Off-screen, Bette Davis suffered a nervous breakdown during filming as a result of her crumbling marriage to Harmon Nelson. Reportedly, producer Hal B. Wallis convinced Davis that she could benefit by using these real-life emotions of pain and loss to enhance the portrayal of her character. Meanwhile, Davis's marital problems didn't prevent her from embarking on an affair with co-star George Brent. Davis and Brent appeared in a total of 11 movies together.
During the filming of the emotionally-charged scene when Bette Davis's character needs to find her way upstairs to her room after the brain tumor has caused her blindness, the cast and crew and several visitors were watching as she grasped the banister and began to feel her way up the steps, one by one. Halfway to the top of the staircase Davis paused, stopped the scene, briskly walked back downstairs and addressed director Edmund Goulding. "Ed," Davis said, "is Max Steiner going to be composing the music score to this picture?" Goulding, surprised by the question, replied that he didn't know, and asked Davis why the matter was important enough to stop the filming of the scene. "Well, either I'm going to climb those stairs or Max Steiner is going to climb those stairs," Davis responded, "but I'll be God-DAMNED if Max Steiner and I are going to climb those stairs together!"
The scene in Dr. Steele's office where Judith can't light her cigarette, and then a few minutes later she can't light Dr. Steele's, was devised by Edmund Goulding. He explained it as, "When Bette Davis can't light her own cigarette, you know something is seriously wrong with her."
Bette Davis pestered Warner Brothers to buy the rights to the story, thinking it a great vehicle for her. WB studio chief Jack L. Warner fought against it, arguing that no one wanted to see someone go blind. Surprisingly, the film went on to become one of the studio's biggest successes of that year.