The influence of polyacrylamide gel substrate elasticity on primary cultures of rat retinal ganglion cells.

In vitro primary cell culture models of retinal ganglion cells (RGC) are widely used to study pathomechanisms of diseases such as glaucoma. The biomechanic interaction with the culture substrate is known to influence core cellular functions. RGC cultures, however, are usually grown on rigid plastic or glass substrates. We hypothesized that soft polyacrylamide gel substrates may alter survival and neurite outgrowth of primary cultured RGC. Primary retinal cultures from postnatal (day 1-6) Wistar rats were grown on glass coverslips or polyacrylamide (PA) gel substrate with different Young's elastic moduli (0.75, 10 or 30 kPa). Substrates were coated with Poly-l-lysine and/or laminin. RGC were immunostained with anti-beta-III-tubulin. Total neurite length, growth cone morphology, RGC density, mitochondrial morphology and transport as well as pro-survival pathways (Erk1/2, Akt, CREB) were assessed. PA gel substrates of E = 10 kPa significantly increased the total neurite length by factor 1.5 compared to glass (p = 0.02). The growth cone area was significantly larger by factor 5.3 on 30 kPa gels (p = 0.01). The presence of a substrate coating was more important for neurite outgrowth and RGC survival on PA gels (poly-l-lysine > laminin) than on glass. Neither mitochondrial morphology and motility nor the activation of pro-survival pathways significantly differed between the four substrates. PA gel substrates significantly enhanced RGC neurite outgrowth. The signaling cascades mediating this effect remain to be determined.

Benefit of intravitreal injections in patients with sub-threshold baseline visual acuity: a retrospective single-centre study.

PURPOSE: To investigate the lower visual acuity threshold for recommending intravitreal injection therapy (IVI). The lower limit of 1.3 logMAR best-corrected visual acuity (BCVA) was adopted in 2006 and has been maintained since then. METHODS: In this retrospective study, data from patients with a logMAR BCVA ≤ 1.3 and 24 months follow-up were analysed. We included patients with neovascular age-related macular degeneration (nAMD), diabetic macular oedema (DME), or retinal vein occlusion (RVO). RESULTS: The data from 164 patients (nAMD: 107; DME: 15; RVO: 42) were analysed. We observed a significant improvement at all time intervals (0 to 6, 6 to 12, 12 to 18, and 18 to 24 months after initiating IVI) compared to baseline. Across all indications, median BCVA improved from 1.4 to 1.0 within the first 6 months and remained stable within 24 months. Patients received a median of 5 and 10 injections within 6 and 24 months, respectively. Median foveal retinal thickness was 594.5 µm at baseline and dropped to 244.5 µm, 235.5 µm, 183 µm, and 180 µm during the four consecutive time intervals. CONCLUSION: Patients with nAMD, DME, and RVO with poor baseline BCVA may also benefit from intravitreal therapy with VEGF-inhibitors. In the present study, we observed functional and morphological improvement over 2 years irrespective of the underlying macular disease. Those patients should not be excluded from therapy.

Reorganization of the perifoveal microvasculature after macular hole closure assessed via optical coherence tomography angiography.

PURPOSE: To quantify short-term microvascular changes after pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling in patients with idiopathic macular hole (IMH) using optical coherence tomography angiography (OCTA). DESIGN: Cohort Study. PARTICIPANTS: This study included patients with IMH. Affected eyes were compared with fellow eyes. METHODS: 6 × 6 mm OCTA (Zeiss Angioplex, Zeiss Meditec, Dublin, CA, USA) images of the study eye and fellow eye were acquired one day before surgery, 4 weeks and 12 weeks after surgery. Microvascular alterations in the superficial and deep capillary plexus were assessed by measuring vessel density and the shortest distance to the surrounding vessels of all intercapillary pixels. Only vessels enclosed by an ETDRS Grid centered on the fovea were analyzed. MAIN OUTCOME MEASURES: Change of vessel density and vessel distance to baseline. RESULTS: OCTA images of the 15 study and 15 fellow eyes of 15 included patients (mean ± SD of age: 67.89 ± 5.2 years) were analyzed and revealed a significant increase in vessel density and decrease in vessel distance of the deep capillary plexus in study eyes 4 weeks after surgery compared to baseline. Our superficial capillary plexus findings were the inverse, namely a significant decrease in vessel density and increase in vessel distance. Postoperative microvascular changes proved to be closely associated with the extent of retinal thickness reduction in the perifoveal deep capillary plexus. CONCLUSIONS: IMH closure after PPV and ILM peeling caused a significantly improved microvasculature in the deep capillary plexus, which may represent reorganized perifoveal microvasculature due to the regression of cystoid spaces.

