Preparing Your Practice for the Myopia Control Stampede
As myopia control evidence and awareness build, it is clear that we need to act now. Are you ready?
By Kate Gifford, BAppSc(Optom)Hons, GCOT, FBCLA, FIACLE, FCCLSA, FAAO
Mounting evidence shows the increased frequency of myopia in many populations around the world and across ethnicities. In Australia, the rate of myopia in 12-year-old children of European Caucasian descent doubled from 2005 to 2011, and more than 50% of Australian children of East Asian origin are myopic (French et al, 2013). The same age group in urban Britain demonstrates an almost 30% incidence of myopia (Logan et al, 2011). In Americans aged 12 to 54 years, the prevalence of myopia has almost doubled to more than 40% in the past 30 years (Vitale et al, 2009), and in some Asian countries, 80% to 90% of the population are myopic by the time they reach adulthood (Lin et al, 2004; Jung et al, 2012).
By 2050, it is predicted that half of the world’s population—5 billion people—will be myopic, with nearly 1 billion at risk of myopia-related ocular pathology (Holden et al, 2015). The late Prof. Brien Holden was a champion of ensuring that myopia is on the world health agenda; high myopia is strongly linked to a higher risk of cataracts, retinal detachment, and myopic maculopathy (Flitcroft, 2012). Increasing rates of vision impairment and blindness due to the latter are already evident in Asian countries (Iwase et al, 2006; Wu et al, 2011).
Why Getting Prepared Is So Important
Healthcare decision-making requires an accurate prediction of outcomes and their impact, which is challenged by lack of familiarity with the circumstance. Healthy people can mispredict the impact of chronic illness and disability compared to those who have existing conditions (Ubel et al, 2005). In the same way, it is difficult for the parents of pediatric myopes, and even for practitioners, to be cognizant of the long-term benefits of myopia control beyond having a lower prescription.
It is important to take myopia control seriously, however, as even 1.00D of myopia doubles the risk of myopic maculopathy (MM) and posterior subcapsular cataract (PSCC) and triples the risk of retinal detachment (RD) compared to emmetropes. At 3.00D of myopia, the risk of PSCC triples, and the risk of RD and MM is nine times that of an emmetrope. Once children reach 5.00D of myopia, they hold a five times greater risk of PSCC, a 21 times greater risk of RD, and a 40 times greater risk of MM; higher levels bring more eye-watering risks. These odds ratio risks demonstrate that there is no physiological level of myopia that could be considered “safe” in comparison to emmetropia (Flitcroft, 2012) (Table 1).
|Myopia (D)||Glaucoma||Cataract (PSCC)||Retinal detachment||Myopic maculopathy|
|–1.00 to –3.00||2.3||2.1||3.1||2.2|
|–3.00 to –5.00||3.3||3.1||9.0||9.7|
|–5.00 to –7.00||3.3||5.5||21.5||40.6|
|* summarized from Flitcroft (2012)|
An analogy can be drawn to the association between diabetes and sugar intake. While suspected and observed historically, it was unclear whether multiple factors such as obesity, sedentary behavior, consumption of other foods, aging, urbanization, and income confounded the link between sugar intake and diabetes prevalence in overall populations. However, recent data evaluating 175 countries, and controlling for each of these confounders, found a dose-dependent relationship whereby every 150kcal per person per day increase in sugar availability was associated with an increased diabetes prevalence of 1.1% (Basu et al, 2013).
Similarly, every part-millimeter increase in axial length in a myope brings an increased risk of pathology, with MM and RD odds ratio risks demonstrated as power models in reference to the level of myopia. This indicates that myopia is an important independent lifelong risk factor for ocular disease, being the dominant factor in MM and RD, and it is second to age with respect to cataracts and glaucoma (Flitcroft, 2012).
Parents will be driven to seek myopia control strategies because they feel it is “wrong” for their child’s refraction to increase every few to several months, but they won’t necessarily have the sense of why. As practitioners, it’s important that we acknowledge the concerns of these parents by explaining why myopia control matters for their child’s lifelong eye health. Conversely, being inactive in myopia control will cause informed parents to question your management; there is a wealth of research on epidemiology and management strategies to attest to myopia control as an evidence-based best practice.
Time to Act
The younger that children become myopic, the faster they will progress—children 7 years of age progress by at least 1.00D per year, with this halving by age 11 to 12 years (Donovan et al, 2012). Instituting a myopia control strategy as early as possible is an evidence-based practice.
