To introduce myself, I’m Amisha and have been an Optometrist for 10 years. During the Covid-19 lockdown I found myself with more time on my hands than usual. It gave me the opportunity to upskill myself and delve deeper into the world of myopia management.
Having been asked by fellow practitioners on what I have been up to, and what myopia management is all about, I thought I would share some of my findings. Hopefully, this article will not only introduce myopia control into your clinic but also encourage more learning into the area.
Background on myopia
By 2050, an estimated 50% of the world’s population are predicted to be myopic and according to the World Health Organisation (WHO) that is a stunning 4.7 billion people¹.
Myopia occurs when light focuses in front of, instead of on the retina, resulting in distance vision being blurred. The underlying mechanism is due to the elongation of the eye with myopic progression occurring due to an increase axial length. Whilst this refractive error can be corrected with single vision spectacles and single vision contact lenses, these types of corrective methods do not address the excessive elongation of the eye.
Myopia typically presents in childhood and progresses in magnitude through to teenage years. The increase in prevalence of myopia means pathological complications pose a problem. Ocular conditions include myopic maculopathy, retinal detachment, cataracts and glaucoma, all of which can cause severe visual impairment.²
An axial length measurement of >26mm means that patient has a 25% risk of visual impairment.³ There is no ‘safe’ level of myopia and every dioptre of myopia increases the risk of eye disease.⁴ Higher myopes with an axial length measurement of >30mm have an alarming 90% risk of being affected by these ocular conditions which is why it is so important to control axial elongation to minimise the risks of myopia³.
Genetics play its part in the onset of myopia. My 15 month old daughter is 6 times more likely to develop myopia thanks to my husband and I both being myopic. However, it is not just genetics that is contributing to this epidemic. Research suggests that now, more than ever, lifestyle has a part to play too and that children are becoming myopic much earlier than before.
We all have first hand experience with how the lockdown regulations aimed at flattening the novel coronavirus infection curve around the world, has literally increased our screen time, including children. Children now spend a huge chunk of their daily routine indoors, staring at screens in closer proximity compared to conventional books. Over the decades, the increase in myopia cases has occurred simultaneously with technological advances in electronic gadget development.
Evidence shows a significant predictor of myopia onset is having a less hyperopic refraction at a young age. The collaborative longitudinal evaluation of ethnicity and refractive error (CLEERE) study was a 20 year study which suggested measuring children’s refractive error as early as age 6 could help predict who would become myopic. The study found that children who grow up to have normal vision are actually somewhat hyperopic in year 2 class (age 6-7 years) at primary school, so those who have little to no hyperopia at an early age are likely to develop myopia as their eyes continue to grow. In terms of refractive error numbers this equates to +0.75D or higher indicating a low risk of myopia at age 6 and anything less than +0.75D posing a risk to developing myopia⁵.
However, the good news is there is compelling evidence showing that the progression of myopia in children can be slowed down. The idea is you start curbing myopia in children at the earliest point to slow down axial elongation.
What methods are available to manage myopia?
We are currently seeing a shift in myopic management from simple correction of visual function to controlling the progression of myopia.
Educating parents, grandparents and guardians from an early stage about known risk factors, how many they fall into and how small lifestyle modifications such as increasing time spent outdoors⁶ and limiting near vision activities⁷, could delay the onset of myopia.
However, once that child is myopic, we then need to look at the options available to correct the refractive error and slow the rate of myopia progression, these take form in optical interventions and pharmaceutical interventions.
- Contact lenses, specifically multifocal soft contact lenses and orthokeratology are an option to manage myopia. CooperVision’s MiSight 1 day soft contact lens is a dual focus contact lens with FDA approval to control myopia in young children. The spherical powers range from -0.25 to -6.00D in 0.25D steps. A three year trial was performed by Chamberlain et al. and results of this randomised, doubled masked clinical trial demonstrated the effectiveness of the MiSight lens⁸. Sankaridurg et al conducted a two year trial looking at contact lenses that impose myopic defocus and contact lenses that have an extended depth of focus (EDOF). Mark’Ennovy’s Mylo lens is an EDOF soft monthly contact lens made with silicone hydrogen material and was designed with the Brien Holden Vision Institute (BHVI) Power ranges from -0.25 to -15.00D in 0.25D steps. NaturalVue is a 1 day soft contact lens from Visioneering Technologies. It is a soft multifocal lens that also has an EDOF design and is available in spherical powers up to -12.25D in 0.25D steps. There are numerous soft multifocal contact lenses available however these are considered as off-label use as they are not specifically designed for myopia control. Orthokeratology uses rigid contact lenses and are worn overnight. These lenses are designed to reshape the cornea by flattening it to create a myopic defocus, which in turn controls axial elongation. Menicon’s Bloom Night lens is a specially designed reverse geometry ortho-k contact lens. The retardation of myopia in orthokeratology (ROMIO) study evaluated this lens to manage myopia. All four contact lenses mentioned above are CE marked and licensed for use in European markets specifically to control myopia.
