Comparative study of microcirculatory and structural parameters of the foveal avascular zone in patients with glaucoma and diabetes mellitus

PURPOSE: To study the parameters of the foveal avascular zone (FAZ) and its relationship with the functional, structural and hemodynamic macular indicators in patients with primary open-angle glaucoma (POAG) and type 2 diabetes mellitus.

MATERIALS AND METHODS: The study included 103 patients (161 eyes), who were divided into 3 groups: the 1st group — 58 eyes (31 patients) with 1st stage of POAG and diabetes; the 2nd group — 53 eyes (36 patients) with 1st stage of POAG; the 3rd group — 50 eyes (36 patients) with diabetes. The patients underwent a complete ophthalmological examination, including optical coherence tomography with angiography mode using a Cirrus 5000 Angioplex machine (“Carl Zeiss Meditec”). Functional, structural, hemodynamic parameters, FAZ area, FAZ perimeter, circularity index were evaluated.

RESULTS: The lowest functional indicators were noted in the group of patients with a combined course of POAG and diabetes (best corrected visual acuity (BCVA) 0.63±0.19, MD -4.01±1.52 dB, visual field index 94.69±3.09%) and structural indicators (RNFL 79.91±12.66 μm and GCL+IPL 66.33±15.39 μm), accompanied by a decline in blood density and perfusion (wiPD 28.87±9.08%, wiVD 13.15±3.19/mm), a decrease in FAZ area almost by 2 times (0.62±0.03 mm2), an increase in its perimeter to 3.54±1.57 mm. The circularity index was significantly lower in groups 1 and 3 (0.59±0.11 and 0.58±0.09, respectively) compared with the 2nd group (POAG): 0.66±0.1. The results of the correlation analysis showed a statistically significant inverse dependence of the area and perimeter of FAZ on all hemodynamic parameters.

CONCLUSION: The combined course of POAG and diabetes, even in the initial stages of the disease, is accompanied by pronounced structural changes, deterioration of hemodynamic parameters and impaired microcirculation of the macula. Dynamic monitoring of the area and perimeter of the avascular zone, the circularity index is important for the control and early diagnosis of macular microcirculation disorders, risk assessment and the rate of progression of optic neuropathy in patients with glaucoma.

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