A hand-held ophthalmic device intended to be used by a layperson to measure the refractive error of their eye (the inaccuracies of focusing light upon the retina), typically to test their vision. It is typically in the form of a monocular which contains lenses of different characteristics; a dedicated software providing examination protocols may also be included. The patient changes the lenses and other settings while reading an eye chart to subjectively evaluate which settings give best vision.