Rheoophthalmography Used for the Analysis of Blood Flow in the

Posterior Part of the Eye

P. V. Luzhnov

, A. A. Kiseleva

, E. N. Iomdina

, L. V. Vasilenkova

and O. A. Kiseleva

Bauman Moscow State Technical University, 5, 2-nd Baumanskaya St., Moscow, Russian Federation

Hemlholtz National Medical Research Center of Eye Diseases, 14/19, Sadovaya-Chernogryazskaya St.,

Moscow, Russian Federation

Keywords: Rheoophthalmography, Ocular Blood Flow, Primary Open-angle Glaucoma.

Abstract: The paper is aimed at developing a new rheoophthalmography (ROG) technique able to measure electrical

impedance signals of patients with primary open-angle glaucoma (POAG), which could facilitate early

diagnostics of the disease and the differentiation of its stages. We used a technique of electrode positioning

differing from the transpalpebral ROG technique used previously. Specifically, we changed the distance

between the measuring electrodes and their location pattern: the axis of symmetry was rotated 90° relative to

that used in the transpalpebral technique and located vertically rather than horizontally. This technique was

applied to ROG signals of 32 patients (42 eyes) aged 67.7 years averagely. Of these, 6 patients (10 eyes)

average aged 62.7 years had stage I (early) POAG or suspected POAG; 13 patients (17 eyes) average aged

69.4 years had stage II (developed) POAG; 10 patients (12 eyes) average aged 70.0 years had stage III

(advanced) POAG; 3 patients (3 eyes) average aged 69.3 years had stage IV (terminal) POAG. The results of

this study confirmed the feasibility of the above technique for ROG signal registration. The recorded signals

are informative for quantitative assessment of blood flow in the posterior part of the eye, which enables early

POAG diagnostics and differentiation between POAG stages.

1 INTRODUCTION

The normal functioning of the eye is essentially

determined by the blood flow level in its tissues. For

ocular pathologies such as progressive myopia,

diabetic retinopathy, and glaucoma, eye

hemodynamic examination provides the

ophthalmologist with additional information about

their pathogenesis, gives the opportunity for early

diagnosis, prognostication of the disease

development, and assessment of treatment

effectiveness. The research in this area is important

due to the growing incidence of these ophthalmic

diseases.

The electrical impedance technique allows non-

invasive assessment of blood flow in diverse

segments of the human body (Patterson, 2005; Bodo,

2010; Lazarenko, 2004). It extracts information about

the pulsatile blood supply of the studied segment.

Furthermore, electrical impedance provides

information about the biomechanical properties of

https://orcid.org/0000-0003-1111-7063

blood vessels. As far as eye electrical impedance is

concerned, a special technique, called

rheoophthalmography (ROG), was developed

(Avetisov, 1967; Lazarenko, 1999; Lazarenko, 2004).

The authors of subsequent research in the field,

including those of the present study (Luzhnov et al,

2015; Luzhnov et al., 2017) described one of the

varieties of ROG, the transpalpebral

rheoophthalmography (TP ROG), in which the

electrodes are superimposed on a closed eyelid. The

results of mathematical modeling were used as part of

the development of this technique, taking into

account the anatomical structure of the vascular bed

of the eyeball (Shamaev, 2017; Shamaev, 2018). Eye

blood flow during the development of myopia was

studied, which showed the applicability of this

technique forearly diagnosis of myopia progression in

children (Iomdina, 2014; Luzhnov, 2015). It should

be emphasised that low and moderate myopia affects

most of all the blood flow of the anterior eyeball

structures.

Luzhnov, P., Kiseleva, A., Iomdina, E., Vasilenkova, L. and Kiseleva, O.

Rheoophthalmography Used for the Analysis of Blood Flow in the Posterior Part of the Eye.

DOI: 10.5220/0009165902630267

In Proceedings of the 13th International Joint Conference on Biomedical Engineering Systems and Technologies (BIOSTEC 2020) - Volume 1: BIODEVICES, pages 263-267

ISBN: 978-989-758-398-8; ISSN: 2184-4305

263

In the case of primary open-angle glaucoma

(POAG), even in its early stages, changes of blood

flow are observed in all parts of the eye

(Cherecheanu, 2013). As is well known, this disease

is one of the leading causes of blindness (Quigley,

2006). Currently, the pathogenesis of POAG is

mostly associated with increased individual level of

intraocular pressure (IOP). Increased IOP damages

the optic nerve fibers and cells of the retina, which

gradually leads to an irreversible loss of vision.

