Beitrag
von Dr. med. Ron Lehnert » 14.12.2006, 18:40
Hallo Nova!
Die Hornhaut schafft keine komplette Wundheilung nach einer LASIK. Eine aktuelle Studie in einem renommierten Journal hat gezeigt, dass der Flap an sich nur noch 2,8% und der Flaprand 28,1% Reißfestigkeit im Vergleich zu einer nicht-operierten Hornhaut bieten. Die Studie berichtet auch, dass ein Chirurg einen Flap noch nach 11 Jahren angehoben hat.
1: J Refract Surg. 2005 Sep-Oct;21(5):433-45.
Cohesive tensile strength of human LASIK wounds with histologic,
ultrastructural, and clinical correlations.
Schmack I, Dawson DG, McCarey BE, Waring GO 3rd, Grossniklaus HE, Edelhauser HF.
Emory Eye Center, Emory University School of Medicine, Atlanta, GA 30322, USA.
PURPOSE: To measure the cohesive tensile strength of human LASIK corneal wounds.
METHODS: Twenty-five human eye bank corneas from 13 donors that had LASIK were
cut into 4-mm corneoscleral strips and dissected to expose the interface wound.
Using a motorized pulling device, the force required to separate the wound was
recorded. Intact and separated specimens were processed for light and electron
microscopy. Five normal human eye bank corneas from 5 donors served as controls.
A retrospective clinical study was done on 144 eyes that had LASIK flap-lift
retreatments, providing clinical correlation. RESULTS: The mean tensile strength
of the central and paracentral LASIK wounds showed minimal change in strength
over time after surgery, averaging 2.4% (0.72 +/- 0.33 g/mm) of controls (30.06
+/- 2.93 g/mm). In contrast, the mean peak tensile strength of the flap wound
margin gradually increased over time after surgery, reaching maximum values by
3.5 years when the average was 28.1% (8.46 +/- 4.56 g/mm) of controls.
Histologic and ultrastructural correlative studies found that the plane of
separation always occurred in the lamellar wound, which consisted of a
hypocellular primitive stromal scar centrally and paracentrally and a
hypercellular fibrotic stromal scar at the flap wound margin. The pathologic
correlations demonstrated that the strongest wound margin scars had no
epithelial cell ingrowth-the strongest typically being wider or more
peripherally located. In contrast, the weakest wound margin scars had epithelial
cell ingrowth. The clinical series demonstrated the ability to lift LASIK flaps
without complications during retreatments up to 8.4 years after initial surgery,
correlating well with the laboratory results. CONCLUSIONS: The human comeal
stroma typically heals after LASIK in a limited and incomplete fashion; this
results in a weak, central and paracentral hypocellular primitive stromal scar
that averages 2.4% as strong as normal comeal stroma. Conversely, the LASIK flap
wound margin heals by producing a 10-fold stronger, peripheral hypercellular
fibrotic stromal scar that averages 28.1% as strong as normal comeal stromal,
but displays marked variability.
PMID: 16209440 [PubMed - indexed for MEDLINE]
