THE AFL's skinniest ground will get even tighter as the League moves to reduce boundary sizes at GMHBA Stadium.

Ahead of Geelong's final four matches at the venue this year, the wings will each be brought in by half a metre, the ground's width narrowing to 116m.

It will ensure a 5.5 metre gap between the boundary line and fence, putting it above the AFL's minimum requirement of five metres.

Goal posts will remain in the same spot with the ground's length to stay at 170m.

It is believed that the reduction in playing surface was implemented for the NAB AFL U18 championships matches played at the venue last Friday.

The move comes after North Melbourne skipper Jack Ziebell had a brush with the abrasive LED signage in his side's round 12 loss – the most recent match at GMHBA Stadium this season.

Ziebell was forced to spend eight minutes off the ground in the tight contest as he received attention on cuts to both knees.

The AFL will continue to work through a national strategy to consider signage changes at all venues this week after a number of separate incidents this year.

Geelong defenders Zach Tuohy and Mark Blicavs required stitches after they both ran into Perth's Optus Stadium fence in round three.

As a result, a decision was made to place protective covering over the new venue's signage.

Superstar Patrick Dangerfield also had an awkward run-in with the fence at Etihad Stadium in Geelong's loss to the Western Bulldogs on Friday night and cut his knee.

Patrick Dangerfield appeared to cut his knee on the LED signage around Etihad Stadium.#AFLDogsCats pic.twitter.com/UreXgQCCRy — AFL.com.au (@AFLcomau) June 29, 2018

The Cats next host Melbourne at GMHBA Stadium in round 18 before playing Brisbane, Fremantle and Gold Coast at home in the run home.