This paper addresses the concept, measurement and applications of wave aberrations. The ocular optics is not perfect. Apart from conventional low order aberrations (such as defocus and astigmatism) retinal images are degraded by other high order aberrations. Aberrometers typically measure ray deviations at the retinal plane, as a function of pupil position, i.e. local derivatives of the wave aberration. The paper discusses state of the art technology to measure the aberrations of the eye (cornea and crystalline lens), both monochromatic and polychromatic. The aberrometers described include the Hartmann-Shack wavefront sensor, laser ray tracing, spatially resolved refractometer or the corneal aberrations. This technology has been used to advance our understanding on several visual mechanisms, ocular conditions, and corrective methods. Applications include accommodation, myopia, aging, myopia, keratoconus, corneal refractive surgery, cataract surgery or contact lenses.Funding from Spanish Ministry of Science and Technology (FIS2005-04382) and a European Young Investigator Award.Peer Reviewe
