Read our news and take a look at Q&A with Dr. Chynn.

Thoughts on No-Touch-Prk modes on some lasers

i used to use MMC for Rx above -5, then had some late (>3 mo out) haze for -4, and rarely had it for -3 something

so i reduced my limit for MMC (since it is really perfectly safe if diluted properly and applied on a sponge) to > -3
this depends where you are, like if in an area with more sun/UV/wind/etc scarring is more likely, so need MMC more
i tried through epi PRK years ago, i’m on a VISX, there is an (old) software setting for this (“laser-scrape”)
the reason we called it “laser scrape” is that you always get a ring of residual epithelium that you then need to scrape off
which defeats the purpose of using the laser to remove the epi (over Amoilis brush) to make it less traumatic/cleaner
the reason again for this optically is the laser becomes more tangential/less orthogonal to the cornea towards the periphery
so the efficiency is decreased, so you get central breakthrough before the periphery
i understand that modern software algorithms add energy to the periphery to try to obtain uniform epi removal/breakthrough
however, there still aren’t great methods that are always used to measure preop epi thickness (preop OCT isn’t common)
so then we are reduced to visualizing removal by looking for visual breakthrough
i also think that the energy of the eximer on the epi is probably imparted somewhat onto the underlying cornea
so that you are probably adding energy/trauma to the underlying cornea while you are doing a laser epi removal
which is another reason why you might want to use MMC for -3, especially if you are emplying laser-scrape
so my suggestion based on the above to avoid haze in future cases would be to:
1. prechill the cornea with frozen BSS preop
2. apply chilled BSS on a sponge after epi removal and before corneal ablation
3. add MMC after ablation
4. add oral steroids postop + Vit C + UV protection
fundamentally, i have had excellent results after EtOH-assisted PRK/LASEK, so don’t know why you need to laser scrape
what is the rationale for using laser-scrape over EtOH-assisted epi removal?
it seems to me that the latter is actually less traumatic, and less prone to scarring (at least in my hands)
although the patients do seem to like the sound of “no-touch/all-laser” from a marketing perspective
eager to hear your thoughts

Write a Comment

Research Methods Rigor

Minas, Clive, et al First of all, I’d like to congratulate Minas on finding an article I had published in Arch Ophth over …

Nursing and LASIK

Q: I think a lot of this can be simply answered by asking ourselves the following question: If your wife/sister/daughter …

ASA retreat

Dear David et al Sorry for my delay in responding. I’m visiting my girlfriend’s family in a rural part of Bulgaria wo …