This isn't an injury or even popeye, not even close
As copperabian has suggested, the symptom and problem you are encountering at this particular moment is most likely a result of scaling over the eye. A number of Bettas are born with this, particularly dragon scales. It rarely majorly effects them in any harmful way though, maybe just a little blind or partly blind in that eye.
PS. Beautiful fish yu have there! Ive always wanted an elephant ear Betta such as the one you have, how much was it?