WWE issued the following :

Heath Slater was injured Saturday night when a gash developed over his right eye during a match wtih Titus O'Neil at a WWE Live Event in Bangor, Maine. The match was stopped and O'Neil was declared the winner. 

WWE ringside physician Dr. Stephen Daquino was on-site and relayed the following to WWE.com: 

"Heath has a six centimeter laceration above his right eye. It was quite open, right down to the bone. He got 18 sutures and hopefully that will close it up."

WWE wishes Slater a healthy and speedy recovery.