A Review of the Role of the School Spatial Environment in Promoting the Visual Health of Minors

Rising childhood myopia rate has detrimental health consequences that pose a considerable challenge to health systems. The school spatial environment, which is where students are for the longest period of time, has a high health value for myopia systematic intervention. While research has demonstrated associations between physical daylight environments, medical gene and visual health, the literature currently lacks a synthesis of evidence that will act as a spatially-organized resource for school designers. This study is based on literature from the period 2000–2022 and has been taken from the Web of Science, scopus, Medline and CNKI core collection database. Collaboration, literature co-citation and quantitative and qualitative analysis, in addition to keyword co-occurrence are adopted to conduct a visual health research review. The results indicate that intensive near work activity (as a risk factor) and longer time spent outdoors (as a protective factor), are involved in visual health factors. Two main research themes are obtained and relate to: (1) The environment of visual work behavior (especially the near work learning environment) and adaptable multimedia learning environment; and (2) the environment of outdoor exposure behavior. Furthermore, with the variation of educational demands, models and concepts, there are different demands for near work behavior, and this study makes an important contribution by pointing to two future research directions, including the accurate and controllable environment of near work behavior, which operate in accordance with various educational mode requirements and the active design of the environment of outdoor exposure behavior. In referring to differences between regions and countries, as well as the development of the educational environment, it provides insight into how these demands can be controlled.


Introduction
Vision, the most dominant sense, plays a crucial role in obtaining information. Visual health, mental health and levels of well-being are closely interconnected [1], and the human body needs healthy vision in order to function optimally [2]. Rising childhood myopia problems with high incidence that occur in young ages pose a considerable challenge to health systems globally, and this is especially true in Asia [3]. Estimates of growth in the urbanization and human development index suggest that, by 2030, there may be 3.36 billion people with myopia across the globe. The number of people with high myopia, which is frequently accompanied by serious complications, is estimated to increase to 516.7 million in the same year [4]. The COVID-19 pandemic also greatly changed lifestyles, longtime online working and learning in ways that will aggravate the severity of the myopia problem. Take China as an example. As a result of increased large-scale online teaching, decreased physical activities and outdoor exposure during the 2020 pandemic,

Literature Search
We conducted a comprehensive literature search (through May 2022) that addressed myopia, the school spatial environment and school design, and minors. This study seeks to cover material that could impact the development of a conversion tool that will sustain both architecture designers and researchers who wish to establish an evidence-based visual health-promoting school design; it does not, to this extent, seek to determine or quantify a relationship between a pair of deliberately defined and measured variables.
We searched the following databases: Web of science, CNKI, Scopus and Medline (via pubmed). We used Medical Subject Headings (MeSH) search codes where possible, and used the following terms: (Schools[mesh] OR school*) AND ("facility design and construction" [mesh] OR "environment design" [mesh] OR architecture OR environment OR "school design" OR "building design" OR "built environment" OR "classroom design" OR "school room design") AND (visual health[mesh] OR myopia/prevention and control[mesh] OR "visual health promotion"[mesh] OR "short-sightedness" [mesh]). In engaging with databases that do not use MeSH, we used a similar key word structure. It should be pointed out that we also searched for these words in Chinese, and CNKI was our choice as the database because it has the most complete amount of Chinese journal data. In particular, some case studies on built cases will enlighten the translation of strategies.

