Keratocyte apoptosis and corneal antioxidant enzyme activities after refractive corneal surgery.
OBJECTIVE
Refractive corneal surgery induces keratocyte apoptosis and generates reactive oxygen radicals (ROS) in the cornea. The purpose of the present study is to evaluate the correlation between keratocyte apoptosis and corneal antioxidant enzyme activities after different refractive surgical procedures in rabbits.


METHODS
Rabbits were divided into six groups. All groups were compared with the control group (Group 1), after epithelial scraping (Group 2), epithelial scrape and photorefractive keratectomy (PRK) (traditional PRK: Group 3), transepithelial PRK (Group 4), creation of a corneal flap with microkeratome (Group 5) and laser-assisted in situ keratomileusis (LASIK, Group 6). Terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick-end labelling assay (to detect DNA fragmentation in situ) and light microscopy were used to detect apoptosis in rabbit eyes. Glutathione peroxidase (Gpx) and superoxide dismutase (SOD) activities of the corneal tissues were measured with spectrophotometric methods.


RESULTS
Corneal Gpx and SOD activities decreased significantly in all groups when compared with the control group (P<0.05) and groups 2, 3 and 6 showed a significantly higher amount of keratocyte apoptosis (P<0.05). Not only a negative correlation was observed between corneal SOD activity and keratocyte apoptosis (cc: -0.3648) but Gpx activity also showed negative correlation with keratocyte apoptosis (cc: -0.3587).


CONCLUSIONS
The present study illustrates the negative correlation between keratocyte apoptosis and corneal antioxidant enzyme activities. This finding suggests that ROS may be partly responsible for keratocyte apoptosis after refractive surgery.
Bilgihan
K
K
Department of Ophthalmology, Gazi University Medical School, Ankara, Turkey. bilgihan@med.gazi.edu.tr
Bilgihan
A
A
Adiguzel
U
U
Sezer
C
C
Yis
O
O
Akyol
G
G
Hasanreisoglu
B
B
D000704:Analysis of Variance; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D017209:Apoptosis; D003315:Cornea / Q000201:enzymology / Q000473:pathology*; D005979:Glutathione Peroxidase / Q000378:metabolism; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer; D018903:Photorefractive Keratectomy; D011184:Postoperative Period; D011817:Rabbits; D054140:Refractive Surgical Procedures; D013482:Superoxide Dismutase / Q000378:metabolism
D000975:Antioxidants; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase