How should we manage high myopia?

Are there special considerations for managing and treating high myopia?

It is estimated that there are almost 1.5 billion people with myopia, 163 million with high myopia and a significant proportion of the population suffering non-refractive visual consequences of the worldwide boom in myopia.¹ Estimates suggest that 10 million people worldwide currently have vision impairment from myopic macular degeneration and 3.3 million suffer blindness.² If these numbers don’t feel staggering enough, with projections based on the rising levels of myopia, this number could rise to 55 million people vision impaired and 18.5 million blind by 2050, or 0.57% and 0.19% of the world’s population respectively.²

Young children (under age 10) with high levels of myopia often have an associated general or ocular health condition of concern, and typically require co-management between optometry and ophthalmology. Read more about this in High Myopia in Childhood - Special Considerations and Safe Management. Complications of myopia are rapidly becoming a leading cause of vision impairment in children¹, and myopic maculopathy is already the leading cause of monocular blindness in Japanese adults.³ As Ian Flitcroft first revealed - there is no safe level of myopia, but the risks really escalate in high myopia.⁴ The following describes the steps we should consider in managing our highly myopic patients.

The risk of complications of macular maculopathy escalate exponentially with myopic dioptres: double the risk in the 1-3D group compared to the emmetrope, 10x greater risk in those with myopia of 3-5D and 40x greater risk as myopia increases beyond 5D.⁴

Childhood retinal detachments make up 3-13% of all retinal detachments, so these consequences of myopia are not simply an 'adult only' problem.⁶ Younger children can have limited capacity as observers of their own symptoms, and the consequences of this are significant: 97% of paediatric retinal detachments are macula off.⁷

Once axial length becomes longer than 26mm, the risk of a host of myopia-associated complications increases steeply.⁸ We have discussed how measuring axial length is useful in monitoring myopia progression in Six questions on axial length measurement in myopia management, however it is also useful in assessing the risk of maculopathy and other complications of myopia for the individual patient.

Any myope with an axial length exceeding 26mm could be considered a 'high myope' from the retinal perspective. The IMI Clinical Management Guidelines suggest that these patients be reviewed annually with retinal health examination through dilated pupils.⁹ 

If you don't have access to axial length measurement, even once as a single measure to gain an idea of your patient's disease risk, it's helpful to know that 26mm is approximately equivalent to 5D of myopia.⁸

It's also important to note, though, that variation in axial length can mean that a lower myope can have a longer axial length. Beware these patients in cases where the patient has a flatter cornea - since the cornea doesn't typically tend to change much in school-aged children,¹⁰ a flatter cornea with moderate myopia can be a particular clue to longer axial length. Read more about this in the clinical case A mismatch between myopia and axial length.

If you are an optometrist without access to mydriatic diagnostic drugs, depending on your scope of practice and appropriate clinical pathways in your country, you may need to co-manage with ophthalmology for annual retina

Patients with high myopia, and their families, should be advised of the importance of regular retinal health examinations, and the symptoms of retinal detachment. Blunt trauma is responsible for 90% of giant retinal tears in children,¹¹ so advise parents and patients on this risk and how to avoid it. Protective eye wear (especially if otherwise wearing contact lenses) can be very important for ball sports.

If the retina is at particular risk, for example through predisposing retinal degenerations or prior surgery, the patient may need to be advised to avoid or limit any sports and activities that involve excessive shaking or forces on the head: such as contact sports, extreme roller-coaster rides, trampoline jumping and bungee jumping.

For high myopia, it's important to control the vertex distance in both refraction and optical dispensing. High myopes approaching 10D and beyond can suffer reduced visual acuity¹² and contrast sensitivity¹³ compared to lower myopes, and impaired quality of life similar to that of patients with keratoconus.¹² Ensure you measure vertex distance in refraction, check acuity in a trial frame and attempt to match this in the vertex distance of the frame for best acuity.

