WHO Publishes Findings on Myopia

According to the report, an agreement on the standard definitions of myopia and high myopia was important so that “internationally comparable, accurate data on the prevalence of myopia and high myopia can be obtained”. The consultation also provided the opportunity for delegates to “categorise myopic defects, evaluate the evidence on myopia control strategies and identify gaps in knowledge to be urgently filled so that evidence-based strategies to reduce the prevalence of high myopia and associated vision impairment”. 

Definitions of Myopia and High Myopia

The WHO report defined myopia as “a condition in which the spherical equivalent objective refractive error is ≤ –0.50 diopter (–0.50 D) in either eye”.

High myopia was defined as “a condition in which the spherical equivalent objective refractive error is ≤ –5.00 D in either eye”.

Reducing the rate of myopia progression by 50 per cent could reduce the prevalence of high myopia by up to 90 per cent

The report defined myopic macular degeneration (MMD) as “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”.

When working with limited resources and in remote locations, delegates agreed the definition of MMD would be “vision impairment and vision acuity that are not improved by pinhole and cannot be attributed to other causes, and direct ophthalmoscopy records a supplementary lens: ≤ –5.00 D and changes such as ‘patchy atrophy’ in the retina, or ≤ –10.00 D”.

Myopia was reported to be associated with higher risks of glaucoma and cataract but may be protective against age-related macular degeneration and diabetic retinopathy.

Myopia Prevalence

The report identified that global prevalence of myopia and high myopia affect an estimated 27 per cent (1893 million) and 2.8 per cent (170 million) of the world population, respectively, in 2010, with prevalence of myopia highest in east Asia, where China, Japan, the Republic of Korea and Singapore have a prevalence of approx. 50 per cent. Prevalence was lower in Australia, Europe and north and south America.

The authors wrote that myopia and high myopia would affect 52 per cent (4949 million) and 10.0 per cent (925 million), respectively, of the world’s population by 2050. These preliminary projections were based on prevalence data, the corresponding United Nations population figures, and accounting for the effects of age and time.

The importance of reducing myopia was clear in the finding that, “Reducing the rate of myopia progression by 50 per cent could reduce the prevalence of high myopia by up to 90 per cent.

Myopia control

Among many findings reported by WHO were:

• Recent reports show under correction is associated with a higher rate of progression of myopia.
• Some initial published evidence indicates that time spent outdoors can delay the onset and perhaps reduce the progression of myopia, although more research is required, as it is also potentially a risk factor.
• There is published evidence that excessive near work increases the risk of myopia.
• There is published evidence that multifocal spectacles can slightly reduce the rate of progress of myopia; executive bifocal lenses are associated with substantially larger reductions.
• Specially designed contact lenses that reduce peripheral hyperopia and/or create significant myopic defocus can slow the progress of myopia.
• Orthokeratology can slow the progress of myopia, but overnight wear of contact lenses is associated with risks.
• Low-dose atropine has been shown to be effective in reducing the progression of myopia but not in slowing the rate of increase of axial length (more research is required)
• Larger clinical trials are needed to establish safety and efficacy of other agents suggested for the control of myopia, such as 7-methylxanthine.

The 2016 Brien Holden Vision Institute Global Scientific Meeting on Myopia was held at University of New South Wales, Sydney, Australia. The three-day meeting was initiated by the Minister of Health for Australia, the Right Honourable Mr. Peter Dutton, who contacted the Director General of WHO, Dr Margaret Chan to request WHO’s involvement. Scientific and clinical experts in myopia from all six WHO regions were invited to attend the meeting.

Visit www.brienholdenvision.org to read the full report, titled Impact of Increasing Prevalence of Myopia and High Myopia – A Report of the Joint World Health Organization.