The chances of being born with Myopia are very small. So much so that in one 2019 study  of newborn babies, just 0.45% were identified as having Myopia at birth with 95.2% diagnosed with hyperopia. This is a condition in which visual images are focused at a virtual point behind the retina, leading to close up images appearing blurry.
In the early stages of a baby’s development that hyperopia tends to reduce rapidly. That’s because the axial length (the distance from the front to the back of the eye) grows at pace over the first year. The average axial length for a new-born is in the region of 16.8mm compared to 23.6mm in adults.  By the end of the first year that axial length increases to 20.6mm, rising to 21.4mm by the age of three.  Slower rates of axial length growth are generally then seen until an individual reaches adulthood.
Putting it in simple terms, that increase in the axial length helps to move the focal point forwards, reducing the Hyperopia and moving towards normal vision (also called Emmetropia). However, in some cases the axial length keeps growing thereby shifting the focal point on again towards Myopia.
Myopia may even develop in adulthood due to factors such as too much close work. However, it is far more likely for Myopia to start to manifest in childhood. The age at which Myopia is likely to develop does vary from individual to individual with risk factors such as parental Myopia, amount of close work, or time spent outdoors having an impact.
For example, one study  concluded that:
an increase of 76 minutes a day spent outdoors compared with their baseline sample could result in a 50% reduction in the incidence of Myopia, but had less of an effect in children who had already developed Myopia.
Another study  concluded that the odds of developing Myopia increased by 2% for every extra hour of close work per week.
Generally childhood Myopia starts to occur around the age of three with parents or teachers starting to notice a vision problem somewhere between the ages of four and six. That’s one reason why in the UK a child’s health and development reviews which take place when children are one year old and again at between the ages of two and two and a half are so important. They can help to identify potential problems at an early stage, far before formal vision screening takes place at the age of four or five. And the earlier a problem is identified, the sooner therapeutic interventions can take place. But, it is clear that screening for childhood myopia needs to occur in all children of all ages.
If you're a parent whose child has been diagnosed with myopia, or if they are struggling with their distance vision, we hope you found MyopiaFocus helpful. Please join our community or sign our petition to get the government and NHS to recognise myopia as an ocular disease/serious ocular condition and fund myopia management for children.