What is the rule regarding tinted eye shield under Canadian Football rules?

If they are not allowed, was there ever a time when they were allowed?

Thank you my brothers from the north!

Canadian Ruling
 

Up until the last rule changes they were allowed no questions asked.

Now in order for them to be legal, there must be a doctors note on file with the league.

Our rule changes occur every 2 years, and the last set occured in the spring of 2004, which was when the visor rule came into affect.

ref18 is correct.

However, in the pre-game meeting with the coaches, the white hat will ask if there are any tinted visors. If there are (the other 4 officials doing their walkaround will double check all players), then the WH will allow them to play once the HC confirms that the proper papers are in file with the league.

A league doing it's job also provides a list to all WHs who the confirmed players are in the league with tinted visors.