All Blacks centre Conrad Smith has had eye surgery to repair a detached retina and will miss at least the first two tests of the Rugby Championship.

It emerged yesterday that Smith went under the knife twice last week to repair damage to his left eye suffered in the Hurricanes' final Super Rugby match of the season against the Chiefs.

It's unclear when Smith will return to the field and although Hurricanes doctor Ian Murphy said the procedures, on Tuesday and Friday, went well, it would mean no training for the next six weeks.

That means Smith will definitely miss the All Blacks' Bledisloe Cup tests against Australia in Sydney and Auckland.

The earliest he could return would be for the September 8 test against Argentina in Wellington, but that may be a stretch after such a long time out.

Smith's absence will leave a hole in the All Blacks' midfield stocks, already affected by the pending departure of Japan-bound Sonny Bill Williams and the ongoing injury woes of Richard Kahui.

The immediate question is whether coach Steve Hansen will call in cover.

Second five-eighth is not a major issue, with Ma'a Nonu ready to return and Tamati Ellison and Dan Carter both capable in the role.

However, so strong has Smith's hold been on the No 13 jersey in recent times, there are no compelling test options in his class ready to step in.

The most obvious options are to push Nonu out a spot, or hand the role to Ellison, who did a good job off the bench against Ireland during the third test in Hamilton.

The alternative is to bring in a new midfielder.

An early hint at contingency plans could come as early as Sunday, with a 20 to 30-strong wider training squad to be named for a two-day camp in Wellington next week.

It may be a chance to look more closely at the likes of Hurricane Tim Bateman, or Crusaders Ryan Crotty and Robbie Fruean.

The availability of the Crusaders and Chiefs players for next week's camp will, of course, depend on the result of tomorrow's Super Rugby semifinal.

Hansen used 30 players against the Irish, but will name only 28 for the Rugby Championship, a squad set to be announced on August 5.

He may well feel he has enough cover in the backs, provided there are no further injuries, from those used against Ireland.

It is understood Highlanders utility Ben Smith is seen as a test option at centre, and if so Hansen may feel he has things covered.

A starting midfield of Nonu and Ellison, with Ben Smith and Aaron Cruden in the reserves, would cover all eventualities, considering Dan Carter can also shift out a position from first five-eighth.

What is certain is that Williams and lock Ali Williams will be missing from the squad that played Ireland last month.

Williams' injured knee could see a fourth lock called up to join Sam Whitelock, Brodie Retallick and Luke Romano, with Highlander Jarred Hoeata and Hurricane Jason Eaton options.

- © Fairfax NZ News