A Report from the 2013 GSLS Meeting
Scleral lenses and myopia control were among the hot topics at this year’s Global Specialty Lens Symposium.
|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 firstname.lastname@example.org.|
By Edward S. Bennett, OD, MSEd, FAAO
The fifth annual Global Specialty Lens Symposium (GSLS) took place Jan. 24 to 27, 2013 in Las Vegas and was once again very successful, with more than 500 attendees at this comprehensive clinical specialty contact lens program.
General sessions were held on myopia control, irregular cornea trouble-shooting, corneal topography/ocular shape, lens care, dry eye, presbyopia challenges, custom soft lenses, corneal cross-linking, scleral lenses versus conventional GP lenses, and the state of the contact lens industry.
In addition to the general sessions, one hallmark of the GSLS is that attendees can customize their schedule to their areas of interest. To that end, there were continuing education breakout sessions and no less than 41 non-continuing-education manufacturers’ breakout sessions, breakfast seminars, and lunch seminars helping attendees learn how to fit specific types of specialty lenses. The most popular breakout programs pertained to scleral lenses/irregular cornea management, corneal reshaping, multifocals, and coding and billing.
Another hallmark of the GSLS, those interested could attend sessions from four different four-hour fundamentals tracks immediately preceding the conference, including Fundamentals of Scleral Lens Fitting (Scleral Lens Education Society), Fundamentals of Corneal Reshaping (Orthokeratology Academy of America), Fundamentals of Irregular Cornea Fitting – Scleral Alternatives, and Fundamental Skills for Your Contact Lens Staff (Contact Lens Society of America).
The Scientific Poster and Photo Competitions were popular again this year (Figure 1). The sidebar on p. 25 discusses the most outstanding submissions. Finally, the first annual “Global Specialty Lens Symposium Award of Excellence” was presented to Professor Brien Holden (Figure 2), a very deserving icon and conference keynote speaker.
Figure 1. Clinical Poster first place winner, Southern College of Optometry student Erin Kindy with GSLS Program Committee member Dr. Ed Bennett.
Figure 2. Professor Brien Holden receiving the Global Specialty Lens Symposium Award of Excellence from Contact Lens Spectrum Editor-in-Chief Dr. Jason Nichols and GSLS Conference Chair Craig Norman.
Following are highlights from the education program presented at GSLS.
Sclerals, Sclerals, Sclerals
A very informative and popular session was moderated by Patrick Caroline, FAAO, FCLSA, pertaining to “Managing the Top 10 Large-Diameter Lens Complications.” The participants included Langis Michaud, OD; Clark Chang, OD; Christine Sindt, OD; Jason Jedlicka, OD; Halina Manczak, MD, PhD; and Melissa Barnett, OD (Figure 3).
Lens Settling A very important issue with scleral lenses today is that of avoiding mechanical pressure of the lens against cornea. Three important questions to answer are:
Figure 3. The Ten Top Complications Panel: Front Row (Left to right): Drs. Halina Manczak, Melissa Barnett, Clark Chang, and Christine Sindt; Top Row (left to right): Patrick Caroline (Moderator) and Drs. Jason Jedlicka and Langis Michaud.
Figure 4. A representative subject in a study reported by Patrick Caroline in which a total of 140 microns of scleral lens settling occurred (i.e., initially 410 microns of clearance, reducing to 270 after one month).
1. How much does the lens “settle” (i.e., reduction in the tear layer between lens and cornea) over time?
2. How long does it take for settling to occur?
3. How much central clearance is recommended initially and after settling?
Patrick Caroline reported on a study with 15 subjects at Pacific University in which they found that the lenses settled an average of 96 microns (ranging from 70 microns to 180 microns) over an eight-hour period. Eight hours did not represent the total time for lens settling, as the average reduction in clearance was 146 microns after one month (Figure 4). Patrick Caroline recommended central clearance (pre-settling) of 300 microns to 400 microns.
Dr. Michaud recommended 300 microns to 350 microns for larger lenses (i.e., ≥15.5mm), but for smaller scleral designs (i.e., 14mm to 15mm) he recommended no greater than 200 microns initially. However, he emphasized that, at minimum, 100 microns of clearance should be present after settling to minimize the risk of corneal compromise.
