Custom Wavefront, HOA and "tired eyes"

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Custom Wavefront, HOA and "tired eyes"

Postby smilingsmeagol » Wed Mar 14, 2007 9:32 am

I have a question about Custom WaveFront and higher order aberrations. I went to a doctor in late January to schedule a Custom Wavefront assisted PRK procedure, and had my eyes screened using Alcon wavefront machine. I went back to the same doctor a month later and he mentioned that the higher order aberrations in my eyes were too bad to have Custom Wavefront, but I could have the unassited laser procedure done. During this second visit, I waited in the office for 9 hours, and was reading magazines for a good part of it. My questions are:

1. I am really hoping to get the Custom Wavefront since I am told the results will be much better, I rescheduled for the procedure with the same doctor this Friday 3/16/07. Does it make sense that my scores can be affected by having "tired eyes" and what can I do to make sure my eyes are not too tired? I am using the artificial tears prior to the procedure, and will make sure I dont read for any period of time before the procedure.

2. If there is nothing I can do about the test results, will not having Custom Wavefront provide decent results? I am concerned since I have large pupils, and am concerned about the Halo effect and appreciate how custom wavefront can help minimize this. I don't mind jumping through hoops to make sure I can get the best possible results.

Thanks!


I saved the scores below.

January 26, 2007
Left Eye

Higher Order Aberrations: 0.84 Microns

Wavefront
Sphere -0.68 Diopters
Cylinder -0.96 Diopters
Axis 35 Degrees
Match 75%
Diameter 6.5mm

Phoropter
Sphere -1 Diopter
Cylinder -0.5 Diopters
Axis 40 Degrees

Right Eye

Higher Order Aberrations: 0.92 Microns

Wavefront
Sphere -1.3 Diopters
Cylinder -0.43 Diopters
Axis 170 Degrees
Match 76%
Diameter 6.5mm

Phoropter
Sphere -1.5 Diopter
Cylinder -0.5 Diopters
Axis 3 Degrees
*************************

March 2, 2007
Left Eye

Higher Order Aberrations: 1.09 Microns

Wavefront
Sphere -0.76 Diopters
Cylinder -1.36 Diopters
Axis 25 Degrees
Match 72%
Diameter 6.5mm

Phoropter
Sphere -1.25 Diopter
Cylinder -0.75 Diopters
Axis 45 Degrees

Right Eye

Higher Order Aberrations: 0.71 Microns

Wavefront
Sphere -1.28 Diopters
Cylinder -0.5 Diopters
Axis 17 Degrees
Match 80%
Diameter 6.5mm

Phoropter
Sphere -1.5 Diopter
Cylinder -0.5 Diopters
Axis 3 Degrees
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Re: Custom Wavefront, HOA and "tired eyes"

Postby LasikExpert » Thu Mar 15, 2007 2:13 am

smilingsmeagol wrote:1. I am really hoping to get the Custom Wavefront since I am told the results will be much better...


The results of custom wavefront PRK are better for those patients who are appropriate candidates. If you are not an appropriate candidate wavefront-guided surgery could cause significant problems.

smilingsmeagol wrote:Does it make sense that my scores can be affected by having "tired eyes" and what can I do to make sure my eyes are not too tired?


If you are presbyopic (less able to focus on near objects) then nine hours (?!) of reading could affect the tests, however the doctor may have performed cycloplegic tests that neutralize the effect all that focusing would have.

If you are well under age 40 and not presbyopic, reading is not terribly likely to have have made much difference, but express these concerns to your doctor before making a decision.

smilingsmeagol wrote:I am using the artificial tears prior to the procedure, and will make sure I dont read for any period of time before the procedure.


Do you normally use artifical tears? Had you been using artifical tears at the time of your examination? Are the artifical tears you use preservative-free? (They would come in individual single-use vials). Were the artifical tears prescribed by the doctor? Do you have a current dry eye problem? Hydration is an important issue in refractive surgery. All of this information should be provided to your doctor.

smilingsmeagol wrote:2. If there is nothing I can do about the test results, will not having Custom Wavefront provide decent results? I am concerned since I have large pupils, and am concerned about the Halo effect and appreciate how custom wavefront can help minimize this. I don't mind jumping through hoops to make sure I can get the best possible results.


