Computerized videokeratography of keratoconus kindreds.

OBJECTIVE

To assess the role of heredity in the development of keratoconus.

DESIGN

Prospective study.

SETTING

Eye clinic providing secondary and tertiary ophthalmic care in Toronto.

PATIENTS

Thirty-nine patients with keratoconus (57 eyes) and 48 relatives of 11 patients with keratoconus. The corneal topography of the family members was compared with that of a group of 68 volunteer control subjects (136 eyes) without clinical evidence or a family history of keratoconus.

OUTCOME MEASURES

Three quantitative measures derived from computerized videokeratography: the relative steepness of the inferior cornea versus the superior cornea, central corneal power and the difference in central corneal power between the two eyes. All the data were statistically analysed with the use of nonparametric discriminant analysis.

RESULTS

Fifteen family members who were believed to be clinically normal on the basis of refraction, keratometry and slit-lamp examination has statistically significant topographic abnormalities suggestive of early or mild keratoconus.

CONCLUSIONS

The presence of these findings in family members of patients with keratoconus may represent the incomplete expression of a gene contributing to the development of the condition. Pedigree analysis suggested an autosomal dominant inheritance pattern in 9 of the 11 families. Our results underline the value of videokeratography for accurate family pedigree analysis and the diagnosis of keratoconus.