Dear Dr. Trattler,
What is the pupil size range that would be suitable for lasik? My pupil size is 7.5, is that a safe number? Also, would the Nidek EC 5000 be the appropriate laser for me? Thank you for your help and time.
Amy

1. How near-sighted are you?
2. How much astigmatism do you have?
3. Who checked your pupil size? Has is been rechecked?
4. Why the Nidek laser? It is my understanding that the Nidek only has a 5.5 or 6.0mm optical zone. Please ask your surgeon - but this optical zone may be too small.

Please let me know the answers, so I can comment further.

Best regards

Bill Trattler, MD
Miami, FL

I have a 7mm pupil and my surgeon used a Nidek 5000 laser. I have some night-time ghosting, starbursts and glare issues. Not enough to be debilitating or anything but it is bothersome and I would be *much* happier without them.

Question your surgeon closely about your pupil size measurement (it could be bigger than 7.5mm) and get info on any other patients who had similiar pupil size and perscription also treated with the Nidek 5000.

Night-time vision problems can be debilitating so get all the info you can first.

-Jacque

Amy:
The Nidek EC-5000 has received pre-market approval from the FDA for a 6.5 mm CAZ + 1 mm transition zone. See:
http://www.nidek.com/optzone2.html

Dr. Trattler is asking the right questions. Unless you have a very mild prescription, I would consider the Nidek inadequate for 7.5 mm pupils. You would be getting almost no correction at the outer edge of your pupils.

All the other major lasers provide larger zones:
B&L Technolas 217
Up to 7.0 mm CAZ + 3 mm transition zone
Visx S3
Up to 6.5 mm + 1.7 mm blend zone
Autonomous LADARVision 2000
8.0 mm + 1 mm blend zone

I'm not a doctor.

Let me correct one item in that last post.
The Autonomous LADARVision 2000 has a 6 mm optical zone with a blend zone up to 9 mm (6 + 3). The zone is smaller for eyes with astigmatism. See:
http://www.ladarvision.com/pros/ladarvision/compare_lasers.asp

I've seen the 8+1 number on a number of bulletin board posts but can't find any solid confirmation for it. I tend to believe what the LADARVision website says.

My pupils are 7mm. I had moderate myopia with a hint of astigmatism.
The Visx Star S3 was used with a 6.5mm treatment and a blend zone out to 8.2mm.
I am now 4 months post lasik and experience significant halos and starbursts from headlights and street lamps at night. It's very depressing... so do your homework. Good luck!

First of all, I want to thank everyone for responding to my letter. Just wanted to let you know, that I greatly appreciate your help and time. Now, for my left eye, it's 4.25 & for the right, it's 4.50. If Nidek 5000 isn't right for me. Then which equipment should be used to perform on me? Again thank you.

Amy,

I think you are getting a lot of good advice from doctors and patients alike. Sometimes it can make things even more confusing.

I think it is important for you to realize that all lasers are not created equal, and in general, the larger the treatment zone, the better. This has to be weighed against how deep the laser treats (larger zones go deeper). Finally, all patients have to accept some responsibility for the decisions they make, and currently, NO laser can guarantee the abscence of halos and starbursts post-operatively; although some studies have shown that for good candidates, night vision is better after surgery than before. I am a user of the Visx S3 primarily, and would feel comfortable with your numbers.

Dr. Furlong

>First of all, I want to thank
>everyone for responding to my letter.
>Just wanted to let you know,
>that I greatly appreciate your help
>and time. Now, for my left
>eye, it's 4.25 & for the
>right, it's 4.50. If Nidek 5000
>isn't right for me. Then which
>equipment should be used to perform
>on me? Again thank you.

Hi to all,

I have read the previous link and post by George regarding the Nidek EC5000. It stated that this laser is approved for a optical zone of 6.5mm and transition zone of 7.5mm. Please explain what does this mean? Is this laser suitable for patients with a pupil size greater that 6.5mm? Thanks for your time.

The Optical Zone is also sometimes called the Central Ablation Zone (CAZ). This is the area which will receive 100% correction by the LASIK laser.

Beyond that, some lasers provide a "blend zone" or "transition zone." This is an extended zone that provides tapered correction from 100% to 0%. The advantage of the transition zone is that you get at least some correction beyond the CAZ and it does not require ablating as much tissue as a larger CAZ.
All the major lasers (B&L, Visx, Autonomous, and Nidek*) now allow for transition zones. They help reduce the level and incidence of nighttime vision problems and they allow for treating larger pupils.

*The Nidek has FDA pre-market approval for their transition zone.

While we're on this topic -- a topic that I follow closely -- let me give a rule of thumb for determining if a treatment size is adequate for you. I'm not a doctor but I know some doctors (whom I respect) use guidelines that are roughly equivalent.

For moderate myopia, you want at least 50% correction over the entire pupil. In other words, if your prescription is in the -4.0 to -5.0 range, you can figure that half of the transition zone is good, usable area. For example, a laser that does 6+3 mm would be good for pupils up to 7.5 (6+1.5) mm.

If your presription is weaker, you can get away with slightly larger pupils; if your prescription is stronger, you must have slightly smaller pupils.

But it gets more complicated than this. Depending on your level of astigmatism and level of prescription, some lasers reduce the treatment area size. The Visx and LADARVision, in some instances, provide a smaller, oval-shaped treatment area. So, just knowing the laser's capabilities is not enough; you need to get the actual size that will be applied to your eyes. Your doctor should be able to provide you with this information. You need to know the treatment zone that will be used (including CAZ, TZ and any shrinkage along an axis) so that you can know if the treatment zone is truly adequate for the size of your pupils.

Do your homework. If the rule of thumb says your treatment zone is adequate, then you look at other factors (tear quality, corneal thickness, eye health, doctor's background, etc.). If the rule of thumb says your treatment zone would be inadequate, run!

