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Sunday, February 26, 2012  
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Editor's Commentary - Jason J. Nichols, OD, MPH, PhD, FAAO

Have you given much thought recently to what exactly leads you to make the clinical decisions and establish the prescribing patterns you have? For instance, is there a particular brand of contact lens that is your "go-to" contact lens? If so, why is that the case? How about care solution? Again, why do you use this care solution with most of your patients? There are many factors that might be associated with these decisions including things such as your training, your philosophy about patient care, your belief about the safety or efficacy of the product, or even a business decision. That said, we all tend to be creatures of habit so make sure you don't get stuck in a rut and actively think through each prescription choice you make. Don't be afraid to try new products and rethink conventional wisdom. Your patients may thank you for this.

EyeDock.com Adds GP Lens Search and Refraction Tutorial

EyeDock, LLC, announced the release of its newly redesigned online practitioner reference. After more than a year in development, the revamped EyeDock.com adds a streamlined user login, improved compatibility with mobile devices, a gas permeable lens database of over 1,200 lenses, and an interactive refraction tutorial.

EyeDock.com online clinical reference for eyecare professionals has nearly 3,000 subscribers. The company was founded in 2003 by two optometrists in clinical practice, Todd Zarwell, OD, FAAO, and Brian Chou, OD, FAAO. The website and companion iPhone app offer a searchable contact lens database, clinical calculators, ICD-9 look-up, and ocular pharmaceuticals look-up. The subscription remains free for optometry students and faculty.

Visit www.EyeDock.com to learn more.

Blanchard Introduces Onefit Mini-Scleral Lens

Blanchard Contact Lens launched Onefit P+A (Prolate + Astigmatism), a mini-scleral lens designed to vault over corneas with a normal prolate profile or astigmatism, post grafts (prolate pattern) or moderately irregular corneas such as emergent or fruste keratoconus.

During the development of the lens, Onefit was evaluated on more than 300 patients. According to the company, the final product provides less stress on the cornea, visual acuity and reduced aberrations, accompanied by exceptional comfort and a 3-step, inside-out, fitting approach; making Onefit P+A the easiest mini-scleral lens to fit and trouble shoot.

Onefit P+A is available in diameters of 13.8-14.3mm (standard) / 14.6mm at any power. Fitting sets are available. For additional information, visit www.blanchardlab.com.

Visionary Optics Expands Available Parameters for Hydrokone and RevEyes Lenses

Visionary Optics LLC recently enhanced the design and added to the available parameters for some of their specialty contact lens designs.

The Hydrokone lens now features a redesigned five-curve front surface with extremely high blends and aspheric values and a thinner edge profile for increased patient comfort. The company added 5.1 and 4.9 base curves in their standard Hydrokone design. Additionally 6.0 and 5.7 base curves are now available in the pellucid Hydrokone design for keratoconus.

The RevEyes reverse geometry soft contact lens also has a redesigned, thinner edge profile for extra comfort and 10.3, 10.6 and 11.0 base curves have been added to the line. In addition, the toric haptics (peripheral curve) range has increased in the Jupiter scleral design from 1-4 diopters to 1-7 diopters.

For more information, please visit www.visionary-optics.com.

Vitamin Health Launches Dry Eye Supplement

Vitamin Health, Inc. announced the launch of a new product in their line of Viteyes eye health supplements, Viteyes Dry Eye Formula. Viteyes Dry Eye is formulated to help support dry eye symptoms in only one daily softgel.

The Viteyes Dry Eye formula contains omega-3, flaxseed oil, vitamin E, vitamin B6, lactoferrin and borage seed oil for dry eye relief. It is available in a 3-month supply bottle. Viteyes products can be ordered by phone at 1-800-890-EYES (3937) or online at www.viteyes.com.

Anterior Subcapsular Cataract
By William Townsend, OD, FAAO

The patient in this photo presented with a history of reduced vision in his right eye. His ocular history was significant for trauma; in his occupation as a construction worker he had suffered a blow to the right eye with the end of a board. Since that accident, he experienced slowly progressive reduction in vision in the affected eye.

One segment of the Beaver Dam Study sought "to describe the long-term incidence of nuclear cataract, cortical cataract, and posterior subcapsular cataract (PSC) and to evaluate age and cohort effects on these rates." The researchers evaluated 5,925 eligible individuals ages 43 to 84 years old for the presence of cataracts or a history of cataract surgery. Notably absent from this study is anterior subcapsular cataracts (ASCs), which is the condition pictured here.1

A Korean study of 13,029 eyes that had undergone cataract surgery found that ASC accounted for only 4.8 percent of cases.2

For more on ASCs, see http://www.clspectrum.com/articleviewer.aspx?articleID=104871.

