Considering LASIK - Another Question

[mkeyes]

Do the new Lasers (e.g. Allegretto Wave by Wavelight) accomodate for larger pupil sizes (e.g. 7 or more)?

[mkeyes]

Also, what measurements should I ask the doctor for to ensure i am a good candidate?

[buddyelf]

Even if the laser supports a larger zone, there is no guarantee that the doctor will give you an optical zone that is big enough for your eye.

A bigger optical zone means more corneal tissue removed, so depending on your prescription, it may not even be possible to get an average sized zone. There has been some suggestion that a deeper treatment removes more nerve endings which results in worse dry eye problems. A deeper treatment also means less corneal strength and residual thickness for a re-treatment, which is worsened by any complications. These factors discourage the design of treatments with large optical zones.

The newer lasers tend to use larger blend zones, but this only means smaller, more gradual halos, NOT no halos. Those same lasers support larger optical zones, but usually the maximum is 8mm. Also the halo size will be proportional to the magnitude of your prescription. Some people have pupils that reach 9mm in darkness so there are definitely people out there who simply cannot be treated without any complications.

You will also may be unpleasantly surprised to find out that the Pupilometer used to measure your pupil size is not especially accurate. They don't usually get your absolute maximum dilation size.

Let me give you an example of a treatment many doctors will consider an excellent outcome:

Your doctors measured 7mm pupils in a dim room. You get treated with an optical zone of 6.5mm. In a dim room you sometimes see very tiny streaks or haze that some out of brighter colored objects, but it is almost unnoticeable. When driving at night on a dark road you see mild irregularly shaped halos out of all light sources.

Your pupil size can be affected by fatigue, physical activity, and a number of other normal factors. If you don't believe me, try taking a very deep breath while looking in the mirror. (Works better in a dim room.)

What you should be even more worried about, is what will happen if you try to take antidepressants or other drugs that open your pupils after lasik. Most likely you will have massive debilitating halos in all lighting conditions, as it will force your pupils to be much larger to whatever pupil value they measured before treatment.

You need to realize that doctors will design a treatment that they know will give you some halo problems. The only question is how bad of a halo outcome would stop them from treating you or cause them to admit that you aren't an ideal candidate. Many doctors will be happy to let you take pupil constricting drugs for the rest of your life and call it fixed.

Asuming you do end up halo problems, as you age, your pupils become less able to open widely, so your halo problems will get less severe with age.
And as a bonus, you can easily tell if you are suffering from a head injury, as it causes pupil dilation that may give you larger than normal halos.

If you can not accept having halos, don't get Lasik. Sometimes the difference between somebody who is happy with their Lasik, and one who is not, is simply that one is coping with their halo problems better.

FYI, asking questions on this forum is probably a waste of time. I asked several questions here and have never gotten a complete or accurate answer.

[ste71m]

Hi buddyelf
Since you seem so experienced i would like to ask you an opinion
I'm seriously considering having prk or epilasik
Pupils in low light: 5 mm
Left Eye
-5.25 myopia -1.25 astigmatism
Mean pupil=2.734 mm

Right Eye
-5.50 myopia -0.25 astigmatism
Mean pupil=2.925 mm

My doctor propsed an ablation zone of 6.5 or 7 mm
What's your opinion about chances of halos and starbusts?
Thanks

[PRKorIntacs]

Your 5mm pupils are smaller than average. You are at less risk for halos, starbursts, and poor night vision. My pupils could be 8mm, this is one reason im considering Intacs over PRK among many others. See my thread on this.