准分子激光角膜切削术后角膜细胞的增生及激素的治疗作用

The keratocyte proliferation and the using of corticosteroids afterexcimer laser photorefractive keratectomy

目的 探讨PRK激光角膜切削术后 (PRK)角膜细胞的增生情况及皮质类固醇的治疗作用。方法 通过对准分子后角膜上皮及基质细胞的转化生长因子 β1 (TGF β1 )和增生细胞核抗原 (PCNA)的免疫组化观察 ,在 2 4只日本大白兔中设立对照 6只 ,其余 1 8只应用轰炸式准分子激光行光学角膜切除术 ,术后每只兔一眼用单纯抗生素治疗 ,另一眼用抗生素加皮质类固醇激素治疗 ,皮质类固醇眼药水按每日3、2、1次逐月递减。术后用裂隙灯显微镜观察眼前段情况 ,检查角膜上皮下混浊的形成情况并按照Rai的分级标准进行记录。分别于 4天、1个月及 2个月随机处死 3只兔取角膜 ,1 /2用于普通光镜及免疫组化染色 ,另 1 /2用于透射电镜观察。用免疫组化方法观察TGF β1、PCNA在兔角膜上皮细胞及基质细胞中的表达状况。结果 应用抗生素加皮质类固醇治疗的兔眼 ,角膜上皮愈合较单纯抗生素组延迟(P <0 0 1 ) ;但角膜上皮下混浊 (Haze)的程度较轻且消失快(P <0 0 5)。免疫组化结果表明 :术后第 4天 ,行PRK手术治疗的兔眼虽然仅有单层角膜上皮细胞覆盖 ,角膜上皮细胞及基质细胞TGFβ1和PCNA的表达水平均较对照组高 (P<0 0 5) ;至 1月时 ,行PRK治疗的两组上皮细胞层数增多且TGFβ1和PCNA的表达水平仍高 ,激素应用组略有下降 ;术后

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.