Toric Contact Lens Prescribing Considerations and Differences in Lens Design

Astigmatic patients can sometimes be challenging to successfully fit in contact lenses. There are a variety of factors that can impact the success of a toric contact lens fitting that might include:

Interaction of eyelids with the lens
Lens rotational stability
Lens shifting during rapid head movements

All of these factors can impact visual outcomes and should be considered when it comes to toric contact lens prescribing. For this reason, many practitioners might perceive toric prescribing as a bit more cumbersome which could lead to particular behaviors such as avoidance in prescribing toric lenses, or an eagerness to keep patients in a lens that might be underperforming.

For example, I have encountered many astigmats in my practice who were either told contact lenses were not a good option for them or were prescribed a spherical lens based on a spherical equivalent calculation, rather than a toric contact lens. I have also encountered many astigmatic patients who wear spherical lenses because they tried a certain toric lens that did not provide them with acceptable vision or comfort and were not given any additional options.

These are actually my favorite contact lens patients because it gives me the opportunity to provide them with a new or better contact lens wearing experience, which typically results in a very happy patient and is an incredible practice builder.

Learn more on why identifying and understanding patient need is so critical to the success of your practice.

Why Should You Always Fully Correct Astigmatic Patients?

All too often, I encounter patients in my practice with low cylinder that has attempted to be masked by a spherical lens. I discover that while at times it is a matter of economics, more often it is because these patients simply were not presented with a toric lens as an option.

This leads me to ask, “Why? Does a minimal amount of cylinder really not make that much of a difference in terms of vision or visual performance?” Actually, it does.

Prescribing contact lenses should be no different than prescribing glasses. Just as you would fully prescribe cylindrical correction in spectacles (of course there are always exceptions), it is equally as important to fully correct astigmatism in contact lenses, even for these patients with low cylinder. If a patient has a prescription of -1.75-0.75×180, I would imagine most practitioners would not think twice about prescribing -1.75-0.75×180 in spectacles. So why then would anyone prescribe -2.00DS in contact lenses?

As we know, uncorrected astigmatism results in reduced visual acuity, which can make a significant difference in visual comfort.1 The Snellen chart below shows the difference in visual acuity between a fully corrected patient, and a patient with uncorrected cylinder; the cylinder may be slight, but it can make a world of difference for patients. After moving these spherical-lens-wearing patients to toric lenses in my practice, the response is always the same: “It’s like going from standard definition to high definition.” Who doesn’t want to see the world in high definition?

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Reduced visual acuity can impact visual comfort especially when looking at digital screens,² which is particularly problematic in a world where we spend so much time consuming digital content.

Many of us encounter patients who complain of glare or challenges with nighttime driving. While there are certain ocular conditions that can contribute to these complaints, in a young, healthy patient, I often find myself looking carefully at refractive error. What I have found is that many of my spherical contact lens wearing astigmats with a small amount of uncorrected cylinder typically experience this issue.

These patients always seem to complain about vision when driving, especially at night. I use this as the perfect opportunity to demonstrate astigmatic correction by showing these patients 0.75D of cylindrical correction at the appropriate axis, and the response nearly every time is “Wow, that is so much clearer!”

By fully correcting astigmatism, we can help improve the visual quality of life in patients,³ as well as enhance driving performance.⁴ I have found that these patients convert into a toric lens almost every single time after experiencing the increased visual clarity and performance a toric lens can offer them.

Benefits of Prescribing Toric Lenses

Other than providing the best possible vision for patients, which is one of our primary goals as eyecare providers, prescribing toric lenses is also good for your practice. The increase in patient satisfaction can go a long way towards driving word of mouth referrals from happy patients. Studies show that when astigmatic patients are made aware of benefits, a majority of them prefer to purchase soft toric lenses over spherical lenses5 which can generate more revenue for your practice.

