I had LASIK in April and was very successful getting -10.75 down to -1.75 in both eyes. My vision has not regressed since then and today I found out that I'm a great candidate for enhancement. The bad news is that I do not have enough cornea tissue so my doctor said I had to have PRK done instead. What are your thoughts and case study experiences? What should I expect in terms of "pain" compared to the painless and fast experience of LASIK? Is this something that I should pursue or should I just leave it alone and remain at -1.75.

What is your uncorrected vision now(possible 20/70?) and if you wear glasses sometimes, what do you get with them? Also dont forget the presbyopia issue that occurs at middle age. Youd be taking a risk with PRK and may be trading up for reading glasses anyway. Having a little myopia goes a long way for presbyopia. I know what presbyopia is like, I have a little presbyopia and things become somewhat blurry from near with glasses so I always take them off to read or eat and I use my old glasses for the computer. Youd be able to do all that without glasses.

I would be very cautious about a PRK enhancement over LASIK surgery. In the past, the rule has always been "never zap a flap." That is, never perform PRK over LASIK, because the risk of significant central haze and scarring is just too high. Now, over the last two or three years, it has been found that a regimen of vitamin C (1000mg/day) for several weeks before and after the surgery, combined with intra-operative use of Mitomycin-C (2% ophthalmic solution), is very effective at minimizing haze formation in PRK over LASIK. That's the good news. The bad news is that MM-C is a toxic and dangerous drug with long-lasting effects. The long-term effects of MM-C as used in refractive surgery are unknown, but it is known that ocular tissue melt has occurred years after its use for other medical conditions in the eye (such as for pterygium). So, if your doctor figures to avert haze and scarring by using MM-C, I would want some serious, fact-based assurances as to why he thinks its long-term safety profile is acceptable. And if he doesn't plan on using MM-C, I would want to know how he plans to avert visually significant central haze and/or scarring. Most doctors feel that vitamin C by itself is not enough to prevent haze in PRK over LASIK.

Bryce Carlson

Oops! You missed that concentration by a bit. Mitomycin C (MMC) for refractive surgery is diluted to 0.02%, not 2%. The application type and time varies greatly from doctor to doctor. The range is a small sponge soaked in MMC and applied to the centeal portion of the cornea for two minutes down to the sponge wringed out to almost dry for 12 seconds.

You may know of a study that I have not found Bryce, but when applied to a healthy cornea without the presence of blood vessels and not touching any other portion of the eye, tissue melt does not normally occur.

MMC has been used for years on other parts of the body to promote wound healing without scar tissue and even against cancer, but its use in ophthalmology is somewhat recent. MMC is strong medicine that is appropriate when required, but may be best avoided when possible.

Glenn Hagele
http://www.USAEyes.org

I am not a doctor.

Yes, .02%, not 2%. My mistake. MMC is a toxic and dangerous antineoplastic drug. It certainly has its place in the pharmacopeia of modern medicine, but prophylactic use in an elective procedure such as PRK may not be that place. Late-onset scleral melt after use of MMC for ptergyium, for example, is well documented in the literature*. It is true that higher concentrations are often used for longer periods for ptergyium than for refractive surgery, but no truly safe dosage has been determined. When MMC is used prophylactically on a patient for refractive surgery, that patient is participating in a long-term experiment -- the results of which may not be known for years. The risks may very well be low, but, in my opinion, such risks are problematic in an elective procedure such as PRK.

