The effects of vitamin B12 deficiency on retina and optic disk vascular density

In this study, we aimed to determine the alterations in the retina and peripapillary vascular density in patients with vitamin B12 deficiency.

The patients were divided into two groups regarding their vitamin B12 levels as the low vitamin B12 group (< 200 pg/ml) and the normal vitamin B12 group (≥ 200 pg/ml). The retinal nerve fiber layer thickness (RNFLT) and the central macular thickness (CMT) were measured through an SD-OCT analysis. The foveal avascular zone (FAZ), vessel density (VD) of the superficial capillary plexus (SCP), and deep capillary plexus (DCP) of the macula, and the VD of the radial peripapillary capillary plexus (RPCP) for the optic disk were determined by OCT-A.

Thirty-three patients were in the low vitamin B12 group and 54 were in the normal group. The mean RNFLT measurements were significantly lower in the low vitamin B12 group (p = 0.001). The RPCP values in all quadrants were significantly lower in the patients with vitamin B12 deficiency (p = 0.001); moreover, there was a significant increase in the FAZ value with a decrease in both superficial (p = 0.001) and deep (p = 0.001) VDs. There was a significant positive correlation between the serum vitamin B12 levels and the RPCP values and superficial and deep VDs, while the FAZ value was negatively correlated with the vitamin B12 levels.

Vitamin B12 deficiency has diverse effects on ocular structures and retinal vasculature. Decreased VDs and increased FAZ may be associated with severe ocular alterations in the long term, which should be further investigated.