However, myopia control is not just applicable to myopes; exhibiting less than 0.50D of manifest hyperopia at age 6 to 7 years is the most significant risk factor for future myopia, independent of family history and visual environment (Zadnik et al, 2015). Moreover, the fastest rate of refractive change in myopic children occurs in the year prior to onset (Mutti et al, 2007), so children who are less hyperopic than age normal should be closely monitored, especially if concurrent risk factors of family history or binocular vision status are evident.
Determining Who’s at Risk Table 2 summarizes risk factors for development and/or progression of pediatric myopia. Children who have one myopic parent have a three-fold risk of myopia development compared to their peers who do not have this family history; two myopic parents doubles this risk again (Jones et al, 2007). Risk factors for progression to high myopia, and hence higher risk of future ocular pathology, include having two myopic parents and onset at age 6 to 7 years, which increases risk 6.6 times compared to older (11 years) age of onset independent of ethnicity and gender (Gwiazda et al, 2007). Children who have two myopic parents are the fastest progressors in single-vision spectacle and atropine corrections, and children who have one myopic parent progress less compared to the former but more compared to children who do not have such family history (Kurtz et al, 2007; Loh et al, 2015).
One myopic parent – three times greater risk of myopia development.
|Time spent outdoors||Less than 1.6 hours per day increases risk two- to three-fold (see below).|
|Time spent on near work||More than 3 hours per day (excepting school time) – only when co-factored with low time spent outdoors.|
|Age of onset||Younger (6 to 7 years) versus older (11 years) onset gives a 6.6 times risk of progression to high myopia.|
|Current refraction||Less than +0.50D at age 6 to 7 years is a risk for myopia development.
The fastest refractive change occurs in the year prior to myopia onset.
|Ethnicity||Asian ethnicity may be linked to faster progression, with conjecture.
The risk factors of current refraction, time spent outdoors and family history risk of high myopia are independent of ethnicity.
|Binocular vision characteristics||Increased accommodative lag and higher AC/A ratio may predict myopia onset.
The presence of accommodative lag and esophoria predicts faster myopia progression as well as more favorable responses to myopia control strategies.
|* References in text|
On the positive side, a strong family history of myopia has resulted in stronger treatment effects in studies investigating efficacy of progressive and novel spectacle lens designs for myopia control (Kurtz et al, 2007; Sankaridurg et al, 2010). Asian ethnicity has been linked to faster myopia progression in the past (Hyman et al, 2005; Donovan et al, 2012), but more recent data indicates that progression in Asian and Caucasian children may be similar (French et al, 2013).
Time spent on near-work activities has long been considered a risk for myopia development and progression; however, when controlled for parental myopia and time spent outdoors, it does not hold as an independent risk factor (Jones et al, 2007; Rose et al, 2008). Increased outdoor activity, regardless of the type of activity, with low and moderate levels of near work can protect against myopia development, regardless of ethnicity, gender, parental myopia, employment, and education; this relationship has been affirmed in Australian, American, and Asian studies (Jones et al, 2007; Rose et al, 2008; Dirani et al, 2009). Children with low outdoor activity (0 to 1.6 hours per day) and high hours of out-of-school near work (>3 hours per day) at age 12 have a two- to three-fold higher risk for myopia compared to their peers with high outdoor activity (>2.8 hours per day) and low near work outside of school (0 to 2 hours per day) (Rose et al, 2008).
Further risk factors include the presence of esophoria, accommodative lag, and higher accommodative convergence (AC/A ratio) at near. Pre-myopes show a higher accommodative lag compared to their peers who do not become myopic, although the correlation is stronger after myopia onset, indicating that this may be a feature rather than a cause of myopia (Mutti et al, 2006). Children who have higher response AC/A ratios have a more than 20 times increased risk of myopia development within one year (Mutti et al, 2000). In myopia control studies of progressive addition spectacle lenses (PALs), children with esophoria in single-vision spectacle control groups progressed more quickly (Yang et al, 2009), and children with a larger baseline accommodative lag in the PALs groups showed statistically greater treatment effect (Gwiazda et al, 2003).
Fitting bifocal soft contact lenses to myopic children who had esophoria at near, in which the add was chosen to neutralize the associated phoria, resulted in a 70% reduction in axial elongation over 12 months compared to single-vision soft contact lens-wearing controls (Aller et al, 2016). Children with lower baseline accommodative amplitude have a greater myopia control response to orthokeratology contact lens wear compared to normal accommodators (Zhu et al, 2014).
