Quantitative analysis of conjunctival microvasculature imaged using optical coherence tomography angiography

摘要

Background:The goal was to quantitatively analyze the bulbar conjunctival microvascular density using optical coherence tomography angiography (OCTA) and compare it to the vessel density using functional slit-lamp biomicroscopy (FSLB).Methods:Temporal bulbar conjunctiva of 20 eyes (10 healthy subjects) was imaged using both OCTA and FSLB.Image processingwas performed including equalization,de-noising,thresholding,and skeletonization.The vessel density was measured by fractal analysis (box counting,Dbox) and pixel counting (％).Results:Vessel density (Dbox) of the bulbar conjunctiva obtained using OCTA was 1.28 ± 0.01 Dbox,which was significantly lower than the result (1.32 ± 0.01 Dbox,P ＜ 0.001) obtained using FSLB.Furthermore,the vessel density (％) obtained using OCTA was 3.31 ± 0.12％,which was also significantly lower than the result (3.69 ± 0.16％,P ＜ 0.001) obtained using FSLB.No significant correlations (r ranged from 0.21 to 0.32,P ＞ 0.05) between both instruments were found in both vessel density methods (Dbox and percentage).However,in each of the devices,vessel density in Dbox was significantly correlated with the vessel density in percentage (r=1.0 for FSLB and r=0.98 for OCTA,both P ＜ 0.001).Conclusion:This study demonstrated that the vessel density of the bulbar conjunctiva obtained using OCTA can be quantified,and the results were not compatible with that obtained using slit-lamp biomicroscopy photography.