This passage is about the speaker feeling that upon losing his sight, he has lost his purpose, his talent, which it's writing and to serve God. His blindness has this effect on his talent because C)The speaker feels that without sight, he will not be able to write, study his work, or read other material. The lines that best exemplify this are the following:
And that one talent which is death to hide
Lodged with me useless, though my soul more bent