Mitomycin C, ceramide, and 5-fluorouracil inhibit corneal haze and apoptosis after PRK.
OBJECTIVE
To investigate the effects of mitomycin C (MMC), ceramide, and 5-fluororacil (5-FU) on haze after photorefractive keratectomy (PRK) and exposure to ultraviolet B (UVB) radiation.


METHODS
The right eyes of 42 New Zealand white rabbits were treated with PRK to correct -10 diopter with a 5-mm optical zone. Sponges soaked in 0.02% MMC, 10 or 40 micromol/L ceramide, or 0.5% 5-FU were applied to the right eyes of 6 rabbits each, and a tarsorrhaphy was performed. Eight weeks after complete healing, topical 0.02% MMC or 0.5% 5-FU was applied twice daily to the right eyes of 6 rabbits that had previously received PRK but no topical medication. The control group of 6 rabbits was treated only with PRK. Three weeks after PRK, all the laser-treated eyes were exposed to 100 mJ/cm UVB radiation. Corneal haze was assessed biomicroscopically every 2 weeks using the Fantes scale. Eyes were enucleated 2, 7, and 13 weeks after PRK, and tissue specimens were stained with hematoxylin and eosin and with Apostain.


RESULTS
Corneal haze was observed in all rabbits after PRK and was aggravated by UVB irradiation. When applied immediately after PRK, MMC induced corneal opacity and apoptosis of keratocytes, but, at later times, this reagent significantly suppressed opacity, Apostain-positive keratocytes and reactivation of keratocytes, even after UVB irradiation. In contrast, ceramide and 5-FU suppressed corneal opacity after PRK, but this effect was not sustained after UVB irradiation.


CONCLUSIONS
MMC is a potent inhibitor of haze induced by PRK and UVB irradiation. Throughout the process of corneal wound healing, the severity of apoptosis and reactivation of keratocytes was closely correlated with haze formation.
Kim
Tae-im
TI
Department of Ophthalmology, University of Ulsan, College of Medicine, Asan Medical Center, Seoul, Korea.
Lee
Sun Young
SY
Pak
Jhang Ho
JH
Tchah
Hungwon
H
Kook
Michael S
MS
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002518:Ceramides / Q000627:therapeutic use*; D003315:Cornea / Q000473:pathology / Q000528:radiation effects / Q000601:surgery; D003318:Corneal Opacity / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D005472:Fluorouracil / Q000627:therapeutic use*; D054018:Lasers, Excimer; D016685:Mitomycin / Q000627:therapeutic use*; D018903:Photorefractive Keratectomy; D011183:Postoperative Complications / Q000517:prevention & control*; D011817:Rabbits; D014466:Ultraviolet Rays; D014945:Wound Healing / Q000187:drug effects
D002518:Ceramides; D016685:Mitomycin; D005472:Fluorouracil