A Report from GSLS 2010
A summary of highlights and key findings from the second Global Specialty Lens Symposium.
By Gregory J. Nixon, OD, FAAO
Dr. Nixon is an associate professor of clinical optometry and the extern coordinator at The Ohio University College of Optometry. He is also in a group private practice in Westerville, Ohio. He is on the Allergan Academic Advisory Board and the B+L Advisory Board.
The 2010 Global Specialty Lens Symposium (GSLS) took place from Jan. 28 to 31, 2010 in Las Vegas. This meeting began as the Global Keratoconus Congress, which for two years focused primarily on contact lens care and issues related to keratoconus and irregular corneas. For the past two years, GSLS has expanded to include a comprehensive agenda of specialty lens topics. New topics covered this year included specialty tinted lenses, lenses used in sports vision, and prevention and treatment of corneal ectatic disease. Another new feature this year was a pre-conference "Fundamentals" track that reviewed key elements of patient care and lens fitting guidelines for presbyopia and irregular astigmatism.
The GSLS was presented by the Wolters Kluwer Health Care Conference Group, with Contact Lens Spectrum as the exclusive media sponsor. Additionally, the conference was supported by more than 100 exhibitors representing 40 different companies and headlined by platinum sponsors Bausch + Lomb and Blanchard Contact Lens. The GSLS Education Planning Committee (Figure 1) of Pat Caroline, FAAO, FCLSA; Jason Nichols, OD, MPH, PhD, FAAO; Craig W. Norman, FCLSA; Ed Bennett, OD, MSEd, FAAO; and Eef van der Worp, BOptom, PhD, FAAO, FIACLE, FBCLA, planned a vibrant, insightful meeting with lectures, interactive expert panels, free papers, posters, industry breakfast seminars, breakout sessions, and workshops. There were more than 500 total attendees from 25 countries who enjoyed contemporary updates on the comprehensive field of specialty lens fitting.
Figure 1. 2010 GSLS Education Planning Committee: Pat Caroline, FAAO, FCLSA; Jason Nichols, OD, MPH, PhD, FAAO; Craig Norman, FCLSA; Ed Bennett, OD, MSEd, FAAO; and Eef van der Worp, BOptom, PhD, FAAO, FIACLE, FBCLA.
The following represents a summary of notable presentations from this year's conference. For a look at the full agenda, please visit www.healthcareconferencegroup.com/conferences.asp?conf=144.
Risks and Benefits of Ortho-k
Helen Swarbrick, PhD, Msc, BscOpt, presented a comprehensive overview of orthokeratology and the issues involved with this treatment regimen. She focused on one of the greatest risks, microbial keratitis (MK), balanced against the potential benefits of myopia control. She reported that it is commonly accepted that the refractive effects of ortho-k are created by thinning of the epithelial layers, centrally for myopia and midperipherally for hyperopia. Her laboratory's recent work considers whether orthokeratology-induced epithelial thinning compromises the corneal defenses, which might predispose an eye treated with ortho-k to MK. Research results thus far show no difference in epithelial desquamation rate or bacterial binding to epithelial cells between daily ortho-k lens wear and conventional GP lens wear. Furthermore, there was no difference between test eyes and control eyes wearing no lenses. Increased bacterial binding occurred only in the overnight subjects, suggesting that overnight eyelid closure may be the key risk factor for developing MK in ortho-k.
However, a retrospective study presented by Mark Bullimore, MCOptom, PhD, FAAO, showed that the risk of MK with overnight corneal reshaping lenses is similar to that of other overnight modalities. Additionally, further information surrounding the high occurrence rate of orthokeratology-related MK in China in 2001 has been shown to be associated with tap water use as a storage and disinfecting agent and uncontrolled distribution of ortho-k lenses.
