Purpose: The purpose of this study was to explore the heritability of ocular dominance in a classic twin study.
Design: A classical twin study.
Methods: Twins aged 7 to 19 years enrolled from the Guangzhou Twin Registry received comprehensive eye examinations. Ocular dominance was assessed by the "hole-in-the-card test" by trained optometrists. Zygosity of the participants was confirmed by genotyping in all same-sex twin pairs. The pairwise concordance rate was calculated as the main outcome.
Results: After excluding 110 children with anisometropia of 2.0 diopters or greater and 24 children with alternating ocular dominance, a total of 941 twin pairs were identified in the analysis, including 596 monozygotic and 345 dizygotic pairs. Right-eye dominance was present in 59.3% of twins with available data. The pairwise concordance rate was 0.529 and 0.530 in monozygotic and dizygotic twin pairs, respectively (P > 0.5). The tetrachoric correlation was 0.043 and 0.035, respectively. When comparing the young twins and their parents, no significant difference in the percentage of offspring with left-eye dominance was found between right × right parent mating group and non-right × right parent mating groups.
Conclusions: Genetic factors may not be involved in ocular dominance in Chinese teens and children.