Month: April 2015

EpiOn EpiOFF CrossLinking

Q:
Is there any evidence that Riboflavin-soaked epithelium (or just plain old intact epithelium) blocks UV A to the stroma?
Dr. P
A:
Why are so many people so averse to removing epithelium for CXL? Is this a religious prohibition or something?;)
I remember assisting retina surgeons at Harvard/MEEI (including my uncle) and they’d remove epithelium at the slightest excuse for a better view. There are PRK and ASA surgeons out there who are doing this thousands of times each and every year without delayed healing, pain, or scarring
So I’d like a response from the surgeons who are trying so hard to make epi-on CXL approach the proven efficacy of epi-off CXL, why they’re so averse to removing epithelium, when with a clean en-bloc epithelial removal, a proper BCL, and the right postop meds, there’s no pain and almost zero risk of infection?
I’d like to restate a query nobody responded to:
Why spend so much effort on such a limited application (CXL) when if all of us spent that time optimizing epithelial regrowth, that’d be more useful in a number of eye surgeries literally 100,000x as numerous?—

Emil William Chynn, MD, FACS, MBA
Q2:

Emil,
If the outcomes are the same – what is the advantage of removing the Epithelium with CXL?
In our study – when patients have Epi-On CXL
1. Patients are able to return to work 1-2 days after their procedure
2. The risk of infection is exceptionally low.
3. One of the risks with Epi-Off CXL is corneal haze – and this risk is dramatically reduced with Epi-ON
4. Patients do not need a bandage contact lens
5. Patients can return to their RGP, scleral or soft toric contact lenses 2-3 days after their procedure
6. There are fewer office visits.   After the 1 day postop visit, there is no need for a second visit – other than to monitor changes.  So in our protocol, we have patients return at 3 months.  With Epi-Off – patients would need a visit a 5 days postop to confirm that their epithelium has healed.  These are steep corneas, so epi healing can take longer in some patients, requiring additional visits
7. Less steroids are needed with Epi-ON – since the risk of haze is dramatically lower than with Epi-Off

These are just a few advantages.   Again – in our study, when confirming there is sufficient riboflavin in the corneal stroma prior to UV light administration, we have had excellent results.

Best regards

Bill

A2:

That’s a big if Billy
If you look at 100 CXL studies in both the worldwide peer and non-peer reviewed literature
You’d probably see something like this:
66 studies showing epi-off more effective
34 studies showing epi-on equally effective
0 studies showing epi-on more effective
Which raises the following very important question that I believe has actually never been voiced or addressed:
If epi-on is truly equally effective, wouldn’t normal statistical variation mean that there should be at least ONE study showing it’s MORE effective?
To make my query more intuitive, consider the following example:
Antibiotic A and B are in reality equally effective
100 doctors around the world compare them in 100 studies both formal and informal
The result would never look like this:
66 studies showing A more effective
34 studies showing B equally effective
0 studies showing B more effective
If this WERE the result, would anyone then conclude that A and B are equally effective? Of course not! We’d all conclude that A is obviously (at least somewhat) more effective than B
You’d need a n of like 1000 eyes in each arm of your study, Billy, to convince me that epi-on is equally effective as epi-off. Obviously that’s not possible
So think of the above “thought experiment” as a “virtual meta-analysis” oh wise fellow Kera-netters, and tell me if my logic is solid or not??

Emil William Chynn, MD, FACS, MBA

 

 

CXL and epi-off?