What Defines Excessive Clearance and How Should It Be Managed? The panel defined excessive clearance as greater than 500 microns initially on dispensing, although a lesser amount would be acceptable for smaller scleral designs (i.e., 14mm to 15mm in diameter). Excessive clearance can result in several problems including reduced visual quality due to the affect of a large vault on optics, too much negative pressure under the lens, and bubble formation on application. Overall, if the lens is exhibiting a tight fitting relationship because of too much clearance, vascularization can result in as little as seven days. Patrick Caroline indicated that less than 400 microns of clearance is acceptable for most lenses after settling has occurred; when in doubt, he recommended to err on the high side of tear lens thickness.
Clouding of Tear Film/Trapped Debris Behind Lens As many as 25 percent of scleral lens patients—notably those wearing larger-diameter lenses with greater vault and those individuals who have dry eyerelated disease—are prone to frequently experiencing a clouding of their vision. This results from an opaque substance in the tear film that could result from the accumulation of sebum that is caught under the lens and mucus that is sucked under the lens. The osmolarity and pH of the solution under the lens can change, which may also contribute to the problem. The longer that patients wear their lenses, the less this problem appears to occur. When present, patients often need to remove lenses every four hours to six hours and reapply them with fresh saline. However, they should resist the temptation to manipulate the lens on the eye, as this complicates the problem. Lens removal should occur only if the problem does not go away with lens wear. Notably, in patients who have severe ocular surface disease, the first month can be quite problematic due to mucus buildup. Touching the eye/lens or removing the lens can actually drive the mucus problem and make it worse.
|Poster and Photo Competition Winners|
Scientific Poster Competition
The 2013 GSLS featured more than 50 poster submissions. Winners were as follows:
First Place: Dustin Gardner, OD (lead author): “Investigation of Myopic Periphery Affecting Choroidal Thickness
Second Place: Masao Matsubara (lead author): “Topographical Change of Corneas after the Initiation of Mini-Scleral Lenses”
Clinical (Case-Based) Category
First Place: Erin Kindy (lead author): “Use of Daily Wear Multifocal Contact Lenses in the Treatment of Convergence Excess”
Second Place: Muriel Schornack, OD (lead author): “Toric Haptics in Scleral Lens Design: A Case Series
The Photo Competition included images in two categories: Contact Lenses, and Cornea/Conjunctiva/Lids. The winning photos are featured on this month’s cover and include:
First Place: Stephen P. Byrnes, OD, “Filtering Bleb Cascading over the Cornea Protected with a Soft Lens” (left on cover)
Second Place: Rudi Leysen, “Keratoconus UZAcornea3” (top right on cover)
Third Place: Prasad K. Sawant, “Meesmann’s Dystrophy in Early Keratoconus” (bottom right on cover)
What is the Risk of Hypoxia With These Patients? Are the Current Materials Adequate? Much recent research on this issue has been performed by Dr. Michaud. The large volume of tear film between lens and eye can present a limiting factor, as the Dk of tears is 80. As you increase clearance, you potentially increase corneal swelling. This, in combination with the excessive thickness (i.e., ≥250 microns) of these lenses both centrally and peripherally, necessitates a material Dk of (ideally) at least 250. As such materials do not yet exist, it is important to monitor scleral lens patients for signs of hypoxia.
Dr. Sindt does not fit patients who have abnormally low endothelial cell counts (i.e., <800). She reported that she had originally fit patients who had as low as a 600 cell count but, upon chart review, found that these were the individuals most at risk for hypoxia-related problems. Although severe problems such as corneal clouding and neovascularization do not occur until 8 percent to 10 percent swelling is present, the entire cornea and, in particular, limbal health must be closely monitored.
Patrick Caroline reported on a pilot study in which six subjects wore both 100-Dk scleral (350 micron center thickness) lenses and 100-Dk soft lenses for eight hours. The sclerals resulted in only 1 percent swelling; the soft lenses actually resulted in slight deswelling.
Of course, there is a delicate balance between increasing material Dk to minimize hypoxia and possibly having to later increase lens thickness due to flexure considerations.
Figure 5. The right eye of a subject in a study reported by Patrick Caroline in which a higher elevated sclera nasally resulted in greater temporal clearance several millimeters away from center than nasal (i.e., 430 microns versus 220 microns), which can result in the edge being more likely to embed into the nasal sclera.
