies aimed at providing medically safe digital technologies to children, was used as a basis and tailored to meet the requirements of the study reported. All authors had the following practitioner certificates: “Hygiene of Children and Adolescents”, “Ophtalmology”. The inclusion criteria were as follows: schoolchild, college student, informed consent submitted, ophthalmologic examination data available, questionnaire, correctly completed by the respondent or his/her legal representative. Exclusion criteria: different age group, no ophthalmologic examination data available, no correctly completed questionnaire. Correlation analysis was used to define the nature of the relationship between the students’ visual acuity and their daily total time of using the ED, as well as the duration of the ED continuous use (р≤0.05).

The study involved no risk to participants and met the requirements of biomedical ethics and the Declaration of Helsinki (1983). The study was approved by the Ethics Committee of Pirogov Russian National Research Medical University (protocol No. 159 dated November 21, 2016).

Statistical processing of the data was performed using the Statistica 13.0 software package.

RESULTS

No schoolchildren and college students not using electronic devices were found. Only 9.9% of primary school students, 2.7% of secondary school students, 1.9% of senior secondary school students, and 0.9% of college students did not use electronic devices every day. The students use stationary (personal computer, laptop) and mobile (smartphone, tablet) devices on a daily basis both during school day and during holidays.

Daily total time of using all electronic devices by children, adolescents and youth during school day and during holidays is presented in tab. 1.

High daily total time values of using the ED both during the school day and during holidays were obtained for all categories of respondents.

During the period of study, the daily total time of using the ED (both in educational and leisure activities) was about 2.0 hours in primary school students, 5.5 hours in secondary school students, 8.0 hours in senior secondary school students, and 11.0 hours in college students.

During holidays, the daily total time of using the ED by primary school and secondary school students increased by an average of 0.8-1.3 hours and accounted for 2.8–3.3 hours. In senior secondary school students and college students, the daily total time of using the ED increased by an average of 1.7-3.7 hours (р≤0.05).

When studying the students’ organ of sight by computed accomodography, it was found that ciliary muscle insufficiency (weakness) was the most common accommodative state, which was in line with the data reported in literature [14].

Accommodation weakness was detected in 88.76% of students with early stages of myopia (fig. 2). Accommodative response close to normal was less common (11.24%) (fig. 3).

The values of accommodative response obtained in schoolchildren with initial stages of myopia suggest poor blood circulation in long posterior ciliary arteries [15].

The relationship between the students’ visual organ condition and the daily total time of using stationary and mobile electronic devices during the school day and during holidays is presented in tab. 2.

Significant negative correlations were revealed between the students’ visual acuity and the daily total time of using the ED, as well as the duration of the stationary and mobile electronic devices continuous use (р≤0.05) [16].

It is shown, that with the first graders daily total time of using the ED increased by 2 hours and more, a significant decrease in a number of individuals with functional or chronic eye problems among them is observed. The prevalence of accommodative problems is increased (p≤0.05), and the trend of increasing the number of high myopia cases is noted (fig. 4).

DISCUSSION

Active development of the electronic industry over the past few decades has resulted in wide use of electronic devices, including by students in their life activities. Our findings illustrate the use of various ED types by the absolute majority of students, frequent and long-term use of ED by children, adolescents and youth during their studies, and increased visual load during holidays. The relationship between the increased duration of the stationary and mobile electronic devices continuous use, daily total time of using the ED and reduced visual acuity, increased prevalence of functional problems and chronic eye diseases in students had been established.

The long-term effects of using the electronic devices remain unknown. However, various short-term effects on the organ of sight, such as dry eye, burning eye, redness, blurry vision, floaters and diplopia, resulting from the use of ED, are often reported both in domestic and foreign literature sources [17, 18].

This group of symptoms is known as computer vision syndrome, which can affect the users of both stationary and mobile electronic devices. According to some reports, this syndrome affects 40% of office workers, “spending at least half of their time in the office” [19].

The relationship between the organ of sight disorders and the electronic device use duration was noted by some other authors. Thus, the relationship between using the smartphone by adolescents for over 2 hours per day more than doubled the number of complaints of pain and dry eyes [20].

The symptoms listed above do not last and vanish on cessation of using the ED [21].

A whole range of measures has been developed for prevention of such organ of sight disorders. However, children, adolescents and youth show low level of awareness of the issue, and, therefore, does not acquire skills of safe ED use, which adversely affects their health, i.e. the organ of sight health, compromises their quality of life and reduces their effectiveness [22].

Such organ of sight disorders may result from impaired function of accommodation system. The condition of the accommodation system affects dynamic refraction, which in turn affects central vision. Underestimation of the role of accommodation in the development of a number of disorders may leave the students unaided and limit their visual performance at any age. Enhanced accommodation associated with the long-term use of electronic devices in children can promote postnatal growth of eyeballs and increased eye refraction. Weak accommodation precedes myopia, is considered the first sign of myopia, and accompanies the clinical course of myopia [15].

We believe that the accommodative dysfunction revealed may be due to dysregulation of the ciliary muscle function resulting from altered vegetative processes, which leads to hemodynamic changes in the ocular circulation due not only to mechanical stretching of the sclera, but also to unbalanced vascular tone neurogenic regulation [23].

Moreover, changes in choroidal perfusion can also be the probable cause of myopia progression in schoolchildren. It can be assumed that in case of increased choroidal perfusion choroid can become the source of excessive retinoid  levels (retinoic acid, RA), which are unused in the biochemical reactions in the retina of individuals with myopia, and are accumulated in the known receptors of the sclera, being the closest structure [24-26].

RA accumulation in the sclera results in altered proliferation and differentiation of fibroblasts [27].

Further development of research in this field could contribute to eye protection in children, adolescents and youth in the context of exposure to digital environment [28-30].

CONCLUSION

Wide use of electronic devices by children, adolescents and youth against the background of increased incidence of the diseases of the eye and adnexa is of deep concern to ophthalmologists and hygienists. Studying the organ of sight disorders’ pathogenesis and the revealed negative correlation between the students’ visual acuity and the duration of continuous use and total daily use of the electronic devices indicate that there are some manageable risk factors, that contribute to development of this pathology. Under these circumstances, hygiene training for students aimed at acquiring knowledge and skills of safe electronic device use in the context of digital environment, as well as evolving commitment to healthy lifestyle during studies, during holidays and throughout the lifespan, should be one of the top priorities in preventive work at the current stage. Taking into account the early experience of using the ED, and the need for their use for education, preventive work should start at pre-school age, and hygiene training should reach not only students, but also their parents, educators and teachers. The students’ engagement with ED as a part of educational programme should comply strictly with the hygiene requirements.