Practical Matters in Myopia Management
With an expanding arsenal of information, myopia can be a puzzling area of care. In this second annual Review of Optometry supplement, experts offer solutions backed by science to help you manage this growing patient population.
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While the proliferation of myopia management options has grabbed our attention in recent years, public awareness surrounding basic lifestyle factors must remain front and center regarding the role optometrists play in mitigating the increasing presence of myopia in our young populations. After all, the weight of scientific evidence over the last few decades suggests that environmental factors are driving the rise in the prevalence of myopia.1 As primary eyecare providers, we have a duty of care to accurately advise our patients on which worthwhile lifestyle modifications and habits can be adopted to minimize the risk of myopia development and/or progression.
The challenge before us is twofold: First, we need to identify which lifestyle factors have been scientifically shown to be associated with myopia, and secondly, we must determine which recommendations are realistically achievable for a child in the modern age. I aim to address both points in this article by reviewing what the science currently tells us about the effect of various lifestyle factors and habits on myopia control and providing specific tips on how to advise your patients.
Outdoor Time and Natural Light
Of all the lifestyle factors that have been studied, time spent outdoors in natural light is perhaps the most widely supported by the literature as being protective against myopia onset.2-8 Many population-based studies, including randomized clinical trials, have shown the protective benefits of increased outdoor time in preventing myopia.3-7,9-12
Various theories suggest that the positive effects of outdoor time could be attributed to factors such as increased exposure to bright light and dopamine release, short-wavelength/ultraviolet light, the stimulation of vitamin D synthesis and the relatively even dioptric landscape of a typical outdoor scene, among others.7,14-17 It is worth noting that the protective benefit against myopia has been attributed to time outdoors, not the physical activity itself.13,14
|Fig. 1. Research suggests that children should aim for two hours of outdoor time per day to reduce myopia risk. All photos: Getty Images.|
When it comes to slowing down myopia progression in children who are already myopic, the results are less clear. In 2017, a systematic review of 25 studies found no association between the dosage of outdoor time and myopia progression in existing myopic eyes. On the other hand, a study from 2019 showed an association between increased outdoor time and myopic progression. In this prospective study involving children who were already myopic, spherical equivalent refraction increased over 18 months by -1.13 ± 0.6D in children whose daily outdoor time was low (0.51 ± 0.2 hours/day), -0.72 ± 0.6D for moderate (1.37 ± 0.3 hours/day) and -0.66 ± 0.5D for high (2.5 ± 0.5 hours/day).11
While there is still some debate as to the effect that outdoor time has on myopia progression, it is now clear, at the very least, that it plays a significant role in protecting against myopia onset.
Expert agreement on how much outdoor time we should recommend to our patients is still evolving, but the literature can provide some clues. A meta-analysis compiling data from multiple studies found that every additional hour of outdoor time per week equated to a reduction in myopia risk by 2%.15 Other analyses claim a one-third reduction in the risk of myopia onset by increasing outdoor time from zero to five hours/week to 14 hours/week or more.16,17
In 2021, The European Society of Ophthalmology and the International Myopia Institute (IMI) published an update plus guidance on the management of myopia and recommended a minimum of eight to 15 hours of outdoor time per week for school-aged children to gain “clinically meaningful protection from myopiagenic stimuli.”18 The most recent Facts and Findings infographic published by IMI in 2023 now recommends a minimum of two hours per day of outdoor time for the prevention of myopia onset.19
When reflecting on all the current evidence, it’s safe to say that children and their parents should be aiming for a goal of at least two hours outside or more per day for myopia prevention.
