Current and future approaches in the prevention and treatment of diabetic retinopathy

Diabetic retinopathy (DR) is a major cause of blindness worldwide and is the number one cause of blindness in working-age individuals in developed countries. We review the current literature and discuss the pathogenesis, modifying risk factors, genetics, and treatment of DR. Special focus is placed on the rationale and effectiveness of therapeutic modalities, both current and future

Distinctive Mechanisms and Patterns of Exudative Versus Tractional Intraretinal Cystoid Spaces as Seen With Multimodal Imaging.

PurposeTo determine clear-cut distinctions between tractional and exudative intraretinal cystoid spaces subtypes.DesignRetrospective, multicenter, observational case series.MethodsA cohort of patients diagnosed with intraretinal cystoid spaces and imaged with optical coherence tomography (OCT), fluorescein angiography (FA), blue fundus autofluorescence (BFAF), en face OCT, and OCT angiography (OCT-A) was included in the study. All images were qualitatively and quantitatively evaluated.ResultsIn this study were included 72 eyes of 69 patients. Exudative intraretinal cystoid spaces (36/72 eyes, 50%) displayed a "petaloid" morphology as seen with en face OCT, FA, and BFAF. Tractional intraretinal cystoid spaces (24/72 eyes, 33.3%), displayed a radial "spoke-wheel" en face OCT pattern. There was no leakage with FA and BFAF did not reveal specific patterns. Eyes with full-thickness macular hole (FTMH, 12/72 eyes, 16.7%) displayed a "sunflower" en face OCT appearance. FTMH showed OCT, OCT-A, and BFAF features of both exudative and tractional cystoid spaces, but without any FA leakage. Inner nuclear layer (INL) thickness was significantly lower in tractional cystoid spaces (P < .001). There were a greater number of INL cystoid spaces in both the exudative and FTMH subgroups (P = .001). The surface area of INL cystoid spaces was significantly lower in the tractional subgroup (P < .001). There was a significant reduction of the microvascular density in eyes with exudative vs tractional (P = .002) and FTMH (P < .001) subgroups.ConclusionsExudative and tractional intraretinal cystoid spaces displayed characteristic multimodal imaging features and they may represent 2 different pathologic conditions with equally different clinical implications

Alterations in the Choriocapillaris in Intermediate Age-Related Macular Degeneration.

Purpose The purpose of this study was to compare the choriocapillaris plexus in eyes with intermediate AMD (iAMD), with or without neovascular AMD in the fellow eye, using optical coherence tomography angiography (OCTA). Methods We collected data from 42 eyes with iAMD from 42 patients who had obtained OCTA. This cohort was divided into two subgroups according to the status of the fellow eye, yielding a group of 20 cases with bilateral intermediate AMD (bilateral iAMD group) and 22 cases with neovascular AMD in the fellow eye (unilateral iAMD group). An additional control group of 20 eyes from 20 healthy subjects was included for comparison. Main outcome measures were: (1) the percent of nondetectable perfused choriocapillaris area and (2) the average choriocapillaris signal void size. Results No differences in the percent of nondetectable perfused choriocapillaris area were found among the three groups (2.3 ± 1.4% in the unilateral iAMD group, 1.5 ± 0.9% in the bilateral iAMD group, and 1.7 ± 1.4% in the control group, respectively). The average choriocapillaris signal void size, however, was significantly increased in unilateral iAMD eyes (293.7 ± 71.2 μm2) compared to both bilateral iAMD (241.5 ± 51.6 μm2, P = 0.031) and control (212.7 ± 48.6 μm2, P = 0.001) eyes. Conclusions Intermediate AMD eyes of patients with neovascular AMD in the fellow eye have an increased average choriocapillaris signal void size compared to eyes without neovascular AMD in the fellow eye. If replicated in future studies, choriocapillaris signal void size may prove to be a useful parameter for evaluating eyes with AMD

Evaluation of the Choroid in Eyes With Retinitis Pigmentosa and Cystoid Macular Edema

