Choroidal Vascularity Index (CVI) - A Novel Optical Coherence Tomography Parameter for Monitoring Patients with Panuveitis?

Abstract

PurposeTo compute choroidal vascularity index (CVI) using an image binarization tool on enhanced depth imaging (EDI)-optical coherence tomography (OCT) scans as a non-invasive optical tool to monitor progression in panuveitis and to investigate the utility of volumetric data from EDI-OCT scans using custom image analysis software.Materials and MethodsIn this retrospective cohort study, segmented EDI-OCT scans of both eyes in 19 patients with panuveitis were taken at baseline and at 3-month follow-up and were compared with EDI-OCT scans of normal eyes. Subfoveal choroidal area was segmented into luminal (LA) and stromal interstitial area (SA). Choroidal vascularity index (CVI) was defined as the proportion of LA to the total circumscribed subfoveal choroidal area (TCA).ResultsThe mean choroidal thickness was 265.5±100.1μm at baseline and 278.4±102.6μm at 3 months follow up (p = 0.06). There was no statistically significant difference in TCA between study and control eyes (p = 0.08). CVI in the control group was 66.9±1.5% at baseline and 66.4±1.5% at follow up. CVI was 74.1±4.7% at baseline and 69.4±4.8% at 3 months follow up for uveitic eyes (p<0.001). The % change in CVI was 6.2 ±3.8 (4.3 to 8.0) for uveitic eyes, which was significantly higher from % change in CVI for control eyes (0.7±1.1, 0.2 to 1.3, p<0.001).ConclusionThe study reports composite OCT-derived parameters and CVI as a possible novel tool in monitoring progression in panuveitis. CVI may be further validated in larger studies as a novel optical tool to quantify choroidal vascular status.

Comparison of Choroidal Vascularity Markers on Optical Coherence Tomography Using Two-Image Binarization Techniques

“…CVI but not CT, was shown to be independent from systemic and ocular factors such as age, axial length, intraocular pressure, or systolic blood pressure in a large study involving 345 normal subjects. 20 In eyes from diabetic patients and eyes with exudative AMD, there were decreased CVI with no significant change in CT. 26,28,29 CVI was also shown to provide additional information to CT in terms of longitudinal choroidal structural changes in diseases such as panuveitis 20 ; Vogt-Koyanagi-Harada (VKH) disease 25 ; central serous chorioretinopathy (CSCR) 24 ; and myopic choroidal neovascularization. 27 Changes in L/C ratio or a similar index called L/S ratio (ratio of choroidal luminal area to stromal area) were investigated and found to yield valuable information in normal physiologic conditions including diurnal variation 22 and dynamic exercise 23 as well as in a number of ocular diseases including exudative AMD 21 ; polypoidal choroidal vasculopathy (PCV) 34 ; CSCR 32,33 ; VKH disease 30,31 ; and retinitis pigmentosa.…”

“…18,19 This has led to the creation of a novel structural marker for choroidal vascularity, which is the ratio of vascular (or luminal) area to total choroidal area. It was termed ''choroidal vascularity index (CVI)'' by Agrawal et al 19 or ''luminal/choroidal area ratio (L/C ratio)'' by Sonoda et al 18 This new marker of choroidal vascularity has been investigated in normal physiologic conditions 18,[20][21][22][23] and also validated as a useful tool in various ocular diseases. 19,[24][25][26][27][28][29][30][31][32][33][34][35][36] Differences exist in the image binarization algorithms for the calculation of CVI and L/C ratio.…”

“…19,[24][25][26][27][28][29][30][31][32][33][34][35][36] Differences exist in the image binarization algorithms for the calculation of CVI and L/C ratio. 20 Although they are measuring the same entity, there is no direct head-to-head comparison between the two. There is also no gold standard that they can be compared against.…”

Optical coherence tomography and optical coherence tomography angiography in uveitis: A review

“…Vitreous haze has been reliably measured on posterior segment OCT scans . In addition, new parameters such as the choroidal vascularity index (the ratio between vessel lumina and the total choroidal area) or the vessel density measured by OCTA have been proposed as adjunctive tools to objectively evaluate the inflammatory status of uveitic eyes.…”

Choroidal structural analysis and vascularity index in retinal dystrophies

“…Recently choroidal vascularity index (CVI) was proposed as a novel OCT‐based choroidal vascularity marker (Agrawal et al. ,d). In this study, we envisage to compare choroidal structural changes measured by CVI in eyes with retinal dystrophies with healthy controls and to determine the correlation between CVI and demographic/clinical factors including age, gender, visual acuity, diagnoses and duration of symptoms.…”