The keratocyte proliferation and the using of corticosteroids afterexcimer laser photorefractive keratectomy
Zhu Lina, Chen Ti, Liao Rongfeng (Dept of Ophthalmology, The 1st Affiliated Hospital of Anhui Medical Universit y, Hefei 230022)
Objective To observe the status of keratocyte proliferation after excimer laser photorefractive keratectomy and the validity of clinical therapy by using corticosteroids. Methods Using KERATOM F, an argon fluoride large optic zone laser system(193 nm),the rabbit cornea were ablated at a depth of 94 μm and diameter of 6 mm of optic zone.18 rabbit from 24 were ablated by excimer laser, and the others were negative matched controls.For each rabbit of the 18 cases, c orticosteroid and antibiotics eye drops were used to one eye and single antibiotics to the other.The corticosteroid eyes were treated by corticosteroid eye drops trice every day in the first month, twice in the second month and once in the third month. We followed them up to 2 months with a slit lamp postoperatively, recorded the haze degree, sacrificed 6 rabbits randomly at 4th days,in first month and seco nd month respectively. 1/2 of the cornea samples were investigated histoligically and immunohistochemically. The other 1/2 were studied structurally by electron microscope. TGF beta 1 and PCNA were detected in corneal epithelial and stromal cells. Results Corneal healing were delayed but haze were slight and vanished earlier in those treated with corticosteroid eye drops than those used simple antibiotic eye drops ( P 0 05). TGF beta 1 and PCNA expression in cornea were both observed in the corticosteroid and single antibiotic eyes. I n the 4th day, TGF beta 1 and PCNA expression were higher than the nagative control group( P 0 05). But these two factors overexpressed in the single antibiotic samples in the first month while lower in the corticosteroid group. In second mont h, expression level of TGF beta 1 and PCNA of corticosteroid group was similar to negative control group.Conclusion There are proliferations in the corneal keratocytes after excimer laser photorefractive keratectomy. Treatment of corticosteroid after excimer laser photorefractive keratecto my is effective in decreasing proliferation of keratocytes and inhibiting haze for ming.