Dr. Clark Chang on Corneal Cross-Linking & Optometry: What, When, How

Discussion in 'ODwire.org TV & Radio' started by AdminWolf, Oct 2, 2018.

  1. #1 Oct 2, 2018
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    AdminWolf

    AdminWolf Site Administrator & Tech Lead
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    At the AOA's 2018 annual meeting in Denver, CO, I caught up with @Clark Y Chang as part of the J&J Vision's InSight Studio.

    We talked at a bit about Corneal Cross-Linking -- what it is, why it's important, and critically -- WHEN TO REFER OUT for cross-linking. (The incidence of KCN was much higher than I had thought -- one critical thing I learned off the bat!)


    First -- the basics. What Corneal Cross-Linking (CXL) is:




    Next -
    Why this should matter to ODs, and how you can impact the course of the disease --





    Finally, when you should refer out, and what the patient can expect:



    Feel free to comment in this thread!!

    Adam

    (and thanks again to J&J Vision for giving me the latitude to talk about whatever I felt like with the interviewees! Just wait until I post the chats with Gretchyn and Art Epstein...)


    More InSight Studio Interviews ....
     
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  2. AdminWolf

    AdminWolf Site Administrator & Tech Lead
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    Thanks again to Clark for taking the time sit down with me! I hope we can talk him into giving a talk at CEwire2019 -- his knowledge about KCN seems a mile-deep.

    The shocking stat from the videos, to me, is that the incidence of the disease could be closer to 1 in 25 than 1 in 2000 (!!)
     
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  3. Lloyd Pate

    Lloyd Pate Well-Known Member

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    Send to



    Am J Ophthalmol. 2017 Mar;175:169-172. doi: 10.1016/j.ajo.2016.12.015. Epub 2016 Dec 28.
    Age-specific Incidence and Prevalence of Keratoconus: A Nationwide Registration Study.
    Godefrooij DA1, de Wit GA2, Uiterwaal CS3, Imhof SM4, Wisse RP4.
    Author information

    Abstract
    PURPOSE:
    To determine the age-specific incidence and prevalence of keratoconus in the modern era of diagnostics.

    DESIGN:
    Epidemiologic study.

    PARTICIPANTS:
    Total of 4.4 million patients from a mandatory health insurance database.

    METHODS:
    Data were extracted from the largest health insurance provider in the Netherlands. Patients aged 10-40 years were defined as the relevant age category for newly diagnosed keratoconus and the annual incidence of newly diagnosed keratoconus was determined. The prevalence of keratoconus was estimated based on the annual incidence, mean age at diagnosis, and average life expectancy. Main outcome measure was the annual incidence and prevalence of keratoconus.

    RESULTS:
    The annual incidence of keratoconus was 1:7500 in the relevant age category (13.3 cases per 100 000, 95% confidence interval [CI]: 11.6-15.2) and the estimated prevalence of keratoconus in the general population was 1:375 (265 cases per 100 000, 95% CI: 260-270). These values are 5-fold to 10-fold higher than previously reported values in population studies. The mean age at diagnosis was 28.3 years and 60.6% of diagnosed patients were male.

    CONCLUSIONS:
    Both the annual incidence and the prevalence of keratoconus were 5-fold to 10-fold higher than previously reported.

    Copyright © 2016 Elsevier Inc. All rights reserved.

    PMID:

    28039037

    DOI:

    10.1016/j.ajo.2016.12.015
     
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  4. Gretchyn Bailey

    Gretchyn Bailey ODwire.org Supporting Member

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    Love me some Clark Chang! He is a great speaker...very informal, very tuned into the audience, and very knowledgeable.
     
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  5. Frederick Frost

    Frederick Frost ODwire.org Supporting Member

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    Dr. Chang did not mention actually when to refer for cross-linking.

    I would feel with an initial diagnosis of Keratoconus at any point after that there could be a referral for cross-linking. Thoughts?
     
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  6. AdminWolf

    AdminWolf Site Administrator & Tech Lead
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    It sounds like he is able to perform the procedure himself (under supervision), so his situation is definitely different than most.

    Does it make sense to refer almost immediately once you've made the diagnosis? IE, how early do you perform a surgical intervention?
     
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  7. Frederick Frost

    Frederick Frost ODwire.org Supporting Member

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    I don’t have Dr. Chang’s expertise or experience but based on my reading unless there is a contraindication to cross-linking, I would think as soon as you have a diagnosis you would want to have the procedure done to prevent progression.

    Has anyone had a patient with sub clinical Keratoconus treated?
     
