Hi,
Please do try these troubleshooting steps that may help.
- First is to do a hard reboot, remove the battery and unplug the AC adapter then press and hold the power button for 20 seconds then observe if the same problem will persist.
- Next is to connect an external monitor and observe if the same problem will happen to it as well.
- If it's normal that could mean that the problem is the built in LCD.
- I would suggest opening the laptop and check the ribbon cable that connects the LCD to the motherboard.
- If the laptop is still under the factory warranty do contact ASUS for a repair.