How did the visit to Baltimore change Helen's life in a great way?

As Helen grew from toddlerhood to school age, she became increasingly frustrated at her inability to communicate her thoughts to other people. This led to frequent tantrums and meltdowns, so much so that her parents became concerned and took her to see an eye specialist in Baltimore named Dr. Chisholm in the hopes he could help her regain some eyesight. He could not, but referred the family to Alexander Graham Bell. Helen remembered visiting Bell in Washington and playing with his watch. She recalled his kindness.
Bell, in turn, referred the family to the Perkins Institute in Boston, where they were able to hire Miss Sullivan as a teacher for Helen. Helen describes Miss Sullivan's arrival in her memoir as a life-changing miracle, because, through Miss Sullivan, she learned to communicate through manual writing. Keller also maintained a long lasting friendship with Dr. Bell.

Helen's parents thought a trip to Baltimore to see a prominent oculist would be the answer to their daughter's problems. After examining Helen's eyes, Dr. Chisholm delivered disappointing news: he could not help her eyesight. He did, however, give them information that would start a chain of events. This chain of events led Mr. and Mrs. Keller to hire Miss Annie Sullivan, the woman who became Helen's teacher.
Dr. Chisholm told Mr. and Mrs. Keller that Helen "could be educated, and advised [her] father to consult Dr. Alexander Graham Bell, of Washington, who would be able to give him information about schools and teachers of deaf or blind children" (Chapter III). They visited Dr. Bell, and he referred them to Mr. Anagnos of the Perkins Institution. This was a school for the blind located in Boston. They wrote to Mr. Anagnos, and he found Miss Sullivan to be Helen's teacher. Miss Sullivan taught Helen how to communicate, which changed her life. She remained Helen's teacher and companion for decades.