Players screens are glitching when they move

It's very hard to explain, so keep that in mind.
When a player moves (only at my spawn world it does this) there screen totally glitches back and forth,
If they tp somewhere else in the same world it glitches even more back and forth. Its like 2 images moving back and forth. Has anyone else gotten this error or what ever it is.
Could there be something wrong with the world?
Plz help.
-BlockTheEnd