Spectacle frame choices for stability and sturdiness; and high index lenses for improved visual quality and comfort, are vital to give high myopes the clearest possible vision. 

Contact lenses can improve distance acuity and field of view in high myopia, and hence are a crucial correction option. Contact lenses, though, require increased accommodative and vergence effort at near compared to strongly powered myopic spectacles. This may not be an issue for children, teens and young adults with normal binocular vision function, but can lead to earlier presbyopic correction required by contact lens-wearing high myopes compared to those wearing spectacles.14

Contact lenses can also have significant functional and psychological benefits for children and teens - read more on these topics in Kids And Contact Lenses – Benefits, Safety And Getting To ‘Yes’.

Since each dioptre increases the risk of myopic pathology and visual impairment,15 it makes sense to discuss myopia control with all myopes at risk of progression.

Most myopia control studies, though, exclude children with more than 5D of myopia which does mean we have to extrapolate the evidence base for these patients. There is a small amount of evidence for high myopia control intervention with orthokeratology and low-concentration atropine.

The only optical intervention with evidence for high myopes is partial correction orthokeratology, which showed a myopia control effect equivalent to at any other level of myopia. In the study, myopes between 6 and 8D were partially corrected to around 4D with the residual refractive error corrected with glasses during the day time.16 The Low-concentration Atropine for Myopia Progression (LAMP) study enrolled children up to around 8D of myopia, with around 10-15% being high myopes. It showed a concentration-dependent myopia control impact of 0.05% and 0.025% atropine, with minimal effect of 0.01%.¹⁷ It did not report specific outcomes relating to baseline refraction.

Other myopia control methods, where available for high myopia correction, can still be discussed with parents and patients, with the caveat that results can't necessarily be predicted for that individual's situation.

There isn't actually a lot of data on this. The main relationship between faster myopia progression is the child's current age - younger children progress more quickly, regardless of their level of myopia at the time.¹⁸

A recent large-scale European study showed faster progression in children aged 7-9 years with more than 4D of myopia. The authors also noted  that regardless of baseline myopia, the 7-9 year olds progressed most quickly. Children younger or older than this, or with lower baseline myopia, didn't progress as quickly.¹⁹

Another recent large study, this time in India, similarly showed fastest progression in children aged 6-10 years. High myopes (6 to 9D) showed faster progression than low and moderate myopes (0.50 to 3D and 3 to 6D respectively), who were similar. Severe myopes (over 9D) showed the fastest progression over one year, even in their later teens and early adulthood.

• In myopes under 15 years, the mean annual progression in low and moderate myopes was just under 0.50D. High myopes were around 0.62D and severe myopes 0.75D.
• In myopes over 15 years of age, low, moderate and high myopes all progressed similarly, by less than 0.25D. The severe myopes over 15 years, though, progressed by around 0.50D in one year.²⁰

The sum total is that children under age 10 will progress most quickly, and high myopes probably will progress a little faster. Severe myopes (9D or more) progress more quickly than the rest, even in late childhood and adulthood. 

1. Manage ocular health in high myopes, by ensuring retinal examination through dilated pupils occur yearly. For optometrists, this may require co-management with ophthalmology, especially in younger children.
2. The best optical correction for high myopes is likely to be contact lenses, which can provide improved acuity, field of view and quality of life. Spectacles are a necessity for all contact lens wearers, though (even if as a backup) so remember to manage vertex distance, dispense a sturdy frame and high index lenses for best vision and comfort outcomes.
3. Every dioptre is important - discuss the options of myopia control for children, teens and young adults with progressive myopia, but be cautious in considering how the results of clinical studies may not directly apply to that particular patient.

• High myopia in childhood - special considerations and safe management

• Clinical case: How to manage the highly myopic toddler

• Clinical case: Retinal detachment in children

• Clinical case: Managing a teenager with very high myopia

• Clinical case: A mismatch between myopia and axial length