Your Crash Course in Managing Myopia

There are plenty of good clinical reasons to practise myopia control. The prevalence of myopia continues to increase globally, especially in South East Asia where 80–90% of 17–18 year olds are now myopic¹ and prevalence of high myopia is as high as 21.6%.²

Disturbingly, with these statistics in mind, there is no known safe level of myopia – even those in the -1 to -3D range have an increased risk of ocular pathology,³ with low to moderate myopia increasing the risk of glaucoma and cataracts being comparable to the increased risk of stroke from smoking >20 cigarettes per day.³ Furthermore, myopia is the dominant risk factor for retinal detachment and myopic maculopathy.³ At -5.00D, the increased risk of myopic macular degeneration and retinal detachment increases by 41 times and nine times respectively.³

most parents do not understand that myopia is a health risk, with many viewing it as an optical or cosmetic inconvenience or an expense

Despite these significant potential consequences, most parents do not understand that myopia is a health risk, with many viewing it as an optical or cosmetic inconvenience or an expense.⁴ 

SAFE, EFFECTIVE INTERVENTIONS

The most important people to target with myopia control are younger patients and those of an East Asian ethnicity who will tend to progress faster and are at increased risk of becoming highly myopic.⁵ Those who are already progressing rapidly (1.00D or more a year), or who have myopic parents, are also at higher risk of rapid progression.

The changes you can initiate right now to improve the outcomes for young myopes are:

Time Outside 

We should all encourage our young, at risk and myopic patients to spend two hours or more outside per day. There is stronger evidence for the link between limited time outdoors and myopia onset rather than myopic progression. However, a recent randomised trial in Taiwan found a 30% reduction in myopic progression when a program was implemented to encourage more time outside at recess and at home.⁶ The study also found that the intensity of sunlight was important, with shorter periods outside in high intensity sunlight, or longer periods under moderate intensity sunlight, both potentially protective against myopia. You can read more about the effect of sunlight in Professor Ian Morgan’s article on page 26.

We should all encourage our young at risk and myopic patients to spend two hours or more outside per day. There is stronger evidence for the link between limited time outdoors and myopia onset rather than myopic progression

Spectacle Options 

It is relatively easy to alter our spectacle prescribing habits. Although this is the least effective option in reducing myopic progression, prescribing executive bifocals is better (or no worse) than traditional single vision spectacles. It can also be used as an adjunct to atropine therapy. Studies suggest that bifocals provide additional reduction of 15% over and above that achievable with PALs.⁷

A recent randomised control trial found more significant reductions of around 50% with a high set prismatic executive bifocal (1.50 add and three base in (BI) prism at near) which was more effective in patients with low lag of accommodation.⁸ Other studies looking at the effect of +2.00 add PALs showed a statistically significant reduction.^14,15 There have been various peripheral defocus lenses tested and this is an area to be carefully watched.

You can read more about the use of spectacles for myopia control in Dr Kate Gifford’s article on page 67 of this issue.

Soft Multifocal Contact Lenses 

A more effective and widely available myopia control option is soft multifocal contact lenses. Although not quite as effective as atropine therapy or orthokeratology (OK), progression can be slowed by about 35–40% with this strategy.⁷

Centre-distance contact lens designs for myopia control have been extensively studied and based on findings, I would recommend patients wear monthly Bausch + Lomb Biofinity Multifocal (+2.00 add D) or CooperVision MiSight daily lenses, on a full time basis.

OK is preferred by many young patients who enjoy being able to spend their waking hours without any corrective lens wear

Fitting is similar to any soft contact lens, however you will need to be accredited to fit the MiSight lens. The advantage of the MiSight, which is now available at our OPSM stores, is that although it is a daily modality, it is based on the older Proclear material. I tend to use soft multifocal lenses in those who prefer contact lenses but are unsuitable or out of range for OK.

Atropine Therapy 

For those who are therapeutically endorsed, low dose atropine therapy is an attractive option with strong evidence to show that it significantly reduces myopic progression.⁷ Atropine is relatively straightforward and low cost for practitioner and patient, and there are no age restrictions for its use, although patients who are younger or more myopic at baseline are more likely to be poor responders.⁹ 0.01% atropine nocte is recommended; higher concentrations generally result in lower progression but increased side effects and myopic rebound after cessation of treatment.⁷ For non-responders to atropine, a stepwise increase in concentration or switching to a different treatment such as OK has been suggested, however the optimal strategy and treatment duration remains unclear.¹¹ Short-term side effects are uncommon with 0.01% atropine, with only 4–7% of patients noticing near blur or photophobia.⁹ Allergies and systemic side effects are also rare with 0.01% atropine and there are no known long-term side effects.¹⁰

Atropine prescriptions must be made up at a specialised compounding pharmacy. The cost varies but our patients currently pay AU$25 per one-month bottle, with more expensive individual minims also available. I typically review patients on atropine six monthly, after initially checking for any side effects of treatment.

It is very important to set realistic expectations at the beginning of treatment. I advise about 50% average reduction in progression,⁷ but that means that some may respond much better while 15–20% may not respond to treatment at all.⁷ It is important to note that the efficacy of treatment may wane over time. More recent studies have suggested that axial elongation remained significant in those treated with 0.01% atropine.¹³ For more information on the use of atropine to control myopia progression, read the article by Dr Loren Rose on page 39 of this issue.

