Choroidal volume decrease associated with stromal regression in adult myopia: A high-resolution optical coherence tomography angiography study.

PURPOSE: Observing choroidal volume changes in myopia with various degrees via spectral-domain optical coherence tomography (SD-OCT) images.

METHODS

215 eyes of 118 myopia patients were divided into 3 groups according to spherical equivalent: low myopia (LM), moderate myopia (MM) and high myopia (HM). Choroidal thickness (CT), choroidal volume (CV), vascular volume (VV), stromal volume (SV), choroidal vascular index (CVI), and mean choroidal vascular diameter (CVD) in the Haller and Sattler layers were measured. Choroidal capillary (CC) blood flow deficit percentage (FD%) was measured using Sauvola local threshold method through Enface images.

RESULTS

As myopia degree increased, CT, CV and SV decreased, while CVI increased, CVD remained unchanged, and VV decreased significantly in the nasal and superior regions. Foveal CC FD% of HM was higher than that of LM and MM (P <0.05). The CCFD% of HM in the superior and total macular area also increased compared with MM (P <0.05). SE was positively correlated with CT, CV, and SV, while negatively correlated with CVI. CT was significantly correlated with SV and VV. And, the mean CT (P <0.05) and axial length (P <0.001) were the independent protection and risk factors for HM. ROC curve area was 0.800, with cutoff values of 75.11Px for CT and 26.24mm for axial length.

CONCLUSION

With myopia progression, the average choroidal thickness and volume decreased, primarily due to reduced stromal volume.