Ortho-k and Myopia Control The possible myopia control effects of orthokeratology were previously presented in the Longitudinal Orthokeratology Research In Children (LORIC) study (Cho et al, 2005) and the Corneal Reshaping and Yearly Observation of Nearsightedness (CRAYON) study (Walline et al, 2007). S. Barry Eiden, OD, FAAO, presented a two-year interim report on the Stabilization of Myopia by Accelerated Reshaping Technique (SMART) study, which continued to show a correlation in the slowing of myopic progression with overnight corneal reshaping lenses in children. The results show the corneal reshaping group has a significantly less myopic best sphere correction from baseline measurements compared to controls (Test OD 0.09D, OS 0.08D versus Control OD 0.81D, OS 0.73D; OD and OS p<0.0001). However, there was no statistically significant change in axial length or vitreous chamber depth between the groups.
Additionally, Jacinto Santodomingo, MSc, PhD, MCOptom, FBCLA, FAAO, reviewed the Myopia Control with Orthokeratology contact lenses in Spain (MCOS) Study, in which continued documentation of safety outcomes for corneal reshaping in a pediatric population was evident by no changes in best-corrected visual acuity or significant adverse health effects from ortho-k wear.
The mounting evidence of ortho-k's effect on myopia progression has created an intriguing hypothesis about the mechanism by which ortho-k optical correction can slow myopic growth. Dr. Swarbrick reported on animal studies that suggest peripheral retinal image focus plays a key role in emmetropization, specifically that a hyperopic peripheral refraction may serve as a stimulus for axial length growth. Interestingly, light rays of a conventional contact lens (Figure 2) create a hyperopic defocus in the peripheral retina, which is similar to the results of wearing a spectacle lens. However, the peripheral light rays of a reverse geometry lens surface (Figure 3) create a peripheral retinal myopic defocus that may hinder myopic progression.
Figure 2. Myopic correction with a conventional contact lens creates a hyperopic defocus in the periphery that stimulates further increase in axial length.
Figure 3. Myopic correction with an orthokeratology lens design creates a myopic defocus in the periphery, which may slow myopic progression.
Additional benefits of ortho-k were presented by Jaume Pauné, Msc Optom & Vision. His work demonstrated the effectiveness of fitting ortho-k lenses on ectatic corneas following treatment with intrastromal corneal rings. The combined effect reduced cylinder correction and decreased higher-order aberrations beyond what either treatment could achieve independently.
Consistent with previous years, there has been tremendous growth in large-diameter lens fitting and in the availability of large-diameter lens designs. The overriding premise is that these lenses provide significantly enhanced stability by vaulting over diseased, ectatic (Figure 4), or irregular corneas and can provide consistent comfort and visual performance for some of our most challenging contact lens patients.
Figure 4. Advanced keratoconus.
Dr. van der Worp reviewed the challenging aspects of measuring and classifying scleral and limbal anatomy profiles that are critical to scleral lens fitting. His research has shown localized variability in the limbal angle formed between the cornea and the sclera, with the flattest angle occurring nasally and the steepest limbal angle occurring inferiorly. This information highlights the need for a commercially available instrument that can obtain reliable and repeatable measurements of limbal and scleral anatomy and perhaps the need for quadrant-specific scleral contact lenses.
But even without such technology, we continue to have a number of lens designs and diameters available to meet the individual needs of our patients. These can be subdivided into corneal-scleral lenses, mini-scleral lenses, and full scleral lenses, which vary in the degree of involvement with the cornea and limbus (Figure 5). Jason Jedlicka, OD, FAAO, highlighted the benefits of corneal-scleral lenses (13.5mm to 15mm) in that they provide improved comfort and stability over traditional corneal lenses, and they are less expensive and easier for patients to handle and wear compared to full scleral lenses. Despite the fact that these lenses still interact with the cornea, both Dr. Jedlicka and Renee Reeder, OD, FAAO, suggest that these lenses are a good alternative for both full- and part-time GP wearers because of the enhanced comfort effect with little to no adaptation.
