How to identify and manage pre-myopes

First published: October 18, 2020
Last updated: November 11, 2024.

Imagine this clinical picture: your patient is six years old and refraction is plano. Mum is -2.00D and Dad is -4.00D. Clearly this is not a normal refractive state for a six year old, and her parental history of myopia is concerning - this is a pre-myope. How can we consistently identify pre-myopes, explain the concern to parents, and how can we best manage them?

The International Myopia Institute - Defining and Classifying Myopia report¹ clearly defines the pre-myope:

This definition is made because while reducing progression of myopia is "a central goal of myopia research... preventing the onset of myopia is an even more valuable target." Identifying pre-myopia involves recognising a situation where a child has a non-myopic refraction, but a cluster of risk factors and/or "an observed pattern of eye growth" which indicates a high risk of progression to myopia."

There are four key principles for assessing risk of myopia onset:

• Family history – one myopic parent increases risk by three-fold, while two myopic parents doubles this risk again²
• Visual environment – less than 90 minutes a day spent outdoors increases risk, especially if combined with more than 3 hours a day spent on near work activities (outside of school time)³
• Binocular vision – Children with higher accommodative convergence (AC/A) ratios, typically seen with esophoria, have an increased risk of myopia development within one year of over 20 times.⁴ Accommodative lag may also be a risk factor but there is conjecture.⁵ Intermittent exotropia has also been associated with onset of myopia.⁶
• Current refraction – the most significant risk factor of this lot for future myopia is if a child exhibits 0.50D or less of manifest hyperopia at age 6-7. This risk is independent of family history and visual environment.

In addition to this, the fastest rate of refractive change in myopic children occurs in the year prior to onset,⁸ so the child who is less hyperopic than age normal should be closely monitored, especially if concurrent risk factors are evident.

How quickly should refraction change in emmetropization? The large scale Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) Study followed almost 5,000 children aged 6 to 14 for over a decade. Measured by cycloplegic autorefraction, emmetropia was defined as refractive error in the horizontal and vertical meridians between +1.00D and -0.25D. In their paper Normal Eye Growth in Emmetropic Schoolchildren,⁹ Zadnik et al demonstrated that the horizontal meridian changed from a mean of 0.64D at age 6 to 0.28D at age 14, and the vertical meridian from a mean of 0.58D at age 6 to 0.33D at age 14. Putting this into clinical terms:

After you have identified the pre-myope, the next challenge is explaining this to parents. The Myopia Profile Managing Myopia Guidelines Infographic, patient brochure and customizable insert (free to download) help to explain risk using a racing car analogy - each of the risk factors above 'fuels' the myopia car towards both onset and progression of myopia.

Perhaps the message on managing pre-myopia is even easier to communicate than for myopia management, when the child already needs vision correction. The key message to parents which will gain traction is probably the short-term view - a chance to delay or prevent their child's need for full time wear of glasses or contact lenses. A myopic parent especially will find this easy to understand.

Managing the pre-myope is arguably more challenging than managing the myope - as the child does not yet require vision correction, this can take optical treatments off the table. There is also minimal research on interventions for pre-myopia, despite the International Myopia Institute stating that preventing myopia is an "even more valuable target"¹ for science and practice than reducing progression after onset.

Prevention is a powerful but difficult target to accomplish. Each earlier year of onset is associated with approximately -0.75 to -1.00D increased myopia later in life.¹⁰ Therefore, focusing attention on the formative stages of myopia and proactively managing pre-myopia could have much greater positive repercussions compared to myopia control. 

Children whom spend less time outdoors, are far more likely to develop myopia.¹⁵ This is especially the case when two hours or less a day of outdoor time is combined with more than 3 hours of near work outside of schooltime.³

The magic amount of outdoor time is a little difficult to pin down, as research studies will variably define outdoor time by the mean reported time (with groups above and below average) or by the intervention (eg the 'recess outside classroom' program by Wu et al, in Taiwan, which amounted to an extra 40 minutes of outdoor time per day). Xiong et al attempted to find a dose-response effect in their 2017 meta-analysis¹⁵ and found that less than 13 hours a week (just under 2 hours a day) was associated with the highest odds ratio for incident myopia. On the basis of five studies investigating a dose response, they found that "an increase of 76 min/day, was needed to obtain a 50% reduction in incident myopia, while an increase of 1 hr/day or 7 hr/week will result in a 45% reduction in incident myopia compared with controls."

This is a simple, effective and achievable intervention which also may have positive effects on other factors of a child’s life such as reduction in body mass index (BMI), and less sedentary behaviours.¹⁶ Don’t forget to encourage sun safety as well.

In contrast with managing myopia, where practitioners have numerous options to prescribe treatment; a lack of evidence exists for proactive management of pre-myopes.

Four studies have shown a potential role for low-concentration atropine in delaying onset in children at risk of myopia development.^17-20 Overall, varying concentrations of atropine from 0.01% to 0.05% reduced the incidence of myopia and resulted in myopic shifts and axial length growth at around half the rate of the untreated children. Although these studies do not indicate the ideal concentration of atropine to use, the outcomes appear to point to stronger concentrations for younger children. Three of these four studies were conducted on Chinese children, so efficacy for other ethnicities is yet to be determined. From what we know about 0.01% atropine for myopia progression (less effective for Asian children^21,22, some efficacy for children in North America²³ and European children²⁴), the same could be true for pre-myopia treatment.

