larpe pupils for epi-lasik???

[mokanss]

Hello everyone and thanks to all who share their energy to keep this site going. sorry for poor english in advance.

I've been considering long to have refractive surgey and been searching many sites and medical journals to make up my mind (in fact to wipe away my fears as i really do).

as i mentioned above, i did a pretty deal of research ( i know it is never enough) and at last found a doctor advised to my mother, a prof at a medical school, by her colleagues. this doctor works for a eye hospital chain in Turkey where i live. The chain really scared me cause i dont like the idea of mass eye surgeries. I had my pre-op exams and finally saw the doc to talk about my results. he said that my eyes had two risk factors and he would not suggest refractive surgey to me. he said i had thin corneas and (this is where i've all searched for lost its meaning because of the limited capacity of my medical understanding :) ) there was some sort of assymetry between the topografies of my cornea. he said one had vertical something and the other ????. According to my results, my corneas were about 510microns both. he explanied that there was risk of ectasia, which i know how develops. he said he would not do lasik and if i insisted he might go for epi-lasik which would reduce the chances of ectasia for about 80-90% compared to lasik. i said if he considered me a risky patient then i would not have any surgery, thanked him and left his office.

At first i was really glad as i thought he told me the truth and just did not try to get me on the table. however some time later i started to wonder if he was just being too conservative. As far as i know, any cornea thickness between 500 and 600 mic is considered to be normal. Although my corneas are on the thin side i ve come across my experiences where surgions performed operations. being not satisfied i went to another doc and had all the exams once again. this doc is also an famous doc (if it does any good???) and also has an office in the netherlands. not to my shock he said i was eligible for lasik. since the first doc already ruled out lasik, i had also made up my mind to go with surface ablation ( if i can have any surg) prior to this second doc. i asked him why i was eligble and told him about the first doctors concerns. he said my readings were within the limits. when i asked about corned thickness he made a simple calculation showing that my stroma would be thicker than somewhere more than 300mic with intralase lasik. (my corneas turned in around 10mics thicker at this exam). i declined this option and said i would only have surface ablation. he did not seem willing and made jokes about me beign whether masochist (not with an intention to insult) and i would curse him all the way through first two nights. seing me determined he said ok to epi-lasik if it would make me fell more relaxed. this came right before i asked him about my pupil size. he said they were 8mm!!. they are huge. when asked if this was a problem he said ok once again. i returned to home to do some more searches and read about usaeyes' "Lasik Halo and Starburst; Pupil Size Importance" and other sources.could not reach a final conclusion!! dropped at the second medical centre the other day to learn if these results were from my dilated eyes (drops) and learned they were from dim light. once again research and they were measured with "colvard pupillometer".

do you think having 8mm pupils is a problem for surface ablation particularly for epi-lasik (not custom). think they use Allegretto.

my readings follows.
right -3.00 (-1.00 ax90)
left -4.75 (-0.25 ax30)

according to my orbscan from first doc :
right:
white-to-white(what is this??): 12.0mm
pupil diamater:3.9mm
512um@(-0.8, -0.6)

left:
white-to-white: 12mm
pupil diameter:4.0mm
518@ (-0.4, -0.2)

[LasikExpert]

I believe that the first doctor may be concerned that you have early signs of what is called forme fruste keratoconus.

Keratoconus is a disease of the cornea that causes weakening and can lead to forward bulging of the cornea. Keratoconus normally presents before the fourth decade of life. One of the first signs of keratoconus is a progressive astigmatism in the lower portion of the cornea and an elevation on the back side of the cornea at the same location. Astigmatism alone does not mean keratoconus. Forme fruste keratoconus can be described as keratoconus before it has caused any real symptoms.

The use of rigid gas permeable contact lenses can reduce the effects of keratoconus. Keratoconus tends to run in the family. Has any of your relatives had corneal transplants or been dignosed with keratoconus?

All laser vision correction surgery techniques involve removing corneal tissue and thus weakening the cornea. Many studies have shown that a healthy cornea with at least 250 microns of untouched tissue (more is always better) will almost always remain stable. An unhealthy cornea - especially a keratoconus suspect - may not remain stable after vision correction surgery.

Lasik removes tissue deeper in the cornea and this provides less untouched tissue. If you were to seriously consider laser vision correction surgery, then you probably should only consider a surface ablation technique like PRK, LASEK, or Epi-Lasik.

