Hi,
First you need to be sure that there are no cracks on the display. That kind of line pattern are a typicall symptom of accidental damage, check for small cracks near the lowest edges of the screen.
If the screen is OK connect the MBP to an external display to see if the line pattern replicates also there, if the image shown in the external display has no lines then you have an issue with the Display (most probable) or the Main Logic Board (less probable).
You need to take the MacBook directly to Apple or an AASP for the repair, they need to run specific post-repair test to calibrate the new display and LAS (Lid Angle Sensor).