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  • Writer's pictureLawrence i-Care Optometrists

Why Size Matters (when it comes to Myopia Management), or at least, axial length does...

So as the title of this article states, size really does matter when it comes to Myopia Management - or at least axial length does...

So what is Axial Length and why does it matter?

According to the College of Optometrists latest guidance, Optometrists should:

"Consider how you will measure outcomes. Axial length monitoring is the preferred method to assess stabilisation or progression of myopia, especially in orthokeratology".

The college also offers an alternative saying "If this is not available, you should undertake cycloplegic autorefraction and keratometry to provide an estimate of axial length."

It finally notes "Cycloplegic autorefraction also provides an objective and repeatable measure of refractive status at baseline and follow-up visits, but this result should not be used to prescribe optical interventions. Refractive error evaluated in isolation without axial length measures will not provide as sensitive an indication of success (or lack of success) of myopia management interventions."

So to paraphrase the statement above, the College of Optometrists considers Axial Length to be a key part of Myopia Management.

But what is Axial Length?

In general, when we are born, the distance from the front to the back of the eye which is known as the axial length, is around 16mm. By the time we reach adulthood, axial length of the eye has typically grown to some 24mm.

Most of the growth occurs in our early childhood years, with the changes being most rapid during the first ten months of life.

Generally, the changes to the various eye surfaces and axial length will stay in ratio to keep vision clear for distance. In some people though, the eyes will grow longer than they should, or the surfaces become steeper than they should.

When the surfaces and axial length is within its normal boundaries, light focuses on the retina, enabling us to see clearly.

If the axial length extends beyond its normal length, then the point at which light is focused within the eye may move in front of the retina.

As a result, it becomes harder to see objects clearly at a distance. This is known as myopia or short-sightedness, specifically axial myopia.

Because the eye grows fastest in childhood, in most cases, this is when myopia is most likely to develop and is why our team of Optometrists will regularly monitor axial length (and any changes in axial length), where relevant, in our patients.

(We typically recommend periodic screening with additional screening after any sudden 'growth spurts').

Understanding these changes and any other potential trigger points helps our clinicians to identify to parents whether their child might be starting to develop myopia.

Parents can then discuss with our optometrists the options available that could help slow down their child's myopia progression.

If you think your child may have myopia, or they are struggling with their vision or school work contact us as soon as possible to arrange an appointment with one of our clinicians.

Tel (+44) 01342 323463

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