However, not only an into lerable IOP level but also

other factors can lead to the development and

progression of POAG. One of the risk factors of

progressive visual impairment due this disease is a

decrease in the blood supply level in the vessels of the

brain and the eye (Schmetterer, 2015). Eye

hemodynamics monitoring in POAG patients may

give useful diagnostic information for glaucoma

clinicians.

A number of studies, described in (Luzhnov,

2018), were carried out on the analysis of TP ROG

signals in patients with POAG. It was shown that the

estimation of amplitude parameters became more

informative if waveform analysis is used. So, the

analysis of electrical impedance signals in POAG

must include a qualitative and quantitative estimation.

A qualitative analysis of signals includes determining

the type of the pulse wave. It is affected by

biophysical, biomechanical and hydrodynamic

factors, which subsequently determine the diagnostic

result in the qualitative analysis of signals. At the

moment, the analysis of the pulse wave shape in TP

ROG is carried out using attractors (Luzhnov, 2018).

This analysis allows indirect evaluation of blood flow

in different parts of the eye, as well as their interaction

with each other. On the whole, however, the issue of

quantitative determination of blood flow indices in all

(not only the anterior) parts of the eye using non-

invasive electrical impedance methods remains

unresolved. It is especially vital for early diagnosis of

POAG and differentiation of the POAG stages.

The aim of this work, therefore, is to develop the

ROG technique, which could ensure quantitative

analysis of electrical impedance signals of the

posterior part of the eye in patients with POAG,

including the possibility of early diagnosis of the

disease and differentiation between its stages.

2 MATERIALS AND METHODS

Currently, various methods are used to study the

blood supply of eye structures (Kurysheva, 2017).

The electrical impedance diagnostic method allows a

comprehensive assessment of blood flow state in the

eye vessels as a whole, in contrast to research

methods that determine the blood supply of each

vessel individually. The technique of TP ROG

involves a quantitative assessment of blood supply at

the depth of sounding corresponding to the anterior

part of the eye (Luzhnov, 2015). Therefore, a new

technique for applying electrodes for the assessment

of posterior eye pole hemodynamic parameters of

POAG patients was used in the present work.

To reach the posterior eye pole vascular bed

(Roebuck, 2015), the estimated sounding depth

should be increased. Accordingly, we used increased

distance between the ROG measuring electrodes, and

their location was changed: the axis of symmetry was

rotated 90° relative to that used in the previous ROG

technique and was located vertically rather than

horizontally (see Fig.1).

The vertical orientation with the arrangement of

four electrodes (a pair of current electrodes and a pair

of measuring ones) in the tetrapolar system of leads

allowed us to provide the desired interelectrode

distance during its superimposition. The distance

between the electrodes was controlled by a rigid

fastening system, made similarly to the method

described in (Kiseleva, 2020).

To register the TP ROG signal, a semi-rigid

substrate was used for attaching the electrodes. A pair

of measuring electrodes was located at a distance of

13 mm from each other. This enables measuring the

blood flow at a distance corresponding to the anterior

part of the eye. To register the ROG PP signal, we use

an ABS plastic plate with holes for electrodes. A pair

of ROG PP measuring electrodes is spaced 60 mm

apart. Thanks to this arrangement we are able to

measure blood flow at the depth corresponding to the

posterior pole of the eye. Such system parameters

enable the registration of an electrical impedance

signal produced by blood supply of both the posterior

and the anterior part of the eye.

The distance between the round electrodes was

considered the distance between their centres, or

attachment points. In preliminary studies, the selected

methods of applying electrodes to adult patients and

children aged 8 years or older were tested. The

accuracy of positioning and the quality of electrode

placement made it possible to register ROG signals

for subsequent analysis of ocular blood flow.

To register the signals, an impedance measuring

transducer with a probe current frequency of 100 kHz

was used. The signal analysis of the ROG pulse blood

supply was carried out after filtering the obtained

electrical impedance signal with a Butterworth

fourth-order band-pass filter with a lower cut-off

BIODEVICES 2020 - 13th International Conference on Biomedical Electronics and Devices

264

Figure 1: The location of two tetrapolar electrodes systems:

transpalpebral for anterior part of the eye (TP ROG) and

rotated for posterior part of the eye (ROG PP).

frequency of 0.15 Hz and an upper cut-off frequency

of 100 Hz. The signal was recorded for 20 seconds.

