It is a staging (grading) display for keratoconus. In the 1950s the Amsler-Krumeich staging system for keratoconus was developed and is still frequently used today. However the Amsler-Krumeich only takes anterior curvature and central corneal thickness into consideration. The ABCD Keratoconus Staging display is a newly developed display, approved by the four major ophthalmology societies in the world. It looks at A – anterior curvature, B – back (posterior) curvature, C – corneal thickness and D – distance corrected visual acuity. Keratoconus is a progressive disease; this display detects progression easily aiding the clinician to treat patients more successfully.