Pellucid marginal degeneration is a corneal ectatic disorder primarily involving the peripheral inferior quadrant from the 4 o’clock to 8 o’clock position.
The inferior crescent-shaped thinning of the cornea (Figure 1) is marked by normal corneal thickness just above the ectatic area, characteristically differentiating it from keratoconus. The crescent band of corneal thinning is around 1 mm to 2 mm from the limbus and noninflammatory in nature, with the disorder typically manifesting between the second and fifth decade of life with increased prevalence in men. The inferior bulge