Longitudinal changes in parafoveal microvascular structure in diabetic macular edema

Abstract

Aim: This study aims to investigate retinal microvascular changes according to increases and decreases in macular edema, explain how these changes are associated with different capillary plexuses in diabetic macular edema (DME), and provide evidence for treatment efforts.

Materials and Methods: 21 eyes of diabetic patients with DME who were treated with intravitreal injections were investigated. The control group was assigned age-and sex-matched healthy subjects. The patients were divided into decreased edema and increased edema subgroups to compare microvascular changes before and after treatment. Optical Coherence Tomography Angiography (OCTA) parameters were used for comparison.

Results: There were significant differences in visual acuity and mean OCTA parameters between the main patient group and the control group (all P<0.05). There were no significant differences between the two DME subgroups in terms of baseline values (all P>0.05). The foveal avascular zone (FAZ) in the deep capillary plexus (DCP) was significantly lower in the decreased edema group; however, there were no significant differences in the other parameters between the two subgroups after 6 months of treatment. The changes in the FAZ in the DCP ranged from 2126.82 ± 1858.59 μm2 to 711.64 ± 738.55 μm2 in the decreased edema group (P = 0.013) and from 2231.50 ± 2187.66 µm2 to 2025.50 ± 2020 µm2 in the increased edema group (P = 0.575) after 6 months of treatment.

Conclusion: Deep retinal ischemia can actually recover after proper treatment. However, we were unable to find a significant change in the density of the parafoveal vessel in DME after treatment; the changes in the FAZ of the DCP were the most prominent indicator of that improvement.