Cheng Sim Anna Tan, Kelvin Teo, Kavya Devarajan, Xian Hui Lim, Zhang Yu, Gavin Tan, Marcus Ang, Tien Yin Wong1, Gemmy Cheung
Purpose: To validate a novel quantiftcation of mean choroidal vessel width index (MCWI) measured on en face structural optical coherence tomogra- phy (OCT). Background: OCT B-scans may not fully measure choroidal vessel width in the assessment of pachy- choroid disease (e.g. polypoidal choroidal vasculo- pathy and central serous chorioretinopathy).
Methods: En face structural OCT images at the Hal- ler?s layer in the choroid were obtained from patients with pachychoroid disease and a control group of normal eyes. Control eyes had OCT images taken on 3 different OCTA platforms. 20 and
50 micron slabs were captured in all eyes. The MCWI was calculated based on the ratio of total pixel area of the overall choroidal vessels to the ske- letonised branch length of the same image.
Results: Preliminary data of 5 eyes in each group, after adjusting for difference in resolution showed that there was a signiftcant difference between MCWI calculated in normal versus eyes with pachy- cohoroid disease (20 microns:7.44 vs 18(p<0.05), 50 microns:7.93 versus 20.13(p<0.05). Normal eyes measured with the 3 different OCT platforms showed consistent values with no signiftcant differ- ence between readings in the same eye between each different OCT platform (p=0.36). Conclusions: MCWI measured on en face OCT was signiftcantly higher in eyes with pachychoroid dis- ease compared to normal controls. MCWI may be a useful measure of the overall choroidal vascular thickness on en face OCT, even on different OCT platforms, and may allow assessment of pachychor- oid and other retinal-choroidal diseases. Cheng Si