Different Doctors same machines

If you are thinking about having Lasik, IntraLasik, PRK, LASEK, Epi-Lasik, RLE, or P-IOL eye surgery, this is the forum to research your concerns or ask your questions.

Different Doctors same machines

Postby brownkc » Tue Jun 20, 2006 5:14 pm

How much of a role does the doctor play in the outcome of LASIK/PRK?

I have had consultations with 2 well-known eye doctors in the area and am having a third consult with a doctor recommended by a couple of coworkers. I am Myopic, -8 and -8.25, with a slight astigmatism of around -/+1 (I think it said negative). I'm 32 and my vision has been fairly steady for over 12 years.

During the first consult, I met with the doctor who would perform the procedure but got the feeling it was more like a factory for him and a coworker also had a questionable consult. Testing was minimal, vision and a manual cornea thickness test, and I was told I would likely be a good candidate.

The second doctor had a very high tech center and performed a specialized test (Orbscan II?) for cornea thickness and ran one wave scan test so I could see the types or abberations I currently have with contacts in. An assistant performed the tests and in consult with a staff doctor said they would recommend custom PRK because of the level of myopia. They own the equipment used by most physicians in the area. Follow up exams, would be performed by my normal eye physician not the second doctor. They work out of the same office for non-LASIK procedures.

The doctor I am visiting next week comes highly recommended by several coworkers, two of which have had LASIK performed there. The doctor has good credential and my personal eye doctor, whose practice is tied with the second doctor I visited, said that he has had several patients go to the third doctor with success and stated he was a good doctor. This doctors uses the equipment owned by the second doctor, charges about the same but is under my vision plan for a 20% discount. Hence the question, I have doctor #2's name more often than #3, they both use the same equipment and #3 would save me about $1000 so how much of a part does the doctor play in the surgery?
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Postby LasikExpert » Tue Jun 20, 2006 8:14 pm

The tools that your doctor uses are not nearly as important as the experience of the doctor who uses them. You need to focus on the best available doctor, rather than on which laser or the cost. You can own a Steinway piano but only be able pick out a tune with one finger. A talented musician can make even an inferior piano sound good.

You have described experiences with the three primary types of providers of refractive surgery. One is a large high-volume practice with little interaction with the surgeon. One is a smaller lower volume practice with much more interaction with the surgeon. One is comanagement with an optometrist for preoperative and postoperative care and controlled access to the surgeon. Each has its own advantages and disadvantages.

Some people don’t have a problem with the “mill” mentality that sometimes permeates a high volume practice. Some do not like an optometrist providing part of the surgery related care and want only staff directly under an ophthalmologist to be involved. Some require that the surgeon do just about all the work.

You can find equally excellent and equally poor outcomes in all three systems. If the quality of the surgeon is the same, which system is best for you is a matter personal choice. However, you must go where you are most comfortable and where you can place your trust. If you go where you have underlying concerns and something goes wrong, those concerns will balloon and trust in your doctor’s advice may be compromised – even if the doctor is correct. You want to choose the doctor you would seek in times of trouble, not just when everything goes as it should.

Nobody wants to pay more than required for anything, but you cannot make such a decision on price alone. If you go for price and something goes wrong, you may never forgive yourself. Go for the doctor with the best qualifications. If that happens to be the least expensive, then that is great news for you. If it is not affordable I recommend you do one of two things: 1) Ask the doctor you want if s/he will accept the price offered by the other surgeon. 2) Wait.

To help evaluate a potential doctor you may want to use our 50 Tough Questions For Your Lasik Doctor or consider a surgeon who has been evaluated by our organization at Approved Lasik Doctors.
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Postby brownkc » Wed Jun 28, 2006 4:22 pm

I have now visited all 3 clinics and am stuck between two. I am -8 and -8.25 w/ astigmatisms between .25 and .75. Both doctors will use the same equipment, Visx 4 (I believe), at the same treatment facility.

One is a well known doctor in town and one of two doctors most people relate to LASIK. I met with an assistant in my consult and after conferring with an onsite doctor and reviewing an orbscan, she said they would do PRK because it would provide more tissue (cornea) to work with if further corrections are needed and because of my nearsightedness. This doctor also tests equipment for the major manufacturers (Bausch & Lomb, etc). From what I can tell, the only time I will meet the doctor is during the procedure. Afterwards, I will be treated by my regular eye physician because they operate out of the same practice.

The second doctor is well established but not a name I heard until I started talking with coworkers about LASIK. I met with a LASIK consult who is also an Optician. After an orbscan, he recommended LASIK. After explaining the PRK recommendation, he stated that they are not comfortable performing PRK for myopia beyond 6-7 diopters. The orbscan gave a thickness at the thinnest point of about 530. They create a flap that is 120 microns thick and stated the amount ablated would be around 105 microns leaving a generous margin of error for correction of over 3 diopters. In addition the orbscan is also calibrated to underestimate by an 8% margin to avoid errors. He stated that the concern with higher diopters is hazing but couldn't explain why.

Is the level of correction possible with the same equipment different for LASIK and PRK? What are the acceptable levels of correction for PRK? What should I do or ask?
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Postby LasikExpert » Wed Jun 28, 2006 5:22 pm

There are good reasons to recommend Lask and to recommend PRK. Both have advantages and disadvantages in your case. There also are good reasons to recommend no surgery at all.

The cornea considers laser refractive surgery to be a wound and responds accordingly. A part of a normal wound response can be the formation of opaque white cells in the cornea. These cells block light and cause haze. Corneal haze normally does not occur unless the amount of correction is over about 6.00 diopters and haze normally occurs only with surface ablation techniques like PRK, LASEK, and Epi-Lasik.