Selection Criteria
In considering the myopia problem, we note that there are already several mapping reviews in both English and Chinese [6,8,9]. Accordingly, when addressing the specific topic of school spatial environment in promoting visual health, we opt for a scoping review methodology that includes different stages [10], which is adapted to translational purposes in practice.
Our review focuses on two themes: "factors related to minors' visual health; the relationship between school spatial environment and minors' visual health"; and "the contribution the spatial environment could make to visual health". Correlation with these two themes is the basis on which the literature is filtered.
First, thinking about the complexity of the visual system, which is composed of eye, optic nerves and pathways to and between different structures in the brain, means that discussions of minors' visual health mainly focus on "no refractive errors" (which means not contracting myopia). The literature is not limited to the study of myopia, as environmental factors that promote visual health behaviors are also covered. The reason for this is that the scope of "health" is much wider than "not sick", which refers to being in a perfect state [11]. Environmental effect is not a short-term sensitive pathogenic factor, but is instead long-term and wide-ranging. This study therefore firstly mapped the position of the environment factor with all other known factors and took this as the basic cognition.
Secondly, we identified 555 unique sources (491 in English and 64 in Chinese) that were potentially relevant to the topic of school spatial environment, and which could be used to promote visual health. This screening and removal of duplicates left 533 items. We selected studies for appraisal in a 2-stage process. First, we scanned titles and abstracts identified from the search strategy and limited articles published in the period January 2000-May 2022. Eligible studies (1) are randomized controlled trials with participants aged 6 to 18 years. This is taken as the baseline as this age range largely covers the age range for primary and middle school; (2) we report factors including visual health internal influence mechanism; and (3) examine related spatial environmental variables as part of outcomes. We exclude studies that did not sufficiently focus on any aspect of child/youth population, spatial environment, myopia or visual health. The only exception we made in this regard is if the work pertained to specific environmental variables or related issues in instances where it was not possible to focus on children's myopia and school spatial environment myopia interventions.
Of the 53 full-text sources assessed, 14 were retained for qualitative review. In order to enable translation to the school spatial environment intervention, we focused on 39 sources that are empirical studies or reviews of empirical work, and which pertained to school environmental variables that could potentially be used by architecture designers (Figure 1).

Data Extraction and Analysis
We qualitatively analyzed literature sources to identify study types and designs, sample characteristics, approaches and measures, and key findings. We then engaged in an iterative process of summarizing and synthesizing the findings, assessing relative strengths of evidence in order to construct the role of school spatial environment among visual health sufficiently, and considering how we might best translate evidence to a structure that would be of practical use to school designers-this would then help designers to undertake school design that would promote visual health.
We rated individual studies' strength of evidence by referring to research designs and the relationship with the school spatial environment by referring to 3 levels, specifically strong, moderate and preliminary.

•
Strong evidence came from longitudinal cluster randomized or cluster matched controlled trials that were conducted in school environments. These contained obvious built environmental elements and minor behaviors and could be directly oriented to architectural design. • Moderate evidence came from longitudinal approaches with smaller, single-site samples and a comparison or control group. These included placing the surrounding environment or behavior in a social context, and this served to indirectly orientate architectural design.
• Preliminary evidence first came from case studies related to visual health and then also from medical or genetic research where the associated pathogenic factors are difficult to regulate or modify-this played an indirect but fundamental role in guiding architecture design.

Data Extraction and Analysis
We qualitatively analyzed literature sources to identify study types and desig sample characteristics, approaches and measures, and key findings. We then engaged an iterative process of summarizing and synthesizing the findings, assessing relati strengths of evidence in order to construct the role of school spatial environment amo Correlates and causal factors of visual health engaged by these studies were wideranging, and in a few cases produced inconsistent results. We therefore discuss the strength of evidence for the identified school spatial environmental variables by referring to their overall support in applicable studies.
Once the relative strength of the evidence is assessed, we re-conceptualized these relevant variables into spatially-oriented design domains that were developed by referring to designers' work and decision processes. In undertaking this work, we consider core principles that apply when empirical research does not explicitly or concretely inform needed design knowledge. We also design best practice and theory-based pathways to impact that can be considered as testable hypotheses.

