Sydney vice-captain Luke Parker has put the acid on the Swans' midfield to lift out of its slump against Geelong as the club's big man stocks took another hit on Thursday.

Already without superstar Lance Franklin, key forward Sam Reid and ruckmen Sam Naismith and Kurt Tippett, the Swans have lost the versatile Dean Towers to a freak injury at training.

Freak injury: Sydney's Dean Towers will miss the clash with Geelong after being poked in the eye Credit:AAP

Towers, who had been relieving Callum Sinclair in the ruck, copped a poke in the eye, forcing the Swans to make three changes for the trip down to Geelong.

"Whilst he's feeling ok the bleeding in the eye means if he was to play this week it could put his eye at risk," Swans coach John Longmire said . "Clearly we don't want to do that. It's not even the conservative approach, it's the proper approach."