Association between ABO and Rh blood groups and choroidal structural parameters in adult population

The ABO and Rh blood group systems have been associated with various systemic and ocular diseases. The choroid, as the most vascularized ocular structure, plays a critical role in retinal health. The choroidal vascularity index (CVI) has emerged as arobust metric for evaluating choroidal structure. This study aimed to investigate the association between ABO and Rh blood groups and choroidal structural parameters, including CVI, in a healthy adult population.

This prospective study included 164 healthy participants who underwent comprehensive ophthalmologic examination, including enhanced depth imaging optical coherence tomography (EDI-OCT). Subfoveal choroidal parameters-stromal area (SA), luminal area (LA), total choroidal area (TCA), and CVI-were measured using Image-J software. Participants were grouped according to ABO and Rh blood types. Statistical comparisons were conducted using Kruskal-Wallis, Mann-Whitney U, Chi- Square, and Spearman correlation tests.

Among the 164 participants (55.5% female), blood type distributions were: A (36.6%), B (20.1%), AB (15.9%), and O (27.4%). Statistically significant differences were found between ABO blood groups for SA, LA, and TCA (p < 0.05). Blood group B exhibited significantly higher SA, LA, and TCA compared to other groups. However, CVI did not differ significantly among ABO or Rh groups (p > 0.05). No correlations were observed between age or axial length and choroidal parameters.

While SA, LA, and TCA values vary across ABO blood groups-particularly elevated in blood group B-CVI remains stable, suggesting a proportional expansion of stromal and vascular components. These findings imply a potential genetic influence of blood group antigens on choroidal morphology without affecting vascular density. Further large-scale, multiethnic studies are warranted to validate these associations.