Three-dimensional choroidal vessels assessment in age-related macular degeneration: a follow-up study

This study evaluated longitudinal choroidal vascular changes in dry age-related macular degeneration (dAMD) eyes using a three-dimensional (3D) algorithm.

Patients underwent swept-source optical coherence tomography during two follow-up visits. Choroidal boundaries and vessels were segmented using the ResUNet model and Phansalkar thresholding. 3D choroidal maps were created and divided into five sectors. Mean choroidal vessel diameter (MChVD), inter-vessel distance (IVD), volumetric choroidal thickness (ChT), and choroidal vascularity index (CVI) were measured in both visits.

This retrospective cohort study included 30 eyes with AMD. The mean age was 72.8 ± 9.55 years. The mean follow-up duration was 11.6 ± 5.02 months. The mean MChVD increased 16.4 µm (6.8%) over time (239.2 ± 19.8 to 255.6 ± 28.2 µm, P = 0.003), particularly in the nasal and temporal sectors (P < 0.05). The mean IVD increased 21.8 µm (10.8%) over time (201.8 ± 29.0 to 223.7 ± 38.2 µm, P = 0.009), which was significant in the nasal, temporal, and superior sectors (P < 0.05). The ChT showed a decreasing trend, though not statistically significant (190.7 ± 58.0 to 183.4 ± 56.8 µm, P = 0.051). The CVI remained stable during follow-up (0.358 ± 0.034 vs. 0.357 ± 0.040, P = 0.933). MChVD positively correlated with the IVD (r = +0.501, P = 0.005). ChT exhibited a negative correlation with IVD (r = -0.426, P = 0.019).

Eyes with dry AMD showed increased MChVD and IVD along with decreased ChT, and we hypothesise that these changes may reflect progressive small-vessel atrophy accompanied by compensatory dilation of larger choroidal vessels during follow-up.