Myopia Profile


Orthokeratology for anisometropia

Posted on September 18th 2023 by Connie Gan

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In this article:

Orthokeratology (ortho-k) can be a great option for anisometropes for visual function as well as myopia management. Learn how in this case study.

The standard of care for childhood myopia has changed – we now prescribe visual correction as well as manage it by reducing the risk of progression. Contact lenses are always a better choice for patients with anisometropia as they can equalize retinal image size and improve binocular vision.1 Here is a great case shared in the Myopia Profile Facebook community, involving an anisometrope managed with ortho-k lenses.


This is a fascinating case to share. This girl, of mixed Asian-Caucasian ethnicity, came to see me 3 years ago in May 2020, for her first routine eye test at age 13. She was R plano L +0.25, but as her mum was a -6D myope and a bit concerned, I took her AXL as baseline for monitoring: R 23.35mm L 23.29mm. Right on where average emmetropic AXL would be. Plano at 13 is usually a good sign, and probably low-risk for progression...

18 months later she comes back saying her RE got blurry during Covid lockdowns. Refraction R -1.75D L plano. The baseline AXL is now gold, proving it's all in axial elongation. AXL now R 24.09mm L 23.41mm. 0.74mm elongation in her RE.

She was fitted with ortho-k in her RE. Her RE axial length has stabilised over the year since. But during her year wearing ortho-k, I noticed that her untreated LE now showed signs of elongation. 0.1mm longer at each 3 month review interval. At 12 months, her AXL now measured R 23.91mm L 23.87mm. 0.46mm elongation in her LE corresponding to a -1.00D myopic shift, and she was symptomatic of the blur from her LE.

To balance her vision and to treat her LE, I added a new L ortho-k lens. 4 months later, her LE hasn't progressed any further. I find this case fascinating as it's not often that we get to see how a treated eye compares to a non-treated eye on the same individual. The effectiveness of ortho-k to arrest axial elongation is incredible to see. And while younger kids generally progress faster, teens are not immune to fast progression either.

Ortho-k can control anisomyopia

ortho-k is the only myopia control intervention which has evidence for control of myopic anisometropia: both monocular myopia and bilateral anisomyopia. One meta-analysis published in late 2021 evaluated 10 studies, most of which were retrospective, and found significant effects for ortho-k’s ability to slow axial elongation to a greater effect in the more myopic eye.

In cases of monocular myopia, eye growth in the myopic eye was slowed by a mean of 0.27mm over one year and 0.17mm over two years compared to the emmetropic eye. In cases of bilateral anisomyopia, the more myopic eye showed slower growth by a mean of 0.06mm over one year and 0.13mm over two years across the various studies.2 All of these studies were conducted in the region of Asia. None were randomized controlled trials – this would involve comparison to another type of treatment for anisometropic myopes which is not ortho-k. This means that an ‘increased efficacy’ effect can only be expressed in comparison to the other eye of these anisometropic myopes.


ortho-k has evidently shown to yield the remarkable clinical efficacy, particularly for anisometropic cases in general.


I find fascinating the way anisomyopia initially occurred and how it sort of balanced itself later. The ortho K mid term effectiveness is a bit too early to judge. But the short term seems impressive.

The mechanism for this is unknown. It has been shown that higher baseline myopia can be associated with slower axial elongation in ortho-k wearers.3,4 This does not mean ortho-k is less effective for lower myopes – those with higher myopia may be older or have other factors related to myopia stability, and not all studies have found this same result. The significant optical changes induced by ortho-k, which would be larger for a more myopic treatment, could drive this beneficial effect on anisomyopia.3

Ortho-k has a long history of research in myopia control, indicating robust efficacy and safety outcomes.5 In this case, the patient exhibited stability of axial length over a year wearing ortho-k in her right, myopic eye, while at the same time her left, emmetropic eye showed elongation of 0.1mm per 3 months, and progression into myopia. Fortunately, the eye care practitioner acted quickly to fit ortho-k to the patient’s newly myopic left eye, so she can benefit from myopia control for this eye as well. 

Take home messages:

  1. Anisometropia is better to treated with contact lenses than spectacles.
  2. Ortho-k lenses are an ideal choice for myopia management with a strong evidence base, and is the only treatment which shows evidence for slowing axial elongation in the more myopic eye of patients with anisometropia.

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 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 Kimberley also manages our Myopia Profile and My Kids Vision Instagram and My Kids Vision Facebook platforms.

This content is brought to you thanks to unrestricted educational grant from


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