Highlights from the 2014 GSLS Meeting
Scleral lenses, specialty soft lenses, ocular shape, and lens discomfort were among this year’s topics.
By Edward S. Bennett, OD, MSEd, FAAO; Jason J. Nichols, OD, MPH, PhD, FAAO; Eef van der Worp, BOptom, PhD; Patrick J. Caroline, FAAO; & Craig W. Norman, FCLSA
The annual Global Specialty Lens Symposium (GSLS), held January 23 to 26, 2014 in Las Vegas and presented by Contact Lens Spectrum, demonstrated once again why it has evolved into one of the premier contact lens symposia in the world. With nearly 500 attendees, the program provided a wide variety of options for practitioners desiring to either incorporate specialty contact lenses or to enhance their abilities in fitting and problem-solving these designs in their respective practices. Almost 100 presentations, workshops, and panels were provided by internationally renowned faculty members, industry representatives, and invited scientific paper presenters. In addition, this year’s Poster Competition winners were chosen from among a record 68 scientific posters presented, and winners of the Photo Contest were selected from among 25 entries (Table 1).
First Place: Maria Walker, OD, Proposed Mechanism of Scleral Lens Induced Conjunctival Prolapse
Second Place: Josh Lotoczky, OD, FAAO, Livin’ on the Edge (Profile)
First Place: Norman E. Leach, OD, MS, Midday Visual Fogging in Scleral Lens Wearers: Does Fit Matter?
Second Place: Debby Yeung, OD, Scleral Lens Clearance Assessment by Biomicroscopy
PHOTOGRAPHY CONTEST (Winning Photos appear on this month’s cover)
First Place: Luciano Bastos, Profile View of the Cornea with Fluorescein
Second Place: Stephen P. Byrnes, OD, FAAO, Conjunctival Tenting at the Limbus Under a Scleral Lens
Third Place: Dr. Tomas Pförtner, Secondary Ectasia After Corneal Graft Fitted with Semi-Scleral Lens
Donald R. Korb, OD, FAAO, presented the 2014 GSLS Award of Excellence Lecture (Figure 1), which was titled “The Odyssey of Contact Lens Discomfort – The Journey to Resolution.”
Figure 1. Drs. Ed Bennett and Jason Nichols presenting the Global Specialty Lens Symposium Award of Excellence to Dr. Donald Korb.
In addition to the general sessions, numerous breakout courses presented information on areas such as scleral lens fitting, specialty contact lens coding and billing, corneal topography-based empirical fitting, and fitting children in contact lenses. There were no fewer than 48 manufacturers’ breakout sessions—often at breakfast, lunch, or at the end of the afternoon—at which attendees could learn how to fit and troubleshoot specific scleral lens designs, new multifocal and hybrid designs, new specialty silicone hydrogels, and corneal reshaping lenses. The GSLS was a “launch platform” for many new, exciting, and innovative contact lens designs.
The 2014 program was preceded by a series of four-hour specialty clinic sessions that focused on specific areas of interest. These sessions included “Myopia Control and Management,” presented by the Orthokeratology Academy of America; “Billing and Coding for Specialty Lenses,” presented by Dr. John Rumpakis; “Management of the Aging Eye,” which included multifocal contact lens patient selection, fitting, and troubleshooting strategies; and “Principles of Scleral Lens Fitting,” presented by the Scleral Lens Education Society.
State of the Contact Lens Field and Myopia Update
The general sessions on the first day included a state of the industry address from Contact Lens Spectrum Editor-in-Chief Dr. Jason Nichols. Based on information reported in Contact Lens Spectrum’s annual report article titled “Contact Lenses 2013” (Nichols, 2014), the size of the U.S. market was reported to be around $2.5 billion, while it was estimated to be approximately $7.6 billion worldwide. A few of the more interesting trends noted included the continued stagnation of U.S. silicone hydrogel growth, which was contrasted with another year of continued expansion of the daily disposable segment in the U.S. market. Depending on the source, daily disposables now make up approximately 20% of the U.S. market.
