Capturing the transition from intermediate to neovascular AMD: Longitudinal changes in choroidal volume and choroidal vascularity index.

Background: To perform a three-dimensional assessment of the choroid, including choroidal volume and choroidal vascularity index (CVI), during the transition from intermediate to neovascular age-related macular degeneration (AMD), and following anti-VEGF therapy.

Methods: A total of 42 participants (42 eyes) with intermediate AMD at baseline who developed neovascular AMD within 3 months were included in the analysis. Optical coherence tomography (OCT) scans at follow-up visits (after transition to neovascular AMD and 12 months after the initiation of anti-VEGF therapy) were compared with values at the latest visit with evidence of intermediate AMD to quantify longitudinal choroidal changes. Enhanced depth imaging (EDI) OCT scans were analyzed to obtain the following metrics: (i) choroidal volume, (ii) choroidal stromal volume, (iii) choroidal vascular volume, and (iv) CVI.

Results: At baseline, the mean (median; IQR) choroidal volume (i.e., including both the stromal and vascular components) was 0.156 mm³ (0.149; 0.065), increasing to 0.163 mm³ (0.148; 0.068) at the follow-up when treatment-naïve exudative MNV was first detected (p = 0.013). After 12 months of anti-VEGF therapy, it returned to near-baseline levels at 0.156 mm³ (0.146; 0.065; p = 0.457). Similarly, the choroidal stromal and choroidal volumes increased at MNV detection but returned to baseline after treatment. Conversely, no alterations in CVI were observed between the baseline and follow-up visits.

Conclusion: The transition from intermediate to exudative neovascular AMD is associated with a significant increase in choroidal volume, affecting both stromal and luminal components. After anti-VEGF treatment, these changes regress, returning to baseline levels.