Wound healing response in the presence of stromal irregularities after excimer laser treatment.
OBJECTIVE
To trace the fate of stromal irregularities after excimer laser treatment and to increase our knowledge of the reasons why surface irregularities in the ablation bed cause inferior postoperative results.


METHODS
Twelve New Zealand White rabbits received a transepithelial photoablation to a preset depth of 60 microm. An electron microscopy specimen grid was then placed on the denuded stroma and another 20 microm ablation was applied in order to produce surface irregularities. Another six rabbits received a plano transepithelial photoablation to a preset depth of 80 microm. The treated corneas were harvested at various timepoints and differentially further processed for microradiography, hematoxylin-eosin -, hyaluronan (HA)- and leukocyte protein L1 staining.


RESULTS
In the grid treated corneas the subepithelial mesh pattern is clearly discernible after 1 week, and after 4 weeks it is replaced by a subepithelial layer containing HA and water. The thinning of this layer between 1 and 12 weeks is statistically significant (p<0.05). After 4 and 8 week the plano treated corneas only exhibit some subepithelial HA- and water accumulation. After 1 day the grid treated corneas show an extensive stromal infiltration of leukocytes. In the plano treated corneas the leukocytes mainly remain on the surface.


CONCLUSIONS
During the healing process stromal irregularities are flattened, leaving a homogeneous zone with increased water content. This subepithelial layer is rarefying as new subepithelial tissue is forming. Postablational irregularities induce a more pronounced healing reaction when compared to a smooth ablation surface. Leukocyte infiltration seems to play a role in this process.
Weber
B A
BA
St. Erik's Eye Hospital, Karolinska Institute, Stockholm, Sweden; Dept. of Ophthalmology, University Hospital, Linköping, Sweden. beat.weber@bluemail.ch
Gan
L
L
Fagerholm
P
P
D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism; D002465:Cell Movement; D003319:Corneal Stroma / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D005260:Female; D007124:Immunoenzyme Techniques; D054018:Lasers, Excimer; D039841:Leukocyte L1 Antigen Complex; D007962:Leukocytes / Q000378:metabolism / Q000473:pathology; D008562:Membrane Glycoproteins / Q000378:metabolism; D019006:Neural Cell Adhesion Molecules / Q000378:metabolism; D018903:Photorefractive Keratectomy; D011817:Rabbits; D013997:Time Factors; D014945:Wound Healing
D000954:Antigens, Surface; D039841:Leukocyte L1 Antigen Complex; D008562:Membrane Glycoproteins; D019006:Neural Cell Adhesion Molecules