Kim K S, Lee J H, Edelhauser H F
Department of Ophthalmology, Keimyung University School of Medicine, Taegu, Korea.
J Cataract Refract Surg. 1996 Jan-Feb;22(1):44-50. doi: 10.1016/s0886-3350(96)80269-0.
To evaluate the effect of excimer laser photorefractive keratectomoy (PRK) on the corneal epithelial barrier function.
Corneal uptake of 5,6 carboxyfluorescein (CF) was measured by Bernal and Ubels' method after excimer laser PRK in New Zealand white rabbits (N = 40). One cornea in each rabbit was treated, and the fellow cornea was used as a control. In both eyes, the central 7.0 mm of the corneal epithelium was removed. Myopic PRK treatments were performed at 37.75 microns (3.3 diopters [D]) and at 52.50 microns (5.0 D). The animals were euthanized and the eyes placed in CF for 5 minutes at 3 days, and at 1, 2, and 4 weeks following PRK. The corneas were then excised and dialyzed in balanced salt solution. The CF concentration in the dialysate was measured by fluorometry. Four corneas were also prepared for transmission electron microscopy using fixative containing ruthenium red.
Three days after PRK, CF uptake increased in all study eyes compared with normal eyes (n = 5). One week after PRK, the control corneas showed a decreased CF uptake while the study corneas still had an increased CF uptake (P < .05). Two weeks after PRK, CF uptake in corneas with a 5.0 D ablation remained increased but decreased in corneas with a 3.3 D ablation (P < .05). Four weeks after PRK, CF uptake returned to normal in all corneas. The ruthenium red penetrated into the deeper layers of the corneal epithelium 1 week after PRK; only the superficial cell layer was stained 4 weeks after PRK.
Excimer laser PRK affected the corneal epithelial barrier function at 1 and 2 weeks postoperatively even though the corneal epithelium covered the ablated area. Deeper laser ablations showed higher corneal CF uptake for longer periods than shallower ablations.
评估准分子激光屈光性角膜切削术（PRK）对角膜上皮屏障功能的影响。
采用伯纳尔和乌贝尔斯的方法，在新西兰白兔（n = 40）身上进行准分子激光PRK后，测量5,6 - 羧基荧光素（CF）的角膜摄取量。每只兔子的一只角膜接受治疗，另一只角膜作为对照。在双眼的角膜中央7.0毫米处去除上皮。分别以37.75微米（3.3屈光度[D]）和52.50微米（5.0 D）进行近视PRK治疗。在PRK术后3天、1周、2周和4周时，对动物实施安乐死，并将眼睛置于CF中5分钟。然后切除角膜并在平衡盐溶液中进行透析。通过荧光法测量透析液中的CF浓度。还使用含钌红的固定剂制备了4只角膜用于透射电子显微镜检查。
与正常眼（n = 5）相比，PRK术后3天，所有研究眼的CF摄取量均增加。PRK术后1周，对照角膜的CF摄取量降低，而研究角膜的CF摄取量仍增加（P <.05）。PRK术后2周，5.0 D切削的角膜CF摄取量仍增加，但3.3 D切削的角膜CF摄取量降低（P <.05）。PRK术后4周，所有角膜的CF摄取量均恢复正常。PRK术后1周，钌红渗入角膜上皮的更深层；PRK术后4周，仅表层细胞层被染色。
准分子激光PRK术后1周和2周时，即使角膜上皮覆盖了切削区域，仍会影响角膜上皮屏障功能。较深的激光切削在较长时间内显示出比浅切削更高的角膜CF摄取量。
