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