We welcome photo submissions from our readers! It is easy to submit a photo for consideration for publishing in Contact Lenses Today. Simply visit http://www.cltoday.com/upload/upload.aspx to upload your image. Please include an explanation of the photo and your full name, degree or title and city/state/country.

1. Klein BE, Klein R, Lee KE, Gangnon RE. Incidence of age-related cataract over a 15-year interval the Beaver Dam Eye Study. Ophthalmology. 2008 Mar;115(3):477-82.
2. Kim H, Park JW, and Joo CK. Prevalence and Risk Factors of Anterior Subcapsular Cataract in a Hospital–Based Case–Control Study. Invest Ophthalmol Vis Sci 2004;45: E-Abstract 3749.

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Ronald K. Watanabe, OD, FAAO

GSLS Report

This week's column was submitted by my two residents in Cornea and Contact Lenses, Dr. Yin-Yin Aung and Dr. Rutvi Doshi, who report on some of the interesting topics of last month's Global Specialty Lens Symposium.

Several new large diameter GP lens designs were discussed, which provide additional options for fitting the irregular cornea (some, but not all, of which are mentioned here). With increasing knowledge in scleral lens fitting techniques, manufacturers are placing more emphasis on corneal and scleral shape variability for initial lens selection. Anterior segment optical coherence tomography (OCT) is being used more often to determine an accurate measurement of the corneal sagittal depth as well the fluid layer thickness under the lens.

The new Onefit P+A Series (Blanchard Contact Lens) is designed to vault over normal or mildly irregular corneas while providing good peripheral alignment over the sclera. OCT can be used to visualize the fitting relationship and make modifications to the corneal and/or scleral zones. The Irregular Corneal Design (ICD 16.5, Valley Contax) is another new mini-scleral design that utilizes OCT, a sagittal depth calculator or trial lens fitting to determine the sagittal height for initial lens selection. The overall goal of these designs is to promote ease of fitting. These and other new options add to the growing list of excellent scleral lens designs—stay tuned for more information on other lens options in future columns.
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Brien Holden, PhD, DSc, OAM, FAAO

Have Bugs Killed EW? Will SiHy DD Help?

Swept up in the euphoria of the development of silicone hydrogel contact lenses in the great collaboration between CIBA Geigy, CIBA Vision and CRCERT (the three Cs or SEE3 Project) from 1992 to 2000 that produced silicone hydrogel lenses, we had hoped that a healthier epithelium would reduce serious infections. We weren't naive — we knew that silicone elastomer lens MK cases occurred [1] — proving that no matter how much oxygen was supplied, bugs could win with an overwhelming inoculation, but it was disappointing that the outcome of oxygen permeable contact lenses was not less frequent MK. Fiona Stapleton and colleague's evidence [2-4] suggests that SiHy MK cases are less severe and resolve more quickly with High Dk/t lenses — but are no less frequent.

Extended wear research has virtually stopped except for an intrepid few at BHVI and LVPEI including Jerome Ozkan who are testing the effect on adverse events of morning and nightly removal, and even daily disposal of extended wear, and antibiotics with EW contact lenses on a surrogate for MK [5-8]. It appears that morning removal does reduce the risk compared with overnight replacement, so that getting rid of overnight 'accumulations' helps more than a clean lens at night. Handling lenses in the evening appears to overwhelm the benefit offered by replacing lenses. If we had done that research in the late 90s — maybe EW would have worked out differently.

The Jury is out on other strategies to reduce infection such anti-microbial lenses, but for daily wear, anti-microbial cases have been shown to lower the level of bacterial challenge [9]. Though anti-microbial lenses might reduce the risk of MK slightly (almost impossible to prove in clinical studies) it is unlikely they could cope with the millions of microbes to which people expose their lenses from time to time.

This whole area is liable to receive a considerable deal of attention now that silicone hydrogel daily disposable lenses are starting to appear. There have been a few stumbles on their way, but it will be interesting to see whether studies of sufficient size and integrity are done to establish the 'real' performance of DDEW.

