Charlton skipper Christain Dailly will be sidelined for up to a month with a fractured eye socket.
The veteran defender had surgery on Wednesday after suffering the injury against Dagenham in the Johnstone's Paint Trophy last week.
"Christian will be sidelined for around three to four weeks," said manager Parkinson.
"He had an operation on Wednesday and it was pretty straightforward. We're disappointed to lose him but we move on.
"The op went very well - there were no problems at all. He's got to rest until next Thursday and then he can join in training.
"I suppose the advantage of this type of injury is that we can keep him going physically while he recovers, but we'll obviously have to be careful when it comes to heading the ball. It won't be long until Chris returns and when he does get back in training he'll be almost ready to play."