1. A refractometer for determining the refraction properties of an eye of a patient, comprising: an optical projection device that comprises at least one light source that produces a light pattern, wherein the light pattern of the projection device is projected on the retina of the eye and focused thereon, an optical viewing device that comprises at least one photoelectric sensor, wherein the optical viewing device views the light pattern reflected on the retina of the eye through the cornea and the lens of the eye and wherein the light pattern is projected on the photoelectric sensor in the form of an image pattern, an evaluation device for evaluating the image pattern recorded by the photoelectric sensor and deriving the refraction properties of the eye, and a distance measuring device for determining the distance between the refractometer and the patient, wherein the distance measuring device is able to measure the distance between the refractometer and the eye, and wherein the distance measuring device includes a slit projection device to illuminate the eye and a Scheimpflug camera to record split images of the eye, wherein the distance between the refractometer and the eye is derived from the split images of the eye.