[1] Holden BA, Sweeney DF, Sankaridurg PR et al. Microbial keratitis and vision loss with contact lenses. Eye Contact Lens 2003; 29:S131-134; discussion S143-134, S192-134.
[2] Stapleton F, Stretton S, Papas E et al. Silicone hydrogel contact lenses and the ocular surface. Ocul Surf 2006; 4:24-43.
[3] Stapleton F, Keay L, Edwards K et al. The incidence of contact lens-related microbial keratitis in Australia. Ophthalmology 2008; 115:1655-1662.
[4] Keay L, Edwards K, Stapleton F. An early assessment of silicone hydrogel safety: pearls and pitfalls, and current status. Eye Contact Lens 2007; 33:358-361; discussion 362-353.
[5] Ozkan J, Zhu H, Gabriel M et al. Effect of prophylactic antibiotic drops on ocular microbiota and physiology during silicone hydrogel lens wear [published online ahead of print January 12 2012]. Optom Vis Sci 2012: http://www.ncbi.nlm.nih.gov/pubmed/22246331. Accessed February 10, 2012.
[6] Ozkan J, Mandathara P, Krishna P et al. Risk factors for corneal inflammatory and mechanical events with extended wear silicone hydrogel contact lenses. Optom Vis Sci 2010; 87:847-853.
[7] Ozkan J, Zhu H, Gabriel M et al. Daily instillation of antibiotic drops during continuous wear of silicone hydrogel lenses. ARVO. Fort Lauderdale, FL, USA: 2010; 51:1515
[8] Ozkan J, Willcox M, Lazon de la Jara P et al. Morning cleaning or replacement of lenses reduces complications with extended wear of contact lenses. ARVO. Fort Lauderdale, FL, USA: 2012. Accepted.
[9] Dantam J, Zhu H, Stapleton F. Biocidal efficacy of silver-impregnated contact lens storage cases in vitro. Invest Ophth & Vis Sci 2011;52:51-7.

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Loretta B. Szczotka-Flynn, OD, PhD, MS, FAAO

More on Keratoconus and Aberrations

Higher-order aberrations and scatter are two optical phenomena which are difficult to separate, nonetheless Jinabhai and coworkers feel they can utilize a straylight meter to isolate the effects of intraocular light scatter in keratoconus patients (the instrument they use is relatively robust to refractive errors in keratoconus patients with good best corrected acuity). They found that intraocular light scatter was significantly greater in five keratoconic patients than in normal subjects for three eccentricities tested. Contrast sensitivity was also found to be lower in the keratoconus group, which was negatively correlated with intraocular straylight. They conclude that high values of straylight measured in the keratoconic patients are not explained by age or scarring and could be related to the structural degradation of the cornea. As the possibility of customized aberration-controlling contact lenses becomes a reality, an understanding of how the keratoconic eye scatters light assists in the understanding of limits to visual improvement achieved by successfully correcting higher-order aberrations alone.

Look for another paper from this group on "Changes in Refraction, Ocular Aberrations, and Corneal Structure After Suspending Rigid Gas-Permeable Contact Lens Wear in Keratoconus" to be published later this year in the Cornea journal. The abstract is featured below in this issue of Contact Lenses Today.

Jinabhai A, O'Donnell C, Radhakrishnan H, Nourrit V. Forward light scatter and contrast sensitivity in keratoconic patients. Cont Lens Anterior Eye. 2012 Feb;35(1):22-7.
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Changes in Refraction, Ocular Aberrations, and Corneal Structure After Suspending GP Wear in Keratoconus

This study reports on changes in visual acuity, ocular higher-order aberrations, and refraction after suspending rigid gas-permeable lens wear for 1 week in 15 patients with moderate to severe keratoconus. Alterations in the anterior surface, central corneal powers and axes, and central corneal thickness were also explored.

Scheimpflug photography and Hartmann-Shack aberrometry were performed at two visits, 7 days apart, after the patients had removed their habitual contact lenses. Subjective refraction and both high- and low-contrast logarithm of the minimum angle of resolution visual acuities were also recorded at both visits.

Reductions in both high-contrast visual acuity (P = 0.001) and low-contrast visual acuity (P = 0.002), along with an increase in third-order root mean square aberrations (P = 0.008), occurred after rigid gas-permeable lens wear was suspended in these patients with keratoconus. However, no significant changes in subjective refraction were found over the 1-week period (P >/= 0.10). Significant correlations were observed between third-order coma root mean square aberrations and the measured high-contrast (rp >/= 0.59; P </= 0.02) and low-contrast visual acuities (rP >/= 0.61; P </= 0.015). In addition to increases in the anterior surface central corneal powers (P </= 0.02), a reduction in central corneal thickness also was found between the two visits (P = 0.00016).

The authors concluded that changes in the optical and structural parameters of the keratoconic cornea occur after suspending rigid gas-permeable contact lens wear. This information may be of interest to practitioners concerned with prescribing aberration-controlling soft contact lenses for such patients.

Jinabhai A, O'Donnell C, Radhakrishnan H. Changes in Refraction, Ocular Aberrations, and Corneal Structure After Suspending Rigid Gas-Permeable Contact Lens Wear in Keratoconus. Cornea. 2012 Feb 6. [Epub ahead of print]
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