Q:

List,
>
> I am a member of the large keratoconus group on Facebook.  I dont really post much, but its interesting to read what patients with this condition are writing about.  Granted these are lay people, but often someone with a disease learns a lot about it.
>
> There is a constant ongoing debate about epi-off vs epi-on.  Someone decides to get CXL for their kid, the surgeon does it one way, and then they start reading that maybe the other way is better(and this can go either way).
>
> So, is there a consensus yet?  Is one method now preferred over another?
>
> Thanks

 

A:

Epi-off is more proven
All studies show epi-off is more effective
Or the same effectiveness as epi-on

No studies show epi-on is more effective

Because some surgeons have had problems with delayed re-epithelialization and subsequent pain or rarely infections or scarring, many are calling for research to make epi-on as efficacious as epi-off (eg via iontophoresis)

I say it’s much easier trying harder to get the epithelium to grow back faster

It’s possible that surgeons who have more experience dealing w epi removal and regrowth (eg those performing a lot of lasek and PRK) are the ones having faster healing after epi-off cxl

And the ones who don’t have as much experience (like those only performing lasik) are the ones with longer healing times after epi-off cxl, who then move to epi-on

Anyway, that’s my summary, and 99% of eye surgeons would agree with the first half, and the majority (>50%) might agree with the second half;)

Hope this helps!


Emil William Chynn, MD, FACS, MBA
Harvard/Columbia/Dartmouth/NYU/Emory-trained
1st eye surgeon in NY to get LASIK himself (1999)
Performed 5,000 LASIKs from 1996-2002
Switched to non-invasive LASEK in 2003
Have performed more LASEKs than any MD in US

Schirmer test

Q:

I saw a patient today for the first time who is an internist has been treated for dry eye for years.  She really looked to me more like chronic inflammatory OSD due to blepharitis and possible allergy with Rosace, plugging of the glands, loss of lashes, conjunctivochalsis etc.  She had no plugs in but had a normal lacrimal lake interrupted by conjunctivochalasis and tear osmolarity was 289 OD 291 OS.  No lissamine green stain.

What was interesting was that her Schirmer strips was only about 4mm before anesthetic but 13mm or so with anesthetic in both eyes.  I know that this is not the most reliable test in the world but still…..I’m having a hard time explaining this to a physician who is a patient.  She says she has had plugs in the past and benefited from them but they fall out and that she tried Restasis and it did not help.  

Wondering if anybody can explain why that might be to me.  Usually it’s the other way around with Schirmer’s .  Perhaps I’m missing something here so I thought I’d throw it out to the group.

Steve

 

A:

regarding the validity of Schirmer’s testing:

i do some expert review/testimony work, and highly suggest that all American ophthalmologists starting out do this, as it is essentially paid training to learn how to reduce your own liability risk (by seeing how others may have screwed up, not typically only or even primarily medically, but usually also additionally or primarily non-medically, like by poor documentation, etc)
you also get to see the legal system at work, so you have a better understanding of the 3 parts that you need to convict in a medical malpractice case in the US (negligence (departure from standard of care) + causation + damages). you also surprisingly get a higher level of respect for the vast majority of lawyers, who will not take cases that they don’t think are deserving (with the obvious 1% exception who bring bs cases forward with the MO of seeing “what sticks to the wall”)
so in court, i had to defend a refractive surgeon who had a patient accusing him of causing permanent debilitating DES postop, who “did not even do the basic test for DES preop, or Schirmer’s”
in court, i made the following points about Schirmer’s testing (after conducting a literature review):
  1. highly variable results between testers and even with the same tester on repeated testing
  2. large variations in results depending on time of day or which day was tested
  3. poor correlation to other recognized measures of DES
  4. no generally accepted way to even perform the test
  5. no generally accepted values of normal or abnormal
  6. no generally accepted practice on what to do with test results in terms of therapy
  7. many top cornea/refractive specialists have therefore abandoned routine Schirmer’s testing
  8. therefore, it is NOT a “gold standard” and many top surgeons wouldn’t even call it a “bronze” standard
the jury was convinced by my logic, and the defendant was unanimously acquitted
so that is a rationale that at least legally demonstrates that Schirmer’s testing is not nearly as accurate as one would believe, given how much emphasis is given to it in residency training and on ABO testing (which often isn’t very well related to what we need to know/do in real clinical practice)
i, myself, tell my fellows to use Schirmer’s w anesthesia (wo i think has almost no value as you might as well just stick a grain of sand in their eyes and see how much reflex tearing they produce), make sure to blot the fornices very carefully beforehand, make sure their eyes are closed throughout the test so as not to activate the lacrimal pump, and only use results that are extreme (eg less than 5 is dry, more than 10 isn’t that dry, 5-10 is equivocal). i would say we only do this about 10% of time preop, and rely more on the pt’s telling us about dryness w CLs, and other findings (eg SPK, etc)
hope this helps add perspective to this debate

