Unraveling the Heritability of Ocular Rigidity and Myopia-Related Traits: A Siblings-Based Study.

Purpose: Ocular rigidity (OR) is a macroscopic biomechanical parameter that represents the distensibility of the ocular globe, particularly of the sclera. To better understand the role of OR in refractive development, this study aimed to quantify the heritability of OR and other myopia-related traits in healthy siblings. Methods: A validated method based on video rate choroidal optical coherence tomography imaging and dynamic contour tonometry was used to measure OR in siblings. We estimated heritability of OR, as well as IOP, ocular pulse amplitude, axial length, spherical equivalent refraction, submacular choroidal thickness, pulsatile choroidal thickness change, and pulsatile choroidal volume change, using maximum likelihood variance components methods. Results: Forty-five subjects (21 sibling groups, 58% female, 47% with myopia) aged 11.7 ± 4.9 years were included in this study. Crude heritability estimates for OR were 0.59 (95% confidence interval [CI], 0.32-0.81; P = 0.0003) without adjustments, and 0.59 (95% CI, 0.33-0.81; P = 0.0002) after adjusting for age and sex. Unadjusted heritability estimates were 0.49 (95% CI, 0.20-0.78) for IOP, 0.33 (95% CI, 0.09-0.71) for OPA, 0.57 (0.30-0.80) for axial length, 0.03 (0.00-0.99) for spherical equivalent refraction, 0.51 (95% CI, 0.24-0.77) for choroidal thickness, 0.45 (95% CI, 0.18-0.75) for pulsatile choroidal thickness change, and 0.40 (95% CI, 0.14-0.73) for pulsatile choroidal volume change. Conclusions: This study presented the first quantification of heritability for OR, indicating substantial familial aggregation of OR among siblings. While these findings can have implications in myopia, further investigation is needed to determine the influence of familial factors, both genetic and environmental, on the sclera.