How to identify and manage pre-myopes

First published: October 18, 2020
Last updated: December 9, 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:

1. Family history – one myopic parent increases risk by three-fold, while two myopic parents doubles this risk again²
2. 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
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
4. Current refraction (also known as ‘hyperopic reserve’) – the most significant risk factor of this lot for future myopia is if a child exhibits less than 0.75D of manifest hyperopia at age 6-7. This risk is independent of family history and visual environment, and was determined from the multi-ethnic CLEERE study in the USA.⁷ The hyperopic reserve is likely higher for Asian children (~+1.50D), which may or may not vary with age - read more in our article What is the 'hyperopic reserve' in pre-myopia?

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 and available in 20 language translations) help to explain risk using clear categories and a simple green / yellow / red traffic light risk categorization. Put simply, more yellow and red risk factors will escalate the overall risk of myopia development and progression. 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 make optical treatments more challenging for compliance. There is only a small amount of research on interventions for pre-myopia, but it is growing, which is important as the International Myopia Institute states that preventing myopia is an "even more valuable target"¹ for science and practice than reducing progression after onset. 

Prevention is a powerful but challenging 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 after onset. 

Children who spend less time outdoors are far more likely to develop myopia.¹¹ 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 appears to be at least two hours per day which can be spread across the week - more precisely, 13+ hours per week as found by meta-analysis.¹¹ 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." 

How increased outdoor time confers protection against myopia onset is another mystery. The physiological effects of light exposure, the brightness of outdoor light, the uniformity of the dioptric visual field and spatial frequency of the visual environment have all been suggested as potential mechanisms.^12-14 An interesting randomized controlled trial in China¹⁵ evaluated the effect of modifying the walls of an indoor classroom to resemble an outdoor scene on myopia development, as opposed to implementing increased outdoor time as most other studies. Preliminary results showed efficacy of the outdoor scene classroom in preserving the hyperopic reserve in students aged 8-10 with ⩽+1.00D hyperopia over 1 year (-0.26D vs -0.40 D, 0.15 mm vs 0.22 mm). It was not effective in altering refractive changes in emmetropic or myopic children.¹⁶

Spending more time outdoors 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.¹⁷ Don’t forget to encourage sun safety as well.

Four studies to date on low-concentration atropine suggest that it may be useful for delaying the onset of myopia in children at risk.^18-21 Overall, varying concentrations of atropine from 0.01% to 0.05% have been shown to reduce the incidence of myopia and result in myopic shifts and axial length growth at around half the rate of the untreated children. Although these studies employed varying concentrations of atropine, 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^22,23, some efficacy for children in North America²⁴ and European children²⁵), the same could be true for pre-myopia treatment.

Highly aspherical lenslet (HAL) spectacle lenses have been commercially available since 2022 (Essilor® Stellest®) and have established solid efficacy in controlling axial elongation and myopic progression in myopic children.²⁶ In 2024, Zhang et al investigated the use of HAL spectacle lenses to slow axial elongation and myopic refractive shifts in pre-myopic children.²⁷

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. 

Logically, this directs attention towards whether the other next-generation myopia control spectacle lenses are able to replicate similar effects. 

DIMS lenses (Defocus Incorporated Multiple Segments) are a close competitor to HAL lenses in terms of myopia control efficacy and design principles. Yang et al at the 2024 IMC reported good adaptability of pre-myopic children to full time wear (≥ 10 hours) of DIMS spectacle lenses. Their efficacy data indicated an increase in SER +0.16D and AL +0.10 mm over 6 months, with no control group.³⁰ Results for other spectacle lens types, such as ‘Multiple defocus’³¹ and ‘Multizone-defocus-plano’³² lenses have indicated early efficacy in slowing myopic progression and axial elongation in Chinese pre-myopic children, again with wearing time influencing outcomes. 

As this area of myopia research grows, this may become a very low risk intervention option for some children. The biggest challenge with prescribing spectacles for a child with presumably normal unaided acuity is 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.³³ Among these, one study emerged which explored the use of RLRL treatment for pre-myopes.

He et al³⁴ 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 Myopia Management Device) 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. Read more in our article Can red light therapy delay myopia onset?.

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.³⁵

There is no evidence (yet) that treating children classified as pre-myopic with myopia control contact lenses are effective in preventing the onset of myopia. Contact lenses, by nature, could be more challenging a prospect for pre-myopia management than spectacles or even atropine. In families who already have another sibling wearing 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) and strong risk factors in these circumstances of a family keen for treatment, weighing up the risk and benefits of contact lens treatment with the patient and parent should be done clearly and carefully. For more information on paediatric contact lens wear, see our article 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. Where there is opportunity to intervene beforehand to delay myopia onset, though, this is the ideal outcome. Intervention could mean firstly discussing the visual environment and reviewing more frequently; through to prescribing one or more of the evidence-based treatments detailed above. 

By identifying pre-myopes as part of your routine clinical paediatric care, you will better integrate myopia management 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 is important.