Wearing a monocle is generally not uncomfortable. If customised, monocles could be worn securely with little effort. However, periodic adjustment is common for monocle wearers to keep the monocle from popping, as can be seen in films featuring Erich von Stroheim. Often only the rich could afford to have a monocle custom-fabricated, while the poor had to settle for ill-fitting monocles that were less comfortable and less secure. The popular perception was (and still is) that a monocle could easily fall off with the wrong facial expression. This is true to an extent, for example raising the eyebrow too far will allow the monocle to fall.