Indoor Lighting Conditions
There is credible evidence that indoor lighting levels can significantly impact myopia onset and progression. A recent multivariate logistic analysis found that time under lighting levels greater than 3000 lux produced a protective factor for myopia in Chinese students.20 Also in China, a study from 2015 showed that even a modest increase in light levels in classrooms (from 100 lux to 500 lux) provided a significant reduction in myopia onset and the rate of axial length elongation among students.21 Interestingly, this study found that before intervention, the average lux levels at the student desk across 13 randomly selected classrooms was between 74 lux (intervention group) and 98 lux (control group), falling significantly short of the recommended 300 lux in China, the US and Europe.21-23
Moreover, the type of artificial illumination used has been called into question in recent years, particularly with the rise in popularity of light-emitting diode (LED) bulbs. One study based in China examined the prevalence of myopia among young teenagers and which types of lamps they used for homework tasks. It was found that students who used LED lamps had larger myopic refractive errors and longer axial lengths when compared to students who used incandescent or fluorescent lamps.24
Myopia risk aside, the French Agency for Food, Environment and Occupational Health and Safety warns against the use of LED lights in areas frequented by children to avoid potential photochemical damages and photoreceptor loss.25 At odds with the argument against use of LED lighting is the reality of their rapid uptake in recent years, with the US Energy Information Administration reporting an increase in houses using them for all or most of their lighting from 4% in 2015 to 47% in 2020.26
Fig. 2. Near tasks, such as digital device use, have been linked to faster myopia progression.
The association between increased near work and increased rates of myopia has long been asserted, with solid evidence to support this. Several studies have shown excessive near work can increase myopia onset and progression.27–29 A three-year follow-up study in Finland found that increased time on near tasks was associated with faster progression of myopia.30 In this study, “fast” progressors spent an average of 3.5 ± 0.9 hours/day on near tasks, while “slow” progressors spent an average of 2.9 ± 0.8 hours/day. The Consortium for Refractive Error and Myopia studies have observed that educational level significantly affects the overall risk of myopia, with time spent on near work and years of education posing a greater risk than genetic factors alone.31-33 Similarly, European studies have shown that greater near work activity is a risk factor for myopia and that a higher level of education is linked to higher myopic refraction.35,34
Quantifying the exact impact of near work on risk is not straightforward, but a systematic review from 2015 found that more time spent on near tasks was associated with higher odds of becoming myopic.35 The review concluded that the odds of myopia increased by 2% for each additional “diopter hour” (a more comprehensive weighted metric based on use of visual task questionnaires that consider time and viewing distances) spent on near work per week.35
Other studies have examined more specific characteristics of near work and found that a close working distance (20cm to 25cm), a head tilt when reading, continuous reading for more than 45 minutes at a time and gripping the pen closer to the pen tip (associated with a greater probability of a head tilt) were all associated with greater odds of myopia progression.20,27,36,37
Perhaps the most common concern parents may have these days when it comes to their children’s vision is the excessive time spent on screens or digital devices. These devices constitute a significant form of near work, which we acknowledge is a risk factor for myopia. Recent studies have found significant associations between myopia and digital screen time.38,39
However, the exact contribution to risk attributed to digital screen use itself has yet to be determined, and two recent systematic reviews challenge the true independence of digital devices as a stand-alone risk factor.40,41 Such device use favors an indoor lifestyle and constitutes near work, which are two established risk factors for myopia. Both reviews concluded that digital device use may be an independent risk factor but point out that there remains a need for research with objective measures of screen time and myopia-related outcomes that investigates smart device exposure as an independent risk factor.
Regardless, there is no doubt that digital devices have become ubiquitous among children for educational purposes and entertainment. Their usage is even rampant among children of a much younger age, such as those who aren’t yet attending school. Until proven otherwise, we must proceed with caution and be wary that digital device use may contribute to the onset and progression of myopia. With this approach, the Erasmus Myopia Research Group in the Netherlands recommends complete absence of close-up screen use for children up to the age of two, a maximum of one hour per day for children up to age five and a maximum of two hours per day for children aged five to 12 years.42,43 The American Optometric Association promotes the World Health Organization’s recommendation that screen time be limited to one hour per day for children under five and no time at all for children less than one year of age.44
Fig. 3. Circadian rhythms might play a role in myopia onset and progression, studies show.
