“Lodged with me useless” means that his talent as a poet is useless now that he is losing his sight. “Though my soul more bent/ to serve therewith my Maker” can be roughly paraphrased, “although my soul is even more inclined to serve God with that talent.” This is especially frustrating to want to serve God with his writing but to feel his talent will be wasted as he becomes blind. He wishes ultimately to “present his true account,” or give a good account of himself and his service to God.