Even though the reader can only surmise what an author's intentions are in writing passages, however, there is reason to believe that Harper Lee in Chapter Ten of To Kill a Mockingbird wished to illustrate just how good a shot Atticus Finch is that he can aim and shoot with his right eye even without glasses and without having shot a gun in years. Without having his glasses to help him aim and shoot, Atticus really impresses the children; in fact, Jem is speechless in his effort to praise his father and express his new-found admiration that his father can, afterall, "do something." Meanwhile, Miss Maudie makes the pertinent remark, "I saw that, One-Shot Finch!" and underscores the point she has made to the children previously.
This to me shows how Atticus' glasses show his age. Once he took off the glasses he became young again in a way and he became one shot finch again.