Understand that I am not an expert in this particular area, but I do see people all the time with visual field loss due to strokes and tumors. In general, if there was going to be an improvement in the visual field, I would have expected it withing 3 - 6 months after the excision. If no improvement by then, chances are that it is permanant. The tumor you described was very large and I am not surprised that some visual field loss remained since there must have been tremendous pressure on the optic nerve for a long time. I'm glad, things went well otherwise.
It is likely that your husband had damage to the optic nerve due to the tumor and this damage, was irreversible, if it did not improve. It is unlikely that the damage will improve as neuronal tissue does not regenerate.
Sandy T. Feldman, M.D., M.S.
ClearView Eye and Laser Medical Center
San Diego, California