Slit lamp biomicroscopy is an excellent case study of this progress. The coupling of photography to the slit lamp biomicroscope allowed clinicians to create permanent impressions of an exam, and these images became the preferred media for communicating clinical findings. Clinical atlases illustrating normal eyes and diseases of the anterior segment emerged. With the introduction of digital image acquisition, edge-detection algorithms allowed quantitative characterization of the anterior and posterior corneal surfaces, which provided the geometric information necessary to reconstruct surface elevations, curvatures, and thicknesses across a two-dimensional optical section. More recently, video acquisitions of rotating Scheimpflug sections [e.g., the Pentacam (Oculus) and the Galilei (Ziemer Ophthalmic Systems)] or horizontally scanning vertical slit beams [Orbscan (Bausch & Lomb Surgical)] have combined multiple two-dimensional sections to reconstruct the three-dimensional anatomy of the cornea. Similar advances are also occurring in the measurement of the anterior chamber, iridocorneal angle structures, and the lens. This chapter presents an overview of major imaging approaches in refractive surgery, including computerized videokeratography, arc-scanning ultrasound, Scheimpflug imaging, and anterior segment OCT. The focus is on clinical utility as well as caveats for practitioners who rely on the information these technologies provide.