The Australian has not played since suffering a fractured eye socket and breaking his nose in two places against Castleford Tigers on July 8.
He had hoped to feature in the last couple of Qualifiers games but has seen his chances dashed.
Delaney, who has won three Grand Finals with Leeds since joining in 2010, explained: “I have been seeing the surgeon that operated on me and an eye specialist every week for the last eight weeks.
“They’ve come to the conclusion it is still swollen and the muscle’s not strong enough.
“I have got blurred vision at 15 degrees and that’s going to take time.
“It has cut my season short again and after being told it would be a seven-week duration initially it has turned into a nightmare.
“I can’t drive and things like that because my vision is still blurred and it has been hard the last 10 weeks.”
For a third successive campaign, he has suffered a season-ending injury after a dislocated kneecap in 2016 and hamstring issue last term.
Delaney, 32, is out of contract this autumn but is in talks with the club and hopes to stay on again.
Meanwhile, England Academy full-back Kiedan Hartley has become the second Rhinos Under-19s player to sign with Featherstone Rovers for 2019, joining team-mate Dakota Whylie at Post Office Road.
Toronto Wolfpack loose forward Jack Bussey has been banned for a total of 10 games.
He received eight matches at an independent operational rules tribunal after admitting biting Toulouse Olympique’s Bastien Ader in Saturday’s Qualifiers game.
Bussey, 26, was also handed an additional two-match ban for a grade B high tackle in the same match which he opted not to contest.
He was initially given a one-match penalty charge but, because the high tackle occurred after the biting offence, the punishment was doubled under sentencing guidelines.
Meanwhile, former Huddersfield Giants prop Sam Rapira, 31, has been forced into early retirement after injuring a hand for promotion-chasing Toulouse during that 13-12 loss against Toronto in Canada.
Rapira, a member of the Kiwis’ World Cup-winning team in 2008, was due to hang up his boots at the end of the season, his first with the French club, but has now been ruled out of the rest of the campaign.
Huddersfield’s Academy captain Jon Luke Kirby is in line for his first-team debut when they host Wigan Warriors tomorrow night.
He comes into the 19-man squad along with Alex Mellor and Oliver Russell, replacing Jordan Turner, Daniel Smith and Jake Wardle.
Elsewhere, Hull KR winger Justin Carney will return as coach/captain of his former “bush footy” team Nyngan Tigers in New South Wales in 2019.