Considering myopia control

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Research article from Michael J Lipson

With friendly permission from Michael J Lipson

Prevalence of myopia in the United States has increased to about 40 percent over the last 30 years.In East Asia, prevalence is about 75 percent and in some countries as high as 90 percent.2,3 Eyecare practitioners are diagnosing myopia at younger ages than we have seen in the past.4,5 Incidence of high myopia (>5.00 D) is increasing and carries with it risk for vision-threatening problems such as myopic macular degeneration, retinal detachment, glaucoma, and cataracts.6,7

Why are we seeing higher incidence of myopia, higher degrees of myopia, and earlier age of diagnosis? Research into the answers to these questions has come up with a variety of influences, but because the changes have been observed over such a short time (25 to 30 years) genetics cannot be the only factor.
Contributing risk factors identified for myopia development and myopia progression include:
• Family history8

• Time spent outdoors9,10

• Time spent on near work11,12

• Age of onset13

• Refractive status at specific age13

• Ethnicity14,15

• Binocular vision status16

Michael J Lipson

OD FAAO FSLS 
Department of Optometry, University of Michigan, USA

Contact : mjlipson@med.umich.edu

Dr. Michael Lipson is an optometrist/assistant professor in the Department of Ophthalmology and Visual Science at University of Michigan’s Kellogg Eye Center.  His clinical practice involves contact lenses with emphasis on specialty contact lenses for overnight corneal reshaping, keratoconus, post-corneal transplant, post-refractive surgery and severe dry eye patients. He is actively involved in clinical research as the principal investigator for studies on corneal reshaping, vision-related quality of life, myopia control and new lens designs.

Efforts to control the progression of myopia have been studied in the past. But recent awareness of the seriousness of myopia and the number of patients affected has spawned a volume of studies on the various methods we have to slow myopic progression that are detailed below. They include environmental, optical (multifocal contact lenses, orthokeratology [ortho-k] contact lenses), and pharmaceutical.
Before prescribing myopia control techniques for your patients, keep in mind two important points. First, although the published data shows variable amount of control for each method, no single method is best for all patients. It is a custom and ongoing process that requires careful follow-up. Second, none of these methods currently have FDA approval for the indication of myopia control. As such, when prescribing these methods of myopia control, you are prescribing them for an off-label indication.

Optical

The accepted theory of optical control of myopia progression is based on creating myopic defocus on the retina peripheral to the macula.17,18  This is best accomplished using multifocal contact lenses or ortho-k.
Other optical methods employing specially-designed spectacles, multifocal spectacles or under-correction with spectacles have been studied in questionable study designs yielding highly variable results. Those will not be discussed in this article.

Orthokeratology

The corneal changes during ortho-k produce a 4 mm to 6 mm central flattening surrounded by a ring of steepening (Figures 1 and 2). The central flattening reduces the refractive myopia and improves unaided visual acuity that allows patients to be free of correction during their waking hours. The surrounding ring of steeper curvature creates an area of myopic defocus peripheral to the macula that creates the myopia control effect.
Numerous studies have been conducted to determine how much ortho-k slows myopic progression. One recent study  showed that 65 percent of children using ortho-k showed little or no increase in axial length over a three-year period.19 A meta-analysis of various studies on the myopia control effect of ortho-k shows that ortho-k slows myopic progression by 40 to 60 percent.20

As an example, with a 50 percent reduction in myopia progression, an 8-year-old, 2.00 D myope who may progress to an 8.00 D myope by age 18 would be at 5.00 D at age 18 if eyecare practitioners started ortho-k at age 8. At first, that may not seem significant, but in light of the risks of high myopia mentioned above, it reduces that patient’s risk of retinal detachment by 12 times and myopic macular degeneration by 30 times (Table 1). Also, a 5.00 D myope is more functional without correction than an 8.00 D myope.