Characteristics of the Included Articles
Many factors may lead to myopia. We identified 53 empirical studies and literature reviews that addressed aspects related to school spatial environment and minors' visual health-these consisted of 32 (60%) longitudinal designs, 10 (18%) cross-sectional studies, 14 (26%) reviews and one case study (1.8%).
Of the longitudinal measures, six are cluster randomized trials, five are controlled studies, and 24 consisted of within-subject comparisons without an optimized or longitudinal control group. Longitudinal study sample sizes ranged from 102 to 33,355 individuals. Twenty-one studies of self or parent-completed questionnaires were subject to metaanalyses, and this made it possible to construct the independent and explanatory built environmental variables. Visual health is objectively measured with an instrumental method in 18 studies that include several types of refraction with cycloplegic and ocular biometry, cycloplegic autorefraction and axial length and clinical eye examination.
All cross-sectional studies used quantitative and applied statistical methods to explore related visual health environmental factors. Of these studies, 10 explored behavioral factors (including outdoor activity and near work) and seven studied family factors like living type and location and eating habits. Cross-sectional study sample sizes ranged from 264 to 43,771 individuals.
A total of 11 (79%) reviews focused on the relationship between environmental factors and visual health and addressed factors that included local population density and light environment. Two (14%) examined atropine, and the same percentage of articles (15%) examined genetic and environmental factors in relation to visual health. Most records are narrative reviews (58%), and only a few performed systematic meta-analysis (8%). The review elaborated the influence of genes and environment on visual health in detail, and six focused on the light environment. Tables 1 and 2 show the relevant research factors of visual health, the study setting location and population characteristics; in addition, it also provides a research description and provides the selected studies' outcome measures. To examine the prevalence of myopia and its related personal eye habits.
A stratified cluster sampling visual acuity (VA) test was applied three times (at baseline, 6 months and 1 year after intervention) through eye examinations and a questionnaire.
Taiwanese children in Grades 4-6 To explore the effect of family, activity, and school factors on myopia risk and severity. To examine the prevalence of myopia and its related personal eye habits among junior high school students and to explore stage-specific myopia prevention behaviors.
stratified random cluster sampling 2 289 students online and 2 570 students on-site with questionnaire July 2020 outdoor time [25] Canada 166 children To determine the prevalence of myopia, proportion of uncorrected myopia and pertinent environmental factors among children.
Refraction with cycloplegia and ocular biometry were measured in children from two age groups. Parents completed a questionnaire One year 2014-2015 long-term excessive use eye, outdoor activities and gender [26] China Primary students (11,246) junior students (3673) senior students (4220) To explore the situation and the affect factors of myopia and scientificalness and effectiveness of eye exercises. To quantitatively assess the role of heredity and environmental factors in myopia. The family was referred to in order to establish an environmental and genetic index.
A pedigree analysis with one child (university student), father, and mother; in a multiple regression analysis; 114 pedigree; milies were used as a control group.
Unspecified near work, social-constructed gender difference on myopia [29]. Case-control study self-questionnaire and parents questionnaire One-year To assess whether a change in myopia related oculometric parameters was associated with indoors and outdoors activity.
One-year follow-up the longitudinal school-based study one-year gender, grade, near work and parental myopia [47] Guangzhou, China 3055 students of grades 1-6 and grades 7-9 To estimate the prevalence of myopia and to explore the factors that potentially contribute to myopia.
Refractive error measurements and a structured questionnaire data In December 2014 environment, time of near work, heredity, nationality, grade, and outdoor time [48] Guizhou, China 7272 qualified students of 8413 students To investigate the prevalence of myopia among urban and rural students in the Xingyi city of Guizhou province and to analyze the influencing factors.
Visual acuity, refractive examination, were examined among all the subjects, and a questionnaire was analyzed by using logistic regression.  The precise biological mechanisms through which the environment influences ocular refraction are a matter of debate. Outdoors time is an important factor in the prevention of myopia.
Systematic review, meta-analysis exposure to outdoor ambient daylight [52] Indian Increasing time in outdoor environment could counteract the rising prevalence of myopia in Indian school-going children 29 The article describes the current myopia scenario in India; identifies ways to tackle the future epidemic. It considers the importance of day light exposure in counteracting myopia and reported possible public health policies for initiation at a school level that could potentially help in myopia prevention and control its progression.
Narrative review ow-concentration atropine and outdoor time [53] America Myopia Control: A Review 53 Antimuscarinic agents include pirenzepine and atropine, low-concentration atropine and outdoor time have been shown to reduce the likelihood of myopia onset.
Narrative review educational pressure(read for long hours), outdoor time, low-dose atropine and orthokeratology [3] Asia Stopping the rise of myopia in Asia 160 More time outdoors and low-dose atropine show best effect in reducing the incidence of myopia and delaying its the onset. Low-dose atropine, orthokeratology, executive prismatic bifocals, and multifocal soft contact lenses have been shown to be remarkably effective in slowing myopia progression.  The study identifies the education environment as the primary factor that causes the onset and progression of student myopia, the paper fully recognizes the scientific rationality of and the specific role served by education-medicine synergy in student myopia prevention and control.
Narrative review near work (time and intensity) and myopia, and its possible mechanisms [10]  To systematically research association between gene-environment interaction and the myopia/spherical equivalent.

