Autorefractor is a computer-controlled machine used during an eye examination to provide an objective measurement of a person’s refractive error and prescription for glasses or contact lenses. This is achieved by measuring how light is changed as it enters a person’s eye.

Autorefractor are used to measure the degree of refractive error in the eye, and are suited well toward applications such as differentiating corneal from lenticular aberrations, and assessing pre-and-post refractive surgery patients.

An keratometer, is a diagnostic instrument for measuring the curvature of the anterior surface of the cornea, particularly for assessing the extent and axis of astigmatism.

Keratometry is a procedure used to measure the curvature of the cornea (corneal curvature). It is performed by an ophthalmologist, with the aid of a device known as keratometer. No special preparation is required, on the part of the patient.