I had surgery scheduled last Friday and met with the Surgeon before the procedure. I had been warned about my pupil size (chart said 7mm) and queried the Surgeon. He dimmed the lights and re-checked me and said I was closer to 8mm-8.5mm. He then convinced me that I should not be done on the VisX StarS2 and should be done on the other machine he uses, the B & L Technolas 217A (more expensive). He feels that since I am an engineer (more likely to be finicky)and I have large pupils, he recommends the Technolas because of it's larger ablation area and smoother transition area. The VisX apparently treats a 6.5mm dia area. I also have the option of another surgeon with the Nidek EC-5000. My prescription is only -1.5D in both eyes. Is the Nidek better for me? Is the Technolas truly better? Very frustrating.
Thanks in advance for your help.
S. Hood

I wish I had the perfect answer for you. I can tell you that with the VISX (which is what I use), we generally do not see any pupil-related LASIK problems for patients with low levels of myopia. For a patient with 1.5 diopters of myopia, less than 24 microns of corneal tissue is removed by the laser (most people have a corneal thickness of 500 to 580 microns).
There are some lasers other than the VISX that can treat "wider" - and the question that we all have is whether this provides a clinical advantage. Barrie Soloway (from Manhattan) discussed his paper using the Alcon-Autonomous laser where he expanded the treatment zones based on the patients pupil size - and showed that the patients were all very happy. However, he did not comapre the treatment to another laser, so we can not know whether the other lasers (including the VISX) would have had similar good results. Both the Technolas and Nidek can provide wider ablations - although they may be using a "transition" zone - which may or may not have a big effect.
I hope you find this answer helpful - although it may be more confusing because the answer is that most people with large pupils and very low myopia will do well with all lasers - but - if you are very concerned - then using a laser that can treat a wider ablation may help reduce your concerns/fears.

Best of luck

Bill Trattler,MD
Miami, FL

I have 8 mm pupils and my vision is ruined not only at night, but indoors as well. I was a pretty low myope.

Don't buy it!

Hi Daniel - here's a copy of an item I sent to a patient earlier in the year about large pupils - this may be of help to others:

1) To answer your question about larger pupils (greater than 6 mm diameter in dim light) and LASIK surgery outcomes, it helps to know a little physiology:

Light passes through the cornea to the pupil, the hole in the middle of the iris, or colored part of your eye. Depending on how bright the incoming light is, the pupil grows wider or narrower, much like the adjustable aperture of a camera. Light then passes through the lens, which lies directly behind the iris and changes shape as needed--curving or flattening--to help focus the image onto the retina.

Some patients may experience mild glare or halos after being treated with LASIK, at first - usually at night or under fluorescent lights. This occurs because the pupil widens in dim light, allowing incoming light to pass through both the corrected and uncorrected sections of the cornea, creating glare or other aberrations. The problems usually diminish within six weeks to six months.

An equally critical factor, however, is the amount of correction you need, measured in negative (-) diopters for nearsightedness and positive (+) diopters for farsightedness. The greater your correction, the more abrupt the transition zone between the sculpted and unsculpted portion of the cornea, and the greater the risk of glare and halos. Most of the lasers currently used for LASIK can sculpt an area no wider than 6.5 mm, or a quarter of an inch. So, as you might expect, patients whose pupils grow wider than the average of about 6 mm in the dark may be prone to glare or other aberrations.

This is why Douglas G. Miller, MD (a fellowship-trained Cornea Specialist) chooses to use the VISX Star S2 excimer laser - because the technology advantage with VISX is greater than with any other laser.

How can the excimer laser affect your satisfaction with LASIK?

- The VISX laser has a 40% larger optical zone than the Nidek laser (as used by most of the "discounters"). Larger optical zones improve the quality of night vision. (Ghosting, starburst, glare or halos are more common if the laser utilizes smaller optical zones.)

- The VISX laser achieves smoother corneal surfaces, resulting in more rapid visual recovery and better visual acuity. The VISX laser produces the smoothest surface of any excimer laser system.

- The VISX laser systems have the widest treatment ranges approved by the FDA, for nearsightedness, farsightedness and astigmatism, than any other laser; has greater clinical expertise and best track record in the US.

PLEASE DO REMEMBER: It's the surgeon and not nec the laser that REALLY matters. Find a surgeon, if you can, who has treated a great number of patients with larger pupils. Talk to her/him about her/his own surgical outcomes and ask to speak with some of her/his patients.

Best of luck to you all.

Could you please be so kind as to tell me your preoperative presrciption, and please discuss your level of night time problems before LASIK. As well, could you please tell me whether wearing glasses or contact lenses improves your night time symptoms.

Thank you

Bill Trattler, MD
Miami, FL

Thanks for the responses. I'm confused by Suzette's VisX information, though. It sounds a little like a marketing brochure for VisX and maybe is a little dated? Dr. Trattler's response to my original question said "Both the Technolas and Nidek can provide wider ablations - although they may be using a "transition" zone - which may or may not have a big effect." Suzette's VisX information says: "The VISX laser has a 40% larger optical zone than the Nidek laser" and "The VISX laser systems have the widest treatment ranges approved by the FDA". Which is correct? Which has the widest ablation area, VisX, B&L or Nidek?
Thank you,
S. Hood

It is a Marketing brochure because she's the marketing director for a doctor. It really didn't add much to the discussion IMHO.