This is an exciting development for parents and practitioners alike, as compliance may be easier to achieve and monitor with atropine compared with outdoor time. Would you prescribe atropine for a pre-myopic child? Ultimately this comes down to collaborative communication with the parents to gain informed consent.

HAL lenses have been commercially available since 2022 and have established solid efficacy in controlling axial elongation and myopic progression in myopic children.¹⁴ In 2024, Zhang et al investigated the use of highly aspherical lenslet (HAL) spectacle lenses to slow axial elongation and myopic refractive shifts in pre-myopic children.²⁵

This was the first study to explore the early intervention and prevention of myopia using an optical treatment. A 1-year randomized controlled trial was performed where 108 Chinese children aged 6 to less than 10 years (mean age 7.0 years) with spherical equivalent refractive error 0.00 to +2.00 D, were randomly assigned either HAL or single vision lens (SVL) spectacles to wear at least 5 days per week and at least 4 hours per day. All lenses were prescribed with 0.00 dioptres. There was a clear relationship between increased wearing time and smaller changes in AL and SERE. Wearing spectacle lenses with HAL for at least 30 hours per week (exceeding the mean wearing time) significantly reduced AL elongation, with 0.11mm growth in one year compared to 0.27mm in SVL wearers. 

As this area of myopia research grows, this may potentially become a very low risk intervention option for some children. Whether other myopia control spectacles lens products are able to demonstrate similar effects is yet to be determined. The biggest concern with prescribing spectacles for a perfectly sighted child is the issue of managing compliance and gaining traction with parents.

RLRL therapy has received growing attention within the myopia management sphere in recent years as numerous clinical trials have reported the effectiveness of this treatment in slowing axial elongation and myopia progression in children.²⁶ Among these, one study emerged which explored the use of RLRL treatment for pre-myopes.

He et al²⁷ in 2023 assessed the efficacy and safety of RLRL therapy in preventing incident myopia among pre-myopic children. A 12-month randomized clinical trial was conducted in China on 278 children aged 6 to 11 years with pre-myopia, defined as spherical equivalent refractive error ranging from +0.50 D to -0.50 D. Half of the cohort received two, 3-minute RLRL therapy (Eyerising) sessions per day, for five days a week, while the other half were controls. They found reduced myopic shifts of 0.17mm in AL and 0.41D for SER after exposure to repeated low-level red light. For those able to continue therapy uninterrupted (n=9), there was a greater reduction in myopia incidence. The RLRL was well-tolerated by the children with no persistent symptoms or structural changes on OCT. 

Despite the convincing efficacy of RLRL therapy in recent studies, further studies need to confirm tolerance and safety over longer periods and with other RLRL devices. In terms of practical constraints, RLRL remains not widely available outside of China and is awaiting regulatory review in markets such as Australia.

It would make logical sense that if a child presents with a binocular vision disorder linked to myopia onset, that managing the disorder may reduce risk. These specific disorders are:

• Higher accommodative convergence (AC/A) ratios, typically seen with esophoria, have an increased risk of myopia development within one year of over 20 times.⁴
• Accommodative lag may also be a risk factor but there is conjecture.⁵
• Intermittent exotropia (IXT) has also been associated with onset of myopia - 50% of children with IXT are myopic by age 10, and 90% by age 20.⁶

It's important to note, though, that intervening in the above disorders for the purposes of delaying or preventing myopia onset is not evidence based - no study has been published to this effect. It is worth treating these disorders regardless, especially considering that binocular vision disorders can cause educational delays, asthenopia and headaches in children.²⁸

There is no evidence that treating children classified as pre-myopic with myopia control contact lenses are effective in preventing the onset of myopia. Contact lenses, by nature, require significant parental intervention, cost and increase the risk of eye infection. However in parents whom perhaps have an older child already in contact lenses, potential strong enthusiasm to utilise an effective treatment is understandable. When faced with clear progressors (children who have rapidly changed from hyperopic to plano) with strong risk factors in the circumstances of a family keen for treatment, weighing the risk and benefits of contact lens treatment up with the patient and parent should be done clearly and carefully. For more information on paediatric contact lens wear, see our blog Contact Lens Safety in Kids.

If the conversation has already occurred with parents on the identification and risks of pre-myopia, and outdoor activity and myopia control options discussed - and a child does progress to myopia, this makes subsequent myopia control intervention an easier decision for both practitioner and family.

By identifying pre-myopes as part of your routine clinical paediatric care, you will better integrate myopia control into your practice. Children can progress quickly, especially if you have already identified them as high risk, so ensuring that they are reviewed in at least six-monthly intervals important.

• Why outdoor time matters in myopia development

• Atropine for pre-myopia

• Spectacles with highly aspherical lenslets for pre-myopia

• Can red light therapy delay myopia onset?