Van der Vaart hobbled off during Spurs' 5-1 defeat to Manchester City just over two weeks ago amid fears he had torn the hamstring in his left leg.
Tottenham later confirmed the injury and said they expected the Dutchman to be out for six weeks.
Because of this, and his decision to give priority to Spurs' domestic campaign, Redknapp decided to omit the 28-year-old from his squad for the Europa League group stages.
However, after seeing specialist Dick van Toorn in his homeland, Van der Vaart is confident that he will be back in action much sooner than expected, and could possibly even play in this Sunday's Barclays Premier League match against Liverpool at White Hart Lane.
But Redknapp told Sky Sports News: "The first diagnosis on Rafa's hamstring was that he would be out for six weeks - at least," the Spurs boss told Sky Sports News.
"Six weeks down the line, he misses the first four games, and we only have six games, so we thought there was not much point putting him in. We might as well put in some of the other lads who can play.
"The game he would have come back for would have been the game out in Russia and it would have been a long journey for him.
"We thought we'd leave him out and if we get through the group he can come in then.
"I wouldn't have slapped Rafa out on that long journey probably anyway. He's a very important player for us.
"He was away in Holland having treatment. I would have sent him a carrier pigeon with a message, but I didn't feel it was that important."
Van der Vaart earlier wrote on his personal website: "I still think it's a peculiar situation.
"Spurs could at least have consulted me. Anyway it's up to the point of no return. I will be focusing on the game against Liverpool.
"I'm pretty convinced I will be fit by then thanks to Dick van Toorn."
Spurs kick off their Europa League campaign against PAOK Salonika in Greece on Thursday. If they get through the group stages, they will be allowed to add three new names to their squad.
Redknapp intends to blood a number of youngsters such as Harry Kane, Tom Carroll and Jake Livermore to help his team's push for a Champions League spot from the Premier League.
Redknapp's team, who won their first points of the season with a 2-0 win at Wolves on Saturday, are facing a mounting injury crisis.
Michael Dawson is the latest to suffer an injury. The England defender picked up an Achilles problem and faces two months on the sidelines.