A Gathering of Old Pals Global Orthokeratology and Myopia Control Conference

Singapore is often referred to as the myopia capital of the world. When you consider the lifestyles led by Singaporeans, it’s easy to understand why more than 80% of the country’s youth is living with the disease.

It was fitting then, that Singapore was the host nation for this year’s Global Orthokeratology and Myopia Control Conference, which attracted more than 500 optometrists from Singapore, Malaysia, Hong Kong, China, Philippines, Vietnam, Indonesia and Australia.

This lively event was organised by Dr Charlie Ho, President of the Asia Optometric Congress (AOC); Dr Oliver Woo, Lead of the AOC Academy of Orthokeratology and Myopia Control; Dr Alex Ong, Chair of the Organising Committee; and Ken Tong, President of the Singapore Optometric Association.

The speaker line-up was impressive and included six global leaders in optometry: Scientia Professor Fiona Stapleton (Australia), Mr Tan Thok Chuan (Malaysia), Dr Woo (Australia), Professor Langis Michaud (Canada), Dr Alex Ong (Singapore), and Professor Wei Zhong Lan (China).

DELVING INTO THE DEEP END WITH BOOTCAMPS

Bootcamps kicked off the conference, with delegates invited to attend full-day intensive sessions aimed at establishing and building on existing knowledge of prescribing orthokeratology (OK) contact lenses to temporarily correct for refractive error and control myopia. Having listened to the experts from various suppliers, there’s no doubt that this is an area in which practitioners will always find something new to learn.

The importance of topographical corneal mapping at initial presentation and over time could not be emphasised enough, despite the challenges of mapping children – for which practical tips were provided.

Speaking at Menicon’s bootcamp, Dr Ong said, “Try to take very good corneal maps, otherwise you will mess up detail (when ordering lenses)… you only get one chance to take a proper baseline map so get as many (images) as you can – ask the patient to keep blinking then the map will look beautiful.”

Noting that an irregular tear film will affect the topography map and, therefore, your judgement, he recommended using low viscosity eye drops before topography (thicker eye drops will take longer to even out on the cornea, which is necessary before mapping). Dr Ong said the best time to take scans of children’s eyes is in the morning, before their tear film changes and before the OK effect begins to wear off.

At the Johnson and Johnson Vision bootcamp, Dr Woo recommended optometrists always take a patient’s baseline maps themselves – and take their time about it. After that, it’s appropriate for the task to be delegated to a technician. He noted the importance of calibrating the topographer every two weeks for consistent scanning and said to set the scales to refine map presentation. In most cases, the device’s pre-set scales will be adequate, however the custom option provides smaller refinements, allowing better visualisation of small effects like central islands.

At the EssilorLuxottica bootcamp, Mr Tan highlighted the enormous capacity OK lenses have to serve the patient by reshaping the cornea. However, ECPs must understand the “fundamental anatomy of the OK lenses they are prescribing” to optimise this potential. For example, to change the way a lens is sitting on the eye you can change the sagittal height by flattening, steepening or even raising the reverse curve or the alignment curves of the lens.

Dr Woo said ECPs can use an empirical topography-based fitting process or a diagnostic trial lens fitting process, depending on their preferences and available equipment.

An empirical topography-based fitting process uses software to calculate and order the customised lens. Once the lens arrives, patients are fitted and the lens efficacy is evaluated over time.

With a diagnostic process, the patient is immediately fitted with a trial lens, the efficacy for which is evaluated before the customised lens is ordered.

The former is “easier and quicker”, with the topographer’s software guiding the practitioner. Other than the topographer, which can be used for multiple other clinical tasks, initial investment is low as there are no trial sets.

However, some practitioners prefer the more traditional diagnostic approach as the patient immediately experiences a trial lens on their eye. The cost of the trial lens is amortised with the first fitting.

Regardless, Dr Woo said he gets patients back regularly within the first two months to assess the fit and check their lens handling and hygiene practices. After two months, he asks them back every three to four months. “Try to think about it from the parent’s perspective – how often would you like your child to be seen and cared for? Six months (between visits) for me is a little too long – many things can happen during this time.”

CELEBRATING COURAGE

The first official day of the GOMCC commenced with a Lion Dance performance by the Singapore Polytechnic Lion Dancing team. The lion dance is a symbol of Singaporean heritage; Singa meaning ‘lion’; a symbol of strength, courage, and prosperity.

Following on from the practical bootcamps of the previous day, the lectures explored more theory behind the evolution of the myopic eye, the role of the environment vs genetics in myopia progression, strategies to maintain ocular health for contact lens wearers (with a focus on myopia management lenses), and alternative treatments to slow progression.

Prof Michaud spoke about the three stages of the eye’s development from hyperopia at birth through to emmetropisation and finally, homeostasis in adulthood. He said the eye adapts not only to its growth but also to the natural environment, with genetics explaining only 30% of the outcome. The rest comes from the individual’s environment. Computers aren’t the enemy of myopia – but reading distance is, because a close reading distance stresses the visual system. Ambient illuminance, chromacity, and spatial frequency also impact myopia.

