Myopia is usually described as blurry distance vision. That's true, but it's only the surface. Underneath, myopia is a story about how the eye grows, and that story is why we look far beyond the prescription.
It's easy to think of myopia purely as an inconvenience: distance vision blurs, glasses fix it, done. For adults with stable, low myopia, that's often close enough to the whole story. Our Myopia overview covers how glasses, contact lenses and OrthoK correct that blur day to day.
But myopia isn't caused by a fault in the lens or cornea the way a scratch or a cataract is. It's caused by the eyeball itself growing a little longer than it should, and that distinction matters enormously, especially in a child whose eyes are still developing. A longer eye isn't just a number to correct. It's a structural change that stays with someone for life.
Genetics load the gun. A child with one myopic parent has a higher chance of developing myopia, and that risk climbs further with two myopic parents. But genetics alone doesn't explain what we're seeing: myopia rates have risen sharply over just a few decades, far too quickly for our genes to have changed.
That points squarely at environment. Children today spend more hours on near work, screens and study, and comparatively less time outdoors than previous generations, and both of those shifts are consistently linked to higher myopia rates. Genetics decides who's most susceptible; environment increasingly decides who actually develops it, and when. We unpack the evidence behind this in detail on our Preventing Myopia page.
Two numbers describe a myopic eye. Only one of them tells you what's actually happening structurally.
The number on a prescription. It tells you how much optical power is needed to correct vision today, but on its own it doesn't reveal how the eye is growing.
The physical, front-to-back length of the eyeball. This is the structural cause of myopia, and the measurement we monitor most closely as your child grows.
Two children can share an identical prescription yet have different axial lengths, and the one with the longer eye carries higher lifetime risk, regardless of what the prescription says. Prescription can also plateau temporarily while the eye keeps elongating underneath it. That's why every dioptre, and every millimetre, is treated as meaningful data rather than just a number to correct.
A single visit tells us your current prescription. A series of visits, measured consistently, tells us how your eyes are actually behaving.
We measure the current prescription and examine overall eye health, checking for anything beyond a simple refractive error.
A fast, non-contact scan measures the eye's true length to a fraction of a millimetre, giving us the structural baseline every future visit is compared against.
Corneal topography and retinal imaging round out the picture, and are especially useful if OrthoK is being considered or if higher myopia warrants a closer look at the retina.
The most important step isn't any single visit, it's the pattern across visits. Comparing axial length and prescription over months and years tells us whether an eye is stable or still progressing, and whether a treatment is actually working.
Myopia is one of four common refractive errors. Hyperopia (long-sightedness) blurs near vision when the eye is too short. Astigmatism blurs vision at all distances due to an irregularly curved cornea. Presbyopia is the age-related loss of near focusing that affects almost everyone from their forties onward.
Myopia stands apart because, in a growing child, it's genuinely progressive: the underlying cause, an elongating eye, tends to keep advancing until growth finishes. That's the reason myopia gets dedicated attention that the other refractive errors typically don't need. Our refractive errors overview compares all four side by side.
A comprehensive myopia assessment gives you more than a prescription. It gives you axial length data, a clear picture of progression risk, and a plan tailored to your child.