[Laser epithelial keratomileusis (LASEK): histological investigation for vitality of corneal epithelial cells after alcohol exposure].
BACKGROUND
Laser epithelial keratomileusis (LASEK) is a new surgical procedure to treat myopia. An epithelial flap is created after the exposure to 20 % alcohol and following the laser ablation the epithelium is repositioned to its original location. The advantage of LASEK is that the ablated corneal surface is covered by a full thickness epithelium immediately after surgery. It is hypothesised that this epithelial coverage inhibits the wound healing response of the cornea. However, this concept will only work if the epithelial cells are still vital after the exposure to alcohol.


METHODS
The vitality of the corneal epithelial cells was investigated in 6 human cadaver eyes after the exposure to 20 % alcohol over 15 to 60 s. The vitality of the corneal epithelial cells was assessed by soaking the specimen in a 0.1 % trypan blue solution and incubated at 37 degrees C for 2 min. After a wash with BSS the specimen were re-incubated at 37 degrees C for 30 min in culture medium. After one more wash with BSS the cells were observed with a standard light microscope. Cells which retained the blue colour would be dead and vital cells would appear clear. Light microscopy and transmission electron microscopy was used to detect morphological changes.


RESULTS
Mainly vital corneal epithelial cells were seen for an alcohol exposure time of up to 30 s. In particular the basal epithelial cells appeared alive. With a exposition time of 60 s most cells were dead.


CONCLUSIONS
In LASEK the exposure time of 20 % alcohol is between 20 and 30 s. Based on our results we can conclude that after such exposure time most cells are alive, which is essential for the postoperative wound healing response.
Dreiss
Alexandra K
AK
The Rayne Insitute, Departmen of Ophthalmology, St. Thomas' Hospital, London. alexandradreiss@hotmail.com
Winkler von Mohrenfels
Christoph
C
Gabler
Bernhard
B
Kohnen
Thomas
T
Marshall
John
J
Lohmann
Chris P
CP
D002452:Cell Count; D002470:Cell Survival / Q000187:drug effects*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D019573:Epithelium, Corneal / Q000187:drug effects* / Q000473:pathology; D000431:Ethanol / Q000633:toxicity*; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D008854:Microscopy, Electron; D013997:Time Factors; D014945:Wound Healing / Q000187:drug effects
D000431:Ethanol