Mietz H, Prager T C, Schweitzer C, Patrinely J, Valenzuela J R, Font R L
Department of Ophthalmology, Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA.
Br J Ophthalmol. 1997 Jul;81(7):584-9. doi: 10.1136/bjo.81.7.584.
To prevent scarring after surgical optic nerve sheath decompression, it has been suggested that treating the area of fenestration with mitomycin C (MMC) might be effective. An animal model was used to test whether this toxic substance may cause optic neuropathy.
The optic nerves of 15 rabbits were exposed to balanced salt solution (BSS) or mitomycin C (MMC) in a concentration of 0.2 or 0.5 mg/ml. The unoperated fellow eyes and the eyes that received BSS served as controls. Steady state visual evoked potentials (VEPs) at 40, 50, and 60 Hz were recorded before and 4 weeks after surgery. The nerves were examined by light and electron microscopy after 5 weeks.
VEPs in all non-operated eyes and eyes treated with BSS before and 4 weeks after surgery demonstrated responses at all three stimulus frequencies tested. Eyes operated with MMC had extinguished responses for one, two, or all the different temporal frequencies after 4 weeks with marked reduction in VEP amplitude. Eyes operated with MMC at a concentration of 0.5 mg/ml had significantly more reduced VEP responses than those where MMC 0.2 mg/ml was used. On histopathological examination, special stains for myelin and axons showed normal axons and myelin. On electron microscopy, no distinct abnormalities were seen among nerves operated with MMC and controls.
The data from this study suggest that in rabbits, the application of MMC to the optic nerve has a dose dependent toxic effect in the short term postsurgical follow up period. While a functional alteration could be demonstrated reproducibly by steady state VEPs, the extent was not obvious on histopathological examination of the nerves.
为预防视神经鞘膜减压术后瘢痕形成，有人提出用丝裂霉素C（MMC）处理开窗区域可能有效。本研究使用动物模型来测试这种有毒物质是否会导致视神经病变。
15只兔子的视神经暴露于平衡盐溶液（BSS）或浓度为0.2或0.5mg/ml的丝裂霉素C（MMC）中。未手术的对侧眼和接受BSS处理的眼作为对照。在手术前和术后4周记录40、50和60Hz的稳态视觉诱发电位（VEP）。术后5周通过光镜和电镜检查神经。
所有未手术眼和术前及术后4周接受BSS处理的眼在所有三个测试刺激频率下均表现出反应。接受MMC手术的眼在4周后对一种、两种或所有不同时间频率的反应消失，VEP振幅明显降低。使用浓度为0.5mg/ml的MMC进行手术的眼，其VEP反应比使用0.2mg/ml的MMC的眼明显降低。组织病理学检查显示，髓鞘和轴突的特殊染色显示轴突和髓鞘正常。电镜检查显示，接受MMC手术的神经与对照神经之间未见明显异常。
本研究数据表明，在兔子中，在术后短期随访期内，将MMC应用于视神经具有剂量依赖性毒性作用。虽然稳态VEP可重复性地证明功能改变，但在神经组织病理学检查中程度并不明显。
