Keratoconus with pellucid marginal corneal degeneration.

Examination of 1,625 Japanese patients with keratoconus and 20 patients with pellucid marginal corneal degeneration showed that 17 patients with pellucid degeneration also had keratoconus in the central portion of the cornea. Three patients with pellucid degeneration without keratoconus showed bilateral involvement. Among the 17 cases of pellucid degeneration with keratoconus, eight patients showed bilateral involvement and the others showed unilateral involvement. Pellucid marginal corneal degeneration with or without keratoconus may be a variant of keratoconus or a different manifestation of the same etiologic factor.