Peripapillary Bruch's membrane Opening-Minimum Rim Width (BMO-MRW) and microvascular changes in early diabetic retinopathy.

BACKGROUND

To evaluate changes in peripapillary Bruch's Membrane Opening-Minimum Rim Width (BMO-MRW) and its association with peripapillary microvascular in patients with early diabetic retinopathy (DR).

METHODS

This observational cross-sectional study included 105 eyes from 105 diabetic patients, comprising 55 eyes without diabetic retinopathy (No-DR group) and 50 eyes with mild diabetic retinopathy (Mild-DR group). An additional 50 eyes from 50 healthy individuals served as the Control group. All eyes underwent optical coherence tomography (OCT) radial scanning to assess Bruch's membrane opening-minimum rim width (BMO-MRW) and OCT-angiography (OCTA) with a 6 mm × 6 mm scan centered on the optic disc to evaluate perfusion density (PD) and vessel density (VD). OCTA measurements were calibrated based on the FoBMO axis and analyzed using the ETDRS grid. The associations between BMO-MRW and PD/VD were subsequently investigated.

RESULTS

The mean BMO-MRW values were significantly lower in the No-DR (305.78 ± 35.12 μm) and Mild-DR groups (299.42 ± 37.33 μm) compared to the control group (323.56 ± 40.33 μm, P = 0.005), with significant thinning in the superotemporal and inferotemporal quadrants (P = 0.039, 0.047). PD in the inner ETDRS grid decreased from (56.01 ± 10.53)% in the control group to (52.16 ± 8.75)% in the No-DR group and (47.91 ± 12.95)% in the Mild-DR group (P = 0.001), while in the outer ETDRS grid, it declined from (42.92 ± 6.70)% to (40.20 ± 7.24)% and (38.13 ± 8.78)%, respectively (P = 0.008). VD in the inner ETDRS grid showed a reduction from (15.41 ± 2.68) mm⁻¹ in the control group to (14.39 ± 2.17) mm⁻¹ in the No-DR group and (13.55 ± 2.98) mm⁻¹ in the Mild-DR group (P = 0.001), while in the outer ETDRS grid, it decreased from (13.74 ± 2.26)mm⁻¹ to (12.78 ± 2.53)mm⁻¹ and (12.09 ± 2.83)mm⁻¹, respectively (P = 0.006). Significant reductions in PD were observed in the nasal quadrant of the inner ring and the supratemporal quadrant of the outer ring, while VD showed significant decreases in the nasal quadrants of the inner ring and the supratemporal and inferotemporal quadrant of the outer ring. Moreover, BMO-MRW was positively correlated with PD (r = 0.583, P = 0.001) and VD (r = 0.499, P = 0.001) in the inner ring, with positive correlations observed between BMO-MRW and inner PD and VD in the counterpart quadrants.

CONCLUSIONS

Peripapillary BMO-MRW is significantly reduced in early DR, particularly in the superotemporal and inferotemporal quadrants, alongside declines in PD and VD. The positive correlation between BMO-MRW and microvascular parameters suggests its potential as a biomarker for early DR detection and monitoring.