Schwartz D M, Duncan K G, Duncan J L
Department of Ophthalmology, University of California, San Francisco 94143-0730, USA.
Cornea. 1998 Mar;17(2):196-9. doi: 10.1097/00003226-199803000-00014.
To determine the duration of anesthesia, effect on corneal reepithelialization, and systemic toxicity of topical tetrodotoxin (TTX) administered after excimer laser keratectomy.
Two groups of six rabbits each underwent excimer laser keratectomy in the right eye to create a 5-mm-diameter wound, 75 mm in depth. One group then received a 40-microl aliquot of topical 1 mM TTX into the injured eye, whereas the other group received 40 microl of the sodium citrate vehicle as a control. The rabbits were treated with TTX or vehicle again at 6, 12, 18, and 24 h. Corneal sensation was tested at 3, 6, 9, 12, 15, 18, 21, 24, 30, 32, and 40 h. To determine whether TTX inhibited corneal reepithelialization, compared with vehicle-treated control eyes, the healing rate of the epithelial defect was measured.
Administration of TTX every 6 h for 24 h produced nearly complete anesthesia for > or = 30 h. At 32 h, 8 h after the final application of TTX, there was still significant anesthesia of the TTX-treated corneas (p = 0.0325, Wilcoxon test). Normal corneal sensation in all TTX-treated animals returned at 40 h, or 16 h after the final dose. In contrast, vehicle-treated eyes all had normal sensation for nearly the entire duration of the experiment. At 40 h, the TTX-treated eyes had slightly larger defects than vehicle-treated eyes, 7.85+/-1.74 versus 4.54+/-1.31 mm2 (p < 0.025, t test). However, at 49 h and thereafter, both groups were equally healed (p > 0.05, t test). No systemic toxicity was observed in any of the rabbits.
Topical TTX is a long-acting and nontoxic local anesthetic in a rabbit model of excimer laser keratectomy.
确定准分子激光角膜切削术后局部应用河豚毒素（TTX）的麻醉持续时间、对角膜再上皮化的影响及全身毒性。
两组，每组6只兔，右眼行准分子激光角膜切削术，制作直径5mm、深75mm的创口。一组随后向伤眼局部滴入40微升1mM的TTX，另一组滴入40微升柠檬酸钠赋形剂作为对照。在6、12、18和24小时再次用TTX或赋形剂处理兔。在3、6、9、12、15、18、21、24、30、32和40小时测试角膜感觉。为确定TTX是否抑制角膜再上皮化，与赋形剂处理的对照眼相比，测量上皮缺损的愈合率。
每6小时给予TTX共24小时产生近30小时或更长时间的几乎完全麻醉。在32小时，即最后一次应用TTX后8小时，TTX处理的角膜仍有明显麻醉（p = 0.0325，Wilcoxon检验）。所有接受TTX处理的动物角膜感觉在40小时或最后一剂后16小时恢复正常。相比之下，赋形剂处理的眼在几乎整个实验期间感觉均正常。在40小时，TTX处理的眼缺损略大于赋形剂处理的眼，分别为7.85±1.74与4.54±1.31平方毫米（p < 0.025，t检验）。然而，在49小时及之后，两组愈合情况相同（p > ０.０５，t检验）。未在任何兔中观察到全身毒性。
在准分子激光角膜切削术兔模型中，局部应用TTX是一种长效且无毒的局部麻醉剂。
