New Leading-Edge Technology for Myopia Control

Aakanksha Pathania, Optometry Student

Intern Optometrist, Chaudhary Eye Centre & Laser Vision, New Delhi, India

 

Background

Myopia, often termed as near-sightedness, is a refractive anomaly of the eye, where the parallel rays coming from infinity converge in front of the retina when accommodation is relaxed. ⁽¹⁾ Evidence states that 30% of the world is currently myopic and is expected to increase up to 50% by 2050, which if left untreated, will lead to blindness. ⁽²⁾

With increasing screen time, myopia control is one of the significant challenges in today’s world. Myopia progresses in children as our eyes continue to grow while we age. Hyperopic retinal blur due to high accommodative lag during near work is another cause of axial elongation. Several options such as orthokeratology, 1% atropine eye drops, executive bifocal, and progressive lenses are used for myopia control. ⁽³⁾ The new methods in the fight against myopia are Defocus Incorporated Multiple Segments (DIMS) and Highly Aspherical Lenslet Target (HALT) lenses.

DIMS and HALT technology use peripheral myopic defocus treatment to control axial elongation. In myopia, while the central rays fall in front of the retina, the peripheral one goes beyond the retina thus creating a hyperopic defocus which results in myopic progression. ⁽⁴⁾

DIMS technology is developed by Hong Kong Polytechnic University. It works on the concept of creating simultaneous defocus. It comprises a central 9mm optic zone for correcting distance refractive errors and multiple focal zones with 33mm in diameter and multiple segments each of 1.03 mm in diameter having a relative positive power(+3.50D) resulting in myopia defocus. Research data shows around 50% refractive and 60% axial length efficacy with DIMS. ⁽⁵⁾

Figure 1: Myopia Defocus Zone Which Controls Myopia Progression
(Figure source: https://www.crayfordoptical.com/node/37)

HALT technology is developed by Essilor, where light rays instead of focusing on two distinct surfaces, deviate continuously in a nonlinear manner by a spherical front surface with 11 concentric rings formed by contiguous aspherical lenslets having a diameter of 1.1 mm around the clear optical zone, that creates a three-dimensional quantity of light in front of the retina, which is called the volume of myopic defocus (VoMD). It is generated in front of the retina at any eccentricity and serves as a myopia control signal. Research data shows around 70% refractive and 60% axial length efficacy for HALT. ⁽⁵⁾

Figure 2: Standard lenses only correct myopia and Essilor Stellest lenses correct and control myopia
(Figure source:  https://www.emmevisioncare.com/myopia-control)

Myo-Kids by Zeiss is a customised lens that controls myopic progression by controlling accommodative lag during near vision tasks while providing clear and comfortable vision at all distances. Reducing accommodative lag is known to result in a potential reduction of myopia progression. ⁽⁶⁾
Like spectacles, Cooper Vision developed MiSight 1day disposable lenses that control myopia progression. It has concentric rings around the lens that create myopia defocus to slow eye elongation. It has two treatment zones that create myopic defocus with image focus in front of the retina, rather than behind it, to slow axial elongation and two correction zones which correct myopia in all gaze positions.

Figure 3: Treatment zone correcting myopia defocus and Correction Zones
(Figure Source: https://coopervision.com/practitioner/our-products/misight-1-day/misight-1-day)

All these designs have a peripheral defocusing zone for controlling the progression while at the same time providing a crisp vision, but it does not alter the accommodation and binocular vision function. ⁽⁵⁾ However, attention should be made while measuring fitting height so that the child only sees through the clear central zone.

Disclosure:

The blog is written solely for educational purposes, and it does not have any financial support and conflict of interest from the Hoya, Essilor, Zeiss, or CooperVision Company.

 

References

Baird, Paul N., Seang-Mei Saw, Carla Lanca, Jeremy A. Guggenheim, Earl L. Smith III, Xiangtian Zhou, Kyoko-Ohno Matsui et al. “Myopia.” Nature Reviews Disease Primers 6, no. 1 (2020): 1-20.

Pan, C. W., Ramamurthy, D., & Saw, S. M. (2012). Worldwide prevalence and risk factors for myopia. Ophthalmic and Physiological Optics, 32⁽¹⁾, 3-16.

Smith, M. J., & Walline, J. J. (2015). Controlling myopia progression in children and adolescents. Adolescent health, medicine, and therapeutics, 6, 133.

Berntsen, D. A., Barr, C. D., Mutti, D. O., & Zadnik, K. (2013). Peripheral defocus and myopia progression in myopic children randomly assigned to wear single vision and progressive addition lenses. Investigative ophthalmology & visual science, 54⁽⁸⁾, 5761-5770.

Lam, C. S. Y., Tang, W. C., Tse, D. Y. Y., Lee, R. P. K., Chun, R. K. M., Hasegawa, K., … & To, C. H. (2020). Defocus Incorporated Multiple Segments (DIMS) spectacle lenses slow myopia progression: a 2-year randomised clinical trial. British Journal of Ophthalmology, 104⁽³⁾, 363-368.

Gwiazda JE, Hyman L, Norton TT, et al. Accommodation and related risk factors associated wth myopia progression and their interaction with treatment in COMET children. Invest Ophthalmol Vis Sci.2004; 45:2143–2151.