Purpose: To analyze the evolution of macular vessel density (VD) over 1 year, during early worsening of diabetic retinopathy, in patients with uncontrolled Type 1 diabetes (T1D).
Methods: Retrospective study of 12 eyes of 9 patients with T1D with early worsening of diabetic retinopathy imaged with optical coherence tomography angiography. The following data were collected at the time of pan retinal photocoagulation initiation and after 6 and 12 months: vessel density within three retinal plexuses-superficial vascular plexus, intermediate capillary plexus, and deep capillary plexus; foveal avascular zone area, acircularity index, and flow density (FD)-300; central macular thickness; and HbA1c levels.
Results: A history of rapid reduction in blood glucose was found in seven of nine cases. Vessel density was significantly decreased at 12 months in all plexuses: from 44.68 ± 4.75 to 40.23 ± 7.13 in the superficial vascular plexus (P = 0.008), from 42.72 ± 4.86 to 37.12 ± 8.64 in the intermediate capillary plexus (P = 0.03), and from 22.68 ± 3.93 to 19.66 ± 4.92 in the deep capillary plexus (P = 0.004). Intermediate capillary plexus and deep capillary plexus changes were strongly correlated (r = 0.86, P < 0.001) and were significant as early as 6 months. The mean foveal avascular zone area increased (P = 0.05) and the FD-300 decreased (P = 0.03). No significant change in acircularity index, central macular thickness, and visual acuity were observed over time.
Conclusion: Early worsening of diabetic retinopathy induces a rapid macular capillary dropout mainly affecting the intermediate capillary plexus and deep capillary plexus.