Presence Of DME Research Articles

Assessment of Baseline Ultrawidefield Fluorescein Angiographic Quantitative Leakage Parameters with Ultrawidefield Fundus Features and Clinical Parameters in Diabetic Retinopathy in Protocol AA

PurposeEvaluate quantitative leakage parameters on ultra-widefield fluorescein angiography (UWF-FA) images and explore their association with Diabetic Retinopathy Severity Scale (DRSS), predominantly peripheral lesions (PPLs), visual acuity, and clinical characteristics. DesignA post-hoc analysis of baseline UWF-FA images in the DRCR Retina Network observational study Protocol AA. ParticipantsN = 575 eyes from 384 adults across 38 sites in the US and Canada with gradable UWF-FA. MethodsA machine learning-enhanced feature extraction platform provided initial leakage segmentation of UWF-FA images sequentially reviewed and corrected by two certified readers for segmentation accuracy. UWF-FA leakage was measured in five retinal zones: panretinal (whole retina), central macular (3-disc diameter fovea-centered circle), posterior pole (6-disc diameter fovea-centered circle), peripheral (outside 6-disc diameter circle) and widefield far peripheral (outside 9-disc diameter circle); associations with clinical factors were evaluated with marginal beta regression models. Main Outcome MeasuresUWF-FA leakage index, calculated as the area with leakage divided by the analyzable retinal area. ResultsThe mean quantitative leakage index was 3.5% for panretinal, 6.6% for macular, 4.8% for posterior pole, 3.3% for peripheral and 2.8% for wide-field far peripheral retinal zones. Panretinal leakage was associated with DRSS (mean 2.2% for no to mild NPDR, 3.4% for moderate NPDR, 4.2% for moderately severe NPDR, 4.8% for severe NPDR and 5.1% for PDR; P<.001), HbA1c (3.2% for HbA1c <8% vs. 3.8% for HbA1c ≥8%; P=.01 for continuous HbA1c), visual acuity (3.3% for 20/25 or better vs. 4.7% for 20/32 or worse; continuous P<.001), and UWF-FA-PPL types of IRMA (4.3% vs. 3.3%; P=.005) or NVE (5.7% vs. 3.4%; P=.003). DRSS was also statistically significant for leakage within all retinal zones (P<.001); eyes with non-central DME versus no DME had higher mean leakage in the central macular (11.2% vs. 5.9%; P=0.005) and posterior pole regions (9.2% vs. 4.2%; P=.002). ConclusionQuantitative UWF-FA leakage analysis identified associations between leakage and DRSS, visual acuity, and presence of DME. In the future, quantitative UWF-FA leakage parameters may be explored as potential biomarkers for disease progression risk.

Divalent Titanium via Reductive N-C Coupling of a TiIV Nitrido with π-Acids.

The nitrido-ate complex [(PN)2Ti(N){μ2-K(OEt2)}]2 (1) (PN-=(N-(2-PiPr2-4-methylphenyl)-2,4,6-Me3C6H2) reductively couples CO and isocyanides in the presence of DME or cryptand (Kryptofix222), to form rare, five-coordinate TiII complexes having a linear cumulene motif, [K(L)][(PN)2Ti(NCE)] (E=O, L=Kryptofix222, (2); E=NAd, L=3 DME, (3); E=NtBu, L=3 DME, (4); E=NAd, L=Kryptofix222, (5)). Oxidation of 2-5 with [Fc][OTf] afforded an isostructural TiIII center containing a neutral cumulene, [(PN)2Ti(NCE)] (E=O, (6); E=NAd (7), NtBu (8)) and characterization by CW X-band EPR spectroscopy, revealed unpaired electron to be metal centric. Moreover, 1e- reduction of 6 and 7 in the presence of Kryptofix222cleanly reformed corresponding discrete TiII complexes 2 and 5, which were further characterized by solution magnetization measurements and high-frequency and -field EPR (HFEPR) spectroscopy. Furthermore, oxidation of 7 with [Fc*][B(C6F5)4] resulted in a ligand disproportionated TiIV complex having transoid carbodiimides, [(PN)2Ti(NCNAd)2] (9). Comparison of spectroscopic, structural, and computational data for the divalent, trivalent, and tetravalent systems, including their 15N enriched isotopomers demonstrate these cumulenes to decrease in order of backbonding as TiII→TiIII→TiIV and increasing order of π-donation as TiII→TiIII→TiIV, thus displaying more covalency in TiIII species. Lastly, we show a synthetic cycle whereby complex 1 can deliver an N-atom to CO and CNAd.