There are two issues with lasers as far as treatment zones - one is called the "optical zone" and one is called the "transition zone". Nidek laser have a smaller "optical zone" but then feather out the treatment in what is called a "transition zone". I believe that with the autonomous, the doctor can specify a larger optical zone - but this has the side effect of requiring exponentially more removal of tissue. There is actually a formula - which I will be happy to share. But basically - for a 6 mm optical zone - a laser removes 12 microns per diopter of myopia. For an 8 mm optical zone, the laser on average removes 21 microns per diopters. So you can see that increasing the optical zone causes an increase in the amount of corneal tissue that is removed.
The VISX has a true 6.5 mm optical zone, but does not have a transition zone.

I hope this clears things up a little. For patients with high degrees of myopia and large pupils - there often is not enough corneal thickness to perform a very wide optical zone treatment - but for patients with low levels of myopia - a wider optical zone can be used (this is with the autonomous laser). But - for most patients with low levels of myopia - night time problems are not a significant issue.

I hope this helps

Bill Trattler, MD
Miami, FL

I had LASIK in early July of 2000 with a Technolas laser. After the treatment, I immediately had problems seeing out of my right eye. I went back the next day and the doctor lifted up the flap and irrigated my eye to remove debris. Over the next several months my vision improved from my pre-surgery -8.5 with +2.5 of astigmatism. My vision in my left eye is very good when I am outside in very bright light. My left eye has poor vision. I see halos and my vision is severly diminished at night.

My original doctor and a second opinion doctor say that all I need is an enhancement to correct both my eyes. My right eye is overcorrected and is about +1.5 with a -5 of agstimitism. My left eye is about +.25 -.25.

Since I am having so much trouble at night, the 2nd opinion doctor suggested that when I have the enhancement I ask the surgeon to make the optical zone bigger to fix the night problems. My cornea thickness is approximately 430. What do you think?

There are a number of possibilities for you. My first concern is the residual corneal thickness. You must talk with your surgeon to make sure that the corneal thickness will be sufficient. For hyperopic treatments, the central cornea is generally not lasered - so hopefully thickness will not be an issue. But you should certainly discuss this with your surgeon.
The other possibility is a procedure called LTK. LTK works for patients who are far-sighted. I am not familiar with studies using LTK to treat over-corrected LASIK patients. LTK works by placed 8 laser spots on the peripheral cornea, which induces the central cornea to steepen.

I hope this information is interesting and helpful

Best of luck

Bill Trattler, MD
Miami, FL

I had the surgery performed on the technolas eleven days ago and all went well. I have slight halos but they occur around all bright objects both during the day and at night. I'm told this will fade as the cornea heals. My vision is 20-10 in both eyes. Reading causes slight eye strain but at 40 years old I know reading glasses are in my near future. I highly recommend Lasik.

sa

Dr. Tratter,

My pupils are 8 mm measured by ruler, and at least 8.3 with a Colvard.

My pre-op Rx was -3.75 and -3.50. I had flare around my contacts before LASIK, which looked like an eclipse in movie theatres. I had LASIK on a Visx laser with a 6 mm zone. I am told that the optical zone decreases as the cornea heals.

Glasses do not help with my night vision. I have 10 mm RGP contact lenses now. Instead of the starbursts I have without the lenses, with the contacts I have huge halos. In my best eye, the halos really look like a ball of thousands of tiny rays of extremely bright light. They are blinding, and I cannot drive safely at night either with or without the contacts. It was been 14 months since my surgery, and my night vision has never improved. In fact, it worsened after the first 3-4 months--probably due to the shrink in the optical zone.

I have heard over and over again from doctors that the risk of night vision problems is only for high myopes with large pupils. Not always true!!!

Thank you so much for providing all of that information. If you were my patient, here are the next set of things to consider/try

1. Do the night time symptoms disappear with the pinhole test?
2. On corneal topography, do you have irregular astigmatism or a central island?
3. Have you tried Alphagan drops at Dusk? Please talk with your doctor about these drops, as many LASIK patients with higher levels of myopia and night time problems report an improvement in their symptoms. This is a very common eye drop, with its main efffect being to lower the pressure. However, I have heard many positive reports with this medication.
4. Have you tried low dose pilocarpine (1/4%). I know that 1/2% is the lowest dose that is commercially available, but 1/4% can be made up by a pharmacy, and can cause mild pupil constriction and a significant decrease in night time symptoms, without the side effects of regular pilocarpine. Please of course talk with your doctor about this.
An interesting note - patients who have taken pilocarpine for years get a permanent reduction in their pupil size. So this may be an advantageous side effect for you.
5. Another interesting option - is that some LASIK experts have reported that they can widen the optical zones by performing a astigmatic keratectomy (AK). I do not know whether you have any astigmatism, but if you have some residual astigmatism, this procedure may be an option. I do not remember who the surgeons were who discussed the enlargement of the optical zone at the 1999 American Academy of Ophthalmology, but if you are interested, you can have your surgeon call me, and I will be happy to help him/her contact those doctors.

Well - I hope this is a good start. I am more than happy to provide clarification or comments to any further questions that you might have. I would also love for you to keep me informed as to whether any of these ideas provide help

Best of luck

Bill Trattler, MD
Miami, FL
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