A wavefront aberrometer is used to examine aberrations of the optical system of the eye (cornea and lens). Both myopia and hyperopia as well as astigmatism may be measured with high precision. In particular, higher order aberrations, such as spherical aberration and coma, may be detected. These complex optical aberrations ususally affect patients primarily during twilight or glare. Should a patient report these symptoms, wavefront analysis will be performed.