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Why would we measure axial length for an hyperopic child?

 Posted on April 3rd 2023 by Connie Gan

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In this article:

How would you manage a child with hyperopia who exhibits an axial length more like that of a myope? Read this case study.

In our Facebook community, WDJ opened a discussion about management for a moderate hyperope child with surprisingly high axial length. Would you typically measure axial length (AXL) in a child with myopic parents, and what would you do with the data? Here are the case details.

WDJ Hypothetically. Mum -5.00 dpt Dad -4.00 dpt. Kid/Boy 8 yo +2.00 without complaints AXL 24.2 mm. Would it help to correct this hyperopia to reduce growing AXL? Or should I do nothing and only advice life style? In other words, are there any studies of correcting kids with (low) hyperopia to reduce growing AXL?

Importance of axial length measurement

OW How’s your experience for having a long eye ball! Great to perform OCT regularly as well. Long AXL is definitely at high risk side for retinal issues. You need to monitor it regularly. Let’s think about 5-10 years ago. What would we do when we don’t use biometry or talk about AXL!JH What are the K’s? Very flat I presume. AXL is what counts…

Research indicates that children who are 6 years old with less than +0.75 D of hyperopia are at increased risk for developing myopia.1 Hence, can we conclude that the child is "safe" from myopia?

Refractive error is the summation of predominantly three refractive components of the eye, which are: axial length, crystalline lens power and corneal curvature. Having measured the child's axial length, we find that the results are at a much longer length than expected. For comparison, Chinese children's average axial length in emmetropia was measured at 22.93mm-23.43mmm, depending on age.2 The axial length here of 24.2mm for an 8-year-old would typically represent myopic refractive error in most other cases. As this child does not have a myopic refractive error, one would presume that this long axial length is due to flat corneal curvature, which could be confirmed with keratometry or corneal topography measurement.

How to manage this patient

HB The emmetropic AL for an 8yo is 22.8 so this is a very long eye for an 8yo. I’d be watching very closely.SDF I’d review in 6 mths. If I see more than 0.2 mm in AL, I’m using 0.05 atropine.SZ  Was under the impression that hyperopia from ≥1.5 can impact visual function and needs to be corrected in children of school age regardless of symptoms or notHK I would say measure AXL now and provided the kid is asymptomatic, document and follow.AK Plus lens Rx can helpJH ...AXL is what counts. Therapy should only be based on that and so it needs to commence.

So, how would you manage this child? The commenters have varied stances.

Firstly, should the refractive error to be corrected? According to the review article To prescribe or not to prescribe? Guidelines for spectacle prescribing in infants and children? (Table 2), children who are at least +1.50D hyperopic in the school years without symptoms are recommended to be prescribed "A full or near full correction may be given at this age, as emmetropisation has essentially ended". The article also states that hyperopia ranging from 1.00D to less than 2.00D may impact visual function and functional vision in school aged children.3

Next, as the child has a longer eyeball than the norm, his axial length needs to be monitored regularly. SDF suggests prescribing low-dose atropine if elongates more than 0.2mm per year. Should atropine be administered to a child without a myopic refractive error to slow axial growth? This would depend on informed consent and the level of concern as axial growth approached 26mm, which is a known delineator for increased risk of eye disease and vision impairment. It has been shown that axial length is the stronger predictor of future vision impairment than refractive error.4

It could be argued that with this level of hyperopia, the child is not a pre-myope. In a similar such case with lower hyperopia, check out the article Pre-Myopia And Young Age: Topical Atropine Or Not? for more information on management options.

Take home messages:

  1. Refractive error alone cannot determine whether a child is at risk for future eye disease, as this is more closely linked to their axial length.
  2. If possible, measure the axial length in all children, especially those with risk factors associated with myopia.

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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