Figure 5. Scleral versus mini-scleral lenses.
Stephen Byrnes, OD, FAAO, presented a number of mini-scleral lens designs (15mm to 18mm) that offer the benefit of completely vaulting over an irregular corneal surface to allow the resultant tear layer to correct the irregular astigmatism (Figure 6). Lynette Johns, OD, FAAO, provided an overview of using full scleral lenses (18mm to 24mm) that included the benefits of providing the greatest sagittal depths and reducing suction and compression complications.
Figure 6. Tear layer behind a scleral lens.
Techniques for fitting these large-diameter lenses were presented by an expert panel under the moderation of Michael A. Ward, MMSc, FAAO. One of the biggest challenges when initiating a complex lens fit on a highly irregular cornea is knowing where to start. Patrick Caroline suggested to simply choose the mean curvature on the topography map as the base curve radius of your initial trial lens. Loretta Szczotka-Flynn, OD, PhD, emphasized the importance of selecting the appropriate lens design within the large-diameter category. Specifically, oblate corneas often require reverse geometry lens designs, and those with a reverse curve greater than 5.00D will require a custom reverse geometry lens. Additionally, quadrant-specific lens designs can have tremendous value when significant asymmetry is present within the central cornea or especially in the peripheral cornea where edge clearance can vary dramatically from quadrant to quadrant.
Greg DeNaeyer, OD, FAAO, provided an overview of managing complications that occur with scleral lens fitting. It is important to specify center thickness (often 0.4mm to 1.0mm) on these large-diameter designs to reduce the risk of lens warpage. Additionally, when you encounter scleral lens sealoff you must flatten the scleral curve inside the area of blanching on the eye to provide the appropriate tear exchange. If reduced wearing time or foggy vision still results from reservoir debris, have your patients perform a midday rinse.
Michael Lipson, OD, FAAO, discussed the benefits of scleral contact lenses for use in severe dry eye secondary to chronic graft versus host disease (GVHD), most often triggered by a bone marrow transplant. A small case series demonstrated improved comfort, better vision, and less corneal staining in chronic GVHD patients wearing scleral lenses compared to no lens wear.
R. Doyle Stulting, MD, PhD, gave a compelling presentation on non-contact lens management and prevention of corneal ectatic disease. Dr. Stulting highlighted a number of case studies detailing the risk of surgery-induced ectasia following laser-assisted in situ keratomileusis (LASIK) surgery. The purpose was to identify proven risk factors for developing ectasia. Factors identified include keratoconus or forme fruste keratoconus, reduced calculated residual stromal bed, low preoperative corneal thickness, high myopia, and young age. Evaluate all of these factors using a Risk Score System that assigns point values to factors that increase risk of ectasia. Using this system, if the cumulative risk score is 4 or above, it is recommended to not perform LASIK to prevent the likelihood of post-operative ectasia.
Similar to the post-LASIK cornea, it is thought that the reduced thickness of keratoconic corneas can disrupt the corneal biomechanics and result in ectasia formation. Corneal cross-linking studies have been conducted to test the effectiveness of improving the structural integrity of corneal tissue to reverse or prevent further corneal steepening. The procedure involves placing riboflavin on the corneal surface (after epithelial debridement) then exciting it with UVA radiation (Figure 7), which generates reactive oxygen species that create covalent bonds between corneal collagen molecules. The process results in increased corneal rigidity that can decrease the maximal K value by about 1.00D over a three- to six-month period. Recent results have shown that corneal cross-linking is safe and can prevent progression of ectatic disease, potentially for an indefinite period of time.
Figure 7. Patient undergoing a corneal cross- linking procedure.
