Rumors in my office abound that neckties are bad for your health. One manager often scoffs that "they even did studies" and that ties impair blood flow.
Checking Wikipedia offers a few hints but the relevant parts undersourced:
[V]ascular constriction occurs with over-tight collars. Studies have shown increased intraocular pressure in such cases, which can aggravate the condition of people with weakened retinas. There may be additional risks for people with glaucoma. Sensible precautions can mitigate the risk. Paramedics performing life support remove an injured man's necktie as a first step to ensure it does not block his airway.
 appears to be a study specifically focused on the "effect of a tight necktie on intraocular pressure".
Aside from intraocular pressure issues, do neckties pose any health threat with regards to blood flow?