My informant learned this superstition when she was very young, so she doesn’t recall when she learned it.  She has been taking part of this superstition ever since she was in elementary school, where she probably learned it from a friend.  Whenever she sees a stray eyelash other people’s faces, she takes the eyelash, puts it on their finger and tells them to make a wish and blow the eyelash off.  She puts the eyelash on her finger if she finds an eyelash on her face and follows the same procedure.
She said that she does not believe in this superstition, yet she does it anyway.  According to her, there is no validity to this superstition, so she doesn’t believe her wishes will come true.  She believes that this eyelash superstition exists because losing an eyelash is more unusual than losing strands of hair.  Wishing with a strand of a hair would definitely not be as special because people lose many strands of hair everyday.
She tells this superstition because it has become a routine if she sees a loose eyelash.  It has become embedded in her that she has an automatic reaction to tell it.
Like the superstition of making a wish at 11:11, I do not necessarily believe that blowing an eyelash off my finger while making a wish will make my wish come true.  The willingness of a person to make his or her wish happen is what makes a wish come true.  Usually people do not rely on an eyelash wish, so they take action and make it happen.  I believe that eyelash wishing does contribute to making a wish become reality, but a person’s actions are what makes it become reality.