diagnostics Article Comparison between Widefield Optical Coherence Tomography Devices in Eyes with High Myopia Federico Corvi 1,2,3, * , Federico Zicarelli 1,† , Matteo Airaldi 1 , Salvatore Parrulli 1 , Mariano Cozzi 1 , Davide Monteduro 1 , Francesco Romano 1 , SriniVas R. Sadda 2,3 and Giovanni Staurenghi 1   Citation: Corvi, F.; Zicarelli, F.; Airaldi, M.; Parrulli, S.; Cozzi, M.; Monteduro, D.; Romano, F.; Sadda, S.R.; Staurenghi, G. Comparison between Widefield Optical Coherence Tomography Devices in Eyes with High Myopia. Diagnostics 2021, 11, 658. https://doi.org/10.3390/ diagnostics11040658 Academic Editor: Daniele Tognetto Received: 7 March 2021 Accepted: 4 April 2021 Published: 6 April 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Eye Clinic, Department of Biomedical and Clinical Science “Luigi Sacco”, Sacco Hospital, University of Milan, via G.B Grassi 74, 20157 Milan, Italy; federicozicarelli@gmail.com (F.Z.); matteo.airaldi@unimi.it (M.A.); salva.parru90@gmail.com (S.P.); mariano.cozzi88@gmail.com (M.C.); davidemonteduro5@gmail.com (D.M.); francesco.romano@unimi.it (F.R.); giovanni.staurenghi@unimi.it (G.S.) 2 Doheny Eye Institute, University of California at Los Angeles, Los Angeles, CA 90095, USA; ssadda@doheny.org 3 Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA * Correspondence: federico.corvi@yahoo.it; Tel.: +39-02-3904-2441; Fax: +39-02-3904-2443 † These authors have contributed equally to this work. Abstract: Background: To compare four different optical coherence tomography (OCT) devices for visualization of retinal and subretinal layers in highly myopic eyes. Methods: In this prospective, observational, cross-sectional study, consecutive patients with high myopia and control subjects were imaged by four OCT devices: Spectralis OCT2, PlexElite 2.0 100 kHz, PlexElite 2.0 200 kHz and the Canon Xephilio OCT-S1. The acquisition protocol for comparison consisted of single vertical and horizontal line scans centered on the fovea. Comparison between the devices in the extent of visible retina, presence of conjugate image or mirror artifacts, visibility of the sclerochoroidal interface and retrobulbar tissue. Results: 30 eyes with high myopia and 30 control subjects were analyzed. The visualized RPE length was significantly different between the OCT devices with Xephilio OCT-S1 imaging the largest extent (p < 0.0001). The proportion of eyes with conjugate image artifact was significantly higher with the Spectralis OCT (p < 0.0001), and lower with the PlexElite 200 kHz (p < 0.0001). No difference in visibility of the sclerochoroidal interface was noted among instruments. The retrobulbar tissue was visible in a higher proportion of eyes using swept-source PlexElite 100 kHz and 200 kHz (p < 0.007) compared to the other devices. Conclusions: In highly myopic eyes, the four OCT devices demonstrated significant differences in the extent of the retina imaged, in the prevalence of conjugate image artifact, and in the visualization of the retrobulbar tissue. Keywords: conjugate image artifact; high myopia; myopia; optical coherence tomography; retina; retrobulbar tissue; sclerochoroidal interface 1. Introduction Myopia is one of the most common eye problems, and is growing, affecting 1.6 billion individuals worldwide [1]. It has been estimated that the prevalence of myopia and high myopia will increase to 5 billion people and 1 billion people, respectively, by 2050 [1]. Myopia is currently defined by a spherical equivalent of ≤-0.50 diopters or an axial length (AL) > 24.5 mm, while high myopia as a spherical equivalent of ≤-6.00 diopters or an AL of ≥ 26.5 mm [2]. The increase in AL and associated ectasia may lead to structural and functional degenerative changes characteristic of pathologic myopia [3–5]. Advances in imaging technologies such as optical coherence tomography (OCT) and three-dimensional magnetic resonance imaging (MRI) have enhanced our understanding of the ocular changes associ- ated with high myopia [3,6]. In fact, the two key factors in the development of pathologic myopia are the elongation of the AL and posterior staphyloma [4]. However, the increase Diagnostics 2021, 11, 658. https://doi.org/10.3390/diagnostics11040658 https://www.mdpi.com/journal/diagnostics