Description of the Visual Health Loop
In order to better understand the relationship between school spatial environment and minors' visual health, this study draws on established research to construct a loop diagram that describes the inner mechanism.
Ever since myopia research began, several decades of research have addressed genetic inheritance; however, the related population genes have not changed significantly. Meanwhile, the number of people with myopia has increased greatly as a result of changes in the physical living environment and lifestyle in recent years, and this indicates that environment may play a decisive role [33,40] (p. 8). Myopia is not only affected by genetic factors, but also by the biological hormone regulation of the internal physiological mechanism [62,63] (p. 13).
Furthermore, there is a close relationship between human behavior under the influence of the external environment and biological reaction. For instance, outdoor exposure could boost the secretion of dopamine in minor retinas, and this could regulate eye development and promote visual health [64]. Concurrently, the short-wavelength blue light of sunlight, namely the spectral component of 446-477 nm, is much more abundant in daylight than artificial lighting, and its substance is related to the secretion of melatonin, which can promote circadian rhythm, assist the development of the eyeball, and improve sleep [65]. Behaviors that are subject to different environmental influences will further affect the internal hormone regulation, and this clearly indicates that myopia is a disease caused by the interaction between genetic and environmental factors. Closer inspection shows it is more related to the surrounding environment of minors, after force majeure such as heredity are excluded. Similarly, key influencing factors, such as the minors getting out and enjoying outdoor activities, and the possession of a comfortable near work environment are closely connected to spatial environment characters. Hormones act as the inner core influencing mechanism, and the environment could be artificially designed externally and could influence visual behavior further. In being subject to the influence of the social environment and educational mode, near work behavior and outdoor exposure behavior are the main types of visual health behavior that are related to the spatial environment. Our study aims to provide visual health environment from the perspective of school spatial environment, through the conclusion of biological mechanism research to guide the architecture design.
These related literatures addressed a broad array of macro to micro-level school environmental characteristics and relationships and considered them in relation to a range of visual health-related measures. In drawing on the literature research, we set the loop picture to describe the ways in which related factors influence visual health ( Figure 2).

Medical Related Research
• genetic inheritance (1) Parents myopia Myopia prevalence is significantly higher among children whose parents both have myopia. The greater the severity of parental myopia, the higher the risk of myopia [23,24,39,43,66,67] (p. 6,8,9). Minors' eye AL (ocular axial length) values may also have been affected by parental genetics [62]. Parental myopia is also thought to be a symbol of genetic and shared family environmental exposure, and parents with myopia are more likely to create an environment that creates visual fatigue, including more intensive education or less time out-doors [34,63] (p. 8); however, gene-environment interactions are not well understood.
(2) Susceptibility gene The minor's gender affects the probability of myopia, which means it is more probable that girls will develop myopia during adolescence [23,24,68] (p. 6). Medical gene studies have found that at least 10 genes are associated with early-onset changes in refractive error [69]. Additionally, some gene mutations can lead to myopia or other refractive error phenotypes [70].

