|
|
International Newsletter and Forum on Rigid Gas Permeable Contact Lenses, Corneal Shape, Health and Vision |
|
|
|
|
|
|
|
|
|
|
More (R)GP than multifocal lens fits worldwide!
Professor Nathan Efron continues his 17-year-old quest for the
demise of (R)GP lenses. He was proven wrong on his prediction of 2000 (that
(R)GP lenses would have vanished by then), and later regarding his prediction
of 2010, but the quest still continues. His latest work is an article in Contact Lens and Anterior Eye on the
subject: orbituary - rigid contact lenses. Discussion on this topic is good, as I have mentioned in
previous publications. And a critical note toward the (R)GP lens industry is
actually good for a profession that wants to be taken seriously. I have debated
Nathan recently at the NCC 2010 meeting in the Netherlands, with the pro's and
con's evenly balanced either way. It was fun. But the current paper highlights
the matter from only one side and is therefore non-balanced and non-objective-and
I think, in all honesty, not very scientific. There is not much more to be said on
the subject from here, other than perhaps this: According to the Eurolens
research survey data, of which Nathan is one of the initiators, more (R)GP
lenses are fitted worldwide than multifocal lenses.
Think about that one Nathan. And please, show a little respect to the (R)GP
lens professionals who are trying their very best to give patients the best and
safest contact lens correction method available today. The world would be a
different place to many people if there truly were no more (R)GPs available. Eef van der Worp |
|
Diagnosing Dystrophies
"Diagnosing a corneal dystrophy seems like it should be a straightforward task. You simply need to note the age of onset and clinical characteristics, ask questions about affected family members, and then run to your nearest textbook to connect the dots. But, what if it doesn't look exactly like the picture in the textbook?" This is how an article in Review of Cornea & Contact Lenses, a supplement to Review of Optometry, starts based on the international committee for classification of corneal dystrophies (IC3D). The article covers epithelial, Bowman's layer, stromal, Descemet's and endothelial dystrophies. |
|
What is the best lens fit to reduce ocular aberrations?
 The aim of this small study from the University of Manchester
was to investigate the effect of (R)GP lens fitting on visual acuity and ocular
higher-order aberrations by systematically applying (R)GP lenses with different
back optic zone radii (ranging from 7.40 to 8.10 mm in 0.10 mm steps). The
results showed that a flatter lens fit led to a reduction in higher-order
aberrations and improvement of visual acuity in this moderate keratoconic
patient. Both the vertical coma component and the third order root mean square
error were reduced, and the best corrected LogMar acuity improved. |
|
Hopes for High Myopes?
Orthokeratology in the USA is approved for up to 6D of myopia, otherwise
it would be an off-label procedure. Many of us in clinical practice preach that
with up to 4D of myopia the results are usually good; beyond that
the outcome may get less predictable. This way, thousands of patients have been fitted around the world, and the magic of orthokeratology continues. Higher myopes are often left out though, which can be very frustrating sometimes for friends or family of successful patients using orthokeratology. But incidental cases sometimes show surprising results. Please see link for the full case report by
Bruce Williams of Seattle Vision in Seattle (USA). Furthermore: see this link for information on the upcoming Orthokeratology Academy of America meeting in October in Chicago (USA), of which Bruce Williams is a board member, with much more on corneal reshaping. |
|
(Not) The Holy Graft
 Although a well performed penetrating keratoplasty can truly be a work
of art, it is not quite yet the holy grail in many cases since the visual
outcome can often be suboptimal. The National Keratoconus Foundation estimates that about
15 percent to 20 percent of keratoconic patients will eventually undergo
surgical treatment for the condition. Scleral lenses have proven to be very
successful in many cases, as they bridge the entire - fragile - cornea. For the
removal of scleral lenses, a suction cup is often used. Extra instructions
should be given to these patients to ensure that the lens is still present when
the suction device is placed, as the corneal graft is sometimes mistaken for a
lens on the eye. Depending on the healing time and speed, this may dislodge the
corneal donor button, and the end result may be nowhere near pretty. More on this on the sclerallens.org/forum (registration required). |
|
Microns
In an article on (R)GP lens material technology in the August edition of the I-site newsletter it was described that 0.04mm and 0.05mm thickness
reduction could potentially be achieved with high-index materials. It should
have said that this is respectively 40 and 50 microns difference (instead of 400
and 500 microns). |
|
|
|
|
|
|
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. |
|
|
