Warren Gatland says Stuart Hogg was told he could have potentially lost his sight if he had played for the British & Irish Lions again on the current tour.
It was confirmed on Tuesday morning that the Scottish full-back would miss the remainder of the tour of New Zealand due to a facial fracture sustained in last weekend's match against the Crusaders.
Hogg was caught in the face by team-mate Connor Murray's elbow as he chased his own kick in the 12-3 victory in Christchurch last Saturday.
After receiving medical advice from several sources, Gatland made the decision to send Hogg home.
"He's absolutely gutted," Gatland told Sky Sports News HQ. "He saw about four different specialists and one said he could be okay in seven to 10 days and the others said there was a possibility he'd lose his sight if he played.
"It was just a freak accident. We told him it was only a game of rugby and that his health is more important and he understood that."
Gatland says it is unlikely the Lions will call up a replacement for Hogg with players such as Anthony Watson, Leigh Halfpenny, Jared Payne, Liam Williams and Elliot Daly all capable of filling in at full-back.
"We'll see what happens tonight but we think we've got enough cover at full-back," he said. "We'll see how we get through tonight's game but we're good enough in that area at the moment."