All of us Vs Keratoconus

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Post Info TOPIC: Why you should NEVER have Crosslinking or TPRK done.

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Date: Thu May 11 8:40 PM, 2017
Why you should NEVER have Crosslinking or TPRK done.

ScottP, I think both our perceptions of "most commonly used" is heavily influenced by the comparatively few eye care professionals (ECPs) that we have experience with. I haven't pursued scleral lenses so I really have no idea of what type of scleral lenses ECPs in Southern California are fitting. I did look at the Europa lens and I agree that it seems like another step forward in KC lens design. I think the sMap3D from Precision Optical Metrology that Visionary Optics is promoting along with the Europa lens is even more interesting.

But there is only one company, Visionary Optics, that supplies the Europa lens. ECPs that use Visionary Optics as their scleral lens provider probably are migrating to the Europa design. But ECPs that do not already use Visionary Optics probably are sticking with whatever they know and use now. My guess is that I would have to make a lot of phone calls to find someone in Southern California with experience in fitting the Europa lens for a KC patient.

The problem with all KC lens designs is that each one requires the ECP to have experience with the particular design to be able to fit it effectively. Most (all?) lens designs require the ECP to purchase a fitting set to even begin trying to fit the lens. When you factor in that the incidence of KC is supposedly something like 1 in 2,000 patients, an ECP who works 250 days/year (a hard working ECP!) would have to do 8 new lens fittings per day to encounter even 1 KC fitting in a year. Even if we factor in some concentration of KC patients by directing them to specialists in fitting medically necessary contact lenses, I think it would be an exceptional ECP who sees more than 50 KC patients a year for an initial contact lens fitting. Trying to develop expertise in KC fitting for more than a few lens designs when you see so few KC patients is a challenge. And trying to justify technology like sMap3D for the number of scleral lens fittings that I would guess most ECPs do would be hard. It took a long time before corneal topography became widely used. And even now it is not universal. I am not sure the problem of providing the available range of KC contact lens designs to a significant number of KC patients is one that can be solved.

I am intrigued by the inability to fit Europa on your right eye because of lenticular astigmatism, which I understand to be astigmatism due to an issue with your crystalline (internal to the eye) lens. My understanding is that a ballasted scleral lens could be fit with the usual tear film correction of the irregular KC corneal surface and a toric front surface added to correct the lenticular astigmatism. This seems like it would work even better if sMap3D was used because apparently most sclera are toric and the outside edge on the back of the Europa can be matched to the sclera which stabilizes rotation of the lens without the need for ballast. Is my understanding of what's possible wrong?

In any event, I think Dr. Gemoules at LaserFit probably has the most advanced technique for fitting a scleral lens for KC. Using wavefront technology to determine the optical aberrations that need to be corrected by the lens is a giant leap in designing the refractive aspect of the lens. It is unfortunate that no one seems to have any interest in adopting the techniques that Dr. Gemoules has developed. But again, the realities of developing this kind of expertise and justifying the cost of the specialized equipment needed set in. Good luck with LaserFit! I look forward to hearing your experiences.


Date: Thu Oct 19 1:52 AM, 2017

Scott P, if you are in the states and still having pain, I would recommend seeing Dr Brian Boxer Wachler in California for a consultation. He is a top expert in Keratoconus. The consult fee is reasonable $400 and includes a very thorough exam followed by a meeting with him where he does not rush you at all. I had treatment with him last month for KC and am very happy with my results, at least so far. Much better than I expected. To my understanding, he is also good at fixing a mess caused by other eye surgeons. Anyway just a recommendation. If you want to email me with questions about my experience or to verify I am a real patient of his, you (or anyone else) can email me at bwaventura at aol. I am so happy with my results that I want to share it.



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Posts: 30
Date: Wed Nov 15 4:53 PM, 2017

JimKC, another well informed post from you.

Having had experience fitting different types of lenses and having my favorite lens sold to another company taught me not to put all my eggs in one basket.  I think it's kind of ludicrous where a practitioner's credentials are determined in large measure by how large his assortment of trial lenses is.  It's really quite simple: figure out the actual shape of the eye and design a lens to fit it.  Simply stated, that is the philosophy behind Laserfit.  You mentioned the sMAP3D, and as well there is another scleral scanner called the Eaglet ESP which operates on a similar principle, i.e. using a fluorescein dye to stain the tear film.  Back in 2007, the only instrument capable of imaging the entire eye well out in the scleral region was the anterior segment OCT by Carl Zeiss.  It was a no-brainer purchase decision.  It never fails to give me good images, even in the presence of lots of bumps and a dry surface.  The second instrument is an aberrometer, which maps the prescription by sending 256 individual laser beams covering the entire pupil to the back of the eye and tracing their destination.  It never fails to give me a power map of the eye.  In the case of a normal eye, the power of the eye is more or less consistent across the pupil.  With keratoconus, the power changes dramatically from one section of the pupil to an adjacent section, and it is that which causes the problems.  No lens can satisfactorily follow the amplitude of those changes exactly, hence there is often leftover aberrations even when a scleral lens is worn.  So we go back and "clean up" those spots that are still misdirecting the light to the wrong parts of the retina.  When we do that, things become sharper, brighter, and there is less glare and double vision.  Sometimes we can get rid of all of those artifacts, and sometimes we can only make them significantly better.  I have different strategies I pursue in order to get the job done.  The workhorse is the old Zernike Polynomials, an infinite series of polynomial formulas that when combined approximate the optical distortions cause by KC.  Other times I use custom aspheric designs, etc., depending on how the aberrations occur in the eye.

I think this is the logical way to treat keratoconus.  Unfortunately one needs a couple of expensive scanners which are not really prohibitive to own.  Many practices use an OCT, mostly for the retina.  Very few offices have an aberrometer because they can't really bill for it.  Until I acquired an aberrometer, I really had no idea how KC patients saw the world.  The neat thing about it is that it constructs an image based on the retinal spot diagram (i.e. the light distribution on the retina) that is remarkably accurate, and which I show the patient for discussion. After each lens fitting I take a scan and look at the sharpness of the image improve, as well as the stray light diminish.

It's taken a good deal of work, and now I am proud to say that I am now working with our first remote clinic to see if we can do this half a world away.  Laserfit has now grown its first wings....

-- Edited by GRS on Wednesday 15th of November 2017 04:55:20 PM

-- Edited by GRS on Wednesday 15th of November 2017 04:56:59 PM

-- Edited by GRS on Wednesday 15th of November 2017 04:57:49 PM


Dr. G.

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