If the concern is keratoconus, then the first doctor may be a bit on the conservative side, and the second doctor may not have diagnosed the same potential problem. It is not unusual for two reputable doctors to come to different conclusions about something as difficult to diagnose as forme fruste keratoconus.

A Colvard pupilometer measures pupil size in total darkness using an invisible infared light. As a general rule, the actual pupil size in a low, but visible, light environment is about 1.0mm smaller than what is measured with the Colvard. Your naturally dilated pupil size is probably closer to 7.0mm than 8.0mm.

Your refractive error is relatively low, but your astigmatism is significant enough that full correction throughout the size of your fully dilated pupil would provide the highest probability of a good outcome. I do not know the size of the full optical treatment zone of the Allegretto available in Turkey.

You have read our article about Lasik and large pupils so you know that there is possibly an elevated risk, but due to your moderate myopia (nearsighted, shortsighted) vision the risk may not be too elevated if the full optical zone is within 0.5mm to 1.0mm of your natually dilated pupil. This is a judgement call.

[mcgross]

Hello I had Lasik on March 7th. My vision before was -5.75 in the left and -5.25 in the right eye. My pupils also measured 8mm when tested. My main fear was that I would not be able to drive at night after the surgery. But that has not been the case. The next day my vision tested 20/20 and I was able to drive at night 2 days after. There are halos around lights, but it isn't unbearable and is improving.
Hope this helps!

[mokanss]

thanks everyone for their kind replies.

i decided to consult another doctor working at a university and doesn t perform refractive surgery. He will exam me for any chances of keratoconus and besides i will have all other pre-op examinations once again. (no harm i guess). i'm still determined for going on surface ablation if i ever have surgery(most likely for epi-lasik). does surface ablation or lasik differ in any sense when it comes down to treating corneas with large pupils?? i mean, for example, surface abaltions is usually better for thin corneas. can we make a similar classifaction for large pupils or is it just the right laser with correct treatment zone?? i know each surgery depends on the patients eye and every surgery is unique. so i may be asking a wrong question.

[LasikExpert]

The larger the ablation zone, the more tissue needs to be removed for the same correction. To accommodate thin corneas, some doctors will make the ablation zone smaller to remove less tissue. Because a surface ablation technique like PRK, LASEK, or Epi-Lasik disturbs less tissue depth, a full sized ablation zone is more likely appropriate.

[mokanss]

hello once again.

gleen thank you very much for your help and thanks for this site. been googling the web for some time and this is definetely the best.

upon your considerations i scheduled a meeting with a doc who will seek signs of keratoconus if there are any. i will also talk and learn his thoughts on refractive surgery. as far as i know he doesnt perform any.

i would also like to ask for an confirmation. i mentioned of my large pupils earlier (8 mm). if the surgeon goes with 8mm of ablation zone is the following calculation correnct for tissue removal.

3.00 x (8mm x 8mm/3)= 64micron
4.75 x (8mm x 8mm/3)= 101microns

these calculations do not take into account my astigmatism and transition zones i guess. so actual figures will be bigger i think. is it true or am i missing some point.

as a final question, does epi-lasik include a standard amount of tissue removal regardless of diop or ablation zone. for example for lasik calculation flap thickness can be constant at, lets say, 110, 120 or 160 mic. is there any constant that should be added when making calculations for epi-lasik like the thickness of epidelium.

thanks in advance

[LasikExpert]

gleen thank you very much for your help and thanks for this site. been googling the web for some time and this is definetely the best.

Thank you for the kind words. We do try to keep up to date and balanced. That does seem hard to find.

i would also like to ask for an confirmation.

Calculations for the amount of tissue to be removed are more and more complex due to wavefront-guided ablations. The standard Munnerlyn formula is 12 microns for every diopter of correction with a 6.0mm optical ablation zone. A larger ablation zone means more tissue per diopter.

Wavefront-guided ablations start with Munnerlyn, and then add changes for higher order aberrations. This means that the ablation can be much deeper in one area than another. The only way to really know is to look at the ablation pattern generated by the laser's computer based upon your own unique wavefront.