* See, for example, http://bjo.bmjjournals.com/cgi/content/full/86/3/357

Bryce Carlson

Bryce,
Actually - many doctors like myself prefer PRK or LASEK to enhance LASIK. To say it another way - we now prefer to zap the flap. At the Seattle Summer Refractive Meeting last week, I presented the results of a retrospective review of cases of PRK or LASEK to enhance previous LASIK. Not only were the results excellent - the rate of haze in this review was 0%. Of course - I know haze can occur - so this just tells us that the risk of haze for surface laser over a flap is low - probably less than 1%. In my review - only 14% of cases used MMC. I have submitted this review for publication (JCRS).
As well, more than 30% of eyes had improvement of best-corrected vision. This improvement appears to be related to smoothing of mild microstriae.
Dr. Dick Lindstrom mentioned that he also uses this technque alot - because it avoids the risk of epi-ingrowth - which occurs in 3% of flap lift enhancements in his practice.
I currently use MMC 0.02% for most of my LASEK to enhacne LASIK cases - because MMC has been found to be safe when used at the right concentration for a short period of time. I use it for only 12 seconds.
So - we avoid epi-ingrowth (and also flap straie and other problems) and get improvement of best corrected vision in a percentage of cases when performing LASEK to enhance previous LASIK.

I hope this helps

Bill Trattler, MD
Miami, FL

Bill and Bryce,

Not to jump into the middle of the fray, but it appears from my vantage point that you are both correct.

Current knowledge of the use of MMC for the prevention (not treatment) of corneal haze has provided good short and medium-term results and MMC is commonly used for this purpose. Equally, the use of MMC on the cornea does not have the advantage of long-term studies to determine if in 5, 10, or 20 years MMC will be a detriment to the cornea.

This really is not a unique situation. Everything that is “new” in medicine is also “unproven” for the long term. At least, unproven until years of use have past. What doctors, researchers, and technicians have always done, and probably always will, is look at how something reacts in animal studies (rabbit eyes were extensively studied for MMC), how a technique or substance worked on other parts of the body (MMC has been used to promote healing without scaring for years) and make an educated assumption of the value of the technique. Remember, this is medicine, not science. There are no absolutes.

Glenn Hagele
http://www.USAEyes.org

I am not a doctor.

Everyone who knows you, Dr. Trattler, knows you are a skilled, caring doctor who provides excellent care for his patients, and I certainly wouldn't second-guess your clinical judgment. However, you stated above that "I currently use MMC .02% for most of my LASEK to enhance LASIK cases -- because MMC has been found to be safe when used at the right concentration for a short period of time. I use it for only 12 seconds." Now, the 2001 study which I cited, above, showed a rate of approximately 1 in 100 cases of vision-threatening scleral melt when .02% MMC was used in ptergyium surgery for 3 minutes, and the surgeons involved in the study concluded that "all ophthalmologists should be aware of the possibility of vision-threatening complications and avoid routine and broad use of Mitomycin C in all fields." You indicate you use .02% MMC for only about 12 seconds, rather than 3 minutes, so the risk of ocular tissue melt is obviously much lower than the 1 in 100 incidence found in the study, but you have publicly stated that you discontinued your LASIK practice (in favor of PRK/LASEK) because of only two incidences of iatrogenic ectasia in patients with no known risk factors for it. Now, everyone agrees that in competent hands LASIK is both "safe and effective," yet you abandoned it because of a complication rate of unavoidable iatrogenic ectasia of about 1 in 10,000. Ocular tissue melt is certainly every bit as serious and vision threatening as ectasia, yet you are willing to take a very small risk of ocular tissue melt with MMC, but not ectasia with LASIK. Why is that? Why is the remote risk of one catastrophic vision-threatening complication to be preferred over another? Personally, I would take my chances with LASIK over LASEK with MMC any day.

Bryce

Bryce. I perform pterygium surgery with MMC as well. Let me explain the difference.
If you place MMC on the sclera - you can get a scleral melt because there is damage to the blood vessels from the MMC. As well, with pterygium surgery, we use cautery to stop bleeding from the conjunctival vessels. So it is the combo of custery and MMC that can lead to hypoxia and vessel loss - and thus a scleral melt.
As you know - there are no blood vessels on the cornea. Thus - there are no melts of the cornea from MMC. I am aware of just one melt - where the patient was prescribed MMC for 3-4 months on a 4 times a day regimen. But there have been no reports of melts with the use of MMC for 120 seconds, or evem 12 seconds (I prefer the latter time).
So bottomline - the risk of a melt with the proper use of MMC is as close to 0% as we know.

