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Time-frequency analysis of spontaneous fluctuation of the pupil size of the human eye

100%

Nowak W. , Hachoł A. , Kasprzak H.

Optica Applicata

2008

tom Vol. 38, nr 2

469-480

The aim of this work has been to develop a new method of variability description for the spontaneous pupillary fluctuation (SPF) signal, based on the time-frequency analysis. In the work we have studied the variability of the SPF signal spectrum. Based on the PSS (Kwiatkowski, Philips, Schmidt, Shin) test, it has been shown that the SPF signal is non-stationary. A method of SPF signal variability analysis has been proposed using the STFT in the time- frequency domain, and then quantitative variability measures have been introduced to the obtained spectrograms. The application of fast pupillometry for recording the SPF allowed to expand the analyzed frequency band to 20 Hz. The proposed method of analysis and introduced measures of SPF variability enable the detection and quantitative description of short-lasting time-frequency and time-amplitude variations that remain obscured by the overall spectral analysis. SPF signal analysis methods and exemplary results obtained with the methods are presented in the paper.

Metody i aparatura do badania odruchów źrenicznych

100%

Szczepanowska W. , Kasprzak H. , Hachoł A.

2002

tom nr 4

27-31

System for measurement of the consensual pupil light reflex

100%

Szczepanowska-Nowak W. , Hachoł A. , Kasprzak H.

Optica Applicata

2004

tom Vol. 34, nr 4

619-634

The paper presents the measurement system for quantitative investigation into the consensual reaction of pupil to light. This reaction is called the pupil light reflex (PLR). The system enables the recording and analysis of the time characteristics of pupil radius variation during PLR. In the measurements the stimulating light is projected on the left eye in so-called Maxwellian projection but the consensual reaction (i.e., the change in the radius) of the right eye is recorded. As a detection element the system of two linear CCD sensors has been used. Both the linear and the frequency sensitivity is determined by the technical parameters of the optical system and are respectively 0.05 mm and 90 Hz. Moreover, a special technical arrangement makes the results of measurement independent on the horizontal and vertical movements of head relative to the recording system. This arrangement improves significantly of results. In the paper the examples of PLR time characteristics obtained with the presented measurement system are shown. The influence of the time parameters of the stimulating light on the characteristics shape has been analysed.

Model numeryczny gałki ocznej do korekcji pomiarów ciśnienia wewnątrzgałkowego elektronicznymi tonometrami okulistycznymi

100%

Hachoł A. , Środka W. , Szul E.

tom Vol. 48, nr 2

40-44

Zaprezentowano model numeryczny gałki ocznej przeznaczony do korekcji pomiarów ciśnienia wewnątrzgałkowego elektronicznymi tonometrami okulistycznymi. Geometrię oraz parametry materiałowe zostały dobrane tak, aby uczynić model samonastawnym optycznie. Do budowy modelu numerycznego wykorzystano metodę elementów kończonych (pakiet Cosmos/M oraz oprogramowanie własne). Przedstawiono również wyniki badań symulacyjnych, pokazujące wpływ parametrów materiałów struktur oka, grubości rogówki i jej promienia oraz samego ciśnienia wewnątrzgałkowego na wynik pomiaru.

The paper presents numerical model of the human eyeball which can be used for correction of intraocular pressure measurement using electronic ophthalmic tonometers. Investigated model based on the optical self-adjustment efect of the human eyeball for all value of IOP from the physiological range. The FEA method was used for the construction of the model. The exemplary results showing influence of the eye ball materials parameters, central corneal thicknes, radius of cornea curvature and IOP on the tonometric measurements result (obtained with the described model) have been presented.