The GP market has surprisingly continued to grow over the past few years. In the United States, a total of 14% of contact lens fits and refits were into some form of rigid lens.¹ This is compared to 13% for 2016² and 9% in 2014.³ Internationally, GPs accounted for 12% of fits, which also represents an increase over the previous year.⁴

The GP market appears to be benefitting especially from advances in scleral lens designs and applications, the increasing interest in myopia control in general, and ongoing improvements in multifocal and hybrid designs.

These advances were not necessarily reflected in the responses to the annual Contact Lens Spectrum GP Usage survey, the results of which are provided throughout this article. With a total of 168 respondents, the overwhelming primary GP application continues to be conventional corneal designs, followed by sclerals and then non-scleral lens designs for irregular corneas (Figure 1). As compared to the 2017 survey, the preference for both multifocal and toric designs has increased; sclerals, non-scleral designs for irregular corneas, and hybrids are approximately the same; and conventional corneal and corneal reshaping designs have decreased.⁵ It was encouraging that 95% of those responding to the survey fit GP lenses in their practice.

WORD ON THE STREET

The GP Lens Institute (GPLI) Advisory Board members, consisting of prominent specialty contact lens fitters, were surveyed as to what GP lenses meant to the growth of their practice. Representative responses are provided in the sidebar on page 25.

They were also surveyed as to what they believed was the most important new development in GP lenses in the last 12 months. The answers were very definitive and, in fact, almost exclusively pertained to either one (or both) of the following innovations: lens coatings and scleral lens innovations. As with the 2017 poll, the increasing use of a 90% water polyethylene glycol (PEG)-based coating for GP lenses was popular, with 10 respondents mentioning this innovation. Specifically, they spoke of its benefits for dry eye patients who have a tendency to induce surface filming as well as for scleral lens wearers and presbyopic GP wearers.

However, the most common important development pertained to scleral lens design innovations, with 15 respondents citing this as the primary factor. This includes the ability to better manufacture and modify peripheral curves and the increasing use of corneo-scleral topographers, both of which help improve haptic alignment to an asymmetric scleral surface.

SCLERAL LENSES

Scleral lenses continue to be an exciting and progressive area for GP lenses. Growth is ongoing as new designs, streamlined fitting methods, and the introduction of instrumentation to assess both corneal and scleral topography—as well as the quality of the fitting relationship—continue to be introduced and to grow in popularity. The results of our readership poll indicate that 79% of the respondents fit scleral lenses and that, of those individuals, approximately two-thirds have increased their scleral use in the past year, and less than 8% have decreased use of these lenses (Figure 2).

Research continues to help us understand scleral curvature and shape. Several recent studies reported that approximately two-thirds of eyes of prospective scleral lens patients did not exhibit a spherical or toric-regular scleral surface pattern but instead exhibited asymmetry.^6,7 Of those eyes, 40.7% had asymmetric depressions (or steep areas) or asymmetric elevations (or flat areas), and 26% had a recognizable toric pattern with elevations and depressions but did not have the customary 180º periodicity. Evidence shows that increasing use of corneo-scleral topography, often identifying the need for toric haptics, will increase patient success with scleral lenses.

One of the most important advantages of scleral lenses—in addition to being a primary corrective option for patients who have ocular surface disease—is comfort relative to their corneal GP counterparts. Visual acuity may improve in irregular cornea patients who were intolerant to corneal GP lenses and were refit successfully into scleral lenses.⁸ In addition, the scleral lenses could be worn for a longer time period compared to the corneal lenses. Scleral lenses are also becoming an increasingly important option after any corneal procedure that results in a fragile epithelium because they vault the cornea. In fact, in corneal cross-linking, scleral lens application is possible as soon as three weeks after the procedure.⁹

Progress is also being made with wavefront-guided scleral lenses. Researchers have found that wavefront optics lenses—versus traditional scleral lenses—resulted in improved logMAR visual acuity and reduced higher-order wavefront errors.¹⁰