Peripheral Lens Impingement/Embedding of Edge Although not required for assessing tear lens thickness under the lens, the use of optical coherence tomography (OCT) is very beneficial for assessing the relationship of the lens periphery/edge to both the limbus and the sclera. It is very important to have adequate limbal clearance with no pressure exhibited over the limbus, which would impact the limbal stem cells and long-term corneal health. Dr. Manczak recommended increasing the peripheral clearance in 50-micron steps. If using a design for which you reorder by flattening in steps, it is important to know how many microns that each step will increase clearance (for example, 35 microns per step). It is also important to observe where impingement/compression is occurring (i.e., at the limbus or at the edge). If the problem pertains to an inner curve, you could make the problem worse if you flatten the peripheral curve.
Why do Scleral Lenses Decenter? The beauty of scleral lenses, of course, is their stability and centration. According to Dr. Jedlicka, if a lens happens to decenter inferiorly, 90 percent of the time when you lift up the upper lid, the lens would then position centrally. Therefore, this is not a common problem. When present, it could result from a lens that exhibits excessive clearance or it could be due to the toricity of the sclera. In the latter case, Dr. Manczak recommended either tucking in the edge in the area of clearance or considering a toric periphery.
Of particular interest is that some of these lenses tend to decenter temporally. Patrick Caroline reported on results of the Pacific Scleral Shape Study indicating that the shape of the sclera may influence scleral lens position. In an 18-subject study evaluating scleral elevation, they found that in the right eyes of subjects, over a 15mm horizontal chord diameter, 15 of the 18 eyes had a higher nasal elevation, with a difference of 173 microns (Figure 5). At 20mm, all 18 eyes had a higher elevation nasally than temporally, with an average difference of 838 microns. The left eye horizontal difference was negligible at 15mm, but the nasal sclera at 20mm was elevated in all 18 eyes with an average difference of 659 microns. This could account for both why a lens may decenter slightly temporally and also why there may be a greater tendency for the nasal edge to embed into the sclera compared to the temporal edge. Interestingly, the height difference vertically between superior and inferior sclera was negligible.
Application Solutions Using a preservative-free solution for applying scleral lenses is essential to avoid potential long-term toxicity issues resulting from a preservative being in contact with the cornea. A popular application solution is sodium chloride inhalation solution (USP 0.9%). The pH of this is only 5, whereas many of the preservative-free solutions have a pH of 7; however, when the inhalation solution is first opened it actually has a pH of 7, then gradually decreases to 5—making the unit-dose application imperative.
Myopia Control: Today and Tomorrow
The session “Myopia Control Update” featured three outstanding researchers in this important and developing area: Brien Holden, PhD, DSc; Earl Smith, III, OD, PhD; and James Wolffsohn, PhD.
In his keynote address, Professor Holden, made it clear that myopia is a very significant and growing problem globally. He stated that 1.4 billion individuals are myopic worldwide, and that number should increase to 2.5 billion by the year 2020. In a 30-year period from 1972 to 2002, myopia increased from 25 percent to 46 percent in the United States. There has been an eight-fold increase in individuals exhibiting ≥8.00D of myopia. People with ≥3.00D of myopia have a three-times greater risk of glaucoma and a 10-times greater risk of retinal pathology.
Following up on the work originated by Dr. Smith at the University of Houston emphasizing the importance of decreasing peripheral retinal hyperopia to control axial length and to reduce myopia progression, Professor Holden discussed the results of a five-year, 40-subject study at the Brien Holden Vision Institute in Sydney, Australia. The mean age of the subjects was 12.7 years, and they were randomly placed into either a control group (i.e., standard hydrogel lens), or a test group (soft lens with peripheral plus power correction). An innovative new device, the BHVI Eye Mapper, was used to scan the retina and provide both central and peripheral refraction values. After 43 months, the peripheral plus design lenses had slowed the rate of progression of myopia by 40 percent and had reduced axial elongation by 47 percent versus the standard soft lens.
Professor Holden also commented that overnight orthokeratology appears to have the same effect, possibly because the reverse geometry design helps to convert relative hyperopia in the periphery to relative myopia. He also presented evidence that environmental factors can be important as well, indicating that increased outdoor activity and the use of high levels of illumination when performing near work both appear to result in less myopia progression.
