Impact of myopia and high myopia

Myopia: Prevalence and impact.

1. THE IMPACT OF MYOPIA AND HIGH MYOPIA Report of the Joint World Health Organization–Brien Holden Vision Institute Global Scientific Meeting on Myopia

2. Citation The impact of myopia and high myopia: report of the Joint World Health Organization–Brien Holden Vision Institute Global Scientific Meeting on Myopia, University of New South Wales, Sydney, Australia, 16–18 March 2015. Geneva: World Health Organization; 2017. Licence: CC BY-NC-SA 3.0 IGO. © World Health Organization 2017 2 Impact of Myopia and High Myopia

3. Myopia Aristotle (384-322 BC) Credited with first distinguishing myopia Galen (131-201 AD ) Derived the term ‘myopia’ Myopia = myein (“too close”) and ops (“eye”) Results when an eye has excessive refractive power for its axial length. 3 Impact of Myopia and High Myopia

4. 4 Impact of Myopia and High Myopia

5. Global prevalence of myopia Global Burden of Disease E stimates: URE the leading cause of moderate and severe vision impairment (53%) and the second largest cause of blindness [ 1] . 2010: Myopia and high myopia were estimated to affect 27% (1893 million) and 2.8% (170 million) of the world population [2 ] . Prevalence : Highest in East Asia (approx. 50 %) and lower in Australia, Europe and north and south America. 5 Impact of Myopia and High Myopia

6. Figure 1: Numbers of cases (blue) and prevalence (red) of myopia worldwide between 2000 and 2050 6 Impact of Myopia and High Myopia

7. Figure 2 : Numbers of people worldwide with high myopia (blue) and prevalence (red) between 2000 and 2050 7 Impact of Myopia and High Myopia

8. The WHO Projections 2050 2050: Prevalence will be ≥ 50% in 57% of the countries, if current trends continue. 2050: Countries in which the prevalence of myopia has been estimated and measured as low in the past (e.g. India) will have major increases. 2050: Myopia will be much higher in high-income regions of the Asia- Pacific, in east Asia and in south-east Asia 2050: A bout 30% of Africa will be similar to that in Asia today. 2050: The prevalence of high myopia is predicted to increase to 24% in all the Global Burden of Disease regions Footnote: The WHO model for projections was based on regional structure 8 Impact of Myopia and High Myopia

9. Terminology M yopia “a condition in which the spherical equivalent objective refractive error is ≤ –0.50 dioptre (D) in either eye”. H igh myopia “a condition in which the spherical equivalent objective refractive error is ≤ –5.00 D in either eye”. . Examples: 1. -2.00/-6.00 x 180 2. +2.00/-6.00 x 180 9 Impact of Myopia and High Myopia

10. Pathologic myopia Clinical Definition: Not well defined, with different descriptions across studies of vision-threatening changes in the retina or the presence of posterior staphyloma , and various criteria for axial length and spherical equivalents refractive error. Acceptable definition: High myopia with signs of retinal atrophic changes (5 ). Approximately 1% of whites and 1–3% of Asians C auses more VI or blindness in Asians (0.2–1.4%) than in Caucasians (0.1–0.5%) 10 Impact of Myopia and High Myopia

11. Myopic macular degeneration (MMD) C linical definition: A vision-threatening condition in people with myopia, usually high myopia, which comprises diffuse, patchy macular atrophy with or without lacquer cracks, choroidal neovascularization and Fuchs spot. It was agreed that the direct ophthalmoscope lens power wheel should be used in rapid assessments. Currently, choroidal neovascularization in MMD is managed by treatment with anti-VEGF. 11 Impact of Myopia and High Myopia

12. Myopic macular degeneration Source: Hayashi et al [ 33 ] 12 Impact of Myopia and High Myopia

13. Progression of MMD in a group of people with high myopia (≤ -8.00) 13 Impact of Myopia and High Myopia

14. A proposed international photographic classification and grading system for MMD 14 Impact of Myopia and High Myopia Footnote: No universal grading system for MMD is in use clinically.

