Can tight ends wear visors?
Under NFL rules, any player may wear a visor as long as it's
untinted. Special approval (and usually a doctor's prescription) is
required for tinted visors.
NCAA (college) and NFHS (high school) rules go a little further
in that they also specify that the visor must be "rigid" (and, as
far as I can tell, there's no provision whatsoever made for tinted
visors; the visor must be clear and untinted). However, they don't
place any restrictions on which positions are allowed to wear
them.