The GP market continues to be relatively stable in the United States. In the past year, it has been estimated that a total of 11% of contact lens fits and refits were with some form of rigid lens.¹ This is compared to 14% for 2017 and 9% in 2014.^2,3 Internationally, GPs—including overnight orthokeratology—accounted for 9% of fits in the past year.⁴

According to data obtained from Robert W. Baird & Co. (Jeff Johnson, OD, CFA, managing director, senior research analyst), an approximate estimate of the GP market size in 2019 would be greater than $400 million, which is divided into the following: orthokeratology, $117 million (up 14% from 2018); scleral lenses, $119 million (up 15% from 2018); and other GP lenses, $180 million (approximately the same as 2018).

The GP market appears to be especially benefitting 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 (CLS) readership poll, the results of which are provided throughout this article.

With a total of 125 respondents to this year’s survey, the overwhelming primary GP application continues to be conventional corneal designs (38%), followed by scleral contact lenses (26%) and then non-scleral contact lens designs for irregular corneas (11%), multifocal lenses (10%), and torics (9%) (Figure 1). As compared to the 2018 survey, the conventional corneal designs have decreased from 43%, and the scleral lenses have increased from 23%.⁵ Once again, it was encouraging that 94% of those responding to the survey fit GP lenses in their practice.

WHAT ARE THE MOST IMPORTANT DEVELOPMENTS IN THE LAST YEAR?

The GP Lens Institute (GPLI) Advisory Board of prominent specialty contact lens experts were surveyed as to what they believe was the most important new development in GP lenses in the last 12 months. The answers were very definitive and pertained almost exclusively to either one (or both) of the following innovations: 1) the introduction of a 200Dk material, and 2) scleral profilometry and profilometry-designed scleral lenses. In addition, the increasing availability (and use) of scleral back-surface toric haptics and quadrant-specific designs was noted by many respondents. Likewise, the availability of a polyethylene glycol (PEG)-based coating for use with additional lens materials was also a common response, as were hybrid lenses.

LENS MATERIAL DEVELOPMENTS

The introduction of a 200Dk lens material is the most well-received new development in the past year. With a flexural modulus of 1.341 MPa, it is relatively flexure-resistant for a hyper-permeable rigid material. Coming soon to the U.S. market is another 200Dk lens material that has been available in New Zealand and Australia since the summer of 2017 and in Europe for the past year. The U.S. Food and Drug Administration (FDA) clinical evaluation and approvals for the U.S. market are expected to be finalized by the end of 2019. The most important benefit of these materials is the increased oxygen transmission with scleral lens designs. The thickness of scleral lenses—in combination with the potential impact of the tear film between the lens and the cornea—make oxygen transmissibility an essential consideration when designing scleral lenses.

The wider availability of the previously mentioned PEG-based surface coating is an important development. It has proven to help provide optimum surface wettability, which is beneficial for individuals prone to deposits—especially those individuals who have ocular surface disease—as well as for noncompliant patients. In one study, Mickles compared PEG-coated versus untreated scleral lenses in subjects who had moderate-to-severe dry eye.⁶ It was determined that lens comfort was significantly better and dry eye symptoms improved with the treated scleral lenses compared to the untreated lenses. Lid wiper epitheliopathy and conjunctival papillae were also reduced with treated lens wear. And, the treated lenses resulted in both longer comfortable lens wearing times and less frequent lens fogging.

SCLERAL LENS DEVELOPMENTS

It is evident that scleral lens designs and accompanying technology continue to improve. And, as eyecare practitioners (ECPs) become more comfortable with fitting scleral lenses as a result of these innovations, this modality will continue to grow. According to the CLS reader poll, the results show that—of those fitting scleral lenses (27% indicated that they were not fitting these lenses)—only 5% of respondents indicated that their use had declined in the past 12 months (Figure 2). Also, 18% of respondents indicated that their use had increased greatly (up 4% from 2018), 29% indicated that their use had increased slightly, and 22% experienced no change. Overall, use increased for 17% of respondents, 19% reported no change, and 6% indicated that they had reduced their use of this modality.