Following the contact lens industry update, Professor Brien Holden spoke about the worldwide myopia epidemic. He reported very high prevalence values—including longitudinal data from the United States. Vitale et al (2008) showed a substantial increase in myopia in the United States when comparing data available from the early 1970s (25% prevalence) to data from 1999-2004 (42% prevalence). Professor Holden also discussed the clinical impact of myopia, stressing the urgent need for greater awareness of retinal degenerations, such as degenerative myopia, which he noted is not currently recognized by major health organizations such as the World Health Organization. Lastly, current pharmaceutical and optical potential treatments were reviewed. Professor Holden discussed optical designs such as orthokeratology and aspheric multifocal contact lenses that have the potential to reduce myopia progression.
Scleral Lens Fitting and Troubleshooting
As in 2013, one of the most popular sessions pertained to managing corneal-scleral and scleral lens complications. This year’s was once again moderated by Patrick Caroline, FAAO, with panelists Drs. Langis Michaud, Loretta Szczotka-Flynn, Ann Pyck, Greg DeNaeyer, and Lynette Johns (Figure 2). The panel addressed several challenges in scleral lens fitting including:
Figure 2. The Managing Corneal-Scleral and Scleral Lens Complications panel: Patrick Caroline, FAAO, FCLSA; Langis Michaud, OD, MSc, FAAO(Dipl), FBCLA; Greg DeNaeyer, OD, FAAO; optometrist Ann Pyck; Lynette Johns, OD, FAAO; and Loretta Szczotka-Flynn, OD, PhD, FAAO.
Corneal Versus Scleral GP Lenses Many of the panelists indicated that while scleral lens use is greatly increasing, it is essential for all scleral-fitting practitioners to be proficient in designing and fitting corneal GP lenses. In the majority of irregular cornea cases, corneal lenses should be the initial lens of choice, with scleral lenses considered as an alternative, if needed. It was emphasized that there are still many unknowns and much to learn about scleral lens design and application.
Elevation and Scleral Lens Application Patrick Caroline reported research that he had performed at Pacific University with Randy Kojima based upon the meridional height difference in a total of 72 eyes. They concluded that when the difference in corneal height along any meridian is greater than 400 microns, a scleral lens design should be used. If a corneal design is fit on such a cornea, corneal bearing can occur where the cornea is highest and excessive clearance can occur where the cornea is lowest (Figure 3).
Figure 3. This eye had an elevation of +430µm and a depression of –260µm for a difference of 690µm in the same meridian, leading to a poor corneal GP fit.
Small Scleral Lenses (<16mm) Versus Large Scleral (≥16mm) Lenses Dr. Michaud, a renowned designer of small scleral lenses, discussed the benefits of these lenses versus larger scleral designs. Among the benefits are easier handling, improved physiological response, easier learning curve, less frequency of tight lens syndrome, reduced concern regarding conjunctival toricity (often more problematic with >16mm-diameter designs), fewer problems with post-lens clouding, and a lower likelihood of conjunctival prolapse. He also emphasized that hypoxia can be of greater concern with the larger designs, as he has found that the oxygen transmission through a corneal-scleral design can be several times greater than that through a full scleral due to the difference in lens thickness. He reported that at the limbus, a full scleral design has a Dk/t of 22.5 whereas corneal-scleral designs result in an average Dk/t of 49.6.
Scleral Lens Decentration Dr. DeNaeyer reported that there is a tendency for scleral lenses to decenter slightly inferior-temporal as a result of several factors including the overall lens mass, the effects of the upper lid pushing the lens inferiorly, and the scleral anatomy; the sclera is not spherical, and there is an elevation difference between the nasal and temporal sclera. The greater elevation of the nasal sclera is a factor in dislocating the lens temporally, which can cause issues such as discomfort and increased higher-order aberrations. This problem can be managed by selecting a smaller-diameter scleral lens or some other modality (e.g., corneal GP design or hybrid).
Dr. DeNaeyer also commented that there is a linear relationship between decentration and higher-order aberrations, with coma, in particular, decreasing best potential vision. He discussed innovative new software that can help determine where to decenter the optical zone to align optimally with the pupil center. This can significantly reduce coma. Therefore, this software can be used any time that vision is compromised due to decentration.
