Sexton given all-clear
The flyhalf was withdrawn early in Leinster's 10-51 European Champions Cup loss to Wasps last weekend, but passed initial pitch-side Head Injury Assessment and is now back training after further tests.
Some pundits have suggested Sexton should retire now in the interests of his long-term well-being but Schmidt said such comments were a "disappointment".
"Johnny trained really well yesterday [Tuesday], he's fully fit and ready to go, he's passed his three," said Schmidt, speaking at the Six Nations launch in London on Wednesday.
"So that's the protocol," he added, with Ireland looking to win their third successive Six Nations title.
"It was this time last year that the problem really arose and he had the break.
"Since that time he hasn't really had too many problems.
"So as far as we're concerned and as far as Johnny's concerned he's very keen to be ready to go in 11 days' time," the New Zealander added.
Sexton was stood down for 12 weeks by French club Racing for suffering four concussions inside 12 months.
Schmidt, however, had no qualms about the 30-year-old playing on, given the quality of medical advice that the coaching staff had received.
"All we can do is go on the medical opinion, and he had two of the best guys that are around, that made some decisions for him last year and have followed up since then," said Schmidt.
"When they give him the all-clear we've got a lot of trust in them.
"I have a number of dealings with family with medical practitioners that we have huge trust in, and you know they are the experts.
"If there are people who question that, again it's always a disappointment, but also a reality.
"Because no one's going to have the same opinion necessarily, but what you try to do is get those that are best-qualified to make the decision, therefore not to put somebody at risk."
Praising Leinster for withdrawing Sexton as a precaution in the weekend's heavy defeat at Wasps, Schmidt said Ireland take head injuries extremely seriously.
"I'm always concerned," said Schmidt, when asked about concussion and its symptoms.
"We treat head injuries with the respect they need and that's why he didn't go back onto the pitch on the weekend, and I certainly respect that decision.
"It wasn't a game that was going to be significant in qualification and therefore they identified that some important games were coming up for Johnny.
"That's fallen to our advantage so he should be fully fit to go."
Ireland begin the defence of their Six Nations title at home to Wales on February 7.
Agence France-Presse
