Questions and Answers on “Managing visual loss after LASIK”

(Marc Michelson, MD)

and

“New LASEK technique ”

(Herman Sloane, MD)

Moderator: We have time for a few last questions. We have a question for Dr Michelson. How do you measure your exact position with reference to the topography that you showed under the laser?

Marc Michelson, MD: There are two guidelines that I use. Number one is the topography itself, and you know that this is broken down into millimeters and you can actually gauge approximately how far from the center of the pupil axis you want to go, in which direction. The other thing you use are your visuals on your stromal surface, and you can pretty well match. When you lift a flap, you are going to visualize bumps and irregularities, and 90% of the time you are going to correlate what you see visually with what you see topographically. Remember, that topography is turned upside down, the way you are looking at it on the chart. It now simulates the surgical view of the eye. And, if you have a vector that is shooting off at about 30° to a hill that is about a millimeter away on topography, and you visualize that where you think it is going to be, often you can actually see a little stromal elevation. This guides you right to where you want to treat. It is important when you do a 2-mm spot PTK treatment that no one spot goes back into the same position of the previous spot. Because you want to randomly scatter these spots to knock the hill down. The other important thing is that your foot has to selectively deliver one or two spots at a time. You are not hitting in rapid sequence. So, it is very critical that you are really hitting, and you have to practice doing this before you take a patient to the laser, by which I mean, how you can deliver a spot or two at a time. This is also very critical so that you don’t overdo it or don’t treat in the wrong area. I know this isn’t an exact science, but these are the only patients on whom I have done this technique, and I haven’t had an overcorrection or a mistreatment yet.

Moderator: Another question is: how long do the people performing LASEK procedures wait to replace the LASEK epithelial flap? How long do you wait after the treatment before you replace the epithelium?

Herman Sloane, MD: Immediately.

Wavefront and Emerging Refractive Technologies, pp. 197–198

Proceedings of the 51st Annual Symposium of the New Orleans Academy of Ophthalmology, New Orleans, LA, USA, February 22-24, 2002

edited by Jill B. Koury

© 2003 Kugler Publications, The Hague, The Netherlands

Moderator: And then a follow-up question to that is: do you expect any problems at the junction between the two epithelial flaps centrally, such as duplicated basement membrane material, or any abnormalities or irregularities on the surface?

Dr Sloane: I thought about this and watched them heal, and occasionally I get a little epithelial suture line just as you might after an abrasion, but it is relatively short-lived. One of the things I really liked about Dr Vinciguerra’s presentation, which I will probably incorporate when I go home, is his paracentral incision. Because, when there is a suture line that bisects the pupil like that, of course you have to wait a couple more days for the vision to get even better. Usually, it is no more than a couple of lines of vision that it is responsible for, so it will be about 20/40, 20/30, and when that thing goes away, they will drop down to 20/20, but I like that paracentral incision that Paolo is using.

Daniel S. Durrie, MD: Herman, have you been able to decrease the number of days needed with a contact lens with this technique?

Dr Sloane: The magic question. I wish somebody would be able to do that. It is still three to four days for me, even though, theoretically, I thought this would be faster. Well, it’s still three to four days. But, actually it is pretty reproducible. When I was doing the Camellin procedure, I don’t know about you, Dan, but sometimes it would be considerably longer than three to four days. So, there is a range there that is tighter, more precise, but it is still three to four days.

Moderator: Another follow-up question about LASEK: is anyone using collagen shields (this says with gentamicin) instead of contact lenses?

Dr Durrie: Yes, they don’t work. They definitely do not work. They suck on. We did a series of them and they all came off within an hour or two afterwards. It was a nice idea, but it doesn’t work.

Paolo Vinciguerra, MD: We use some soluble collagen shields. The problem is that they start to make a hole in the center, sometimes the periphery, so, yes, on an even surface over the epithelium, it was very bad.

Moderator: Does anyone use air-drying or compressed air to stick down the LASEK flap? Is that better or faster?

Dr Durrie: I do actually. I use oxygen running at two liters. I put it in position, use it just until it kind of shrink-wraps it, then irrigate again and put the contact lens on, but I have never done it both ways to see whether it is really helping or not, it was just something else to do, but I haven’t proved it.

Dr Vinciguerra: We tried bilaterally to do one way, but no difference.

Index of authors

Applegate, R.A., 17, 189

Camesasca, F.I., 27, 69, 167

Durrie, D.S., 55, 65

Ginis, H.S., 181

Kalyvianaki, M.I., 181

Kezirian, G.M., 127

Koury, J.B., vii

Krueger, R.R., 43, 117, 159

Naoumidi, I.I., 181

Pallikaris, I.G., 181

Schallhorn, S., 97

Slade, S.G., 39, 107

Stonecipher, K.G., 87, 127

Vinciguerra, P., 17, 69, 167

Williams, D.R. 3, 147