Fluctuating Asymmetry And Genomic Homozygosity Of Ocular Parameters In Isolated Island And Urban Populations

This research was conducted as a cross-sectional epidemiological study of the adult population from two isolated islands and an urban city. A total of 2,615 participants from the island of Vis (n=634), the island of Korčula (n=969), and the city of Split (n=1,012) were included in the study. 

Ten ocular parameters were measured in both eyes, including corneal curvature, spherical (SR) and cylindrical refractive errors (without cycloplegia), anterior chamber angle, corneal thickness, anterior chamber depth (ACD), lens thickness (LT), vitreous chamber depth, axial length (AL), and intraocular lens (IOL) power. Blood samples were collected for genetic analysis using single nucleotide polymorphism (SNP) markers. The primary outcome measure was the occurrence of FA, defined GH was assessed using the number and length of runs of homozygosity (ROH). Participants with a history of cataracta surgery, retinal detachment, refractive surgery, or other eye diseases that could influence eye parameters were excluded from the study.

The FA analysis revealed higher FA levels in Vis compared to Korčula and Split. The most pronounced differences (p<0.001) were observed in ACD, AL, and LT. Genetic structure analysis using ROH showed the highest ROH values recorded on Vis, followed by Korčula, and Split. A significant correlation (p<0.001) was found between ROH and FA for ACD, AL, and LT. Mixed model analysis, using the number and length of ROH segments, demonstrated a significant association between homozygosity levels and FA of ocular parameters. Specifically, significant correlations were found for overall FA (p=0.039), SR (p=0.039), AL (p=0.007), and IOL power (p=0.002). In all cases, the significant correlation was observed only with the number of ROH segments.