A device for stabilizing the constant accommodation of an eye comprises a target object, an optical unit, and an additional optical unit. The target object is set up to be fixated by a patient along an optical axis. The optical unit is set up along the optical axis to compensate for a spherical ametropia of the eye. The additional optical unit is set up along the optical axis to compensate for an astigmatic ametropia of the eye. The additional optical unit comprises at least two cylindrical lenses and at least four deflection prisms. At least one cylindrical lens is rotatably arranged about the optical axis. At least one deflection prism can be adjusted to change the optical path length of the light path from the target object to the eye.
