["Flipped classroom"-A future concept for student teaching in ophthalmology?] / "Flipped classroom" ­ Ein Zukunftskonzept für die studentische Lehre in der Augenheilkunde?

BACKGROUND: "Flipped classroom" is a didactic teaching concept in which learning contents are prepared by self-study with arranged tools before the classroom session. The concept offers the advantage of a uniform knowledge base for the students at the beginning of the course and also the advantage of a greater theoretical knowledge, which creates more opportunities for practical exercises, application and consolidation in the subsequent joint teaching units. This study describes the establishment and application of such a model in student teaching in ophthalmology and analyzes the student's evaluation. METHODOLOGY: For the winter term 2018/2019, a new teaching module was designed and established in a cooperation between the department of ophthalmology and the Institute for Education and Study Affairs (IfAS) at the medical faculty of the University of Münster. A uniform training of the lecturers as well as a preparation of the students for the restructuring took place. After the course the evaluation of the students was recorded and evaluated using a standardized online evaluation. RESULTS: Between the winter semester 2018/2019 and the winter semester 2019/2020, an average of 112.3 ± 4.0 students were taught with the "flipped classroom" model. Of these 93.7% were able to give an assessment. In the previous semesters with the old teaching concept (summer semester 2015 to summer semester 2018), the average number of students was 115.4 ± 15.1 with an assessment rate of 93.3%. The new teaching concept achieved on average a better assessment than the old module. CONCLUSION: With a "flipped classroom" space and flexibility can be generated for a more individual course preparation and at the same time a higher practical part. Further studies are needed to analyze whether this also enables a sustainable transfer of knowledge.

Automated OCT angiography image quality assessment using a deep learning algorithm.

PURPOSE: To expedite and to standardize the process of image quality assessment in optical coherence tomography angiography (OCTA) using a specialized deep learning algorithm (DLA). METHODS: Two hundred randomly chosen en-face macular OCTA images of the central 3 × 3 mm2 superficial vascular plexus were evaluated retrospectively by an OCTA experienced reader. Images were defined either as sufficient (group 1, n = 100) or insufficient image quality (group 2, n = 100) based on Motion Artifact Score (MAS) and Segmentation Accuracy Score (SAS). Subsequently, a pre-trained multi-layer deep convolutional neural network (DCNN) was trained and validated with 160 of these en-face OCTA scans (group 1: 80; group 2: 80). Training accuracy, validation accuracy, and cross-entropy were computed. The DLA was tested in detecting 40 untrained OCTA images (group 1: 20; group 2: 20). An insufficient image quality probability score (IPS) and a sufficient image quality probability score (SPS) were calculated. RESULTS: Training accuracy was 97%, validation accuracy 100%, and cross entropy 0.12. A total of 90% (18/20) of the OCTA images with insufficient image quality and 90% (18/20) with sufficient image quality were correctly classified by the DLA. Mean IPS was 0.88 ± 0.21, and mean SPS was 0.84 ± 0.19. Discrimination between both groups was highly significant (p < 0.001). Sensitivity of the DLA was 90.0%, specificity 90.0%, and accuracy 90.0%. Coefficients of variation were 0.96 ± 1.9% (insufficient quality) and 1.14 ± 1.6% (sufficient quality). CONCLUSIONS: Deep learning (DL) appears to be a potential approach to automatically distinguish between sufficient and insufficient OCTA image quality. DL may contribute to establish image quality standards in this recent imaging modality.

Prevalences of segmentation errors and motion artifacts in OCT-angiography differ among retinal diseases.

