- A restricted field of vision as the result of looking through some type of object or a medical condition.
It took some time for him to get used to the tunnel vision he experienced while looking through a periscope.
- (figuratively) The tendency to focus one's attention on one specific idea or viewpoint, to the exclusion of everything else; a one-track mind.
After Mark fell victim to tunnel vision, nothing you could say to him would change his mind.
restricted field of vision
one-track mind — see one-track mind