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International Newsletter and Forum on Rigid Gas Permeable Contact Lenses, Corneal Shape, Health and Vision |
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Scleral Lens Nomenclature
 After carefully considering input from a number of sources, the Scleral Lens Education Society (SLS) recommends internationally recognized nomenclature for scleral lenses according to size and fit characteristics. This is a difficult task due to the large number of naming schemes by individuals, manufacturers and distributors. The goals are to simplify and generalize the nomenclature. According to the SLS recommendations, the bearing of the lens is the defining feature in scleral lens terminology. Simply put, if a lens rests completely on the cornea, it is called a corneal lens. A lens that partly rests on the cornea (centrally or peripherally) and partly on the sclera is called a corneo-scleral lens. A lens that rests entirely on the sclera is a scleral lens no matter how large that lens is. Scleral lens designs that are relatively small in diameter but rest entirely on the sclera are thus referred to as 'scleral lenses,' while a corneo-scleral lens with the same overall diameter as the scleral lens described is, indeed, a corneo-scleral lens. When there is full bearing on the sclera, further distinctions of the scleral lens group include mini-scleral and large-scleral lenses. See the full scheme and description via the link above, and at the SLS website www.sclerallens.org. Eef van der Worp |
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Keratoconus
The most downloaded article by far in Contact Lens & Anterior Eye (journal of the BCLA) over 2012 was an article by Romero-Jimenez, Santadomingo-Rubido and Wolffsohn: Keratoconus - a review, which was downloaded 1,740 times (the article was the most cited as well). Keratoconus gets a fair amount of attention in the various journals. In May's Optometry & Vision Science, the question was raised: Is Consanguinity a Risk Factor for Keratoconus? The study supports the hypothesis that consanguinity is indeed a significant risk factor for keratoconus and provides strong support for a genetic contribution to the disease. Wearing sunglasses in this environment is beneficial, and the study confirmed that eye rubbing, allergy and education are also significantly associated with keratoconus after adjusting for other predictors. Also in Contact Lens & Anterior Eye, a study was performed looking at endothelial cell density of keratoconic eyes with no history of contact lens wear, versus healthy non-keratoconic subjects. Endothelial cell density was unaltered in keratoconic patients without a history of contact lens use when compared with the healthy controls.
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Let the Wavefront Guide
Wavefront -guided scleral lens prosthetic devices for keratonus is the topic of a paper in the April issue of Optometry & Vision Science. The authors show that the root mean square with the wavefront-guided lenses was reduced 3.1 times, resulting in a significant improvement of 1.9 lines in mean visual acuity. Contrast sensitivity was also significantly improved. The aberrations of the eye were measured while wearing a scleral prosthetic device with conventional spherical optics. The position of the lens on the eye was noted and incorporated in the final lens design to apply the wavefront-guided optics.
Sabesan et al - Optometry & Vision Science, April 2013
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Vision-Related Quality of Life
The
aim of this study was to compare vision-related quality-of-life in children wearing orthokeratology lenses with children wearing single-vision spectacles. Thirty-one children were fitted with orthokeratology, 30 with spectacles. Children wearing orthokeratology contact lenses rated overall vision, distance vision, symptoms, appearance, satisfaction, activities, academic performance, handling, peer perceptions, and the overall score significantly better compared to children wearing spectacles (all P<0.05). Near vision and handling were, respectively, rated better (P<0.001) and similar (P=0.44).
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Intense
 Objective quantification of fluorescein intensity on the corneal surface is the subject of a paper by Tan et al. in Eye & Contact Lens. The paper looks at fluorescence intensity, use of external light sources and filters. A 'step-by-step' improvement in the quality of the corneal fluorescence image was achieved by combining external flash, incorporating filters & diffusers and increasing the working distance. In the same edition of the journal, a paper by Ye et al. looks at slit-lamp photography using various camaras. One option is using smart phones, with apparently good results. Eye & Contact Lens, May 2013
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In the January I-Site case report, we discussed the importance of proper scleral lens application training to avoid harm to the cornea. Proper removal of the device is equally important. Improper removal technique is very dangerous to ocular health. LASIK flaps and graft-host interfaces are particularly vulnerable areas. As practitioners, we focus on optimal scleral lens fitting to achieve our treatment goals of visual rehabilitation, ocular protection and comfort. But even with an optimal fit, patients may run into difficulties with removal of their lenses, especially if they need to remove their devices multiple times daily. Inability to remove a scleral device may contribute to patient panic and anxiety, and also it may lead to an adverse effect such as subepithelial hemorrhages - like in the two case reports presented in this month's I(n)-site-the-practice.
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The Contact Lens Specialist Symposium 2013 will take place 28th & 29th Septemb er 2013 in The Renaissance Hotel, Bath Road, London Heathrow. Keynote speakers will be Patrick 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
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Upcoming Events
- GPLI 2013 webinar series
- CLSS, September 28-29, London UK
- ESCRS, October 5-9, Amstrerdam NL
- AAO, October 23-26, Seattle US
- ECLSO, October 25-26, Munich DE
- Cornea & CL symposium, December 7-8, Houston US
- GSLS, January 23-26 2014, Las Vegas US
- NCC 2014, March 16-17 2014, Veldhoven NL
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I-site is an educational newsletter that is distributed on a monthly basis and provides an update on rigid gas permeable related topics (scientific research, case reports and other publications worldwide). I-site is objective and non-political. Its editor Eef van der Worp, optometrist, PhD, FAAO, FBCLA, FIACLE, FSLS is a lecturer for a variety of industry partners, but is not related to any specific company. Please contact us at: i-site@netherlens.com.
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