An overview of myopia management interventions

International myopia experts provided an overview of interventions for slowing the progression of myopia during a webinar organised by the Singapore National Eye Centre (8 October, held online).

The Myopia dialogues webinar ‘Evaluating myopia patients and interventions’ covered a range of topics, including assessing how ‘normal’ myopia behaves, determining when there might be a secondary condition underlying myopia and the different options available for myopia management.

Below, OT provides a summary of some of the points raised during the meeting.

How myopia develops

Head of the Myopia Centre at the Singapore National Eye Centre, associate professor, Audrey Chia, provided an overview of how the eye develops.

“There’s a progression from hyperopia to emmetropia. For some people, the eye gets too big – and that becomes myopia,” Chia shared.

“It’s important to remember that refractive error is not just the eyeball size, but the cornea, which does most of the refraction, and the lens power as well,” she highlighted.

She shared how there is a rapid increase in eyeball size between the ages of three and seven.

Over the first 10 years of a child’s life, Chia highlighted that lens thickness decreases, although the curvature of the cornea stays relatively constant.

“Past infancy and early childhood, there seems to be a split. The eyes that are going to remain emmetropic will continue to grow at a low rate, while the eyes that are becoming myopic will rapidly increase,” she said.

Beyond ‘normal’ myopia

Clinicians discussed a series of cases where secondary conditions influenced myopic progression.

Dublin paediatric ophthalmologist, Professor Ian Flitcroft, outlined a case where retinopathy of prematurity – a common cause of myopia – and genetic factors formed a backdrop to myopic growth. Flitcroft described how these factors complicated management decisions.

Professor Padmaja Sankaridurg, of the University of New South Wales, discussed a case involving the progression of myopia in a child with high levels of astigmatism.

Sankaridurg highlighted that astigmatism may influence which myopia management option is selected, as not all interventions are appropriate for astigmatic correction.

She shared that spectacles involve the least amount of chair time and are convenient for young children.

She highlighted that the range of spectacle lenses is extensive, both in terms of sphere as well as cylinder.

“Another advantage, when we think about spectacles, is that you can combine myopia management spectacle lenses with atropine,” Sankaridurg said.

Sankaridurg shared that ortho-k can be effective in managing myopia in patients with low levels of astigmatism.

Past infancy and early childhood, there seems to be a split. The eyes that are going to remain emmetropic will continue to grow at a low rate, while the eyes that are becoming myopic will rapidly increase

However, she highlighted that there may be fitting issues using ortho-k for patients with a higher magnitude of astigmatism. Toric ortho-k lenses could be considered in this instance, Sankaridurg added.

Turning to soft contact lens options, Sankaridurg reflected that with moderate to high levels of astigmatism, there is potential for vision quality to be affected.

She added that, in time, toric multifocal soft contact lenses may become available.

Chia discussed the case of a young child with high myopia who was later found to have cone-rod dystrophy.

Reflecting on points raised during the discussion, webinar moderator, Dr Loh Kai-Lyn, highlighted that sometimes a cautious approach is warranted when children present with high levels of astigmatism or myopia at a young age.

“We sometimes need to be aware that myopia is not just myopia,” she said.

Spectacle lenses

Sankaridurg provided an overview of different spectacle lenses for myopia management.

She highlighted that the hypothesis behind both progressive addition lenses and bifocal lenses was that they would reduce accommodative lag and therefore slow the progression of myopia.

“At the present time, we do have some progressive addition lenses that are available from labs across the world, and we also see them being used in conjunction with high concentrations of atropine,” she said.

Turning to peripheral defocus spectacle lenses, Sankaridurg highlighted that these lenses have a continuous power profile that aims to induce peripheral hyperopic defocus.

Sankaridurg also explained the reasoning behind simultaneous defocus lenses.

“The technology is using multiple segments or lenslets to create simultaneous myopic defocus at the retina. The hypothesis is that having myopic defocus would slow the progression of myopia,” she shared.

She added that this category of spectacle lenses is seeing the same level of efficacy as ortho-k and contact lenses.

Sankaridurg shared that an emerging category of spectacle lenses incorporates diffusive dots.

“By reducing contrast, you can slow the progression of myopia,” she said.

Turning to the advantages of spectacle lenses for myopia management, Sankaridurg highlighted its convenience.

“Even though we can fit young children with contact lenses, it's quite a difficult conversation to have with parents,” she said.

However, a drawback of spectacle lenses is that they are not yet available at all degrees of astigmatism.

Turning to the relative cost of this management option, Sankaridurg shared that the lifetime cost of spectacle lenses was found to be the most cost-effective myopia management option in Australia.

In China, spectacle lenses were the second most cost-effective option (with atropine as the most cost-effective option). 

Contact lenses

Ophthalmologist Dr Zhi Chen, from Fudan Unviersity Eye & ENT Hospital in Shanghai, provided an overview of multifocal soft contact lenses and ortho-k contact lenses for myopia management.

Chen highlighted that in China, there are more than three million ortho-k prescriptions for myopia management each year.

However, the popularity for this management option has subsided slightly as the uptake of myopia management spectacle lenses has increased.

Chen emphasised that the communication around ortho-k is straightforward.

“I would like to emphasise that not all ortho-k designs are good for myopia control,” he said.

Chen highlighted that multifocal soft contact lenses have only been adopted within China over the past couple of years for myopia management.

He shared that in moderate or high myopes, ortho-k lenses work well. However, he added that in low myopes, multifocal soft contact lenses tend to work better than ortho-k lenses.

Chen shared that he prioritises the efficacy and safety of a treatment when considering which management option is appropriate, followed by affordability.

Atropine

Chia highlighted that atropine has been in use for a long time, with the medication used at the turn of the 20^th century for treating accommodative spasm.

She shared that atropine has a dose-related response, with higher doses resulting in a more significant effect.

However, Chia added that the side effects and rebound effect is also greater when the dose is higher.

She shared that low dose atropine is now a common treatment in many countries, while work in underway in many additional jurisdictions to licence the treatment.