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Post Info TOPIC: PRK With X Linking


Phase Two

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Date: Mon Jul 9 3:43 PM, 2007
PRK With X Linking
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PRK after UVA induced collagen crosslinking yields gratifying results
Dr. Kanellopoulos, Vegas 01.04.2007


Patients with keratoconus, post-LASIK ectasia could be effectively rehabilitated, surgeon says


• Modern Medicine


www.modernmedicine.com/modernmedicine/article/articleDetail.jsp?id=418308

• Ophthalmology Times




An alternative Treatment for Keratoconus
January 2007


An Alternative Treatment for Keratoconus
Collagen cross-linking with ultraviolet A light and riboflavin followed by customized topography-guided PRK may be an alternative to penetrating keratoplasty.
By A. John Kanellopoulos, MD


www.crstoday.com/PDF%20Articles/0107/CRST0107_09.php


An alternative Treatment for Keratoconus
January 2007


Pdf





-- Edited by QuintriX at 23:49, 2007-07-30

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Date: Thu Nov 8 8:34 PM, 2007
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I think the PRK with x-linking sounds really interesting.

I have always thought laser or similar “cutting” techniques combined with keratoconus eyes are a "no-go". What risks are involved when doing PRK on a KC patient? I mean, doesn't PRK or similar “cutting” techniques involve a lot of unwanted mechanical stress on a KC cornea and cause further acceleration of keratoconus? What do experts say about this?


Best regards, Jan

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Date: Fri Nov 9 1:27 AM, 2007
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This years Congress will be presented with this method, there is five years of follow ups.

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Executive

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Date: Mon Nov 12 1:42 PM, 2007
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Hi Jan,
as far as I know a) the combination PRK + x_linking was concieved by Theo Seiler (I may be wrong) b) there is no the same cut of the corneal layers as in Lasik therefore the corneal integrity is not disturbed in the same way as with Lasik c) I can not tell you what exactely the PRK is d) the PRK post op is very much like X_linkign post op (epithelial recovery, oedema, apopthosis, haze....)

Meanwhile I have some questions on the PRk itself. The wikipedia arfticle is not so bad but there is no realy the details of the technique. http://en.wikipedia.org/wiki/Photorefractive_keratectomy
When we read
"Because PRK does not create a permanent flap in the deeper corneal layers (the LASIK procedure involves a mechanical microkeratome using a metal blade or a femtosecond laser microkeratome to create a 'flap' out of the outer cornea), the cornea's structural integrity is less altered by PRK." or when we read "Unlike LASIK, PRK does not create the risk of dislocated corneal flaps which may occur (especially with trauma), at any time after LASIK."

one may ask 1) what is " the flap" 2) what exactly the PRK consist in?

What is the "No Touch" technique they talk about here
"An evolved form of PRK is called No Touch laser vision correction. It also treats the surface of the cornea but unlike other techniques, requires no assistance from manual surgical instruments. It is the only technique to use exclusively an excimer laser from start to finish.[citation needed]"
There are some more interesting information in this article.

On the other hand we have some contradictory information about the stand alone PRK wrt to KC:

1. all is good

all is good results

2. one is bad

one is bad


Overall, I'd like to have more detailed information on this procedure. Does anybody have articles about it? What does it consist in exactly?

For the curious, I found some interesting theoretical insights in to the corneal structure and thus possible causes of the post LAsik ectasia. Look here
interesting insights

Thanks

-- Edited by Yarsky at 15:33, 2007-11-12

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yarsky


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Date: Tue Nov 13 1:43 AM, 2007
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Hello Yarsky.

I think you are reading some interesting stuff about the PRK technique and furthermore at the customized treatment for kc people like us: the topography guided PRK treatment.

I would like to say that with the PRK it is difficult to have an ectasia at the cornea.This happens because of what you said above and also because the PRK is just reshaping the bowmans membrane-layer.Also,Dr K is doing two things.CROSSLINKING AND THE TOPOGRAPHY GUIDED PRK.Not only the topography guided PRK,but the xlinking procedure combinded together.

