Randy Moss asking for prayers for himself and his family ... 'cause he says he's been dealing with something internal -- and apparently it's affecting his eyes.
The NFL Hall of Famer took to his Instagram Sunday morning -- while working alongside his cohosts on "Sunday NFL Countdown" ... speaking to fans directly and telling them he's been battling some sort of health issues recently.
Moss doesn't go into detail about the exact issues ... but, he asks all the "prayer warriors" to keep him and his family in their thoughts -- so, it sounds fairly serious.