The 33-year-old jockey was airlifted to hospital after being dislodged when her horse veered sideways 150m after winning heat 11 at the trials meeting and it is believed a rival horse following her contacted her head straight after the fall.
Paramedics were on the scene to treat Myers who was believed to have been knocked out in the incident.
"Rosie has just been moved to the ICU," her husband William Fell told the Herald form Wellington Hospital last night.
"She has been in the induced coma since before she was flown here and hasn't been brought out of that.
"So we have been told to wait to see what happens in the next 12-24 hours but at this stage she doesn't need an operation."
The accident was extremely unusual in that it happened after the trial had been run and the horses were slowing down to turn around and return to the stables.
Myers's mount ducked sideways, she was dislodged and the horse following her struck her.
Trials are conducted under race-like conditions to educate horses or improve their fitness and the Racing Integrity Unit steward in charge of the meeting Neil Goodwin said the incident was minor in how it unfolded but Myers was simply unlucky.
The winner of 650 races in New Zealand alone, Myers is a respected senior member of the jockey's ranks.