Large-Diameter Scleral Challenges Drs. Johns and DeNaeyer discussed the challenges of fitting large-diameter scleral lenses. Scleral toricity can be particularly problematic, especially because it increases in irregular cornea patients. Therefore, large spherical scleral lenses, in particular, may not fit optimally on the sclera, resulting in specific peripheral blanching, rocking, excessive movement, and possibly decentration. Conjunctival prolapse may also result. Patients can experience initial symptoms of awareness due to edge lift as well as long-term symptoms resulting from lens compression. Therefore, Drs. Johns and DeNaeyer recommend using toric peripheral curves in most larger-diameter (i.e., 18+mm) lenses.
Post-Lens Clouding Patrick Caroline reported that approximately 30% of large-diameter, medically indicated scleral contact lens wearers experience a significant decrease in vision after two to four hours due to solution contamination of the lens. Work performed by Dr. Maria Walker at Pacific University using oil-red-O stain found that although protein content was unchanged in the tear layer of these patients, the lipid content increased (Figure 4). It appears that this problem is greater with excessive lens clearance (i.e., >300 microns), which is not uncommon with these lenses. The clouding occurs less if a more viscous, nonpreserved tear is mixed half-and-half with a conventional, nonpreserved solution. Conventional, nonpreserved saline has no nutrients; the presenters noted that a solution that is more compatible with the eye is greatly needed for use with these designs.
Figure 4. Oil-red-O staining in a scleral lens wearer who does not experience post-lens tear film clouding (top) versus one who does (bottom).
COURTESY OF MARIA WALKER, OD, MS
Dry Eyes and Ocular Discomfort
The Odyssey of Contact Lens Discomfort – The Journey to Recovery As mentioned previously, Dr. Donald Korb gave the GSLS Award of Excellence Lecture on the subject of contact lens discomfort. He stated that the primary reason for half of all contact lens wearers ceasing lens wear is discomfort. Dr. Korb identified dryness as the contemporary leading cause of contact lens discomfort, with increased evaporation and evaporative stress with contact lenses as the mechanisms. Sequelae include tear film and blinking alterations, compromised lubricity-friction, lid wiper epitheliopathy, and hyperalgesia.
Dr. Korb emphasized that a contemporary introduction to dry eye should start with a quote from the recent International Workshop on Meibomian Gland Dysfunction (Nichols et al, 2011): “Meibomian gland dysfunction (MGD) may well be the leading cause of dry eye disease throughout the world.” We need to understand that the most common form of dry eye is evaporative. He stated that a primary feature and a root cause of evaporative dry eye is an inadequate lipid layer resulting from obstructive hyposecretory MGD. Dr. Korb also discussed the frequency of MGD in adults, which validates that MGD is the leading cause of dry eye disease.
Dr. Korb summarized by stating that resolution and treatment of contact lens discomfort requires a combination of two approaches. The first approach is through improved lens materials to better mimic a normal tear film, complete with lipid layer to minimize evaporation. He extended plaudits to the industry for recent improvements in this area. The second approach is to improve and restore meibomian gland functionality. Palliative treatment includes drugs; restorative treatment varies from warm compresses and manual expression to new sophisticated office treatments. Dr. Korb closed by stating that as the causes of discomfort are now understood, exciting progress in both areas will continue.
Tear Film and Ocular Surface Society’s (TFOS) Contact Lens Discomfort Workshop
The October 2013 special issue of Investigative Ophthalmology and Visual Science marked the completion of the TFOS International Workshop on Contact Lens Discomfort (CLDW) (Nichols et al, 2013). Drs. Jason Nichols, José González-Méijome, and William Miller represented the workshop’s participants at the GSLS, providing a two-hour overview of the workshop process and findings. Dr. Nichols, who chaired the TFOS CLDW, started the session by describing the 18-month process that involved 79 internationally known clinicians and scientists with a goal to establish an evidence-based consensus on various aspects of contact lens discomfort. There were eight subcommittees including those on definition and classification, epidemiology, materials/design and care, neurobiology, ocular surface and adnexa, tear film, outcomes, and treatment and management. Dr. Nichols also described the new definition for contact lens discomfort, and reviewed the findings of the epidemiology subcommittee.
