Comparison of corneal wound-healing response in photorefractive keratectomy and laser-assisted subepithelial keratectomy.
OBJECTIVE
To evaluate in a rabbit model the differences in cellular and matrix stromal response in low and high attempted corrections between photorefractive keratectomy (PRK) and laser-assisted subepithelial keratectomy (LASEK).


METHODS
Louisiana State University Health Sciences Center, Department of Ophthalmology and Neuroscience Center, New Orleans, Louisiana, USA.


METHODS
Twenty-four eyes of 12 New Zealand albino rabbits were used. Photorefractive keratectomy was performed in 1 eye and LASEK was performed in the contralateral eye of all rabbits. In 5 animals, a low refractive correction (--3 diopters [D]) was attempted. In the other 5 rabbits, a high refractive correction (--7 D) was attempted. Two rabbits served as controls. The animals were followed for 7 days, after which they were humanely killed. The eyes were enucleated and processed for histopathology and immunohystochemical analysis.


RESULTS
All eyes showed an inflammatory response in the anterior stroma adjacent to the ablated area, with greater inflammatory cell infiltration with higher attempted corrections. Similar keratocyte apoptosis was found with low attempted corrections in PRK-treated and LASEK-treated eyes. However, there was a significant increase in keratocyte apoptosis in the PRK group at higher attempted corrections. Increased transformation to myofibroblasts and synthesis of chondroitin sulfate were observed adjacent to the ablated stroma in all eyes. With low corrections, no differences were observed between LASEK-treated and PRK-treated eyes. With higher attempted corrections, there was a significant increase in myofibroblast transformation and chondroitin sulfate synthesis in the PRK group. An irregular and discontinued collagen IV component of the epithelial basement membrane was observed in all PRK-treated and LASEK-treated eyes regardless of the attempted correction.


CONCLUSIONS
At higher attempted corrections, LASEK-treated eyes showed less keratocyte apoptosis, myofibroblast transformation, and up-regulation in the synthesis of chondroitin sulfate than PRK-treated eyes. These differences may account for better visual acuities and less stromal haze in higher attempted corrections in LASEK-treated eyes.
Esquenazi
Salomon
S
Department of Ophthalmology and Neuroscience Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA. sesque@lsuhsc.edu
He
Jiucheng
J
Bazan
Nicolas G
NG
Bazan
Haydee E P
HE
D000818:Animals; D017209:Apoptosis; D002452:Cell Count; D002809:Chondroitin Sulfates / Q000378:metabolism; D024141:Collagen Type IV / Q000378:metabolism; D003319:Corneal Stroma / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D005347:Fibroblasts / Q000473:pathology; D019084:Fluorescent Antibody Technique, Indirect; D020287:In Situ Nick-End Labeling; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer; D018903:Photorefractive Keratectomy; D011817:Rabbits; D014945:Wound Healing
D024141:Collagen Type IV; D002809:Chondroitin Sulfates