———————————————————————————————–
*Emil William Chynn, MD, FACS, MBA*
*Dartmouth / Columbia / Harvard / Emory / NYU-trained *
*1st eye surgeon in NYC to have LASIK himself (1999)*
*Switched to SafeSight for better safety & vision (2005)*
*Performed highest Rx (-22.00) ever lasered in USA (2010)*
*Only High-Volume Pure Non-Cutting Refractive Surgeon in USA*

 

Bandage lenses for PRK or LASEK

Q:

For many years I’ve been using the Alcon “AirOptix Night & Day” plano contact lens (base curve 8.4, diameter 13.8) as my go to bandage lens after PRK, but I’ve noticed that some of these fit a little tight and some a little loose.

Enrique Corral suggested recently that exchanging the bandage lens on POD1 has helped his patients with pain, and I’ve started doing that as well, although my numbers are too small to say for sure if it helps.

 

In any case, I’m wondering if there is a better contact lens to use, or, should I alter my strategy so as to incorporate different base curves for different patients.  If so, should we use the pre-op base curve to guide selection, or should we use the new calculated central base curve to guide our choice?

 

Perhaps I’m over-thinking this, but I welcome any suggestions.

 

Richard

Savannah, GA

A:

Perhaps I can contribute my experience with a “larger n”
Based on my n=15,000 eyes of surface ablation, probably 1,000 PRK, 4,000 epiLASEK, 10,000 LASEK I’d recommend:
1. Don’t exchange the lens if it’s a proper fit as this just delays healing and may cause the new epi to come off
2. If you need to refit the lens routinely on POD 1 that probably means you’re fitting too tight
3. A loose fit is better than a tight fit, BC the latter causes hypoxia edema delayed healing and poor vision
4. Don’t stick the same lens in everyone. ODs who take pride/care in their CL fits would cringe at that one-base-curve-fits-all mindset<emoji_u1f609.png> Fit based on k. That’s postop calculated ave k, not preop k, as that would make little sense
At a minimum I’d recommend having 2 BCs for flat and steep postop ks. We used to use 4 different BCs but dropped to 2 wo any big decrement in ideal fit
You’re going to have to experiment with Ks and BCs because there are other variables involved (eg diameter, lens thickness and material, etc). So I can’t give you any rules about Ks and BCs
But trust me–once you do an analysis and try to optimize BCL fit post ASA by matching Ks with BCs, you’ll realize better comfort, faster healing, and better vision, which should be intuitive
Of course if someone’s doing 90% LASIK and only a few PRKs per year, it’s probably not worth going to this much effort, as less than 50% of surgeons are using BCLs post-LASIK anyway, and these are coming out so soon (1-2 days) that fit is almost irrelevant
Back when I was doing LASIK I started using BCLs postop, as it did seem to lower my incidence of epi ingrowth, with the BCL perhaps pushing the flap down, serving as a guide so the epi grows across not down, and a reminder for pts not to rub. I’m curious what % of LASIK surgeons out there use BCLs on primary cases (everyone does on enhancements for these same reasons, so if the logic holds there, shouldn’t it hold for primary cases, as well?)
Thanks and looking forward to seeing many of you at ASCRS—

Emil William Chynn, MD, FACS, MBA

Harvard/Columbia/Dartmouth/NYU/Emory-trained
1st eye surgeon in NY to get LASIK himself (1999)
Performed 5,000 LASIKs from 1996-2002
Switched to non-invasive LASEK in 2003
Have performed more LASEKs than any MD in US

Cuastom lasik over correction

Q:

Kera-gurus:

I have a 52 year old guy who had Custom LASIK one month ago for myopic astigmatism (OD -3.00 + 0.25 and OS -3.25 + 1.25).  He is slightly overcorrected with refraction of +0.50 + 0.25 in each eye.  He’s doing fine for distance activities such as soccer and driving. But he is a little blurry watching TV and in the 5-20 foot range. He is fine using +2.50 readers for computer and near activities.

