Official Site of Silicone Hydrogel Lenses http://www.siliconehydrogels.org/ http://blogs.law.harvard.edu/tech/rss Tue, 10 Nov 2009 09:34:38 +1100 Tue, 10 Nov 2009 09:32:57 +1100 FeedForAll v2.0 (2.0.2.9) http://www.feedforall.com http://www.siliconehydrogels.org/images/editorial/logo_feature_review.jpg http://www.siliconehydrogels.org/ Contact Lens 155 120 Introduced simply as Peanut Butter Cups, and now known as Reese’s Peanut Butter Cups (Hershey Foods Corporation, Hershey, PA), this combination of chocolate and peanut butter has been manufactured for over 80 years. For many years the advertising campaign for this product revolved around the concept of two great tastes that taste great together. Unless you are an extreme chocolate connoisseur, although a bit unconventional, one could consider the combination of lens material and lens optics introduced in today’s silicone hydrogel multifocal lenses an equally impressive feat, with two rather impressive lens developments that have the potential to work great together to improve comfort and vision for presbyopic contact lens wearers (and chocolate lovers, alike). http://www.siliconehydrogels.org/editorials/index.asp 3E41B547-6CC5-4E65-BE28-8DB5EC048986 Tue, 10 Nov 2009 09:32:57 +1100 The generation of presbyopes now emerging, a group commonly classified as ‘Generation X’, have adapted to the inception of many new technologies during their lives: Home computers, video games, the Internet, email, mobile phones, laptops, and GPS are routinely used today, both socially and in business. Now, some early presbyopic ‘Gen Xers’ have started to notice texting becoming difficult or that the font size on the laptop is not large enough and their habitual near tasks are becoming visually challenging. http://www.siliconehydrogels.org/in_the_practice/index.asp 91B673B4-B47B-4730-BFA5-5B97B3E7D77B Tue, 10 Nov 2009 09:32:00 +1100 To determine and generate oxygen transmissibility (Dk/t) profile maps across various contact lenses in different powers. http://www.siliconehydrogels.org/posters/latest.asp CF48536F-817B-4BA4-A5A6-20EED48D8809 Tue, 10 Nov 2009 09:31:35 +1100 Jason Nichols (The Ohio State University, USA) and Philip Morgan (Eurolens Research, The University of Manchester, UK) provided an overview of the 2009 contact lens market in the USA. Results of an annual survey indicate that silicone hydrogel lenses account for 54% of fits in the United States. Soft toric lenses account for 22% of fits, 30% of which are silicone hydrogel toric lenses. In the United States, silicone hydrogels are the most commonly prescribed material for new soft fits, compared to worldwide trends indicating that most patients are still wearing conventional soft lenses (49%) for daily wear, instead of silicone hydrogels (18%). Silicone hydrogel daily wear accounts for 22% of fits in the UK, 15% in Japan, 23% in the Netherlands, 8% in Hong Kong, and 36% of fits in Australia. http://www.siliconehydrogels.org/meeting_synopsis/index.asp 5A68179C-0E8F-44EE-BA3A-AB048A428314 Tue, 10 Nov 2009 09:31:10 +1100 When visiting the optometrist or ophthalmologist, a patient will encounter the process of refraction. A distance prescription derived from refraction is designed to correct two types of refractive errors: spherical and cylindrical errors. But what if the refractive error of the eye is not well characterized by sphere and cylinder alone? One subset of individuals whose visually significant refractive error is often more complex than traditional sphere and cylinder is found in patients with keratoconus. http://www.siliconehydrogels.org/editorials/index.asp 2D3F200D-1C31-4558-9193-3CBC096AD0BA Tue, 22 Sep 2009 10:16:46 +1000 Soft lenses that correct keratoconus have been available for around 13 years in hydrogel form. Although they work well, there has always been concern about possible vascularisation (as with Hybrid lenses) if lenses are worn for long periods of time. With the advent of lathe cut silicone hydrogel materials, these lens types now allow up to even 18 hours comfortable, healthy wear. This is extremely important to keratoconics, as they are reliant on their lenses for functional vision. Many question how a soft lens can correct anything other than mild to moderate keratoconus – surely the lens simply reproduces the corneal irregularity? http://www.siliconehydrogels.org/in_the_practice/index.asp 258CA2C3-A6AF-4806-8714-7865EA081ADF Tue, 22 Sep 2009 10:16:17 +1000 Discomfort, dryness, redness, poor vision and shorter wear time are associated with drop out from low Dk soft lens daily wear (Pritchard et al 1999, Young et al 2002). Refitting with silicone hydrogel lens can alleviate some of these problems (Riley et al 2006, Dumbleton et al 2006). However, drop out from silicone hydrogel lens wear still occurs so we investigated to see if the same factors were leading to discontinutation in silicone hydrogel lens daily wear (SiHy DW). http://www.siliconehydrogels.org/posters/latest.asp F21B787B-1083-428A-8A7D-96A26955F279 Tue, 22 Sep 2009 10:13:58 +1000 Mark Willcox and colleagues (Institute for Eye Research and School of Optometry and Vision Science UNSW, Molecular and Health Technologies, CSIRO, Australia) reported that lotrafilcon B and galyfilcon A lenses produced corneal staining (but no redness) after soaking in a PHMB-based lens care system. Compared to lenses inserted directly from the blister pack, the lotrafilcon A lenses were less comfortable and produced an increase in burning/stinging after soaking in the PHMB-based solution; the same lenses were associated with an increase in lens awareness and itchiness after soaking in a polyquad-based system. http://www.siliconehydrogels.org/meeting_synopsis/index.asp 1999146E-515E-4FFB-B59D-3EF22F7E0E8E Tue, 22 Sep 2009 10:12:28 +1000 With this year marking the tenth anniversary of the introduction of silicone hydrogel lenses on the worldwide market, it is interesting to reflect on the differences we have seen in utilization patterns and growth in this material’s market share worldwide. The most accessible place to find that information is the International Contact Lens Prescribing Survey, a yearly, multi-country, collaborative project headed by Dr Philip Morgan, Director of Eurolens Research (Manchester, UK) with help from researchers around the globe. Most recently, this team reported on data from the 2008 survey (Morgan et al. 2009), which included 27 different countries. http://www.siliconehydrogels.org/editorials/index.asp D18B4ADF-500A-4850-851B-4A0333AA7DC3 Tue, 16 Jun 2009 09:48:04 +1000 A 48 YO Female wanted to be fit with contact lenses, specifically a contact lens that would help reading with her left eye. Her ocular history included high myopia with reduced vision OD secondary to posterior staphyloma. The patient also wanted to be able to best use the available vision in her right eye. She was wearing a soft contact lens with unknown parameters in the left eye for distance only. http://www.siliconehydrogels.org/in_the_practice/index.asp 01EB1FF2-8ED9-4F6A-9D3D-DC1BE5882166 Tue, 16 Jun 2009 09:47:39 +1000 Silicone hydrogel contact lenses (CLs) are becoming increasingly popular for daily and overnight wear, due to their higher oxygen transmissibility compared to hydrogel CLs. The aim of this study was to investigate the clinical and subjective performance of lotrafilcon A upgrade (CIBA Vision), which includes a visibility tint, inversion indicator and a comfort additive in the package saline, during extended wear (EW)/flexible wear (FW). http://www.siliconehydrogels.org/posters/latest.asp C48227ED-1F64-4FF6-955B-AD8FE1FFF852 Tue, 16 Jun 2009 09:47:18 +1000 Researchers at the Centre for Contact Lens Research (University of Waterloo, Canada) demonstrated the physiological benefit of refitting conventional hydrogel wearers with silicone hydrogel lenses by using Adobe Photoshop to manipulate and analyze the images. Jill Woods and colleagues refit highly myopic hydrogel wearers with a lathe-cut sifilcon A lens, which was worn on a daily wear basis for 9 months. Photographs were taken of the superior, inferior, temporal and nasal limbal regions, at 12x magnification and then imported into Adobe Photoshop, where a red-free filter was applied to enhance contrast. They then measured the length of the longest visible blood column and counted the number of blood columns measuring over 0.5 mm in each quadrant. http://www.siliconehydrogels.org/meeting_synopsis/index.asp BF0E794D-2C7C-4603-807F-5B9090D288B1 Tue, 16 Jun 2009 09:46:50 +1000 One of the major breakthroughs in the development of silicone hydrogel (SH) contact lenses has related to the ability of manufacturers to overcome the surface hydrophobicity that occurred with silicone elastomer lenses. This has been accomplished by various techniques, including the incorporation of plasma into the surface processing and internal wetting agents. http://www.siliconehydrogels.org/editorials/index.asp E80B7B6A-A5E0-4563-8402-FDD4256882A8 Mon, 18 May 2009 10:18:36 +1000 A Caucasian female, age 46, was referred to the Clinique Universitaire de la Vision (University of Montreal) for corneal topography measurements. The referring optometrist suspected corneal warpage secondary to continuous wear of Focus Night and Day contact lenses. The patient had ceased to wear her contact lenses 3 weeks prior to the visit, complying with the recommendation of her optometrist. http://www.siliconehydrogels.org/in_the_practice/index.asp 453B3037-D03D-4351-AAA8-DB32D59D14CC Mon, 18 May 2009 10:18:11 +1000 To report the symptoms and experiences associated with habitual hydrogel (Hyd) and silicone hydrogel (SiHy) contact lenses (CLs) among young adults and measure their association with age between 18 and 35 years of age. Questionnaire responses from 699 Hyd and 183 SiHy wearers were analyzed to test the association of age with features that indicate struggle with CL wear. http://www.siliconehydrogels.org/posters/latest.asp B373CED1-07A7-44E4-B1C8-275D9B1AB868 Mon, 18 May 2009 10:17:46 +1000 Finding objective and repeatable measures to identify and address the mechanism behind the reduction in comfort with lens wear has presented an ongoing challenge to contact lens researchers. Contact lens wearers tell us they are not happy with lens wear by the end of the day, but without objective measures to assess the impact of the lens materials on the ocular surface, and in particular the tear film, the mechanisms underlying these symptoms are hard to pin down. http://www.siliconehydrogels.org/featured_review/index.asp 576DDC1E-A173-4C78-84C3-B521DC8D1B3E Mon, 18 May 2009 10:17:27 +1000 In May 2007 Advance Medical Optics recalled their multipurpose disinfecting solution (MDPS) named Complete MoisturePlus from sale after it was found that use of this solution resulted in a 7-17% increased risk of developing Acanthamoeba keratitis (Joslin et al., 2007; Bryant et al., 2007). During the licensing of MPDS for sale in most countries, companies are required to test the MPDS by using a variety of techniques to ensure there is a minimum level of disinfecting activity. http://www.siliconehydrogels.org/editorials/index.asp 0829DE83-D70F-4A36-9A13-595195FA8434 Mon, 2 Mar 2009 09:28:25 +1100 Using the sessile drop method of measuring contact angle, Walter Nash and colleagues (CIBA Vision) found that surface-treated lotrafilcon B lenses direct from a packaging solution containing a comfort additive exhibited lower advancing contact angles than lenses made from lotrafilcon A and B, balafilcon A, comfilcon A, galyfilcon A and senofilcon A, also direct from packaging solution. (123) http://www.siliconehydrogels.org/meeting_synopsis/index.asp 1433494A-F6A7-47BF-B2A0-92F07C61FFFE Mon, 2 Mar 2009 09:27:43 +1100 To investigate the clinical performance of a peroxide-based care system (CIBA Vision ClearCare - CC) and a multi-purpose lens care system formulated for use with silicone hydrogels (Alcon Opti-Free RepleniSH - OFR), when used with two silicone hydrogel lens materials. http://www.siliconehydrogels.org/posters/latest.asp 5EC892E2-F327-4756-8EED-FC85D82E3685 Mon, 2 Mar 2009 09:27:01 +1100 The masking of both regular and irregular astigmatism has been attempted with the use of spherical soft contact lenses. There have been reports that aspheric front surface lenses aid in the correction of small amounts of astigmatism, although others indicate that they do not. Still others report that small amounts of astigmatism are not sufficiently masked by spherical lenses and that toric lenses are required. http://www.siliconehydrogels.org/editorials/index.asp C1ADA6F4-708E-4AF0-A7F3-B4CA10267B94 Mon, 15 Dec 2008 09:34:16 +1100 A 34-year-old female patient (JG) was referred to the author for contact lens fitting in 1997. History