Dr. González-Méijome discussed the findings of the materials/design and care subcommittee, including that many characteristics of soft lenses, such as oxygen permeability, wettability, dehydration, and most aspects of the lens design, have not been shown to be related to contact lens discomfort. That said, some compelling, albeit early, data suggests that the friction (or lack thereof) of contact lens surfaces matters in terms of comfort, in addition to the edge profile.
Dr. Miller concluded the session by discussing the findings of the management and therapy subcommittee. This subcommittee stressed the importance of first making sure that the ocular surface was free of any pre-existing disease (dry eye or MGD) in addition to making sure that the contact lens design, fit, and care were optimized. It is important to establish a baseline from which to implement treatments. All treatments considered in this process were chosen based on evidence for (or against) their use, but those considered most important included: optimizing the care system and regimen; moving to a more frequent replacement lens (daily disposable); changing the material; modifying diet; or using a lubricant or pharmaceutical agent.
Ocular Shape and Contact Lens Fitting
Determining the shape of the cornea can help contact lens fitters choose or design a contact lens that will optimize the cornea-lens relationship. Generally, mimicking the shape of the cornea promotes comfortable lens wear and reduces mechanical effects of the lens on the cornea. The group further questioned the following: how do we best analyze ocular surface shape and apply this knowledge to contact lens fitting? This was addressed by Eef van der Worp, BOptom, PhD, FAAO, in “An Overview of Ocular Surface Shape Instruments”; Lee Hall, BSc (Hons), MCOptom, in “Analyzing and Comparing Different Corneal Topography Systems”; and Chad Rosen, OD, in “Anterior Scleral Shape & Scleral Lens Fitting.”
Analyzing Ocular Surface Shape Dr. van der Worp noted that the standard procedure in contact lens practice is to measure the cornea with a keratometer. Keratometry typically measures the average curve of the central 3mm of the cornea in two meridians. A typical cornea is 11mm to 12mm in diameter; thus, a keratometer analyzes only 6% to 7% of the cornea. Contact lenses, in general, cover a much larger part of the cornea than 3mm, and a keratometer does not provide information about the periphery of the cornea—and thus, by default, cannot generate “shape” information.
Dr. van der Worp went on to say that corneal topography has been the backbone of specialty lens practices for a number of years—which is a huge step up from keratometry. Most corneal topographers in contact lens practice use the technique of reflecting alternating light and dark rings on the cornea developed by Portuguese ophthalmologist Antonio Plácido, and they cover a much larger surface area. Still, there is room for improvement, specifically regarding how much surface area can be measured and the accuracy of the peripheral measurement.
A newer instrument (Cassini [I-Optics]) features “color LED topography,” in which the traditional rings are replaced by colored light-emitting diodes (LEDs), which can help improve peripheral image quality and avoid a known disadvantage of traditional placido systems called “skew-ray error.”
Medmont recently developed a “composite map” for its E300 corneal topographer. The instrument takes five images of one eye (central, superior, inferior, temporal, and nasal) and uses software to merge them into one image, which considerably increases the surface area that can be observed. The resulting maps show limbus-to-limbus coverage.
Scheimpflug systems such as the Orbscan (Bausch + Lomb), Pentacam (Oculus), Galilei (Ziemer), and Sirius (CSO) instruments can analyze almost the entire cornea (anterior and posterior surface). In addition to a large surface area, they also measure elevation—e.g., they create a height map of the cornea. This may have many applications in contact lens practice, as height can represent ocular shape better than curves do. For example, a fluorescein pattern in GP fitting essentially shows a height map (where the fluorescein intensity represents the amount of elevation difference). Placido disc systems also are capable of generating height maps, though by calculation for curve data.
Stating that the session’s title was deliberately chosen to focus on ocular shape rather than just corneal shape, Dr. van der Worp also discussed the shape of the eye beyond the cornea. Optical coherence tomography (OCT) has allowed us for the first time ever to image the limbus and the anterior portion of the sclera. Dr. Rosen explored the shape of the limbus and the anterior ocular sclera in depth. This is highly relevant for fitting both scleral lenses and soft lenses.
