CONFERENCE HIGHTLIGHT GSLS
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SoftSpecialEdition is a quarterly newsletter that provides independent updates from the international literature on soft specialty lens-related topics. View as Webpage
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Soft Specialty Lenses @ GSLS 2021
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Recently, the Global Specialty Lens Symposium (GSLS) was held online with a staggering 4000 delegates registered and with 83 countries represented—truly a ‘global’ symposium. The number of presentations and especially posters dedicated directly or indirectly to soft specialty lens fitting was quite extensive - warranting a special edition of SoftSpecialEdition.com Newsletter. The conference actually started with a tribute to soft lenses, as this year marks the 50th anniversary of the modality. In the opening session, much attention was devoted to the history and the future of soft lens fitting. The myopia session was an exhibition of global excellence, with constant flowing around the globe, swinging back and forth from the East coast of Australia (Scott Read from the Queensland University of Technology in Brisbane and Kate Gifford of myopiaprofile.com) to the Netherlands (Jan Roelof Polling from Erasmus MC in Rotterdam) and North America (Langis Michaud, Université de Montréal in Canada). The session was titled "Customizing the treatment of the myopic child: ABC of a Myopia Practice ‘from Atropine to Zernike Polynomials.’” The latter referred to higher-order aberration and how this can be used to our advantage to optimize the outcome of the intervention. For more: the March issue of Contact Lens Spectrum is dedicated almost solely to myopia management, surely including soft multifocal lenses as an intervention method. But if the session at the symposium made one thing clear, it is that we will need to customize the treatment for myopia. Certainly in the soft lens arena, there are major opportunities for improvement. All GSLS 2021 lectures can be viewed on-demand on the GSLS website (free after registration).
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Variation in CL-SAG in DD, Reusable and Toric Lenses
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A session dedicated to 'The Soft Lens Dilemma' looked at how we can do better in terms of soft lens fitting in our practices. In this session, and in line with a topic covered in the winter softspecialedition.com edition, a paper on the variance in CL-SAG values was discussed. While the understanding of the overall sag values of the ocular surface (the OC-SAG) is increasing, the knowledge of CL-SAG values of different soft lenses that are used on a daily basis in clinical practice is limited. A study from Pacific University (USA) sheds some new light on the variation in CL-SAG among different lenses using a new instrument based on OCT technology that can directly measure posterior CL-SAG in a hydrated environment. The updated charts are available now on the Pacific University common knowledge website and will be updated going forward with additional lenses.
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Mari Fujimoto, assistant professor at Pacific University, shares an interesting case of a patient she saw with the students in clinic recently. This patient was habitually wearing the 8.8/14.0 Acuvue Oasys 2-week lens (CL-SAG 3456 microns) and was interested in a daily disposable lens option. Due to the lens riding high and close to the limbus, especially in upgaze (see movie below), it was decided to refit the patient with a deeper CL-SAG daily disposable lens that would respect the patient’s needs: an 8.5/14.2 Acuvue Moist lens (CL-SAG 3764). Knowing the sagittal depth information of lenses that we fit on a daily basis is not the answer to all of our problems in contact lens practice, but it could serve as a good starting point and aim us in the right direction when fitting soft lenses in clinical practice.
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Global Specialty Lens Symposium - Posters
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A poster by Stortelder, Montani and Rojas titled a Theoretical Model to Compare the SAG of Soft Lenses evaluated the CL-SAG values of measured lenses and performed a mathematical exercise to recalculate the labelled diameter to an arbitrary 14mm diameter. They concluded that the differences between flattest and steepest values of soft lenses, as reported in a 2015 paper, should be seen in relative terms. If recalculated to 14mm, the difference between flattest and steepest lens in that batch is smaller than originally reported. One could do the same (recalculating) exercise for average diameter, minimal diameter or maximal diameter - or another arbitrary 15mm diameter (the proposed 'workbench' on the ocular surface). The differences between the original and the recalculation are less in extent in those cases. But all in all, the poster raises a good point: the difference between commercially available lenses, as referred to in the paper above, may be even less than reported if the lenses are recalculated this way.
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Selecting the Most Valuable Parameter
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Improper lens fits account for about 20% of annual lens dropouts. In an effort to optimize soft contact lens fitting, Joselyn Dlouhy and Jason Jedlicka sought to determine which is the more valuable data parameter when selecting an initial lens: corneal curvature or corneal diameter. This data indicates that sagittal height prediction is more closely related to the curvature of a cornea rather than the horizontal visible iris diameter (HVID). HVID was proven to have a correlation of r close to 0, or no correlation when comparing data. Mean corneal curvature, however, showed a more positive correlation, suggesting that it is the more useful parameter. While HVID is important when considering diameter of the lens and coverage of the limbal zone, it falls short in determining the best-fit lens for soft contacts. If it is our desire to keep contact lens wearers happy in their lenses and to avoid dropouts among current and new lens wearers, then it is important to dispense well-fitting lenses. To achieve this outcome reliably, corneal curvature appears to be the more reliable measurement compared to corneal diameter to select a lens with the appropriate sagittal depth.