Contact Lens Care
Susan Gromacki, OD, MS, FAAO, led a discussion of the recent advances and continuing challenges in contact lens care. David Kading, OD, FAAO, reviewed the solution recalls that have occurred over the past few years and the introduction of new or repackaged products. These include Aquify (relabeled with new instructions from Ciba Vision), Renu Fresh Multi-Purpose Solution and Renu Sensitive Multi-Purpose Solution (formerly named ReNu MultiPlus and ReNu Multi-Purpose from Bausch + Lomb), Boston Improved Formula (a reformulation of Boston Original from Bausch + Lomb), and Opti-Free GP (formerly named Unique pH from Alcon).
Charlotte Joslin, OD, PhD, FAAO, reviewed the Food and Drug Administration (FDA) Lens Care Guidelines from 2008. Because these guidelines essentially emphasize compliance, Dr. Joslin illustrated the immense challenge of compliance adherence by presenting a compelling comparison of lens care to other conditions plagued by noncompliance such as tobacco use, obesity, and diabetes.
In addition to compliance, the remaining key is the development of novel lens care solutions that will maximize disinfection and minimize complications. Lyndon Jones, PhD, FCOptom, suggested that new solutions may be developed for use with specific lens materials, such as silicone hydrogel-specific solutions or hydrogel-specific solutions, to minimize surface deposition and lens non-wetting (Figure 8).
Figure 8. Contact lens non-wetting.
Specialty Soft Lenses
Although GP lenses are usually the specialty lens modality of choice, a number of presentations highlighted the use of soft contact lenses in specialty lens fitting. Gregory J. Nixon, OD, FAAO; Marco Van Beusekom, BOptom; and Mitch Cassel, OD, provided an overview of tinted and opaque colored soft lenses and their uses. Colored lenses can be used for many purposes, anywhere from elective cosmetic effects that enhance or change eye color to elaborate prosthetic lens designs that produce a dramatic cosmetic impression. Cosmetic lenses are used in television and movie productions as an extension of makeup, but colored lenses often have the most dramatic impact when they serve as prosthetic devices to restore cosmesis to damaged or disfigured eyes.
Advances in manufacturing have also resulted in soft lens designs to correct advanced refractive errors including astigmatic, multifocal, and irregular refractive error designs. In addition to optical benefits, Mark André, FAAO, FCLSA, reviewed the benefits of custom designed hydrogel lenses to aid in fitting a wide variety of corneal curvatures and diameters. He reported that nearly 50 percent of the population have corneal diameters that fall outside of the "normal" range of 11.6mm to 12mm, which can dramatically affect the sagittal depth and their ability to be fit with prepackaged lenses in established base curves and diameters. Many companies offer customized lens ordering in which you can specify base curves and diameters to the necessary parameters of a given patient.
Lynn White, MSc, FCOptom, discussed the KeraSoft (UltraVision, United Kingdom) lens for treating keratoconus. While not currently available in the United States, the KeraSoft lens is available abroad in a lathable silicone hydrogel material to reduce concerns of hypoxia and lens dehydration. The lens offers a wide range of parameters including astigmatic, reverse geometry, and sector-specific designs that can treat a wide range of conditions including keratoconus, pellucid marginal degeneration, and post-surgical irregular corneas.
Leslie Donahue reviewed the parameter extension of CooperVision's Proclear Multifocal, Proclear Multifocal XR, and Proclear Multifocal Toric lens designs. They have sphere power availability from ±20.00D, add powers from +1.00D to +4.00D in 0.50D steps, and the toric multifocal offers cylinder powers from −0.75D to −5.75D in 0.50D steps with around-the-clock axes every 5 degrees. All of these lenses are also available in both dominant (centerdistance) and non-dominant (center-near) designs.
When using any soft multifocal contact lens, Mark André emphasized the importance of measuring angle lambda (the difference between the line of sight and the center of the pupil defining the geometric axis) on patients to determine their success in this modality. Because a soft contact lens aligns with the geometric axis of the eye, if there is a large angle lambda, patients may have impaired vision with soft multifocal lenses because they are not viewing through the central optics of the lens.
