The impact of systemic iron overload on retinal and choroidal microcirculation in transfusion-dependent beta-thalassemia patients

This study aimed to evaluate retinal and choroidal microcirculation in transfusion-dependent β-thalassemia (TDβT) patients and to explore associations between systemic iron overload and ocular structural and vascular changes.

A total of 66 eyes from 33 TDβT patients and 66 eyes from 33 healthy controls were included in this case-control study. Retinal and choroidal structures were evaluated using Spectral-Domain OCT and OCT-Angiography (OCTA). Systemic iron overload was assessed using serum ferritin and MRI-T2* of the liver and heart. Liver iron load was classified by T2* values into normal, mild, and moderate. Key ocular parameters, including central macular thickness (CMT), subfoveal choroidal thickness (SCT), luminal area (LA), stromal area (SA), total choroidal area (TA), and vessel density (VD) of superficial (SCP), deep (DCP), and choriocapillaris (CC) plexi, were analyzed.

Choriocapillaris VD was significantly lower in TDβT patients compared with controls (p < 0.001, p adjusted = 0.004), while ferritin levels showed positive correlations with CMT, SCP VD, and CC VD within the patient group. Patients with moderate liver iron overload showed increased trend toward LA, SA, TA, SCT, and inferior peripapillary VD, but this significance not existed after FDR correction. No significant relationship was found between iron overload and FAZ metrics.

Liver iron overload may be associated with changes in choroidal structure and perfusion in TDβT patients, although chronic anemia-related hypoxia and compensatory vascular responses may also contribute to these findings.Choroidal parameters may provide useful non-invasive indicators for monitoring ocular effects of systemic iron burden.