Screening for myopia in NZ?

Myopia is the most common ocular problem internationally and prevalence is increasing. Research suggests myopia currently affects 23% of the world population, with estimates of 49% affected by 2050. The World Health Organisation identifies myopia within its top five priority eye diseases. Increasing prevalence is linked to environmental factors, including near work activities and decreased outdoor time. Genetic predisposition is important but can’t explain the short-term rise in prevalence.

Myopia increases risk of irreversible vision loss through cataract, glaucoma, retinal detachment and myopic macular degeneration. Petty and Wilson¹,² suggest the risks associated with myopia in New Zealand are underappreciated by the medical, educational and public health community. Current treatment is aimed at correcting refractive error, rather than preventing axial length elongation. Attempting to prevent myopia progression offers an opportunity to decrease the burden of myopia on individuals and wider society.

We used the Wilson and Jungner criteria to examine the need for screening for childhood myopia in New Zealand and found it met nine out of 10 criteria.

  1. The condition sought should be an important health problem
    • Myopia is an important health problem
  2. There should be an accepted treatment for patients with recognized disease ✔
    • Optical, behavioral, and pharmacological treatments eg. low dose atropine
  3. Facilities for diagnosis and treatment should be available ✔
    • Alterations could be made to the current year 7 (age 11) school screening programme
  4. There should be a recognisable latent or early symptomatic stage ✔
    • Myopia can be identified at an early stage through photorefraction
  5. There should be a suitable test or examination ✔
    • Photoscreening offers an easy, fast, affordable, reliable, non-invasive test
  6. The test should be acceptable to the population ✔
    • Photoscreening is acceptable to the population
  7. The natural history of the condition, including development from latent to declared disease, should be adequately understood ✔
    • We have adequate understanding
  8. There should be an agreed policy on who to treat as patients X
    • Further research needs to establish robust treatment guidelines
  9. The cost of case finding (including diagnosis) should be economically balanced in relation to possible expenditure on medical care as a whole ✔
    • Estimates suggest a $202 billion global GDP loss due to uncorrected refractive error. The cost of case finding is unlikely to be high given already available screening services
  10. Case finding should be a continuing process and not a “once and for all” project ✔

Current national vision screening guidelines published in 2014 state two purposes: to identify children with amblyopia at an age when treatment might be effective; and to identify and refer children with reduced visual acuity for further assessment. Screening consists of visual acuity testing at the ‘B4 School Check’ (<age 4) and ‘Year 7 vision screening’ (age 11). Referrals are made to optometrists or ophthalmologists if screening requirements are not met.

Conclusion

We suggest that adjustments are made to the year 7 (age 11) service to incorporate childhood myopia screening. This would involve introducing autorefractors and appropriate reduction of the screening age. Robust treatment guidelines are required, aimed at reducing myopia progression through optical, behavioural and pharmacological methods. The International Myopia Institute released its Clinical Management Guidelines report in February 2019. The New Zealand Myopia Action Group plans to establish New Zealand specific guidelines and discuss feasibility with the Ministry of Health and the National Screening Advisory body.

Reference

  1. Holden B, Fricke T, Wilson D, et al. Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050. Ophthalmology. 2016 May;123(5):1036–42.
  2. Petty A, Wilson G. Reducing the impact of the impending myopia epidemic in New Zealand. NZMJ. 2018;131:1487

Ben Wilkinson works as a non-training ophthalmology registrar at Gisborne Hospital.

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