Large pupils may be the reason wavefront-guided ablation is not being recommended. Your level of Higher Order Aberrations (HOA) may be an issue. The artificial hydration of your eyes may be an issue. If you are nearing age 40, Sudden Presbyopia may be an issue.

This is elective surgery. Nobody is required to have PRK and you are not requied to have it on the date currently scheduled. You have several relevant and important questions that may have excellent answers, but until you know these answers you are not making an informed decision.

Based only on the information you are providing, I personally think you need to stop jumping through hoops, get the opinion of another surgeon or two, and take your time with this decision. You will live with the results for the rest of your life. There is no reason to rush now.
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Postby smilingsmeagol » Thu Mar 15, 2007 7:19 am

Thank you for taking the time to give me your feedback, I really appreciate your expertise. I have answers to your questions below:

[quote]The results of custom wavefront PRK are better for those patients who are appropriate candidates. If you are not an appropriate candidate wavefront-guided surgery could cause significant problems.[/quote]

>>When I got the second wavefront test done, it was right before I was scheduled to get the PRK procedure. He said that he did not want to do the wavefront procedure due to the results, and so I told him that I would like to come back in 2 weeks time to make sure that environmental factors (reading, tired eyes, etc) were not detrimentally affecting my wavefront test scores. My main question is whether the higher order aberrations numbers vary on a periodic basis? Do you agree with his assesment based on the values of my HOA's?

[quote]If you are presbyopic (less able to focus on near objects) then nine hours (?!) of reading could affect the tests, however the doctor may have performed cycloplegic tests that neutralize the effect all that focusing would have.

If you are well under age 40 and not presbyopic, reading is not terribly likely to have have made much difference, but express these concerns to your doctor before making a decision. [/quote]

>> I am 33, and do not have problems focusing on near objects. I've been to 2 Doctors already, and none of them have mentioned that I am presbyopic.


[quote]Do you normally use artifical tears? Had you been using artifical tears at the time of your examination? Are the artifical tears you use preservative-free? (They would come in individual single-use vials). Were the artifical tears prescribed by the doctor? Do you have a current dry eye problem? Hydration is an important issue in refractive surgery. All of this information should be provided to your doctor. [/quote]

>> The artificial tears are Allergan Refresh Tears Lubricant eye drops (Carbomethylcellulose sodium 0.5%). I normally don't use it, however the doctor recommends to all of his patients to use it liberally for a few days before the procedure. I don't have a dry eye problem.

[quote]Large pupils may be the reason wavefront-guided ablation is not being recommended. Your level of Higher Order Aberrations (HOA) may be an issue. The artificial hydration of your eyes may be an issue. If you are nearing age 40, Sudden Presbyopia may be an issue.

This is elective surgery. Nobody is required to have PRK and you are not requied to have it on the date currently scheduled. You have several relevant and important questions that may have excellent answers, but until you know these answers you are not making an informed decision.

Based only on the information you are providing, I personally think you need to stop jumping through hoops, get the opinion of another surgeon or two, and take your time with this decision. You will live with the results for the rest of your life. There is no reason to rush now.[/quote]

>>I appreciate the word of caution and am proceeding with a care. This is the second doctor I have seen, and he has done many procedures (40,000+), comes with a good reputation, and has treated 3 of my closest friends. They have all mentioned that he treated them with respect and candor - which is what I am experiencing with him now.
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Postby LasikExpert » Thu Mar 15, 2007 3:39 pm

smilingsmeagol wrote:My main question is whether the higher order aberrations numbers vary on a periodic basis?


Higher Order Aberrations (HOA) vary from moment to moment. When the wavefront aberrometer scans your eyes, it actually takes five scans in an instant. Each of these scans will have different results because the optics of the eye are very dynamic. The system ignores the highest and lowest scan and averages the three middle scans. That is the reported result.