The only disadvantage of OCT at this point may be that it only measures in single meridians (e.g., the horizontal or the vertical). A new instrument on the market that may be able to overcome this is Eaglet-Eye’s Eye Surface Profiler (ESP). This projection system needs the assistance of fluorescein to create a “screen” on the ocular surface. By analyzing a fringe pattern that is projected on the ocular surface, a 360º height map can be generated.
Lee Hall from the United Kingdom was able to show that every new development in the field of ocular surface shape analyzers mentioned in this overview could provide added value over previous, older techniques in terms of data available to eyecare practitioners to better predict the outcome of contact lens fits.
Limbal and Anterior Scleral Shape The second part of this session covered the topic of applying the knowledge that we have on ocular shape to contact lens fitting. With regard to scleral lens fitting, it was noted that the shape of the limbus and the anterior sclera is frequently tangential rather than curved. Also, many eyes are nonrotationally symmetrical in nature beyond the corneal borders.
Based on work done at Pacific University (van der Worp et al, 2014; Rosen, 2013), practitioners shouldn’t expect the limbal area and the anterior sclera to necessarily have the concave/convex shapes that might be expected when fitting/designing a scleral lens. It is suggested that using tangent angles rather than curves (or using very flat curves) may be appropriate in many cases when fitting scleral lenses. But large limbal and anterior scleral shape differences occur among meridians, even within the same eye.
What these results also indicate is that on an average eye, the ocular surface beyond the cornea is nonrotationally symmetrical in nature. It appears that, in an average eye, the entire nasal portion is typically flatter compared to the rest. Peter Marriott (1966), a British optometrist, was probably the first to describe this after looking at molds taken from eyes to manufacture haptic lenses. From the Pacific studies, it’s evident that this effect (of a flatter nasal appearance) is less for the limbal angles than for the scleral angles. The limbal angles are in approximately the same range and were not found to be statistically significantly different from each other. But in the sclera, this is not the case; remarkable differences exist, especially between the nasal region and the temporal-inferior area. It appears that on the scleral angles, the inferior segment is almost the benchmark, while the nasal angles are lower in comparison and the temporal angles are higher, with statistically significant differences between those. The increasing peripheral asymmetry noted may be related to the insertion of the extra-ocular muscles. Based on the results described above, it appears that for an average eye, nonrotationally symmetrical lenses—such as toric and quadrant-specific lenses, both of which are commercially available—could be necessary to optimally respect the shape of the eye. This is especially the case if the scleral lens diameter goes beyond 15.0mm.
“Elevating” Soft Lens Fit Information about the limbal shape is not of value for scleral lenses alone; in his PhD studies, Lee Hall showed that there is a link to soft lens fitting as well. Hall et al (2011, 2013) investigated the corneo-scleral junction (CSJ). They found that in normal eyes, the mean CSJ tends to be sharpest at the nasal side (and becomes progressively flatter at the inferior, temporal, and superior junctions), while in many cases the CSJ angles were within 1° of 180°, also indicating the most tangential extensions of the peripheral cornea to form the sclera. He also found a direct correlation between CSJ shape and soft lens fit, especially with lens movement.
Dr. van der Worp discussed using sagittal height information to fit soft lenses as an alternative to using the base curves printed on soft lens packages (usually expressed in numbers with or without mm). He said that similar to central keratometry values, the base curve value is probably not a reliable measure to predict soft lens fit. It is more often than not questionable as to whether the lens actually has an 8.3mm or 8.6mm spherical base curve on its back surface. Base curve equivalent (BCE) would perhaps be a more appropriate term. Aspheric designs also incorporate an eccentricity to mark a flattening toward the periphery, along with an edge lift—which all together form the total sagittal height across the total diameter of the lens. So the lens fit is certainly not defined by that single base curve number on the lens box.
The total sagittal height and diameter combination of the lens is of much more importance, and this should relate to the sagittal height of the anterior ocular surface and the shape of its limbus. In this session at the GSLS, the total ocular sagittal height (as measured with OCT and ESP) was compared to a series of commercially available silicone hydrogel two-week and monthly replacement lenses to better understand and predict soft lens fit—and to potentially put the “fitting” back into soft lens fitting.
