A new study on early choroidal lesions in NDR patients was published in "Photodiagnosis and Photodynamic Therapy". Choroidal parameters including the thickness and VD of the choroid was compared between NDR patients (T2DM without DR) and normal control. Reduced choroidal thickness and CVI in the peripheral choroid indicated that general atrophy in the peripheral large and medium choroidal vessels (LMCV) was more significant in the preclinical or early DR patients! Meanwhile, compared with 2D choroidal vessel density, 3D indicators (such as CVI) were more sensitive for detecting diabetic choroidopathy!

In addition, both peripheral CVI and choroid thickness reduction correlated with age and the duration of diabetes, indicating that diabetic choroidopathy might relate to DM course and DR onset and further influence the function of the retina.  
All these findings gave us more evidence that early choroidal lesions tend to be peripheral in LMCV even before DR and correlate with age and the duration of diabetes. "UWF full-range SS-OCTA and 3D parameters could markedly advance the study of choroid!"

A 400kHz speed swept-source OCTA (BMizar, TowardPi Medical) was used in this study to achieve high-resolution 24mmx20mm choroid OCTA (HD mode within 15 seconds). Automatic quantification parameters including the thickness, 2D-vessel density and 3D indexes (including CVI, CVV/a, CSI, CSV/a) of choroid were analyzed in 3x3 grids (as shown).
(CVV/a refers to choroid vessel volume per unit area, CVI is defined as the ratio of CVV to the total choroid volume, CSV/a refers to the choroid stromal volume per unit area, CSI is defined as the ratio of CSV to the total choroid volume.)

This study was authored by DR. Xiaowen Deng and others, including the team of Prof. Yuqing Lan, from Sun Yat-sen Memorial Hospital, Sun Yat-sen University.
Full text link: https://www.sciencedirect.com/science/article/abs/pii/S1572100023005501