Myopia Profile

Clinical

Understanding the NaturalVue multifocal contact lens

Posted on April 10th 2021 by Kate Gifford

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In this article:

The NaturalVue Multifocal contact lens by Visioneering Technologies is a daily disposable for myopia control - learn more here.

Originally published: April 10, 2021
Updated: December 13, 2022

The NaturalVue multifocal contact lens is a daily disposable designed for presbyopia and myopia control. The centre-distance design with a 'single high add' is purported to cover add requirements up to +3.00. With a unique design, the below is an exploration of the research on NaturalVue's optical design and myopia control efficacy.

The optics of NaturalVue

A typical centre-distance multifocal contact lens will have an 'optic zone' of central spherical power, representing the back vertex power of the contact lens. The back vertex power is usually chosen to match the best vision sphere of a spectacle refraction, after accounting for any vertex distance correction. The NaturalVue contact lens, however, features a continuous change in power 'almost immediately from the lens centre' as indicated in a 2020 ARVO abstract.1

This research, undertaken at the University of Houston, Texas, compared power profiles of the CooperVision Biofinity and Proclear centre distance +2.50 Add multifocals with the NaturalVue. The two CooperVision lenses were found to have a central optic zone of 1.5mm radius and then an increase in plus power of around 1.25-1.5D from the 1.5mm to 2mm radius. This 'add' power was then 'maintained out to a radius of about 3.8 mm for lower minus lenses and decreased for the most minus power lenses until reaching the edge of the optic zone.' By comparison, the NaturalVue multifocal CL 'started increasing in plus power almost immediately from the lens center until reaching maximum measured mean plus power of 3.31 ± 0.36 D at a radius of 2.6 mm. From a radius of 2.6 mm to 3.0 mm, there was a mean decrease in plus power of 4.11 ± 0.20 D. The power was then generally maintained from a radius of 3 mm out to the optic zone.'1

While this is a peer-reviewed abstract so not yet available in full paper form, this description of the NaturalVue power profile is in alignment with that graphically indicated by VTI, which represents the power profile to a 2.5mm radius. The blue line in the plot below shows the radial / sagittal / axial power profile (interchangeable terms) in agreement with the University of Houston abstract.

The red line shows the instantaneous / tangential power profile. You may be familiar with this concept if you fit orthokeratology lenses - both methods of topography description, or in this case a power profile, are useful but provide different information.

In 2019, VTI undertook and released work utilizing the NIMO wavefront sensor to represent the instantaneous power profile of the lens, as distinct from the radial / sagittal power profiles typically reported. This is represented in the graphic below, which is an excerpt from the NaturalVue Multifocal Power Profile PDF, from vtivision.com.

VTI-power-profile.png

To read more about instantaneous versus radial power profiling from VTI, click this link. It describes more about how instantaneous versus radial / saggital power profiling is useful for different multifocal lens designs. The sum total? The NaturalVue lens is described as a unique design with no spherical regions within the power profile. From the website:

The progression of plus power in NaturalVue® Multifocal contact lenses is significant enough to induce peripheral blur. This generates the virtual pinhole aperture to create an Extended Depth of Focus.


Learn more about the concept of 'extended depth of focus' in multifocal contact lens design and VTI's newly introduced concept of catenary-curve optics in our article What Does Extended Depth Of Focus Mean In Contact Lens Designs?


How does the NaturalVue work?

The absence of a spherical central optic zone in the NaturalVue lens is designed to create peripheral blur and a 'virtual pinhole aperture'. This explains the 'single add' suitability for presbyopia.  With regards to myopia control, this adheres to the peripheral defocus theory, whereby the peripheral retina receives myopic defocus as a slow-down or stop signal for eye growth. This has been shown extensively in animal models - Earl Smith III is arguably the world's leading researcher in this area and you can read a summary lecture of his here.

Optical quality outcomes

Another 2020 ARVO Abstract found that modelling of retinal image quality "through the NaturalVue and Biofinity CD lenses were comparable for all viewing distances." By comparison, "The central clear portion of DIMS spectacle lenses results in better image quality compared to the soft contact lens options evaluated. However, the peripheral portion substantially degraded image quality for all viewing distances."2

This means that despite the complex optics and absence of a spherical central optic zone in the NaturalVue, as for typical multifocal contact lenses, the optical quality and acuity should be similar. It's also worth noting that since a contact lens moves with the eye, there will be no difference in 'central' or 'peripheral' viewing experiences as for a myopia controlling spectacle lens.

Astigmatism 'masking' or 'correcting'?

The NaturalVue multifocal lens can also be used for presbyopia, in which case the NaturalVue fitting guide advocates selecting patients with no more than 1D of astigmatism. The more extensively detailed Professional Fitting and Information Guide, though, states that "The [multifocal] lenses may be worn by persons who exhibit astigmatism of 2.00 diopters or less that does not interfere with visual acuity."

This potential for correcting higher levels of astigmatism than is typical in spherical multifocal CLs is likely due to the unique optics of the NaturalVue lens, where the 'extended depth of focus' design is explained to create a 'virtual pinhole aperture'. Hence it is likely 'partially correcting' rather than 'masking' astigmatism. 'Masking' is a commonly used term for residual astigmatism in spherical contact lens corrections, although it has been repeatedly shown not to be effective. Read more about this in the Clinical Case The NaturalVue Multifocal Contact Lens – Astigmatism ‘Masking’ Or ‘Correcting’?

