Fourier-Transform Infrared Spectroscopy of Epiretinal Membranes and Internal Limiting Membranes after Pars Plana Vitrectomy with Membrane Peeling

Abstract

Introduction: Fourier-transform infrared imaging (FTIRI) enables examination of protein secondary structure in the analyzed tissues. The aim of our study was to examine the distribution of secondary structures in epiretinal membranes (ERMs) and internal limiting membranes (ILMs), and to explore possible associations to other diagnostic variables. Methods: This prospective pilot study included patients scheduled for pars plana vitrectomy with membrane peeling. ERMs and ILMs were harvested during surgery and placed on a BaF₂ window for postsurgical FTIRI analysis. Infrared hyperspectral images were subjected to second and fourth derivative analysis to obtain information of the protein secondary structures present in the tissues. Results: Samples of 43 patients were analyzed, with the triple helical domain showing the highest prevalence in the examined tissues. The other secondary structures (beta-sheet, random coil, and beta-turn) showed a heterogenous distribution in the examined samples, without specific associations to indication of surgery, comorbidities, outcomes from optical coherence tomography, and intrasurgical findings. Conclusions: FTIRI enables analysis of the spatial distribution of protein secondary structures in the examined tissues; thus, it is a useful analytical technique for the analysis of ERMs and ILMs.