In the Shandong Province, a substantial proportion of adolescents aged 12 ~ 15 confronts the challenge of myopia, mirroring wider public health concerns. During this critical period of adolescent development, a significant number are grappling with vision-related issues, potentially affecting their long-term ocular health. This prevalence of myopia among young adolescents not only highlights the need for increased awareness and preventive measures but also underscores the importance of early detection and management to safeguard their future vision health.
The present study uncovered gender disparities in the prevalence of myopia, observing a marginally higher incidence in female adolescents compared to their male counterparts, a finding that aligns with previous research [23]. This discrepancy may be attributed to differences in physiological changes experienced during adolescence between genders. Notably, significant choroidal thinning, which is linked to the rapid progression of myopia, has been reported to be more pronounced in females [24]. Furthermore, the correlation between serum sex hormone levels and the onset and progression of myopia in adolescents has been established. Studies have shown that levels of follicle-stimulating hormone and luteinizing hormone are higher in females than in males, potentially contributing to the observed variations in myopia rates between the sexes [25]. In addition, a specific form of severe myopia, which is exclusive to females and characterized by central macula dysfunction, has been identified as a monogenic genetic disorder caused by mutations in the ARR3 gene [26]. This emerging evidence underscores the importance of considering gender-specific factors in the study and management of myopia.
This study identified age as a critical determinant in the prevalence of myopia among adolescents. Consistent with prior findings [27], our data indicated that the rate of myopia tended to increase with age in adolescents. The adolescent period is characterized by rapid growth and significant developmental changes in the human body [28], which include physiological transformations impacting vision. This phase is particularly vital for the development of the visual system, marking adolescence as a period of increased susceptibility [29]. During this time, the ocular structure undergoes continued development, becoming more receptive to external environmental influences. As adolescents age, their increased engagement in activities and environments conducive to myopia can exacerbate the risk. This heightened exposure, combined with the eye's enhanced sensitivity during this phase, is associated with the elongation of the eyeball [30], potentially accelerating the onset and progression of myopia.
In the current study, a significant variation in myopia risk was identified based on family location, with urban areas exhibiting a higher prevalence compared to rural regions. This observation aligned with similar findings demonstrating elevated rates of myopia among urban adolescents relative to their rural counterparts [31]. The disparity in myopia incidence between urban and rural settings is complex and may be attributed to differences in population densities. Nevertheless, it is essential to recognize that the etiology of myopia extends beyond mere geographical factors. It encompasses a combination of environmental and behavioral influences [32, 33]. Children in urban areas often have the advantage of better economic conditions compared to rural areas. This economic disparity allows urban children access to environments that might inadvertently increase their risk of developing myopia [16]. Such environments often promote extended periods of ocular exertion, which may significantly contribute to the observed variance in myopia prevalence between urban and rural children.
This study highlighted the significant role of parental myopia in the development of myopia among adolescents. Corresponding with similar research, it was noted that children with one or both parents affected by myopia were at a greater risk of developing the condition themselves [34]. The influence of genetics on adolescent myopia is indisputably substantial [35]. Further investigations have identified specific genetic markers that correlated with an increased risk of myopia [36]. A history of myopia in parents or other family members is indicative of an elevated likelihood of adolescents inheriting these genetic predispositions. Although these genetic factors do not inevitably lead to the development of myopia, they significantly increase the susceptibility to this condition in adolescents.
The current study identified the use of eyes in positions such as lying down or leaning forward as a contributing factor to myopia in adolescents. This aligned with recent research indicating that frequently adopting such postures was a risk factor for adolescent myopia [37]. These postures necessitate extra effort to control eye movements for focusing, resulting in continuous strain on ocular muscles. This sustained tension can lead to visual fatigue and potentially precipitate the onset of nearsightedness.
This research highlighted that engaging in visual tasks while walking or riding in the car, a behavior frequently observed among adolescents, played a significant role in the onset and progression of myopia. Parallel findings have identified this practice as a risk factor for adolescent myopia [38]. This practice is characterized by the challenge of maintaining a stable visual focus. The eyes are required to continuously adapt to varying distances and shifting focal points, leading to an increased demand for ocular adjustments.
This study underscored the potential of outdoor exercise in mitigating myopia risk. Similar research supported the protective role of outdoor physical activities against the development of myopia in adolescents [39]. This preventive effect is likely attributed to the enhancement of blood circulation within the eye due to physical activities, which in turn inhibits the excessive elongation of the eyeball, a key factor in the development of myopia in children and adolescents [23]. Furthermore, increased exposure to sunlight aids in the synthesis of Vitamin D in the human body, offering a protective effect in maintaining normal vision [40]. Additionally, it is proposed that outdoor exposure contributes to myopia prevention through the photostimulation of retinal dopamine release. The increase in dopamine levels is believed to impede the axial elongation of the eye, which constitutes the fundamental structural change in myopia [41]. Moreover, outdoor activities provide opportunities for distant viewing, which is beneficial for the regulation and relaxation of the eyes [42]. The intensity of outdoor illumination significantly surpasses that of indoor environments. Under the influence of high ambient light, the pupil constricts and depth of field increases, which collectively serves to decelerate the onset and progression of myopia [43].
This study identified maintaining proper reading and writing postures as a key factor in preventing myopia. Supporting research has indicated that not maintaining good postures during these activities constituted a risk factor for the development of myopia in adolescents [44]. The posture adopted during reading and writing influences not only the pleasure and effectiveness of these activities but also impacts retinal image quality, convergence and accommodation demands, and binocular comfort, all of which can contribute to the incidence of myopia [45].
This study revealed that prolonged near-vision activities were a significant risk factor for myopia in adolescents. Similar studies have shown that extended use of computers [46] and smartphones [47], as well as prolonged reading periods [48], especially when the eyes were too close to screens or books, can accelerate the progression of myopia [49]. These activities impose greater demands on accommodation and vergence due to the axial elongating effects of excessive accommodative convergence and peripheral defocus. Additionally, the small screens and font size on smart devices encourage closer viewing distances than conventional print materials, exacerbating these effects [50].
This study found that adequate sleep duration was associated with myopia prevention in adolescents. Research supported that sufficient sleep served as a protective factor against myopia [51]. The beneficial effect of sleep on myopia might be attributed to the relief or rest it provides to the ciliary muscle, thereby helping to prevent or alleviate myopic progression [52].