The benefits of scleral lenses are well known and often life-changing. In patients who have ocular surface disease, sclerals may represent the only comfortable contact lens option, minimizing the symptoms that these individuals often experience while also providing visual correction. With irregular cornea patients, scleral lenses often represent a comfortable lens option that may prevent the need for a corneal surgical procedure. This was the conclusion of a recent study from Ling et al in which 2% of patients wearing scleral lenses required keratoplasty as compared to 7% of those who did not wear scleral lenses.⁷ Overall, scleral lens wear was associated with a 73% decreased risk of keratoplasty.⁷

Scleral lens designs continue to become more custom in nature in an effort to better align the lens periphery with the adjacent sclera. The incorporation of posterior-surface toric landing/haptic zones is now routine in scleral lens designs and is becoming commonplace due to our increasing understanding of scleral toricity; spherical haptics are becoming more of the exception to the rule. Quadrant-specific back surfaces are also increasingly available, as are notches, vaults, channels, and other modifications to allow more patients to benefit from scleral lens wear.

As mentioned previously, however, the most exciting development in scleral lenses in the past 12 months—and an area of great potential growth—has been the impact of scleral profilometry and profilometry-designed scleral lenses. Scleral profilometry allows practitioners to better align the landing zone of the lens to the sclera, resulting in improved efficiency and reduced chair time. The increasing popularity of scleral topography/mapping opens the door for empirical fitting, a method from which ECPs have benefitted with other GP designs (e.g., spherical, toric, multifocal, orthokeratology, and hybrid). Whereas impression molding is the gold standard for alignment of the lens to the sclera, the incorporation of lens design software into the scleral topography system should represent the next best alternative. With this custom free-form scleral lens design, there is no predetermined curve system; it is designed entirely from topography data. Therefore, custom haptics are generated from scleral topography, which makes fitting more objective and accurate.

A challenge to achieving the greatest clarity of vision—notably with irregular cornea patients—has been the negative impact of higher-order aberrations (HOAs). Much progress has been made in recent years, and several companies have developed designs with the capability to correct HOAs.⁸ There is much anticipation, however, for the introduction of scleral lens designs incorporating wavefront technology, which have been under development for several years. The team developing these lenses recently published the results of a crossover study in which subjects wore both best-conventional scleral lens correction and individualized wavefront-guided scleral lens correction.⁹ The authors determined that both residual HOAs and visual image quality improved with the wavefront-guided design.

The continuing question with regard to the future of scleral lenses is their role with patients who have healthy eyes (i.e., astigmats and presbyopes). Recently, Barnett reported on 16 healthy, astigmatic eyes fit into scleral designs (13 spherical, three front-surface toric) who had previously worn either soft toric or corneal GP lenses.¹⁰ Following one month of lens wear, subjects reported that scleral lenses were preferred over their previous correction in 14 of 16 (88%) of the eyes. The greater potential area for growth, based upon the number of designs that have recently been introduced, is in scleral multifocals. Scleral multifocal designs are evolving as ECPs become more comfortable with fitting them, and some of these designs now include decentered optics. Certainly, presbyopic individuals who have dry eye, as well as patients who are already wearing scleral lenses as they reach presbyopia, are good candidates. These designs are predominantly center-near due to the absence of translation, but the rigid optics make them a better option visually compared to soft multifocals.

During the past 12 months, clinical research has continued to guide practitioners as to what the challenges are with scleral lenses and how to meet those challenges. One such challenge that can result from the combination of the lens thickness and the thickness of the tear layer is the potential for corneal edema. Certainly, the introduction of 200Dk lens materials would help to reduce this potential complication. It has recently been reported that conventional scleral lenses prescribed today result in minimal (i.e., < 4%) corneal swelling when worn on a daily wear schedule.¹¹ However, other studies noted that extended wear of these lenses would be clinically unsafe.