Controlling myopia is “a long journey” that should be started early and anticipated to last until the patient is around 24 years of age. He referred to an International Myopia Institute white paper, which shows the eyes of 40% of university students are still evolving, albeit at a slower rate than children.

Prof Michaud stressed the need for an individual approach to myopia management, with treatments that drive a response from the retina.

He said defocus is one thing but its more the spherical aberrations and the coma that drive retinal response. The higher the myopia, the higher the spherical aberration is; the higher the plus you can bring into this system, the better.

Because it takes time for the retina to react appropriately to these signals, the highest impact of spherical aberration comes at three months.

It’s important to select the right patient for OK and continually review their progress. OK may have a positive impact for two years before the effect begins to slow, signalling the need for a new lens design or the addition of “something else to the treatment”.

He reminded delegates that OK is more effective in younger patients than those over eight years of age. Finally, Prof Michaud reiterated a key message communicated during the bootcamps, which is the need to monitor progression with topography.

“You don’t know until you look at the topography what this lens will do to the cornea. If you don’t look at topography you don’t know what you’re doing,” he said.

TREATMENT TARGETS

Building on Prof Michaud’s discussion of the eye’s development, Dr Arne Ohlendorf from ZEISS spoke about the importance of making data-driven decisions to give children the best care for their eyes.

We know that as children grow, their eyes grow with them, which he said, can best be seen in the continuous increase in axial length until the eye is fully developed.

Dr Ohlendorf said, “There seems to be physiological growth behind the development of the eye – the eye tries to get the best image on to the retina by changing the axial length, the thickness of the crystalline lens, and the shape of the cornea.”

Longitudinal research in China and Germany has allowed the establishment of a curve demonstrating age-normal physiological growth. This curve shows us there is little difference between the eye lengths of very young children growing up in China compared with Germany, he said. However, it also shows a trend towards myopia with increased age for all ethnicities. When comparing progression by ethnicity, we see a difference of 1.5–2D between some children in China vs Germany. The curve for the Chinese children is similar to those of Malaysian and Singaporean children (although children in Singapore progress more in the median compared to China, especially from seven to eight years of age).

Progression of myopia depends on multiple factors – one being seasonal change with the rate of progression being higher in winter compared with summer, when children spend more time inside.

Dr Ohlendorf concluded by stating that the objective of myopia management is “to slow down myopia progression, therefore the target is age-normal physiological growth, as indicated by the physiological emmetropic curve, which acts as the baseline value used as the reference to evaluate treatment effectiveness of a myopic progression intervention”.

AIER EYE HOSPITAL FINDINGS

The myopia rate of children and teenagers in China ranks among the highest in the world. The Aier Eye Hospital Group, which has more than 800 facilities across the world, the majority of which are in China, is working to combat this myopia epidemic, and amassing extensive data in the process.

As well as establishing a comprehensive myopic prevention system, the Aier Group is very much involved in working to slow myopia progression. In a keynote, Professor Lan Wei Zhong reported that the group, staffed by 8,000 eye doctors, had dispensed 1,000,000 pairs of orthokeratology lenses for 230,000 children over the past 20 years. They’ve found that the older the age of the child, and the longer the axial length at the start of the treatment with OK, the lower the progress over five years in terms of lessening axial length growth. “So use OK lenses as early as possible: you can expect more cumulative benefits than from single vision lenses,” Prof Lan said.

With such a massive number of children being treated for myopia, there is no doubt that this is where strong evidence for efficacy of approaches to disease management will come from in the near future.

THEORISING ON ENVIRONMENT

We’ve long heard discussion about the impact of the environment on myopia onset and progression and at GOMCC, Professor Saw Seang Mei (from the Singapore Eye Research Institute and National University of Singapore) asserted the need to get children spending more time outdoors.

Prof Mei said the two major environmental risk factors for myopia onset and progression are: too much near work or too little time outdoors – as demonstrated in both observational and clinical studies. A study comparing children in Sydney and China found that despite children in Sydney reading for more hours each week, they had significantly less myopia progression, theorised to be because of extensive time spent outdoors (14 hours vs three hours per week).

One theory for this outdoor effect is that luxe levels, which are much higher outside than indoors, trigger the release of retinal dopamine, which prevents the elongation of the globe. The luxe level of light doesn’t need to be high – even if a child is protecting their eyes by wearing sunglasses and/or a hat while outdoors, they will benefit from increased luxe levels compared with being inside.

CONTACT LENS COMPLICATIONS

Prof Stapleton was invited to the conference to speak about complications with contact lens wear and management of dry eye for young contact lens wearers.

She reviewed how contact lens complications, such as contact lens-related microbial keratitis (MK), Acanthamoeba keratitis (AK) and corneal infiltrates occur, the risk factors, presenting features, and how they can best be managed.

