Heritability of central corneal thickness in nuclear families.

PURPOSE Many ocular parameters show strong heritable tendencies. The significance of central corneal thickness (CCT) in the context of glaucoma has been the subject of much debate recently, but its heritability has not been extensively explored. This study was designed to investigate the parent-child heritability of CCT among groups who have CCT considered to be at the extreme ends of the normal range. METHODS Index cases were recruited through a tertiary referral center if their CCT was greater than 578 microm (thick) or less than 510 microm (thin), representing +/-1 SD from a previously published meta-analysis mean of 544 microm (34 microm SD). Subsequently, CCT was measured in all available family members of the index cases. Family units were then analyzed to establish the degree of heritability of CCT from parent to child. RESULTS Thirty-three index cases were included in the analysis (10 >1 SD and 23 <1 SD from the meta-analysis CCT mean). The mean CCT of the children of index cases with a CCT more than 1 SD from the mean (n = 15) and less than 1 SD from the mean (n = 40) was 568 microm (32 microm SD) and 521 microm (22 microm SD), respectively (t = 6.14; P < 0.0001). The parent-child heritability estimate for CCT was h(2) = 0.68 (95% CI, 0.64-0.73). CONCLUSIONS These results indicate that CCT shows strong parent-child heritability, with offspring likely to demonstrate CCT similar to the parental index case.