SUPERFICIAL AND DEEP VASCULAR COMPLEXES DAMAGED TO DIFFERENT EXTENTS IN ADVANCED STAGES OF DIABETIC RETINOPATHY

To identify the extent of damage to the superficial vascular complex and deep vascular complex as the stage of diabetic retinopathy (DR) increases.

Subjects were divided into four groups: patients with type 2 diabetes without DR (Group 1), those with mild-to-moderate nonproliferative DR (Group 2), those with severe-to-very severe nonproliferative DR (Group 3), and those with proliferative DR (Group 4). The vessel densities of the superficial vascular complex (superficial vessel density, SVD) and deep vascular complex (deep vessel density, DVD) and their ratios were compared. Linear regression analyses were used to identify factors associated with the SVD/DVD ratio.

The SVDs were 25.5% ± 6.1%, 25.1% ± 7.0%, 24.5% ± 9.0%, and 21.6% ± 6.9% (P = 0.048); the DVDs 25.6% ± 5.3%, 23.0% ± 7.0%, 22.3% ± 8.8%, and 17.5% ± 5.0% (P < 0.001); and the SVD/DVD ratios 1.00 ± 0.16, 1.12 ± 0.20, 1.14 ± 0.33, and 1.24 ± 0.27 (P < 0.001) in Groups 1 to 4, respectively. In multivariate analysis, DR severity (B = 7.16, P < 0.001) and the HbA1c level (B = 1.57, P = 0.042) were significantly associated with the SVD/DVD ratio.

Both the SVD and DVD tended to decrease in the advanced stages of DR, and the SVD/DVD ratio increased, indicating more severe damage to the deep vascular complex than the superficial vascular complex. The ratio was positively associated with the HbA1c level, indicating a significant relationship between that level and DVD rather than SVD damage.