A source close to Jason tells TMZ that the actor went under the knife Saturday at a Los Angeles hospital (the first of several surgeries to come) to repair a deep nasal fracture, a severe orbital floor fracture and have a titanium plate inserted into the right side of his face. 

We're told Jason feels as bad as he looks -- he's in a severe amount of pain following the surgery, but is trying to keep his spirits up. 

Jason isn't out of the woods yet. We're told he still has orthopedic and eye surgeries left to go and it will be a "very long time" before he is functional. 
 

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