Extended Depth of Focus as a Myopia Control Strategy

Kristi Sharma, B. Optom

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

 

Introduction

Myopia is one of the highest talked about ocular conditions in the present scenario, given the increasing prevalence of its progression along with the complications involved with the same. Many different modalities of myopia control measures are being developed with an objective of halting the progression to the highest extent possible. In the contact lens options available, we often talk about Ortho-keratology and Multifocal contact lenses, with their efficacy extensively studied and reported. However, there exists another type of contact lens, the concept being developed not too long ago, that is showing promising results in controlling the issue at hand.

Extended Depth of Focus (EDOF) contact lenses are used for managing presbyopia as well as for myopia. It may be described to be a type of multifocal contact lens, although there is a significant difference in the optical profile of these lenses.⁽¹⁾

Optics of EDOF Contact Lens

Unlike multifocal contact lenses, EDOF lenses increase the depth of focus to cover a larger range of focal points, so that vision at different distances remains above a quality threshold level. This basically means that these lenses enable the wearers to focus clearly on different distances. The optics of these lenses aims to avoid the usual flaws in the simultaneous view designs of multifocal designs.⁽²⁾

EDOF Design for Myopia Control

For the purpose of myopia control, EDOF lenses used have a centre-distance design. It is based on the peripheral defocus theory, that correct distance vision in the central retina and prevent the rays from focusing behind the retina (hyperopic defocus) in the retinal periphery, thereby slowing axial length elongation.⁽¹⁾

EDOF contact lenses can manipulate spherical and other higher order aberrations to create a specific optical effect. The designs utilise higher order aberrations in the front surface to elongate the focal point.^(1,2)

Evidence in Literature

Bakaraju et al. reported that EDOF lenses significantly reduced the rate of progression of myopia in children aged 8 to 13 years in their study conducted in 2014 in China.⁽³⁾ In another case series analysis, it was found that EDOF contact lens was effective in slowing myopia progression in children aged 6 to 9 years.⁽⁴⁾ Similarly, the study conducted by Sankaridurg et al. reported that myopia progression is slowed in the cases while compared to the controls after two years of the clinical trial.⁽⁵⁾

Conclusion

Myopia progression is a global concern at present and various strategies have been implemented that have shown successful results in preventing the progression. Every emerging control method is shown to have a positive impact in slowing down the progression of the refractive condition. However, studies are still in process to develop more effective methods and increase the efficacy of myopia control to manage this pandemic at the rise globally.

 

References

1. Gifford, K. (2022). What does extended depth of focus mean in contact lens designs? Myopia Profile. https://www.myopiaprofile.com/articles/extended-depth-of-focus-contact-lenses
2. Kramer, E. (2022). Extended Depth of Focus Optics: Discover How These New Devices Can Expand Your Patients’ Visual Horizons. Presbyopia Physician. https://presbyopiaphysician.com/issues/2022/march/discover-how-these-new-devices-can-expand-your-patients-visual-horizons
3. Bakaraju, R. C. (2015). Extended depth-of-focus contact lenses can slow the rate of progression of myopia. Investigative Opthalmology and Visual Science.https://iovs.arvojournals.org/article.aspx?articleID=2331450
4. Cooper, J., OʼConnor, B., Watanabe, R., Fuerst, R., Berger, S., Eisenberg, N., &Dillehay, S. M. (2018). Case Series Analysis of Myopic Progression Control With a Unique Extended Depth of Focus Multifocal Contact Lens. Eye & contact lens, 44(5), e16–e24. https://doi.org/10.1097/ICL.0000000000000440
5. Sankaridurg, P., Bakaraju, R. C., Naduvilath, T., Chen, X., Weng, R., Tilia, D., Xu, P., Li, W., Conrad, F., Smith, E. L., 3rd, &Ehrmann, K. (2019). Myopia control with novel central and peripheral plus contact lenses and extended depth of focus contact lenses: 2 year results from a randomised clinical trial. Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists), 39(4), 294–307. https://doi.org/10.1111/opo.12621