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. 2017 Nov 22;11:2073–2089. doi: 10.2147/OPTH.S140110

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© 2017 Guha Mazumder et al. This work is published and licensed by Dove Medical Press Limited

The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License (http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed.

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Mean FTIR spectra of the whole region (400–4,000 cm⁻¹).

Notes: (A) Mean spectra of the fingerprint region (900–1,800 cm⁻¹) after RBBC; (B) mean spectra of the region between 400 and 1,200 cm^–1 after RBBC, maximum vector normalization, followed by Savitzky–Golay differentiation of the first derivative spectra of NOM, DM, and DR; (C) LDA score plot of preprocessed spectra after mean centering and (D) PCA–LDA with confidence ellipse representing confidence interval at 95%. Mean spectra of the whole region for all conditions: (E) NOM, (F) DM, and (G) DR.

Abbreviations: au, arbitrary unit; DM, diabetes mellitus; DR, diabetic retinopathy; FTIR, Fourier transform infrared; LDA, linear discriminant analysis; LD1, linear discriminant 1; LD2, linear discriminant 2; NOM, normal; PCA, principal component analysis; RBBC, rubber band-like baseline correction.

Mean FTIR spectra of the whole region (400–4,000 cm⁻¹).

Notes: (A) Mean spectra of the fingerprint region (900–1,800 cm⁻¹) after RBBC; (B) mean spectra of the region between 400 and 1,200 cm^–1 after RBBC, maximum vector normalization, followed by Savitzky–Golay differentiation of the first derivative spectra of NOM, DM, and DR; (C) LDA score plot of preprocessed spectra after mean centering and (D) PCA–LDA with confidence ellipse representing confidence interval at 95%. Mean spectra of the whole region for all conditions: (E) NOM, (F) DM, and (G) DR.

Abbreviations: au, arbitrary unit; DM, diabetes mellitus; DR, diabetic retinopathy; FTIR, Fourier transform infrared; LDA, linear discriminant analysis; LD1, linear discriminant 1; LD2, linear discriminant 2; NOM, normal; PCA, principal component analysis; RBBC, rubber band-like baseline correction.