At this age and after this amount of treatment, is any regression likely to occur to bring him back closer to Plano?

Would the Contact lens and Acular treatment be at all useful this far out from surgery ?

Curious how others in the group would manage this?

Thanks as always for your expert advice,

Mike
Bellevue, WA

 

A:

Mike
Put him on diclofenac QID for a month. Will hit Plano. Stop when Plano. QID more effective than less frequent dosing. Works much better than Acular. CL isn’t necessary. Mechanism is Epi hyperplasia.
I’ve tried every NSAID over 15 years. Voltaren works best
I’m going to anticipate people saying QID dosing is risky and can cause a corneal melt. Simply not true. Wish that article never got published BC it’s prevented hundreds of MDs from treating thousands of pts like this safely BC of a bad batch of generic NSAID with a bad vehicle that’s no longer on the market and hasn’t been for a decade
How do I know? BC I’ve used NSAIDs to regress about 1,000 pts over the past 15 years w zero complications
Works better in ASA than w lasik. Can get up to 1 D regression in ASA. In lasik only .75 max. Must start therapy within a month postop or it doesn’t work very well. Can take up to 3 mos so need to be patient ie effect might be .25 D/yr. effect is permanent
If you guys think I should publish my results BC this modality isn’t widely known I’ll have my fellows do so
Hope this helps and good luck

Emil William Chynn, MD, FACS, MBA

Harvard/Columbia/Dartmouth/NYU/Emory-trained
1st eye surgeon in NY to get LASIK himself (1999)
Performed 5,000 LASIKs from 1996-2002
Switched to non-invasive LASEK in 2003
Have performed more LASEKs than any MD in US

PRK v LASEK

PRK vs LASEK
The basic difference has to do with the method of epithelial removal. In order of less cellular trauma, less inflammation, less pain and risk of scarring, and a cleaner bed, these are the generally recognized categories:
“Old-fashioned PRK” – mechanically removing the epithelium with a spatula or Amoilis brush etc. No attempt made to delaminate the epi. Basically you’re sandpapering or scraping off the epithelium, which kills millions of cells in situ, causing release of cytokines and other inflammatory mediators. It might look like you have “clean edges” at the scope afterwards, but that’s a misleading view that ignores how traumatic this is to the eye. Few high-volume surface ablation surgeons are doing this anymore, because there are better modalities. Most PRK surgeons limit their ablations to no more than -6 or -7 because they recognize the pain and scarring risk
LASEK – this is what was known as “alcohol-assisted PRK” a decade ago before it became clear it’s substantively different in terms of atraumatic and vastly less Postop pain and scarring. This was invented at MEEI in 2005 by 2 of my collaborators, Juan Carlos Abbad and Jon Talamo, and popularized and published by Dimitri Azar shortly thereafter. (The Wikipedia entry on this is wrong, but every time I correct the historical record the lay editor for refractive surgery changes it back so it’s wrong, so I gave up, which is one of the problems w wiki as they use lay editors not true experts in the field). Delamination of the epi allows for a very clean and atraumatic removal, hence less inflammation -> pain -> scarring. Most high-volume surface ablation surgeons are using this method, and many upwards revised their limits to -8 or -9 (if there’s sufficient residual corneal stroma)
Epi-LASIK or epi-LASEK are the same. I’ve tried to popularize the latter term with some success, since it’s obviously more similar to LASEK rather than LASIK. An EpiKeratome is used for the delamination. Avoiding alcohol avoids alcohol toxicity to the surrounding tissues, some of which is inevitable in LASEK even if you use a well. Years ago most practitioners (myself included) stopped replacing the epithelium as they found recovery to be faster this way. Yet it’s still less traumatic and inflammatory and has a faster recovery than even LASEK. With epi some surgeons are comfortable going up to -10.
I’ve done over 15,000 surface ablations at this point and always try with my fellows to improve our techniques and outcomes. We had a fellow from Venezuela come who had a PRK two years prior. He got to 20/20 but was in agony for 10 days. His dad is a MD and owns the largest private hospital in Venezuela so he got the procedure for free. After 1 year with me he flew up his entire family, parents, brothers, sisters to NYC to get LASEK or epiLASEK with me. They must have spent $20,000 on that in just airfare and hotels and laser fees (even though we did them close to cost). That should tell you that he really came to believe that LASEK is dramatically different and better than PRK, when they could have got that for free back home. None of them had any pain, and we got them all to 20/15
ASA is Advanced Surface Ablation and refers to LASEK and epiLASEK where the epi is delaminated, to distinguish them from non-advanced PRK, where it’s simply sandpapered or scraped away
Anyway, that’s my summary of current terminology as probably the most active practitioner of surface ablation in the US, for whatever it’s worth;)