Purpose: To study the anatomical choroidal features associated with the presence of cystoid macular edema (CME) in eyes with retinitis pigmentosa (RP). Methods: A total of 159 eyes (from 159 patients) with a diagnosis of RP were enrolled in this retrospective cross-sectional case-control study and divided into two groups based on the presence (67 eyes) or absence (92 eyes) of CME. Retinal and choroidal features were evaluated on spectral domain optical coherence tomography including central macular thickness (CMT) and subfoveal choroidal thickness (CT). Total choroidal area (TCA), choroidal luminal area (LA), and choroidal stromal area (SA) were measured and the choroidal vascularity index (CVI) was calculated in all study eyes. Results: Average age was 49.2 ± 14.9 and 47.1 ± 15.5 years (P = 0.40) and logMAR Snellen visual acuity (VA) was 0.4 ± 0.6 (median 0.3, 20/40) and 0.2 ± 0.4 (median 0.1, 20/25) in the RP groups with and without CME, respectively (P = 0.05). Mean CMT was 334.1 ± 93.5 and 252.6 ± 47.6 μm in the RP groups with and without CME, respectively (P < 0.001). The subfoveal CT was significantly increased in the RP group with versus without CME (294.2 ± 110.9 μm vs. 198.1 ± 75.5 μm, respectively, P < 0.001). In patients with CME, the CVI was lower (P < 0.001) and the TCA, LA, and SA were all significantly higher (P < 0.001). Conclusions: In patients with CME associated with RP, the choroid exhibited significantly greater subfoveal thickening and decreased CVI. The choroid may be an important factor to consider in the etiology of CME in patients with RP

Volume Rendering of Dense B-Scan Optical Coherence Tomography Angiography to Evaluate the Connectivity of Macular Blood Flow

Purpose: To characterize macular blood flow connectivity using volume rendering of dense B-scan (DB) optical coherence tomography angiography (OCTA) data. Methods: This was a prospective, cross-sectional, observational study. DB OCTA perifoveal scans were performed on healthy subjects using the Spectralis HRA+OCT2. A volumetric projection artifact removal algorithm and customized filters were applied to raw OCTA voxel data. Volume rendering was performed using a workflow on Imaris 9.5 software. Vascular graphs were obtained from angiographic data using the algorithm threshold-loops. Superficial arteries and veins were identified from color fundus photographs and connections between adjacent arteries and veins displayed using the shortest path algorithm. Connective pathway locations were analyzed with cross-sectional OCT and OCTA to determine their course through the superficial vascular complex (SVC) and the deep vascular complex (DVC). Results: Fourteen eyes from seven subjects (mean age: 28 ± 5 years; 3 women) were included in this analysis. One hundred and twenty-six vascular connections were analyzed. In all cases, the shortest path connections between superficial arteries and veins coursed through the DVC. We did not identify shortest path connections confined to the SVC. Conclusions: Volumetric analysis of vascular connectivity supports a predominantly in-series arrangement of blood flow between the SVC and DVC within the human perifoveal macula.publishersversionpublishe

Novel Insights Based on the Anatomy of Henle Fiber Layer

Purpose: The purpose of this study was to identify a precise location of deep capillary plexus (DCP) injury in acute macular neuroretinopathy (AMN) lesions using multimodal imaging. Methods: En face structural optical coherence tomography (OCT) images were manually segmented to delineate outer retinal AMN lesions involving the ellipsoid zone and interdigitation zone. AMN lesion centroid was calculated, and image distortion was applied to correct for Henle fiber layer (HFL) length and orientation. The resulting image was registered with the corresponding en face OCT angiography (OCTA) image segmented at the DCP and structural OCT volume before grading for vascular and structural features, respectively. Results: Thirty-nine AMN lesions from 16 eyes (11 female patients, mean age 34 ± 4 years) were analyzed. After correcting for HFL anatomy, in 62% of AMN lesions, the centroid co-localized with a capillary vortex (pattern 1); flow defects were detected in 33% of lesions (pattern 2); and in 5% of lesions no specific pattern could be identified (pattern 3). The detection of a specific pattern increased after correcting the projection of AMN lesion for HFL anatomy (28% vs. 5%, P = 0.04). Outer nuclear layer thickness was lower in the centroid area in 10 (29%) AMN lesions from 6 patients, all corresponding to lesions fitting pattern 2 (r = 0.78, P < 0.001). Conclusions: AMN lesions might be a result of DCP impairment at the level of the capillary vortex or draining venule. In eyes with AMN, the location of outer retinal changes associated with DCP ischemia appears to be influenced by the length and orientation of HFL.publishersversionpublishe

