LASIK in 2000, Night vision problems

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LASIK in 2000, Night vision problems

Postby GeneralPatientInquiry » Tue May 30, 2006 11:35 pm

I first had LASIK with Dr C in Chicago in March of 2000, unknown to me at the time I had/have large pupils. They get approx 7.5mm each. He said I was "the perfect canidate" and so I went ahead. Before the operation I was approx -4.50 in both eyes, and after I was almost 20/20. But I had bad starbursting, haloes, & glowing around lights in low light/night conditions. This went on and did not change, and in 2003 I had custom wavefront "off label" with Dr S in CA.

It did help improve my vision, but the night/low light problems still occur due to my pupil size. I'd say they are approx 50% better with the custom treatment, but still affect my vision. My treatment zone was 6.5mm with a blend of 1.25, but Dr S says that the 1.25 blend "is all the way around" so that its 2.50, giving me a total area of 9.00mm. I don't understand how the 1.25 blend is doubled though, and I still feel my actual ablation zone should be larger. If I put on the dome light of my car at night and look at it 95% of the side effects are gone, so I know my issue is related directly to pupil size. I'm not sure what my current corneal thickness is.

Dr S said recently in an e-mail that PRK on top of the LASIK runs the risk of haze, which I have read a little about. But he says that also I that would ablate too much tissue, I thought PRK uses less tissue? Also if he corrected to 9mm with the blend (6.5mm main area), could he go to say 7.5mm, then do a 1.5mm blend? I know when I saw him he said a lot would depend on how big my original flap was, but if he supposedly went out to 9mm with the blend, could he do a treatment of 7.5m and then do a short blend? Or would adding that 1mm ablate a lot more tissue?

Dr S is a good Dr, and a straight shooter (not like the 1st doctor!) but he seems a little scatter-brained in his responses to my e-mails. I'm sure its because hes a busy man, and has a lot going on, but I want to know what (if any) option I have. I know about Alphagan, and have tried it before the 2nd surgery, but it was too strong and made me groggy and cotton-mouthed. I also tried Alphagan P which did not have the side effects, but was not as effective. And again I have not tried any Alphagan after the 2nd surgery with Dr S.

I would really appreciate knowing my options, or other doctors who have dealt with similar cases. Like can custom wavefront go wider? Again Dr S said all wavefront is 6.5mm with a blend out to save tissue. What about PRK on top of my LASIK? Again I read some brief article where a European Dr recommended against it.
This post is a reprint of a previously requested inquiry received by USAEyes.org via email.
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Postby LasikExpert » Wed May 31, 2006 12:57 am

I'm sorry to hear of your difficulties. Yours is one of the more difficult situations.

I’m sure you understand this, but for the benefit of others I’ll discuss the primary issue involved.

Lasik does not treat the entire cornea. A central section, commonly 6.5mm in diameter, is fully corrected. An additional under-treated transition zone reaching from the fully corrected optical zone to the untreated surface reduces the probability of vision aberrations. Optical zone is full correction. Transition zone is undercorrected.

In low light environments your pupils become large and extend into the transition zone. Light passing through the transition zone reaches the retina and is "seen", but is out of focus. Because a portion of the light being seen is poorly focused, vision quality is poor, often presenting with haloes around light sources or starbursting from light sources.

In well lit environments or with the use of special eye drops, your pupil becomes smaller and only light passing through the optical zone reaches the retina and is seen. Because all light through the optical zone is properly focused, vision is clear.

One would expect that predicting who would have night vision problems would be pretty easy with just a few measurements, but it is not. Some patients have pupils much larger than their optical zones and yet have no night vision problems. Pupil size alone is an unreliable predictor of night vision problems. For details, read Lasik Pupil Size

Your Complex Wavefront Retreatment (CWR) surgery in 2003 would have been primarily to reduce the higher order aberrations affecting vision, however CWR can only treat a 6.5mm optical zone and the blend would not utilize wavefront data. Your pupils at 7.50mm would cover a large under-treated area. It is not surprising that CWR improved your vision, neither is it surprising that you continue to have night vision problems.