The reason haze does not occur with Lasik and IntraLasik is because applying the laser energy under the Lasik flap “fools” the eye into not knowing it has had surgery. The wound response is therefore very different in Lasik and IntraLasik. This is also why vision recovery is normally very fast after Lasik and why there is usually no pain. If you have PRK, haze will be an issue. If you have Lasik haze will not be much of an issue at all.

At least 250 microns of corneal tissue must remain untouched for long-term stability. More is always better. If your cornea is actually 530 microns thick and the flap is actually 120 microns thick and the ablation is actually 105 microns, then you would have 305 microns of untouched tissue remaining. There are a lot of “actually”s there.

The Orbscan is very accurate at determining corneal thickness. I know of no study that would affirm the doctor’s eight percent off statement. If the Orbscan is eight percent off, then it needs to be recalibrated. Let’s assume it is not eight percent off and remove that eight percent. Your cornea is now actually 488 microns thick.

Mechanical microkeratomes used to create the Lasik flap are relatively accurate, but that relative amount can be off 15-25 microns. If the doctor uses a mechanical microkeratome and targets a 120 micron flap, the flap could actually be 145 microns thick.

A femtosecond laser microkeratome (IntraLasik) can make the Lasik flap with more accuracy, but even a laser created flap can vary by about 10 microns.

The amount of tissue to be removed is usually very accurate and is calculated by the laser if your surgery will be wavefront-guided, or is calculated by multiplying 12 microns for ever 1.00 diopter of correction if the optical ablation zone is 6.0mm. If the optical ablaion zone is larger than 6.0mm, then the ratio of microns removed for each diopter of correction is greater. At 7.0mm the ratio is about 18 microns for every 1.00 diopter of correction. Your doctor coming up with 105 microns (not 8.25 D x 12 microns = 99 microns) indicates that the doctor intends to use custom wavefront-guided ablation or that the ablation is conventional and larger than 6.0mm.

The one issue I have not heard anyone discuss is regression. With 8.25 D of correction, you will most certainly regress back toward the original refractive error. Regression of 1.00 – 1.50 diopters would be reasonable. Regression would require either initial overcorrection so you regress back to the desired plano (no refractive error), or you will need enhancement surgery to resolve regression. In either case, that means more tissue being removed. Somewhere between 12 and 20 microns more.
With all the variables included, you no longer have enough corneal tissue for Lasik or IntraLasik to be safe. You are simply getting too close to the required minimum. If the cornea is made too thin, it loses stability, bulges forward causing severe and irregular refractive error.

The surface ablation techniques of PRK, LASEK, and Epi-Lasik would not have the corneal thickness limitation because they do not use the Lasik flap. The problem with these techniques is that they raise the risk of corneal haze to a problematic level.

There are two methods to reduce the probability of corneal haze with a surface ablation technique. One is plain ol’ vitamin C. Taking 500mg of vitamin C twice a day for a week before surgery and at least two weeks after surgery, plus wearing 100% UVA, UVB sunglasses if you even think about going out into the sun, has been shown to reduce the incidence of corneal haze to just about nil. Additionally, the surgeon can apply Mitomycin C to the cornea immediately before applying the laser energy. Mitomycin C chemically changes the wound response and virtually eliminates the probability of haze. Mitomycin C is a rather strong medicine that is best avoided if possible, but is appropriate if necessary. In your case, it would probably be necessary.

If you do decide to have refractive surgery, do not expect the “20 Minute Miracle”. With your large refractive error it is reasonable to expect a period of time with poor vision while you regress and a high probability of needing enhancement surgery.

You should read:

Lasik and Pupil Size

Custom Wavefront Lasik

IntraLasik

LASEK

Epi-Lasik

If you are at or over age 40, you should read:

Sudden Presbyopia
Glenn Hagele
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Postby brownkc » Wed Jun 28, 2006 8:24 pm

Glenn,

Thanks for the information. The doctor that wants to perform PRK will use mitomycin. I called back to get their take on the difference of opinion. I asked how far he has gone with PRK before and the assistant said 11.5 and he has done hundreds if not over a thousand with my level of myopia and worse. I take that with a grain of salt.

As to later corrections, I have been told this may be necessary. The PRK doc includes it in their overall price and the LASIK doc charges $135 an eye for touch ups.

The 8% is supposedly a safety zone programmed by Bausch and Lomb. He claimed the software reports a thickness that is 8% less than actual thickness. So my cornea would actually be about 8% thicker than listed on the report. His guess was that B&L does this to reduce their liability if an aggressive doctor pushes the limit on ablation.

I believe I am going to go with the better known doctor and PRK. Even though they will use Mitomycin, would I improve the odds of no haze by taking the Vitamin C? My biking and driving sunglasses both block out UVA and UVB and I try to wear them as much as possible.
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Postby LasikExpert » Wed Jun 28, 2006 8:48 pm

Unless you have an allergy to vitamin C, taking 500mg twice a day for at least a week before surgery and at least two weeks after surgery can do no harm, and may do a lot of good.

I think the folks at B&L would argue those points about the Orbscan II, but your doctor may have found that his particular Orbscan underestimates actual corneal thickness. If I was in this conversation I would ask how the doctor determined that there is a difference. Did he use multiple pachymetry devices to compare? What pachymetry devices were used for compariston? How many patients? Was the study peer reviewed? Was it published?

As you can see, I take things with a grain of salt too.

You seem to be aware of the issues you face. Remember that the most you can achieve with refractive surgery is the convenience of a reduced need for corrective lenses. To achieve that convenience you must accept some risk. Only you can decide if the potential benefit is worth the potential risk, based upon your own values.

Please let us know how you do, if you decide to have surgery.
Glenn Hagele
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USAEyes

Lasik Info &
Lasik Doctor Certification

I am not a doctor.
LasikExpert
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Joined: Fri May 12, 2006 6:43 am
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