The advantages of using ortho-k for controlling myopic progression are:

• The optical effect is in play 100 percent of the time during waking hours

• Most patients show significant slowing of myopic increases

• Patients are generally very compliant with regular wear.Patients like being able to function without correction during the day and adapt to the routine of nightly wear quickly and easily

There are two potential downsides to ortho-k. First is the ongoing risk of corneal irritation from debris trapped under the lens during overnight wear. Fortunately, this is rare and can be minimized with careful lens cleaning and handling routines. Second is that the peripheral myopic defocus increases spherical aberration. This is generally not a problem in children but, in some patients, can cause more glare during low light conditions.

Multifocal contact lenses

Soft multifocals

This mode of myopia control is based on the same optical effect mentioned above with ortho-k, peripheral myopic defocus. With soft multifocal lenses, a center-distance design provides good focus centrally to correct myopia while the plus power peripherally creates the myopic defocus outside of the macular area. Data on the myopia control effect using this modality show widely variable results, with one study showing 25 percent reduction in myopic progression to another study showing 80 percent slowing of myopia progression.21Interestingly, other multifocal designs (center near, multi-zone and aspheric) have also shown myopia control effects.
Ideal candidates for soft multifocal lenses include children with low myopia who can be responsible enough to wear lenses during the day without direct parental supervision. Disposable multifocal lens are readily available, safe and affordable. Significant astigmatism requires use of custom toric multifocals.

Disadvantages of soft multifocal lenses are that lenses must be worn for almost all waking hours to be effective.

Gas permeable multifocals

Similar to the soft multifocal designs, gas permeable (GP) multifocals can create peripheral myopic defocus in aspheric or concentric designs. The advantage of GP lenses is that astigmatism is corrected via the GP optics.
The biggest challenge with GP lenses worn during the day is that adaptation to lens awareness is longer. Again, lenses must be worn for most waking hours. But the numerous design options provide a flexible option for a variety of prescription challenges.

Michael J Lipson

Pharmaceutical

Atropine (non-selective anti-muscarinic agent) eye drops have been used as a method of controlling myopic progression for many years, particularly in East Asia. Initially, it was thought that the mechanism of atropine’s efficacy was based on its cycloplegic effect. Recently, it has been shown that the myopia control effect of atropine is from its action in the retina and choroid.22
Since this was determined, clinical evaluations of lower concentrations of atropine (0.5%, 0.25%, 0.1%, and 0.01%) have been performed. One study showed that 0.01% atropine had a greater long-term (4 years) myopia control effect than 1.0% atropine.23
Atropine is used once a day at bedtime. Its myopia control effect has been quite effective, but the unwanted side effects (difficulty reading and light sensitivity) of 1.0% atropine make it difficult for many patients to remain compliant with ongoing treatment. Those side effects are not clinically evident with concentrations of 0.02%  or less.24
Long-term control of myopia progression (more than 5 years) with atropine is not yet known.
There are questions regarding a rebound effect of increased rate of myopic progression following discontinuation of atropine use. That being said, it is highly useful in very young children who are not candidates for ortho-k or soft lenses.
Atropine can be prescribed in conjunction with the optical methods described above. Studies on the combined myopia control effects of multiple treatment modalities are ongoing.
Similarly, but less effective, pharmaceutical activity has been observed with pirenzepine (an M1 selective anti-muscarinic agent). Note that pirenzepine is not available in the United States.

Time outdoors

You can prescribe a specified number of hours outdoors that your patient should spend each week. A meta-analysis showed that “at-risk” children who spend 14 hours per week outdoors (two hours per day) can delay the onset of myopia.25
Once myopia has been diagnosed, results have been mixed regarding whether outdoor time can slow its progression.

