Hdmi - refresher rate???? vs. refresher rate of regular tv.

since my friend/or x installed hdmi on his sony tv of 5 years - my eyes have been burning/in full pain.
he refuses to hear me. nor have a professional check it out. and refuses to deal with the contrast or any levels. he's spanish and likes it and nothing else matters to him
can somebody please explain to me why this is happening to my eyes. he also had a new lamp put in it a couple days ago. is there culpritness to that too? before the new lamp and the hdmi i was 100% great to watch.
i'm ignorant with this so please be patient with me and ask me questions. thanks