Short-term impact of corticosteroids on hyaluronan and epithelial hyperplasia in the rabbit cornea after photorefractive keratectomy.
OBJECTIVE
To investigate the impact of corticosteroids on subepithelial hyaluronan deposition and corneal epithelium thickness in the first 10 days after photorefractive keratectomy (PRK) and to analyze a possible contralateral effect of corticosteroids.


METHODS
Thirty-two New Zealand white rabbits were assigned into two groups and had a transepithelial 5.0-mm diameter, 8.00-diopter myopic PRK performed on one eye. The corticosteroid treatment group (16 animals) received 0.1 mL of methylprednisolone 4% subconjunctivally on the operation table, followed by 0.1% dexamethasone eye drops six times a day during the postoperative period. The sodium chloride (NaCl) treatment group received topical isotonic NaCl eye drops six times a day. In each treatment group, eight animals were killed after 3 and 9 days, respectively. The harvested specimens were stained for hyaluronan and the epithelial thickness was measured.


RESULTS
In contrast to the epithelial thickness, the subepithelial hyaluronan did not show a significant increase during the observation period. The corticosteroid treated group showed at both time-points significantly less subepithelial hyaluronan formation as well as a significantly thinner epithelium, when compared with the NaCl-treated group. At 9 days, the corticosteroid-treated group showed a mild epithelial hyperplasia in only one of eight eyes, whereas this was a common finding in the NaCl-treated group. We detected no hyaluronan deposits in any contralateral-untreated eye, and the epithelial thickness did not differ significantly between any of the four contralateral-untreated eye groups.


CONCLUSIONS
Corticosteroid medication during the first 10 days after operation reduces the amount of subepithelial hyaluronan production and inhibits the epithelial proliferation, and epithelial hyperplasia is prevented. Neither a contralateral hyaluronan deposition nor a contralateral corticosteroid effect could be detected.
Weber
B A
BA
St Erik's Eye Hospital, Karolinska Institute, Stockholm, Sweden. weber.ba@bluewin.ch
Gan
L
L
Fagerholm
P P
PP
D000287:Administration, Topical; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage*; D002455:Cell Division / Q000187:drug effects; D003315:Cornea / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D003907:Dexamethasone / Q000008:administration & dosage; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005260:Female; D005938:Glucocorticoids; D006820:Hyaluronic Acid / Q000378:metabolism*; D006965:Hyperplasia / Q000517:prevention & control; D054018:Lasers, Excimer; D008775:Methylprednisolone / Q000008:administration & dosage; D009216:Myopia / Q000601:surgery; D018903:Photorefractive Keratectomy; D011817:Rabbits
D000893:Anti-Inflammatory Agents; D005938:Glucocorticoids; D003907:Dexamethasone; D006820:Hyaluronic Acid; D008775:Methylprednisolone