That is very important and crucial Yarsky and most people have lack of knoweldge in that.

With the LASIK technique this layer(Bowmans) is VAPORIZED.Imagine that...

With PRK we have only a gently reshape.Not doing anything else,such as flaps,microkeratomus,or destroying layers.

Moreover,with the cutting edge PRK lasers such as Wavefront Allegretto the laser is being applied with A FLYING SPOT BEAM.That is also crucial Yarsky.The flying spot technology.

Previous years this equipment and technology never existed for someone to use.People should know that.We are talking about technology how has developed but we need to use it in action.Not only saying things about technology.I benefit from this treatment so you people if you are candidates you are able to perform the treatment.

Before crosslinking we need to give a better shape at the cornea.Then we xlinking the cornea and thats an Holistic treatment for me and i believe for you.

Best Wishes,

-- Edited by Zeus at 02:16, 2007-11-13

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Executive

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Date: Tue Nov 13 9:52 AM, 2007
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hi Zeus, thanks!
Reshaping the Bowman's layer you say? Interesting! I nevertheless am looking for detailed technical articles describing the PRK itself. Does anyone have that?
On the other hand, Zeus, you say - 1st PRK (reshaping) than x_linking (fixing of the reshaped). As you know, i did x_linking some years ago. Can i do PRK now? Will it be a good idea to do the second x_linking afterwards? What is your opinion?


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yarsky


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Date: Tue Nov 13 11:31 AM, 2007
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I am wondering if x-linking and prk is an option for moderate kc plus cataract...i was thinking of looking into that option[asking at the wellington eye clinic about c3r to deal with the moderate kc in left eye and prk to deal with needing -9 rgp...

.in other words as my vision due to the kc with glasses is at best first and third letter on the chart but at worst 20/40 with piggybacks and up to 20/25 with piggyback..so even if my kc does not get worse[and c3r stops me worrying about needing a graft in 10-15 years time] i will still be in need of visual correction...i would still be half blind

problems are..i have shaddow cataract, corneal opacity/ scarring [according to my opticien[ and a history of corneal oedema due to kc [according to my eye specialist]and shaddow cataract[ which is partly why i would need visual correction..i would probably be shortsighted even if i did not have cataract or kc ] ...would prk be able to deal with those issues???

I have some bits of good news
1: I don't need a graft[so scarring etc must not be that bad]
2: the kc in that eye is stable or only progressing very slowly
3: i have not had hydrops in that eye

Are hard contacts the only treatment option for moderate kc with scarring? that correct vision..? c3r sounds great but won't correct my vision..and like i said i probably need visiual correction....i will almost certainly need my piggybacks after c3r anyway

Any advice..is lasik, prk, lasek or keraform an option after c3r when there has being scarring and an early cataract present

thanks


-- Edited by Geraldine at 11:34, 2007-11-13

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Executive

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Date: Tue Nov 13 1:00 PM, 2007
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Hi Geraldine!

I think the following. To do PRk and x_linking on a cornea, the cornea must satsify some criteria:
1. thikness 2. morphology, something else probably. First because I believe that these refractive procedures have their limits of correction. Imagine a very deformed cornea. PRK acts immediatly on the so-called Bowman's layer, a dense compact of collagene fiberes of say 10 µm (Bowman layer) of corneal thickness, immediatley under the epithelium. This layer is, thus, deformed, due to KC. The laser smoothes ("vaporizes") a part of this layer to compensate for the deformation. If it is too deformed one would probably need to smooth away the whole layer (at a certain point or zone) thus leaving the stroma open, structurally compromised again...And if cornea is thin besides that, x_linking will be a bit less effective...Anyway I think that the earlier one does all this the better are the results. You need always go to a specialst to find the precise answers.

Regards,Y.

PS. Here is an interesting article on Lasik procedure: I had shivers when I read it. I've got what "the flap" is; try to see the difference between the LASIk and PRK smile.gif
Wikipedia LASIK

-- Edited by Yarsky at 13:07, 2007-11-13

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