Any condition where the corneal thickness may be abnormal such as keratoconus, post-refractive surgery ectasia and Fuchs dystrophy. Keratoconus and corneal ectasias are diagnoses that can cause progressive corneal thinning. Fuchs dystrophy can cause progressive corneal thickening.
It is usually performed using ultrasound. It is a rapid, in-office procedure that requires topical anesthesia.