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Magdalena Widlicka, D Robert Iskander, Patrycja Krzyzanowska-Berkowska, Malgorzata Kowalska, Visual Optics Group; Spectral analysis of intraocular pressure pulse wave for early prediction of glaucoma. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5640.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the efficacy of spectral analysis of intraocular pressure pulse wave for discriminating healthy eyes from open and close glaucomatous eyes as well as glaucoma suspect eyes.
A prospective study including 262 adults (185 F & 77 M) was set at the Glaucoma Clinic, Department of Ophthalmology, Wroclaw Medical University. Age matched control group (CG) consisted of 62 healthy adults (44 F and 18 M). Patients were classified in 3 groups: diagnosed primary open angle glaucoma patients (129) (POAG), primary angle-closure glaucoma patients (20) (PACG) and glaucoma suspect patients (51) (SG). Subjects underwent ophthalmologic examination including medical history, best corrected visual acuity measurement, slit-lamp biomicroscopy, dilated fundus examination, corneal ultrasound pachymetry, corneal topography, and intraocular pressure measurement with dynamic contour tonometry (DCT, Pascal). Patients with systemic medical history were excluded. The project was approved by the institution’s Ethics Committee and adhered to the Tenets of the Declaration of Helsinki. DCT time series were saved and analyzed with custom written software that included signal preprocessing, filtering and spectral analysis. Unlike previous attempts of analyzing dynamic measurements of ocular pulse (Evans et al, Graefes Arch Clin Exp Ophthalmol, 2002; Bozić et al, Curr Eye Res, 2012), a novel energy content spectral analysis, which takes into account non-stationarity of considered time series, was applied. Spectral content up to the 6th harmonic of the pressure pulse wave was considered. The energy ratio of spectral bins located around the 6th and 1th harmonic was chosen as a discriminating parameter. Statistical analyses included standard descriptive statistics and one-way ANOVA.
The group average energy ratio normalized to that of CG was 23.38, 5.59 and 1.39 for the SG, POAG and PACG, respectively. Significant differences (p<0.05) were found between SG and all other groups, POAG and CG, POAG and PACG but not between CG and PACG.
Spectral analysis techniques that take into account the non-stationary character of the DCT signals could prove to be useful for discriminating/classifying certain types of glaucomatous eyes and for predicting early glaucoma.
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