Myopia has long been associated with inaccurate and insufficient accommodative behavior at near and with increased accommodative convergence in comparison to emmetropes (Drobe and de Saint-André, 1995; Gwiazda et al, 1995; Charman, 1999; Mutti et al, 2000; Gwiazda et al, 2005); detecting these conditions in both at-risk emmetropes and myopic children can reveal the picture of myopia progression risk.
When to Start Initiating a myopia management strategy for pediatric patients should ideally commence before they become myopic, in view of the risk factors described above. At-risk emmetropes may exhibit any or all of the following: one or two myopic parents, lower than age-normal hyperopia, accommodative lag, and esophoria at near.
For children who are already myopic, having two myopic parents is predictive of both high myopia and potential positive response to a myopia-controlling strategy. Depending on a child’s characteristics and capability, myopic refractive error can be corrected and actively managed using spectacles, contact lenses, pharmacological treatments, and visual environment modifications.
How to Manage Myopia
At-risk emmetropes presumably have no refractive error to correct, but in view of the risk factors described, you can start by providing advice on visual environment and by ameliorating their esophoria and accommodative lag at near. The simplest treatment for the latter involves prescribing a near add for use during school hours and for near work tasks at home, usually in the form of bifocal or progressive addition spectacle lenses to neutralize the fixation disparity and bring accommodative lag at near back within the normal range of +0.50D to +0.75D (Scheiman and Wick, 1994; Evans, 2007). At least 90 minutes spent outdoors per day, along with limiting homework and leisure near-work activities to less than three hours after school, will reduce myopia risk. This is the limit of evidence-based practice at present.
Treatment options for progressing myopes include PAL, bifocal, and novel peripheral defocus spectacle lenses; soft bifocal or multifocal contact lenses; orthokeratology; and atropine (Table 3). It is important to note that standard single-vision spectacles, GP contact lenses, and soft contact lenses do not provide any myopia control benefit (Katz et al, 2003; Walline et al, 2004; Walline et al, 2008), and hence their prescription for progressing myopes is not an evidence-based practice.
|Treatment||Duration of studies||Reduction in axial elongation|
|Standard spherical GPs and soft contact lenses||2 to 3 years||0% to 5%
(Katz et al, 2003; Walline et al, 2004; Walline et al, 2008)
|Atropine||2 to 5 years (mode 2 years)||30% to 77%
(Chua et al, 2006; Tong et al, 2009; Chia et al, 2012; Chia et al, 2016)
|Atropine rebound effect||1 year||1% atropine reduces to a 30% total control effect (Tong et al, 2009) Lower rebound frequency with 0.01% atropine compared to with higher concentrations (Chia et al, 2016)|
|Spectacles: PAL, bifocal, and novel lens designs||1 to 2 years||12% to 55%
(Edwards et al, 2002; Gwiazda et al, 2003; Yang et al, 2009; Cheng et al, 2010; Sankaridurg et al, 2010)
|Soft contact lenses: bifocal and multifocal||6 to 12 months||29% to 69%
(Anstice and Phillips, 2011; Sankaridurg et al, 2011; Walline et al, 2013; Aller et al, 2016)
|Orthokeratology||1 to 5 years (mode 2 years)||32% to 100% (meta-analysis 45%)
(Cho et al, 2005; Walline et al, 2009; Kakita et al, 2011; Cho and Cheung, 2012; Hiraoka et al, 2012; Santodomingo-Rubido et al, 2012; Charm and Cho, 2013; Si et al, 2015; Sun et al, 2015; Swarbrick et al, 2015)
Despite this being revealed in research around a decade ago on average, it is concerning that a recent survey of myopia control attitudes and strategies in clinical practice, undertaken across a dozen countries with almost 1,000 respondents, revealed that most practitioners (67% ± 37%) still prescribe single-vision spectacles or contact lenses as the primary mode of correction for myopic patients. Practitioners acknowledged that single-vision spectacles and undercorrection of myopia were least effective for myopia control, but cited increased cost, inadequate information, and unpredictable outcomes as justifications for what is non-evidenced-based management of progressing pediatric myopia (Wolffsohn et al, 2016).
The increased cost may include both the prescribed corrections and chair time. Contact lens corrections have garnered the greatest volume of scientific support, and practitioners may be concerned about the time investment in pediatric contact lens fitting; however, children (8 to 12 years) take only 15 minutes more on average to fit compared to teens (13 to 17 years), with most of this occurring in contact lens handling instruction (Walline et al, 2007).