The importance of sleep for children’s health has long been acknowledged, but evidence for its role in childhood myopia is relatively new. Noting the seasonal variations and diurnal patterns of axial length and refractive error, some authors have raised the possibility of circadian rhythms playing a role in myopia onset and progression.46-47
Recent studies have produced mixed results in linking poor sleep patterns with myopia risk. A systematic review from 2023 identified 17 studies covering four main aspects of sleep—duration, quality, timing and efficiency—and their associations with myopia in children.46 Although findings were inconsistent and a causal relationship between poor sleep and myopia cannot be established from current evidence, there are implications for an association of poor sleep with childhood myopia. Specifically, insufficient sleep hours (in seven of 15 studies), poor sleep quality (in three of four studies) and late bedtime (in three of six studies) were reported to be associated with a greater degree, progression and incidence of myopia.46
|Fig. 4. A diet consisting of mostly whole foods could help minimize myopia risk.|
Much like good sleep patterns, nutritional habits may be connected to better general health outcomes. Therefore, it stands to reason that parents may want to know whether nutritional changes might improve their child’s eye health or even reduce their myopia risk.
Very little research has investigated the role that nutrition and diet may play in the development and progression of myopia in children to this point. A study from 2010 found higher saturated fat and cholesterol intake was associated with longer axial length in otherwise healthy Singapore Chinese schoolchildren.47 More recently, a review of the National Health and Nutrition Examination Survey examined data from almost 7,000 ethnically diverse Americans and found that the nutritional factors of serum vitamin D, glucose levels and caffeine intake were unrelated to refractive error or myopia. However, it found that increased insulin levels were associated with greater odds of myopia.48 It is worth noting that the age range examined in this review was 12 to 25 years, thus excluding a large proportion of the younger pediatric population where myopia often first manifests.
Nonetheless, others have made the link between higher insulin levels and myopia, with evidence that the state of hyperinsulinemia can lead to continued growth of the sclera.49,50
Given that we know that a diet rich in highly refined carbohydrates can lead to worsening glycemic control and potentially insulin resistance, it is a worthy lifestyle consideration when it comes to myopia risk minimization.
Challenges of Modern-Day Life
It’s clear that the sharp rise in myopia goes beyond genetics and that our environment is playing a driving role in its ever-increasing prevalence. Some lifestyle factors that appear to be contributors have been identified with varying degrees of scientific certainty. More time spent outdoors and less time spent indoors on near tasks have gained solid status as protective factors for reducing the risk of myopia development. Other factors such as digital device exposure, sleep patterns and nutrition all require further investigation. Still, at the very least, they currently present compelling implications for playing a part in the myopia story.
As optometrists on the front line, the question we need to ask ourselves is this: Armed with the evidence we do have, how do we realistically advise on lifestyle changes and habits that patients and their parents should adopt?
The answer must take into consideration the ways in which children today are educated, how they are entertained and even how they socialize. Most children use tablets or laptops at school, do homework on screens at home, play games or watch videos on handheld devices and even spend countless hours on social media. The convergence of so many aspects of a young person’s life plays out on their digital devices, so how realistic is it of us to advise against using them? Similarly, we don’t want to encourage our children to be less diligent with reading, writing or participating in near activities at school or with their homework.
The risk of undermining academic success or social inclusion cannot be overlooked. Of course, the reality of more near work is that it likely results in less time spent outdoors and more time spent indoors, adding two additional scenarios that encourage myopic development and even progression. For specific guidance on how to communicate lifestyle recommendations to your myopic patients and their patients while balancing these concerns, see Table 1.
The challenges of myopia prevention and control are complex and intertwined, but with good communication, creative solutions and targeted advice, we can strive for some type of balanced compromise and help minimize the risks that modifiable lifestyle factors may present.
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