Keratoconus & Refractive Corneal Surgery — Practice

A 24-year-old myope is evaluated for refractive surgery. Corneal topography shows inferior steepening with asymmetric bowtie pattern, and there is high astigmatism with against-the-rule skewing; slit-lamp examination reveals a faint vertical line of iron deposition in the deep epithelium near the cone. The iron line described is known as which of the following?