revealed the patient to have undergone bilateral radial keratotomy (RK) approximately nine years earlier to reduce a relatively high degree (between 5 and 6 D) of myopia in both eyes. Unfortunately, the patient experienced a significant hyperopic shift in both eyes post-RK. In addition, the post surgical corneal contour was now markedly irregular, resulting in a decrease in the quality of vision experienced by the patient. http://www.siliconehydrogels.org/in_the_practice/index.asp 43DE92B4-11FD-40C6-9F28-3B7DF6159686 Mon, 15 Dec 2008 09:33:51 +1100 To compare the kinetics of lactoferrin deposition on silicone hydrogel (SH) and FDA group II (GpII) and group IV (GpIV) conventional hydrogel contact lens materials by artificially doping lenses with labeled lactoferrin solution http://www.siliconehydrogels.org/posters/latest.asp 1A2C9C7A-9471-4893-863A-0792DEAC60E9 Mon, 15 Dec 2008 09:28:27 +1100 A recent study conducted by the Institute for Eye Research (IER, Australia) revealed unique ocular staining with different solution-lens combinations: Hydrogel peroxide causes almost no staining. This group has developed a matrix in the hopes of minimizing SICS by helping practitioners choose the best combination of lens and solution for each patient. http://www.siliconehydrogels.org/featured_review/index.asp 1C28F0AC-9C3F-4590-82B5-623BE2880BEA Mon, 15 Dec 2008 09:27:49 +1100 What do your patients talk about after they leave your consulting room? One way to find out is to lurk on the many internet chat sites devoted to health and health related issues. Several of these have contact lens threads, the content of which can be either interesting or frightening, depending on your disposition. A lively topic recently has been that of silicone allergy, with many contributors apparently convinced that this is the reason for their red eyes, discomfort, itchiness, etc., etc. Interestingly, some appear to have had this suspicion confirmed by their eye care practitioner, which of course, lends legitimacy to the condition in the eyes of many (pun intended), and belief in silicone allergy does exist among contact lens professionals. http://www.siliconehydrogels.org/editorials/index.asp 12FBE181-7755-432D-A483-13F097655097 Thu, 16 Oct 2008 14:55:19 +1100 To determine the ocular response associated with a silicone hydrogel lens and two marketed multi-purpose solutions (MPS) based on comfort and corneal staining after 2 hrs of lens wear at multiple study sites. http://www.siliconehydrogels.org/posters/latest.asp 80AADF6C-3FF0-4DE5-974C-A7E0CE27CCEE Thu, 16 Oct 2008 14:54:36 +1100 Everyday I am grateful for the advances in contact lens technology such as silicone hydrogel designs, which have enabled me to successfully fit more patients with contact lenses. Beside the significant benefit of the high Dk/t removing the risk of hypoxia to the cornea, silicone hydrogels also offer greater biocompatibility for lens wearers who work long hours in low humidity air conditioning, presumably due to the lower water content dependent and more lubricating surface properties of the polymers. A large percentage of my borderline dry eye patients who struggled to maintain a comfortable and useful daily wear time with their soft lenses are happy converts to silicone hydrogels. http://www.siliconehydrogels.org/in_the_practice/index.asp 62581515-FB35-4855-8AB2-E6A488AFD799 Thu, 16 Oct 2008 14:53:54 +1100 D. Willcox and colleagues (Institute for Eye Research, Australia) indentified 68 different proteins deposited on silicone hydrogel contact lenses during one month of daily wear. They found that senofilcon A (with PHMB solution) had adsorbed the highest number of protein species while protein samples from lotrafilcon B (with peroxide) and galyfilcon A (with polyquad) had the lowest number. http://www.siliconehydrogels.org/meeting_synopsis/index.asp B037793A-55C2-4DE8-9778-D6F7882C0392 Thu, 16 Oct 2008 14:52:58 +1100 Contact lenses worn on a daily wear schedule need to be stored overnight, and they must be stored in a solution that disinfects the lenses to remove colonising microbes from the lens surface resulting in a non-contaminated lens to be worn on the following day. In addition to disinfecting the lenses overnight, solutions also clean lenses of