Callam was hurt during the 27-3 defeat by South Africa

The Edinburgh star suffered blurred vision in last Saturday's 27-3 defeat by the Sprinboks at Murrayfield.

Team doctor James Robson said: "He has an unusual and complex injury to his face which is requiring us to take advice from several medical sources.

"We hope in the next 24 hours to confirm the extent of his injury."

Prop Gavin Kerr and flanker Kelly Brown also picked up knocks at Murrayfield.

Scotland begin their World Cup campaign with a Pool C match against Portugal in St Etienne on Sunday, 9 September.

Despite Callam's injury, head coach Frank Hadden believed his gamble of playing just two World Cup warm-up games has paid off.

"We didn't pick up too many injuries and can take a massive amount from the game," he told BBC Sport after the Murrayfield clash.

"South Africa have played 10 games in the build up, so they are a lot match sharper than we are.