“It’s helpful to consider complications on the basis of their presumed aetiology.”

She said that of contact lens-related microbial keratitis (MK), 35–65% of new cases presenting to an urban hospital are due to contact lens wear, however, the overall incidence is very low, and there is a low risk of severe diseases in daily disposable wear.

Acanthamoeba keratitis (AK) is a rare disease but has a predilection for contact lens wearers who make up about 95% of the disease load.1 It is generally considered a disease of daily wear, but most studies have estimated a similar risk for wearers of rigid gas permeable lenses and daily wear soft lenses. Work in the United Kingdom by Professor Nicole Carnt found a lower risk in daily disposable soft contact lenses.2 Australian research found that AK is three times more common in tropical compared to temperate climates. Additionally, an infectious keratitis study with the Asian Corneal Society found 9% of AK cases were attributed to coloured contact lens wearers and only 1% to refractive lens wearers.3

The risks of corneal infiltrates with OK wear are “super low and not appreciably different between adults and children”, at around 0.17% in adults and 0.42% in children, she noted.

To reduce the risks of contact lens complications we need to consider known risk factors: limit overnight wear and pay attention to hygiene in daily wear, and always avoid the use tap water for any aspect of contact lens care.

“We used to think that water avoidance was only important for AK disease, but we have emerging evidence to suggest this is important to avoid any type of infection and corneal infiltrates,” said Prof Stapleton.

Risks of disease severity can also be reduced with daily disposable contact lenses.

MANAGING DRY EYE

In her keynote address, Prof Stapleton highlighted the importance of understanding how dry eye disease affects children, given reports that myopia is often treated with multifocal contact lenses or OK lenses. While there is limited published evidence on paediatric dry eye disease, it is surprising to find one in five children/adolescents report severe or frequent ocular symptoms, even in the absence of contact lens wear, with prevalence higher among females vs males and older vs younger children.

The signs reported by paediatric dry eye sufferers are less common than those signs seen in adults. With this in mind, it’s not surprising to find that diagnosis and management is less common than in adults. Evaporative disease predominates, accompanied by tear film instability.

Lifestyle factors may be responsible for paediatric dry eye and Prof Stapleton noted that the use of smartphones before bed may increase signs. Contact lens wear is also a risk factor as is air pollution, the pandemic and underlying comorbidities such as allergies, type 1 diabetes, Sjogren’s syndrome, Graft vs Host Disease, Stevens-Johnson syndrome, and juvenile rheumatoid arthritis. Congenital diseases and genetic disorders can also be associated with DED. Vitamin A deficiency, occurring in malnourished children, is a well-known risk factor.

Questionnaires used to assess dry eye severity in adults have been shown to be equally quick and effective with children, and are appealing to them when available via an app. The Tear Film and Ocular Society Dry Eye Workshop (TFOS DEWS) has recommended the DEQ-5 questionnaire for this population.

There isn’t strong evidence for treating children with DED, so they are often treated in a similar fashion to adults. TFOS DEWS II recommends a staged approach, beginning with basic treatments and a conversation about lifestyle, environment, and diet, then moving through various steps as needed, to restore and manage homeostasis, noting that dry eye disease is not completely curable.

Prior to prescribing contact lenses, eye care professionals must optimise the ocular surface, manage lid disease if it is present and remind patients about blinking. There is little awareness of the role of blinking in maintaining ocular health – partial and infrequent blinking is very common. Therefore, parents and patients should also be counselled on the need to blink regularly and completely following the 20:20:20 rule (20 minutes near work, before looking away for 20 feet (six metres) and blinking completely 20 times).

Once a person is wearing contact lenses, if their dry eye severity worsens in spite of treatment, they should be advised to cease contact lens wear. Time for improvement of the ocular surface should be given before reassessing the strategy.

Prof Stapleton concluded, “Counsel the family about the impact of contact lens wear in dry eye – take the family on the journey, using images is very powerful”.

Additionally, she said, “Have a conversation about other risk factors: diet, environment and screen time.”

The GOMCC will return in 2025, this time in Hanoi, Vietnam.

References

1. Ibrahim, Y.W., Boase, D.L.,Cree, I.A., How could contact lens wearers be at risk of acanthamoeba infection? A review. J Optom, Vol. 2, No. 2, April-June 2009. DOI:10.3921/joptom.2009.60.
2. Carnt, N., Minassian, D.C., Dart, J.K.G., Acanthamoeba keratitis risk factors for daily wear contact lens users a case-control study. Ophthalmology. 8 August, 2022. DOI: 10.1016/j.ophtha.2022.08.002,
3. Stapleton, F., Lim, C.H.L., Mehta, J.S., et al. Cosmetic contact lens-related corneal infections in Asia. American Journal of Ophthalmology Volume 229, September 2021, pages 176–183.