Medical Related Research
• genetic inheritance (1) Parents myopia Myopia prevalence is significantly higher among children whose parents both have myopia. The greater the severity of parental myopia, the higher the risk of myopia [23,24,39,43,66,67] (p. 6,8,9). Minors' eye AL (ocular axial length) values may also have been affected by parental genetics [62]. Parental myopia is also thought to be a symbol of genetic and shared family environmental exposure, and parents with myopia are more likely to create an environment that creates visual fatigue, including more intensive education or less time out-doors [34,63] (p. 8); however, gene-environment interactions are not well understood.
(2) Susceptibility gene The minor's gender affects the probability of myopia, which means it is more probable that girls will develop myopia during adolescence [23,24,68] (p. 6). Medical gene studies have found that at least 10 genes are associated with early-onset changes in refractive error [69]. Additionally, some gene mutations can lead to myopia or other refractive error phenotypes [70].
The risk of myopia developing varies in accordance with age-it progresses most rapidly between the ages of six and seven and slows down after the ages of 11 and 12 [23,33,48,71] (p. 6,8,9).
(3) Atropine The risk of myopia developing varies in accordance with age-it progresses most rapidly between the ages of six and seven and slows down after the ages of 11 and 12 [23,33,48,71] (p. 6,8,9).
(3) Atropine With regard to drug treatment related to Optometry, it has been found that antimuscarinic drugs, such as the most widely studied atropine, slow the progression of myopia; however, some minors do not respond to it, and there has been no large-scale popularization or application [72].
• peripheral refractive error (1) peripheral refraction The central refractive error is determined by the foveal region on the visual axis, although peripheral retinal and other regions also play an important role in eye growth [73]. The degree of peripheral hyperopia varies among different heritage groups [74,75], and minors with myopia have greater peripheral relative hyperopia [76]. Both emmetropic and hyperopic children had peripheral relative myopia at all eccentric points [77]. Peripheral hyperopia co-occurs with prolonged myopia and determines the myopia patients' eyeball shape. In contrast, a longitudinal study found that baseline peripheral refraction did not predict nor influence the development of myopia [78].
(2) physiological hormone regulation Recent medical studies found that outdoor exposure could promote the secretion of dopamine in minors' retina and could regulate eye development and promote visual health [79]. Meanwhile, the short-wavelength blue light of sunlight, namely the spectral components of 446-477 nm, is much more abundant in daylight than artificial lighting. Additionally, this substance is related to the secretion of melatonin, which can promote the circadian rhythm and eye development, and improve sleep quality [65].

Environment Related Studies
• educational environment The difference in education level largely determines the difference in the probability and degree of myopia and intelligence test scores [80]. Education level was also positively correlated with AL length, which is an important judging factor for myopia [81,82]. Meanwhile, early intensive education is associated with higher prevalence of myopia than the other factors [83].Education level is usually measured by years of formal education or academic achievement, and is also highly correlated with near work time. Education level may therefore be a substitute factor for proximity work and number among the influencing factors of myopia [34,45,84] (p. 8,9). The relationship between education and myopia may also reflect the common inheritance of intelligence and refraction, which enrich the method of myopia researches.
When the traditional educational mode turns to multimedia teaching, the old instructional design criteria are no longer suitable. School type [32] (p. 8), desk lighting [40] (p. 8), sitting location in classroom, screening time [19,20,32,33] (p. 6,8) and multimedia teaching under daylight conditions [16] (p. 5), will also influence minors' visual health through near work. Classroom unit spatial design should also be changed to adapt to the current education model, in order to provide more visual health environment.
• spatial environment The development of myopia is also related to geographical location, and urban dwellers have a higher risk of visual impairment and blindness than those in rural areas, including in China [42] (p. 9), [85], Ghana [86] and Australia [44], this may be caused by differences in lifestyle, urbanization, school type and demographic characteristics [22,[32][33][34]47,51] (p. 6,8,9). Meantime, different geographical areas have various climacteric characteristics that are related to differences of daylight environment, this can be seen in Istanbul [87], Chongqing, Lasa [88], London, Chicago, Dubai and Bangkok and so on. London, Chicago, Dubai and Bangkok have different fenestration parameters in order to ensure the effective use of daylighting, due to local daylight performance [89]. Outdoor activities in China's rural area have a weak protective effect on visual health, and this may be because minors in rural areas have a lower genetic susceptibility to myopia; in addition, environmental factors may be an important reason for visual impairment [90]. Additionally, the indoor environment, like plants, can also influence the relief of visual fatigue [27] (p. 7). After controlling for other interfering factors, we observe that family living environment is an influential factor for minors' myopia [28,29] (p. 7). Living on a lower floor allows more time to go outdoors, which is a visual health protective factor. While there is less research on the relationship between the environment and visual health, physical environment has been found to play an empirical role in the overall mechanism [36] and influence behavioral choices [91], which provides support for architecture design Outdoor daylight exposure could protect visual health to a certain extent and delay the development of myopia, and this is because outdoor time is an important protective factor [15,17,21,23,24,46,52,55,92] (p. 5, 6,[9][10][11]. Minors who spent less time outdoors and more time near work had a higher rate of myopia, and those who spent less time on near work had a lower rate [26,27,35,36,38,[93][94][95] (p. 7,8,16), which indicated increased outdoor time as a solution for myopia, and provided architecture design direction. Similarly, animal experiments have also found that a less bright environment can increase the probability of myopia [96].
However, the biological mechanism of the association between outdoor exposure and myopia remains unclear. It has been hypothesized that higher outdoor brightness increases field depth and reduces image blur, and that light stimulation induces dopamine production in the retina and adjusts eye growth [95]. It has also been hypothesized that the spectral component of daylight is an important visual health factor [97]. Studies have also identified the non-visual effects of light and Healthy Circadian Lighting, namely that light has an important impact on the human body's circadian system. Non-visual photoreceptor cells (ipRGC) transmit light signals to the brain's suprachiasmatic nucleus (SCN) and body clock and regulate the secretion of melatonin and cortisol (which are closely related to circadian rhythm) [98]. Both these explain how outdoor time could protect visual health.

