Model based investigation of retinal vessel tortuosity as a function of blood pressure: preliminary results.

Tortuosity is one of parameters which describe a state of the eye fundus blood vessels. Tortuosity can be estimated from the detected vessels in optical fundus images. The increase in vessel tortuosity was observed in eyes of patients with advanced background diabetic retinopathy, papilloedema, even in some completely healthy eyes (in this case tortuosity does not change in time). Though many methods to estimate eye vessel tortuosity exist, dependencies between tortuosity and parameters of cardiovascular system are not fully explored. In this paper we studied whether different tortuosity estimation algorithms can detect the change of blood pressure in the cylindrical segment of the vessel modeled using finite elements method. In addition we studied how does one inhomogenity added inside the blood vessel influence the tortuosity and what are the relationships between the different tortuosity estimates and blood pressure? We found that even single inhomogenity of the vessel wall triggers the increase of tortuosity when inner blood pressure increases. The resulting dependencies among different tortuosity estimates and blood pressure are mostly nonlinear.