In about 6% of patients with keratoconus, there is a history of familial disease. High keratometric astigmatism and mildly irregular mires observed by placidois disc have been suggested to represent variable forms of expression of a gene in family members of patients with keratoconus. We used a computer-assisted digital videophotokeratoscope to map the corneas of 28 family members of 5 patients with keratoconus. Abnormalities observed in family members included central steepening, greater steepening of the cornea inferior to the apex, and substantial asymmetry in the central dioptric power between the two eyes of the same individual. These findings were similar to, but less severe than, those found in patients with keratoconus and may represent the variable expression of a gene contributing to the development of keratoconus. Pedigree analysis in these families suggests an autosomal dominant mode of inheritance.