Behavior Related Studies
• negative behaviors related to visual health Near work is usually defined as long or close reading by minors. Children who read continuously within 30 cm for more than 30 min tend to develop myopia [99]. Meanwhile, children who read more than two hours per day and more than two books per week are more likely to be nearsighted [13,30,35,38,49,50,55,99] (p. 5,7-11). It has also been found that the light environment of near work will influence visual health [14] (p. 5). Meanwhile, outdoor activities can protect visual health [100].
Some studies have also found there is no association between close visual work and vision-related health risks [101,102]. Most myopia and near work are cross-sectional and cannot examine the temporal relationship. Those who have myopia may wear glasses and find it more difficult to participate in sports tasks, which results in lower levels of physical activity [103]. Parents also filled in most of the information about minors' near work and outdoor time, which led to recall bias. In the future, more accurate and standard methods should be used to quantify the near work modifiable variables in near work, such as reading posture, rest during reading and appropriate lighting. These should be studied in order to promote health [104], and this could change e and adjust behavior in accordance with spatial environment design. The increased burden of school learning plays an important role in the high prevalence of myopia and visual impairment. This may be due to intensive near work, which increases the risk of myopia [33,105]. Bad eye habits and electronic devices are also risk factors [106,107]. Family eating habits and BMI risk factors [43] (p. 9), including changing from a Japanese to a Western diet, may increase the risk of myopia [18,19,108] (p. 5). Additionally, these factors could be improved in other ways, like social management policy and media guidance. This can help to produce positive behaviors related to visual health positive behaviors related to visual health.
• positive behaviors related to visual health Resting behaviors (including night's sleep and short rest) have been associated with the probability of minors' myopia [25,50] (p. 7), that could protect visual health. The level of myopia is significantly associated with night sleep, and not with the duration of total noon and evening sleep [37,54,100] (p. 8,11). With regard to the biological mechanism, the circadian rhythm of human sleep mainly depends on the joint regulation of melatonin and dopamine, when melatonin combines with the corresponding eye receptors to jointly regulate the eye's development [66] (p. 14). Short rests, meanwhile, have been found to reduce fatigue [103]. Some animal experiments have also demonstrated that the circadian rhythm disorder will increase the risk of myopia [109]. Change of minors' daily waking and sleeping time is a simple measure that can be introduced to restrain myopia [110].
Eye exercises organized by schools have a certain protective effect on myopia [44,111] (p. 9). In addition appropriate myopia correction can also protect visual health, further reduce visual damage and slow myopia progression [112]. Parents' awareness of refractive error also determines the proportion of minors' myopia correction, and this further affects visual health [53,113] (p. 11).

