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

Abstract

<b><i>Introduction:</i></b> 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. <b><i>Methods:</i></b> 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 BaF<sub>2</sub> 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. <b><i>Results:</i></b> 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. <b><i>Conclusions:</i></b> 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.

Diagnostische Reliabilität von optischen Kohärenztomografie-Biomarkern für postoperativen Erfolg bei idiopathischen epiretinalen Membranen

“…Für diese retrospektive Analyse wurden Patientinnen und Patienten eingeschlossen, bei denen eine Pars-plana-Vitrektomie mit Membrane Peeling aufgrund von iERM an der Augenabteilung des Hanusch-Krankenhauses Wien, Österreich, durchgeführt wurde im Zeitraum zwischen Mai 2014 und August 2019. Die Patientinnen und Patienten wurden aus 6 prospektiven Studien ausgewählt 9 , 24 , 25 , 26 , 27 , 28 und in die Analyse inkludiert, wenn sie folgende Einschlusskriterien erfüllt haben: a) Vorhandensein einer iERM, b) Indikation für das Membrane Peeling – diese wurde durch einen signifikanten Visusabfall und/oder Metamorphopsien durch die iERM definiert, und c) pseudophaker Linsenstatus zum Zeitpunkt 3 Monate postoperativ. Patientinnen und Patienten mit Makulaödem, das durch andere Augenerkrankungen als iERM verursacht wurde, wurden von der Studie ausgeschlossen.…”

“…This retrospective analysis included patients scheduled for pars plana vitrectomy with membrane peeling for an iERM between May 2014 and August 2019 at the Department of Ophthalmology at the Hanusch Hospital in Vienna, Austria. Patients were selected from six prospective studies 9 , 24 , 25 , 26 , 27 , 28 and included for analysis in cases where they fulfilled the following inclusion criteria: a) presence of an iERM, b) indication for membrane peeling, defined as a significant loss of visual acuity and/or metamorphopsia due to the iERM, and c) pseudophakia at the final visit at 3 months after surgery. Patients with macular edema caused by conditions other than an iERM were excluded from the study.…”