The anterior corneal mosaic is the pattern produced by massage of the cornea through the closed eyelids following the instillation of fluorescein sodium. This pattern has been observed without lid manipulation in eyes with keratoconus wearing hard contact lenses. Thirty-three (75%) of the 44 eyes with keratoconus wearing hard contact lenses spontaneously demonstrated the presence of the anterior corneal mosaic pattern; the pattern occurred spontaneously in two (5%) of 40 eyes in the control group of normal corneas. The mechanism by which the anterior corneal mosaic pattern is produced by hard contact lens wear provides an explanation of the high incidence of this pattern in eyes with keratoconus wearing hard contact lenses.