Myopia Profile

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Is it myopia progression or early keratoconus?

 Posted on September 26th 2021 by Connie Gan

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Paediatric keratoconus has faster rate of progression and is typically more severe at diagnosis when compared with adult keratoconus.1 There is also a correlation between keratoconus and axial myopia so it is not unusual to see the two conditions coexist.2,3 Here, BS shared with the Myopia Profile Facebook community a case of a 12-year-old progressing myope with early keratoconus.

BS Hey profilers! I just had an interesting case to share with the group: 10-year-old boy who started with Misight in Dec 2018 with an Rx of R&L -2.25DS, there was a change to -2.50DS in Dec 2019 (AXL R23.45mm L23.45mm). June 2020: Rx progresses to R-3.25DS L-3.00DS (AXL R23.67mm L23.73mm) Assumed to be a change due to increased NV and lockdown conditions. Dec 2020: Rx progresses again to R-3.75DS L-3.50DS (AXL R23.79mm L23.82mm) I have a lot of patients on MiSight and there have only been a couple who have progressed during the lockdown. The child has been studying intently for school entrance exams. This level of change is unusual compared to the rest of my patients. I speak to the mother, who has just learnt that two of her siblings have keratoconus. When I look back to the Ks Jun 2020: R7.11x7.31 L7.03x7.20 (similar to previous readings) Dec 2020: R:6.97x7.20 L7.03x7.20 (also some minor irregularity/steepening at the inferior cornea R>L) The child has now been confirmed to have early keratoconus with the possibility of crosslinking being investigated. (VAs dropped from 6/6 to 6/7.5 over the past 6 months) So the progression of myopia has an element of keratoconus. I'd be really interested in your thoughts about options for myopia management in this case. Misight is giving adequate vision but would a multifocal RPG be more suitable should the VA drop further? Is there evidence for Ortho-K in keratoconus?BS I did a couple of cyclo RXs. The last one in Dec 2020 R-3.75/-0.50x180 L-3.50/-0.75x180 There wasn't a cyl greater than -0.75 (x180). No scissor

Is the change in refractive error due to axial length or a steepening cornea?

This case highlights the value of axial length measurements in understanding myopia progression. The child's axial length has increased by R 0.34mm and L 0.37mm over a two year period, while the refraction has increased by R -1.50D and L -1.25D in the same time. Considering that typical axial elongation in emmetropic children is 0.1mm per year on average,4 it could be presumed that 0.2mm of this total axial progression is 'normal' with the remaining R 0.14mm and L 0.17mm over two years indicating only a small amount of myopia progression.

KG …Roughly, because the Rx-to-AXL relationship is still a bit woolly, there’s around 0.50D progression in two years due to AXL (great MiSight result actually!) but R -1.50 L -1.25 of refractive progression. (R 0.34 L 0.39mm change in two years, subtracting 0.2 normal AXL growth for two years) Managing his acuity and his myopia will be equally important. There’s no myopia control studies in kids with impaired BCVA - they’re excluded. Again, great case, highlighting the importance of considering other factors in fast progression!

The axial length measurements become invaluable in this case as it clarifies the axial component of the refractive error change. The ratio of axial length to refractive error change in children is not conclusively defined, being somewhere around 2D per mm - read more in Six questions on axial length measurement in myopia management. Hence, as KG has highlighted, the total axial elongation over two years is equivalent to around 0.50-0.75D of myopia progression which is much less than the observed refractive progression. Something else has contributed to the refractive change - the steepened cornea, as detected in the astute measurement of the post author.

Corneal curvature doesn't typically change during school-aged childhood myopia progression,5 so any measured steepening is a red flag for potential ectasia.

What can we do?

1. Continue current treatment while acuity is maintained

KG ...Despite minimal evidence that OK could be contraindicated in very early KC, SCL seems best option to be safe and controlling myopia. As you've rightly said, if acuity deteriorates you'll need an RGP. But there are no studies on MF RGPs for myopia control and no designs like MiSight, to my knowledge (they'll be more like centre D MF)...BS …For now it's a question of regular and frequent monitoring and continuing with Misight until there's more corneal changes or reassessing after cross linking, if that's performed. It's a case of regular monitoring and seeing if there are RGP options just in case.

At the early stages of keratoconus, one can continue prescribe glasses or soft contact lens if the patient can achieve a good level of vision. As the child is still achieving good acuity from a myopia controlling soft contact lens (MiSight), commenters suggest maintaining the current strategy including after cross-linking is done, as depicted below.

SS To me nothing to discuss here at this stage except the speed that cross linking can be done. You appear to have shown progression of cone so in this age cross linking is urgent in my opinionBS I agree. I believe that the consultant wants to monitor over 2-3 months and then likely to perform cross linking. I've shared my data. What happens after cross linking? Myopia vs keratoconus managementAY … I wouldn't be able to add to anything, but my personal feeling would be to stick to MiSight after having crosslinking done as soon as allowed. It's going to be in the patient's best interest to preserve VA and not just axial length, after all!

Since myopia control studies typically exclude children with reduced acuity or any ocular health condition, the continued efficacy of a myopia control treatment in this child is unknown. Clear communication about this with the child's parents is important.

2. Consider other options for now and the future

If keratoconus worsens, a switch to rigid gas permeable lenses (RGPs) may be necessary to improve functional vision and best-corrected acuity.6 In this case, the correction would be single vision - the use of RGPs with modified optics for myopia control hasn’t been well researched in the normal population, let alone in people with keratoconus. Pauné et al describe a novel RGP lens design that induces peripheral myopic defocus to help in myopia control but its efficacy has not yet been tested.7

From a myopia control perspective, conventional wisdom suggests avoiding fitting orthokeratology lenses to ectactic corneas. To learn more about the very small amount of literature on OK and early or suspect keratoconus, read Should I Fit Orthokeratology Lens To A Potential Keratoconic?

3. Provide advice on managing keratoconus progression

KP Is the patient an eye rubber, was at OSI meeting last year and French consultant… was talking about how just stopping eye rubbing (eye shields at night etc etc), help a lot of his patients…

As the child is not yet proceeding with cross linking treatment, frequent follow ups are necessary to monitor changes in refractive error and best-corrected acuity. Since keratoconus is often associated with allergic/vernal keratoconjunctivitis and eye rubbing, providing advice on this and managing any ocular allergy can help in reducing the rate of progression.6

Take home messages:

  1. Paediatric keratoconus progresses faster than adult keratoconus, hence intervention should start as early as possible.
  2. In this case, seeing a small amount of axial length progression over two years helped to indicate that the refractive progression was not just axial. Determining that the cornea was contributing to myopic refractive change was only possible through measurement - taking keratometry readings and/or corneal topography measurements in progressing myopes is best practice.
  3. Myopic patients with impaired best-corrected acuity are typically excluded from myopia control studies, so clear communication with parents is necessary to set expectations for myopia control.

Read more on how axial length fills in the clinical picture

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.

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

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