contaminating tear film components (proteins/lipids) from the lens surface. http://www.siliconehydrogels.org/editorials/index.asp AC05D356-6D54-46E1-ADBB-673949803DF4 Wed, 27 Aug 2008 09:56:58 +1000 This patient has slight hayfever currently. She is wearing the lens for six nights a week on an extended wear. Her driving has increased from 6,000 miles per year to 9,000. She uses wetting drops on waking. The lens rotates 15 degrees temporally and is stable. She is able to use her binocular stereopsis on the microscope at work when screening for breast cancer. http://www.siliconehydrogels.org/in_the_practice/index.asp 8FC08088-33B9-45C6-A425-12EF3E9CBC37 Wed, 27 Aug 2008 09:56:35 +1000 Previous work has shown that 1 day of overnight wear of HEMA and silicon-hydrogel lens wear causes significant changes to epithelial barrier function (EBF). This current study explores the effects of 30-day continuous wear (CW) of gas-permeable (GP) and silicone hydrogel (Si-H) lenses on EBF. http://www.siliconehydrogels.org/posters/latest.asp A61087B3-13F4-438A-A43A-6E7643A0B0FD Wed, 27 Aug 2008 09:56:07 +1000 The Acanthamoeba parasite can cause some of the more tissue destructive cases of keratitis. It has the ability to adhere to soft contact lenses and in the presence of an epithelial break it can quickly attack the host cornea. Early intervention with appropriate treatment improves the outcome of this infection and may prevent the need for corneal transplant but accurate diagnosis is frequently complex and therefore appropriate treatment can often be delayed in Acanthamoeba infections. http://www.siliconehydrogels.org/featured_review/index.asp AFF787B3-6C61-42A5-8F3F-69EF8B4C396F Wed, 27 Aug 2008 09:55:25 +1000 Purpose: To evaluate the contact lens fitting preferences of Canadian optometrists over the period 2000 – 2006, to determine the trends in fitting that occur as new lens types and modalities are released into the market. Methods: 1000 Canadian optometrists were surveyed annually over a 7 year period (2000-2006), resulting in 7000 optometrists in total being surveyed. Surveys requested information about the next 10 patients fit with contact lenses and which contact lens solutions were dispensed. http://www.siliconehydrogels.org/posters/latest.asp A04A2E32-49AF-443F-B2F0-C2CFE49F7D0C Mon, 14 Jul 2008 09:08:06 +1000 Imagine you have a happy, compliant patient. They have worn contact lenses for many years. Very few complications. They also have glasses that they are happy to wear, doing so at least one day per week and at the end of each day before they go to bed. The corneas are normal – tear film, epithelium and endothelium look good. There is a little bit of limbal injection but nothing clinically significant. The upper lids are smooth. The patient even reports, when asked, that their lenses are comfortable. http://www.siliconehydrogels.org/in_the_practice/index.asp B74B0028-F8CF-4D4C-94B1-037BFE0D9DDA Mon, 14 Jul 2008 09:08:06 +1000 As we rapidly approach the tenth anniversary of the introduction of silicone hydrogel lens materials, it is apparent from both clinical experience and information obtained from many controlled scientific studies that such materials provide huge benefits to our patients. Hypoxic issues such as epithelial microcysts, stromal striae, endothelial polymegethism, limbal hyperemia, neovascularisation and myopic creep are all markedly reduced or reversed with these materials. http://www.siliconehydrogels.org/editorials/index.asp B74A20C2-E6A3-4E76-9EC7-DB7A40ABEE13 Mon, 14 Jul 2008 09:08:06 +1000 In 2007, two new lens types were introduced into the silicone hydrogel contact lens market, Biofinity (comfilcon A, CooperVision, Inc) and PremiO (asmofilcon A, Menicon). More recently Avaira (enfilcon A, CooperVision, Inc) has been released. These are the first entries onto the silicone hydrogel market for Menicon, a company synonymous with high oxygen gas permeable lenses, and CooperVision, whose Proclear soft disposable product continues to do well in an ever increasing silicone hydrogel daily wear market. http://www.siliconehydrogels.org/editorials/index.asp 999415AE-D641-4F63-BEFE-DA7AE2330466 Fri, 6 Jun 2008 15:56:07 +1000 The staining that occurs with certain combinations of silicone