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  8. AdminWolf

    AdminWolf Site Administrator & Tech Lead
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    I would think a lot of people have until this point missed sub-clinical KCN. But now that there are therapeutic interventions, does it make sense to do something like screen people with a Pentacam or OCT if you have one at your disposal?
     
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  9. Richard Pagan

    Richard Pagan ODwire.org Supporting Member

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    lots of mild/moderate cones don't want to undergo surgery for something they can readily tolerate. I don't blame them, and I'm almost positive I wouldn't opt for surgery either. Especially when a large majority can achieve excellent vision with scleral lens. Not surprisingly the 20/40-20/50 threshold seems to be the tipping point.
     
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  10. Frederick Frost

    Frederick Frost ODwire.org Supporting Member

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    Unexplained reduced acuity will definitely get a topography in my office and sometimes in an OCT if indicated.
     
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  11. Richard Pagan

    Richard Pagan ODwire.org Supporting Member

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    I find topo is the highest yield by far for reduced bcva in younger patients
     
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  12. Lloyd Pate

    Lloyd Pate Well-Known Member

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    You do not want to refer too soon. I have seen numerous cross linking cases where the therapeutic effect keeps progressing years after treatment.
     
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  13. Frederick Frost

    Frederick Frost ODwire.org Supporting Member

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    Thanks for posting your experience. What do you do Lloyd? Do you look for a certain intervals of progressing ectasia before you making the referral? Thanks.

    Do you see actual increased irregularity with cases that do not go well? Are they all epi off? Have you seen any Epi on?
     
  14. Lloyd Pate

    Lloyd Pate Well-Known Member

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    You look for progression and poor BVA. You can just watch a stable cone with good BVA.

    They are all epi off. There is no more irregularity, the cornea just keeps flattening until you are scared they will become a hyperope.
     
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  15. Gretchyn Bailey

    Gretchyn Bailey ODwire.org Supporting Member

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    The company is considering epi-on treatment which will pave the way for ODs. Removing the epi is the sticking point for optometry.
     
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  16. AdminWolf

    AdminWolf Site Administrator & Tech Lead
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  17. Clark Y Chang

    Clark Y Chang Director of Specialty Lens, Wills Eye - Cornea

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    Thanks for the interview, Dr. Farkas. I may have been a tad too excited about this interview - can I blame on caffeine? =)
     
  18. Clark Y Chang

    Clark Y Chang Director of Specialty Lens, Wills Eye - Cornea

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    Thank you, Gretchyn! Much appreciated.
     
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  19. Clark Y Chang

    Clark Y Chang Director of Specialty Lens, Wills Eye - Cornea

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    Dr. Frost:
    Thank you for raising this interesting question on timing of referral for CXL consultation. This is an important question as this may be the first line of defense against potential loss of vision/visual functions for our KC patients. So if a clinician wishes to take a more conservative stance by observing on-label indications, then patients should be educated on CXL at the first sign of disease progression.

    However, many clinicians have gone beyond this basic guideline given the safety profile demonstrated with CXL. So this take us to a risk calculation management approach. We know that KC is likely to progress with increased overall disease severity with early onset forms of KC. Therefore, some experts have proposed looking at a risk score type of analysis in a young KC patient even if no recent records of progression. ie, age, current disease severity, presence of eye rubbing/allergy/atopy...etc. If risk of progression is high, then under this risk scoring analysis, then many clinicians will choose to treat with CXL - this is the scenario where some physicians will treat an emerging KC who may not yet be visually symptomatic.
     
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  20. Clark Y Chang

    Clark Y Chang Director of Specialty Lens, Wills Eye - Cornea

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    Dr. Pate:

    As per my previous posted reply to Dr. Frost, different treatment decision processes are currently evolving for CXL. In the more conservative approach, I agree that many ECPs look for declining BCVA as a associated symptom of progression. The hope is that if this is the approach taken, then tolerance for how much VA is lost prior to treatment is a very tight one and also ideally monitor patients very closely before pachmetry becomes a potentially limiting factor to treatment. CXL has the potential of bringing about a treatment result where patients preserve the best possible visual quality, so no doubt that treatment criteria will continue to evolve. In terms of the flattening effect, limited number of long term studies of 5 to 10 years show that flattening is not statistically significant after 4 years, but I have seen a case report where continual flattening was seen up to 9 years although with no significant refractive effects. I also have many KC patients who present with hyperopia/irregular astigmatism at baseline, and therefore, I don't emphasize the end point refractive error patients will achieve with the current iteration of CXL protocol (future protocol will change this). And as long as patients are well managed with contact lenses (or glasses in some cases), I have not had patient management challenges regarding refractive error changes after CXL. Than you for sharing your experiences, it is great to know that colleagues such as yourself are actively helping KC patients with providing them with the most updated management options.