PRZEGLĄD ELEKTROTECHNICZNY, ISSN 0033-2097, R. 92 NR 8/2016 105 Vladimir FIRAGO 1 , Alexey KUBARKO 2 , Oleksandra HOTRA 3 , Irina VOLKOVA 1 , Ainur KOZBAKOVA 4 , Nazarbek MUSABEKOV 4 Belarusian State University (1), Belarussian State Medical University (2), Lublin University of Technology (3), Kazakh National Research Technical University after K.I. Satpayev (4) doi:10.15199/48.2016.08.29 Determination of blood flow velocity in vessels of the bulbar conjunctiva Abstract. The paper presents the methods and the system for registration of digital video recordings of the sclera with a spatial resolution of 2 µm. The pulsed illumination of the sclera was used to eliminate the image blurring caused by the continuous movement of the eyes. At evaluation of blood flow velocity the stabilization of the position of recorded images relatively to the first image frame is used and the trajectory of displacement of the bulbar conjunctiva of the eye is determined. Streszczenie. W artykule omówiono metody oraz opisano system do rejestracji cyfrowych nagrań wideo twardówki z rozdzielczością przestrzenną 2 µm. Zastosowano impulsowe oświetlenie twardówki w celu eliminacji rozmycia obrazu spowodowanego przez ciągły ruch gałek ocznych. Przy ocenie szybkości przepływu krwi przeprowadza się stabilizację pozycji zarejestrowanych obrazów względem pierwszej ramki obrazu oraz wyznacza się trajektorię przemieszczenia spojówki gałki ocznej. (Wyznaczenie szybkości przepływu krwi w naczyniach spojówki gałki ocznej). Keywords: blood flow velocity, microcirculation, blood vessels of bulbar conjunctiva Słowa kluczowe: prędkość przepływu krwi, mikrokrążenie, naczynia krwionośne spojówki gałki ocznej Introduction Early diagnostics of vessel diseases is based on evaluation of results of various research methods of vessels condition, hemodynamics and functions of different organs and tissues of the body [1]. Vessels of the eye fundus and the bulbar conjunctiva, being the branches of internal carotis artery, are the most accessible for direct observation and evaluation of their condition (Fig. 1). A number of corporations produce fundus cameras to obtain digital images of retinal vessels. It is possible to evaluate the different morphological parameters of retinal vessel network by processing these images [2]. Fundus cameras allow to register only unitary images, as the eye fundus is illuminated by single powerful white light pulse. After its influence, the pupil is narrowed during 200 ms interfering the obtaining of the next images. Only advanced unique laboratory equipment enables us to obtain video recordings of retinal vessels and to estimate the velocity of erythrocytes in retinal capillaries. The vessels of the bulbar conjunctiva covering part of the sclera of the eye and its parts on corneal border are more accessible for research. The network of conjunctival vessels is a part of arterial arches of upper and lower eyelids and anterior ciliary arteries being the branches of ophthalmic artery extending from internal carotid artery. The branches of arterial and venous conjunctival vessels form the microcirculation vessel network which basic part lies in deeper layers, the smaller part lies in superficial layers of bulbar conjunctiva (Fig. 1). The main parameters describing the blood microcirculation in small vessels, are the volume and linear velocity of blood flow. The existing methods of laser Doppler flowmetry give the integrated by scattering volume distribution of velocity projections. It does not allow to evaluate the blood flow velocity in certain vessels and capillaries. The known laser methods of blood flow velocity measurement in capillaries and small vessels [3, 4] are difficult in realization and do not find wide application in clinical practice. The conjunctiva vessels are available for direct videorecording. The apparatus and the method for determining the blood flow velocity in these vessels are described in [5]. The apparatus include the expensive fast speed video camera (250 frames/s). The obtained frames are recorded in hard disk. As the eye is continuously moving, the stabilization of the position of the obtained images based on the SURF method is used. Then the required area of the vasculature is chosen and the velocity of blood formed elements is determined using the shift of the blood formed elements during n frames. The drawback of this method is the large amount of data, which should be processed for determination of v b . Fig.1. Scheme of conjunctival vasculature: 1 – anterior ciliary artery; 2 – episcleral arteries; 3 – episcleral venous network; 4 – lymphatic vessels of conjunctiva The paper discusses the method and the technique for obtaining the digital images of conjunctiva vessels using the pulse sclera illumination, that allows to reduce the volume of the recorded and processed data in tens times. Methods for obtaining and recording the images In order to reduce the number of video recordings of scleral vessels the pulsed illumination of the observed region of the sclera can be used. During recording the patient must fix the eyes on a bright enough point to eliminate the influence of saccadic eye movements. Then at pulse duration of 1 ms the shift of the sclera and the formed elements of blood will not exceed 1 m. The spatial resolution of videorecording should be chosen no less than 2 m. The modulation of the intensity of eye illumination using LEDs is the most simple to realize. The brightness of the 1 2 3 4