Predictive Assessment of Quantitative Ultra-Widefield Angiographic Features for Future Need for Anti-VEGF Therapy in Diabetic Eye Disease

The objective of this study was to identify biomarkers that predict a future need for anti-VEGF therapy in diabetic retinopathy (DR). Eyes with DR that underwent ultra-widefield angiography (UWFA) and had at least a 1 year follow-up were grouped based on future anti-VEGF treatment requirements: (1) not requiring treatment, (2) immediate treatment (within 3 months of UWFA), and (3) delayed treatment (after 3 months of UWFA). Quantitative UWFA features and clinical factors were evaluated. Random forest models were built to differentiate eyes requiring immediate and delayed treatment from the eyes not requiring treatment. A total of 173 eyes were included. The mean follow-up was 22 (range: 11–43) months. The macular leakage index, panretinal leakage index, presence of DME, and visual acuity were significantly different in eyes requiring immediate (n = 38) and delayed (n = 34) treatment compared to eyes not requiring treatment (n = 101). Random forest model differentiating eyes requiring immediate treatment from eyes not requiring treatment demonstrated an AUC of 0.91 ± 0.07. Quantitative angiographic features have potential as important predictive biomarkers of a future need for anti-VEGF therapy in DR and may serve to guide the frequency of a follow-up.

Peripapillary Retinal Nerve Fiber Layer Changes in Patients with Diabetes Mellitus: A Case-control Study

ABSTRACT Purpose To evaluate peripapillary retinal nerve fiber layer (RNFL) changes in patients with diabetes mellitus (DM) and compare them with those of normal population. In addition, this study aims to determine potential factors, affecting RNFL changes in patients with DM. Methods Participants in this study were 107 patients (211 eyes) with DM and 100 healthy controls (200 eyes). Diabetic patients were further classified into four groups depending on severity of diabetic retinopathy (no retinopathy, mild, moderate, severe nonproliferative diabetic retinopathy, and proliferative diabetic retinopathy, while presence of macular edema was also assessed. All participants underwent spectral-domain optical coherence tomography (SD-OCT) to measure RNFL thickness, while demographic and clinical characteristics of the participants were also recorded. Results Patients with DM with or without DR presented significantly decreased peripapillary RNFL thickness in all quadrants. In the diabetic group, the multivariate analysis showed a significant association between decreased average RNFL thickness and increased HbA1c (p < 0.001), longer DM duration (p = 0.007), and more severe diabetic retinopathy status (p = 0.016), while presence of DME, age, gender, hypertension, and hyperlipidemia were not found to be associated with RNFL thickness decrease. Conclusion Diabetes mellitus seems to affect RNFL thickness, suggesting that early neurodegenerative changes may occur, potentially before microvascular alterations. Since duration of disease, DR severity, and HbA1c levels were associated with RNFL thinning, modifying glycemic control seems to be important to potentially prevent the development of DM complications.

Transition‐Metal‐Free Trifluoromethylation of Benzyl Bromides Using Trifluoromethyltrimethylsilane and CsF in 1,2‐Dimethoxyethane

AbstractAn SN2‐type trifluoromethylation of benzyl halides under transition‐metal‐free conditions has been developed using trifluoromethyltrimethylsilane (CF3SiMe3, Ruppert−Prakash reagent) and CsF in 1,2‐dimethoxyethane (DME). Under the developed reaction conditions, the in situ generated trifluoromethyl anion (CF3−) overcame the instability and displayed enhanced nucleophilicity in the presence of DME. This method provides an efficient approach for the generation of various (2,2,2‐trifluoroethyl)arenes such as those bearing alkyl, alkoxy, halo (F, Cl, and Br) and trifluoromethyl groups on the benzene rings.

51-OR: Medios—A Smartphone-Based Artificial Intelligence Algorithm in Screening for Diabetic Retinopathy