The jury is still out with regard to scleral lens applications with healthy eyes (i.e., astigmatism and presbyopia). A large—and increasing—number of multifocal scleral designs are entering the market. In a recently published study pertaining to scleral lenses versus soft toric lenses for astigmatic patients, 75% of the subjects in this cross-over study preferred the vision of the scleral lenses.¹¹

The poll responses were also fairly diverse when it came to what respondents considered their “go-to” filling solution for scleral lenses; U.S. Food and Drug Administration (FDA)-approved sodium chloride-based solutions, sodium chloride inhalation solutions, and non-preserved tears/lubricants were all cited as being commonly used (Figure 3). However, with the knowledge that preservatives can be toxic to the eye if they are in contact for a prolonged period of time, it was surprising to note that almost 14% of respondents used a preserved wetting/conditioning solution as their recommended filling solution for scleral lenses.

ORTHOKERATOLOGY

Two thousand eighteen brought more uniformity to using the term “orthokeratology”—versus “overnight orthokeratology,” “corneal reshaping,” “corneal refractive therapy,” and “vision shaping treatment”—to describe the process in which specially designed GP lenses reshape the cornea and reduce myopia.

Each year, we learn more about how orthokeratology successfully reduces myopia, as well as axial growth, in young people. The industry then complements this knowledge with an ongoing introduction of improved lens designs. Six years ago, Walline reported that the goal for a clinically meaningful reduction in myopia progression is 50%.¹² If a child is a 1.00D myope at age 8 and progresses 0.50D per year, he will be a 5.00D myope at age 16. However, if he wore some form of myopia control device that reduced myopia by 50%, he would only be a 3.00D myope at age 16. We are close to achieving this goal with orthokeratology; reports show a reduction in myopia progression of between 41% to 45%.^13-15 Orthokeratology also has numerous benefits including the ability to allow young, active individuals to participate in athletic activities without any form of correction while, at the same time, reducing myopia progression.

Researchers have also found that the rate of microbial keratitis with orthokeratology lenses is no greater than with extended wear in general.¹⁶ In a recent study comparing 104 eyes of orthokeratology patients versus 78 eyes of soft lens wearers (all ≤ 16 years old at baseline) over a 10-year period, there was no significant difference in adverse events between the two groups and no reports of microbial keratitis.¹⁷ In addition, the myopic refractive error changed from –2.63D (on average) to close to plano within the first few months and stayed constant for the remainder of the 10-year period. Conversely, the soft-lens-wearing group changed from –2.85D (on average) at baseline to almost 5.00D at 10 years, with the great majority of the change occurring in the first five years. Of course, with the reversal effect that occurs when lens wear is discontinued, it is imperative for orthokeratology patients to purchase a backup pair in case something happens to their lenses.

Likewise, it is very important to be able to initially assess potential orthokeratology patients—as well as to assess them over time—via topography. This assists with determining the location of the corneal apex, the eccentricity, the amount of induced change over time, and where the change is occurring. And recently, the influence of paracentral corneal toricity (using elevation data on the treatment zone decentration) was evaluated to assist in determining when a toric orthokeratology lens would be indicated.¹⁸ Corneal topography and continuing advances in software specifically pertaining to orthokeratology have resulted in greater ease of fitting, as empirical success rivals that of diagnostic fitting.¹⁹

Estimates indicate that there are between 500,000 and 1 million orthokeratology wearers in the United States²⁰ and as many as 1.5 million in China.²¹ Our Contact Lens Spectrum survey indicates that overall, more respondents have increased their orthokeratology use in the last year compared to those who have not (Figure 4). However, when asked what their myopia control program includes, soft multifocals continued their trend from previous years and were used much more than orthokeratology (54% versus 34%) was for this purpose (Figure 5).

As reported last year, one potential concern is that the FDA has decided—despite the myopia control data (especially data with orthokeratology that has shown significant slowing of axial length progression and reduction in myopia progression)—that a long-term study is necessary prior to approving these devices for myopia control purposes.²² That said, it is not improbable that an explosion in contact lens use for myopia control could occur sooner if consumer awareness is raised substantially.

