Myopia Profile

Clinical

Communicating with parents about axial length

 Posted on August 8th 2022 by Connie Gan

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In this article:

Slowing axial length growth is the key goal in myopia management. Read how to communicate with parents about axial length.

"Axial length" is a terminology with which many parents may not be familiar. The most common quantifier of myopia for eye care practitioners and parents alike is refractive error. Here is a case by LM about how adding axial length measures to the clinical discussion can change the picture of a child's myopia and the decision to commence myopia control treatment.

LM Just to confirm the importance of AL measurement in Myopia control. Consult of the day. Teenager 14 years old. Case hx: patient wants contact lenses to play soccer 3 times a week. Looking for daily disposable lenses and regular single vision glasses for the other days. Looking at the chart: evolved from -0.75 to -2.25 in 3 years. Was offered by my colleague in general clinic 2 times to consider myopia management. Mom declined every time.. with no further details. (I suspect cost issue was there) I confirmed Rx OD -2.50 OS -1.75. .. still evolving...Discussed myopia evolution, use of computer in this pandemic era, reading distance, lighting, etc. Mom open to discuss these details and their potential impact (in fact I just confirmed what she told her daughter for the last 6 months..) And I ended my exam with AL measurement, Got 25.72 OD and 25.53 OS !!!! Not expected to say the least. I just explained that over 26, it represents a risk for ocular pathology over 60 year old. Mom suddenly convinced to do something, NOW she said !!!, and the girl went out with soft MF lenses instead of SV DD ones... AL measurement saved my day!

Axial length is the key measurement in myopia control

OW Agreed. I had been using biometry and axial length to explain the eyes conditions now and the future in the last 15+ years to most of myopic patients. This helped me so much in executing the myopia management treatment plan. There’re still lots of people only know “D” and no idea about “mm”! I think it’s our responsibility to explain and educate them about the potential danger and risks of an elongated eye ball! Early intervention is strongly encouraged. Biometry machine has been my most use equipment daily now. CH Axial length measurements have been a game changer in my practice. Has changed the way I look at myopia control and that’s saying something because I have been doing this myopia control thing since 1985!TM If you ask group of 100 myopia managing doctors that measure and discuss axial length with their patients, I am nearly certain all 100 would say it's been extremely important in patient education to treating more patients. It's also just good for business!UTJ Agree! Axial length measurement is one of the key measurement to show evidence of change - parents doesn't see urgency when seeing refractive change only.

The commenters agreed on the invaluable benefits of measuring axial length in myopia management. Excessive axial length growth increases the risk of eye diseases associated with myopia such as retinal detachment and myopic macular degeneration, and increase the risk of visual impairment.1 Hence, as eye care practitioners, we have the responsibility to make sure that parents are educated on this important 'why' of myopia management.

It has been shown that less than half of parents consider that myopia presents a health risk to their children.2 In addition, another study showed 88% of parents are unaware of complications associated with high myopia.3 On the more positive side, 66% of parents were willing to commence myopia management after watching educational videos about myopia control options.3 This indicates the value of parental education - minds can be changed with the right information provided.

How axial length drives treatment decisions

DS Do you think that the risk would be different for a -2.75D 25.7mm eye compared to a -5.00D 25.7mm eye. I’ve noticed the wide variation in axial lengths at each dioptric step in our data.LM  I would say that it is about the same risk. Eye stretching generates pathology. This is why dioptres really don't matter. I would look more at the age of myopia onset as well. Nicer curves are explicit on the fact that starting early means the progression will last longer and risk is higher.LM Part of the answer may come from the analysis that was made by Tideman in 2018 (see reference Tideman et al) - when he published growth curves. If you look at this chart, for Caucasian males. Let say that you have 3 kids with 23 mm AL; the 3 of them having various refractive errors. At 6 years old, the kid lies over the bold line- there is a risk of high myopia at 7%. Kid #2 is 8 years old and lies on the bold curve- 50% percentile- no risk of high myopia. 3rd kid at 12 years old is under the bold curve and is not at risk in the future. Myopia control in this case may be optional. Based on this study, at least, refraction does not play a major role in the risk for high myopia and associated pathology. It is true that habitually longer eyes are more myopic but this reminds us that it is not always the case. My moto: treat one kid at a time. Customization. The kid in your chair is everything but an average.

Whilst refractive error has a correlation with axial length, it is possible for patients to have long axial lengths with low levels of myopia. This is important clinical information, as in this case, axial length data may change a parent's perception on the urgency of instigating myopia management. As diagnostic instruments to measure axial length are increasingly used in primary eye care, this becomes an invaluable tool in practice. Percentile growth curves are becoming more commonplace to assess and quantify the risk of a child's myopic progression.4 To learn more, read How to use axial length growth charts.

Take home messages:

  1. Axial length data can be an invaluable tool to illustrate the 'why' of myopia management, especially in cases where the axial length is approaching 26mm.
  2. Parental education is key for a child's access to myopia control strategies.
  3. Children with low myopic refractive error can still register long axial length readings, so recommendations for myopia control is still imperative in this cohort.

Further reading

Meet the Authors:

About Connie Gan

Connie is a clinical optometrist from Kedah, Malaysia, who provides comprehensive vision care for children and runs the myopia management service in her clinical practice.

Read Connie's work in many of the case studies published on MyopiaProfile.com. Connie also manages our Myopia Profile and My Kids Vision Instagram and My Kids Vision Facebook platforms.

About Kimberley Ngu

Kimberley is a clinical optometrist from Perth, Australia, with experience in patient education programs, having practiced in both Australia and Singapore.

Read Kimberley's work in many of the case studies published on MyopiaProfile.com. Kimberley also manages our Myopia Profile and My Kids Vision Instagram and My Kids Vision Facebook platforms.

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