Professor Holden believes that the use of customary spectacles and contact lenses can encourage myopia development, and his bottom line comments were very powerful: “We should fit every myopic child, young adult, and university student with peripheral plus power lenses,” he said.
Figure 6. Dry Eye Session faculty Drs. Jason Nichols and Kelly Nichols.
Where are We Currently With Meibomian Gland Dysfunction?
The dry eye session is always quite popular, and this year’s presentation was well worth it. Moderated by Contact Lens Spectrum Editor-in-Chief Jason Nichols, OD, MPH, PhD, and featuring internationally renowned dry eye expert, Kelly Nichols, OD, PhD, (Figure 6), the focus of this session pertained to what we know today about meibomian gland dysfunction (MGD) and its management.
Dr. Kelly Nichols reported on how large the dry eye market is today. Recent estimates of the U.S. artificial tear market are about $1 billion, with more than 15 products in some stage of development. She also discussed the current dry eye definition as developed by the International Dry Eye Workshop (www.tearfilm.org/tearfilm-reports-mgdreport.phphe).
Dr. Nichols also reviewed the current practice patterns for managing MGD including lid hygiene, warm compresses, and lid massage. In addition, she recommended lubricants in cases with additional dry eye; in moderate-to-severe cases, topical antibiotic ointment and/or topical steroids with systemic tetracyclines/derivatives were recommended. She also outlined the recommended method for warm compresses (Blackie et al, 2008). The towel used should be heated to about 45°C or 113°F, then reheat and have a replacement ready, performing this for at least four minutes. Another method is to pour one cup of uncooked white rice (or flaxseed) into a clean sock. Microwave the uncooked rice and sock for about 30 seconds. Gently massage upper and lower lids with this compress and then re-warm the sock and repeat.
Dr. Kelly Nichols also described the new LipiFlow Thermal Pulsation System (TearScience), in which heat is applied to the palpebral surfaces of the upper and lower eyelids directly over the meibomian glands, and a graded pulsatile pressure is delivered to the outer eyelid. A study by Lane et al (2012) indicated that the Lipiflow system was significantly more effective compared to a standard system and supported the use of this system in the treatment of MGD and dry eye symptoms.
Dr. Nichols completed her presentation by reviewing how she would manage a case of MGD. She would combine lid hygiene, LipiFlow if available, cyclosporine A or azithromycin (topical), lipid-based artificial tears q.i.d., topical steroid ointment (if possible), and 2g to 3g omega fatty acid supplementation a day. The patient would then be scheduled for a follow-up visit in six weeks to eight weeks.
Figure 7. Presbyopia Scientific Paper Presenters and Key-note address speaker: Bottom Row (left to right): Giancarlo Montani; Kristen Hovinga, MS; and Dr. Geunyoung Yoon. Back Row (left to right): Dr. Ed Bennett (Moderator) and Dr. James Wolffsohn (Keynote address).
Corneal Cross-Linking Update
Carina Koppen, MD, PhD, provided an exceptional and very comprehensive contemporary update on corneal cross-linking (CXL). CXL aims to strengthen the weakened cornea in mild-to-moderate keratoconus by improving its biomechanical characteristics. It stabilizes the shape of the cornea by increasing its rigidity via its effect on collagen cross-linking; it essentially artificially ages the cornea. Typically, the epithelium is abraded to allow penetration of riboflavin to enhance cross-linking. However, recent methods (i.e., “epi-on”) have not necessitated epithelium removal, resulting in increased safety (decreased risk of infection and epithelial healing problems) as well as better comfort to the patient. Such methods have included intrastromal application of riboflavin after pockets created by a femtosecond laser, injection of riboflavin into the stroma, changing the composition of the riboflavin drops (most promising), and electrophoresis.
Complications of CXL include failure in 7.5 percent of cases (decreased to <3 percent if Kmax >58D are excluded from treatment) (Koller, 2009). Corneal haze is quite common, ranging up to 90 percent with all eyes peaking at one month, leveling off at three months, then gradually disappearing after six months (Greenstein, 2010). Occasionally, a deep permanent stromal haze can occur. The risk of complications increases if corneal thickness is less than 400 microns.
