self-vision texter / instrument

According to statistics, the incidence of myopia rate over the world is 22%.
We do need a self-vision measuring instrument to be able to measure our eyesight in our daily life, especially teenagers. The traditional vision measurement need a helper.However, with this self-vision measuring instrument, user can fulfill a vision measurements by oneself.
I designed his self-vision measuring instrument composed of the main part of the self-vision measuring instrument and the direction induction stick, allowing the user to judge the eyesight mark on the screen of the self-vision measuring instrument with the direction induction stick.