15. WHO recommendations for care and management of pathologic myopia Pathologic myopia: Patient should have access to a full range of eye-care services. For myopic CNV: Anti VEGF may be considered, but the long-term prognosis for vision is unknown. Increased risk for glaucoma: Glaucomatous optic neuropathy should be investigated. Increased risk of RD and cataract : F undus and anterior segment examination is essential. If VI is uncorrectable : Patient should have access to comprehensive eye-care services, including vision rehabilitation and appropriate devices and surgery if necessary. 15 Impact of Myopia and High Myopia

16. Impact of myopia 1. Myopia as a cause of VI and blindness Under corrected myopia: The most common cause of VI, as judged by presentation for poor visual acuity. Uncorrected myopia as low as –1.50 D will result in moderate VI, and uncorrected myopia of –4.00 D can cause blindness [ 36 ] . MMD: The most common cause of VI in myopia. 10% of people with pathologic myopia develop MMD (due to choroidal neovascularization), which is bilateral in 30% of cases [ 16 ] . Myopia: Associated with higher risks of glaucoma and cataract but may be protective against ARMD and DR. High myopia: Can cause serious, sight-threatening retinal damage. 16 Impact of Myopia and High Myopia

17. 2 . Economic Implication Global loss of productivity due to URE : I$ 269 billion per annum [ 14 ] E stimated cost of addressing the problem : US $ 28 billion over 5 years [ 15 ] Expected 4.9-fold increase in high myopia by 2050. The cost of care is also likely to increase significantly . Singaporean Study [37-38] The annual direct cost of optical correction of myopia for Singaporean adults has been estimated at US$ 755 million. The direct cost of myopia in Singaporean children was US$ 148 per child per year. If the available data were extrapolated to all cities in Asia, the estimated direct cost would be US$ 328 billion. 17 Impact of Myopia and High Myopia

18. 3. Impact on quality of life and personal development Adolescents with myopia: Reported lower scores for total quality of life, psychosocial functioning and school functioning [ 39 ] . Correction of refractive errors by the provision of spectacles in low socioeconomic areas markedly improve educational outcomes [ 40 ] . The major contributors to the burden of eye disease at the global level are refractive errors (27.7 million DALYs) followed by cataract (17.7 million DALYs) [20]. 18 Impact of Myopia and High Myopia

19. 3. Burden on global eye care services Increased prevalence of high myopia I ncrease in pathologic myopia increased VI and blindness Increased burden on ophthalmological and low-vision services. 19 Impact of Myopia and High Myopia

20. Evidence for causes of myopia 1. Optical and environmental influences Several optical and environmental factors have been identified as possible causes of the onset and progression of myopia, acting either individually or in combination. 1.1 Peripheral hyperopic defocus The pattern of peripheral refraction varies with central refraction (43,44). Myope : Have relative hyperopia in the periphery, can increase ocular growth Hyperope : H ave relative myopia in the periphery, can cause slow axial elongation 20 Impact of Myopia and High Myopia

21. Association between central and peripheral refraction 21 Impact of Myopia and High Myopia

22. 1.2. Intensive near work (45,46): T he mechanism by which near work increases axial length is the combined influence of biomechanical factors (i.e. extraocular muscle forces, ciliary muscle contraction) associated with near tasks in downward gaze. 1.3.Time spent outdoors (47 ): E pidemic of myopia in East Asia is primarily due to changes in environmental (social) factors, specifically intensive education and less time spent outdoors. Observed seasonal variation in the progression of myopia adds weight to the argument that time spent outdoors slows the progression of myopia. 22 Impact of Myopia and High Myopia

23. Five-year risk of incident myopia among six-year-old Australian children 23 Impact of Myopia and High Myopia

24. ( Dashed lines = Mechanical Tension Theory ; Dotted lines = Accommodative Lag Theory; Solid line = common to both theories) 24 Impact of Myopia and High Myopia

25. Genetics and parental history Genetics and the environment play a role in the development and progression of myopia, but the genetic contribution is considered small. T here is consensus that genes may determine susceptibility to environmental factors (50). The rapid increase in the prevalence of myopia seen over a short time in east Asia (54, 55, 56) cannot be explained by genetics. In the twin study by He et al., baseline refraction and parental myopia were found to be risk factors. 25 Impact of Myopia and High Myopia

26. Control of Myopia Optical control 1.1 Spectacle methods Leaving myopia uncorrected: Does not reduce the rate of progression (65). Undercorrection : S hown to increase myopia progression. Due to peripheral and central blur, stimulating axial growth Progressive addition lenses: Have a small, statistically significant effect. The reduction is correlated with the degree of relative myopia produced in the superior retina by near addition (69). Executive bifocals: with a +1.50 addition and 3 D base-in prism reduced the rate of myopia progression by 57% (62 ). Reduces the stimulus for axial elongation. 26 Impact of Myopia and High Myopia

