Mapping diurnal variations in choroidal sublayer perfusion in patients with idiopathic epiretinal membrane: an optical coherence tomography angiography study

Abstract

Background Optical coherence tomography angiography (OCTA) is a non-invasive tool for imaging and quantifying the choroidal vasculature and perfusion state. In this index study, OCTA was used to investigate diurnal changes in choroidal sublayer perfusion in eyes with idiopathic epiretinal membrane (ERM) and to identify impacting factors. Methods A prospective study was conducted on volunteers with symptomatic ERM, each of whom underwent repeated measurements of subfoveal choroidal thickness (SFCT) using enhanced-depth imaging optical coherence tomography and perfusion of choroidal vascular sublayers using OCTA at 7 a.m., 12 p.m., 4 p.m., and 8 p.m. Possible interactions between diurnal variations and other factors, such as gender and age, were evaluated. Results A total of 21 eyes of 21 participants (mean age 72.43 ± 7.06 years) were analysed. A significant pattern of diurnal variation was observed for SFCT ( p = 0.008) as well as perfusion of Haller’s layer (HLP, p = 0.001). SFCT and HLP both demonstrated a quadratic relation to time of the day, decreasing from morning to afternoon, before increasing again in the evening. No significant differences with regard to gender or age were detectable. Conclusion OCTA-based analysis of choroidal sublayer perfusion demonstrated significant diurnal variations in patients with symptomatic ERM, which are quite different from changes reported in healthy eyes. Therefore, it is important to account for time of day, when comparing longitudinal OCTA data.

Evaluating diurnal variations in retinal perfusion using optical coherence tomography angiography

“…Diurnal variations have previously been shown for intraocular pressure (IOP), axial length (AL) and subfoveal choroidal thickness (SFCT) [6,7]. Recently, we demonstrated significant diurnal patterns in choroidal sublayer perfusion in healthy adults and eyes with epiretinal membrane in OCTA-based studies [8,9]. Analyzation of choroidal sublayer perfusion in healthy adults showed significant diurnal variation in Sattler's and Haller's layer perfusion.…”

“…Each en face image was exported into ImageJ (NIH, Version 1.48b, Bethesda, USA) and binarized by the Otsu method, which is an automatic threshold selection from grey-level histograms, to determine the percentage of white and black pixels [15]. Retinal perfusion was calculated by scoring the percentage of white pixels in relation to number of total pixels, according to published protocols [8,9,16].…”

Evaluation of retinal microvascular perfusion in hereditary angioedema: a case-control study

“…It was not necessary to perform manual corrections; the Optovue XR Avanti (Fremont, CA) has active motion-tracking capability to minimize motion artifacts [21]. The OCT-A measurements were performed at the same time of the day (specifically, 3:00-5:00 pm) in both patients and controls [14,[22][23][24]. Thicknesses at the whole image, foveal, and parafoveal zone were measured by OCT [9,10,25].…”

Ocular Blood Flow Changes Impact Visual Acuity Gain after Surgical Treatment for Idiopathic Epiretinal Membrane

“…To avoid artifacts, the retinal vessels were analyzed as full retinal slabs (ILM to retinal pigment epithelium), since subjects with ERM are prone to segmentation errors within the retinal layers ( Figure 1 A) [ 17 ]. The choroidal sublayers were manually segmented to get 20 µm slabs of choriocapillaris (CC) ( Figure 1 B), Sattler’s layer (SL) ( Figure 1 C), and Haller’s layer (HL) ( Figure 1 D) according to previous published protocols [ 8 , 15 , 21 , 22 ]. All acquired en face images were exported into ImageJ (NIH, Version 1.48b, Bethesda, USA) for thresholding.…”

“…Only a few studies have evaluated vascular changes due to ERM formation and ERM removal by using OCTA, focusing especially on retinal microvascular impairment [ 9 , 10 , 11 , 12 , 13 ]. However, the role of the choroid in ERM pathogenesis is not well-known, although recent OCT- and OCTA-based studies suggest choroidal alterations from ERM and following ERM-ILM peeling [ 14 , 15 , 16 ].…”