I’m not sure what is meant by the “all the way around” statement either. The optical zone is 6.5 and the transition is an additional 1.25 so the total diameter of treatment is 6.5 + 1.25, or 7.75mm.

Even a small amount of light can constrict the size of the pupil enough that only the optical zone is used. The use of the topical eye drops Pilocarpine and Alphagan P can constrict the pupils as well. Alphagan P is much more benign than Pilocarpine and does not constrict the size of the pupils so very much. If approved by your doctor, I suggest you give it another try.

PRK on the existing Lasik flap is becoming more popular. This has the advantage of keeping the untouched thickness of the cornea at maximum, and a surface ablation will be able to provide a more nuanced result. Yes, ablation on the Lasik flap has a higher incidence of corneal haze, however the use of Mitomycin C during surgery has reportedly reduced the probability to just about zero. Mitomycin C is a strong medicine that is probably best avoided when possible, but is most appropriate when needed.

In your situation the amount of tissue that would need to be removed is undoubtedly small. The thickness of the average flap would likely be more than enough even with a large ablation zone.

You would still have an optical ablation zone limitation if you elected for a wavefront-guided ablation. Conventional can be up to 11.0mm, but wavefront is still limited to 6.5mm.

Every complicated case is...well...complicated. Each is unique. It would be very difficult for me to go beyond generalizations. You have a good surgeon in Dr. S, however it would probably be best to find someone a little more convenient. You would also have the advantage of a second opinion. I recommend you contact a corneal specialist at a nearby teaching hospital, or at your request I could make a referral to someone in Chicagoland.
Last edited by LasikExpert on Fri Jun 16, 2006 3:12 am, edited 1 time in total.
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Postby GeneralPatientInquiry » Fri Jun 02, 2006 7:48 pm

Thank you for your response, I did get a hold of Dr K who is in IL, and was recommended by the website. He called me about a week later after I e-mailed him, and he seems very helpful. I have an appointment to go and see him on the 9th of June, so he can get a look at my eyes for himself. I still don't under stand the blend of "1.25 all the way around" either, but I asked Dr K also, and he said the same thing as Dr S. I will just have to wait and see what Dr K has to say, and see what future technology holds. I did check with Dr S's office, and before my custom treatment I had 600 microns in one cornea, and the other was 560 microns, and the custom treatment used only about 40 microns, so my corneas have enough thickness. I still have no doubt that if my actual treatment zone is at least 7.5mm my night vision will get a lot better, I do think no matter how big the treatment zone is I will still have a little bit of aberrations. Well, I'm going to give Dr K a shot and go from there, thanks again.
This post is a reprint of a previously requested inquiry received by USAEyes.org via email.
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Joined: Tue May 30, 2006 8:00 pm

Postby LasikExpert » Fri Jun 02, 2006 7:57 pm

Getting local help will undoubtedly be easier on you and your pocketbook. I'm glad that a doctor who has been certified by our organization is nearby and available to help you.

I agree that if your optical treatment zone is made to be equal to your naturally dilated pupil that you would probably not have the problems you are experiencing today, however it would have been difficult to predict that a smaller optical ablation zone would cause your problems. That is the part about pupil size that is often difficult to comprehend. The difference is between predicting who will have night vision problems and how to treat night vision problems if they actually occur. Pupil size alone is a poor preoperative predictor of night vision problems, but when someone actually develops night vision problems postoperatively, pupil reduction (or ablation zone enlargement) will often reduce symptoms.

As we state in the cited article on Lasik and pupil size issues, the most conservative route would be to make the optical ablation zone equal to or greater than the size of the naturally dilate pupil, however due to other considerations that may not be possible.
Glenn Hagele
Volunteer Executive Director
USAEyes

Lasik Info &
Lasik Doctor Certification

I am not a doctor.
LasikExpert
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Posts: 3309
Joined: Fri May 12, 2006 6:43 am
Location: California


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