ANIRIDIA tatoo

Q:

Dear Emyl
I´m thinking if is a good case for corneal tattoo this case ?
She is blind since child
I would like to know more details about your thecnique
What does it means  and how do you do
” injecting the ink orthogonal to the corneal surface using fine tattoo needles”
Thanks
A:
hi ronal

i think this would be a good case for several reasons:
1. it seems like a NLP eye, so there is no downside risk
2. brown eyes are easier to color match
3. the pathology is mostly posterior, eg there isn’t a huge pannus or band keratopathy which can inhibit ink uptake
4. the eye looks otherwise normal (ie normal-sized, not shrunken) so it will have a good cosmetic result
there are many other ways to do this, involving injecting ink with a needle into the stroma
i don’t like this approach, as it is difficult to precisely control the dispersion, even if you make some type of pocket
also then it’s impossible to make an iris, all you get is a black spot, which is better than white, but not great
i like to use a tattoo machine, there are many on the market that you can buy online for under $1000 all-included
make sure you choose one that has continuously variable oscillation/Hz, so you can go down below 10Hz for control
older/cheaper machines have too much initial starting resistance, so you if you try to go down on Hz, the unit stops
you also need good control of maximum extension, this helps avoid perforations (by giving more control)
it’s not like you can go down to less than the thickness of the cornea, actually
but i find that a lower travel length does help you control how deep you go, actually
i suppose this is why they have that control, as it probably helps you visually control depth in the skin
go with a 3-needle cluster, 1 needle takes forever and is very hard to get even coverage
more than 3 needles sacrifices quality for control
you can buy special ink with fine particulate size that has been centrifuged and the larger particles discarded
this is more expensive and hard to find, i haven’t noticed a huge benefit to doing so, only a small benefit
afterwards just put on a BCL and give some steroid QID, taper by 1 drop per week, plus an ABx BID x 1 wk
dc BCL at 1 week
if you have anterior pathology like bad band-k, for ex, you should remove the epi with EtOH like a LASEK and remove it
sometimes i use EDTA, sometime i add manual stripping/debridement, sometimes PTK, sometimes burr–depends on path
for this i don’t think you need any of those modalities, so you can even leave the epithelium on (although it will prob come off ie slough off as you do the tattoo, in which case you then should remove it cleanly with a LASEK EtOH trephenation)
i think there should be some pics and a video of some of my cases on my website below
if not, just google my name + “discovery channel” and “tattoo” and you can pull some relevant videos/pics up
should point out that i was first taught this technique by Doyle Stulting, MD  PhD while a Cornea Fellow at Emory in 1996
good luck, let me know how it goes, and perhaps post some nice pre/post pics on knet if so we can see how it goes
have a nice weekend, everyone!
emil

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