Intermediate Temperature Fluids Life Tests - Experiments

There are a number of different applications that could use heat pipes or loop heat pipes (LHPs) in the intermediate temperature range of 450 to 725 K (170 to 450 C), including space nuclear power system radiators, fuel cells, and high temperature electronics cooling. Historically, water has been used in heat pipes at temperatures up to about 425 K (150 C). Recent life tests, updated below, demonstrate that titanium/water and Monel/water heat pipes can be used at temperatures up to 550 K (277 C), due to water's favorable transport properties. At temperatures above roughly 570 K (300 C), water is no longer a suitable fluid, due to high vapor pressure and low surface tension as the critical point is approached. At higher temperatures, another working fluid/envelope combination is required, either an organic or halide working fluid. An electromotive force method was used to predict the compatibility of halide working fluids with envelope materials. This procedure was used to reject aluminum and aluminum alloys as envelope materials, due to their high decomposition potential. Titanium and three corrosion resistant superalloys were chosen as envelope materials. Life tests were conducted with these envelopes and six different working fluids: AlBr3, GaCl3, SnCl4, TiCl4, TiBr4, and eutectic diphenyl/diphenyl oxide (Therminol VP-1/Dowtherm A). All of the life tests except for the GaCl3 are ongoing; the GaCl3 was incompatible. As the temperature approaches 725 K (450 C), cesium is a potential heat pipe working fluid. Life tests results are also presented for cesium/Monel 400 and cesium/70-30 copper/nickel heat pipes operating near 750 K (477 C). These materials are not suitable for long term operation, due to copper transport from the condenser to the evaporator

Improved Thin, Flexible Heat Pipes

Flexible heat pipes of an improved type are fabricated as layers of different materials laminated together into vacuum- tight sheets or tapes. In comparison with prior flexible heat pipes, these flexible heat pipes are less susceptible to leakage. Other advantages of these flexible heat pipes, relative to prior flexible heat pipes, include high reliability and greater ease and lower cost of fabrication. Because these heat pipes are very thin, they are highly flexible. When coated on outside surfaces with adhesives, these flexible heat pipes can be applied, like common adhesive tapes, to the surfaces of heat sinks and objects to be cooled, even if those surfaces are curved

Acute Exercise and Appetite-Regulating Hormones in Overweight and Obese Individuals: A Meta-Analysis

In lean individuals, acute aerobic exercise is reported to transiently suppress sensations of appetite, suppress blood concentrations of acylated ghrelin (AG), and increase glucagon-like peptide-1 (GLP-1) and peptide-YY (PYY). Findings in overweight/obese individuals have yet to be synthesised. In this systematic review and meta-analysis, we quantified the effects that acute exercise has on AG and total PYY and GLP-1 in overweight/obese individuals. The potential for body mass index (BMI) to act as a moderator for AG was also explored. Six published studies (73 participants, 78% male, mean BMI: 30.6 kg⋅m −2 ) met the inclusion criteria. Standardised mean differences (SMDs) and standard errors were extracted for AG and total PYY and GLP-1 concentrations in control and exercise trials and synthesised using a random effects meta-analysis model. BMI was the predictor in metaregression for AG. Exercise moderately suppressed AG area-under-the-curve concentrations (pooled SMD: −0.34, 95% CI: −0.53 to −0.15). The magnitude of this reduction was greater for higher mean BMIs (pooled metaregression slope: −0.04 SMD/kg⋅m −2 (95% CI: −0.07 to 0.00)). Trivial SMDs were obtained for total PYY (0.10, 95% CI: −0.13 to 0.31) and GLP-1 (−0.03, 95% CI: −0.18 to 0.13). This indicates that exercise in overweight/obese individuals moderately alters AG in a direction that could be associated with decreased hunger and energy intake. This trial is registered with PROSPERO: CRD42014006265

prevalence and phenotypes of age related macular degeneration in eyes with high myopia

n/