[Experimental simulation for determining optimal design parameters of a transpalpebral tonometry sensor]. / Éksperimental'noe modelirovanie kak osnova opredeleniia optimal'nykh parametrov datchika dlia transpal'pebral'noi tonometrii.

PURPOSE: To determine optimal design parameters of a transpalpebral tonometry sensor (the weight and diameter of the rod) based on experimental simulation. MATERIAL AND METHODS: The study has been conducted in situ at the forensic analysis department with 12 eyes of 5 men and one woman aged 49 to 71 years. Comparison between the tonometric pressure and the true pressure measured with direct manometric technique ensured the accuracy of transpalpebral tonometry data and helped select optimal sensor parameters. For this purpose, an experimental assembly was designed and produced, comprised of a testing stand with a system of tubes filled with distilled water, an indicating pressure gauge calibrated by the height of the water column, a millimeter scale on a holder, as well as a needle with connecting tubes and two valves. RESULTS: No statistically significant differences between the tonometric and manometric level of pressure in the eye were observed when using a sensor weighing 16 g with rod diameter of 1.5 or 3 mm. Only an insignificant dependence of the tonometry data on the thickness of the eyelid was noted at high levels of intraocular pressure (IOP). CONCLUSION: The experimental study conducted on the developed assembly has allowed us to substantiate the choice of optimal design parameter for a transpalpebral IOP measurement sensor. A transpalpebral tonometer with such sensor characteristics can be recommended for comparative clinical study, as well as for determination of its effectiveness in dynamical monitoring of the IOP levels.

[Transpalpebral Tetrapolar Reoophtalmography in the Assessment of Parameters of the Eye Blood Circulatory System].

BACKGROUND: Quantitative assessment of hemodynamic parameters is an important element of ophthalmic diagnostics especially in early detection of myopia, glaucoma, diabetic retinopathy. The assessment of hemodynamic changes is essential in evaluating of the efficiency of treatment. Objective: Our aim was to determine the adequate of eye hemodynamics assessment using reoophtalmography in patients with various clinical refractions. METHODS: A controlled study was carried out. All tests were performed using transpalpebral tetrapolar method. Signal registration lasted for 20 seconds in the supine position, and then the diagnostic parameters were calculated. RESULTS: We present the results of examination of 76 patients aged 5 to 22 years (average age 13.0 ± 1.1). 32 patients had low myopia (62 reoophtalmography records), 23 patients had moderate myopia (42 records) and 5 patients had high myopia (12 records). The control group was composed of 16 patients. The main differences were found in the rheographic index, which is equal to 58.1 ± 4.1 mOhm in the control group. It is significantly reducing with refraction increase, from 47.8 ± 3.2 mOhm in low myopia to 34.0 ± 2.5 mOhm in high myopia (p = 0.050). This is an evidence of blood supply deficiency in the myopic eyes. CONCLUSION: Rheographic index was shown to differ in different breathing phases, which agrees with the known physiological regularities. The proposed method is highly informative and sufficiently accurate what allows assessing the eye blood supply state objectively. It is easy to apply and requires no contact with the eye surface, which is especially important in pediatric practice.