Orthokeratology 

OK is preferred by many young patients who enjoy being able to spend their waking hours without any corrective lens wear. Parents also like that the lenses are only worn at night which means they can supervise their child if needed.

As per atropine, I advise patients that treatment with OK achieves, on average, about 50% reduction in progression.⁷ That said, in my clinical experience, I have achieved better myopia control with OK than low dose atropine, but doing so does require a patient to be willing to adapt to a rigid lens and a greater time and financial commitment. From the clinical perspective, it requires a corneal topographer.

Regardless… you can take action to improve the prognosis for your progressive myopia patients

Prescriptions between -1.50 to -6.00 may be suitable for OK treatment, but higher prescriptions are more difficult, especially for flatter corneas. Lower levels of corneal cyl (<1.50 ‘with the rule’ and <1.00 ‘against the rule’ or oblique) are also preferred but dual axis lenses can help correct larger degrees of corneal toricity.

OK lenses are fitted either empirically (designed by the lab based on a patient’s parameters) or using trial lens fitting. I use trial lens fitting as this gives me more control over the fit and the lenses are often available straight away, both for patients to experience and in the event that a patient needs a replacement.

Although the risks associated with OK are rare and similar to other overnight contact lens wear, ocular issues can be serious and for this reason, I recommend providing patients with information about OK management and associated risks, and obtaining their consent to treat.

For more information about OK, read the article by Dr Paul Gifford on page 60 and by Mark Koszek on page 81.

Combining Atropine and OK 

A recent study by Kinoshita12 found a small additive effect (a 0.09mm increase in axial length vs 0.19mm increase over one year) can be achieved using both atropine and OK over just using OK. However, much more research needs to be done.

WHAT NEXT?

Regardless of your scope of practice, you can take action to improve the prognosis for your progressive myopia patients. If you need to build your skills, there are endless resources and courses that you can take – turn to page 52 to find about some of them.

If you need quick advice, turn to a colleague who practices myopia or consult Dr Kate Gifford’s Facebook group at myopia profile.com. If you feel a patient is best suited to a service you don’t provide, such as atropine or OK, simply refer them on to a colleague who does.

Daniel Wong is an optometrist with OPSM who practices in Castle Hill NSW. He practises myopia control (including atropine therapy and orthokeratology) and sits on several advisory panels, within Luxottica, that focus on contact lenses and myopia control. 

References 

1. Morgan IG, Onho-Matsui K, Saw SM. Myopia. Lancet. 2012 May;379:1739-1748. 
2. Chen M, Wu A, Zhang L, Wang W, Chen X, Yu X, and Wang K. The increasing prevalence of myopia and high myopia among high school students in Fenghua city, eastern China: a 15-year population-based survey. BMC Ophthalmol. 2018; 18: 159. 
3. Flitcroft DI. The complex interactions of retinal, optical and environmental factors in myopia aetiology. Prog. Ret. Eye Res. 2012;31:622-660 
4. McCrann S, Flitcroft I, Lalor K, et al. Parental attitudes to myopia: a key agent of change for myopia control? Ophthalmic Physiol Opt 2018; 38:298–308 
5. Morgan IG, French AN, Ashby RS, et al. The epidemics of myopia: Aetiology and prevention. Prog Retin Eye Res. 2018 Jan;62:134-149. 
6. Wu PC, Chen CT, Lin KK, et al. Myopia Prevention and Outdoor Light Intensity in a School-Based Cluster Randomized Trial. Ophthalmology. 2018 Aug;125(8):1239-1250. 
7. Wildsoet CF, Chia A, Cho P, et al. IMI – International Myopia Institute: Interventions for Controlling Myopia Onset and Progression Report. Invest Ophthalmol Vis Sci. 2019 Feb 28;60(3):M106-M131 
8. Cheng D, Woo GC, Drobe B, Schmid KL. Effect of bifocal and prismatic bifocal spectacles on myopia progression in children: three-year results of a randomized clinical trial. JAMA Ophthalmol. 2014;132:258–264. 
9. Loh KL, Lu Q, Tan D, Chia A. Risk factors for progressive myopia in the atropine therapy for myopia study. Am J Ophthalmol. 2015;159:945–949. 
10. Chia A, Lu QS, Tan D. Five-year clinical trial on atropine for the treatment of myopia 2: myopia control with atropine 0.01% eyedrops. Ophthalmology. 2016;123:391– 399. 
11. Wu PC, Chuang MN, Choi J, et al. Update in myopia and treatment strategy of atropine use in myopia control. Eye. 2019 Jan;33(1):3-13. 
12. Kinoshita N, Konno Y, Hamada N, el al. Additive effects of orthokeratology and atropine 0.01% ophthalmic solution in slowing axial elongation in children with myopia: first year results. Jpn J Ophthalmol. 2018 Sep;62:544-553. 
13. Yam J, Jiang Y, Tang S, et al. Low concentration atropine for myopia progression (LAMP) study. American Academy of Ophthalmology. 2019;126:113-124. 
14. Hyman L, Gwiazda J, Hussein M et al. A randomized clinical trial of progressive addition lenses versus single vision lenses on the progression of myopia in children. Investigative Ophthalmology & Visual Science. 2003;44: 1492-1500 
15. Gwiazda J, Hyman L, Norton T et al. Accommodation and related risk factors associated with myopia progression and their interaction with treatment in COMET children. Investigative Ophthalmology & Visual Science. 2004;45: 2143-2151