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Medical Forum / General / Vision / May 2005tough keratoconus fit
I've been referred for contact lens fitting of a 20 yo wm keratoconus patient who has never worn CLs Unaided acutities R 20/400 L 20/400- Existing SRx (2 yo): R 0.00 - 7.00 x 19 20/60+ - L 0.00 - 6.00 x 135 20/60++ My refraction: R +2.00 -12.00 x 38 20/30- - L 0.00 -6.50 x 134 20/40 - Ks were R 46.25@20 55.00 4+ distorted (egg shaped) mires L 45.00@165 57.00 4+ distorted (egg shaped) mires Corneas have a classical cone shape, but are otherwise normal; no scarring or dangerous thinning. I will ordering trial RGP torics for him, and was wondering if anyone has any suggestions on the fit. Also, would you even attempt a spectacle Rx as a back up or just leave it alone? Can a normal lab even fabricate a 12 cyl? Thanks w.stacy, o.d. Clearly RGP is the best first defense for the refractive error brought on by keratoconus, however two procedures, one surgical and one therapeutic, may provided a better short-term and much better long-term result. Intacs (intrastromal corneal ring inserts) have been shown in many studies to not only provide significant normalization of the corneal shape, but to reduce the progression of keratoconus. A new, and thereby more controversial, therapeutic technique for keratoconus is Corneal Collagen Crosslinking with Riboflavin (C3-R). This is a process of keeping the eyes flushed with a special riboflavin ophthalmic solution and exposing the cornea to controlled ultraviolet light for 30 minutes. Many surgeons throughout the US will do Intacs, and some use the Intralase femtosecond laser to create the channels for more precise accuracy of depth and radius. As far as I know, Brian S. Boxer Wachler, MD in Beverly Hills is the only doctor in the US who does C3-R, with Theo Seiler, MD doing it in Geneva. I'm a cynic at heart, and I am always skeptical of anything new that seems too good to be true, but I have seen the scans of a 10.00+ diopter cone almost perfectly flattened by a combination of Intacs and C3-R. We will have these images on our website with the update scheduled for later this month. I apologize that they are not available today. Glenn Hagele Executive Director Council for Refractive Surgery Quality Assurance Email to glenn dot hagele at usaeyes dot org http://www.USAEyes.org http://www.ComplicatedEyes.org I am not a doctor. Far out stuff. I doubt if this 20 yo will want to go to B. hills or to Geneva any time soon... I think I'll start with the RGPs and see how we do. Let us know when you've got the pics. How much astigmatism did the 10 D. cone have, or was 10 D. the cyl? Have you seen intacs alone straighten out much cyl? w.stacy, o.d. > Clearly RGP is the best first defense for the refractive error brought > on by keratoconus, however two procedures, one surgical and one [quoted text clipped - 36 lines] > > I am not a doctor. The cyl was 10.00 D If C3-R makes it through peer review, treatment for keratoconus will be significantly changed. I'm sure you already know about Intacs, but the ones in the US only correct up to 3.00 D myopia, so not all of the correction could have been just the Intacs. I assumed that the additional correction was due to the different nature of the keratoconic cornea, but I also have received topos of C3-R only, and see the same kind of normalization. In any case, RGPs are and probably always will be the first line of defense. I hope to have the updated website published by Monday, which will be just in time for our 3 millionth visitor. Glenn Hagele Executive Director Council for Refractive Surgery Quality Assurance Email to glenn dot hagele at usaeyes dot org http://www.USAEyes.org http://www.ComplicatedEyes.org I am not a doctor. Here are those articles: Keratoconus http://www.usaeyes.org/faq/subjects/keratoconus.htm C3-R http://www.usaeyes.org/faq/subjects/c3-r.htm Intacs http://www.usaeyes.org/faq/subjects/intacs.htm All articles are primarily for people with interest in refractive surgery subjects. Any comments would be welcomed. Glenn Hagele Executive Director USAEyes.org "Consider and Choose With Confidence" Email to glenn dot hagele at usaeyes dot org http://www.USAEyes.org http://www.ComplicatedEyes.org I am not a doctor. Excuse me if I don't post a link to it, but I will if pressed, but at least one study showed that significant endothelial apoptosis resulted following this ultraviolet light treatment. This has made me a bit leery of trying it out on post-RS patients. I think that if the next stop for a keratoconus patient is a corneal transplant, then the combination of Intacs and C3-R might sound like a pretty game option to try first. DrG The study is