Take ten scans and each will have a slightly different result. There are many variables that contribute to HOA fluctuations. Being young would indicate that hours of reading would not have caused a long-term change in your vision, however another scan without prior reading would affirm that assumption.

smilingsmeagol wrote:Do you agree with his assesment based on the values of my HOA's?


I suspect that the rejection was not due just to the HOAs. I suspect that there are other factors, such as corneal thickness, pupil size, etc., that when combined indicate that wavefront-guided is not the most appropriate.

smilingsmeagol wrote:I am 33, and do not have problems focusing on near objects. I've been to 2 Doctors already, and none of them have mentioned that I am presbyopic.


At 33 you probably are not presbyopic. Presbyopia usually does not become problematic until after about age 40.


smilingsmeagol wrote:The artificial tears are Allergan Refresh Tears Lubricant eye drops (Carbomethylcellulose sodium 0.5%). I normally don't use it, however the doctor recommends to all of his patients to use it liberally for a few days before the procedure. I don't have a dry eye problem.


If this is a part of the doctor's normal routine, then the doctor's nomograms for treatment would undoubtedly be adjusted for this level of hydration. It is something out of the ordinary routine that would be of concern. Following your doctor’s instructions would not be out of the ordinary. Well, it shouldn’t be.

smilingsmeagol wrote:I appreciate the word of caution and am proceeding with a care. This is the second doctor I have seen, and he has done many procedures (40,000+), comes with a good reputation, and has treated 3 of my closest friends. They have all mentioned that he treated them with respect and candor - which is what I am experiencing with him now.


Then it seems that you need to discuss these issues with the doctor you trust and respect to learn the reasoning behind the recommendations. Then you can make an informed decision if in light of the additional information you believe it is best to proceed.

Please keep us informed.
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Postby smilingsmeagol » Thu Mar 15, 2007 10:59 pm

So my only question at this point is whether getting the PRK + laser treatment (LADAR ?) is worthwhile if I cannot get the customwavefront assist. The dr did mention that I was a perfectly good candidate for that, and that there is decent success rate for that. My expectation is that I will have a solid chance at getting 20/20 vision (since I am young with a very slight prescription), but that since I have HOA's, I may not have as clear vision with this treatment as a person getting customwavefront assisted treatment.

Can you comment on this?
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Postby LasikExpert » Fri Mar 16, 2007 12:40 am

As a general rule, all cornea-based laser refractive surgery techniques induce higher order aberrations (HOA). As a general rule wavefront-guided ablation induces few HOA than conventional ablation. There exceptions to every rule and some patients with both techniques can have a reduction of HOA, but not predictably.

You have lived with these HOA all of your life and your brain has learned how to compensate for them, perhaps even taking advantage of them. Based upon the information you have provided, your HOAs appear to be elevated from the norm. While you may now have good vision (with corrective lenses), the concern will be is if you are at the threshold of poor vision, if surgery will increase your HOAs, and if that change will cause you to have poor quality vision. This would be the kind of poor quality of vision that would not be able to be corrected with glasses.

You need to discuss with your surgeon the probability of this problem for your unique circumstances.
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Postby smilingsmeagol » Sat Mar 17, 2007 10:23 am

I just came back from the dr's office. I took the wavefront exam again and had the same test scores. The dr told me that my HOA scores were still high (1.08 microns and 0.8 microns). He told me that these numbers are 5 to ten times the norm. He said that my HOA scores combined with my large pupil diameter, put me in *a* risk for having permenant/uncorrectable night time halos and starbursts even if I went ahead with the unassisted refractive surgery (LADAR). He explained the worst case scenario being that I would not be able to drive at night. He would not quantify the risk, nor elaborate if it was a high risk that I would have these effects. He decided to cancel the procedure because he fealt that I did not want any risk (which was never my expectation) and suggested I wait a few years until the technology improved.

My main issue is that he was willing to offer me unassisted refractive surgery just 2 weeks ago, so the overall risk must not have been that bad. I will proceed to get a second opinion on my case and give an update.
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Postby LasikExpert » Sat Mar 17, 2007 4:50 pm

smilingsmeagol wrote:My main issue is that he was willing to offer me unassisted refractive surgery just 2 weeks ago, so the overall risk must not have been that bad.


