Thickness profile of the ganglion cell complex and choroid in patients with persistent diabetic macular edema

About 40 % of patients with diabetic macular edema (DME) do not respond optimally to first-line treatment with intravitreal injection of anti-vascular endothelial growth factor (AVEGF). Evidence suggests that additional vascular and neurodegenerative mechanisms may be involved. This study aimed to characterise the thickness of the Ganglion Cell Complex (GCC) and investigate the Choroidal Vascularity Index (CVI) in patients with different patterns of therapeutic response to AVEGF DME.

This cross-sectional study included 27 diabetic patients into 3 different groups based on their response to AVEGF therapy: control group, responder DME group, and persistent DME group. The study's approach to vascular and neurodegenerative imaging biomarkers involved three steps: (1) Automatic quantification of GCC thickness, with manual correction when necessary; (2) Semi-automatic measurement of choroidal thickness; and (3) Analysis of choroidal area and choroidal luminal area using ImageJ software to calculate the CVI.

In the overall characterization of the sample, a significant difference was observed only in the Best Corrected Visual Acuity (BCVA). There was a significant difference in Average Retinal Thickness (1 mm, 3 mm, and 6 mm) between the 3 groups and in GCC thickness at 1 mm. BCVA was negatively correlated with mean retinal thickness, while CVI showed a potential positive correlation with BCVA.

While demographic and general clinical characteristics showed minimal differences across the groups, important differences in GCC and choroidal characteristics were observed. GCC (1 mm) may be interesting to explore in predicting visual outcomes after treatment, and CVI may impact visual gain.