Risk of perioperative bleeding complications in rhegmatogenous retinal detachment surgery: a retrospective single-center study.

PURPOSE: The goal of this study was to analyze the incidence of perioperative bleeding complications in rhegmatogenous retinal detachment. The handling of perioperative anticoagulation during vitreoretinal surgery remains controversial, since the risk of bleeding complications by its continuation has to be balanced against the risk of progression of retinal detachment and the risk of thromboembolic events when anticoagulation is interrupted. Nevertheless, only few studies have investigated the risk of perioperative bleeding complications in an emergency such as retinal detachment surgery. METHODS: We therefore examined the rate of all perioperative hemorrhages and separately the rate of only severe bleedings during vitrectomy, scleral buckling with or without drainage of subretinal fluid (SRD), or combined procedures due to retinal detachment in patients undergoing different types of perioperative anticoagulation including acetylsalicylic acetate (ASA), clopidogrel, heparin, low molecular weight heparin, and phenprocoumon. RESULTS: This retrospective single-center study included 893 patients with primary rhegmatogenous retinal detachment, n = 192 on anticoagulation and n = 701 serving as control without anticoagulation. Our analysis revealed no significantly increased rate of perioperative hemorrhages under anticoagulation with ASA 100 mg (all, 11.4%; severe, 5.0%) or phenprocoumon (all, 11.6%; severe, 2.3%) compared with controls (all, 13.0%; severe, 5.4%). However, frequencies of bleeding complications varied markedly regarding the type of surgical procedure: Scleral buckling plus SRD showed the highest rates of hemorrhages (all, 18.9%; severe, 9.1%) with significant difference (P < 0.001) compared with scleral buckling without SRD (all, 3.8%; severe, 0.6%) and vitrectomy (all, 9.2%; severe, 1.5%), respectively. Furthermore, subretinal bleeding was the most common type of perioperative hemorrhage. CONCLUSIONS: The data suggest not to stop ASA therapy prior to vitreoretinal surgery. Furthermore, we found no evidence of an increased risk for perioperative bleedings in patients under anticoagulation with vitamin-k antagonists with an INR within the sub-therapeutic range. SRD during scleral buckling procedure should be avoided as possible and regardless of any type of anticoagulation.

Chronic Lung Allograft Dysfunction: Oxygen-enhanced T1-Mapping MR Imaging of the Lung.

PURPOSE: To evaluate oxygen-enhanced T1-mapping magnetic resonance (MR) imaging of the lungs for detection of chronic lung allograft dysfunction (CLAD) in patients who have undergone double lung transplantation. MATERIALS AND METHODS: The local ethics committee approved this study. Seventy-six recipients of double lung allografts who underwent MR imaging of the lungs during an outpatient visit between 2011 and 2013 were included in this study after they provided written informed consent. Patients were classified as having CLAD on the basis of spirometric results and were divided into three groups: no CLAD (bronchiolitis obliterans syndrome level 0 [BOS 0]), early CLAD (BOS 0p), and late-stage CLAD (BOS 1-3). Coronal T1 maps of the lungs were acquired with the patient breathing room air and 100% oxygen by using an inversion-recovery snapshot fast low-angle shot sequence at 1.5 T. The median and interquartile range of T1 values at room air and at 100% oxygen and the oxygen transfer function were calculated. Statistical analysis was performed with analysis of variance and the Tukey honestly significant difference test or the Kruskal-Wallis test and the Mann-Whitney U test (α = 0.05). Bonferroni correction was applied for multiple comparisons. RESULTS: The oxygen transfer function was significantly lower in patients in the BOS 0p (P = .025) and BOS 1-3 groups (P = .003) than it was in the patients with BOS 0. Absolute T1 values (room air, P = .66; 100% oxygen, P = .67) did not differ significantly among the groups. The heterogeneity of T1 values, measured by using the interquartile range, showed a strong trend toward higher values in patients with BOS (room air, P = .06; 100% oxygen, P = .08). CONCLUSION: Oxygen transfer function may serve as an early marker for detection of CLAD.

Clinical use of oxygen-enhanced T1 mapping MRI of the lung: reproducibility and impact of closed versus loose fit oxygen delivery system.

