After considering the cornea in overview, one should examine the anterior segment with the “optical trident” (focal, indirect lateral and retroillumination) to ensure that even discrete corneal changes such as fine opacities or endothelial dew are recognized. In addition, one should assess the depth of the change using an optical section. Fluorescein is also an important supplementary diagnostic tool in corneal assessment: Not only can one detect the smallest epithelial lesions, but one can also impressively demonstrate painful surface defects to the patient. The optical quality of the surface can be checked by its reflective properties when a mirror reflex is slid over it. Finally, from the arrangement of the 1st and 2nd Purkinje images, one can infer previously performed refractive procedures and detect an early keratoconus with the help of the Tick-test.