Autorefractor/keratometers (ARKs) are computerized devices that provide both refractive testing and keratometry measurements. Keratometers, also known as an ophthalmometers, measure the image size reflected from two points on the surface of the cornea to determine its curvature, and thus a patient's astigmatism.
Auto Refractometer Keratometer is traditionally used to measure the level of refractive error in the eye such as differentiating corneal out of lenticular aberrations and checking pre-and-post refractive surgery patients. Auto Refractometer Keratometer is a machine utilized during an eye examination to provide an objective dimension of a person’s refractive error and the prescription for eyeglasses or contact lenses.
Keratometry works on the principle of recording the image size reflected from a known-sized object. Given the object size and distance from image to object, the radius of curvature of the cornea can be calculated.