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International Newsletter and Forum on Rigid Gas Permeable Contact Lenses, Corneal Shape, Health and Vision |
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We need your help!
 The October issue of Contact Lens Spectrum features a special on (R)GP lenses, coordinated by Ed Bennett. It includes a fantastic summary of topics, setting the scene of (R)GP lens fitting and its opportunities. But a topic that clearly stands out and has attained a lot of interest recently is scleral lenses. As more and more practitioners are getting into fitting scleral lenses, it is clear that it's a procedure in progress and that we need to learn and educate ourselves to optimize this lens modality. What better reason to use the internet to share information? One item that is still part of the ongoing debate is what solution to use with sclerals. There are pros and cons regarding different solutions used, in which the discussion often goes back and forth between toxic reactions to the ocular surface on one hand and wettability and safety issues on the other hand. Please help us with our opinion! The next item in this newsletter contains a quick poll on which solutions should be used in scleral lens fitting. We will report back to you on this topic! For more insights on the discussion, also visit the sclerallens.org website. Eef van der Worp
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 If you fit large diameter (R)GP lenses, what solutions do you advise your patients to use for storage and insertion of scleral lenses?
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Corneal Ectasia after LASIK
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 Preventing corneal ectasia may not get the same attention it did a few years ago - but it continues to be very relevant. The 'Risk Score System' is frequently used to identify patients at risk preoperatively for ectasia. The system consists of five variables that can be rated on a scale from 0-4. This includes topography (zero points would be a symmetric bow-tie pattern), residual stromal bed thickness (300 microns or more would get a zero point score), age of the patient (age 30 or higher would be zero points - younger age adds risk), preoperative pachymetry (more than 510 microns would be zero points) and refraction (8D of myopia is zero points). If the risk numbers add up to 3, this would be considered moderate risk, 4 points or more is considered high risk. See link below for a slideshow on the system by R. Doyle Stulting on the OCN SuperSite, followed by a discussion with the audience on the system. For more discussion, also see the recent paper by Binder et al in the Journal of Refractive Surgery. They looked retrospectively at 1,702 myopic post-LASIK eyes (that did not develop ectasia) and found that 5.4% of eyes had a 4 point score preoperatively, which would have required the surgeon to advise against the procedure, and an additional 6.8% of eyes had a score of 3
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Stevens Johnson Syndrome/TEN
The October 2010 edition of I-site featured a case of a scleral lens fit in toxic epidermal necrolysis (TEN) in Great Britain. In response to this article, another such case of a patient who developed Stevens Johnson Syndrome/TEN after taking a non steroidal anti inflammatory drug (Ibuprofin) was reported. See the website that the father of the patient presents. Scleral lenses in this case could not be tolerated long enough for all day comfort at this point, and bandage lenses are used. Stevens Johnson Syndrome/TEN has been more frequently mentioned as an indication for scleral lenses. See also the website of the Stevens Johnson Syndrome foundation for more information on the condition. featured
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Virtual Reality
The future of contact lens fitting is here. Digital or virtual lens fitting based on corneal topography is widely available, and is especially popular in Europe. This results in better fitting characteristics that better respect the shape of the cornea. Improved lens comfort may also be achieved, and even better corneal physiology may be possible. It also makes it easier for practitioners to approach and fit complex cases. An example is this case report, which discusses a double reverse geometry lens designed using corneal topography in a post-LASIK cornea. Marco Tovaglia from Italy describes step-by-step how this was achieved.
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Clearly an Aberration
 An interesting study by investigators in Houston (USA) and Bordeaux (France) looked at the effect of pterygia on ocular aberrations. They found that the total higher order aberrations, but also each individual aberration (e.g. COMA, Spherical aberration, trefoil, tetrafoil and higher order astigmatism) were all statistically significantly increased when pterygia was present. This was correlated with the horizontal length and width of pterygia. (R)GP lenses may be able to correct this to some degree, but ocular aberration measurement may also play a role in future surgical intervention of pterygia. Check out the link below for a surgical video on modern pterygium surgical techniques by John A. Hovanestian on Eyetube. |
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Upcoming Meetings
2011
- Global Specialty Lens Symposium - Jan 27-30, Las Vegas USA
- Heart of America - Febr 11-13, Kansas USA
- Specialty Contact Lens Symposium, Febr 11-13, San Diego USA
- Vision By Design, April 29th - May 1st, Orlando USA
- EFCLIN, May 12-14, Barcelona ES
- BCLA conference, May 26-29 , Manchester UK
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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 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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