I hope this helps

Bill Trattler, MD
Miami, FL

Thanks for your reply, Dr. Trattler. I understand what you are saying; however, as an antineoplastic, in addition to the effects you mentioned, MMC also produces long-term disruption of cellular DNA and RNA in cells that come in contact with it, or are progeny of cells that come in contact with it. This DNA/RNA disruption process figures into MMC's ability to produce tissue melt or necrosis long after its use is discontinued. In addition, if MMC is as safe as you believe it to be, why did the authors of the MMC study I referenced specifically warn that "ALL ophthalmologists should be aware of the possibility of vision-threatening complications and AVOID routine and broad use of Mitomycin-C in ALL FIELDS"? In other words, if MMC is safe for routine use in fields such as refractive surgery, why did the authors specifically warn ophthalmologists in "all fields" to be wary of its use?

Bryce

Bryce,
There is a big difference between using MMC on a vascular area (like the sclera) and using it on an avascular area (like the cornea). For example - when using MMC for glaucoma surgery, the MMC causes a loss of blood vessels. This can be seen as an "avascular bleb". Similarly, with pterygium surgery, the MMC helps reduce regrowth of vascular tissue (the pterygium). The recurrence rate of pterygium surgery without MMC is thought to be about 50% - but this is reduced to 5% with MMC. I use MMC on every pterygium case. I have never had a melt, but I also do not cauterize the surrounding blood vessels - which may be part of the problem.
Back to the cornea - experimental studies on the cornea have shown that the biggest risk of MMC is on the endothelium - where extremely high concentrations can cause corneal edema.
When used in the correct concentration for the correct amount of exposure - there have been no reports of adverse problems. And I can definitely say that if there were problems - they would be disccussed and reported.
Again - the use of MMC is completely different and of a completely different purpose than the use of MMC for haze prevention.

I hope this helps

If there are reports that I have missed - please let me know.

Bill Trattler, MD
Miami, FL

Thanks, again, for taking the time to reply to my questions in such detail, Dr. Trattler. Again, I understand what you are saying. You believe that appropriate prophylactic use of MMC in PRK/LASEK surgery is safe and effective. I think you're probably right. But LASIK is also safe and effective, yet because there remains a remote risk of unavoidable iatrogenic ectasia in properly screened LASIK patients, you have abandoned LASIK in favor of PRK/LASEK. You do not believe MMC represents a similar remote risk of serious complications in LASEK/PRK, so, unlike LASIK, you are comfortable with its use. Perhaps, you are right. However, I might point out that one well-respected Canadian refractive-surgery chain includes the following information in their informed consent document, which must be read and signed by all prospective patients: "I understand that I am a candidate for PRK surgery. A compound called Mitomycin-C (MMC) may be used in patients undergoing PRK surgery. MMC is known to modulate would healing and significantly reduce the risk of haze or scarring after PRK. Clinical studies and our own results have shown MMC to be safe in the short-term post PRK surgery, with no complications reported to date. However, theoretically, there may exist a remote risk of thinning, and in rare cases perforation, of the cornea in the long term. I recognize that the use of MMC in PRK surgery is experimental, and while the short-term results are good, the long-term results and safety are unknown." In other words, this refractive-surgery practice believes the prophylactic use of MMC in PRK is "experimental," with "unknown long-term safety," and it may expose the patient to the remote risk of serious complications, such as corneal thinning and perforation. Obviously, Dr. Trattler, you do not agree with these doctors concerning the risk of MMC in PRK surgery. You may be right. You may not be. We'll know in about 10 years.

Bryce

Ectasia following LASIK in eyes with out preoperative risk factors is not the only reason why I stopped LASIK and switched to surface ablation. I prefer surface ablation for my patients because I think the quality of vision is better - as there is no chance of microstriae. Marguerite McDonald's study with the early version of Alcon Custom laser showed clearly that surface ablation (PRK at the time) resulted in superior outcomes compared to LASIK.
I want to make this perfectly clear. I am not saying that LASIK is not a good procedure. Many doctors who I highly respect prefer LASIK for their patients for the faster visual recovery. But I prefer surface ablation for my patients for the potential for superior quality of vision and the avoidance of immediate intraoperative complications (buttonholes, epi sloughs, poor flaps) and the avoidance of early and late issues (flap striae, epi ingrowth, DLK, ectasia, etc)
Again - no surgery is risk free - and clearly outcomes in 2005 are even better than in the past for both LASIK and surface ablation. Intralase technology has improved the safety of LASIK, and also has improved the quality of flaps. Of course - intralase does not avoid the issue of ectasia, which can still occur.
Of note - Dr. Lindstrom and Hardten have reported a risk of only 1 in 20,000 of eyes with normal preop topographies who have progessed to ectasia. In our series - the rate was higher.