The amplitude of the ROG signal was determined as

the arithmetic mean of the amplitudes of all pulse

waves included in the 20-second recording period. A

frequency band below 0.15 Hz determined the level

of blood flow by the amplitude of the base impedance

signal. To achieve this, the initial signal was filtered

with a second-order Chebyshev filter. As a result,

when analysing the ROG signals, two indicators were

calculated: the amplitude of the pulse wave, or the

rheographic index (RI), and the value of the base

impedance (BI). An example of electrical impedance

signal registration for the posterior part of the eye

(ROG PP) is shown in Fig.2.

Figure 2: An example of ROG PP signal in a patient with

stage I POAG.

The study was conducted in the glaucoma

department of the Hemlholtz National Medical

Research Center of Eye Diseases. In total, ROG PP

signals of 32 patients (42 eyes) averagely aged 67.7

years were analysed. Of these, 6 patients (10 eyes,

average age 62.7 years) had stage I (early) POAG or

suspected POAG; 13 patients (17 eyes, average age

69.4 years) had stage II (developed) POAG; 10

patients (12 eyes, average age 70.0 years) had stage

III (advanced) POAG; 3 patients (3 eyes, average age

69.3 years) had stage IV (terminal) POAG.

This study was performed in accordance with the

Declaration of Helsinki and was approved by the

Local Committee of Biomedical Ethics of the

Moscow Hemlholtz National Medical Research

Center of Eye Diseases. A written informed consent

was obtained from all participants.

3 RESULTS

It was found that in the examined groups of patients,

the average value of the RI indicator increases with

the severity of the disease (from stage I to III, see

Table 1). In stage IV, the average RI indicator fell

slightly. An increase was also established in the

average value of the BI indicator with POAG

progression from stage I to stages II and III. The

increase was even more significant at stage IV of the

disease.

The increase of BI indicator reflects a drop in the

total blood supply in eye tissues. Our study showed

two characteristic changes of this indicator. The first

was observed when POAG progressed from stage I to

more advanced stages whilst the second change took

place with the onset of stage IV POAG.

Rheoophthalmography Used for the Analysis of Blood Flow in the Posterior Part of the Eye

265

Table 1: RI and BI indicators in the examined groups

(M±SD).

Stage of POAG RI, Ohm BI, Ohm

I 0.11±0.02 46.1±9.7

II 0.13±0.03 52.7±10.4

III 0.14±0.03 51.2±10.9

IV 0.10±0.04 57.3±10.3

In addition to averaging the diagnostic indices by

study groups, they were also compared for patients

with different stages of POAG in the right and the left

eye. In total, ROG PP signals of five patients were

analysed; five pairs of ROG records were examined.

In this case, similar proportions were observed but the

values were higher. For example, the RI of the eye

after antiglaucoma surgery and the non-operated eye

of the same patient was approximately 2.6 times

different.

4 CONCLUSIONS

The results obtained in the study confirm the

feasibility of the method of applying electrodes

proposed in the work for ROG signals registration.

The signals recorded in such a way are informative

for hemodynamics assessment in POAG patients,

which can be used for early diagnostics of POAG and

differentiation between its stages. The difference in

hemodynamic parameters observed between the

fellow eyes with different POAG stages of the same

patient confirms the efficiency of the new technique.

As a further development of this work, the authors

consider a joint study of ROG signals recorded

simultaneously using different leads, which will

allow us to differentiate the changes in the level of

blood flow depending on the depth of sounding, and,

consequently, on the part of the eye.

When using a device in which the ROG signal is

recorded transpalpebrally through one channel with a

tetrapolar lead system installed on the eyelid, and

through a second channel with a tetrapolar lead

system installed symmetrically with respect to the

anteroposterior axis of the eye on the face in the area

of the eye socket, it becomes possible to expand the

existing facilities of the electric impedance

diagnostics of the ocular blood flow.

A simultaneous analysis of electrical impedance

signals through two channels, TP ROG and ROG PP,

makes it possible to estimate the level of blood flow

in the anterior part of the eye by the signal of the first

channel and in the posterior part of the eye by the

signal received from the second channel.

A research into the relationship between blood

flow in the anterior and posterior parts of the eye at

different stages of glaucoma is also interesting for

understanding the pathophysiological processes of

the development of this disease.

