Revolutionizing myopia management

The global surge in myopia prevalence has raised concerns among practitioners, driving the need to develop effective myopia management solutions. A lens with asymmetric myopic peripheral defocus (MPDL) has been specifically designed to address the problems related to progressing myopia which fully corrects the refractive error at the fovea while inducing a myopic defocus on the peripheral retina. Furthermore, this design is produced by means of freeform technology, eliminating the need for special semifinished products. 

The efficacy of this myopia management lens has been evaluated in the first randomized, double-blind study carried out, specifically in a European population. After 12 months of follow-up, the study demonstrated a remarkable 39% reduction in axial length progression, distinguishing this solution from conventional single vision lenses. 

In this article, this pioneering solution that utilizes freeform technology is presented with a full explanation of its lens geometry, the fundamental theories of peripheral positive/myopic defocus and asymmetric defocus as well as the clinical trial that shows the efficacy and wearer satisfaction of this solution.

Myopia prevalence is growing

Myopia is expected to become one of the leading causes of permanent blindness in the world. It is well-known that myopia prevalence is growing at an alarming rate all over the world. According to the Myopia Institute, five billion people will be myopic by 2050, and 20% of them will become highly myopic (higher than 6.00 D) with a greater risk of experiencing structural changes in the eye that can cause significant visual disability.^[1,2]

Eye care professionals around the world are concerned about the significant increase of the global prevalence of myopia and potential consequences, leading to an increased interest of practitioners to implement myopia management solutions in their routine practice.

Currently, there are some treatments available that may help to reduce myopia progression, such as spectacle lenses, contact lenses, ­orthokeratology, or eye drops. However, there is a special interest in spectacle lens options for myopia management because of their ease of use, easy acceptance by wearers, and their lack of health-related side effects.^[3]

The asymmetric myopic peripheral defocus lens

IOT has developed a lens with asymmetric myopic peripheral defocus (MPDL) that has been specifically designed to fully correct the refractive error at the fovea while inducing a myopic defocus on the peripheral retina to help slow the progression of myopia in young patients.

This defocus is achieved by a carefully designed distribution of positive power at the lens periphery that consider the morphological characteristics of the myopic retina intended to reduce myopia progression.

The characteristics of these spectacle lenses design align with the theory of creating simultaneous myopic retinal defocus during both distance and near viewing.

In uncorrected myopic eyes, images are formed in front of the retinal plane, leading to blurred vision. To correct myopia, standard single vision negatively powered lenses are prescribed to shift images onto the retinal plane. However, the peripheral defocus theory suggests that the use of standard single vision lenses results in images falling behind the retinal plane in the peripheral retina (instead of on the retina).

Different studies have hypothesized that inducing peripheral hyperopic defocus, as standard single vision lenses do, provides a stimulus for axial elongation and the consequent progression of myopia. Also, experiments in animals have shown that myopic defocus induced with positive power in the peripheral retina reduces axial elongation.^[4] 

For that reason, the lens with MPDL technology has been specifically designed to fully correct the refractive error at the fovea while inducing a myopic defocus on the peripheral retina. Furthermore, it is well known that the retina is asymmetrical. Differences between nasal and temporal retinal hemifields have been found regarding anatomical neural characteristics, peripheral refraction, and axial growth.^[5-7]

It has been suggested therefore, that sensitivity of the retina could be different between the nasal and temporal hemifields^[7] with the nasal half of the retina being more important when considering the mechanism driving eye growth in the presence of hyperopic defocus^[7] as is the case with standard single vision lenses. 

Power distribution

Following these principles, the power distribution of the lens with MPDL technology consists of a blur-free small area around the optical center providing clear and sharp central vision. The area has an ovoidal shape, with horizontal size of 7 mm and with a larger vertical dimension extending to the upper part of the lens to achieve the best balance between the treatment region and the central correction area.

The central area is surrounded by a progressive power distribution whose defocus level is modulated for the different retinal areas, with different addition power between the different regions of the lens: addition of +1.50 at 25 mm nasally, +1.80 D at 25 mm temporally, and +2.00 D at the bottom of the lens.

Additionally, thanks to the positive progressive power defocus at the peripheral areas of the design, the lens has a natural, aesthetic appearance and is thinner than a standard single-vision lens. However, the most important characteristic is the demonstrated efficacy to reduce myopia progression and the high levels of wearer satisfaction.