Background: Pupil dilatation, access to ophthalmologists, size and cost of fundus cameras, and network connectivity issues are barriers to diabetic retinopathy (DR) screening in primary care. This makes artificial intelligence a potential alternative in DR screening. This study aims to evaluate the performance of an offline AI algorithm - Medios in DR Screening using non mydriatic retinal images taken from the smartphone based Remidio Fundus on Phone (NM-FOP) retinal camera. Methods: Non mydriatic retinal images from 900 patients with diabetes were captured prospectively with the Remidio NM FOP camera at Diacon Hospital, Bangalore, India. The images were graded by 5 ophthalmologists as per the International Diabetic Retinopathy Classification System and the majority diagnosis was considered as the ground truth. Two images [posterior pole (macula centered), nasal field] were captured per eye for each patient, and were analyzed offline on-device using the Medios AI. The diagnosis of Medios AI was compared to that of the ophthalmologist. Results: DR was present in 252 patients. Performance of the AI for referable DR (Moderate NPDR or worse, or presence of DME) was - Sensitivity 93% (95% CI 91.3%-94.7%), Specificity: 92.5% (95% CI 90.8%-94.2%). Performance of the AI for all DR (Mild NPDR or worse, or presence of DME) was - Sensitivity: 83.3% (95% CI 80.9%-85.7%), Specificity: 95.5% (95% CI 94.1%-96.8%). Sensitivity for sight threatening DR (STDR) [severe NPDR, proliferative DR (PDR) or presence of DME] was 95.2% (95% CI 88.2%-98.6%). The 3 PDRs missed by the AI were post laser with no active changes visible. This is a common exclusion criteria in other studies, and when excluded, the sensitivity for STDR was found to be 98.7%. Conclusion: This is one of the largest studies evaluating the performance of AI using non mydriatic retinal images offline. The Medios AI algorithm’s sensitivity and specificity exceeds the FDA mandated superiority end point and can be used for DR screening. Disclosure B. Sosale: None. A.R. Sosale: None. H. Murthy: None. S. Narayana: None. U. Sharma: None. S.G.V. Gowda: None. M. Naveenam: None.

Evaluation of choroidal thickness in different stages of diabetic retinopathy

Purpose: to assess changes of choroidal thickness (CT) in diabetic patients in different stages of diabetic retinopathy and diabetic macular edema using spectral domain optical coherence tomography. Patients and methods: One hundred and sixty three subjects were enrolled: 113 diabetic patients (186 eyes) and 50 normal individuals as controls. Eyes were divided into two groups according to age; group A from 35 to 50 years and group B from 51 to 65 years. Both groups classified according to retinopathy grade: DR1 (no DR), DR2 (mild- moderate nonproliferative diabetic retinopathy (NPDR)), DR3 (severe NPDR), DR4 (untreated proliferative diabetic retinopathy (PDR)) and DR5 (previously treated PDR). All participants underwent full ophthalmic examination, stereoscopic color fundus photography, and spectral domain optical coherence tomography (RS-3000; Nidek). Spectral domain optical coherence tomography examination consisted of linear scans, 6 mm in length, centered onto the fovea, and macula multi scans. Choroidal thickness was measured manually at the fovea and at 500, 1000, and 1500 um distance along all scans in the macula. Results: Mean age was not significantly different between patients with diabetes and controls. In the macular area, CT was significantly lower in the nasal quadrant versus all other quadrants (P, 0.0001), in both groups. No significant CT difference was found between controls and diabetic eyes without detectable DR. Diabetic macular edema did not influence CT. In early NPDR (mild and moderate) and treated PDR the mean choroidal thickness was significantly decreased than control. In severe NPDR and treated PDR, the mean subfoveal choroidal thickness was not different than control. There was a statistically significant increase in choroidal thickness in PDR when compared with the mild NPDR group (P=0.027). DME was associated with a non-statistically significant increase in choroidal thickness compared with eyes without DME (P=0.13). Conclusion: Choroidal thickness is reduced in diabetic eyes. Subfoveal choroidal thickness increased with the severity of diabetic retinopathy but showed no statistically significant association with the presence of DME. Spectral domain optical coherence tomography clearly confirms in vivo previously reported histopathologic observations. The role of choroid in the pathophysiology of DR needs to be adequately investigated.

Potassium and Lithium Complexes with Monodeprotonated, Dearomatized PNP and PNCNHC Pincer-Type Ligands

The reaction of 2,6-bis(di-tert-butylphosphinomethyl)pyridine (tBuPNtBuP) with 1 molar equiv of KCH2C6H5 or LiCH2SiMe3 gave M(tBuP*NatBuP) (M = K, Li; P* = vinylic P donor, tBuP = PtBu2, Na = anionic amido N donor) after monodeprotonation of the α-lutidinyl-CH2 and concomitant dearomatization of the heterocycle. Evidence is provided that the anion tBuP*NatBuP may exist as Z- and E-isomers, interconvertible by rotation about the Cα-N–Cα-P exocyclic formal double bond. Thus, the two isomers of K(tBuP*NatBuP), i.e., [K{(Z)-(tBuP*NatBuP-κP*,κNa,κP)}(THF)], 1-Z·(THF), and [K{(E)-(tBuP*NatBuP-κNa,κP)}(THF)], 1-E·(THF), cocrystallized from THF in a 4:1 ratio. However, in the presence of DME, the isomerically pure [K{(E)-(tBuP*NatBuP-κNa,κP)}(DME)2], 1-E·2(DME), was crystallized. The α-picolinyl-CH2 moiety in RPNCNHC (N = substituted 2-picoline, RP = PCy2, R = Cy; RP = PtBu2, R = tBu; CNHC = N-heterocyclic carbene) was similarly deprotonated with concomitant dearomatization using LiN(SiMe3)2. This afforded the co...

