What is myopia?
Myopia, also known as short-sightedness, is an eye disorder that affects long-distance visual acuity while maintaining good focus on the near area. The eyeball of a myopic individual is excessively elongated, which results in the light rays concentrating in front of, rather than on, the retina, creating blurry vision. It is corrected with eyeglasses, which move the eye's focus point backward, onto the retina. Globally, myopia is reaching epidemic proportions, with 1.6 billion people already affected. By 2050, half the world's population are expected to be short-sighted. Youth onset myopia usually occurs during early school-age years and may progress until the age of 25. According to latest reports, myopia is on the rise in Southeast Asia, where the number of young people with that condition doubled in the last 30 years and has now reached 90% of individuals in that age group. According to calculations, half of the children with uncorrected myopia live in China, where their number is expected to reach 100 million in the near future.
What are the causes of childhood myopia?
- Genetic: prevalence varies according to ethnicity and family history of the condition.
- Environmental causes: greater time spent indoors and doing work that involves focusing on close objects.
What is high myopia?
High myopia describes myopia of −6 dioptres or more and can cause serious eye diseases, such as retinal diseases, including retinal detachments, age-related macular degeneration, open angle glaucoma and cataracts.
The risk of loss of vision and complications increases in proportion to the degree of myopia, with most complications occurring in people with myopia of above –10 diopters. Complications can lead to significant visual impairment and even loss of vision.
Studies on the progression of myopia in children and adolescents have shown that leaving myopia uncorrected not only did not reduce the rate of progression but in some cases even increased it. No benefits of overcorrection of myopia were found. Overall, the studies concluded that undercorrection results in a faster progression of myopia. Latest clinical practice guidelines recommend full correction of myopia. 
- medication: diluted atropine eye drops (preferably 0.01% dilution)
- optical: orthokeratology or multifocal contact lenses.
The results of the study of refractive errors in children using multifocal corrective lenses for more than 12 months did not show any significant decrease of myopia progression.
How to prevent childhood myopia?
It has been established that spending time outdoors during the day is closely related to a smaller increase in the axial length of the eyeball, which results in a decrease in myopia progression.
- Annual eye examination by an ophthalmologist from 3–4 years of age
- Children and adolescents should take regular breaks from near work: after 20 minutes of work, a 2-minute break is recommended, during which the child looks into the distance.
- Spending min. 2 hours a day outdoors with safe sunlight exposure.
Chinese guidelines for the prevention of childhood myopia include:
- spending 2 hours a day outdoors,
- no written homework during the first two years of primary school,
- maximum 60 minutes a day of written homework for children age 8-12,
- maximum 90 minutes a day of written homework for children age 12-15.
The goal is to reduce the progression of myopia by at least 0.5% over the year. 
Prof. A. Grzybowski, MD, PhD
 Logan N.S., Wolffsohn J.S.: Role of un-correction, under-correction and over-correction of myopia as a strategy for slowing myopic progression, Clinical and Experimental Optometry 2019, 1-5
 D. Kaphle, D. A. Atchison, K. L. Schmid: Multifocal spectacles in childhood myopia: Are treatment effects maintained? A systematic review and meta-analysis., Survey of Ophthalmology 4.10.2019, 1-26
 C. J. Lingxue, N. Congdon: Chinese national policy initiative for the management ofchildhood myopia, www.thelancet.com/child-adolescent, Vol 2 December 2018, 845-846