It's worth noting that with Optotypes, the goal of having clear and unambiguous letters is inverted. The aperture of C, for example is much narrower than the co

It's worth noting that with Optotypes, the goal of having clear and unambiguous letters is inverted. The aperture of C, for example is much narrower than the comparable types because the objective is to see if the viewer's eye is able to distinguish the closed-aperture C from O.