|Quarterly newsletter on Soft Specialty Contact Lens |
Research, Developments, Designs and Materials FALL 2012
|WORLD WIDE VISION
Specialty Soft Lenses -
Almost 16 years ago, I wrote an article titled "In search of perfect vision" in which I discussed the opportunities and challenges associated with customized soft contact lens correction. That article explores the possibilities of correcting the higher order aberrations of the eye with soft lenses and the potential improvements in vision that might arise. With the subsequent advent of clinical Hartmann-Shack wavefront sensors (aberrometers), we now have a much better understanding of the nature and range of higher order aberrations that affect the eye, and there has been some significant progress in understanding the potential visual benefits of correcting higher order aberrations. This article will focus on the irregular cornea, myopia control and presbyopia in terms of aberration correction. Understanding the optics of the eye is the key to many of the big challenges and opportunities in vision correction with soft contact lenses. Click here for full report
Custom Soft Lenses to the Rescue
Large Diameter, Lens Fit, Custom Lens
John Mark Jackson, in Contact Lens Practice Pearls, a column of Contact Lens Spectrum, makes the case that custom-made soft lenses are imperative in contact lens practice. 'Custom Lenses to the Rescue' he states. An off-the-rack lens in one of his patients provided poor fitting characteristics, with a huge amount of lag visible on upgaze. The patient had a corneal diameter of 12.5mm as compared to the average 12mm. A custom-made lens with a diameter of 14.5mm provided a much improved lens fit with much better comfort. Custom soft contact lenses can make your practice stand out and create loyal patients in the process. 'When patients understand that you are making an extra effort to take care of their eyes, they will appreciate that they're in good hands' the author states.
|IN THE LITERATURE|
Effect of Single Vision Soft Contact Lenses on Peripheral Refraction
Peripheral Refraction, Myopia Progression, Soft Contact Lens
Pauline Kang et al from the University of New South Wales in Sydney, Australia looked at the role of commercially available soft lenses on peripheral refraction and possibly on myopia progression. They found that the soft lenses caused an absolute hyperopic defocus. This peripheral hyperopia may be a possible cause of myopia progression. As this study is limited to one design, different changes in peripheral defocus may be induced with other soft lens designs and with different back vertex powers. Also, the peripheral defocus varies among individuals, which may require a more individual-based correction method.
Kang, Fan, Oh, Trac, Zhang, Swarbrick - Optometry & Vision Science July 2012
|IN THE LITERATURE
Tear Film Exchange Beneath the Lens
Continuous Wear, RGP, Soft, Epithelial Permeability
While most people would agree that contact lens-induced hypoxia is a contributing factor to reduced corneal epithelial integrity, a study by Meng Lin et al in Berkeley, California (USA) suggests that other factors play a role as well including contact lens type; ethnicity; and ocular anatomy, such as lid aperture size and corneal curvature. But also the fit of the contact lens on the eye may play a role in this. In particular, it is plausible that the higher rate of post-lens aqueous tear flushing with RGP lenses in this continuous wear study was responsible for the lower epithelial permeability compared to the silicone hydrogel standard lenses, when hypoxia was excluded. Therefore, a better understanding of the tear flow dynamics during soft contact lens wear with different lens materials seems crucial.
Lin, Yeh, Graham, Truong, Hsiao, Wei, Louie - IOVS May 2012
|IN THE LITERATURE|
Custom-Made Soft Lenses
Post-LASIK, Lens Design Supported Software
Pascal Blaser and Stefan Facher, who previously wrote for the Soft Special Newsletter, published a clinical article in the German contact lens journal Die Kontaktlinse. In this article (in German) that is called 'Die Versorgung von irregularen Hornhauten mit weichen Kontaktlinsen,' they mention the important role that soft custom-made specialty lenses can play in today's contact lens practice. They report on a sophisticated online software program that helps them design the custom-made soft lenses. This can be particularly helpful in post-LASIK patients, they state, as RGP lenses may be extremely difficult to fit on oddly shaped corneas.
Die Kontaktlinse - 1-2/2012
Tips for Multifocal Soft Lens Fitting
Unequal Near Adds, Limit Uncorrected Astigmatism, Start Correcting Early
Craig Norman in the column 'Prescribing for Presbyopia' in Contact Lens Spectrum presents six quick tips for better soft lens multifocal results. The number one tip is: start correcting early to improve success down the line. Secondly: the refraction is crucial, and never over-minus a presbyopic lens wearer: in fact, try to push some 'plus.' A third one that is quite important is: consider unequal near adds. Being creative with near adds could prove beneficial. Fourthly: it is natural to consider more plus when near problems arise, but try less add first - you may be surprised by the results, according to Craig Norman. Number five is straight-forward, but very important: limit the amount of uncorrected astigmatism. Finally: follow the fitting guide. These are designed and tested specifically for the lens type used and could prove to have some excellent troubleshooting abilities.
Craig Norman - Contact Lens Spectrum September 2012
ISCLS & ECLSO 2012
Colored Soft Lenses, Scleral Soft Lenses, CXL and Soft Lenses & More
The International Society of Contact Lens Specialists (ISCLS) held its annual meeting in Ashford (UK). Many soft specialty lens topics were covered - such as (soft) prosthetic colored contact lenses (also see the bottom item on colored and tinted lenses in this newsletter), dissatisfied pseudophakic patients who could be managed with soft lenses, tear film exchange and improving lens shape. A highlight report of the meeting generated by Caroline Burnett Hodd can be found on the ISCLS website. In the same week, the European Contact Lens Society of Opthalmologists held its annual meeting in Nice (FR). Here, too, a range of topics was devoted to soft specialty lenses. Contact lenses for babies was one of the topics discussed, as was silicone hydrogel scleral lenses. Much attention was also devoted to corneal cross-linking (CXL) in keratoconus, where the suggestion was made that patients undergoing CXL may be corrected with (custom-) soft lenses without having to progress into RGP or scleral type lenses.
Phototherapeutic Keratectomy versus Alcohol Epitheliectomy/Debridement in Granular Dystrophy
Granular Dystrophy, Therapy, Bandage Soft Contact Lenses
The purpose of this case study was to compare the outcome of phototherapeutic keratectomy (PTK) and alcohol epitheliectomy with mechanical debridement for the superficial variant of granular dystrophy. In both cases a bandage soft lens was used postoperatively until the epithelium was healed. The visual outcomes of both techniques were similar, but the hyperopic shift with PTK is a concern. But the authors conclude that alcohol epitheliectomey can be used to treat superficial corneal dystrophies where PTK is unavailable. A bandage soft lens in both cases is desired. (photo: granular corneal dystrophy - B+L image library).
Incorporation of Color
into Specialty Soft Contact Lenses
Matt Lampa & Mark André
The tinted custom soft contact lens has applications from simple cosmetic color alterations to sport applications to full custom hand-painted prosthetic uses-all of which may dramatically improve patients' day-to-day visual and ocular performance. The translucent visibility tint absorbs roughly 5 - 15% of the light, whereas a translucent enhancement tint absorbs 20 - 30% of the light and is intended to alter cosmesis over the area tinted. As the desired cosmetic effect becomes more dramatic or is intended to mask disfigurement or to limit the amount light entering the eye, an opaque colored lens may be required. Click here for the full report on colored and tinted soft lenses.
This Newletter is Kindly