It is important to note that BAD is an early ectasia risk screening tool often used to screen possible refractive candidates.
The population being screened for refractive procedures due to their eye condition by their very nature will have a higher incidence of ectasia risk.
A cornea at risk of ectasia, may - if left untouched - never develop ectasia, however, if undergoing refractive treatment, will develop ectasia.
The incidence of yellow “Final D” is therefore higher than the occurrence of keratoconus.