PURPOSE: To assess the prevalences of segmentation errors and motion artifacts in optical coherence tomography angiography (OCT-A) in different retinal diseases METHODS: In a retrospective analysis, multimodal retinal imaging including OCT-A was performed in one eye of 57 healthy controls (50.96 ± 22.4 years) and 149 patients (66.42 ± 14.1 years) affected by different chorioretinal diseases: early/intermediate age-related macular degeneration (AMD; n = 26), neovascular AMD (nAMD; n = 22), geographic atrophy due to AMD (GA; n = 6), glaucoma (n = 28), central serous chorioretinopathy (CSC; n = 14), epiretinal membrane (EM; n = 26), retinal vein occlusion (RVO; n = 11), and retinitis pigmentosa (RP; n = 16). Central 3 × 3 mm2 OCT-A imaging was performed with active eye-tracking (AngioVue, Optovue). Best-corrected visual acuity (BCVA) and signal strength index (SSI) were recorded. Images were independently evaluated by two graders using the OCT-A motion artifact score (MAS; scores I-IV) as well as a newly introduced segmentation accuracy score (SAS; score I-IIB). RESULTS: Mean SSI was 63.67 ± 9.2 showing a negative correlation with increasing age (rSp = - 0.42, p < 0.001, n = 206). In the healthy cohort, mean MAS was 1.45 ± 0.8 and segmentation was accurate (SAS I) in all eyes. In eyes with retinal pathologies, mean MAS was 2.1 ± 0.9 (p < 0.001). Lowest MAS was observed in GA (2.67 ± 0.5) and RVO (2.45 ± 1.1). Compared to an accurate segmentation in 100% in healthy subjects, 34.2% (n = 51) of all patients showed highest segmentation quality (p < 0.001). 63.8% showed segmentation errors in more than 5% of all single b-scans in one (SAS IIA, n = 58) or at least two (SAS IIB, n = 40) segmentation boundaries. Highest percentages of inaccurate segmentation (SAS IIA or IIB) were observed in the nAMD group (90.1%). The inner plexiform layer was the segmentation boundary most prone to inaccurate segmentation in all pathologies compared to the inner limiting membrane (ILM) and retinal pigment epithelium (RPE) segmentation layer. Incorrect ILM segmentation was only seen in patients with EM. CONCLUSIONS: Prior to both qualitative and quantitative analysis, OCT-A images must be carefully reviewed as motion artifacts and segmentation errors in current OCT-A technology are frequent particularly in pathologically altered maculae.

[Flow density measurements using optical coherence tomography angiography : Impact of age and gender]. / Messung der Flussdichte mittels OCT-Angiographie : Einfluss von Alter und Geschlecht.

BACKGROUND: This article presents the normative data for flow density measured using optical coherence tomography (OCT) angiography and the impact of age and gender is evaluated. METHODS: In this study 58 eyes from 58 healthy volunteers with no history of any ocular disease or ocular surgery were included. The OCT angiography imaging was performed using the RTVue XR Avanti with the AngioVue (Optovue, Fremont, CA). The macula was imaged using a 3 × 3 mm scan, and the flow density data in the superficial retinal OCT angiogram and deep retinal OCT angiogram were extracted and analyzed. The groups were compared using the Mann-Whitney U­test and the degree of correlation between two variables was expressed as the Spearman's correlation coefficient (rSp.) RESULTS: The mean subject age was 38.3 ± 14.6 years. The flow density (whole en face) in the deep retinal OCT angiogram was significantly higher compared to the flow density in the superficial retinal OCT angiogram (p < 0.001). There was no significant difference in the mean flow density in superficial and deep OCT angiograms of the macula between males (n = 27) and females (n = 31). There was a significant correlation between the flow density in the deep retinal OCT angiogram and age (rSp. = -0.41, p = 0.001). CONCLUSION: Whereas gender has no impact on the flow density measured using OCT angiography, there was a significant correlation between the flow density in the deep retinal OCT angiogram and age.

Signal reduction in choriocapillaris and segmentation errors in spectral domain OCT angiography caused by soft drusen.

PURPOSE: To analyze signal reduction in choriocapillaris (CC) and segmentation errors in spectral domain optical coherence tomography angiography (OCT-A) caused by soft drusen due to age-related macular degeneration (AMD). METHODS: Twenty-four eyes of 24 patients underwent multimodal retinal imaging including central 3 × 3mm2 OCT-A (AngioVue, Optovue). Three drusen per study eye were randomly chosen and evaluated regarding drusen height, diameter, and accuracy of OCT-A layer segmentation in lesion proximity. Structural en-face OCT CC images were graded qualitatively and quantitatively regarding signal loss underneath the individual drusen area. Those drusen that showed no distinct signal loss in structural en-face OCT CC images were further evaluated in OCT-A. CC decorrelation signal index was measured within a 30-µm OCT-A CC slab in the exact area of drusen affection. Data were compared to healthy age-matched control subjects. Accuracy of layer segmentation, OCT CC data, and OCT-A CC data were correlated to morphological drusen parameters. RESULTS: Mean drusen height and diameter were 91.57 ± 19.5µm and 315.17 ± 116.7µm. OCT-A layer segmentation of the inner plexiform layer (IPL) was disturbed by more than 50 µm in proximity to 26 drusen (36.1%). In these patients, drusen height was significantly higher compared to those with accurate IPL segmentation (p = 0.0126). Sixty-six out of 72 drusen (91.7%) caused a distinct signal loss in the structural en-face OCT CC image. Drusen height and drusen diameter were significantly higher in this group compared to the six drusen with a sufficient signal (p = 0.0276, p = 0.0025). CC decorrelation signal index measured in the area of these six drusen without OCT signal loss (8.3%) was reduced compared to age-matched healthy controls (73.6 vs. 100.1; p = 0.001). CONCLUSIONS: Signal attenuation in CC slabs and segmentation errors of the IPL depend on drusen morphology. Both are frequent artifacts in OCT-A imaging in patients with soft drusen and must be considered during image analysis.

