The second part in a series, this article discusses the opportunities in toric lens fitting and care; “Click here to read part 1.”
CONFIDENT AND PROACTIVE TORIC LENS RECOMMENDATION
The wide variation in soft toric fitting practices around the world, coupled with a sense that some ECPs are not fully confident in the ease of fitting and overall performance of soft torics provides a number of areas to address. Discussed below and summarised in Table 1, these relate to broad areas such as patient needs, professional communication, product performance, and practice set up. Addressing these concerns should help support ECPs who do not already embrace soft toric options to feel more confident in recommending them more frequently.
The importance of correcting low levels of astigmatism
Low to moderate levels of astigmatism are rarely omitted from spectacle corrections. Leaving 1.00DC of astigmatism uncorrected can result in a significant decrease in distance and near visual acuity,20 reading speed,20 decrease reading fluency,21 and stereoacuity.22 Symptoms of ocular discomfort, dry eye and headaches can also result from uncorrected astigmatism.20,21 A once popularly held view that thick or high modulus spherical designs can ‘mask’ astigmatism has proved not to be true.23-26 Likewise, aspheric lenses do not demonstrate improved visual outcomes for low astigmats compared to toric corrections.27,28
Poor satisfaction with vision in contact lenses is clearly undesirable and can ultimately lead to drop out. Sub-optimal vision performance is a significant cause of contact lens drop out by itself.29,30 Astigmats have been shown to over-index in contact lens drop outs,29,31,32 a fact which serves as a pertinent reminder to ensure the vision and comfort needs of this patient group are fully met in contact lenses.
The link between comfort and vision in soft toric lens wear35
It is worth highlighting the results from this recent study. Maldonado-Codina and colleagues investigated the association between comfort and vision in soft toric lens wearers. Across three different daily disposable soft toric designs, subjective vision quality scores were associated with comfort scores. This means that greater comfort scores occurred with great vision quality. The authors note how these results suggest that perceived suboptimal vision quality can impact lens comfort. A result which highlights the important role of the ECP to ensure vision is fully corrected to the patients satisfaction in order to help maximise their overall perception of comfort and lens performance.35
The evidence summarised above shows that, when compared with spherical lenses, correction of astigmats with toric lens designs results in significantly improved subjective and objective visual performance.36,37 This can be demonstrated to a patient in practice by having them view the smallest line of letters they can see both with and without the cylinder correction in place. These differences can be subtle and are often better demonstrated using a real-world target. The benefit could be demonstrated via viewing small detail on digital devices, or with night driving for instance. If an extended trial is not practical or desired, ensuring examples of real-world visual tasks are available to view in practice is a good alternative.
Patient expectations
Sub-optimal vision or comfort can result in drop out from lens wear. For new wearers, a prospective study established the drop out at twelve months to be 22.4%, with poor vision being cited as the main cause of discontinuation (41%) followed by comfort (36%).32 This highlights once again the importance of ensuring a patient is happy with the vision in their contact lenses.
Recent insights have generated a better picture of the expectations that patients place on their ECP too. Health and vision are both in the minds of patients when considering what they want to hear from their ECP. A separate survey of more than 5,000 lens wearers in five countries established that 86% agree they expect their ECP to make a recommendation for the soft contact lenses that provide the best possible vision correction for their eyes, regardless of cost.39 The fact that patients expect to hear about their best options regardless of cost is noteworthy. This information should help overcome any barrier in the ECP’s mind about price. The message from the patient is clear: “tell me about the best options to help me make an informed choice.”
Product performance and practice set up
The performance of early hydrogel soft toric designs include reports of intolerance, inadequate fit, handling difficulties and problems with vision.40 Unpredictable fitting characteristics,41 and variable lens position with blinking,42 and head position,2,3 all contribute to fluctuating vision and poor outcomes. Given this history, it is understandable, as seen in the survey of US practitioners, that some ECPs may still hold concerns about the performance of soft toric lenses.8 However, the design of modern toric lenses has evolved over time, with currently available options designed to achieve both quick and consistent fitting for the ECP, along with delivering comfort and stable vision for the wearer. A number of different approaches to achieving reliable and predictable orientation position and rotational stability exist such as (Optimised Toric Lens Geometry™), CooperVision.
Several studies have examined the performance of these designs for static high contrast acuity, real-world visual tasks, rotational stability with eye and head movements, and rotational recovery, generally reporting, with some small differences between designs, that modern methods of stabilisation perform well.2-7 In fact, a recent analysis of over four hundred subjects from ten clinical trials using one proprietary design established across a number of factors, that a successful lens experience was achieved in all categories 83% of the time.43 Those factors included orientation success, fit acceptance, visual acuity, visual quality and comfort, and each individually returned success over 90% of the time.43
Successful fitting of astigmats in three different groups has been demonstrated: existing soft spherical lens wearers, contact lens drop outs and neophytes.44 In order, the fit success rate for those three groups was 80%, 75% and 70%, with previous spherical lens wearers also recording an improvement in visual acuity, and the neophyte group a level of vision in their contacts lenses comparable to their spectacles. Results such as this should help build confidence in the visual performance of soft torics compared to spectacles.
Limited prescription availability is a barrier sometime cited by ECPs. It is of interest to note ECPs tend to underestimate the proportion of patients that can be corrected with available soft toric contact lenses. When asked in a recent survey, ECPs felt one single reusable soft toric on average could be prescribed to between 55-74% of their patients depending on the product.8 When modern soft toric lens availability was compared to a large database of spectacle prescriptions it was actually shown that typical coverage is higher than ECPs believe. An example of this is a toric lens with cylinder correction available up to -1.75DC, spherical powers from +4.00D to -8.00D and 10 degree axes available around the clock actually provides cover for at least 90% of spectacle prescriptions,45 and this would be even higher for some soft toric lenses that have additional parameters available.
The length of time required to achieve a successful soft toric fit has been voiced as a concern in the past. Modern soft toric lenses are actually as quick to fit as spherical lenses,1 the fitting of which can be further supported by manufacturer supplied fitting sets and online fitting calculators. Both of these enable time-efficient fitting for ECPs and patients.
Initial lens selection, either from the trial set or via pre-ordering, can be supported in a number of ways. This may be via printed manufacturer fit guides and tools which confirm available prescription range, through to online toric lens calculators available, for example, OptiExpert™ from CooperVision, OptiExpert™, has been shown to agree with investigator prescribed final prescriptions in 9 out of 10 eyes for different toric lenses.46,47 Use of OptiExpert™ support accurate initial trial lens selection for the brand of toric lenses in question, and also enables trained support staff to order trial lenses in ahead of scheduled-appointments if required. Both the accuracy of initial prescription choice, and the ability to use staff to order ahead, are helpful to ensure efficient use of time in practice. These approaches can be applied to other lens fittings, including spherical and multifocal.
Where might other opportunities to build upon toric success exist? Click here for Part 3 in this series, Additional Opportunities.
References:
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