Image analysis of optical coherence tomography scans to explore established and novel choroidal features in patients with central serous chorioretinopathy.

PURPOSE To explore the characteristics of choroidal tissue in patients with and without central serous chorioretinopathy (CSC) using an automated system of image analysis to determine known and novel metrics. METHODS This was a retrospective case-control analysis of optical coherence tomography (OCT) scans of patients seen at Manchester Royal Eye Hospital, UK, comparing patients with active CSC to an age and gender-matched group with no CSC using a purpose-built automated system of image analysis. The expert system segments and measures established and novel features of choroid using a combination of thresholding, noise removal and morphological techniques. RESULTS A total of 72 patients were included in this study, with 40 included in the group with CSC and 32 patient controls with no CSC. There were significant increases from normal to CSC of median choroidal vascular index, 54.7(Median absolute deviation=9.8) to 61.2(4.3) and all choroidal thickness indices including maximum depth, from 249.0(90.1) µm to 372.3(80.3) µm. For novel measures there was a significant increase in tissue entropy from 6.68(0.28) to 6.95(0.17) and area of the largest five vessels from 6.28(3.04) mm2 to 9.10(3.49) mm2. The ratio of vessel lumen to stromal tissue intensity was conversely significantly reduced from 0.674(0.11) in normal patients to 0.59(0.06) in CSC. CONCLUSIONS The automated system of choroidal analysis expands on the utility of known measures and introduces novel metrics. These findings contribute pathophysiological insights and metrics for further assessment and research on conditions affecting choroidal tissue.