Is Under-Correcting Myopia Helpful to Prevent Myopia Progression?

Kristi Sharma, B.Optom

M.Optom student, The Sankara Nethralaya Academy, Chennai, India

 

Introduction

Myopia is a type of refractive error in which the image of an object we see, forms in front of the retina rather than falling on the retina.(Figure 1) This eventually causes blurring of distance vision. Myopia is a rising concern regarding vision and its progression brings up multiple ocular complications like maculopathy and retinal detachment. Various methods of myopia control are being practiced widely which includes ortho-keratology, multi-focal contact lenses, myopia control spectacle glasses and atropine treatment. Talking about refractive corrections, we have learned and applied practically on patients with myopia an under-corrected prescription power for quite a long time. But is under-correcting helpful in preventing myopia progression or is it in-turn making the condition worse?

Figure 1: Image formation in myopic eye
(Image courtesy: All About Vision, https://www.allaboutvision.com/conditions/myopia.html)

Review of Literature

In a randomized two year controlled clinical trial in 2002 by Chung et al. it was reported that under correction of myopia, increased myopia progression rate in myopic children.⁽¹⁾ A similar study conducted in 1965 showed that the mean change in refractive error is significantly less in under-corrected group of myopic patients compared to the fully corrected once, but later the data in this study was found to be flawed.

In 2006, Adler et al in their study reported that under-correction does not represent an effective therapy to slow down the rate of early‐onset myopic progression, regardless of near heterophoria.⁽²⁾ Under-correction produced a slight progression over the 18-month period compared to full correction.⁽²⁾

Again, in 2014, Vasudevan et al conducted an analysis of clinical refraction data where they found that there was a significant positive correlation between magnitude of under-correction and myopic progression, which means higher the under-correction, more the progression.⁽³⁾

Koumbo Ornella in 2019 concluded in their study that under-correction of myopia can lead to elongation of the eye because of the presence of blurry vision at any distance thereby, resulting in the increased progression of myopia.⁽⁴⁾

A review paper published by Yazdani et al. in 2021 compared the effect of full correction and under-correction on myopia progression.⁽⁵⁾ They came to the conclusion that myopic eyes that were fully corrected with non-cycloplegic refraction were less prone to myopia progression compared to those which were under corrected. ⁽⁵⁾

In another study by Logan et al, it was concluded that there was no strong evidence of benefits from under-correction, monovision and over-correction and stated that current clinical advice advocates for the full correction of myopia.⁽⁶⁾

Figure 2: Myopia Correction with spectacles
(Image courtesy: Optician Online)

Conclusion

Thus, many studies have surfaced today to shower light upon how under-correcting myopic patients actually leads to increased progression of myopia, contradicting the old belief that it helped in reducing progression. We too should keep this in mind while correcting any myopic patients in the clinic to help them reduce their myopia progression and keep their refractive error as stable as possible.

 

References

1. Chung K, Mohidin N, O’Leary DJ. Undercorrection of myopia enhances rather than inhibits myopia progression. Vision research. 2002 Oct 1;42(22):2555-9.
2. Daniel Adler, Michel Millodot. The possible effect of undercorrection on myopic progression in children. Clin Exp Optom. 2006 Sep;89(5):315-21. doi: 10.1111/j.1444-0938.2006.00055.x.
3. BalamuraliVasudevana, Christina Espositoa, Cody Petersona, Cory Coronadoa, Kenneth J. Ciuffreda. Under-correction of human myopia- Is it myopigenic?: A retrospective analysis of clinical refraction data. J Optom. 2014 Jul-Sep;7(3):147-52. doi: 10.1016/j.optom.2013.12.007.
4. Chung K, Mohidin N, O’Leary DJ. Undercorrection of myopia enhances rather than inhibits myopia progression. Vision research. 2002 Oct 1;42(22):2555-9.
5. NegarehYazdani, RaminSadeghi, AsiehEhsaei, Ali Taghipour, Samira Hasanzadeh, LeiliZarifmahmoudi, JavadHeravianShandiz. Undercorrection or Full Correction of Myopia? A meta analysis. J Optom. 2021 Jan-Mar;14(1):11-19. doi: 10.1016/j.optom.2020.04.003.
6. Nicola S Logan, James S Wolffsohn. Role of un-correction, under-correction, and over-correction of myopia as a strategy for slowing myopic progression. Clin Exp Optom. 2020 Mar;103(2):133-137. doi: 10.1111/cxo.12978.