In addition to advanced soft lens designs, even standard soft spherical lenses can be utilized to aid the treatment of some advanced corneal cases. Paul Rose, OD, FNZCLS, suggested using a high pluspowered silicone hydrogel lens to aid centration of a GP lens in piggyback cases. When doing so, he said that for each diopter of plus power in the soft lens, the GP lens must be steepened by 0.15mm to 0.2mm. Loretta Szczotka-Flynn, OD, PhD, MS, FAAO, who also employs this piggyback philosophy, reminded us that the soft lens used in a piggyback system will have approximately 22 percent effective power of the labeled power on the lens.
Fraser C. Horn, OD, reviewed the impact that soft lenses can have for athletes. Contact lenses often provide an athlete with better optics and peripheral awareness compared to spectacles. In addition to correcting refractive error, contact lenses can provide ultraviolet protection for outdoor sports. Even though sports-specific tinted lenses are no longer available as prepackaged products, there is a growing interest in having lenses custom tinted for a sportsspecific purpose.
Hybrid Contact Lenses
With the resurgence in hybrid lens technology and fitting, Alan Saks, MCOptom, FAAO, highlighted the pros and cons of this modality. The soft skirt designs with a GP center can provide great optics with the added benefit of improved centration and comfort over traditional GP designs. However, in spite of the relatively high Dk provided by the GP portion of the lens, the low Dk of the skirt can induce hypoxic complications of corneal neovascularization and corneal edema. A new generation of hybrids with a GP center Dk of 130 and a soft skirt Dk of 85 are currently awaiting FDA approval. Until then, some fitting methods can be employed to reduce the incidence of hypoxia-related complications. Dr. Eiden suggested an alternate fitting approach that fits both the base curve and skirt curve flatter than what the manufacturer recommends. The method employed by the EyeVis Eye & Vision Research Institute fits a standard cornea only 0.50D steeper than K (compared to 1.50D) and utilizes a skirt curve 1.3mm flatter than the base curve (compared to 1.0mm flatter).
This year's GSLS meeting went beyond contact lens management of presbyopia by exploring some of the advances in surgical presbyopia management. Dr. Stulting reviewed the challenges and limitations that have plagued the existing multifocal and accommodating intraocular lenses (IOLs), namely the optical aberrations that impair visual quality. Although a number of unique and compelling surgical possibilities are currently being investigated, Dr. Stulting introduced some initially favorable data on the Synchrony (Abbott Medical Optics) lens, a newly developed dual optic IOL that is currently in phase III FDA studies. Specifically, Synchrony (Figure 9) has demonstrated improved binocular visual acuity and contrast sensitivity with diminished complaints of glare and halos when compared to current commercially available multifocal IOLs.
Figure 9. Retroillumination view of the Synchrony lens.
An expert panel including Craig Norman, Ron Beerten, BOptom, FBCLA, Dr. Bennett, and Catherine Peyre, MD, discussed current strategies in contact lens management of presbyopia. There was consensus on increased utilization of multifocal lens designs as opposed to monovision. Vast improvements in GP multifocal engineering have made empirical ordering of aspheric GP multifocals a growing trend. Oftentimes, the initial empirical lens will have similar success to one ordered after utilizing a multifocal fitting set. The obvious advantage is diminished initial chair time. However, future office visits to troubleshoot the lens fit and prescription remain a key to successful outcomes of multifocal fittings. Because multifocals remain limited in their ability to provide consistently clear vision at distance, intermediate, and near, it is imperative to allow patients to test the lenses at home and at work and then refine vision at the distances that are most critical to their needs.
Despite all of the intricacies of lens designs and fitting techniques, one of the biggest challenges we face is that of increasing awareness of multifocal lenses to our patients. A recent survey conducted by the Gas Permeable Lens Institute showed that many patients remain unaware of the existence of multifocal contact lens options.
