LASEK and Epi-LASEK are "no Knife " operations.
The cornea has several layers and the top one, the "epithelium" has to be removed prior to firing the laser. This is because this tissue laser is very active and replaces itself every couple of days. It is 50 microns deep and if we just lasered this, then the tissue would remodel and reverse any effect. This has to be removed prior to surgery and can be done in several ways. These are scraping with a blunt blade, using an electric toothbrush- like instrument, using 17% alcohol (like Martini) or just lasering through the epithelium. I have tried all of these methods and prefer the alcohol one. This is because it reduces the risk of haze very markedly and also does not kill the epithelium, which can be replaced back onto the cornea, a bit like lasik. We originally called this "epiflap" and it is also known as LASEK (laser assisted epithelial keratomileusis) as it was independently thought up in Optimax Manchester by Sunil Shah and in Italy by Massimo Camellin, who uses the latter term. It is also called EPI-LASEK. Using a machine similar to a microkeratome to remove the epithelium is called EPI-LASIK. Preliminary reports seem to indicate that whether the epithelium is removed by alcohol or by a machine gives very similar results.
- LASEK Picture 1 LASEK Picture 1
- LASEK Picture 2 LASEK Picture 2
- LASEK Picture 3 LASEK Picture 3
- LASEK Picture 4 LASEK Picture 4
- LASEK Picture 5 LASEK Picture 5
- LASEK Picture 6 LASEK Picture 6
Picture 2: 18% alcohol is put onto the cornea for 35 seconds by dropping it into a sort of "well" placed on the anaesthetised eye
- "Electron Microscope" Picture 1 "Electron Microscope" Picture 1
- "Electron Microscope" Picture 2 "Electron Microscope" Picture 2
Electron Microscope Picture 2: Electron microscope view of a human epithelium after 30 seconds of 17% alcohol. All the intracellular structures are intact, indicating probable viability. Recent work in Italy has shown that if the alcohol is mixed with Balanced Salt Solution (BSS), then 70% of the epithelial cells remain viable rather than 45% with pure water and alcohol. We have now switched to this mixture.
Speed of recovery with LASEK
- "Speed of Recovery" Picture 1 "Speed of Recovery" Picture 1
- "Speed of Recovery" Picture 2 "Speed of Recovery" Picture 2
- "Speed of Recovery" Picture 3 "Speed of Recovery" Picture 3
- Unaided vision right after the operation (Our charts use the continental spacing of 1.2, 1.0, 0.8, 0.63, 0.5 which corresponds to the British 6/5, 6/6, 6/7.5, 6/10 and 6/12. ......6/10 is driving standard and 6/6 is "20/20" vision)
- Unaided vision at day 4 post-op
- Unaided vision at day 7 post-op
How safe is PRK / LASEK for higher prescriptions?
This is a small group of myopes of between -6 and -10 treated by LASEK (CVA = corrected visual acuity). This graph is of lines lost or gained on the Snellen chart. (See Lasik Audit for explanation). This shows that LASEK is comparable in safety to LASIK for these levels of myopia, although it takes longer to get there.
Results: with LASEK are the same as LASIK. (It is the same lasering in each but on a different part of the cornea so one would expect them to be the same). Look at the LASIK results charts to see more details of this.
Cooling: There are a number of reports now about doing PRK at a low temperature - similar to a fridge. This seems to reduce haze risks even further and one Japanese group claims to be doing PRK up to -20 Dioptres with no problem! We now routinely cool the cornea before and after treatment with refrigerated drops. This also seems to lessen any post-op pain.
Mitomycin-C: This is a cytotoxic drug that has been used in drop form on the eye in children with glaucoma for some time. It has also been used over the last 4 years by some groups to get rid of persisting "haze". This is done by initially removing the haze with the laser or mechanically. Then, using a sponge, a very diluted form of the drug is placed onto the cornea for a couple of minutes. This seems to work well, and there have been no reported long term problems after 4 years. I have used this drug for 5 years without any problems and it seems to work well. I also use it prophylactically in very high primary LASEK's over -8 . However, this use of mitomycin-C is totally "off label" and really done at the patient's risk.