Although CXL should theoretically result in a smoother optical surface for contact lens fitting, Dr. Koppen stated that this has not been her experience. In a study of 27 eyes, none of which were wearing contact lenses before CXL, 15 did not need contact lens correction afterward; 12 ended up being fit into GP lenses anywhere from one week to 10 weeks after CXL or as soon as the eye was quiet (Koppen, 2011). She concluded that CXL helped stabilize visual acuity, refraction, and topography in both groups of patients. Improvement of some topographic values (Kmax and I-S) was established only in the group of patients wearing contact lenses.
Her treatment paradigm for keratoconus is:
1. Progressive keratoconus and no need for optical correction: CXL.
2. Good tolerance for contact lenses or need for optical correction: contact lenses.
3. Intolerance to contact lens wear but need for optical correction: refractive surgery.
4. If best-lens-corrected visual acuity remains <0.5: transplant surgery.
Clinical Findings From the Scientific Paper Presentations
A total of 13 scientific papers were presented including a general topic session and a session specific to presbyopia correction (Figure 7). A highlight was Dr. Langis Michaud’s presentation on the oxygen permeability of scleral lenses. He performed calculations to determine whether scleral lens designs met or exceeded the Holden-Mertz daily wear oxygen transmission (Dk/t) criterion for an edema-free state of 24 for the central cornea and 33 for the limbal area (Holden and Mertz, 1984). He factored in both the effect of the tear layer and lens thickness. For a scleral lens manufactured in a 100-Dk material, the only way that the design could meet this criterion (and only the central criterion) would be if it was relatively thin (i.e., 250 microns) and the clearance was shallow (i.e., 100 microns). If the lens thickness was great (i.e., 500 microns) and the corneal clearance was 44 microns, the Dk/t decreases to only 10. If the Dk of the material was increased to 170, all of the lens thicknesses used resulted in acceptable results at 100 microns of clearance, and most at 150 microns. However, his bottom line finding was that a material would need to have a minimum Dk of 250 to provide an edema-free state for most scleral lens designs and fitting relationships.
A second clinical research study, coordinated by Dr. Michaud and presented by co-investigator Stephanie Woo, OD, compared a large-diameter (i.e., 14.3mm) GP lens to a commonly available soft toric lens in the correction of refractive astigmatism. In this multicenter study that included the University of Montreal, University of Missouri-St. Louis, Michigan College of Optometry, and Illinois College of Optometry, 40 asymptomatic soft lens wearers wore both scleral and soft toric lenses for a two-week period each. Vision, comfort, wearing time, and overall satisfaction were among the factors evaluated in this study. Of the 36 subjects who completed the study, 19 preferred to stay in the scleral lens, and 75 percent preferred the vision of the scleral design. Both comfort and wearing time were equal between the two groups.
Susan Resnick, OD, reported on her collaborative work with Donna Weiss, OD, as it pertained to fitting soft specialty lenses (i.e., NovaKone, Alden Optical) on 56 eyes manifesting an irregular cornea. These cases included keratoconus, pellucid marginal degeneration, post-LASIK ectasia, and post-intrastromal corneal rings. They found that the average visual acuity (VA) improved from 20/40–2 for the pre-fit manifest refraction to a post-fit VA of 20/25–1. Nearly 86 percent of the subjects achieved an improvement in best-corrected VA versus 14.3 percent exhibiting no improvement. Eighty-nine percent exhibited VA of 20/30 or better with these custom soft lenses versus 39.3 percent who had this level of best-corrected acuity prior to fitting. They concluded that in mild-to-moderate corneal ectasia, excellent visual acuity can be achieved with soft lens designs, notably in patients who are intolerant to GPs, or soft lens designs can serve as a viable intermediary step prior to GP wear.
See for Yourself
The Global Specialty Lens Symposium has evolved into one of the most popular and informative contact lens programs in the world. Conference Chair Craig Norman, FCLSA, said, “The 2013 GSLS was the best attended in the history of the event and provided contact lens practitioners from around the world with an update on the latest specialty contact lens products, procedures, and technologies,” Plan to attend next year’s GSLS, which will be held Jan. 23 to 26, 2014 at the Rio All-Suites Hotel and Casino, Las Vegas. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #209.