Reducing near work

In combination with increasing time outdoors, guidelines should be established for conducting near work. Guidelines should include limitation on number of hours spent on near tasks, frequent “vision breaks,” good posture, good lighting, and added distance from the screen (both TV and computer).26

Incorporating myopia control

A summary of myopia control studies with various methods is shown in Figure 3. With the mounting evidence that we can slow myopic progression, the eyecare community has been slow to adopt these methods and prescribe them regularly. The ideal time to initiate myopia control is before children become myopic.
A recent publication of an international survey of eyecare practitioners showed a mismatch between our profession’s perception and our actions.27 While clinical practitioners thought that single-vision spectacles and under-correction were the least effective methods of controlling myopic progression, a majority still prescribe single-vision spectacles or contact lenses as the primary correction modality.
Before optometrists can convince patients that myopia control is important, we must convince our profession that the practice of myopia control should become a standard of care.

First published at optometrytimes.modernmedicine.com/optometrytimes

References

1. Vitale S, Sperduto RD, Ferris FL 3rd. Increased prevalence of myopia in the

United States between 1971-1972 and 1999-2004. Arch Ophthalmol. 2009 Dec;127(12):1632-9.

2. Bloom RI, Friedman IB, Chuck RS. Increasing rates of myopia: the long view. Curr Opin Ophthalmol. 2010 Jul;21(4):247-8.

3. Kim EC, Morgan IG, Kakizaki H, Kang S, Jee D. Prevalence and risk factors for refractive errors: Korean National Health and Nutrition Examination Survey 2008–2011. PLoS One. 2013 Nov 5;8(11):e80361.

4. Chua SY, Ikram MK, Tan CS, Lee YS, Ni Y, Shirong C, Gluckman PD, Chong YS, Yap F, Wong TY, Ngo CS, Saw SM; Growing Up in Singapore Towards Healthy Outcomes Study Group. Relative Contribution of Risk Factors for Early-Onset Myopia in Young Asian Children. Invest Ophthalmol Vis Sci.     

2015 Dec;56(13):8101-7.

5. Jones-Jordan LA, Sinnott LT, Manny RE, Cotter SA, Kleinstein RN, Mutti DO, Twelker JD, Zadnik K; Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) Study Group. Early childhood refractive error and parental history of myopia as predictors of myopia. Invest Ophthalmol Vis Sci. 2010 Jan;51(1):115-21.

6. Flitcroft DI. The complex interactions of retinal, optical and environmental factors in myopia aetiology. Prog Retin Eye Res. 2012 Nov;31(6):622-60.

7. Holden BA, Jong M, Davis S, Wilson D, Fricke T, Resnikoff S. Nearly 1 billion myopes at risk of myopia-related sight-threatening conditions by 2050 - time to act now. Clin Exp Optom. 2015 Nov;98(6):491-3.

8. Kurtz D, Hyman L, Gwiazda JE, Manny R, Dong LM, Wang Y, Scheiman M; COMET Group.. Role of parental myopia in the progression of myopia and its interaction with treatment in COMET children. Invest Ophthalmol Vis Sci. 2007 Feb;48(2):562-70.

9. French AN, Ashby RS, Morgan IG, et al. Time outdoors and the prevention of myopia. Exp Eye Res.2013 Sep;114:58-68.

10. Guggenheim JA, Northstone K, McMahon G, Ness AR, Deere K, Mattocks C, Pourcain BS, Williams C. Time outdoors and physical activity as predictors of incident myopia in childhood: a prospective cohort study. Ophthalmol Vis Sci. 2012 May 14;53(6):2856-65

11. Lin Z, Vasudevan B, Ciuffreda KJ, Wang NL, Zhang YC, Rong SS, Qiao LY, Pang CC, Liang YB. Nearwork-induced transient myopia and parental refractive error. Optom Vis Sci. 2013 May;90(5):507-16.

12. Lin Z, Vasudevan B, Mao GY1, Ciuffreda KJ, Jhanji V, Li XX, Zhou HJ, Wang NL, Liang YB. The influence of near work on myopic refractive change in urban students in Beijing: a three-year follow-up report. Graefes ArchClin Exp Ophthalmol. 2016. Nov;254(11):2247-2255.

