The actress Selma Blair appeared at the Vanity Fair Oscar party on Sunday evening wearing a diaphanous Ralph & Russo gown and carrying a custom-made cane covered in black patent leather.

It was her first public event since she announced in October her diagnosis of multiple sclerosis, a chronic and often disabling disease affecting the central nervous system.

In an interview that aired on ABC’s “Good Morning America” on Tuesday, Ms. Blair, 46, spoke to the news anchor Robin Roberts about what it was like to live with the disease, which has affected her speech and made it difficult for her to walk unassisted.

Ms. Blair, who has appeared in movies including “Cruel Intentions,” “Legally Blonde” and “Hellboy,” said she had been experiencing symptoms at least since her son was born in 2011. She said she did her best to handle the intense fatigue, emotional distress and loss of physical control. But the disease was not formally diagnosed until August.