PURPOSE: To evaluate the reproducibility of oxygen-enhanced magnetic resonance imaging (MRI), and the influence of different gas delivery methods, in a clinical environment. MATERIALS AND METHODS: Twelve healthy volunteers were examined on two visits with an inversion recovery snapshot fast low angle shot sequence on a 1.5 T system. Coronal slices were obtained breathing room air as well as 100% oxygen with a flow rate of 15 L/min. For oxygen delivery a standard nontight face mask and a full closed air-cushion face mask were used. T1 relaxation times and the oxygen transfer function (OTF) were calculated. RESULTS: The mean T1 values did not change significantly between the two visits (P > 0.05). The T1 values breathing 100% oxygen obtained using the full closed mask were significantly lower (1093 ± 38 msec; P < 0.05) compared to the standard mask (1157 ± 52 msec). Accordingly, the OTF was significantly higher for the full closed mask (P < 0.05). The OTF changed significantly on the second visit using the standard mask (P < 0.05). The full closed mask showed lower interindividual variation for both the T1 values (3.5% vs. 4.5%) as well as the OTF (12.4% vs. 22.0%) and no difference of the OTF on the second visit (P > 0.05). CONCLUSION: Oxygen-enhanced T1 mapping MRI produces reproducible data when using a full closed face mask.

Influence of the Size of the Foveal Avascular Zone on Functional and Morphological Parameters in Patients with Early-Stage Diabetic Retinopathy.

Purpose: To correlate functional and morphological parameters with foveal avascular zone's (FAZ) size in diabetic patients with mild to moderate stage nonproliferative diabetic retinopathy. Methods: Monocentric and prospective study of a consecutive case series of diabetic patients. Medical history, best corrected visual acuity (BCVA), best corrected high/low contrast visual acuity (BChcVA/BClcVA), mean sensitivity (MS) and mean defect (MD) in central visual field testing, and FAZ size in fluorescein-angiography (FAG) were recorded. Macular thickness (central point thickness CPT, central subfield thickness CST) and volume measurements (central subfield volume CSV, total macular volume) were taken from SD-OCT (6x6mm ETDRS-grid). Groups were categorised as presenting FAZ sizes smaller (G1) or larger (G2) than 0.35mm2. Smallest (Q1) and largest quartiles (Q3) were also compared. Results: Thirty-six of 40 patients were included. MS differed significantly between G1 (n = 6) and G2 (n = 30), and BChcVA/BClcVA as well as TMV correlated significantly with FAZ size in correlation analysis. Mean HbA1c tended to be lower in G1 than G2. Patients in G1 were slightly older than in G2. Treatment period with insulin was shorter in G1/Q1 than in G2/Q3. CPT and TMV were lower in G1/Q1 than in G2/Q3. Our analysis of the FAZ in terms of patient age, HbA1c, disease duration and insulin therapy duration revealed no significance. That lack of significance also applies to BCVA, MS, MD, CPT, CST and CSV. Conclusion: As significantly associated, contrast sensitivity, central visual field parameters and potentially retinal thickness or volume seem to be suitable to detect early macular ischaemia. However, we failed to establish any correlation between FAZ and BCVA.

Risk Factors for Severe Bleeding Complications in Glaucoma Surgery and the Role of Antiplatelet or Anticoagulant Agents.

Purpose: To evaluate the influences and risk factors for severe bleeding complications during glaucoma surgery, and to investigate the role of antiplatelet (AP) and anticoagulant (AC) agents. Methods: This prospective study enrolled patients undergoing trabeculectomy, trabeculotomy (with Trabectome® or Kahook Dual Blade®), viscocanaloplasty and Ahmed or Baerveldt implants. Bleeding severity was graded on an ordinal scale ranging from 0 to 5. Immediately after surgery and one day later, the incidence and severity of bleeding events was documented on a standardized form. A grade ≥3 was defined as severe bleeding. The influence of known systemic disorders, the type of anesthesia, surgical procedure, intraoperative blood pressure, and the use of or change in AP or AC agents on intraoperative bleeding were analyzed. Results: Data from 89 eyes undergoing glaucoma procedures were included (age 71.3y ± 10.5). We observed severe intraoperative bleeding in 8 eyes (9%) and found that concomitant diseases such as the history of a deep vein thrombosis or peripheral arterial occlusive disease, and the type of surgical procedure (trabeculectomy and viscocanaloplasty) were significantly associated with severe bleeding events. By contrast, the use of AP/ AC agents had no significant influence on severe intraoperative bleeding events. Conclusion: According to the results of our study cohort, glaucoma procedures entailing scleral manipulations (trabeculectomy and viscocanaloplasty) and concomitant diseases such as the history of a deep vein thrombosis or peripheral arterial occlusive disease influence the risk of severe intraoperative bleeding events, we detected no increased risk related to concomitant antiplatelet and/ or anticoagulant medication use.

Reliability of Subjective Assessment of Spectral-Domain OCT Pathologic Features by Multiple Raters in Retinal Vein Occlusion.