The “hot button” with scleral lenses today is their impact on intraocular pressure (IOP). The results of two recent studies indicated that the IOP increased by an average of 4 mmHg to 6 mmHg, which is significant.^12,13 Practitioners can look forward to the results of future research in this area within the next 12 months.

ORTHOKERATOLOGY

In general, the interest in myopia control/management is escalating very quickly as a greater understanding of the negative long-term consequences of myopia—notably high myopia—has become apparent. The challenge lies in the fact that as this article goes to press, there aren’t any contact lenses that are currently being used for the purpose of slowing myopia growth that have been approved by the FDA, and it is unclear when any approvals may occur. Therefore, orthokeratology and soft peripheral-plus-power soft lenses are being used off-label for this purpose. While this means that no company can promote its product for myopia control, Jeffrey J. Walline, OD, PhD, notes that this does not mean that ECPs are not able to talk about myopia control with their patients, especially because numerous studies show a slowing of myopia progression with several different GP and soft lens designs.¹⁴ This is especially important because it is not unrealistic to think that a time will come in the near future when all myopic children will be using some form of treatment; most likely, they will be using contact lenses or a combination of contact lenses and pharmaceutical agents.

Our CLS reader poll found that overall, orthokeratology use increased among those fitting orthokeratology lenses (58% of respondents indicated that they were not using this modality) (Figure 3). When asked what contact lens and non-contact lens options comprise their myopia control program, soft multifocals again prevailed, with 46% of the respondents using this option (Figure 4). Orthokeratology was used by 31% for myopia control, followed by atropine (25%) and vision therapy (6%). It’s notable that the use of atropine has increased 4% in the past year.

The growth of orthokeratology can be attributed to many factors including the increasing interest in myopia control. In addition, more manufacturers have software programs for fabricating orthokeratology lenses that take into consideration corneal shape, elevation, and eccentricity, which can result in improved outcomes. The ability to successfully fit moderately astigmatic patients with currently available designs increases the number of individuals who can be successful with this modality. Anisomyopic children can also benefit; orthokeratology can reduce the amount of anisomyopia in children primarily through exhibiting a stronger effect in the more myopic eye.¹⁵

GP MULTIFOCALS

A number of innovations have recently occurred in the GP and hybrid multifocal arena. One recent multifocal design incorporates decentered optics to align the center-near zone over the visual axis. One has the multifocal optics on the front surface, with independently adjustable intermediate and near zones. Another has a center-distance multifocal design in which the fit can be customized based upon a patient’s pupil size, horizontal visible iris diameter (HVID), and add power. And, a new lensometer was introduced that can report power over the entire surface of the lens and can plot the power variation with respect to the lens radius.

According to the CLS readership poll, aspheric multifocal lens designs continue to predominate in the practices of those completing the survey (Table 1). More than 42% of the ECPs fit at least 50% of their GP multifocal-wearing patients into this modality. This is followed by concentric (13%), segmented, translating (13%), scleral (10%), and hybrid (7%).

IRREGULAR CORNEAS

Although scleral contact lenses are rapidly becoming the preferred choice for contact lens management of irregular corneas, the Scleral Lenses in Current Ophthalmic Practice (SCOPE) team conducted a survey of ECPs (n = 723 responses) and found that corneal GP lenses were the first option for 44% of respondents, whereas scleral lenses were the first option for 34% of respondents.¹⁶ This contrasts with our CLS readership poll in which almost 40% of respondents fit at least half of their irregular cornea patients into scleral lenses, followed by corneal GP (approximately 26%), intralimbal (10%), hybrid (8%), custom soft (8%), and piggyback (3%) (Table 2).

