Analysis of choroidal thickness and vascularity in patients with unilateral polypoidal choroidal vasculopathy

Purpose: This study aimed to analyze the choroidal characteristics in eyes with polypoidal choroidal vasculopathy (PCV, affected eyes) and unaffected fellow eyes, and investigated the longitudinal changes in the choroidal structure of fellow eyes in patients with unilateral PCV. Methods: We retrospectively reviewed the medical records of 55 treatment-naïve patients with unilateral PCV. The choroidal thickness and vascularity between PCV affected eyes, unaffected fellow eyes, and normal control eyes were compared. Structural changes in the choroid of the fellow eyes were reviewed during follow-up. Results: PCV eyes had thicker subfoveal choroidal thickness (SFCT) (p < 0.001), greater ratio of Haller layer to SFCT (p < 0.001), and lower choroidal vascularity index (p = 0.023), compared to controls. In unaffected fellow eyes, the ratio of the Haller layer to SFCT was greater (p < 0.001) than in controls. During a 58.91-month mean follow-up, nine (16%) fellow eyes developed new PCV. These eyes showed a greater ratio of Haller layer to SFCT at baseline (p < 0.001) compared to the other fellow eyes. We also observed a numerical change in the choroidal vascularity index during follow-up of fellow eyes that developed new PCV. Conclusion: The dilation of the Haller layer was prominent in PCV eyes and fellow eyes, compared to normal controls. In the fellow eyes that developed new PCV lesions, there were changes in the choroidal vascularity during follow-up.