CONFLICT OF INTEREST

The authors declare that they have no conflict of

interest. The paper was supported by a grant from

RFBR (No.18-08-01192).

REFERENCES

Avetisov, E.S., Katsnel'son, L.A., Savitskaia, N.F., 1967.

Rheocyclographic examinations in myopia. Vestnik

Oftal’mologii 80(3): 3–7.

Bodo, M. (2010) Studies in Rheoencephalography. Journal

of Electrical Bioimpedance 1, 18–40.

Cherecheanu A.P., Garhofer G., Schmidl D., Werkmeister

R., Schmetterer L., 2013. Ocular perfusion pressure and

ocular blood flow in glaucoma. Curr Opin Pharmacol

13: 36–42. DOI:10.1016/j.coph.2012. 09.003

Iomdina, E.N., Luzhnov, P.V., Shamaev, D.M., et al., 2014.

An evaluation of transpalpebral rheoophthalmography

as a new method of studying the blood supply to the eye

in myopia. Russian ophthalmological journal 7(4): 20–

24. (in Russian)

Kiseleva, A.A., Luzhnov, P.V., Shamaev, D.M., 2020.

Verification of mathematical model for bioimpedance

diagnostics of the blood flow in cerebral vessels.

Advances in Intelligent Systems and Computing 902:

251–259. DOI: 10.1007/978-3-030-12082-5_23

Kurysheva, N.I., Parshunina, O.A., Shatalova, E.O., et al.,

2017. Value of structural and hemodynamic parameters

for the early detection of primary open-angle glaucoma.

Curr. Eye Res. 42(3): 411–417.

Lazarenko, V.I., Komarovskikh, E.N., 2004. Results of the

examination of hemodynamics of the eye and brain in

patients with primary open-angle glaucoma. Vestnik

oftalmologii 120(1): 32–36. DOI:10.21687/0233-

528X-2017-51-3-22-30

Lazarenko, V.I., Kornilovsky, I.M., Ilenkov, S.S. et al.,

1999. Our method of functional rheography of eye.

Vestnik oftalmologii 115(4): 33–37.

Luzhnov, P.V., Shamaev, D.M., Iomdina, E.N. et al., 2015.

Transpalpebral tetrapolar rheoophtalmography in the

assessment of parameters of the eye blood circulatory

system. Vestn Ross Akad Med Nauk 70(3): 372–377.

DOI: 10.15690/vramn.v70i3.1336

Luzhnov, P.V., Shamaev, D.M., Iomdina, E.N., et al., 2017.

Using quantitative parameters of ocular blood filling

with transpalpebral rheoophthalmography. IFMBE

Proceedings 65: 37–40. DOI:10.1007/978-981-10-

5122-7_10

BIODEVICES 2020 - 13th International Conference on Biomedical Electronics and Devices

266

Luzhnov, P.V., Shamaev, D.M., Kiseleva, A.A., et al.,

2018. Using nonlinear dynamics for signal analysis in

transpalpebral rheoophthalmography. Sovremennye

tehnologii v medicine 10(3): 160–167. DOI:

10.17691/stm2018.10.3.20

Patterson, R. (2005) Electrical Impedance Tomography:

Methods, History, and Applications (Institute of

Physics Medical Physics Series), Physics in Medicine

and Biology 10: 2427–2428.

Quigley, H.A., Broman, A.T., 2006. The number of people

with glaucoma worldwide in 2010 and 2020. Br J

Ophthalmol 90(3): 262–267.

Roebuck, J., 2015. Anatomy 360: The Ultimate Visual

Guide to the Human Body. Thunder Bay Press, San

Diego.

Schmetterer L., 2015. Ocular perfusion abnormalities in

glaucoma. Russian Ophthalmological Journal 4: 100–

109.

Shamaev, D. M., Luzhnov, P. V., Iomdina, E. N., 2018.

Mathematical modeling of ocular pulse blood filling in

rheoophthalmography. IFMBE Proceedings 68(1):

495–498. DOI: 10.1007/978-981-10-9035-6_91

Shamaev, D.M., Luzhnov, P.V., Iomdina, E.N., 2017.

Modeling of ocular and eyelid pulse blood filling in

diagnosing using transpalpebral rheoophthalmography.

IFMBE Proceedings 65: 1000–1003.

DOI:10.1007/978-981-10-5122-7_250

Rheoophthalmography Used for the Analysis of Blood Flow in the Posterior Part of the Eye

267