家兔PRK术后角膜超微结构的实验研究

THE STUDY OF ULTRASTRUCTURE IN WOUND HEALING OF THE RABBIT CORNEA AFTER EXCIMER LASER PHOTOREFRACTIVE KERATECTOMY

目的 评价实验性家兔不同屈光度 Ｐ Ｒ Ｋ 术后角膜创面愈合的过程。方法 应用 Ｓ Ｖ Ｓ Ａ Ｐ Ｅ Ｘ Ｐ Ｌ Ｕ Ｓ 型准分子激光治疗系统对６ 只家兔双眼进行 Ｐ Ｒ Ｋ 术。结果 透射电镜观察：术后３ ｄ ，角膜上皮细胞１ 层或２ 层覆盖切削区，角膜前基质胶原纤维排列紊乱。术后３０ｄ ，可见角膜上皮细胞增生，体积增大，细胞由正常的５ 层或６ 层增加到７ 层或８ 层；上皮细胞间可见桥粒连接，基底膜形成，但有不连续现象；上皮基底细胞于基底膜之间可见半桥粒。术后１００ｄ ，角膜上皮细胞基本恢复正常。扫描电镜观察：术后１００ｄ ， 上皮细胞界限分明， 上皮明亮细胞较多，但微绒毛、微皱褶相对减少。结论 Ｐ Ｒ Ｋ 术后１００ｄ 角膜组织结构基本正常，但仍有组织薄弱处和特殊性改变。 Ｐ Ｒ Ｋ 术后家兔角膜上皮微绒毛、微皱褶相对减少，可能是临床上 Ｐ Ｒ Ｋ 术后部分患者近期角膜干燥的原因之一。

Objective To evaluate the corneal healing of non-equality diopter response ultrastructure after excimer laser photorefractive keratectomy (PRK) with SVS APEX PLUS excimer laser. Methods PRK wax performed on both eyes of 6 white rabbits (12eyes).Results TEM demonstration 3 days after the operation,one or two layers of corneal epithelial cells covered the ablation zone.Beneat the ablation zone, the corneal collagen fibers appeared in abnormal alignment and did not show any damage.30 days after PRK, the epithelial cells showed hyperplastic changes. The cells were larger and increased to 7 or 8 layers of cells from the normal 5 or 6 layers. The superficial stroma showed irregular lamellar structure.The profundal stromata showed regular lamellar structure. 100 days sfter PRK, the corneal epithelium returned to normal again.SEM demonstration 100 days after PRK, epichelium was clear with more bright epithlium.Microplicae and mcrovilli were less than before.Conclusion Despite recovery of a continuous and smooth epithelial layer and near normal corneal tissues 100 days after PRK, abnormalities of both epithelium and superficial stroma could be detected in the area of ablation. The microplicae and microvilli of rabbit cornea epithelium became less after PRK, which can be one of reasons which cause ocular dry sensation in the same patienes.