Certain Glasses Make a Difference

I helped a gentleman yesterday with his swing for a few minutes.  He's an accomplished player and wanted to test a product.  While watching him, he hit 5 shanks in a row.  Finally, he looked back at me and said either this product is no good or I can't hit it anymore.  I asked him if the glasses he was wearing were bifocals.  He said yes, that he normally plays golf with a different pair of glasses.  He took the bifocals off and proceeded to hit the ball the way he usually does. 
The moral to the story is that bifocals and golf don't mix.  With bifocals you have such a small window at the bottom of the lense to look through.  It effects your posture and your depth perception.  I always question my students if they have glasses on.  If you do wear bifocals to golf,  visit your eye doctor and get a pair of sport specific glasses.  It will be worth the visit.