Axial Length Measurement for Myopia Control

Many people are surprised to learn that myopia, aka nearsightedness, is a progressive condition. Patients who have myopia can see nearby objects clearly but find that they get blurrier the further they are away from your eyes. Unfortunately, your first set of prescription lenses to improve your vision are unlikely to be your last. This is because the axial length of your eyes is likely to change over time, making your vision worse. That is unless you have treatment to control your myopia.

 

What is Axial Length?

The axial length measurement refers to a combination of three individual elements. These are anterior chamber depth, lens thickness, and vitreous chamber depth. Myopia normally results from an increase in the axial length measurement that is outside the expected rate for the patient’s age. 

The measurement of axial length has been established as a crucial measurement in studies looking at the progression and control of myopia. This is because myopia is caused by a dysfunction between the optical power of the eye and its length. Measuring the AXL of the eyes has been proven to provide a more accurate indicator of myopia progression and control than refraction, particularly where the patient is undergoing orthokeratology treatment where the refraction is intentionally altered. In fact, in this instance, the axial length measurement may be the only parameter that can be used as a gauge of myopia control outcomes.  For example, a change of just 1mm in axial length could result in a myopic shift of between 2.00 to 2.50D. This is significant and warrants a change in prescription.

The Importance of Myopia Control

Although myopia doesn’t seem like a serious condition, it is important to keep it under control and stop it from progressing as much as possible. This is because high levels of myopia have been linked to increased risk of complications relating to eye health and vision in adulthood. Studies have also shown that the onset of myopia in childhood, particularly before the age of 10, results in a higher risk of high myopia in adulthood.

Some of the conditions that are more likely if a patient has high myopia include:

Glaucoma: a condition characterized by raising intraocular pressure that causes pressure on the optic nerve, permanently damaging patient vision. Moderate and high myopia has been associated with an increased risk of glaucoma. Although there is treatment for glaucoma, any vision lost cannot be restored.

Cataracts: this eye disease occurs when the natural lens of the eye becomes clouded, preventing the patient from seeing clearly. Cataracts occur when the proteins of the lens clump together, causing patches that are like looking through frosted glass. Some research has shown that high myopia increases the risk of developing cataracts. The only way to restore the vision of patients with cataracts is to undergo surgery to replace the lens with an artificial alternative.

Retinal detachment: another sight-threatening condition which is where the retina comes away from the other tissues, preventing messages from being sent up the optic nerve to the eyes. One study has shown that around 55% of retinal detachments are attributable to myopia. Any vision lost as a result of retinal detachment cannot be restored.

 

Controlling Myopia

Fortunately, there are a number of different options available for controlling the progression of myopia, which may be able to keep it at low to moderate levels. Myopia control is recommended to start in childhood, which gives the patient the best chance at avoiding high myopia in the future. Treatments include topical options such as eye drops, to special contact lenses that stop the extension of the axial measurement, carefully managing the degree of myopia that the patient experiences. Speak to your eye doctor to find out more about the myopia control treatments that may be suitable for your child. 

Experts agree that patients with myopia must be monitored closely, which is one reason why patients are recommended to attend annual eye exams with their eye doctor. If you have any further questions about myopia, axial length measurement for myopia control, or if you would like to make an appointment, please speak to our expert team in Rosedale Auckland.