Size of the physiologic cup of the optic nerve head. hereditary and environmental factors
J. T. Schwartz, F. H. Reuling and M. Feinleib
This study provides a quantitative assessment of heritability of size of
the normal physiologic cup when estimated as a continuous variable. A
horizontal cup-disc ratio was estimated clinically among a sample of 37
pairs of monozygotic (MZ) and 26 pairs of like-sexed dizygotic (DZ) twins.
Differences in intrapair variance and intraclass correlation coefficient
between the MZ and the DZ samples were large and highly significant, and
suggest that inheritance plays a major role in determining diameter of the
normal physiologic cup. Values of heritability index (Hl, an estimate of
the proportion of variance within pairs explained by genetic factors)
ranged from 0.60 to 0.80 by various computational methods employed.
