|Quarterly newsletter on Soft Specialty Contact Lens |
Research, Developments, Designs and Materials SUMMER 2013
|WORLD WIDE VISION
A Statement on
'How to Improve Soft Lens Fitting'
Yes, we fit soft contact lenses in our practice (as they represent more than 90% of the market). And yes, it is an advantage to have disposable lenses. And yes, most disposable lenses fit well. But about a third of all soft lenses fall into the category 'it could fit better.' A wish list can be defined of what we need to better serve our patients in the latter category. A second (smaller) diameter is needed for the currently available disposable lens systems. We know from experience that smaller lenses provide more tear film exchange. This would be better for patients because it may reduce the risk of microbial keratitis. Also, we require more disposable lens systems that offer more than one base curve, especially for toric and multifocal lenses. This is a request and a 'Help' message on how to improve soft contact lens fitting from just one German Educator - but I am not alone! We want to be able to tell our students, practitioners and patients: 'Yes, we can do better. Click here for full report.
Peter Moest PhD
|IN THE LITERATURE|
Developments in Soft Lens Options for Keratoconus
New Lens Design, Materials, Hypoxia
To illustrate the momentum of custom soft lenses in specialty lens practices, Neil Pence in Contact Lens Spectrum describes many new lens designs specifically for keratoconus that have become available to us in recent months. 'The increased comfort and easier adaptation are generally gained at the cost of slightly reduced best visual acuity,' he concludes. On a precautionary note, the author states, 'these are all very thick soft contact lenses,' so despite their availability in high-Dk silicone hydrogel materials, consistant monitoring for hypoxic signs in these patients remains crucial. Photo: Greg DeNaeyer.
|FROM THE WEB|
Myopia Control with Soft Lenses
Children, Myopia Progression Reduction, Safety
Kids & Contact Lenses is the latest special topic on the Contact Lens Update website. Everything regarding children and contact lenses is shared and covered on the site, discussed from different angles and with many authors and researchers involved. An interesting topic - all the more because myopia control with soft lenses is gaining more and more attention and is something that needs to be performed in young children, typically in the 8-12-year age range. The topic of myopia control itself was covered in an earlier edition of Contact Lens Update. Another resource with an enormous amount of information about myopia control and everything related to it is the www.myopiaprevention.org website.
|IN THE LITERATURE|
The Astigmatic Presbyope
Toric, Multifocal, Soft Lenses, Visual Demands
In an online article in Review of Cornea & Contact Lenses, Mile Brujic and Jason Miller focus on 'How to Capitalize on the Astigmatic Presbyope.' The soft multifocal toric market is the newest area of growth, according to the authors. These lenses combine the toric technology used to correct astigmatism with the most advanced soft multifocal lenses. We know that uncorrected astigmatism results in distorted or blurred vision. We also know that there is some loss of visual clarity with soft multifocal contact lenses. If we try to mask uncorrected astigmatism, the overall loss adds up and the success rates decrease. We can help eliminate some of that by first correcting even low amounts of astigmatism. If there is any doubt, correct the cylinder in the phoropter and listen to the response. The fitting process for these lenses is two-fold. First, fit the toric correction and adjust for any rotation or instability. Second, customize the multifocal to the patient's specific visual demands.
|IN THE LITERATURE|
Topographical Changes in Soft Lens Wear
Keratometry, Corneal Topography, Pachymetry
In the series of 'classical papers' regarding soft lens fitting, a paper by Loretta Ng et al is of special interest. The paper looks at candidates for refractive surgery, and how long soft contact lens wearers need to cease lens wear before the cornea becomes stable. 'Stable' is defined as no more than 0.5D of change between consecutive visits. The mean number of days until stability is reached in the soft lens wearers is: 10.7 ± 10.4 days for manifest refraction, 16.2 ± 17.5 days for keratometry and 28.1 ± 17.7 days for topography. It took 35.1 ± 20.8 days for pachymetry (with a criterion of 8 microns) to reach stability. The results illustrate the significant influence that soft lenses can have on corneal topography
. Photo: Vincent Molkenboer
Tinted Lenses & Albinism, Induced Hypoxia, Safety, Microbial Keratitis
A poster by Faheemah Saeed et al at ARVO 2013 (poster #2778) discussed tinted lenses in patients with ocular albinism. Visual acuity, nystagmus intensity and contrast sensitivity with and without glare were significantly improved when patients with albinism wore tinted contact lenses. These effects were maintained or even increased for at least six months following initial dispensing of the tinted lenses, the investigators found. Yichen Sun et al (# 5440) looked at soft bandage contact lens therapy for ocular graft-versus-host disease (GVHD). They concluded that the soft bandage lenses can offer significant symptomatic relief, that ocular coherence tomography can be a feasible method to characterize pathological changes related to ocular GVHD, and that wearing soft bandage contact lenses on an extended wear schedule can diminish the attrition of cornea from eyelid. The evaluation of the effect of soft contact lens edge shape on conjunctival epithelium was the subject of a study by Dorota Szczesna-Iskander and Robert Iskander (# 5482). They concluded that soft contact lens edge shape plays little role in the presumable conjunctival epithelium imprint and suggested that other lens parameters, such as the material properties, may play a more significant role in this phenomenon. Asaki Suzaki et al (#5487) studied the visual performances of a novel silicone hydrogel soft contact lens that was designed to correct a refractive vertical asymmetry in keratoconic eyes. The lens improved the monocular visual performance as well as the degree of vertical coma in eyes with keratoconus
How to Approach a
Soft Lens Fit Post-LASIK
Matt Lampa & Mark André
After LASIK refractive surgery, the resulting corneal profile for patients who were previously myopic is relatively flat centrally versus peripherally (oblate) - the opposite of the normal cornea. This sets up a challenge for contact lens practitioners who wish to appropriately design and prescribe a soft contact lens for such a patient. Utilizing a traditional "off-the-shelf" soft contact lens designed for the prolate cornea on an oblate cornea will cause excessive vaulting of the central cornea. With enough vault, a bubble may form beneath the lens centrally; however, more commonly the patient's vision will simply vary with each blink as the central portion of the lens collapses against the surgically altered central cornea. A simple fitting strategy will help to better align the posterior surface of the contact lens to the cornea
.Click here for the full report on a step-by-step soft lens fitting approach for the post-LASIK patient.
Ocular Surface Shape, Soft Lens Fitting, Myopia Control
The Contact Lens Specialist Symposium 2013 will take place 28th & 29th September 2013 in The Renaissance Hotel, Bath Road, London Heathrow. Keynote speakers will be Pat Caroline, Eef van der Worp and Randy Kojima who will take you on an exciting journey through optics - from understanding the surface of the eye to optimal contact lens fitting. Our Exhibition will guide you through lens choices as well as offer advice on how to build a successful, sustainable business. www.clss.eu
This Newletter is Kindly