准分子激光角膜切削治疗高度近视的神经损伤与再生

①目的 观察准分子激光屈光性角膜切削术（ＰＲＫ）治疗高度近视角膜神经损伤与再生的形态学变化，探讨角膜知觉减退与恢复的形态学基础及其与角膜雾状混浊的关系。②方法 ２４只白兔左眼均按－１５．００Ｄ行ＰＰＫ治疗。右眼作为对照，于术后第１，３，１０，３０，９０，１８０天取角膜标本，光镜、电镜下观察角膜神经的损伤与再生情况。③结果 术后１～３ｄ，切削区内深层神经干断端未见再生。术后第１０天，光镜下见上皮层神

AN EXPERIMENTAL STUDY ON CORNEAL NERVE DAMAGE AND REGENERATION AFTER EXCIMER LASER PHOTOREFRACTIVE KERATECTOMY FOR HIGH MYOPIA

Objective To observe the morphological changes and ultrastructural organization of corneal nerve damage and regeneration after excimer laser photorefractive keratectomy (PRK) for high myopia, and evaluate the morphological basis for the changes in corneal sensitivity and the correlation with haze. Methods 24 white rabbits were used.A one pass three zone technique was used to correct high myopia (-15.00D) in left eyes, and right eyes were used as control.Light micrography (acetylcholinesterase staining) and electron micrography were used to demonstrate morphological features in rabbit corneal nerves at 1 day, 3 days, 10 days,30 days,90 days and 180 days after PRK. Results At 1 or 3 days after PRK, the subepithelial nerve plexus and stromal nerve trunks didn't regenerete in high myopia group. At 10 days, some regenerating nerves within the treated area in epithelial and subepithelial layers were visualized in high myopia group.30 days after PRK the density of regenerative fibrils in epithelial layer in high myopia group was higher than that of normal and peaked at 90 days after PRK. In high myopia group 30 days after PRK, new regenerating stromal nerves sprouting was detected. Nerve regeneration had not completed in the central cornea in high myopia group at 180 days after PRK. Electron micrography showed abnormal ultrastructure of corneal nerves at 30,90 and 180 days after PRK, such as decrease of neurofilaments and swollen mitochondria. Conclusion PRK for high myopia can excise stromal nerve trunks. Stromal nerve regeneration is slower and ultrastructure of nerves is abnormal. The recovery of corneal sensitivity needs a long term. Haze in high myopia group after PRK being more intense may be related to the damage of corneal stromal nerve trunks. [