It is likely not that the risk two years ago was less. It is much more likely that two years ago the tools and knowledge base to analyize the risk were not available.

smilingsmeagol wrote:I will proceed to get a second opinion on my case and give an update.


You could probably shop for a doc who will do the surgery, but that will not change the fact that you are very likely going to have very serious problems if you decide to have cornea-based refractive surgery.

It's time to consider alternatives like Intacs (which are removable) or accept that you are not a candidate for any type of refractive surgery.
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Postby smilingsmeagol » Sat Mar 17, 2007 8:35 pm

"It is likely not that the risk two years ago was less. It is much more likely that two years ago the tools and knowledge base to analyize the risk were not available. "


>> A point of clarification, he was willing to do the procedure 2 weeks ago, not 2 years ago. He got no new information in the latest battery of tests, my condition was exactly the same. He gave no indication that there was new knowledge on the technology or procedure in the last 2 weeks.

"You could probably shop for a doc who will do the surgery, but that will not change the fact that you are very likely going to have very serious problems if you decide to have cornea-based refractive surgery. "

>>I am not intending to shop until a doctor says he will do it, I agree that would be reckless. I will shop around until a dr tells me what my risks are. The most concerning part of the whole discussion is that the dr did not want to commit to telling me the relative magnitude of the risk, just that there is a risk. Everyone who has ever had refractive surgery has had risk. I'm ok doing a procedure if the risk is relatively minor, but I dont want to do a procedure unless I know that relative magnitude is. There was no possibility of making an informed consent on my end.
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Postby LasikExpert » Sun Mar 18, 2007 2:18 am

[quote="smilingsmeagolA point of clarification, he was willing to do the procedure 2 weeks ago, not 2 years ago. He got no new information in the latest battery of tests, my condition was exactly the same. He gave no indication that there was new knowledge on the technology or procedure in the last 2 weeks.[/quote]

That is very different. Obviously, after better analysis of the same data the doctor came to a different conclusion. A better one, in my opinion.

I don't know that anyone will be able to say, "You have a 87% probability of night vision problems that will limit your ability to drive within one hour of sundown," or anything nearly as specific. Your high HOA are out of the norm. The norm is what is reasonably predictable. Since your HOA are above the norm, then you would seem to have an above the norm probability of an unexpected outcome. Microsurgery on biological tissue is not absolutely precise, especially when you start outside the norm.
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Postby smilingsmeagol » Fri Mar 30, 2007 8:30 pm

Update: I just spoke with a reputable doctor in Northern California and faxed him over my test results. This doctor performed the procedure with a contact of mine who is an opthamologist, so I know he is good. Plus he has done over 40,000 surgeries. He, at an earlier time cleared me completely for LASIK and Refractive Surgery.

After reviewing my information, he mentioned that he sees no reason why having Higher Order Aberrations at my level would cause any more risk. He feels that I am an excellent candidate and is confused as to why my previous doctor turned me down. Keep in mind that I had a full work up by both doctors.

I am attempting to get a 3rd opinion to see what the consensous is.
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Postby smilingsmeagol » Fri Mar 30, 2007 10:51 pm

Update: I just spoke to 2 more doctors. They both said that my eyes are a good candidates. Another reputable doctor said that my eyes are a "slam dunk". He mentioned that the machine used by the first doctor was a "Flying Spot" Alcon laser. His machine is a Visex laser, which can handle the higher order aberrations better when it comes to custom wavefront.

My question is, is there documentation comparing the 2 machines? Are the differences between the Alcon (Flying Spot) vs Visex lasers well known?
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Postby LasikExpert » Sat Mar 31, 2007 12:25 am

Every manufacturer will say their laser is better. Every doctor will say his/her laser is the best. The FDA has details on each. For the majority of patients, the probability of a good outcome is about the same between the Alcon LADARVision, Visx S4, Bausch & Lomb Zyoptix, and WaveLight Allegretto Eye-Q. For some patients, one may be better than the other.
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