probably the one where UVA with riboflavin was performed on rabbit eyes. The amount of endothelial loss varied greatly with the amount of light applied, the distance the light was from the eye, the timing of the riboflavin drops, and the thickness of the cornea. More light,closer light, less drops, and thinner corneas caused more damage. The consensus on C3-R seems to be that if the patient is looking down the barrel of a transplant, then there is not much risk of doing C3-R. If the patient has moderate keratoconus, Intacs alone seem to be best, when the patient becomes contact lens intolerant. If (and this is a big "if") endothelial cell loss is found with all C3-R, but C3-R resolves the refractive changes and stabilizes the cornea, and if (another big one) the patient is moderately advanced, then the use of C3-R with Deep Lamellar Endothelial Keratoplasty (DLEK) may (a very big "may") be appropriate. It is very early in C3-R's life cycle. It holds promise, but we all need to look closely. Trust, but verify. Glenn Hagele Executive Director Council for Refractive Surgery Quality Assurance Email to glenn dot hagele at usaeyes dot org http://www.USAEyes.org http://www.ComplicatedEyes.org I am not a doctor. ...plus several more using rabbit and porcine corneas and demonstrating keratocyte apoptosis. I am often astounded by the speed with which some doctors go from the animal model to the human. DrG The speed is even more amazing where there are problems in the animal eyes. Glenn Hagele Executive Director Council for Refractive Surgery Quality Assurance Email to glenn dot hagele at usaeyes dot org http://www.USAEyes.org http://www.ComplicatedEyes.org I am not a doctor. >Also, would you even attempt a >spectacle Rx as a back up or just leave it alone? Can a normal lab even >fabricate a 12 cyl? Thanks > >w.stacy, o.d. A specials lab will be able to do it. One of the labs I use sends this work to Epic Labs. They do business with surface labs only. You will need to have your lab contact them directly. They do slab-offs, twenty diopter prism segs, bonding, just about anything you can think of, and some things I never knew could be done (like the lens they showed me that magnifies but measures plano sph in the lensometer). Regards, Robert Thanks. Think I'll just wait and see if he can wear the CLs. If so, that might (and hopefully will) have some ortho effect. Probably wishful thinking. Can you imagine wearing a 10 or 12 cyl in glasses? The words squishy and squashy come to mind. I remember getting my first glasses. They had 1.5 cyl. and I almost fell flat on my face as I walked out of the office... w.stacy, o.d. > A specials lab will be able to do it. One of the labs I use sends this work to > Epic Labs. They do business with surface labs only. You will need to have your > lab contact them directly. They do slab-offs, twenty diopter prism segs, > bonding, just about anything you can think of, and some things I never knew > could be done (like the lens they showed me that magnifies but measures plano > sph in the lensometer). If this patient has never worn contact lenses before, then he will be in for a rude awakening. Keratoconus fits tend to deviate quite a bit from the ideal. My recommendation would be to try Macrolenses in a keratoconus design. They are as large as a soft lens and about as comfortable. Since they rest partially on the sclera, they tend to center well. I know there are some other manufacturers making these large lenses as well. DrG I've heard of those and will ask my cl lab about them. Decentration is probably going to be the issue with ordinary lenses, but we shall see. I'll post my results. Can the Macrolens be popped out like orginary RGP or do you need a suction cup? Given the geometry, there's probably a fair amount of tear pooling under there. w.stacy, o.d. > If this patient has never worn contact lenses before, then he will be > in for a rude awakening. Keratoconus fits tend to deviate quite a bit [quoted text clipped - 6 lines] > > DrG > I've heard of those and will ask my cl lab about them. Decentration is > probably going to be the issue with ordinary lenses, but we shall see. [quoted text clipped - 14 lines] > > > > DrG The Macrolens is a patented design by C&H Contacts, Dallas, Texas. The blanks required are very large, and are probably not going to be available at a lab near you. It was just a suggestion. I know that the Rose K is a popular design, but it is still intralimbal. As such, it will never match the comfort of a cornea-scleral design. The larger lenses can be removed using the "scissors" method, or with a plunger. A fair amount of pooling will occur, but careful attention to base curve will keep it to a minimum. Of