The 23-year-old, who joined the Storm from the Warriors this season, copped an accidental knock to his eye playing against Cronulla in round 15 in early June.
Initially thought to be a scratch on his eyeball, the injury worsened and Katoa required retinal surgery followed by a strict recovery process.
"They initially thought it would probably settle down in a week but it got worse and I had to have surgery. It took six weeks (to recover)," the former Warriors prodigy said.
"There was a little tear on the top of my retina and they had to put a gas bubble in my eye.
"I had to use a massage table and lay face down for a week which wasn't fun at all.
"I couldn't do anything. I couldn't leave my room, I had to lay down on the table and even sleep like that."
Katoa said it was like starting his season from scratch when he returned to training three weeks ago.
The Tonga-born ace made his return to the NRL last round against Parramatta, picking up a try among the eight scored by the Storm in a 46-16 demolition job.
Melbourne have struggled for consistency this season and need to back up that strong performance when they take on the ladder-leading Panthers on Friday night in Penrith.
The teams squared off three games ago at Melbourne's Marvel Stadium, with the Panthers running out comfortable 34-16 victors. Katoa missed that match due to his injury.
Katoa, who recently re-committed to the Storm on a three-year deal, never played in a final during his three seasons with the Warriors.
"I'm excited about the challenge as I didn't play (Penrith) last time," he said, with Melbourne fourth on the table.
"They're a quality side and they're on the top of the table for a reason, so it's going to be a tough challenge but the boys are looking forward to it.
"We're four or five weeks away from the finals. We had a good game last week but we need to back it up."