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Alyssa Invergo et al from Pacific University presented a case report on Custom Soft Lenses for Pellucid Marginal Degeneration (PMD). While scleral lenses can provide ideal optics and comfort for some individuals, they can be uncomfortable for others even when an optimal fit is obtained. In this case, custom soft lenses were able to provide the same acuity as the patient’s habitual scleral lenses while improving her comfort and ease of care. The novel soft lens used in this case for the patient’s left eye was designed to mimic a traditional scleral but in a silicone hydrogel material. The larger diameter (17.0 mm) and increased lens thickness (0.50 mm) allows the upper lid to induce lens movement and tear exchange with every blink. This tear exchange is vital to delivering oxygen to the cornea. If tear exchange was not achieved, hypoxia would likely result considering the greater lens thickness and subsequent lower Dk/t value. Challenges in Custom Soft Lens Fitting in a Case of Degenerative Myopia was presented by Xue Mei, Chad Rosen and Josh Lotoczky. Reported spectacle Rx in this case was -21.75 -8.25 x090 and -13.75 -5.75 x083. As the lens is made with increasing amounts of power, the lens thickness and weight increase. Consequently, issues around centration, lens/edge awareness, and oxygen transmissibility arise with higher-power lenses. The right lens exhibited excessive inferior decentration despite having similar corneal curvatures.
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Soft Custom Lenses Get the Job Done
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Priya Patel presented a poster 'Backtracking From Scleral Lenses: When Custom Soft Lenses Get the Job Done'. Soft contact lenses can be a viable option for therapeutic lens correction, it is stated. Scleral lenses can be considered an excellent choice for troubleshooting, but they cannot be the only option available for patients who are seeking a specialty contact lens. When presented with a patient who is not comfortable in their scleral lenses, a creative solution is often warranted to find an alternative solution. The case presented is of a 46-year-old white male teacher with a history of keratoconus OD>OS. To optimize comfort and to reduce the chance of redness, fogging, and irritation after lens removal as previously experienced with both corneal and scleral GP lenses, he was switched into a custom soft lens modality in both eyes. The result was a visual outcome of just shy of 20/20 in both eyes and a very satisfied patient.
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Ortho-k Effect of Everted Soft Lens
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Myopic LASIK results in an oblate cornea that may complicate the fit of a regular-geometry contact lens. Regression of myopia following LASIK may affect up to 10% of eyes with low to moderate myopia. This case presented by Mari Fujimoto from Pacific University explores overnight wear of an everted high-minus soft contact lens to induce an orthokeratology treatment on a patient experiencing post-LASIK refractive regression. Utilizing the reverse-geometry profile of an everted soft lens, an axial topographical profile that mimics a post-orthokeratology topography map was observed, and the patient reported clear and comfortable vision. The patient’s main concern was waking up in the middle of the night and not being able to see due to the significant minus power of the everted soft lenses. Further optimizing the central power of the lens and maintaining a thicker minus peripheral design may induce a similar effect with adequate vision through the soft lenses.
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The Beauty of Cosmetic Prosthetic Lenses
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Decision-Making in a Gray Area - An Unexpected Soft Prosthetic Lens Fitting: Soft prosthetic contact lenses are best recognized for their cosmetic benefits but can also be an invaluable therapeutic tool to combat symptoms of photophobia and glare. For many pathologies, these tinted or computer-generated iris print lenses can be duplicated year after year, but for eyes suffering from more serious complications, e.g. status-post keratoprosthesis (KPro), frequent refits are needed due to subtle changes in eye shape. These fits often require advanced lens troubleshooting strategies and creative solutions to satisfy the patients’ aesthetic and visual needs. Azinda Morrow proves that this is the case by presenting an interesting and creative solution for a 69-year-old Hispanic female status-post KPro OS who complained of poor cosmesis. Elizabeth Cho and Dawn Lam have another case report in this category: Covering up the Black Hole: Cosmesis, Visual Function, and Glare Control with Soft Prosthetic Lenses.
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Get Your Fit Right for Cosmetic Lenses
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Another interesting case report came from Thibaud Syre, optometrist, scleral lens specialist and orthokeratology lens practitioner from France. This was a case of a corneal infection post-surgery (cataract). Due to the fact that the cornea was really damaged, we first ordered a set of 3 unpainted trial lenses to determine the correct base curve. The lens was already in the final material and thickness, with a power of +3.00 to simulate the thickness of the painted lens: an 8.40 BC, 14.2mm diameter, with a negative flattening to limit the movement. I believe it is important to always fit cosmetic lenses as we fit a standard lens and to take the time to find the optimal geometry, ensuring optimal tolerance, centering and removal - apart from the desired cosmetic outcome.
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See link below for GSLS 2021 photo contest images.
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