Q. If someone reads the megilla for an elderly person who may not be able to concentrate for the complete reading, should he ask the elder to read with him from the megilla?
A. Horav Shlomo Miller's Shlit'a opinion is that it is not recommended for the elder to read aloud as he may make mistakes, besides he is also not listening then to the voice of the reader, but rather concentrating in his own mistaken reading. It is better to tell him to read with his eyes and listen well to the voice of the reader.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit'a