Dry Eye and Contact Lenses
Dry eye and ocular surface disease have a tremendous impact on the success of contact lens wear. Therefore, companies make continuous efforts to create lenses, solutions, and pharmaceutical agents that address dry eye itself and the side effects that dry eye inflicts. Dr. Nichols presented data from the Contact Lens Spectrum dry eye report from July 2009 that highlighted how practitioners currently manage dry eye. The most common method employed to address contact lens-related dry eye complaints was to refit into a different lens material, usually a silicone hydrogel. The other top methods included the use of artificial tears and changing care solutions, especially if a patient is using a PHMB-preserved solution.
Because artificial tears really treat only the symptoms and not the cause, Alan Saks, MCOptom, reviewed additional treatment methods with an emphasis on improving patients' natural tear function. This includes improved lid hygiene, lid massage to aid gland expression, and blinking to promote tear production and distribution. In addition to enhancing tears, it is important to avoid substances that can harm tear stability such as solution preservatives, oils from soaps and lotions, and systemic medications, which can cause dehydrating effects. When symptoms still persist, medical treatments such as topical cyclosporine and supplements such as omega 3 may also be helpful.
Dr. Jones provided insight into current research strategies to address the issue of contact lens-related dry eye. As dry eye has been noted to occur in up to 50 percent of lens wearers compared to just 25 percent of non-lens wearers, there is a compelling need to address how the contact lens materials we prescribe interact with the tears and ocular surface. Current theories suggest that lens dehydration, reduced wettability, and increased deposition have a correlation with increased dry eye symptoms. While the research evidence is too weak to support direct correlations, significant future studies are underway in developing novel contact lens materials that will have little to no surface deposition, dehydration, or induced friction forces.
There are significant correlations between dry eye and ocular allergies, and one currently accepted strategy to manage allergy-induced dry eye is instillation of topical antihistamines before and after lens wear. Efforts are currently underway to embed anti-allergy or anti-inflammatory pharmaceuticals into a contact lens to provide continuous drug delivery during contact lens wear. In addition, 26 new drugs are being investigated for the treatment of dry eye. For information on the status of current clinical trials and other information related to dry eye, visit www.dryeyezone.com.
One such future dry eye therapy may involve the use of testosterone cream as described by Charles G. Connor, OD, PhD. He presented a small study conducted using 5% testosterone cream applied twice daily to the periorbital tissue in menopausal women suffering from dry eye symptoms. Although there were no controls, treated subjects showed increased tear breakup time, increased Schirmer values, and increased contact lens wearing time.
Pediatrics and Contact Lenses
Jeffrey J. Walline, OD, PhD, presented results of the Contact Lenses in Pediatrics (CLIP) and the Adolescent and Child Health Initiative to Encourage Vision Empowerment (ACHIEVE) studies that highlight the safety and effectiveness of fitting children in contact lenses. Children were successfully fit in contact lenses and showed no difference in developing complications at three-month or six-month follow-up visits when compared to teenage lens wearers. Their only difference compared to teenage wearers was that children required 11 more minutes for application and removal training on average.
Florence Malet, MD, emphasized that you must communicate the process of contact lens fitting and wear to parents to fully educate and engage them and to maximize successful pediatric fitting. Marco Van Beusekom, BOptom, and Buddy Russell, FCLSA, discussed common medically related uses of contact lenses in children, particularly pediatric aphakia. Whether utilizing GP or soft lenses, they emphasized the importance of maximizing Dk to allow for sufficient oxygen transmission in these thick lenses that will need to be worn for a lifetime. Fortunately in Europe, custom silicone hydrogels are available that are beneficial for aphakic fits. Additionally, with the crystalline lens removed in these patients, UV absorptive materials are essential.
Don't Miss Out
This year's GSLS conference was a huge success and continued to build on its reputation as a leading meeting for specialty contact lens fitters. Please join us for the 2011 Global Specialty Lens Symposium, which will take place from Jan. 27 to 30, 2011 in Las Vegas. CLS