Navigating astigmatism for the young myope - Q&A with Joy Hynes, Carla Schneider and Elaine Lucas

I find that the significance of astigmatism for a patient’s vision can vary depending on their level of myopia. For a patient with low myopia (e.g. a prescription around -1.00DS), even a moderate amount of astigmatism (over -1.00DC) can be significant and affect their vision. However, for a patient with high myopia (e.g., a prescription around -8.00DS), a higher degree of astigmatism (up to -2.00DC) might not have as much of an additional impact on their vision since their overall refractive error is already very high.  

In our practice, we find that fewer than 20% of myopic patients (or approximately 1 in 5) have astigmatism that significantly impacts their vision and requires special attention. Holden et al (1975) found that 55% of the population had less than 0.75D of astigmatism, 39% had 0.75DC or higher and about 6% had more than 2.50D.¹ If we consider 0.75D or more to be ‘significant’ astigmatism, you’d expect toric soft contact lenses to be required in about 45% of patients.¹ If considering 1.00D or more as ‘significant,’ than it’d be around 25% of the population:¹ I’ve found this to closely align with my experience in practice, but each individual patient has different visual needs so it's essential to tailor contact lens prescriptions to each person's unique requirements to achieve optimal visual correction and comfort.

The impact of significant astigmatism on visual acuity and quality of life can be substantial.² Because of this, it's crucial to have effective tools and strategies in place to manage astigmatism in myopic patients. There aren’t many soft contact lenses for myopia control that also correct astigmatism, so having at least one option for that is crucial: I use the NaturalVue multifocal soft contact lenses as my go-to daily disposable when encountering a myopic astigmat. 

Certainly, astigmatism is present in many of my myopic patients – those with high myopia³ and low myopia. Astigmatism can be concerning as it may complicate the management of myopia, often necessitating more intricate treatment approaches for effective control.  This is because astigmatism adds another layer of visual distortion, which can affect the overall clarity of vision and the effectiveness of standard myopia treatments. Particularly when there is a motivation to wear contact lenses and astigmatism is present, then options can be limited as other factors need to be considered such as comfort of the lens and the patient’s preferred wearing schedule. 

Masking astigmatism involves minimizing or hiding the effects of astigmatism without directly correcting the underlying refractive error through the use of a spherical soft contact lenses. When we use a typical spherical lens and add on half the cylinder power, we are masking the astigmatism as opposed to prescribing for it. This approach is often used when prescribing spherical lenses for myopia control. The spherical lens, in combination with the tear film, helps to reduce the visual distortion caused by astigmatism, but it does not directly correct the underlying issue. 

 Correcting astigmatism, on the other hand, involves directly addressing the cylindrical component of the refractive error by using toric lenses or other optical corrections. Research indicates that using toric soft contact lenses to correct astigmatism provides patients with better visual acuity,^4,5 with improvements of at least a half-line or more compared to wearing spherical soft contact lenses.^6,7 The optics of the NaturalVue Multifocal lens means we are not masking the astigmatism, we are in some way correcting it. The high plus add power of the NaturalVue Multifocal lens is suppressed by the visual cortex and has a “virtual pinhole effect.”  This ends up lessening the effect of the astigmatic blur and other aberrations as seen when we use an actual pinhole with our patients. 

Astigmatism affects the management of a young myopic patient in several important ways. Some important considerations to keep in mind are:

• Type of contact lenses: For young myopic patients with astigmatism, selecting the appropriate type of contact lenses is critical. While spherical lenses may mask some astigmatic effects, toric lenses specifically designed for astigmatism provide better correction.⁶ Historically astigmatic patients were fitted with Biofinity Toric Centre-Distance lenses for myopia management. Since having NaturalVue in our portfolio, we have had great success with fitting astigmatic patients with this lens instead. This is now our go–to lens of choice. 
• Daily disposables: For children, daily disposable contact lenses are often preferred due to their convenience, hygiene, and comfort. Children report higher comfort levels with daily disposables, like NaturalVue, compared to monthly toric lenses. This comfort can lead to better compliance and a more positive experience with contact lens wear, which is crucial for successful myopia management.
• Visual functioning: Uncorrected astigmatism can lead to blurred vision, eye strain, and headaches,^5,7 which can affect a child’s ability to perform well in school and other activities. By accurately correcting astigmatism, we support the child’s overall visual health and development.

My experience with the NaturalVue Multifocal soft contact lens for young myopic patients has been overwhelmingly positive, especially in addressing myopia control in patients with astigmatism. These lenses offer multiple benefits, making them a preferred choice in my practice. Firstly, the NaturalVue Multifocal soft contact lens streamlines the management process for both the patients and their families. The ease of use and the all-in-one solution these lenses provide enhance compliance among young patients. With other soft contact lenses for myopia control, a separate pair of spectacles to correct any residual astigmatism may be required to wear over the contact lenses. Since the NaturalVue Multifocal soft contact lenses can correct astigmatism, this alleviates that burden making myopia control easier and even financially more sustainable. This is particularly beneficial for families managing high myopia, where the costs can quickly add up.

One particular case that stands out is a 16-year-old patient with high myopia and -1.50D of astigmatism in each eye. Since fitting her with NaturalVue Multifocal soft contact lenses in 2021, she has been able to comfortably achieve a visual acuity of 6/6 in each eye. Remarkably, her prescription has remained stable since then. This stability is a testament to the effectiveness of NaturalVue Multifocal soft contact lenses in managing her myopia progression and correcting her astigmatism simultaneously. Furthermore, the comfort and convenience of NaturalVue Multifocal soft contact lenses mean that this patient no longer needs additional glasses for over-contact lens wear. This has been a significant relief for her parents, who no longer have to constantly remind her to wear her glasses. The patient herself is much happier and more confident, as she can rely on soft contact lenses for all her visual needs.

Overall, the NaturalVue Multifocal soft contact lenses have transformed how we manage young myopic patients with astigmatism in our practice. They provide excellent visual outcomes, ease of use, and financial benefits, making them an invaluable tool for myopia control and astigmatism correction.

Yes, I have found excellent results. The NaturalVue Multifocal daily soft lens has become my go-to option for children who have more than 0.50D of astigmatism. These lenses are particularly effective as I have found that they provide better corrected visual acuity compared to traditional spherical lenses. For children under the age of eight, achieving the best possible visual acuity is crucial, as this is a critical period for visual development.⁸ Poorly corrected astigmatism at this age can lead to amblyopia.⁹ By using NaturalVue lenses, I can ensure that these young patients receive the sharpest vision correction possible, thereby reducing the risk of amblyopia.