The four-time Hawthorn premiership player, who ended his career at Melbourne, was knocked out by Western Bulldogs opponent Jarrod Harbrow in a sickening collision.
But Lewis returned to the field for the Hawks in the same 2010 match.
The following year, the AFL banned players from going back on the ground in the same game if they had been forced off because of concussion.
According to a media report on the weekend, there had been an international warning in 2001, saying a player with signs of concussion should not be able to return to a game or training session on the same day.
A class action by former AFL players over concussion-related injuries is set for trial next year.
"I went back on the ground (after his concussion), but I think after reading that article, and I think the disappointing thing for me was to understand that there was information out there that had been backed by the top head trauma guys in the world, and the AFL had been provided that information, yet still didn't act," Lewis told Fox Footy.
"And it was 10 years later that that had happened, so I think the AFL set the guidelines for players to enter the competition, and,I take responsibility for the concussion.
"But I think what happened after that could have been certainly held or done better by the AFL with the information that they had been given.
"I'm just disappointed that the AFL had information and didn't act on it from the experts that are in this field, and I think a lot of players would feel the same way."
Former Richmond premiership star Jack Riewoldt said there was "a grey area" in the timeline of the AFL's handling of the concussion issue.
"It's certainly a worrying thing that we've got to this, and information has been withheld from a playing group," Riewoldt said.
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