Thanks George for responding with the useful infomation you provided.

George-
I am not a doctor either, but the doctor I work for was mortified by your disregard for medical science and ineptitude at discussing treatment sizes. I would reserve your opinions for the lay person and stop professing to have expertise in an area where you do not have a license.

I'm mortified with your post. If you have the time to post, then you have the time to ask your "doctor-employer" to put forth a response that is more cogent than George's.

In the absence of that, keep your judgemental mouth shut. George is offering up info that the participating doctors here won't or don't "have time" to do.

If you are not part of the solution, you are part of the problem.

Frank, Sussanah, George (I hope spellings are correct).

The true answer is that there have yet to be good studies that can tell us about the effects of the transitions zones. We know that they help, but we do not know how effective they are for an individual patient.

So everyone can put out there thoughts, and others can disagree, but no one can prove who is correct.

For example - what is the risk of night time problems for a theoretical patient with the theoretical refraction with different pupil sizes and different lasers

-1.00 -2.50 X 90
Pupil size = 7.0, 7.5, or 8.0
lasers:
VISX, autonomous, Nidek, B&L

The answer is - we can only guess - since no study has shown the exact risk of night time vision problems for a specific patient.

What does this boil down to. This means that many patients with large pupils are at some level of risk of night time vision problems depending on their refractive error and the laser that is being used. So for people with large pupils who can not afford to have night time vision problems (airplane pilot, radiologist, taxicab driver, etc) - perhaps one should patiently wait for further studies.

I hope this helps

Bill Trattler, MD
Miami, FL

Susannah:
I welcome your doctor/employer to post his guidelines or opinions regarding LASIK treatment size versus pupil size.

You could say that there have not been enough studies in this area and I would agree. But I would not agree that this provides a medically scientific basis to ignore the relationship.

Currently, the FDA approves LASIK lasers for a range of prescriptions with no regard to pupil size. I consider this a MAJOR flaw in the approval process. This process emerged in an era when the pupil size was believed to be not as critical. But the evidence to suggest otherwise has been building. It is no surprise that all of the major LASIK laser manufacturers now provide their systems with blend zones to provide a larger treatment area. Even without a major formal study, the writing has been on the wall regarding the necessity of increasing the treatment size for larger pupils. All of the major laser manufacturers have reacted. Unfortunately, not all doctors have reacted as well. They are still free to use their older, smaller lasers on patients with large pupils if they consider it good "medical science." This is the reason for the rule of thumb. www.surgicaleyes.org has too many of these cases. Maybe the rule of thumb will help others from becoming one.

By the way, I'm wondering what, specifically, your doctor/employer objects to in my post. What is the maximum treatment size of his laser? I hope he is not a doctor that patients should be running from.

Furthermore, since when do you need a medical degree to discuss patient safety? If he believes this, he has been in an ivory tower too long.

If he wants to refine the rule of thumb or expound upon it, I would sincerely welcome it. If he truly wants medical science to promote patient safety, I would venture to guess that he would promote some sort of approved ranges for pupil sizes for the FDA approval of lasers. Surely, he must agree that there is some limit to the size of a pupil that can be treated with a given laser. Why does the FDA provide prescription limits without providing pupil size limits? In my opinion, they should provide both. A sizable list of LASIK casualties over at www.surgicaleyes.org could have been spared if such a requirement existed.

I recently had LASIK to treat -7.0, -6.5 nearsightedness. My pupils measured 8mm. The doctor used a NIDEK EC5000. I now have serious glare under interior lighting conditions and pretty terrible starbursts at night. Its getting better but I'm still completely distressed.

As I understand, the NIDEK is able to treat high nearsightedness without going as deep as most other lasers. This theoretically would allow the doctor to treat the entire ablation zone (up to 6.5mm)for a full -7.0/6.5 and also provide a transition zone to 8mm or even more. Some of the other lasers would not be able to do that - depending on the corneal thickness (inconjunction with the thickness of the flap).

Nevertheless, I deeply reget having LASIK and would suggest, given all that I have read - dispite clinical research to definitively prove what tons of anectotal evidence suggests - that anyone with greater than 6.5mm pupils should just wait until the technology provides for wider ablation zones.

As Dr. Furlong pointed out, there is a tradeoff between ablation depth and treatment diameter; it is as simple as that. There is no secret or special process that allows one laser type to achieve a shallower ablation without a smaller treatment zone. Regardless of which laser is used, there is a certain resultant corneal curvature which must be obtained to obtain the necessary refraction for your best vision. The only way to achieve the necessary curvature over a wider diameter is to go deeper.

The NIDEK does not go as deep because, as was pointed out, it has the smallest treatment zone of the four major LASIK lasers. Don't get me wrong. When it comes to ablation, shallower is better. But, if you have large pupils which require a large treatment zone, you may not be a good candidate for a shallow ablation.

I'm sorry to hear that you have the glare and starburst problems. You did say that you had the LASIK recently so I believe that you can expect improvement. I picked up nighttime halos from LASIK and I can honestly say that, despite my skepticism, my nighttime vision did improve between six and eighteen months.

My pupil size is 7.28mm in one and 7.78 in the other eye. My no is -2.5 D sphere with - 0.25 cylinder. Corneal thickness is 596 microns. Is my pupil size a relative contraindication to Lasik (wavefront)? Should I have Lasik(custom)?

Fahad,

If the measurement you are providing is your pupil naturally dilated in a low (but visible) light environment, then your pupil size may (emphasis on "may") be a contraindication.

For details on this complicated issue, visit http://www.usaeyes.org/faq/subjects/lasik_pupil_size.htm

Glenn Hagele
http://www.USAEyes.org

I am not a doctor.