Observing micro-vessels in conjunctiva could be used not only for diagnosing conjunctival diseases including conjunctivitis and pterygium but also as biomarkers for circulatory diseases. Many research teams have developed compact imaging and auto-analysis systems to simplify the conventional slit lamp as well as enhance the analysis process. The imaging system, previously developed by our research team, corrects eye motion in imaging windows through image registration and template matching. The developed system quantifies blood flow velocity using the sequence of motion-corrected images. This study compares estimated flow velocity and the fluid's actual velocity using the experimental phantom comprising transparent hoses and fluid including beads corresponding to red blood cells. The flow velocities are calculated using the Hagen-Poiseuille equation, and the flow rates generated by the syringe pump. The pump applies three kinds of flow rates to generate flow velocity variations and the estimated velocities are linearly proportional to these variations. In addition, the phantom has a random motion to mimic the fixational eye movements within the range of the healthy subject's angular eye motion. Through these experiments, we verified the previously developed flow velocity measurement system having percent errors under 3% by comparing estimated flow velocities with actual flow velocities. The system's accuracy, especially under conditions without artificial motion, is over 98.5%. These experiments can provide the supporting background for feasibility and accuracy in a further clinical study in conjunctival microcirculation.
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