None. The bulk of the problems in this case comes from the perjured med testimony and Greer's failure to check the validity of that testimony. He didn't have to use his own eyes to check, he could have asked for assistance. The condition of his sight also shouldn't effect his ability to pick up contradictory statements within the testimonies and have those contradictions removed. There's also the question of how he came to find and choose the neurologist from Ohio, that ended up perjuring himself bigtime. He's the one in the balloon video, that testified in court that Terri was unresponsive.