Following are highlights of some of the 10 scientific free papers presented at the GSLS. Another paper, “Common factors in multifocal contact lens success” by Dr. Amy Dinardo, is discussed in the article, “Multifocal Lens Decision-Making 101” in this issue.
“Peripheral positive corneal power induced by orthokeratology reduces myopia progression” Dr. Jacinto Santodomingo discussed orthokeratology as a potential method to slow myopia progression and found that an increase in relative plus power in the paracentral and peripheral cornea induced by an orthokeratology lens design is associated with lower myopia progression.
“Variation of clearance with mini-scleral lenses” In a study pertaining to a specific small-diameter scleral lens, Dr. Michaud found, on average, that the tear fluid layer was reduced by (or settled) 75µm after six hours of lens wear.
“The influence of power and lens design on the zonal oxygen transmissibility of silicone hydrogel soft toric contact lenses” Tony Hough, BA, found that the actual Dk/t value in the optic and peripheral zones of silicone hydrogel toric contact lenses is significantly less than the reference values published by lens manufacturers. In general, for prismatic lenses, Dk/t decreases in clinically significant steps as sphere power becomes more positive, whereas lenses that feature dynamic stabilization maintain a fairly uniform Dk/t within the optic zone across the power range examined. The stabilization mechanisms employed for soft torics exert significant influence on Dk/t in the peripheral areas and also within the central optic zone. Therefore, manufacturers’ published reference values do not provide a useful guide for the Dk/t of modern silicone hydrogel soft torics.
“Contact lens fitting in subjects dissatisfied with visual results after Intra Corneal Ring implantation in keratoconus” Miguel Romero-Jimenez, DOO, MSc, reported on past Intacs (Odyssey Medical) patients who were fit with either a specific semi-scleral lens (Rose K2 XL [Menicon]) or a thick silicone hydrogel lens for irregular corneas (Kerasoft IC [B+L]). The author stated that high-order corneal aberrations and uncorrected visual acuity are the best predictors of what kind of contact lens (GP or thick soft) should be fitted on keratoconic corneas that have intracorneal ring segments. Higher values of corneal astigmatism and corneal asphericity increase the likelihood of needing a GP contact lens.
See What Specialty Contact Lenses Can Bring to Your Practice
Although the cutting-edge research in the free papers and scientific posters presented at the 2014 GSLS is an important component of the program, the primary emphasis of this symposium will always be the design, fitting, and troubleshooting of specialty contact lenses and how to effectively incorporate them into eyecare practice. Please join us for the next GSLS, which will take place Jan. 22 to 25, 2015 at Bally’s Hotel and Casino in Las Vegas. Information about the GSLS meeting is available at www.gslsymposium.com CLS
For references, please visit www.clspectrum.com/references.asp and click on document #221.
Dr. Bennett is assistant dean for Student Services and Alumni Relations at the University of Missouri-St. Louis College of Optometry and is executive director of the GP Lens Institute. You can reach him at email@example.com.
Dr. Nichols is the Kevin McDaid Vision Source Professor at the University of Houston College of Optometry as well as editor-in-chief of Contact Lens Spectrum and editor of the weekly email newsletter Contact Lenses Today. He has received research funding or lecture honoraria from Vistakon, Alcon, and Allergan.
Eef van der Worp is affiliated with the University of Maastricht as an associate researcher, a visiting scientist at Manchester University (Manchester, U.K.), an adjunct professor at the University of Montreal College of Optometry (Canada), and an adjunct assistant professor at Pacific University College of Optometry. He has received a research grant from Eaglet-Eye and educational grants from Bausch + Lomb Boston and Contamac.
Patrick Caroline is an associate professor of optometry at Pacific University. He is also a consultant to Contamac.
Craig Norman is director of Research, Michigan College of Optometry at Ferris State University. He is a fellow of the Contact Lens Society of America and is an advisor to the GP Lens Institute. You can reach him at CraigNorman@ferris.edu.