The 53-year-old O'Meara, a two-time major winner, cut short his two-week visit to Scotland to fly home to Florida and be with his family.
Bob O'Meara had heart surgery in April for an aortic aneurysm, but was taken to a hospital last week because of an infection.
"The last week has been a roller-coaster for me," O'Meara said before leaving Scotland. "I found out last Saturday that my dad was in intensive care and had been in dire straits at the weekend."
Although he knew of the illness, O'Meara played two rounds of the British Open at St. Andrews before missing the cut by one shot.
"I played the British Open last week as I know my dad would have wanted me to be at St. Andrews. We played there together 18 years ago and had a lot of fun.
"As a son who loves his father very much I am going to go back to help my sisters. It's time to go home."
