COMPUTERIZED VIDEOKERATOGRAPHY OF KERATOCONUS KINDREDS

Objective: To assess the role of heredity in the development of kerato conus. Design: Prospective study, Setting: Eye clinic providing second ary and tertiary ophthalmic care in Toronto. Patients: Thirty-nine pat ients 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) with out clinical evidence or a family history of keratoconus. Outcome meas ures: Three quantitative measures derived from computerized videokerat ography: the relative steepness of the inferior cornea versus the supe rior cornea, central corneal power and the difference in central corne al power between the two eyes. All the data were statistically analyse d with the use of nonparametric discriminant analysis. Results: Fiftee n family members who were believed to be clinically normal on the basi s of refraction, keratometry and slit-lamp examination had statistical ly significant topographic abnormalities suggestive of early or mild k eratoconus. Conclusions: The presence of these findings in family memb ers of patients with keratoconus may represent the incomplete expressi on of a gene contributing to the development of the condition. Pedigre e 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 keratoconu s.