hydrogel materials and multipurpose solutions continues to be explored worldwide. Gary Andrasko (private practitioner) and Kelly Ryen reported that excessive corneal staining was more likely to occur with PHMB-based solutions than with hydrogel peroxide or polyquad. Surface-treated silicone hydrogel materials tended to induce the greatest staining area. Comfort consistently decreased when average staining area was greater than 30%, and reached a peak early in the lens wearing day. Christine Sindt and colleagues (University of Iowa) reported that staining associated with balafilcon A lenses was more clinically significant and covered a wider area when subjects used a PHMB-based solution. Subjects using this solution also reported a significant drop in comfort. http://www.siliconehydrogels.org/meeting_synopsis/index.asp 28FFC0E7-A93E-44B0-A437-D878EC575343 Fri, 6 Jun 2008 15:55:38 +1000 Purpose: To determine corneal oxygen consumption with different silicone hydrogel lenses under open and closed eye conditions. Methods: Human eye models were used to assess the relationship between Equivalent Oxygen Percentage (EOP) and lens oxygen transmissibility (Dk/t) with four different silicone hydrogel lenses (Focus NIGHT & DAY, O2Optix, PureVision and Acuvue Advance) in two powers (-3.00DS and +6.00DS) and one conventional thick soft lens (CIBASoft) in one power (+6.00DS). http://www.siliconehydrogels.org/posters/latest.asp F3C18DA0-1119-4371-B254-784D4CF8F582 Fri, 6 Jun 2008 15:55:16 +1000 This routine fitting of a low myope highlights some aspects of silicon hydrogel lenses (SiHy) which sometimes makes them a little unpredictable. Like a lot of practitioners, I have found SiHy lenses to be invaluable in high ametropia, astigmatism and problem solving. I feed off patient’s enthusiasm when patients report better wearing times and whiter eyes. Not surpringly, SiHy lenses have become my lenses of first choice; but they are stiffer and have novel surfaces, and consequently do not always behave in a predictable way. This recent fitting of a neophyte illustrates this. http://www.siliconehydrogels.org/in_the_practice/index.asp 3EA71B8D-9BCD-4F9C-ACB1-529B1FE8651E Fri, 6 Jun 2008 15:54:37 +1000 A slitlamp examination of a patient complaining of sore, red eyes and variable vision uncovered multiple contact lens related conditions. ­Although overwear of contact lenses is a contributing factor in this case, it is not a diagnosis in itself. A 35-year-old male presented on referral from a local optometrist. He reported sore, red eyes and variable vision for the previous two months and was wearing hydrogel contact lenses that had been prescribed in the United Kingdom about one year before. He was wearing the contact lenses all waking hours but denied sleeping in them. http://www.siliconehydrogels.org/in_the_practice/index.asp D118E178-231A-4C2E-9243-2DCE626ACBAF Wed, 30 Apr 2008 11:47:30 +1000 Purpose: To compare the saturation of silicone hydrogel contact lenses in the Indiana University School of Optometry (IUSO) clinic system from the same quarter 2005 and 2006 to determine the growth of this lens material over time. Methods: Data of all soft contact lens supply orders in IUSO clinics from the 1st Quarter (1stQ) of both 2005 and 2006 was compiled. The total number of orders placed for all soft contact lens materials was compared with the orders for silicone hydrogel materials and those orders were then examined by lens design. http://www.siliconehydrogels.org/posters/latest.asp F0FF518D-5590-4A78-B85D-7FB3F49BB1AB Wed, 30 Apr 2008 11:47:31 +1000 This first synopsis of the 2007 AAO meeting summarizes papers and presentations on the physiological effects of silicone hydrogel lenses, as well as case reports relating to the use of silicone hydrogel lenses for therapeutic needs. During a course of treatment with therapeutic contact lenses, it may be necessary to measure intraocular pressure without removing the patient’s contact lens. Muriel Schornack and Melissa Rice (Mayo Clinic) compared intraocular pressure measurements through a galyfilcon A contact lens to measurements made with no lens in place. http://www.siliconehydrogels.org/meeting_synopsis/index.asp 52A4540C-70D6-4152-947B-8636CE89E6AA Wed, 30 Apr 2008 11:47:32 +1000