In a recent study¹⁷ that focused on contact lens options for keratoconus, the records of 301 eyes of 195 keratoconus patients who were prescribed contact lenses were evaluated. The authors concluded that soft toric and hybrid lenses were prescribed most often in mild keratoconus and that corneal GP and scleral lenses were selected for moderate or advanced disease. Having a central cone location and a history of corneal cross-linking (CXL) improved visual acuity more efficiently in the corneal GP group. Interestingly, the claim that CXL makes it easier for clinicians to prescribe contact lenses appears to be unfounded.¹⁸

FILLING SOLUTIONS

A recent case series demonstrated that using a commercially available buffered filling solution resulted in better subjective end-of-day comfort compared to using non-buffered saline as a filling solution.¹⁹ That said, to date there has not been a scleral filling solution introduced to the market that is both buffered and optimally compatible with the eye. Stay tuned for the potential introduction of such a solution in the next 12 months.

THE FUTURE

Scleral lenses will continue to grow in market share as more ECPs and patients learn how advantageous—and in some cases life-changing—they are, especially in the correction of irregular corneas. Scleral profilometry and lenses designed from this information will greatly increase in the next few years. Offset scleral optics for better correction of both HOAs and presbyopia will become quite common. Likewise, wavefront-guided scleral lenses will be introduced and should provide improved optics.

The ultimate outcomes will be more efficient and accurate scleral lens fitting, a higher percentage of successful patients, and a continuing decrease in the need for corneal transplants.

It is likely that we will see an increase in orthokeratology as the interest in myopia management escalates in the next few years. New systems of orthokeratology prescribing, fitting, and problem-solving will continue to improve refractive and myopia management outcomes. Hybrid lens technology will continue to evolve as well. The bottom line is that GP lenses will continue to be an important part of contact lens practice and can serve to differentiate a practice in the marketplace. Their role is best summarized by Thomas G. Quinn, OD, MS: “Of all the wonderful contact lens options currently available, GP designs (multifocal, toric, scleral, reshaping, etc.) are consistently the most significant ‘difference makers’ for my patients. They change lives in the most profound way.” CLS

Acknowledgements: Roxanne Achong-Coan, OD; Tom Arnold, OD; Melissa Barnett, OD; Dan Bell (Acuity Polymers); Cindy Belliveau (Visionary); Mile Brujic, OD; Karen Carrasquillo, OD, PhD; Carmen Castellano, OD; Gloria Chiu, OD; Martin Conway (Contamac); Robert L Davis, OD; Daniel Deligio, OD; Karen DeLoss, OD; Greg DeNaeyer, OD; Richard Dorer (Blanchard); Tim Edrington, OD, MS; Barry Eiden, OD; Robert Ensley, OD; Brandon Felkins (Tangible Science); Jennifer Fogt, OD; Melanie Frogozo, OD; Dan Fuller, OD; John Gelles, OD; Greg Gemoules, OD; Susan Gromacki, OD; Bob Grohe, OD; Jason Jedlicka, OD; Leah Johnson, OD (Paragon Vision Sciences); Mary Ann Kail (Essilor); Matt Kauffman, OD; Jamie Kuhn, OD; Karen Lee, OD; Mike Lipson, OD; Derek Louie, OD; Vic McCray, MD (Tangible Science); Marsha Malooley, OD; Robert Maynard, OD; Langis Michaud, OD; Bruce Morgan, OD; Clarke Newman, OD; Roxanna Potter, OD; Tom Quinn, OD, MS; Phyllis Rakow; Renee Reeder, OD; Susan Resnick, OD; Buddy Russell; Pam Satjawatcharaphong, OD; Jack Schaeffer, OD; Louise Sclafani, OD; Joe Shovlin, OD; Jeff Sonsino, OD; Loretta Szczotka-Flynn, OD, PhD; Gabi von Roedern (EyePrint Prosthetics); Maria Walker, OD, MS; Jeff Walline, OD, PhD; and Stephanie Woo, OD.

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