outer sheath of optic nerve

例句：

1. 1. Theouter sheath of the optic nerveis crucial for vision.
   视神经外鞘对视力至关重要。
2. 2. In some cases, damageto the outer sheath of theoptic nerve can lead to blindness.
   在某些情况下，视神经外鞘的损伤可能导致失明。
3. 3. Researchers are studying theinner and outer sheaths of theoptic nerve to better understand its function.
   研究人员正在研究视神经内、外鞘以更好地了解其功能。