PurposeTo evaluate the impact of correct anatomical slab segmentation on foveal avascular zone (FAZ) dimensions in the superficial capillary plexus (SCP) and deep capillary plexus (DCP) using optical coherence tomography angiography (OCTA).MethodsParticipants with healthy retinas were recruited, and 5 × 5 mm OCTA images were acquired using the Canon HS-100 Angio eXpert module. FAZ size was measured in automatically (AS, manufacturer-based) and manually (MS, anatomical-based) segmented OCTA slabs by two experienced graders. FAZ dimensions, inter-rater agreement, and correlation to demographic and retinal parameters were evaluated.ResultsA total of 38 eyes from 20 healthy adult subjects were included in this cross-sectional study. While in AS slabs, the FAZ in the SCP was smaller than in the DCP, in MS images, it was the opposite. MS had a relevant impact on inter-rater agreement of FAZ measurements in the SCP. The FAZ area in both plexus correlated inversely with the central retinal thickness (CRT), irrespective of the segmentation applied. Furthermore, an enlargement of FAZ size in the DCP with increasing age was found. Finally, the FAZ in female participants was significantly larger than in their male counterparts, regardless of the evaluated plexus and chosen segmentation.ConclusionsCorrect anatomical slab segmentation has a significant impact on FAZ size measurements. Not adjusting the segmentation boundaries represents a significant source of error for measuring FAZ area and confounds comparisons across studies as well as OCTA devices.

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.

Background: Optical coherence tomography angiography (OCTA) is a non-invasive tool for imaging and quantifying the retinal and choroidal vasculature as well as perfusion state in healthy eyes. Choroidal perfusion is subject to diurnal variation, showing lowest perfusion in the morning and highest in the afternoon. In this index study, OCTA was used to investigate diurnal changes of the retinal perfusion in healthy adult eyes and to identify impacting factors since retinal perfusion is known to be mainly determined by autoregulatory mechanisms. Methods: A prospective study was conducted on healthy volunteers, each of whom underwent repeated measurements of mean arterial pressure (MAP), intraocular pressure (IOP), macular volume (MV), subfoveal choroidal thickness (SFCT), foveal avascular zone (FAZ) and retinal perfusion of the superficial capillary plexus (SCP), deep capillary plexus (DCP) and full retina (FR) slab at 7 a.m. and 4 p.m. Possible influence of MAP or IOP on the retinal perfusion was evaluated. Results: A total of 22 eyes of 22 participants (mean age 55.91 ± 14.84) were analysed. Significant diurnal changes from 7 a.m. to 4 p.m. were observed for MAP (p < 0.001) and SFCT (p = 0.017). The perfusion of SCP, DCP and FR as well as the size of the FAZ and the MV did not show significant fluctuation during the day. No significant correlation between MAP or IOP and retinal perfusion values were detectable. Conclusion: OCTA-based analysis of the retina in healthy adults demonstrated a steady perfusion of both plexus during the day, independently of changes in MAP. These findings support the theory of autoregulatory mechanisms of the retinal blood flow.

Zusammenfassung Hintergrund Die Corona-Pandemie hat zu einer kurzfristigen Anpassung der Lehrveranstaltungen im Studiengang Humanmedizin geführt. Präsenzlehre war in vielen Bereichen nicht mehr möglich, sodass ein digitales Lehrkonzept etabliert werden musste, um weiterhin eine adäquate medizinische Ausbildung zu gewährleisten. Methodik Basierend auf den Lehrinhalten unserer Präsenzveranstaltung, haben wir ein digitales Curriculum erarbeitet. Primäre Werkzeuge zur Umsetzung dieses Vorhabens waren Cisco WebEx und Moodle, welche bereits an der Universität zu Lübeck etablierte Softwarelösungen waren. Anschließend wurde anhand einer Umfrage unter den Studierenden dieses Konzept evaluiert. Ergebnisse Die Auswertung der Evaluation hat gezeigt, dass Inhalt und Didaktik der Lehrveranstaltung als „gut bis sehr gut“ bewertet wurden. Die Kommunikation mit den Studenten und unter den Studenten selbst wurde als „gut“ eingestuft. Es hat sich insbesondere gezeigt, dass die Aufmerksamkeit der Studenten während der Vorlesung als „gleichwertig“ zu der Aufmerksamkeit einer Präsenzvorlesung bewertet wurde. Die Vermittlung von praktischen Fähigkeiten wurde erwartungsgemäß als „schlecht“ beurteilt. Abschließend konnte sich ein Großteil der Studierenden eine Kombination aus digitaler und Präsenzlehre auch in Zukunft vorstellen. Diskussion Die kurzfristige Umstellung auf einen digitalen Lehrbetrieb hat Lehrende und Studierende vor eine Herausforderung gestellt. Durch geeignete Softwarelösungen können theoretische Inhalte adäquat vermittelt werden. Die Studenten werteten die digitale Lehrveranstaltung im Vergleich zur Präsenzlehre als gleichwertig und auch für die Zukunft als eine attraktive Option. Ein weiterhin zu lösendes Problem bleibt aber das Erlernen von praktischen Fähigkeiten.