Let us remember that as the play opens we are introduced to a family that has tried every possible contact to look for somebody who can help Helen with her condition and also assist them in supporting Helen. Now, it is clear from this opening scene that Keller has reached a point where he has had too many disappointments, and has decided that it is wiser to accept what he thinks is the inevitable, and that Helen can never be helped. This of course brings him into conflict with Kate and Aunt Ev, who still maintain hope that somebody could be found who could help Helen. Thus when they talk of a famous oculist in Baltimore, and Aunt Ev asks Keller why he doesn't write to him, note how Keller responds:
I've stopped believing in wonders... The child's been to specialists all over Alabama and Tennessee, if I thought it would do good I'd have her to every fool doctor in the country.
Then, after this, he says to his wife a very revealing comment:
Katie. How many times can you let them break your heart?
Keller, it is clear, has reached the limit of what he can cope with in terms of having yet another false hope that is doomed to be crushed. Thus the context of the opening scene refers to writing to another specialist who they hope can help Helen.