|Quarterly newsletter on Soft Specialty Contact Lens |
Research, Developments, Designs and Materials SPRING 2012
|WORLD WIDE VISION
Decoding the Future of the Specialist Lens Business: Opportunities and Threats
The introduction of custom soft lenses manufactured in silicone hydrogel may prove to be a great new opportunity for the contact lens practice. There are at least two areas of application for these new custom soft lenses: specialist applications such as managing keratoconus, and their use for ordinary corrections as a means of practice building (no internet source for replacement lenses). This represents a sizeable market; indeed if only a small percentage of the potential were achieved, then it would generate substantial growth within the specialist business. The upside is that in the past fifteen years, manufacturing technology has greatly improved. The quality and consistency of lathe cut lenses can rival that of high volume moulded lenses. The development of custom silicone hydrogel soft lenses for both specialist and regular use presents the specialist manufacturing industry with an opportunity to reverse the decline of the past two decades and to look forward to a period of growth with custom soft lenses gradually replacing custom rigid lenses. But to grasp this opportunity, industry management needs to refocus its priorities, especially to strengthen its representation to governments who increasingly promise an end to pointless regulation. Can the industry grasp this new initiative? Click here for full report
|IN THE LITERATURE|
Optical Quality of Soft Keratoconus Lens
Visual Performance, Keratoconus & Soft Lenses
A study published in the journal of the British Contact Lens Association, Contact Lens & Anterior Eye, compared a specialty soft keratoconus lens to a specialty RGP keratoconus lens. The retrospective study evaluated 94 eyes fitted with the soft keratoconus lens compared to 77 eyes fitted with RGP lenses. No difference in either visual acuity or wearing time could be found between the groups. More corneal staining was seen in the RGP lens group. The author concluded that soft specialty keratoconus lenses may be a good alternative for the optical management of irregular corneal astigmatism in non-surgical corneal ectasias such as keratoconus and pellucid marginal degeneration.
In another study published in Ophthalmic and Physiological Optics, Jinabhai et al evaluated visual performance in keratoconic patients using standard toric soft contact lenses, rigid gas permeable contact lenses and spectacle lens correction. While the RGP lenses provided the best visual performance, the standard soft toric lenses were successful in significantly reducing uncorrected higher-order aberrations compared to spectacles. No custom made soft lenses were used in this study.
|IN THE NEWS|
Multifocal Soft Contact Lenses
Presbyopia, Astigmatism & Topography
In Contact Lenses Today, Ron Watanabe discusses Astigmatism and Presbyopia. 'One segment of the presbyopic population that may be missing out is the astigmatic group,' and, 'Their vision will be somewhat compromised with soft (non-toric) multifocals, and they may be unable or unwilling to adapt to GP multifocals,' he states in his editorial. Several lens options are named that are available to practitioners, as the choices are getting better and better for these patients - a not insignificant group of lens wearers.
Patrick Caroline and Mark André in Contact Lens Spectrum look at two phenomena that may interfere with multifocal soft lens fitting and may be fairly easy to diagnose. Based on a poster presented at the Global Specialty Lens Symposium in Las Vegas by Matthew Lampa and Kevin So, it is evident through performing topography over multifocal lenses on-eye that although lens centration of the soft multifocal lenses was optimal, the line of sight was not necessarily in line with the lens optics. In a number of lens designs, they found the line of sight to be nasally oriented as compared to the optics of the lens on-eye. In addition, the article states, age-related decrease in pupil size adds to this problem, which makes it increasingly difficult for the presbyopic eye to accept this aberration.
|ON THE WEB
Soft Toric Calculator
Soft Lens Power, Over-refraction & Inclincation
John Mark Jackson, in Contact Lens Spectrum, discusses soft toric calculators. To name a few, the article refers to Ophthalmicalc, an online application from the University of Melbourne (AU), the ToriTrack calculator (Coopervision), EyeDock.com, which is a subscription website, and lastly OptiCalc, which is an iPhone app with several contact lens tools, including one to calculate soft toric lens powers after over-refraction.
Not All Lenses Fit the Same
Materials that do not loose as much water may have to be fitted steeper
Another column in Contact Lenses Today written by Ron Watanabe reports on basic soft lens fitting adjustments. In his editorial he argued that newer materials do not lose as much water as regular hydrogels on the eye, including the custom latheable silicone hydrogel material Definitive (Contmac Ltd) due to a unique polymer chemistry. Therefore, the lens does not tighten up on-eye, and a steeper base curve than usual may be needed to provide on-eye stability with these lenses, according to the editorial.
|CLINICAL REPORT I
Custom Made Soft Lens Case Reports
Keratoconus, wavefront corrected customization
Barry Eiden and Greg DeNaeyer in Contact Lens Spectrum present a number of case reports discussing the application of specialty soft lenses. All four cases describe patients with variable degrees of keratoconus and how these patients benefit from specialty soft lenses. They also take a look at the use of customized wavefront corrected soft lenses for keratoconus. Also in Contact Lens Spetrum, Patrick Caroline and Mark André present a case of a 45-year-old patient with a 20-year history of keratoconus and intracorneal ring implants. The patient was fitted with a Kerasoft (B+L) lens, a dual aspheric (both posterior and anterior surface) lens design in silicone hydrogel material. The patient's right eye improved from an uncorrected 20/200 vision to a stable 20/30 with this correction. With standard soft toric lenses, the visual acuity did not exceed 20/40.
|CLINICAL REPORT II
Large Diameter Soft Lenses
Treatment of Corneal Dellen after Pterygium and Recurrent Erosion
Contact Lens & Anterior Eye features a case report by Kymiosis et al in which a patient developed a corneal dellen after pterygium surgical treatment. Corneal dellen is characterized by corneal thinning, usually at the limbus with an elliptical shape. The lesion was 1.3mm by 2.7mm in size (length and height). The lesion did not respond to treatment, and at one week no improvement was noted. Eye patching was proposed, but the patient strongly declined it due to professional obligations (taxi driver). A custom 18mm soft lens was fitted as a bandage contact lens. The condition improved within days, and the visual acuity returned back to 20/20 in this eye.
Another case that received a lot of attention from the international press, reports of on a large diameter custom soft lens for a 44-year-old elephant in the Dutch zoo Artis. The elephant developed a recurrent corneal erosion according the veterinarian in charge, Mr Verbruggen. To aid healing of the corneal erosion, a large diameter soft lens was placed on the animal's eye. According to the blog (in Dutch), it apparently was not easy to place the lens on the eye, especially since elephants have a third eyelid, which complicated the lens application.
Special Lens Care for
Specialty Soft Lenses
Matt Lampa & Mark André
When the patient's refractive error, corneal shape or irregularity necessitates a custom soft contact lens, frequent disposability of the commodity products is rarely available. Due to the manufacturing costs of these custom lenses, the recommended replacement schedule is often three months or longer. Contemporary multipurpose and hydrogen peroxide systems are intended for contact lenses with a more frequent replacement schedule and usually fall short of properly maintaining lenses for three or more months, and extra care regimens for custom soft lenses may be needed. Through careful material selection, proper care and handling instruction and solution recommendations, we can enhance the performance of custom soft contact lenses for our patients, both immediately and in the long run. Click here for the full report.
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