which of these machines...?

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which of these machines...?

Postby elspeth » Sat Mar 17, 2007 10:17 pm

Visx Star S4 IR with Wavescan - Excimer Laser
CustomVis Pulzar Z1 with iTracy - Solid State Laser

Wavelight allegretto

which of these machine lasers is best for an enhancement? to create a larger ablation area for oversized pupils
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Re: which of these machines...?

Postby LasikExpert » Sun Mar 18, 2007 3:11 am

elspeth wrote:Visx Star S4 IR with Wavescan - Excimer Laser


The optical ablation zone of the S4 is limited to 6.0mm in wavefront-guided mode, larger in conventional mode.

elspeth wrote:CustomVis Pulzar Z1 with iTracy - Solid State Laser


This laser is not FDA approved. I do not have information on this laser.

elspeth wrote:Wavelight allegretto


Optical ablation zone of the Allegretto in wavefront-guided mode is similar to the S4. Wavefront optimized mode is significantly larger.

elspeth wrote:...which of these machine lasers is best for an enhancement? to create a larger ablation area for oversized pupils


The laser recommend by a competent and trusted surgeon after an analysis of all the unique factors that are important to the predictability of your outcome and based upon the results of previous similar patients. There is no singular "best" laser. A good doctor knows the abilities and limits of his/her tools and will not attempt to exceed those limits.
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Re: which of these machines...?

Postby JPD » Tue Mar 20, 2007 4:27 am

LasikExpert wrote:
elspeth wrote:Visx Star S4 IR with Wavescan - Excimer Laser


The optical ablation zone of the S4 is limited to 6.0mm in wavefront-guided mode, larger in conventional mode.


Isn't that just the FDA approved number? Can't it go "off label", larger then that?
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Postby LasikExpert » Tue Mar 20, 2007 5:05 am

If a device is able to treat a different optical ablation zone it may be able to be done off-label, but it is my understanding that at this time wavefront-guided ablation is limited to 6.0mm or less.
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Postby JPD » Tue Mar 20, 2007 2:56 pm

LasikExpert wrote:If a device is able to treat a different optical ablation zone it may be able to be done off-label, but it is my understanding that at this time wavefront-guided ablation is limited to 6.0mm or less.


Really? Is that for all machines, Alcon, B&L and the rest?
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Postby elspeth » Tue Mar 20, 2007 9:51 pm

so i assume wavelight is the best of the 3? based on yr info given
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Postby LasikExpert » Wed Mar 21, 2007 1:39 am

It is my understanding that the WaveLight Allegretto is able to provide an optical ablation zone of up to 6.0mm in wavefront-guided mode. It may be able to treat a larger optical ablation zone in its conventional mode, which is wavefront optimized. It appears that in custom wavefront-guided mode, all the lasers mentioned have a similar limitation.

You may want to read about Wavefront Lasik.
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Postby JPD » Wed Mar 21, 2007 2:17 am

LasikExpert wrote:It is my understanding that the WaveLight Allegretto is able to provide an optical ablation zone of up to 6.0mm in wavefront-guided mode. It may be able to treat a larger optical ablation zone in its conventional mode, which is wavefront optimized. It appears that in custom wavefront-guided mode, all the lasers mentioned have a similar limitation.

You may want to read about Wavefront Lasik.


Very interesting. This brings up two question I now have. With this being the case, then why in a lot of the places I look do I commonly see the Visx getting bashed for having a small optical zone, while other lasers such as Alcon and B&L get praised? People are alway bragging about Alcon having an 8mm optical zone. I assume that must only be non-wavefront mode then? Two, how do people with large pupils get treated with a custom wavefront procedure? Or is it that people with large pupil's only get conventional Lasik procedures?

Thanks.
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Postby LasikExpert » Wed Mar 21, 2007 7:58 am

The optical ablation zone is the area fully corrected. The transition zone is the area from the optical ablation zone to the outer edge of the treatment area. The transition zone is a ring that is gradually less and less corrected until it meets the surface of the cornea. Transition zones are not custom wavefront-guided. The ablation zone is the entire area where tissue is removed, including optical and transition. Now add to this already confusing list of terms the zone that is wavefront-guided, and the concept of wavefront-optimized.

Some lasers are able to provide very large ablation zones, but the area that is custom wavefront-guided is still at 6.0mm.

If you read about Lasik pupil size issues, you will see that pupil size alone is a poor predictor of who will and who will not have night vision or similar problems. There appears to be many factors involved, including corneal curvature, depth of ablation, percentage of total cornea affected, angle of transition zone, on and on. There are people with naturally dilated pupils larger than their optical ablation zone who do not have night vision problems. It is just difficult to predict.
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Postby JPD » Wed Mar 21, 2007 3:14 pm

LasikExpert wrote:The optical ablation zone is the area fully corrected. The transition zone is the area from the optical ablation zone to the outer edge of the treatment area. The transition zone is a ring that is gradually less and less corrected until it meets the surface of the cornea. Transition zones are not custom wavefront-guided. The ablation zone is the entire area where tissue is removed, including optical and transition. Now add to this already confusing list of terms the zone that is wavefront-guided, and the concept of wavefront-optimized.

Some lasers are able to provide very large ablation zones, but the area that is custom wavefront-guided is still at 6.0mm.

If you read about Lasik pupil size issues, you will see that pupil size alone is a poor predictor of who will and who will not have night vision or similar problems. There appears to be many factors involved, including corneal curvature, depth of ablation, percentage of total cornea affected, angle of transition zone, on and on. There are people with naturally dilated pupils larger than their optical ablation zone who do not have night vision problems. It is just difficult to predict.


Thanks for the explination Glenn. I will try to keep this short as I don't want to beat this subject to death and force you keep revisiting it. I have a pretty good understanding in regard to optical zones, transition (or blend) zones, and the combined treatment zone. Even so, what I was asking about in my previous post was that I've seen the Visx listed as having a wavefront guided OZ of 6mm with a transition to 8mm. I've also seen most all other lasers listed as very similar to this. However, I never the less see many people bash the Visx for having a small optical zone and praise other lasers like the Alcon for having an 8mm OZ, not full treatment zone, but 8mm OZ with a blend out to like 10mm. I'm curious, is this just misinformation being spread around by people on the Internet? It seems to me from the information I've found is similar to what you've stated in that the Visx is very equivelant to all other lasers in this area. Am I correct, or is the Visx inferior in the area of optical zone, blend zone, and overall treatment? Is it considered a bad choice for people with large pupils?

Thanks Glenn, and I'll try to make this my last post on the subject.
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Postby DryEye » Wed Mar 21, 2007 4:05 pm

Why don't these machines provide a larger treatment zone(s)?
Is it bad for the structural integrity of the cornea to treat the outside edges of the cornea as they do the middle of the cornea?
Most I would imagine want that kind of treatment similar to a contact lens correction.
Thanks
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Postby elspeth » Wed Mar 21, 2007 9:53 pm

may i knw which laser out of the 3 i mentioned is the thinnest in diameter
thinnest = most accurate? coz its capable of pin point accuracy like a gun?
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Postby elspeth » Fri Mar 23, 2007 10:46 am

bump..... glenn pls help
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