Results from a study of 60 habitual soft contact lens wearers with prescription range of +4.00 to -9.00DS, -0.75 to -1.75DC, axis range 0-180 degrees showed that:5

3.5X more patients preferred toric lenses versus spherical lenses (78% to 22%)
96% of astigmats were willing to pay 10% more for the toric lens
90% of low astigmats (cyl: -0.75DC) indicated a similar willingness to pay

In my practice, I have found that by making astigmatic patients aware of the potential improvement in vision and visual comfort toric lenses can offer, cost becomes truly a secondary discussion and hardly ever a barrier to acceptance. The most important factor is that you give these patients a choice.

Choosing a Toric Contact Lens

Not all toric lenses are designed the same, and as a result, not all toric lenses perform the same for patients. I hear it all the time in practice:

“I’ve worn those contacts for astigmatism and I just couldn’t see out of them,” or, “Those contacts for astigmatism aren’t comfortable.”

These are patients where we need to dig a little deeper and ask about what lenses they are wearing or have tried wearing in the past.

There are several current toric contact lens designs used by manufacturers:

Prism Ballast – these lenses have a thin apex and thick base
Peri-Ballast – these lenses have peripheral ramp angles and a thick inferior ballast
BLINK STABILIZED® Design Lenses – these lenses have a unique design that works with the natural blink of the eyelid

Prism and Peri-Ballasted Lenses:

These lenses are gravity dependent and can be challenged by eye and head movements outside central or straight-ahead viewing. This means that patients who are playing sports which require fast eye movements or who tilt their head while watching tv or even patients with a particular way of blinking, can cause interference with the lens position on the eye. This may, in turn, cause visual disturbances. In a clinical study, prism and peri-ballasted lenses, such as Purevision Toric, Proclear Toric and Air Optix for Astigmatism, were shown to rotate about 2.5 times more than ACUVUE® OASYS for ASTIGMATISM, a BLINK STABILIZED® Design.⁶

Think about how often you hear from your toric contact lens wearing patients, “My vision gets blurry when I blink and then takes a while to get clear.” It is a complaint I encounter often, and often deters patients from wearing toric contact lenses as this experience creates a lot of doubt.

Rotational stability can be such an important factor in visual outcome, so choosing a lens that can provide stability for your astigmatic patients who lead active lives can impact wearing success and acceptance.

Another major factor to consider is induction of vertical prism. When fitting a patient in spectacles, we pay careful attention to measurements because we know that lens induced prism can lead to symptoms of asthenopia, headache, and visual discomfort.⁸

When fitting contact lenses, we need to consider this factor as well. Contact lenses that rely on prism or peri-ballast design, can induce or create prism within the optic zone. A study measuring the mean vertical prism in the central 6.0mm zone of eight commercially available soft toric lenses showed that lenses with prism or peri-ballast designs had mean vertical prism ranging from 0.5∆ to 1.2∆ unlike those lenses with BLINK STABILIZED® Design.⁷

Vertical heterophoria possibly caused by prism dissociation due to the presence of induced optical prism is a relevant factor for practitioners to consider when fitting toric contact lenses for monocular astigmats or those requiring a mix of toric soft contact lens designs. Clinical studies have not been done to fully characterize the clinical effects of differences in base down prism among different contact lenses.

So what makes BLINK STABILIZED® Design different?

BLINK STABILIZED® Design is a proprietary toric design from ACUVUE ®. The design of the lens works to mitigate the factors which can impact of the success of contact lens wear in our astigmats.

BLINK STABILIZED® Design is present in all ACUVUE® Brand Contact Lenses for ASTIGMATISM including: 1-DAY ACUVUE® MOIST Brand Contact Lenses for ASTIGMATISM, ACUVUE® OASYS Brand Contact Lenses for ASTIGMATISM, ACUVUE® VITA® for ASTIGMATISM and ACUVUE® OASYS 1-Day with HydraLuxe™ Technology for ASTIGMATISM.

Read more about BLINK STABILIZED® Design.

Every ACUVUE® contact lens is inspired by and works with the natural eye. BLINK STABILIZED® Design in ACUVUE® toric lenses works naturally with the eyelids and was designed to realign instinctively with every blink. The lenses quickly orientate and stabilize9 to help provide clear and stable vision throughout the day even with extensive eye and head movements.¹⁰

The comparison below shows the impact of head position on the rotation of toric contact lenses on the eye.