I hope this helps

Bill Trattler, MD
Miami, FL

Thanks for sharing your expertise, Dr. Trattler. I really appreciate it.

Bryce Carlson

Very compliments for the great discussion you made and thank you for your advices, dr Trattler. I needed it for a patient of mine I have to do enhancement.

Antonio Pascotto
Ophthalmologist
Naples, Italy

PS - Sorry for my poor english... :)

Doctor, can you tell me more about the case you referred to in your below response involving corneal melting from the use of MMC? I'm very interested. Thanks.

>Bryce. I perform pterygium surgery with MMC
>as well. Let me explain the
>difference.If you place MMC on the
>sclera - you can get a
>scleral melt because there is damage
>to the blood vessels from the
>MMC. As well, with pterygium surgery,
>we use cautery to stop bleeding
>from the conjunctival vessels. So it
>is the combo of custery and
>MMC that can lead to hypoxia
>and vessel loss - and thus
>a scleral melt. As
>you know - there are no
>blood vessels on the cornea. Thus
>- there are no melts of
>the cornea from MMC. I
>am aware of just one melt
>- where the patient was prescribed
>MMC for 3-4 months on a
>4 times a day regimen.
>But there have been no reports
>of melts with the use of
>MMC for 120 seconds, or evem
>12 seconds (I prefer the latter
>time). So bottomline -
>the risk of a melt with
>the proper use of MMC is
>as close to 0% as we
>know.

>I hope this helps

>Bill Trattler, MDMiami, FL

Dr. Trattler, can you tell me more about the case you mentioned in one of your e-mail responses regarding the one case of corneal melting you're aware of due to the use of MMC? I'm very interested. Thanks.

Successful LASIK 8 years ago..blind as a bat and was extremely happy. Was severely nearsighted and had astigmatism. Eyes corrected. Ecstatic.
Fast forward right eye had regressed to 20/200, had some problems with distance and no problems with close up vision reading or just looking in the mirrow and putting on makeup. Went to doctor to discuss options..didn't want to wear an "occassional" contact in that eye because after wearing them for 20 years never wanted to do it again. Didn't want glasses either...Dr said I wasn't a candidate for LASIK and actually cancelled the procedure while I was at the laser center. Felt relieved he didn't go ahead just to do it. Months went by, vision is always fairly good in summer (extened daylight hours). Decided to postpone any surgery. Dr talked with colleagues said he could do PRK, said I might need reading glasses in the future, but I would see even better! Procedure done 2 weeks ago and I can't stop crying, every day I am so sorry I did this...can't focus. (Sorry if there are misspelled words while typing this...difficult to see computer keyboard) I would never have given up the clear crisp edges in my visual field within 15 feet. Now I can only see clearly out of both eyes at a distance. Putting on makeup is a struggle, looking in a mirror at 3 feet my face is blurry. Cups in cabinet are blurry, items on desk are blurry. I'm sick about this....did I sacrifice my close up vision for distance? God I hope not...It has been two weeks will this get better? My dr thinks I'm "overreacting". All I know is what I have LOST, the gain was not worth it. I pray every night that when I wake up it will be better and since going off the steroid drops 4 days ago, I can see my right hand clearly at a distance, whereas before it was a blob. Reading and writing is my greatest pleasure....THE WALL STREET JOURNAL is piling up. I hate even trying to read. please someone tell me that this is going to get better. I feel like I can't talk to my dr anymore, that is doesn't understand why I am traumatized.