The cornea is a transparent outer covering of the eye. When it starts thinning, it becomes a ticking bomb, a risk factor for blindness. The cornea is a transparent outer covering of the eye.

Pellucid Marginal Degeneration. Classic pellucid marginal degeneration (PMD) has clinical features consisting of a zone of inferior corneal thinning within 2-3 mm of the inferior limbus.

Theoretically, this leaves most of the corneal nerves intact and should lead to superior post-operative preservation of corneal sensitivity than previous photorefractive procedures. SMILE was also ...