Myopia is a refractive error (blurred vision at a given distance) that affects around 30 per cent of the world’s population. This proportion is increasing so quickly that it is estimated it will reach 50 per cent by 2050.
The United States-based National Academy of Sciences (NAS) recently changed the way myopia is defined. NAS now considers myopia to be a disease rather than a refractive error. This shift reflects the scientific understanding that high myopia, a more severe form of the disorder, can potentially cause significant pathological changes.
As an optometrist, this new classification concerns me directly because it changes the standard of care of patients with myopia.
What does it mean for public health agencies and governments?
Read more: Épidémie de myopie chez les jeunes : haro sur la techno !
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When myopia is considered a pathology
Linking myopia to pathology prompted the World Health Organization (WHO) in 2019 to define the condition as a major risk factor for so-called preventable blindness. This decision was based on the work of Dr. Ian Flitcroft, an Irish ophthalmologist, and consensus by international experts.
Flitcroft demonstrated that any myopic person is at risk of ocular pathology, and that this risk increases proportionally with the degree of myopia.
It is important to understand that a myopic eye is an eye that lengthens and stretches beyond its average length of 24 millimetres. This characteristic poses a threat to its structure, especially the retina. As a result of this elongation, the retina and other ocular structures can suffer breaks and tears.
Glaucoma and cataracts can occur more quickly, and their association with high myopia makes their treatment much more complex.
The main condition that can lead to blindness in nearsighted people is myopic maculopathy, which can develop particularly when the axial length of the eye exceeds 26 millimetres.
This condition is characterized by cracks in the macula, the central part of the retina that provides the most precise vision and contains our best cells (photoreceptors). These cracks irreversibly reduce visual acuity. Legal blindness can occur when blood vessels and hemorrhages complicate the picture, somewhat like wet macular degeneration.
A public health issue
Fortunately, there are effective optical (specific glasses or contact lenses, with optical profiles causing defocus at the periphery) and pharmacological (low-dose atropine) solutions for slowing the progression of myopia.
It’s possible to slow down or modulate the elongation and stretching of the retina, reducing the risk of myopic maculopathy and of penalizing visual impairment. This is the origin of the term “preventable blindness” used by the WHO.
Each degree of myopia (diopter) that is prevented reduces the risk of myopic maculopathy by 40 per cent, which represents a very powerful initiative, unparalleled in terms of public health.
Indeed, it is estimated that the overall cost associated with the direct care and indirect costs of myopia, including loss of productivity, amounted to US$244 billion in 2015. Correcting and better controlling myopia from progressing reduces this financial burden.
So myopia has been officially recognized as a disease, and the different means to control its evolution are have also been validated. The direct and indirect economic impacts have also been estimated and shown to be a significant cost to society.
Consequently, the reasons why all stakeholders must now fight against the onset of myopia and its progression have become clear.
Mobilizing various players
The World Council of Optometry has stated that controlling myopia should now be considered a standard of practice. The World Society of Pediatric Ophthalmologists recognizes the value of controlling myopia as well as the merits of means to do so, and encourages ophthalmologists to use them.
Canada recently adopted the National Strategy on Eye Care Act. It states that the Canadian government, in collaboration with the provinces and other stakeholders, must “support the prevention and treatment of eye disease, as well as vision rehabilitation, to ensure better health outcomes for Canadians.”
The fight against myopia should be a natural part of this new approach. In addition, starting now, governments should explore avenues that would make it possible to reach agreements with health professionals to cover the cost of eye examinations for children (which is not the case in all provinces).
Part of the cost of the required equipment, such as specially designed anti-myopia glasses and specialty contact lenses and medication (atropine), should also be covered. To that end, the Québec program See Better to Succeed is already a step in the right direction.
Although they are more expensive than standard myopia correction lenses, these optical devices effectively slow down myopia and, as a result, prevent its harmful consequences. Unfortunately, they are too costly for many families.
That puts children from less privileged backgrounds at a disadvantage. That also means that their educational and employment prospects are reduced compared to children from privileged backgrounds who get proper treatment. In other words, their quality of life is diminished and their future is penalized from start.
Myopia is therefore being seen as a public health issue and a vector of social inequality. Decision-makers should take note and act accordingly.
