Abstract: This invention concerns a procedure and device for refractometric measurement of the degree of ametropia of a human eye.The device for this invention comprises a light-emitting source combined with a focusing lens, which produces an image of this source on the retina of the eye to be tested, a succession of test lenses which are placed in turn between the eye and the focussing lens, so that the optical axis of the relevant test lens coincides with the optical axis of the eye, and a light-intensity detector placed on this same axis at a fixed distance from the eye, together with means of identifying which test lens causes the detector to emit a signal of minimum intensity.The invention applies to instruments to measure visual acuity, more specifically in handicapped or very young patients.

Abstract: The invention concerns a process and device for measuring the degree of ametropia of an eye.The rays of a luminous source passes through a focussing lens and a test lens in order to create an image on the retina. The rays issuing from the source or from the image pass through a black optical slit and are reflected by at least one reflecting surface defined in a revolving screen driven in rotation by a motor.Application to refractometric instruments for measuring the degree of ametropia of the eye.