Three-Dimensional Choroidal Vascularity Index in High Myopia Using Swept-Source Optical Coherence Tomography

Area of Science:

• Ophthalmology
• Medical Imaging
• Vascular Biology

Background:

• High myopia is a significant risk factor for vision impairment.
• Choroidal vascular changes are implicated in myopia progression, but detailed characterization is limited.
• Three-dimensional (3D) analysis offers a more comprehensive view of choroidal vasculature.

Purpose of the Study:

• To quantitatively characterize choroidal vasculature in high myopic eyes using 3D choroidal vascularity index (CVI).
• To compare choroidal vascular and stromal features between high myopes (HM) and low to moderate myopes (LMM).
• To investigate the correlation between choroidal characteristics and ocular parameters like axial length.

Main Methods:

• A cross-sectional observational study involving 98 nonpathological myopic patients (46 HM, 52 LMM).
• Swept-source optical coherence tomography (SS-OCT) and OCT angiography were used to image the choroid.
• 3D CVI, choroidal vessel volume (CVV), choroidal stroma volume (CSV), and choroidal thickness (CT) were quantified.

Main Results:

• HM eyes showed significantly reduced 3D CVI, CVV, and CSV compared to LMM eyes.
• Choroidal thinning was observed in HM eyes at subfoveal and macular regions.
• Choroidal characteristics were negatively correlated with axial length but not spherical equivalent.

Conclusions:

• High myopia is associated with reduced 3D choroidal vascular and stromal components, independent of myopic maculopathy.
• Axial length is a key determinant of these choroidal changes.
• 3D CVI analysis provides novel insights into the pathophysiology of nonpathological high myopia and aids in monitoring disease progression.