According to the doctors I've recently visited, a software upgrade has recently been issued to Star3 lasers to allow blending zones out to 8mm. As you can guess, I have 8mm eyes myself, and I'm *very* concerned about halos after getting the surgery. Is there any information on whether this upgrade has helped the problem? All other factors (ie. the doctor) being equal, am I better off with a different laser brand like B&L?

Thanks!

Not familiar with the Visx Star laser. However, if you have 8 mm pupils, you need an OPTICAL zone, not a blending zone of 8 mm. (the blending zone is always larger than the optical zone). Also, how nearsighted you are also affects night vision glare/halos postop. You are more at risk for these problems if you're a -8.00 than a
-2.00. At EmoryVision one of our lasers is an Autonomous, which we can go out to an 8 mm optical zone with and we haven't had problems with large pupil patients using this. As I said, don't know about the Visx. Perhaps another physician who uses this laser can answer your question.

Steven Corwin, MD
EmoryVision
Atlanta, GA

Peter,
I agree with Dr. Corwin. I use a VISX S3, and I would not perform LASIK on patients with 8.0mm pupil size, even with the new software. In fact, 2 such patients came in this week, and I explaing LASIK was not appopriate for them at this time. Their problem was not just the large pupils, as I have access to the autonomous laser which could potentially be used. They had high myopia, and it turns out that for a given level of myopia, the larger the optical zone, the more cornea needs to be removed - and their corneas were not thick enough to have LASIK and the large optical zone treatment.
But I get ahead of myself. As Dr. Corwin explained, the optical zone is the key for reducing or preventing serious night time vision problems. The new VISX transition zone was FDA approved, but it has not been shown to reduce night time problems in patients with very large pupil like yourself. It may help some, but there have been no published reports that have shown that it is safe for patients with 8.0 mm pupils. So I personally would not perform LASIK with the VISX laser on patients with 8.0mm or larger pupils. There are plenty of patients out there who can tell you how horrible their vision is due to having large pupils and smaller optical zones.
Now - when the optical zone is enlarge, more cornea needs to be removed per diopter of myopia. So for example - a patient with 5 diopters of myopia treatment- the VISX 6.5 mm optical zone would remove about 80 microns, while the autonomous 8.0mm optical zone would remove about 105 microns. There are certain rules for how much cornea can be removed for an individual patient, and this is related to their corneal thickness. My patients had 8 and 10 diopters of myopia, and thin corneas, so they could not have LASIK.
You may want to call Dr. Corwin if he is in your area (his office information is listed in the doctor directory). He is very knowledgeable about LASIK and would be helpful as you try to figure out whether LASIK is right for you.
I wish you the best of luck

Bill Trattler, MD
Miami, FL

Wow. Thanks for the quick responses. They are definitely different from what I've been hearing from the 3 doctors around Atlanta I've visited, who all seem secure that 8mm eyes are perfectly fine with Visx, especially with the s/w upgrade. I now have a feeling they were telling me what they needed to to get my business.

>Also, how nearsighted you
>are also affects night vision glare/halos
>postop. You are more at
>risk for these problems if you're
>a -8.00 than a -2.00.

As a quick background, I'm a -5.75R and a -6.00L, with -1.25 astigmatism in both. Dr Trattler mentioned corneal thickness, which I have 554R and 567L (if that's what "pachymetry" means on a eye chart). I was told, again by these same doctors, that this was above normal thickness.

I'm still hoping to get the surgery soon, but I would really appreciate an honest go/no-go from a neutral doctor who doesn't stand to gain from my decision. Drs. Corwin and Trattler, do you think I'm best suited to wait for technology to catch up with my pupil size?

Thanks once more. I cannot believe how helpful this forum is!

As I mentioned, I primarily use a VISX laser. But at this time the VISX laser can only treat patients with pupil size up to 6.5 to 7.0mm tops. Patients with larger night time pupil sizes are at risk for significant night time problems.
Patients with thick corneas and 8.0mm pupils can consider LASIK with an 8.0mm optical zone treatment - which the autonomous laser can use. You can contact any of the doctors affiliated with Emory, as they have this laser. As well, Dr. Corwin may be in your area, and he would be familiar with all of the lasers and he uses the autonomous laser.

Best of luck

Bill Trattler, MD
Miami, FL

I'll do the calculations for your prescription and an 8 mm optical zone and get back to you in a day or two. Just off the top of my head, I think your pachymetry will be too thin because as Dr. Trattler says, to use such a large optical zone "eats up" a lot of tissue. With your prescription and corneal thickness, you'd be a fine candidate if you had 6 mm pupils but with 8 mm pupils you may be a no go.

Steven Corwin, MD
EmoryVision
Atlanta, GA

Using an 8 mm optical zone, the laser would use up about 160 microns of corneal tissue to correct your prescription. This would leave you with nothing left if you needed an enhancement, hence an enhancement would not be an option for you even if you were undercorrected after your initial procedure. Are you positive you have an 8 mm pupil? For instance, witha 6 mm optical zone you'd only use 80 microns giving you plenty of reserve for an enhancement. You might want to get that rechecked.

Steven Corwin, MD
EmoryVision
Atlanta, GA

Thanks a lot for running the numbers!

>Using an 8 mm optical zone, the laser would use
>up about 160 microns of corneal tissue to
>correct your prescription. This would leave
>you with nothing left if you needed an
>enhancement

Actually, no doctor ever told me what the minimum remaining corneal thickness is. I assume from your calculations it is ~400um.

>Are you positive you have an 8 mm pupil?

I had three doctors check it. All came up with 7.9-8.1. Sigh.

Assuming that I decide not to do lasik, is there a particular technology or laser I should be waiting for at this point. Should I be looking at another technique like LTK?

Thanks again for all of your help. I'm so glad to have a discussion with an unbiased party. :)

No, LTK is for farsightedness. Only other option is phakic intraocular lens at this time. However, we are doing an FDA trial on this now and you are not nearsighted enough to meet the criteria.

>Using an 8 mm optical zone, the
>laser would use up about 160
>microns of corneal tissue to correct
>your prescription. This would leave
>you with nothing left if you
>needed an enhancement, hence an enhancement
>would not be an option for
>you even if you were undercorrected
>after your initial procedure

Isn't the amount of cornea used determined by the machine used? I thought that some Lasik machines use less cornea then others?

Tom

I was reading what you where telling Peter about his pupil size and how bad his eyse where. Mine are -8.00 and -8.50 with a pupils size of 7.5 and the other slighly bigger. Am I a condidate for Lasik and if so, what type of Laser and how do I find out who has that type of Laser in my area? I went for a consultation and they use the Nidek EC-5000 and they told me that the FDA is in the process of approving an upgrade for this machine that would accomidate my situation. Do you know anything more about this??
Thanks for all the info, it is greatly appreciated.