Myopia control and NaturalVue

The absence of a spherical central optic zone in the NaturalVue lens is designed to create peripheral blur and a 'virtual pinhole aperture'. This explains the 'single add' suitability for presbyopia.  With regards to myopia control, the presumed mechanism adheres to the peripheral defocus theory, whereby the peripheral retina receives myopic defocus as a slow-down or stop signal for eye growth. This has been shown in animal models - Earl Smith III is arguably the world's leading researcher in this area and you can read a summary lecture of his here.

Animal studies

Two studies on the NaturalVue lens design were undertaken on chickens at the University of Waterloo as proof of concept. The first compared two lens designs to determine the most effective peripheral add gradient.3 The second study showed that lens-induced myopia in chicks could be slowed in axial progression and halted or even reversed in refractive progression with the two test lens designs.4

Human studies - retrospective case series data

In 2018, Cooper et al5 published a retrospective case series analysis on 32 myopic patients across 10 practices, with patients completing between 6-25 months of lens wear with a mean of 11 months. The children progressed -0.90D+0.57D in the year before initiating lens wear, which reduced to -0.03D+0.17D per year of annualized progression when wearing the NaturalVue. Only one child of the 32 continued to increase in their myopia progression. This pilot study did not include measures of axial length.

Also in 2018, Aller presented an ARVO abstract6 of retrospective data from his single practice. Twenty-six consecutive patients with a mean age of 11.8 years (range 6-22 years) were switched from a variety of corrections (including single vision, orthokeratology, atropine and other multifocal contact lenses) into NaturalVue. Myopia progression prior to fitting NaturalVue, and once wearing the new lens, were calculated. Progression before NaturalVue was 'adjusted to a six month rate' of  -0.45+0.42D, and after fitting to a mean of 0.00+0.30D.

Eleven of these children had axial length data available pre- and post-NaturalVue fitting, which showed a reduction from a mean 0.13+0.08mm progression to 0.07+0.07mm. The authors report that this statistically significant reduction was found even when looking at the group of children who were undergoing previous myopia treatment.

Aller, Cooper and co-authors presented another retrospective study abstract at the 2019 BCLA meeting. This dataset included 141 children who exhibited at least -0.50D change in the year before commencing treatment and a mean progression of -1.07+0.83D.7 The authors reported an 'approximately 1.00D reduction in RE change compared to baseline at all timepoints' which was a statistically significant change to the baseline. Axial length growth of the children before treatment was between 0.03-1.03mm, with a mean of 0.42+0.33mm. This reduced to an average change of 0.19+0.17mm at the 12-17 month mark, which was reported as a 55% reduction in progression.

At the 2020 Global Myopia Symposium, Visioneering Technologies presented additional clinical data showing myopia control over a longer time period. This was reported on in a sponsored article on Review of Myopia Management; New clinical evidence through five years: NaturalVue Multifocal. It continues on from the retrospective 2018 study by Cooper et al. and this time included 153 children followed from between 6 to 59 months across multiple locations. They reported a 0.90D decrease in refractive progression when compared to the children’s historical progression before commencing treatment. Thirty-six of these children had their axial length measured, and had an average change of 0.10mm per year. This cohort is continuing to be tracked, so future data can be expected.

NV-graph.png


Figure 2 from Cooper et al 20185  with the following caption:
'Individual data plots of baseline refractive error (spherical equivalent [SE] in diopters) versus follow-up time (months), both before and after wearing NaturalVue Multifocal for 6 to 25 months (right eye). The change in the y-axis indicates the change in refraction, the change in the x-axis indicates the number of months that each treatment was followed, and the gradient of each line indicates the amount of myopic progression both before and after treatment.'


In July 2022 a new analysis of retrospective data was published, providing more detailed information on clinical experiences of 196 patients aged 5 to 20 years who had worn NaturalVue Multifocal lenses for between 6 and 72 months. The average annual refractive myopia progression of the wearer group at each time point was less than 0.25D. Read more about this data in our Myopia Profile Science Summary.


What we know

NaturalVue appears to have a myopia control effect. The retrospective data presented thus far indicates real-world clinical observations, and if the individual patient and their parent observe a slowing of refractive and axial myopic progression, this is a good outcome for that individual.

What we don't know

What NaturalVue's comparative myopia control effect is to other products available, or to a single vision wearing control group. None of these studies include control groups, so the absolute reduction in dioptric or axial progression is not yet known. The percentage rates of control presented thus far are a comparison to pre- and post-fitting in the same individuals, rather than comparing between two matched control and treatment groups. Since myopia progression tends to slow with time anyway,8 comparing progression before and after an intervention in the same individuals will likely always show some percentage of slowing, brought about by increasing age.

Where does NaturalVue fit in your myopia control toolkit?

The three clinical advantages of the NaturalVue multifocal contact lens are being a daily disposable, available in powers up to -12.25D, and potentially able to 'partially correct' up to 2D of astigmatism (provided good acuity is achieved).

A daily disposable is the safest modality of myopia controlling contact lenses. Read more about Contact Lens Safety in Kids via the link.

While informed consent is an important component of any myopia control strategy, it's important to note that managing high myopia (more than 5-6D) does bring its own particular challenges due to lack of research evidence on myopia control efficacy in general, as well as the importance of ocular pathology risk management. Contact lenses are an important part of vision correction for high ametropia, though, hence it's beneficial that the NaturalVue lens offers an option for myopia correction and a potential for myopia control for high and very high myopes.


Further reading

Clinical case studies on NaturalVue


Meet the Authors:

About Kate Gifford

Dr Kate Gifford is a clinical optometrist, researcher, peer educator and professional leader from Brisbane, Australia, and a co-founder of Myopia Profile.

About Cassandra Haines

Cassandra Haines is a clinical optometrist, researcher and writer with a background in policy and advocacy from Adelaide, Australia. She has a keen interest in children's vision and myopia control.


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

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