Full Title

Apparatus for testing the eyes; Instruments for examining the eyes (eye inspection using ultrasonic, sonic or infrasonic waves A61B8/10) > Subjective types, i.e. testing apparatus requiring the active assistance of the patient > for testing visual acuity; for determination of refraction, e.g. phoropters > Devices for presenting test symbols or characters, e.g. test chart projectors (A61B3/036 takes precedence)