Impact of eye-tracking technology on OCT-angiography imaging quality in age-related macular degeneration.

OBJECTIVE: To evaluate the impact of eye-tracking (ET) technology on optical coherence tomography angiography (OCT-A) image quality and manifestation of motion artifacts in patients with age-related macular degeneration (AMD). METHODS: In a prospective trial, multimodal retinal imaging including OCT-A was performed in 30 patients (78.97 ± 9.7 years) affected by different stages of AMD. Central 3 × 3 mm2 OCT-A imaging was performed four times consecutively in each patient, twice with active, and twice with inactive ET. Parameters for image evaluation were signal strength index (SSI), variability of foveal vessel density (VD), acquisition time, presence of motion artifacts caused by eye movement (blink lines, displacement) and by software correction of eye movement (quilting, stretch artifacts, vessel doubling). Images were evaluated by two independent readers with subsequent senior reader arbitration for presence of artifacts, and an OCT-A motion artifact score (MAS) was calculated. RESULTS: Eight patients had early and eight patients had intermediate stages of AMD. Four patients had an atrophic late stage and ten patients an exudative stage of the disease. SSI was 53.55 with inactive and 57.18 with active ET (p = 0.0005). Coefficients of variability of VD between the first and second measurement were 8.9% with inactive and 5.7% with active ET. Mean image acquisition time was 15.97 s (active ET: 22.88 s, p < 0.001). Presence of motion artifacts was significantly higher with inactive ET (mean MAS 3.27 vs. 1.93; p < 0.0001). MAS correlated with AMD disease stage [p = 0.0031 (inactive ET) and p < 0.0001 (active ET)] and with SSI (p = 0.0072 and p = 0.0006). CONCLUSIONS: In patients with AMD, active ET technology offers an improved image quality in OCT-A imaging regarding presence of motion artifacts at the expense of higher acquisition time.

Comparison of Technical and Clinical Outcome of Transjugular Portosystemic Shunt Placement Between a Bare Metal Stent and a PTFE-Stentgraft Device.

PURPOSE: To analyse technical and clinical success of transjugular intrahepatic portosystemic shunt (TIPS) in patients with portal hypertension and compare a stent and a stentgraft with regard to clinical and technical outcome and associated costs. MATERIALS AND METHODS: 170 patients (56 ± 12 years, 32.9% females) treated with TIPS due to portal hypertension were reviewed. 80 patients received a stent (group 1) and 83 a stentgraft (group 2), and seven interventions were unsuccessful. Technical data, periprocedural imaging, follow-up ultrasound and clinical data were analysed with focus on technical success, patency, clinical outcome and group differences. Cost analysis was performed. RESULTS: Portal hypertension was mainly caused by ethyltoxic liver cirrhosis with ascites as dominant symptom (80%). Technical success was 93.5% with mean portosystemic gradient decrease from 16.1 ± 4.8 to 5.1 ± 2.1 mmHg. No significant differences in technical success and portosystemic gradient decrease between the groups were observed. Kaplan-Meier analysis yielded significant differences in primary patency after 14 days, 6 months and 2 years in favour of the stentgraft. Both groups showed good clinical results without significant difference in 1-year survival and hepatic encephalopathy rate. Costs to establish TIPS and to manage 2-year follow-up with constant patency and clinical success were 8876 € (group 1) and 9394 € (group 2). CONCLUSION: TIPS is a safe and effective procedure to manage portal hypertension. Stent and stentgraft enabled good technical and clinical results with a low complication rate. Primary patency rates are clearly in favour of the stentgraft, whereas the stent was more cost effective with similar clinical results in both groups.