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International Newsletter and Forum on Rigid Gas Permeable Contact Lenses, Corneal Shape, Health and Vision |
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'Happy' new year
In the Netherlands, new years' eve has always been celebrated with spectacular fireworks. This comes with a price. Dutch citizen spent 68 million Euro (97 million US$) on fireworks this year (3 million more than last year). But it also comes with another price: last year 315 eyes of 286 people needed urgent eye care around the turn of the year. In one-third of these cases the eye damage was considered permanent. Worse: 24 eyes were reported legally blind, and 15 even had to be enucleated. In 57% of people the damage reportedly resulted from their own lit fireworks, the rest from other people's fireworks. The data for this year seems equal to that of last year. Not a pretty sight, which opens the discussion of whether consumer fireworks should be permitted or not. It is clear that the eyesight in the mentioned patients most probably won't get to 20/10 this year, but hopefully can be restored to a reasonable level. Most probably by using (R)GP lenses, of which at least some may be large diameter scleral or semiscleral lenses. Check this I-site newsletter for a very illustrative article on what semi-scleral lenses can do by Sophie Taylor-West in I(n)site the practice, and another article on full-scleral lenses and lens designs. I wish everybody all the best for 2010, especially those who didn't have a good start to the new year.
Eef van der Worp |
| Presbyopia & Contact Lenses |
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Multi-focus I: drivers' seat
The number of publications in the literature on presbyopic contact lens solutions is not in proportion to presbyopes' desire for a good alternative for glasses. In other words: hardly any research, at least not published, goes into presbyopic contact lens corrections, even though the potential is huge. A interesting article by Michael Collins' group in Brisbane, Australia looked at different presbyopic vision corrections and whether they alter the pattern of eye and head movements when viewing and responding to driving-related traffic scenes. Five different vision corrections were tested: distance single vision lenses, progressive addition spectacle lenses, bifocal spectacle lenses, monovision contact lenses and multifocal contact lenses (soft). They found that different presbyopic vision corrections alter the eye and head movement patterns, more so with the spectacle lens corrections. The presbyopic corrections were associated with a longer path length of eye and head movements and a greater number of saccades compared to contact lenses, which may affect some aspects of driving performance. |
| Presbyopia & Contact Lenses |
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Multi-focus II: what lens?
It is clear that there is no 'one size fits all' solution for presbyopic patients, and fitting presbyopes should be a multi-focal approach. For instance, some prefer monovision, while some prefer multifocal solutions. See both perspectives in the point/counterpoint discussion in the December issue of Contact Lens Spectrum. Also see a 2009 article in Optometry Today for a nice overview of presbyopic lens solutions, including (R)GP lenses, by Judith Morris. Most eyecare practitioners would agree that (R)GP lenses offer the best optical solution, but they are often uncomfortable with the fitting process and overwhelmed by the possibilities. An article in the Boston Update gives an overview of when to fit (R)GP and when to fit soft presbyopic lenses - as well as when to try translating and when to try simultaneous designs. Eyelids play an important role when fitting (R)GP lenses, which is beautifully addressed and illustrated in Craig Norman's column 'Keeping a Lid on GP lenses'. For more on presbyopic lens corrections, the Global Specialty Lens Symposium (GSLS) will devote a whole session in the fundamentals course to this topic. |
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The story of the large lens
 The Boston Foundation for Sight, founded by Perry Rosenthal, is one of the most experienced centers worldwide in fitting scleral lenses. An article by this founder and pioneer on the 'Evolution of an Ocular Surface Prosthesis' covers not only the history of scleral lenses, but also looks at lens designs and covers the clinical indications for this scleral lens. The lens design described is considered a 'full-scleral' or large scleral lens design, typically 20mm or larger. A discussion on scleral lens fits by experts from around the world was published in the Boston Update with the title 'Super-size It". In addition to these large diameter lenses, there seems to also be a place for smaller semi-scleral lenses.See a case report by Mark André and Patrick Caroline in the December issue of Contact Lens Spectrum as well as I(n)site the practice below. Much more, on scleral lens fitting will be presented at the GSLS in Las Vegas at the end of this month. |
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The 'hard' truth
We can't stress enough how safe (R)GP lenses are-but do we make this clear to our patients as well? It is sometimes hard to believe that other factors (e.g. comfort) seem to play a much more prominent role. The hard truth is that it is hard to find any studies that compare ocular health with soft and (R)GP lens wear that are not in favor of (R)GP lenses. A recent study out of Japan found the opposite effect though. The average level of conjuctivochalasis was higher in contact lens wearers, and it was higher in (R)GP lens wearers than in soft lens wearers. The incidence was also found to be higher in older individuals than in younger subjects. More on conjunctivochalasis including its symptoms and treatment options is available via the link below.
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A problem solver
Sophie Taylor-West from the United Kingdom has fit many patients with corneo-scleral lenses. Here she reports on just a few of these successful cases from her practice in London. One patient had keratoconus. Another underwent bilateral radial keratotomy in 1988 and subsequently developed high hyperopia and corneal astigmatism. There was one patient with a severe Pseudomonas infection OS that resulted in a full thickness corneal graft and suboptimal visual acuity. Another patient presented with a history of keratoconus and bilateral INTACs treatment. Finally, she also successfully fit a post LASIK patient with these 14-15mm diameter lenses. See this month's I(n)-site-the-practice for the full stories and outcomes. |
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Lost in translation?
A 'live' picture of a concentric multifocal lens in action is shown here. While most current concentric lens designs are simultaneous systems, this concerns a translating lens design. The subject is currently using the periphery of the lens, making full use of the translating properties of the design. The concept of the different concentric lens designs is difficult to explain to students, even more so abroad because of language differences. But the patient is often not lost in translation with this lens design, since full optical performance can be achieved for far and near. Photo: Kees Broos (the Netherlands). | |
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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-politcal. Its editor Eef van der Worp is a lecturer and a consultant for a varity of industry partners, but is not related to any specific company. Please contact us at: i-site@netherlens.com. | |
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