13. Zadnik K, Sinnott LT, Cotter SA, Jones-Jordan LA, Kleinstein RN, Manny RE, Twelker JD, Mutti DO; Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) Study Group. Prediction of Juvenile-Onset Myopia. JAMA Ophthalmol. 2015 Jun;133(6):683-9.   

14. Logan NS, Shah P, Rudnicka AR, Gilmartin B, Owen CG. Childhood ethnic differences in ametropia and ocular biometry: the Aston Eye Study. Ophthalmic Physiol Opt. 2011. Sep;31(5):550-8.

15. Ip JM, Huynh SC, Robaei D, Rose KA, Morgan IG, Smith W, Kifley A, Mitchell P. Ethnic Differences in the Impact of Parental Myopia: Findings from a Population-Based Study of 12-Year-Old Australian Children. Invest Ophthal Vis Sci. 2007 Jun;48(6):2520-8.

16. Gwiazda J, Thorn F, Held R. Accommodation, accommodative convergence, and response AC/A ratios before and at the onset of myopia in children. Optom Vis Sci. 2005 Apr;82(4):273-8.

17. Smith EL 3rd, Hung LF, Huang J. Relative peripheral hyperopic defocus alters central refractive development in infant monkeys. Vision Res. 2009 Sep;49(19):2386-92.

18. Smith EL 3rd, Kee CS, Ramamirtham R, Qiao-Grider Y, Hung LF. Peripheral vision can influence eye growth and refractive development in infant monkeys. Invest Ophthalmol Vis Sci. 2005 Nov;46(11):3965-72.

19. Lipson MJ, Harris JK, Lather HD, Niziol LM, Musch DC. Axial Length in Orthokeratology Patients: Large Case Series. Adv Ophthalmol Vis Syst. 2016 Nov;5(2):00154.

20. Si JK, Tang K, Bi HS, Guo DD, Guo JG, Wang XR. Orthokeratology for myopia control: a meta-analysis. Optom Vis Sci. 2015 Mar;92(3):252-7.

21. Aller TA, Wildsoet C. Results of a one-year prospective clinical trial (CONTROL) of the use of bifocal soft contact lenses to control myopia progression. Ophthalmic Physiol Opt. 2006;26(Suppl.):8-9.

22. McBrien NA, Stell WK, Carr B. Point-counterpoint. How does atropine exert its anti-myopia effects? Ophthalmic Physiol Opt. 2013 May;33(3):373-378.

23. Chia A, Chua WH, Cheung YB, Wong WL, Lingham A, Fong A, Tan D.Atropine for the treatment of childhood myopia: safety and efficacy of 0.5%, 0.1%, and 0.01% doses (Atropine for the Treatment of Myopia 2). Ophthalmology. 2012 Feb;119(2):347-54.

24. Cooper J, Eisenberg N, Schulman E, et al. Maximum atropine dose without clinical signs or symptoms. Optom Vis Sci. 2013 Dec;90(12):1467-72.

25. Sherwin JC, Reacher MH, Keogh RH, Khawaja AP, Mackey DA, Foster PJ. The association between time spent outdoors and myopia in children and adolescents: a systematic review and meta-analysis. Ophthalmology. 2012 Oct;119(10):2141-51.

26. Jones-Jordan LA, Sinnott LT, Cotter SA, Kleinstein RN, Manny RE, Mutti DO, Twelker JD, Zadnik K; CLEERE Study Group. Time outdoors, visual activity, and myopia progression in juvenile-onset myopes. InvestOphthalmol Vis Sci. 2012 Oct;53(11):7169-75.

27. Wolffsohn JS, Calossi A, Cho P, Gifford K, Jones L, Li M, Lipener C, Logan NS, Malet F, Matos S, Meijome JM, Nichols JJ, Orr JB, Santodomingo-Rubido J, Schaefer T, Thite N, van der Worp E, Zvirgzdina M. Global trends in myopia management attitudes and strategies in clinical practice. Cont Lens and Anterior Eye. 2016 Apr;39(2):106-16.

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