Purpose: To examine the interrater and intrarater reliability of qualitatively and quantitatively assessed disorganization of retinal inner layers (DRIL) and disorganization of retinal outer layers (DROL) by multiple raters. Subjectively assessing these surrogate biomarkers can be challenging in daily routine, despite the high resolution of spectral-domain (SD) OCT scans. Design: Retrospective trial. Participants: Three hundred six pooled SD OCT scans of 34 patients treated for macular edema caused by retinal vein occlusion (RVO) between January 2016 and December 2017. Methods: SD OCT scans were assessed by 6 raters regarding presence of cystoid macular edema, subretinal fluid (SRF), vitreoretinal traction, and epiretinal membrane and extent of DRIL and DROL. Main Outcome Measures: Interrater and intrarater reliability were calculated applying κ statistics for qualitative assessment regarding each pathologic feature's presence in all evaluated OCT scans, and for quantified horizontal DRIL and DROL extent within each OCT cross-section. Results: Cystoid macular edema and SRF assessments revealed excellent inter- and intrarater reliability with almost perfect strength of agreement, whereas subjective DRIL and DROL evaluations yielded low κ statistics with slight to moderate strength of agreement. Furthermore, the presence of SRF remarkably compromised the reliability of DROL detection. Conclusions: Our data highlight the limited subjective assessibility of DRIL and DROL, underscoring the need for automated image analysis to improve the reliability of OCT biomarkers for clinical studies and daily practice.

Risk Factors for Severe Bleeding Complications in Vitreoretinal Surgery and the Role of Antiplatelet or Anticoagulant Agents.

PURPOSE: To evaluate the influences and risk factors for severe bleeding complications during vitreoretinal surgery and to investigate the role of antiplatelet and anticoagulant agents. DESIGN: Prospective trial. PARTICIPANTS: Patients undergoing vitreoretinal surgery. METHODS: The procedures included were pars plana vitrectomy and scleral buckling. We developed a uniform classification to grade the bleeding severity. Bleeding was graded on an ordinal scale ranging from 0 to 5. Immediately after surgery and 1 day later, the incidence and the severity of bleeding events was documented on a standardized form. A grade of 3 or more was defined as severe bleeding. Furthermore, the influence of known systemic disorders before surgery, the type of anesthesia, type of surgical procedure, intraoperative blood pressure, and the use or change of antiplatelet or anticoagulant agents on intraoperative bleeding was analyzed. MAIN OUTCOME MEASURES: Incidence and risk factors for severe intraoperative bleeding events. RESULTS: Data from 374 eyes undergoing vitreoretinal procedures were included in our study (mean age, 67.6 ± 12.9 years). A severe intraoperative bleeding event was observed in 15 eyes (4%). We found that concomitant diseases such as diabetes mellitus and carotid artery stenosis, the presence of diabetic retinopathy, younger age, and scleral buckling combined with a transscleral puncture were associated significantly with severe bleeding events. By contrast, use of antiplatelet or anticoagulant agents, or both, had no significant influence on severe intraoperative bleeding events. CONCLUSIONS: Although external manipulations during buckling surgery (e.g., drainage of subretinal fluid) and concomitant diseases such as diabetes mellitus and carotid artery stenosis influences the risk of severe intraoperative bleeding events, we did not detect an increased risk related to coexisting antiplatelet or anticoagulant medication use, or both.

Diagnosing SARS-CoV-2 with Antigen Testing, Transcription-Mediated Amplification and Real-Time PCR.

This study was performed as a head-to-head comparison of the performance characteristics of (1) two SARS-CoV-2-specific rapid antigen assays with real-time PCR as gold standard as well as (2) a fully automated high-throughput transcription-mediated amplification (TMA) assay and real-time PCR in a latent class analysis-based test comparison without a gold standard with several hundred samples in a low prevalence "real world" setting. Recorded sensitivity and specificity of the NADAL and the LumiraDx antigen assays and the Hologic Aptima SARS-CoV-2 TMA assay were 0.1429 (0.0194, 0.5835), 0.7644 (0.7016, 0.8174), and 0.7157 (0, 1) as well as 0.4545 (0.2022, 0.7326), 0.9954 (0.9817, 0.9988), and 0.9997 (not estimable), respectively. Agreement kappa between the positive results of the two antigen-based assays was 0.060 (0.002, 0.167) and 0.659 (0.492, 0.825) for TMA and real-time PCR. Samples with low viral load as indicated by cycle threshold (Ct) values > 30 were generally missed by both antigen assays, while 1:10 pooling suggested higher sensitivity of TMA compared to real-time PCR. In conclusion, both sensitivity and specificity speak in favor of the use of the LumiraDx rather than the NADAL antigen assay, while TMA results are comparably as accurate as PCR, when applied in a low prevalence setting.