course, you will need to invest in a trial lens set to get started. However, once you have made the investment, this type of lens will open up other opportunities -- for example tough soft toric fits with corneal cylinder can be put into a Macrolens. DrG Of course, you will need to invest in > a trial lens set to get started. Of course. Just what I need, more trial lenses. Any idea on the cost? Thanks w.stacy, o.d. Tell me about it. I haven't any idea of the cost of the trial lenses. I have about 5 Macrolens kits. Half of them were given to me to play with. With 12 diopters of cylinder, you've got quite a case. DrG At issue with the costs, to physician and patient alike, contact lenses for keratoconus are not correcting refractive state, but are a prosthetic for a diagnosable disease. As such, they should be covered under the patient's major medical insurance plan. Most optometrists don't deal with much more than an Knox-Keene type plan like VSP, so wading into the ever deepening waters of medical insurance reimbursement is not for the faint of heart. Additionally, staff will always initially deny reimbursement for contact lenses so every case will need to go to appeal. Our organization has just put together an ad hoc committee to create guidelines for medical directors of insurance plans to help define and justify when treatment for keratoconus - including contact lenses - should be covered under the plans. Hopefully this will help patients get the reimbursement they deserve and give physicians a road map to reimbursement. Glenn Hagele Executive Director Council for Refractive Surgery Quality Assurance Email to glenn dot hagele at usaeyes dot org http://www.USAEyes.org http://www.ComplicatedEyes.org I am not a doctor. Bill, I don't know whether the same system is available in the States but in the UK the licensed maunfacturers of the Rose K2 lens will let you borrow a fitting set FOC. I have started using this system for the odd keratoconic I see and find the lens gives very good results, with advantage of talking to the manufacturers they can tweek the lens in many ways to give a good fit. Regards Ian Hodgson - Isle of Man > Of course, you will need to invest in > > a trial lens set to get started. [quoted text clipped - 4 lines] > > w.stacy, o.d. Thanks for all the responses. I've ordered the k.c. set from C% H. They have loaner lenses and even loaner sets, but after talking to them, I'm going for the $400 fitting set. It should make the fitting a lot quicker and easier than dinking around a lens or 2 at a time. If I like how it works on this case, I might even go for the regular set and the post refractive surgery set, designed for problem cases. Maybe a niche developing here... w.stacy, o.d. I think Dr. Gemoules has shown that there is most certainly a niche for fitting post refractive RGPs and keratoconus patients. Glenn Hagele Executive Director Council for Refractive Surgery Quality Assurance Email to glenn dot hagele at usaeyes dot org http://www.USAEyes.org http://www.ComplicatedEyes.org I am not a doctor. > The Macrolens is a patented design by C&H Contacts, Dallas, Texas. The > blanks required are very large, and are probably not going to be [quoted text clipped - 10 lines] > > DrG Hi Folks, as a keratoconus guy I would like to know about a comparison of the Macrolens mentioned above and the konus lenses done by the Falco company in Switzerland, which I wear since some years. Is there anybody around who can contribute some useful info about that issue? Thanks in advance Torsten I personally am not familiar with "konus" lenses by "Falco." Macrolenses range in diameter from 13.5 mm up to 15.0 mm. They are very large. Any lens of approximately that size is called a cornea-scleral lens. A "mini-scleral" is about 16 mm to 18 mm, and a scleral lens larger still. DrG > I personally am not familiar with "konus" lenses by "Falco." > [quoted text clipped - 4 lines] > > DrG Falco has a good description of their products on their website: http://www.falco-kontaktlinsen.com/Produkte.htm Unfortunately I did not see an english version of it. But they offer cornea-scleral lenses among others. The description of these lenses (in pdf format) is very good, I think, and should be mainly understandable for english readers because of the international termina being used. Torsten > Hi Folks, > [quoted text clipped - 7 lines] > Thanks in advance > Torsten My advice is that if your current cl's are fitting well, with good vision and comfort, leave well enough alone. Sometimes, doing a re-fit just because there is something "newer" out there will result in problems that didn't exist before. frank |
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