Visual Health Guidelines for School Architecture
In referring to the loop diagram's logical chain, we see that it is both plausible and likely that the school spatial environment will impact on minors' visual behavior. However, few review studies have discussed associations with minors' visual health. We combined the relevant studies and summarized the value of school spatial environment for systematic myopia intervention. In the causal loop diagrams of visual health, school layout is shown to be closely related to the indoor light environment through effects on near work behavior; in addition, spatial environment greatly influences minors' outdoor times via hormone regulation and physiological processes in daylight. The natural elements could also relieve visual fatigue, and this applies both indoors and outdoors. These studies use direct and indirect routes to combine visual health promotion and school design.
Usually, visual health is always connected to near work behavior that is related to indoor light environment in school. Additionally, school layout, windows' scale, buildings' orientation and so on are the main influences. On the basis of the loop diagram logical chain, we therefore propose that light environment changes due to technology also need to be taken into account. For the most part, visual health promotion has not only considered physical school environment variables but has provided general support to providing minors with adequate outdoor activities. For example, diverse playgrounds, convenient outdoor access, various types of activity equipment and varied travel experience all show how this can be achieved. While the specific relationship between school spatial environment and visual health has not been precisely defined, it has been demonstrated that the school environment promotes visual health opportunities. Minors' outdoors activities at school have decreased dramatically over preceding decades, and this is why the importance of outdoors time as a way of improving visual health has been increasingly reiterated. Unfortunately, many schools and surrounding environments have not been conducive to outdoor activities. In addition, minors who lived in cities were more prone to myopia than rural counterparts, and in this regard it was significant that urban schoolchildren enjoyed substantially less school outdoor time. We identified empirical studies and literature reviews that engaged school spatial environmental design and minors' visual health. In contrast to many of the reviews that identified advantages and difficulties in the promotion of visual health, including changes to the physical environment, this review was instead focused on the school's spatial 'designed' environment.
The complex causal pathways between school spatial environmental factors and minors' visual behaviors are still unclear. However, in acknowledging the ongoing need to improve visual health behaviors across numerous minor populations, schools have introduced and promoted design guidelines (see Table 3). They are summarized on the basis of the literature review and relevance analysis. improve visual health behaviors across numerous minor populations, schools have introduced and promoted design guidelines (see Table 3). They are summarized on the basis of the literature review and relevance analysis. improve visual health behaviors across numerous minor populations, schools have introduced and promoted design guidelines (see Table 3). They are summarized on the basis of the literature review and relevance analysis.  ✰ Enhance the diversification and interesting of activity areas [117,129] [122] ✰ ✰ Consider the merging of different spatial levels to enhance openness and transparency [121] ○ (a) selection of background wall material (b) selection of background wall color (c) selection of background wall's material and color collocation (d) selection of indoor green configuration Combine daylight and the external landscape to utilize view window to provide visual connection to the outdoors [122] Improve environmental adaptability for visual work tasks Optimize the scale of teaching unit according to the light spatial distribution and visual distance of multimedia teaching [122,123]  improve visual health behaviors across numerous minor populations, schools have introduced and promoted design guidelines (see Table 3). They are summarized on the basis of the literature review and relevance analysis. improve visual health behaviors across numerous minor populations, schools have introduced and promoted design guidelines (see Table 3). They are summarized on the basis of the literature review and relevance analysis. improve visual health behaviors across numerous minor populations, schools have introduced and promoted design guidelines (see Table 3). They are summarized on the basis of the literature review and relevance analysis. improve visual health behaviors across numerous minor populations, schools have introduced and promoted design guidelines (see Table 3). They are summarized on the basis of the literature review and relevance analysis. improve visual health behaviors across numerous minor populations, schools have introduced and promoted design guidelines (see Table 3). They are summarized on the basis of the literature review and relevance analysis. improve visual health behaviors across numerous minor populations, schools have introduced and promoted design guidelines (see Table 3). They are summarized on the basis of the literature review and relevance analysis. improve visual health behaviors across numerous minor populations, schools have introduced and promoted design guidelines (see Table 3). They are summarized on the basis of the literature review and relevance analysis. improve visual health behaviors across numerous minor populations, schools have introduced and promoted design guidelines (see Table 3). They are summarized on the basis of the literature review and relevance analysis.  Improve the adaptability of outdoor facilities Consider indoor and outdoor activity places to suit minors' age and behavior patterns [117] Make interactive landscape experiences more themed and flat [117] Evidence Rating Key: Substantial Evidence = longitudinal cluster randomized or cluster matched studies directly oriented to architectural design strategy and visual health.
ng the windows construction technology [114,115]  ✰ ✰ sider the merging of different spatial levels to ence openness and transparency [121] ○ Emerging Evidence = longitudinal approaches with smaller, single-site samples and a comparison or control group supporting the strategy exists, but is indirectly orientate architectural design. Best Practice = theoretical support and/or practice-based experiential support for the strategy, but based on circumstantial evidence.