The study design and results

To evaluate the effectiveness of the lens with MPDL technology in reducing the progression of myopia a prospective, controlled, randomized, double-masked clinical trial led by the Universidad Europea de Madrid in a Spanish population, (clinical trial NCT05250206) and following the recommendations of the International Myopia Institute has been carried out.^[8]

The study was done in a sample of 83 children divided in two groups: 42 children wearing standard single vision lenses and 41 children wearing the lenses with asymmetric myopic peripheral defocus during 12 months of follow-up.

Results of the study showed that using the lenses with MPDL technology reduces axial length growth in comparison to the use of standard single vision lenses. Specifically, the growth of axial length was 39% less in the group wearing the lenses with MPDL technology than in the control group wearing standard single vision lenses after 12 months of follow-up.^[9]

Regarding wearability, lenses with MPDL technology scores similarly to a standard single vision lens. It obtains high satisfaction rates for all the variables analyzed, ensuring that the lens is comfortable and with high scores for wearer satisfaction.^[10]

The exceptional performance of the lens is the result of the optimal balance between the sizes of the optical correction zone and treatment areas and the use of the ideal asymmetrical power profiles for peripheral defocus. This results in a lens that provides good performance and sharpness for distance, intermediate and near vision with added wearer comfort.

Conclusion

In conclusion, lenses with MPDL technology are a novel approach to treating children’s myopia by means of an asymmetric myopic peripheral defocus lens design produced by means of freeform technology.

The efficacy and wearability of lenses with MPDL technology has been proved though a randomized, double-blind study of a 1-year clinical trial carried out in a European population, showing that after one year of treatment, the proposed lens showed an efficacy of 39% for reducing axial length growth in myopic children.

Additionally, thanks to the utilization of freeform technology, this solution ensures enhanced comfort, superior aesthetics, and a natural appearance, without the reliance on specialized semi-finished products.

References
[1] Gifford, K., Haines, C. How much axial length growth is normal? Myopia profile. 2021 
[2] Morgan, IG, Wu, PC, Ostrin, LA, Tideman, JWL, Yam, JC, Lan, W, Baraas, RC, He, X, Sankaridurg, P, Saw, SM, French, AN, Rose, KA, Guggenheim, JA. IMI Risk Factors for Myopia. IOVS. 2021;62(3):1-20. 
[3] Wolffsohn JS, Whayeb Y, Logan NS, Weng R, Weng R. IMI—Global trends in myopia management attitudes and strategies in clinical practice—2022 update. IOVS. 2023;64(6):1-15. 
[4] Lin, Zhi & Martinez, Aldo & Chen, Xiang & Li, Li & Sankaridurg, Padmaja & Holden, Brien & Ge, Jian. Peripheral Defocus with Single-Vision Spectacle Lenses in Myopic Children. OVS. 2009;87:4-9. 
[5] Curcio C. A. Allen K. A. Topography of ganglion cells in human retina. J. Comp. Neurol., 1990;300:5–25. 
[6] Logan NS, Gilmartin B, Wildsoet CF, Dunne MC. Posterior retinal contour in adult human anisomyopia. IOVS 2004;45:2152-62.
[7] Faria-Ribeiro, M., Queiros, A., Lopes-Ferreira, D., Jorge, J., & Gonzalez-Meijome, J. M. Peripheral refraction and retinal contour in stable and progressive myopia. OVS. 2013;90(1):9-15. 
[8] Wolffsohn, J. S., Kollbaum, P. S., Berntsen, D. A., Atchison, D. A., Benavente, A., Bradley, A., Buckhurst, H., Collins, M., Fujikado, T., Hiraoka, T., Hirota, M., Jones, D., Logan, N. S., Lundström, L., Torii, H., Read, S. A., & Naidoo, K. IMI – Clinical myopia control trials and instrumentation report. IOVS. 2019;60:M132–M160. 
[9] Sánchez-Tena, M.A., Cleva, J.M., Villa-Collar, C., Álvarez, M., Ruiz-Pomeda, A., Martinez-Perez, C., Andreu-Vazquez, C., Chamorro, E., & Alvarez-Peregrina, C. Effectiveness of a Spectacle Lens with a Specific Asymmetric Myopic Peripheral Defocus: 12-Month Results in a Spanish Population. Children. 2024;11(2):177
[10] Concepción, P., Cano, C., Martinez-Pérez, C., Sánchez-Tena, M.A., Álvarez-Peregrina, C., Andreu-Vazquez, C., Cleva, JM., Villa-Collar, C. Subjective wearing experience of a novel spectacle lens for myopia management based on peripheral asymmetric myopic defocus. EAOO. 2024.