Impact of vitamin B12 deficiency on macular and choroidal vascular structures

Vitamin B12 deficiency can affect macular and choroidal vasculature. Optical coherence tomography angiography (OCTA) and enhanced depth imaging OCT (EDI-OCT) are essential for early detection and monitoring of these microvascular changes, helping to prevent potential visual impairment.

This study aimed to assess the impact of vitamin B12 deficiency on the vascular structures of the macula and choroid by using OCTA and EDI-OCT.

This prospective cross-sectional study included 34 individuals with vitamin B12 deficiency and 36 healthy participants as the control group. Macular vascular parameters, including superficial capillary plexus (SCP) and deep capillary plexus (DCP) vascular densities, and foveal avascular zone (FAZ) metrics, were measured using OCTA. The choroidal structure was assessed using EDI-OCT to calculate the total choroidal area (TCA), luminal area (LA), stromal area (SA), and choroidal vascularity index (CVI).

Compared with the control group, patients with vitamin B12 deficiency showed significantly higher vascular densities in the SCP of the parafoveal superior quadrant, as well as in the DCP of the parafoveal superior hemi and superior quadrants (p = 0.03, p = 0.04, and p = 0.01, respectively). The remaining OCTA parameters did not exhibit any statistically significant variation between the groups. Choroidal assessment showed notable decreases in TCA, LA, SA, and central subfoveal choroidal thickness. Moreover, patients with vitamin B12 deficiency showed a significant increase in the CVI (all p ≤ 0.01).

Vitamin B12 deficiency is associated with complex alterations in macular and choroidal vascularity, including localised increased macular capillary densities and a paradoxical increase in the CVI despite decreased choroidal thickness.