The most accurate way to pick up early keratoconus is to use a device called a corneal topographer. A topographer uses imaging processing techniques to automatically determine the cornea’s shape. Some topographers only measure the front surface of the cornea, and may fail to detect early keratoconus, because in early keratoconus the shape of the front of the cornea may be normal while the back of the cornea is abnormal. The Wellington Eye Centre uses the Pentacam, which can measure both the front and the back of the cornea.