Fortunately, all these calculations can be made by your doctor before you make a decision about surgery.

as a final question

All laser assisted vision correction surgery techniques - Lasik, All-Laser Lasik, SBK, PRK, LASEK, and Epi-Lasik - will calculate the same ablation for the same patient. Some doctors will make adjustments based upon prior experiences, but the computer does pretty much the same thing no matter what the flap or lack of flap.

All laser assisted vision correction surgery techniques must abide by the same physics, so a larger optical ablation zone for one will have the same changes for an equally larger optical ablation zone with another technique.

[mokanss]

hi again,

a quick update after my third consultation.

The doctor i went to see checked my eyes with something called pentacam. he said this instrument was much superior compared to orbscan which was the device used by the first two surgeons. I've never heard of this machine and didn't know what to think becuase each doctor promotes the machine he uses as the best. Anyway the guy does not perform refractive surgery (thus he has no interest) so he may be correct! Thats just a thought of course. He also did a slit lamp examination for keratoconus. He said my corneas were perfectly healthy and in his opinion i was a perfect candidate for epi-lasik. Then just to be sure he advised me to take another test called "Ocular Response Analyzer". He told me that this was the new trend in refractive surgery and every one should take this exam to minimize chances of developing post-op ectasia. he doesnt have the ocular analyzer so i am scheduled for another examination with an other doctor. if i pass!! that test too, i think i will have my surgery. will keep u updated

best,

[LasikExpert]

The Pentacam is a relatively new device with technology providing improved diagnosis of corneal irregularities. It was very wise for your doctor to order this test. The Ocular Response Analyzer (ORA) uses a detailed method of analysis to determine the strength of the cornea. All of these tests will help determine if you have corneal disease.

A corneal specialist affiliated with a university who does not perform refractive surgery would undoubtly provide an unbiased evaluation.

[mokanss]

Hello everyone.

I had the ocular response analyzer test and my cornea's turned out to be strong enough. I don't knoe the scale for interpreting the results but i was told that all my measurements avaraged around "10". A level below "9" was not approporiate for any kind of refractive surgery so i am good to go. However the last and and probably the most experienced surgeon i ve last consulted told me to have LASEK. When i told him of my choice of epi-LASIK he assured me i would do fine with LASEK.

Now i am confused once again. From what i've read epi-LASIK heals slightyly faster compared to LASEK and is less painful. However this is the newest procedure so this may be only marketing talk. The newest technology has to be sold!!!. Maybe he hasn't done enough epi-LASIK surgeries? What would you advise me? epi-LASIK or LASEK?

[LasikExpert]

There was an open debate at a recent ophthalmology convention and the conclusion was that LASEK and Epi-Lasik are really not better (or worse) than PRK. You would likely have the same long-term result with any of them. Go with what your surgeon recommends.

[mokanss]

Hi,

I am still very confused about whether to have refractive surgery or not. So far I visited 3 doctors one of which advised me not to have surgery while the two others said i was ok to go. Finally i visited the doc who said no for second time and he once again did an orbscan. I am posting my scans here. What the doctor actually said is that my left eye (in fact cornea) is pretty healthy as there is nothing wrong with it. However its my right eye (cornea) that causes the problem. Doc said that the axis of my cornea (the bottom left map on orbscan- axis is the red lines) had become rather horizantol compared to my left eye (left eye is vertical). The doc said that this situation of having assymetric axis was a warning for post-op ectasia and urged me not to have any surgery. If this is so obvious, why the two other docs said i was ok? any opinions on my orbscan.

right eye's orbscan:



left eye's orbscan:

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[mokanss]

Hi everyone,

I decided to shelf my posibble laser surgery for at least two years. I will go with the decision of the doctor who said i should not have it. I will wait for two years and see if my cornea's shape changes in a negative way. I'm keeping all my readings and will compare them with future tests. Wish everyone best and hope all gets to see well!!

[LasikExpert]

You decision is wise.

I am not a doctor nor am I trained in orbscan analysis, but I've seen quite a few over the years and the inconsistency between the posterior float and the anterior float of the same eye is a cause for concern. The "hot spots" of the anterior float of both eyes is cause for concern. This is an indication of possible corneal disease such as keratoconus, which would likely be exacerbated by any laser vision correction technique.

It would be wise to have the orbscans taken with the same parameters each year for a couple of years and watch for progression.

If you wear rigid gas permeable (RGP) contact lenses, they can "mask" keratoconus effects, making the disease less apparent in orbscans.