- Spectacle therapy is available to control myopia with progressive addition lenses (PALs) or bifocals. The correction of myopia evaluation trial (COMET) looked at PALs compared to single vision lenses in myopia management. Cheng et al. conducted a trial looking at bifocals and prism in bifocals. Under correction with both optical appliances is not advised as studies show that does not slow down myopia⁹. There has been development of specific myopia management spectacle lenses from Zeiss, Essilor and Hoya. Zeiss has a lens portfolio specifically designed for children’s eyes including MyoVision. Hoya has the MiyoSmart lens with Defocus Incorporated Multiple Segments (DIMS) technology and a two year clinical trial showed proven results to curb myopia. However, both the Zeiss and Hoya myopia lenses are not available in the UK as yet. With further advancements I am sure we will see new products in this market and more recently SightGlass vision received approval for their lenses to be available in Europe to slow myopic progression in children.
- Pharmacological intervention with low dose atropine has also been shown to slow down myopia. Atropine is a non selective antimuscarinic. Although the exact mechanisms of its actions are still unknown, it is thought that atropine blocks acetylcholine. In turn, acetylcholine affects dopamine levels which has a role in eye growth. Atropine for the treatment of myopia (ATOM) 1 and ATOM 2 studies showed that atropine can be effective to reduce axial elongation but a rebound phenomenon can occur in high doses and that atropine 0.01% was shown to have the best results. The low concentration atropine for myopia progression (LAMP) study also looked dosage but found that 0.05% atropine gave a better efficacy of myopia control. Atropine is not yet available for commercial use in the UK, however with ongoing trials, it is only a matter of time before it can be used here for myopia control
Each optical intervention has its advantages and disadvantages and ultimately each method does its part to slow down axial elongation, some with higher efficacies than others.
Suggestions to Optometrists
As eye care professionals our role is going to change from only correcting myopia to also controlling it. There really is no better time to educate ourselves on this topic to slow down the rate of myopia in children.
Where to get more information and learning:
- BHVI myopia management course
- BCLA have recently launched a myopia management certificate
- Contact lens manufacturers have learning academies available to practitioners and host webinars and peer review discussions about myopia management and contact lenses in children
- College of Optometrists
- International Myopia Institute (IMI) issued clinical management guidelines for myopia control
My approach to myopia management in practice will be a three step process; understand, plan and review:
Understand - get to know everything about your patient through history and symptoms and undergo base line investigations to identify risks
- History- age (younger age of onset contributes to faster myopic progression), gender (myopia tends to occur more in girls), ethnicity (higher incidence in children with east Asian ethnicity) and family history (both parents being myopia gives a 1 in 2 chance of that child becoming myopic, with one myopic parent a 1 in 3 chance for that child and with no myopic parents gives a child a 1 in 4 chance of becoming myopic) ¹⁰ ¹¹
- Refraction- retinoscopy, subjective refraction and cycloplegic refraction
- Binocular vision assessment- high accommodation lag, cover test with an esophoria at near and a high AC/A ratio all point towards myopia ¹⁰ ¹¹
- Lifestyle- there is evidence that less than 90 minutes of time spent outdoors a day and concentrating on near vision tasks at close working distances of 20cm or less and for periods of 45 minutes or more, both contribute to myopia onset ¹⁰ ¹¹
Plan - once a child has been identified as being myopic put a plan in place
- Calculate the predicted myopic progression and potential prescription end point (can use the BHVI calculator or Myappia)
- Discuss the risks and implications of myopia
- Discuss the methods available for myopic control and the potential risks of each type. Support families to make informed decisions regarding treatment
- Correct myopia appropriately ensuring optimal visual acuity
- Measure the axial length of the child as base line data to compare back to, this is considered ‘gold standard’ when monitoring myopic progression. Alternatively if the practice does not have access to an ocular biometer then refraction results can be used to monitor progression.
- Provide written information to the patient and parent/guardian to support them
- Set realistic expectations with the patient and parent/guardian when predicting the efficacy of intervention chosen. It is important they understand myopia management is not about getting rid of the prescription altogether but keeping it as low as possible to prevent future ocular complications
Review - when will you monitor progress?
- Each optical method chosen has different review schedules which are important to adhere to in order to achieve compliance and monitor any progression. These can be found in the IMI guidelines.
- Myopia management uses evidence based practice so it is key to keep up to date with new clinical research and any updates in industry guidelines to continue to be able to give the best patient care and management
Ultimately optometrists have a key role to play and should help lead the way in myopia management. Optometrists are professionally saddled with the responsibility of discussing the available myopia management options with parents, grandparents and guardians of children living with myopia. We can improve children’s long-term visual health and quality of life by modifying our approach from just correcting the myopic prescription to actively managing the level of myopia.
Let us not be short sighted about myopia control and see it as a standard in our ways of working so we can battle against this ocular epidemic together.
I hope this article has given you a brief insight into this topic, thank you for reading.
#children #myopia #myopiamanagement #myopiacontrol #contactlenses #orthokeratology #coopervision #menicon #markennovy #naturalvue #swisslens #zeiss #hoya #sightglass
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