When he sees it, it makes his 'blood run cold', this implies to the reader that he is insane as he is afraid of an eye.
After review of both Poe's short-story, The Fall of the House of Usher, and the video production of its similar screenplay, it wouldn't take a genius to determine the obvious differences.
In fact, it certainly doesn't take a genius to make a difference comparison as I have made the following observations.
In the matter of Rodderick Usher, however, I can't give as much praise to the 1980s chains-rattling-for-sound-effects work.
To Master Usher's sanity, it would have, again in my opinion, been better to leave him under the conviction of certain superstition and madness as written by Poe.