Check some of the dirt track racing suppliers for "tear-offs". They're thin plastic covers that fit over crash helmet face shields to help a driver clear his vision during a race. They're very inexpensive, and several layers of them can be stacked up without distorting one's vision. Try shopping for them at online race suppliers like JEGS or Racer's Wholesale.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!