Abstract
Purpose :
The study of monozygotic and dizygotic twins, and differences in the correlation of corneal endothelial cell density (ECD) between these groups allows for determination of the extent to which ECD is genetically determined. However, monozygotic twins occur less frequently than dizygotic twins. Here we report the corneal endothelial characteristics from the largest cohort of monozygotic twins to date.
Methods :
Specular microscopy images (Konan Noncon Robo NSP-9900) were captured from 62 pairs of monozygotic (MZ) twins, 96 females and 28 males (mean age 37.2±17.6) (Table 1). We used the flex center method for image analysis, with at least 100 contiguous cells counted per image. Parameters recorded from the system included the central corneal thickness (CCT), mean CD (MCD), mean cell area (MCA), coefficient of variation (CV) in cell area, and percentage of hexagonal cells (Hex (%)).
Results :
Co-twins showed high degree of correlation (r) when compared for mean values of CD, CCT, CV, and cell area in right versus right, left versus left and the average of R and L eyes with mean ECD and mean cell area showing the highest r values of 0.916 and 0.922, respectively (Table 1). There was no significant difference in any of the compared variables between the co-twins using two-sample t-test (p>0.05). Repeating the t-test after stratification of the co-twins based on age groups showed a declining trend in CCT, MCD and Hex and an increasing trend in CV and MCA with increasing age, however it did not generate any significant difference in the same variables between the co-twins (Table 2).
Conclusions :
We present the the largest monozygotic twin study of corneal endothelium to date, demonstrating a higher correlation in cell density than previously reported between such pairs. These findings are consistent with a strong genetic basis to corneal endothelial density. Determination of such genetic factors may strengthen a precision medicine approach to corneal endothelial therapies.
This is a 2020 ARVO Annual Meeting abstract.