There is no intraocular affection on a SARS-CoV-2 - Infected ocular surface.

PURPOSE: The presence of SARS-CoV-2 RNA in anterior chamber fluid and/or the vitreous in patients with SARS-CoV-2 RNA on the ocular surface is unclear. Knowledge about the infectious state of intraocular structures could influence the daily work of ophthalmic surgeons. OBSERVATIONS: We analyzed ocular samples from a patient who had succumbed to COVID-19 pneumonia for the prevalence of SARS-CoV-2 RNA. We detected viral RNA in the ocular-surface samples on one swab and in one excidate from the conjunctiva. Samples from the anterior chamber and vitreous revealed no SARS-CoV-2 RNA. CONCLUSIONS: SARS-CoV-2 can effectively be inactivated with standard disinfection agents. The now proven absence of SARS-CoV-2 in intraocular fluids could influence how ophthalmic surgeons work. Without having to account for the risk of a contagion via the anterior chamber and/or vitreous body, the surgical staff would require no additional, more elaborate protection.

Influence of pars plana vitrectomy for macular surgery on the medium term intraocular pressure.

PURPOSE: To evaluate the long-term effect of 20 and 23 gauge pars plana vitrectomy (PPV) on intraocular pressure (IOP). METHODS: Study type: Monocentric retrospective cohort study. 249 eyes of 249 patients undergoing PPV due to epiretinal membrane (EM), idiopathic macular hole (IMH) or vitreoretinal traction (VT) were included. The fellow eye served as control. Exclusion criteria were factors known to influence the IOP, such as cataract surgery during follow-up, extended use of steroids, cryotherapy and silicone oil endotamponade. The relative change of IOP (operated vs. fellow eye) at 6-12 months after surgery was defined as primary endpoint. Secondary endpoints were the relative change of IOP at 3-6 and 12-24 months. Possible influencing cofactors were analysed using ANCOVA. RESULTS: The primary endpoint did not show a significant IOP reduction of the operated eye relative to the fellow eye (P = 0.089, n = 84). However, the IOP of the operated eye alone was significantly reduced at 6-12 and 12-24 months after surgery (-0.75 ± 2.80 and -1.22 ± 3.29 mmHg, P = 0.008 and 0.007, respectively). The IOP of the fellow eye was also significantly reduced at the 12-24 months period (-0.75 ± 2.73 mmHg, P = 0.008). In the subgroup analysis, sclerotomy size was a significant influencing cofactor, leading to lower IOP after 20G compared to 23G vitrectomy (P = 0.04). CONCLUSION: Pars plana vitrectomy did not induce a significant long-term IOP reduction relative to the contralateral eye. However, we observed a IOP lowering potential in 20G vitrectomy.

Distance-Thresholded Intercapillary Area Analysis Versus Vessel-Based Approaches to Quantify Retinal Ischemia in OCTA.

PURPOSE: To develop and compare different analytic approaches for quantifying ischemia in OCT-angiography (OCTA), including vessel-based approaches and intercapillary area analysis. METHODS: En face OCTA (6 × 6) images of the superficial plexus of 20 healthy eyes and 20 eyes with different ischemic retinal diseases were analyzed retrospectively. Included retinal diseases were diabetic retinopathy (n = 9), central (n = 5) and branch retinal vein occlusion (n = 4), hypertensive retinopathy (n = 1), and occlusive retinal vasculitis in sarcoidosis (n = 1). Vessel-based approaches consisted of the mean gray scale, perfusion density, and vessel density. Intercapillary areas (ICAs) were analyzed measuring the distance of each intercapillary pixel from the surrounding vessels. In particular, we applied a vector method to measure the shortest, the mean, and the longest distance in eight predefined directions. Size of ICAs was determined applying different global or local distance thresholds. RESULTS: All approaches revealed significant differences between ischemic and healthy retinae (P < 0.001, with Bonferroni-Holm correction P = 0.001-0.025; Wilcoxon-Mann-Whitney test). Discrimination between the healthy and ischemic retinae based on ROC curves was best in the ICA analysis using a locally set threshold of the shortest distance. CONCLUSIONS: In the present study, ICA analysis was superior to vessel-based approaches in the quantification of retinal ischemia when defining a local or global distance threshold. TRANSLATIONAL RELEVANCE: In order to establish OCTA imaging in everyday clinical and scientific practice, standardized, device-independent image analysis methods are necessary.