"It was semi-disappointing and semi-successful," said Wie, who is recovering from an injured left wrist and has failed to break 70 in more than a year.
"It's the first time I've played really solidly, but I missed some reasonably easy putts. I'm starting to see a light at the end of the tunnel now."
In perfect weather at St. Andrews, Ochoa birdied three straight holes and stretched her lead to three shots when her long approach to the 15th settled 2 feet from the pin.
That was her fifth birdie, and another followed at the 17th, the usually tough Road Hole which has been made a par 5 for the Women's Open and became the easiest to score under par.
Ochoa's second shot finished at the back of the green and her first putt left her with a 5-footer for birdie. After Miyazato bogeyed the 16th, Ochoa walked onto the 18th green four ahead of the field, then narrowly missed a 15-foot birdie on the final hole.
After winning her first title at the Evian Masters on Sunday, Natalie Gulbis didn't expect to be five behind at the turn. Without a birdie on the front nine, the American was 1 over after her bogey 5 at the second and went on for par 73, along with Paula Creamer.
U.S. Women's Open champion Cristie Kerr struggled to a 77, beginning her round with two bogeys.
"I've been putting way too much pressure on myself since the Open and it has backfired on me," she said. "I'm pushing it way too hard."
Another major winner Morgan Pressel, who won the Kraft Nabisco, had even more problems. She finished at 80, which included nine bogeys.
Defending champion Sherri Steinhauer, who is going for her fourth title in this tournament, had a 72.