Discussion
(1) Benefits of other dimensions The universality of the myopia problem and the vital practical significance of our re-search suggests that guidelines could be applied in other areas to promote health. For example, introducing biophilic design elements into the office, such as daylight and greenery, could improve human well-being, performance, creativity and health [133]. In addition, developing healthy circadian lighting for inpatient ward could compensate for the lack of daylight; considering community walking/cycling and public transportation; and encouraging good eating habits could also promote health.
Meanwhile, the role of the school spatial environment certainly has multiple health benefits, and this is because of the complex causal pathways between visual health and human behaviors. For example, outdoor time could increase physical activity and promote optimal functioning [134]. Other studies have shown that it can address other health problems and contribute various health benefits (including promote physical fitness) [135] and improve academic achievement [136][137][138].
(2) Benefits under the life dimension The diopter between minors' hyperopia and emmetropia is regarded as the regulatory reserve. The newborn's binocular hyperopia gradually tends to be normal along with growth. [139]. If the minors' eye axis length is prematurely developed to 24 mm, then the adjustment reserve is exhausted in advance, and they are more likely to develop myopia. It has been hypothesized that screen exposure in early life may be related to the occurrence of myopia in preschool minors [140]. Unhealthy minor behavior, including excessive reliance on electronic screens, spending too long in the artificial lighting environment and limited outdoor activities are leading to premature minor consumed hyperopia reserves and even myopia. The early detection of hyperopia reserve deficiency and timely intervention both have a key role to play in protecting minors' vision [141]. Different architectural types could link all the life stages, and this could help to control the progress of myopia, which means the prevention and control of myopia can be classified into different targets based on stages of visual health. For instance, it is possible to maintain visual health situation, and delay the myopia process after getting myopia. It is of the utmost practical importance to design architectural spatial environment that promotes visual health.
In the myopic loop diagram, the visual health mechanism is diversified. Our review only discusses the impact of the school spatial environment on visual health, and it does not therefore engage other factors, such as social management and medical treatment that could benefit the protection of visual health.
(3) Benefits of society dimension As architectural designers, we should consider the surrounding environment and the housing type with the aim of providing a visually healthier living space [142]. Of course, it is also essential to take into account other family-related influencing factors, like eating habits and transportation modes. Additionally, social constructs that could impact gender differences also require more discussion and exploration [24].
There are substantial differences in education modes across different regions and countries, and this includes America's outdoor campus with Richard Noitra's natural school. However, Chinese research of myopia and the construction of educational buildings is still at a relatively early stage, and is still, taking into account the daylight environment, concerned with traditional forms and structures. At the same time, the construction of short time with high population density has greatly influenced the Chinese educational mode, with result that the majority are enrolled in large classes and that minors are mostly taught in fixed classrooms and encouraged to stay indoors during breaks. This contrasts with the walking classes of America, which promote activity and increased daylight exposure between classes. This is just one point of possible reference for the future development of the Chinese educational model. Others should be considered to maximize health promotion.

Conclusions
This study engages with the school spatial environment design process to show how changes in school spatial environments can promote visual health. It then builds on this insight to put forward feasible strategies that could be used to guide school design towards desirable visual health outcome. These include the accurate and controllable environment of near work behavior, which operates in accordance with various educational mode requirements and the active design of the environment of outdoor exposure behavior (see Table 3). However, shortcomings in the medical and empirical research evidence base will need to be addressed and overcome if progress is to be made in this regard. In addition, while the guidelines seek to focus school spatial environmental design decisions on minors' visual health, they do not yet include a "formula" or identify specific design strategies that will meet building codes; in addition, they also currently omit many details, including spatial form and material specifications.

Conflicts of Interest:
The authors declare no conflict of interest.