MULTIFOCALS

New GP multifocal designs and refinement or expansion of current designs continue to enter the market. The design that is most widely used is some form of aspheric. There has been a transition from back-surface to front-surface (or combination) aspheric designs with the benefits of minimizing undesirable corneal topographic changes and greater effectiveness with higher-add wearers. The results of the GP Usage poll confirm this as respondents indicated that they fit, at minimum, half of their GP-multifocal-wearing patients into aspheric designs at a rate of three to four times that of segmented, translating, concentric, and scleral designs (Table 1).

The hybrid category continues to evolve and grow. One recent addition to the market was a center-distance design that has an adjustable central distance zone (1.8mm to 4.0mm) with add powers ranging from +0.75D to +5.00D in 0.25D steps. This design is recommended for emerging and early presbyopes and can also be used to complement the center-near design.

The scleral multifocal market should continue to grow as well. It is likely that designs will be introduced that have decentered optics to compensate for the tendency of scleral lenses to decenter temporally, optimizing vision at all distances.

OTHER NEW FINDINGS

Corneal GP lenses still have a prominent place in the GP lens toolbox (Table 2), and that should continue in the future. The vision benefits for patients having astigmatism and/or keratoconus are well established. Recently, the quality of vision of corneal GPs was compared to spectacle-wearing keratoconus.²³ The study showed that binocular resolution and stereoacuity improve from spectacles to GP contact lenses, with greater effect with bilateral (versus unilateral) keratoconus.

Optimizing initial comfort with corneal GPs has also been a topic of great interest for many years. Recently, the use of a topical anesthetic was compared to a saline-based placebo with first-time GP wearers.²⁴ The researchers concluded that anesthetic use resulted in both improved comfort and reduced anxiety during adaptation.

GP RESOURCES

There are an increasing number of resources to help eyecare practitioners (ECPs) in the design, fitting, and troubleshooting of any conceivable type of GP contact lens. Of course, the primary resource is always the laboratory consultant who can help with all questions pertaining to any particular GP lens design, and all laboratories’ web sites have fitting guides, calculators, and other useful resources to increase patient success with these lenses. It is certainly not inconceivable that the technology will be available soon that allows for laboratory consultants to see in real time what ECPs are viewing through the slit lamp and to make suggestions accordingly.

The GPLI has monthly webinars and a large number of resources on its web site for every category of contact lens design available. In addition, there are modules pertaining to staff education, coding and billing, and commonly asked questions of laboratory consultants. The Scleral Lens Education Society (SLS) has a number of educational programs, including workshops, lectures, and webinars on scleral lenses, as well as helpful resources on its website and a fellowship program available to ECPs. The American Academy of Orthokeratology and Myopia Control (AAOMC) also has several resources and programs in addition to a fellowship program for ECPs. Both the National Keratoconus Foundation (NKCF) and the International Keratoconus Academy (IKA) meet the needs of both patients and ECPs who need more information or assistance pertaining to keratoconus.

There are several large symposia that emphasize GP lenses. The Global Specialty Lens Symposium (GSLS)—which emphasizes all GP and specialty soft contact lenses—will be held Jan. 24 to Jan. 27, 2019 in Las Vegas. Likewise, Vision by Design, the annual meeting of the AAOMC, will be held May 15 to May 19, 2019 in San Antonio.

It’s important to note that a valuable resource for scleral lens education was introduced this past year: Contemporary Scleral Lenses: Theory and Application, from well-known scleral lens experts Drs. Melissa Barnett and Lynette Johns. It is a comprehensive clinical text pertaining to every scleral lens topic of interest. For more resources, check out “Beneficial GP Resources.”

GP LENS DEVELOPMENT IN THE NEXT FIVE YEARS

The comments made by laboratory consultants and contact lens specialists make it clear that there is much excitement about the current and future developments with GP lenses (see sidebars on pages 28 and 29). Scleral lens use will continue to grow, perhaps not at the rate of the past five years, but continual growth nevertheless. Responses gathered from the GPLI Advisory Board indicated that this was an area that they believed had the most potential in the next three years (Table 3).

