tunnel vision
noun [ U ] uk/ˌtʌn.əl ˈvɪʒ.ən/ us/ˌtʌn.əl ˈvɪʒ.ən/
(SEEING)
管状视，视野狭隘（一种眼疾）
a medical condition that makes someone see only things that are directly in front of them
(THINKING)
disapproving井蛙之见，一孔之见
the fact that someone considers only one part of a problem or situation, or holds a single opinion rather than having a more general understanding