Preparing your practice for myopia control includes considering patient flow. Because you will be seeing these patients more often and for more costly contact lens corrections, implementing extended payment systems may be helpful. There is no doubt that myopia is a lifelong cost burden, being around $709 per person per year (Zheng et al, 2013). This pales into insignificance, however, when viewed in terms of the cost of vision impairment and blindness to affected people, their careers, and society, which is upwards of $12,000 annually per patient, increasing with the severity of the vision impairment (Köberlein et al, 2013).
A wealth of scientific data is available to help practitioners who seek to learn more about myopia control. Summaries of recent myopia control research are readily available at www.myopiacontrol.org and through practitioner communication tools at www.myopiaprofile.com. Your choice to pick up this issue of Contact Lens Spectrum and read this far is evidence of your intention to ensure evidence-based management of your progressing myopic patients.
Similarly, practitioner concerns regarding unpredictable outcomes of myopia control strategies can be resolved by both theoretical knowledge and experience. Opportunities to learn from conference proceedings have increased over recent years. The information is available; it is up to astute practitioners to access and implement it.
Putting Myopia Control into Practice
Most of our colleagues consider themselves active in myopia control, yet most still prescribe non-evidence-based corrections (Wolffsohn et al, 2016). The first step in preparing your practice is to develop your own conviction that myopia control is imperative and to determine how you will communicate this to patients and their parents.
An important message of risks and benefits must be presented to ensure that the long-term message about ocular health is not lost in the short-term concerns about cost, time, and safety (Johnson, 2014). The effectiveness of health-relevant messages depends on framing both the gains and losses and to what degree a particular health behavior is perceived as risky (Rothman and Salovey, 1997). Increasing time spent outdoors and consenting to be managed with atropine, multifocal soft lenses, or orthokeratology should be effectively framed in discussion as health-affirming choices in the short term, whereas the opposite behavior should be described in terms of lifelong increased health risk of ocular pathology.
The link between sugar and diabetes has led to economic modeling of taxing sugar-sweetened beverages (SSBs), predicting a reduction in type 2 diabetes of at least 2% and in obesity of 1% to 4% across populations (Briggs, Mytton, Madden et al, 2013; Briggs, Mytton, Kehlbacher et al, 2013; Basu et al, 2014). This evidence has resulted in the United Kingdom government announcing a tax on SSBs in their 2016 budget, with the revenue raised to be spent on primary school sports (BBC News, 2016).
Similarly, the link between environment and myopia has seen the government of Taiwan pass a law in 2015 to ban children under the age of 2 from using electronic devices and children under the age of 18 from “constantly using electronic products for a period of time that is not reasonable,” (Philips, 2015). Public health messages in Singapore encourage children to spend more time outdoors and less time playing computer and hand-held games (Dolgin, 2015).
With these burgeoning public health messages, we as practitioners should take myopia prevention and control as seriously as at-risk or diagnosed diabetics and their healthcare practitioners should consider the dose-dependent relationship of sugar and systemic pathology. Modeling has shown that application of a 33% effective myopia control strategy would result in a 73% reduction in the frequency of myopia greater than 5.00D, and a 50% efficacy would result in 90% less high myopia, with the consequent reduction in ocular pathology risk across the population (Brennan, 2012).
Translating myopia control research into practice is a multifactorial synthesis of genetic, environmental, and optical risk factors, combined with prudent application of spectacle, contact lens, and/or pharmacological corrections. Future research will hopefully develop practitioner protocols on treatment time, duration, and appropriate therapy selection based on risk analysis and capability of the individuals. Safety concerns and side effects of atropine and contact lens treatments—which are currently showing the greatest efficacy for myopia control—along with a lack of U.S. Food and Drug Administration approval for any myopia control strategy, can reduce practitioner confidence in active myopia management (Gifford and Gifford, 2016). A wealth of scientific support exists, however; so for the current and lifelong benefit of these patients, we must ensure that we are not myopic about myopia control. CLS
For references, please visit www.clspectrum.com/references and click on document #247.
A clinical optometrist, peer educator, and researcher in contact lenses, binocular vision, and myopia control, Kate Gifford has published 28 peer-reviewed and professional publications and has presented more than 60 conference lectures throughout the world. She has also received lecture, travel, or authorship honoraria from Alcon, Bausch + Lomb, Coopervision, and Johnson & Johnson.