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ACUVUE® BLINK STABILIZED® Design:¹¹

Facilitates lens settling in just three minutes
Helps ensure stabilization during blinking and is resistant to eye/head movements
Is present in all ACUVUE® Brand Lenses for ASTIGMATISM – giving clinicians a wide range of parameters, modalities, and materials to meet the needs and lifestyle of many of our patients

You can check out all of the contact lens and consumer eye health products available from Johnson & Johnson Vision in this article and infographic.

Discussing Toric Lenses

Great opportunity can exist in educating astigmatic patients on toric lenses and prescribing them with confidence. You may be surprised by how much you can improve the vision in your spherical wearing astigmats and they will be extremely thankful to you for fully correcting their vision. When encountering these patients, it is important to ask questions, even if they think they are happy or currently satisfied with their lenses.

Ask these patients what lenses they have worn, current issues or challenges with their lenses and their visual comfort throughout their daily activities. From there, make prescribing decisions on how to improve their contact lens wearing experience and increase patient satisfaction, all of which can help grow your practice.

Prescribing contact lenses is both an art and science. Understanding how designs work and how they differ, like as in the case with BLINK STABILIZED® Design, can make a major difference in the type of contact lens wearing experience you provide your patients.

References:

Sulley A, Young G, Lorenz KO & Hunt C. Clinical evaluation of fitting toric soft contact lenses to current non-users. Opthalmic Physiol Opt 2013, 33, 94-103.
Rosenfield M et al. The effects of induced oblique astigmatism on symptoms and reading performance while viewing a computer screen. Opthal Physiol Opt. 2012; 32(2): 142-8.
Cox SM et al. Efficacy of Toric Contact Lenses in Fitting and Patient-Reported Outcomes in Contact Lens Wearers. Eye & Contact Lens 2017 In Press.
Cox D, Banton T et al. Does correcting astigmatism with toric lenses improve driving performance? Optom Vis Sci. 2015 Apr, 92(4):404-11.
JJVCI data on file 2015, Biliateral, subject masked, randomized, cross-over study, 1 week DD wear with 1-DAY ACUVUE® MOIST for ASTIGMATISM and 1-DAY ACUVUE® MOIST.
McIlraith R, Young G, Hunt C. Toric lens orientation and visual acuity in non-standard conditions. CLAE 2010; 33 (1): 23-26.
Sulley A, Hawke R, Lorenz KO, et al. Resultant vertical prism in toric soft contact lenses. Cont Lens Anterior Eye 2015;38(4):253-7.
Moodley VR, Kadwa F, Nxumalo B, Penceliah S, Ramkalam B, Zama A. Induced prismatic effects due to poorly fitting spectacle frames. S Afr Optom 2011, Nov. 70(4) 168-174.
JJV data on file, 2017. ACUVUE® Brand Contact Lenses for Astigmatism overall fitting success, orientation position, rotational stability & vision performance.
Chamberlain P, Morgan PB, Moody KJ, Maldonado-Codina C. Fluctuation in visual acuity during soft toric contact lens wear. Optom Vis Sci 2011 Apr 1; 88(4)E534-8.
Hamada, Weslie M., OD, FAAO. “Find Efficiencies in Toric Prescribing.” ACUVUE® Brand Contact Lenses for ASTIGMATISM. Johnson & Johnson Vision Care, Inc, 2016. Web. 11 Nov. 2016.

Important Safety Information:

ACUVUE® Brand Contact Lenses are indicated for vision correction. As with any contact lens, eye problems, including corneal ulcers, can develop. Some wearers may experience mild irritation, itching or discomfort. Lenses should not be prescribed if patients have any eye infection, or experience eye discomfort, excessive tearing, vision changes, redness or other eye problems. Consult the package insert for complete information. Complete information is also available from Johnson & Johnson Vision Care, Inc., by calling 1-800-843-2020 or by visiting acuvueprofessional.com.

ACUVUE®, ACUVUE® OASYS, 1-DAY ACUVUE® MOIST, and BLINK STABILIZED® are trademarks of Johnson & Johnson Vision Care, Inc.