27. 1.2 Contact lens methods Standard RGP : Do not reduce the rate of myopic axial elongation. Bifocal contact lenses: Reduced progression (spherical equivalent of refractive error and axial length). Act by reducing accommodative lag ( 73) Orthokeratology : Consistent reduction in myopia progression of approximately 45% over a two-year period and 30% over five years, when measured in terms of axial length (63). Extended depth-of-focus lenses : S upport the myopic defocus hypothesis ( 76 ). 27 Impact of Myopia and High Myopia

28. 2. Time spent outdoors and behavioural influences Evidence is emerging that spending more time outdoors can protect against the onset of myopia. Sufficient time outdoors (more than two hours/day ): Reduced the risk of myopia, even when they had two myopic parents and continued to perform near work (77). Indoors playing sports not beneficial. The nature of the outdoor activities does not seem to be critical (77). The mechanism of action of time spent outdoors remains unknown and requires further investigation. Hypothesized that the sunlight stimulates the release of dopamine from the retina, which inhibit axial elongations ( 81, 82). Seasonal differences: Progression is faster in winter and slower in summer (83 ). Outdoor activity could be made part of obesity reduction campaigns for children, and schoolchildren in particular. 28 Impact of Myopia and High Myopia

29. 3. Pharmacological and therapeutic control 3.1 Atropine Atropine reduces myopia progression in children in a dose-related manner, but a rebound effect (“catch-up”) occurs with higher doses (85). Atropine at 0.01% : Lower doses, 0.01 % , reduce the common side-effects observed with the higher dose. Resulted in a 59% reduction in the rate of progress of myopia, with minimal adverse effects; however, controversially, it had no effect on axial elongation (85). Recently approved by the FDA for long-term amblyopia therapy in children. Currently no regulatory approval for the use of atropine to slow myopia progression 29 Impact of Myopia and High Myopia

30. Clinical guidelines for children aged 6–10 years with myopia > 1.0 D and documented myopia progression > 0.5 D per year 30 Impact of Myopia and High Myopia Clinical guidelines are needed on who should be treated, when treatment should begin and cessation and the duration of treatment.

31. 3.2 7–methylxanthine A non-selective adenosine antagonist. Affects the release of neurotransmitters such as dopamine, norepinephrine , acetylcholine, glutamate and serotonin (86). Danish Study 8-years of follow-up of 750 myopic reported no side-effects. Dose of 400 mg twice a day reduced myopia progression by 60% (70). 31 Impact of Myopia and High Myopia

32. Recommendations for myopia control 1. Access to correction: Essential to avoid VI. 2. Full correction of myopia 3. More outdoor activities 3. Less near work 4. Contact lenses and ortho -k 5. PALs 7. Low-dose atropine 32 Impact of Myopia and High Myopia

33. Research There is a large body of research on myopia. However, few areas requires further research: Epidemiology of myopia Myopigenesis , environmental, optical and therapeutic factors Risk factors and individual heterogeneity High myopia, pathologic myopia and comorbid conditions Eye examinations in myopia 33 Impact of Myopia and High Myopia

34. Key messages On the basis of current estimates and demographic trends, myopia is the main cause of distance refractive error and will probably continue to be so in the future. If the increasing prevalence of myopia is not addressed, a similar increase in URE can be expected . Reducing the rate of myopia progression by 50% could reduce the prevalence of high myopia. On the basis of the evidence, that myopia warrants national and international synergistic efforts, as the costs and public health implications are huge and often underestimated [2]. 34 Impact of Myopia and High Myopia

35. Conclusions Documented increases in the prevalence of myopia and high myopia worldwide are a serious public health concern . Data to inform research, clinical practice and public health policy must be produced urgently. C onsistent use of international terminology for obtaining internationally comparable, accurate data on the prevalence of myopia and high myopia. M yopia and high myopia should be included as attributable causes of vision impairment in epidemiological surveys. T he term “myopic macular degeneration” should be used to categorize the blinding retinal diseases associated with high myopia. 35 Impact of Myopia and High Myopia

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38. 38 Happy weekend  Impact of Myopia and High Myopia

39. Regions defined in the WHO Global Burden of Disease programme 39 Impact of Myopia and High Myopia

40. Lag of Accommodation Lag of Accommodation : The amount by which the accommodative response of the eye is less than the dioptric stimulus to accommodation. 40 Impact of Myopia and High Myopia