As a greater understanding of scleral shape develops, designs—often with toric-back-surface peripheries—will be manufactured that provide greater alignment with the toric sclera. Additionally, as the imaging technology continues to advance, optical coherence tomography (OCT) will allow a better understanding of both center and peripheral fitting relationships. Also, the increasing use of corneo-scleral topographers will allow for not only the manufacture of a design that will align with both cornea and sclera, but also for the ability to order scleral lenses empirically. With the knowledge that scleral lenses are fit relatively tight and require a much greater center thickness compared to corneal GP designs, a soon-to-be introduced 200Dk lens material will help minimize potential hypoxia-related complications with scleral lens wear. The applications of scleral lenses for individuals who have ocular surface disease and can benefit from the resulting comfort, eye health, and vision received from the modality will likely increase as well. The next few years should also bring the introduction of, at minimum, one scleral lens filling solution that will be more compatible with corneal tissue than current systems are.

There is less certainty regarding what will occur with orthokeratology in the next few years. Without doubt, there is more interest in myopia control and orthokeratology, and we should see continued introduction of innovative new lens designs. Developments such as CooperVision’s acquisition of Paragon Vision Sciences could result in promotion of both soft and GP lenses that have demonstrated effectiveness for slowing myopia progression. Likewise, if any company that has a soft lens that demonstrates effectiveness in slowing myopia progression decides to promote this to the consumer media, orthokeratology could benefit as well. However, myopia control continues to be an off-label use of these specially designed contact lenses until the FDA rules otherwise.

GP multifocal designs with the ability to correct all levels of presbyopia will continue to be introduced. Time will tell how much of a factor scleral multifocal lens designs will be, but the high number of such designs available today make it likely that this market will continue to grow. With the knowledge that the nasal sclera is often more elevated than the temporal scleral is, potentially resulting in some temporal decentration of a scleral lens, the introduction of lenses with decentered optics should result in improved vision at all distances.

Surface coating technology has certainly exploded in the past two years and should continue as both scleral lens use increases and the benefits to the presbyopic population become more apparent. Likewise, the introduction of a solution to help refresh this coating should be forthcoming soon. We are also awaiting the next generation of hybrid designs, which continue to improve every year.

SUMMARY

The primary goal of ECPs is to optimize both the ocular health and the quality of vision of their patients. GP lenses play an important role in achieving these goals. In addition, this modality separates ECPs who simply prescribe contact lenses from those who fit the lenses that will best optimize their patients’ quality of life. Advancements in scleral lens design and instrumentation, complemented by increasing interest in both myopia control and presbyopic contact lens correction, ensure that GP lenses will continue to have a considerable impact in the years ahead. CLS

Acknowledgements: Roxanne Achong-Coan, OD; Josh Adams (Valley Contax); Mark André; David Bland (Bausch + Lomb); Mile Brujic, OD; Manoel Carvalho (Boston Foundation for Sight); Carmen Castellano, OD; Clark Chang, OD; Gloria Chiu, OD; Martin Conway (Contamac); Robert L. Davis, OD; Richard Dorer (Blanchard Contact Lenses); Barry Eiden, OD; Robert Ensley, OD; Melanie Frogozo, OD; John Gelles, OD; Linda Hammann (Precision Optics); John Hibbs (Contamac); Jason Jedlicka, OD; Mike Johnson (Art Optical); Beth Kinoshita, OD; Jamie Kuhn, OD; Karen Lee, OD; Mike Lipson, OD; Derek Louie, OD; Marsha Malooley, OD; Langis Michaud, OD; Troy Miller (AccuLens); Clarke Newman, OD; Heidi Noorany (SynergEyes); Keith Parker (AVT); Roxanna Potter, OD; Tom Quinn, OD, MS; Phyllis Rakow; Renee Reeder, OD; Susan Resnick, OD; Jack Schaeffer, OD; Ann Schakelford (ABB Optical); Louise Sclafani, OD; Muriel Schornack, OD; Brian Silverman, OD; Jeff Sonsino, OD; Jan Svochak (TruForm Optics); Maria Walker, OD; Jeff Walline, OD, PhD; Ron Watanabe, OD; Steve Webb (Metro Optics); and Stephanie Woo, OD.

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