Redistribution reactions of heteroleptic barium iodide derivatives: Synthesis and structures of trans-BaI 2(DME)(triglyme), cis-BaI 2(DME)(tetraglyme) and [Ba(tetraglyme) 2]I 2 · C 7H 8

The reaction between BaI 2 · 2H 2O and NaHFIP [HFIP = OCH(CF 3) 2] in a 1:1 stoichiometry gave the heterometallic compound NaBaI 2(HFIP)(H 2O)(THF) 0.5 ( 1). Attempts to recrystallize 1 in the presence of N- or O-donor ligands lead to redistribution reactions. Barium iodide adducts such as BaI 2(DME) 3 ( 2), trans-BaI 2(DME)(triglyme) ( 3) and cis-BaI 2(DME)(tetraglyme) ( 4) were isolated with DME as solvent. A similar behavior was observed for the reaction between BaI 2 · 2H 2O and NaTFA (TFA = O 2CCF 3) in a 1:1 stoichiometry in THF, and [Ba(tetraglyme) 2]I 2 · C 7H 8 ( 6) was isolated in the presence of excess tetraglyme. All compounds have been characterized by elemental analysis, IR and 1H NMR as well as single crystal X-ray studies for 3, 4 and 6. Compounds 3 and 4 are covalent adducts with eight- and nine-coordinate barium, respectively. Compound 6 is an ionic compound where two tetraglyme ligands wrap the 10-coordinate barium cation in a helical fashion. The presence of DME actually allows the coordination number of barium in the mixed-ligand adducts 3 and 4 to be tuned. The average Ba–O bond lengths (2.80 for 3 to 2.87 Å for 6) reflect the coordination number of the metal. The same observation is valid for the average Ba–I bond distance, 3.442 for 3 vs. 3.536 Å for 4.

Formation of Calcium–Carbon Bonds From a Lewis Acid-Base Reaction of Calcium Bis[bis(trimethylsilyl)amide] and Tris(trimethylsilylmethyl)alane

Treatment of calcium bis[bis(trimethylsilyl)amide] with two equivalents of tris(trimethylsilylmethyl)alane yields (Me3SiCH2)2Al–N(SiMe3)2 (1) and the dimer [(Me3Si)2N–Ca(μ–CH2SiMe3)2Al(CH2SiMe3)2]2 (2). The five-coordinate bridging carbon atoms show Ca–C bond lengths of 264 and 268 pm. A similar reaction with calcium bis[bis(trimethylsilyl)phosphanide] gives the dimer [(Me3SiCH2)2Al–P(SiMe3)2]2 (3) with crystallographic C2 symmetry. A calcium-containing species is not isolable, however, in the presence of DME – ether cleavage reactions and the formation of the centrosymmetric dimer [(Me3SiCH2)2Al–OCH2CH2OMe]2 (4) are observed. The central moiety is an Al2O2 cycle with fivefold coordinated aluminium centers.

Formation of Calcium–Carbon Bonds From a Lewis Acid-Base Reaction of Calcium Bis[bis(trimethylsilyl)amide] and Tris(trimethylsilylmethyl)alane

Treatment of calcium bis[bis(trimethylsilyl)amide] with two equivalents of tris(trimethylsilylmethyl)alane yields (Me3SiCH2)2Al–N(SiMe3)2 (1) and the dimer [(Me3Si)2N–Ca(μ–CH2SiMe3)2Al(CH2SiMe3)2]2 (2). The five-coordinate bridging carbon atoms show Ca–C bond lengths of 264 and 268 pm. A similar reaction with calcium bis[bis(trimethylsilyl)phosphanide] gives the dimer [(Me3SiCH2)2Al–P(SiMe3)2]2 (3) with crystallographic C2 symmetry. A calcium-containing species is not isolable, however, in the presence of DME – ether cleavage reactions and the formation of the centrosymmetric dimer [(Me3SiCH2)2Al–OCH2CH2OMe]2 (4) are observed. The central moiety is an Al2O2 cycle with fivefold coordinated aluminium centers.

A General Route to Labile Niobium and Tantalum d0 Monoimides. Discussion of Metal−Nitrogen Vibrational Modes

Reaction of TaCl5 with 2 equiv of an amine in the presence of sodium silicate and pyridine affords Ta(NR)Cl3(py)2 in good yield. Reaction of NbCl5 with ZnCl2 followed by addition of an amine RNH2 and pyridine affords M(NR)Cl3(dme) (dme is 1,2-dimethoxyethane). For niobium this reaction proceeds smoothly regardless of the amine but is ineffective with tantalum and alkyl amines. An alternative route involves reaction of TaCl5 with 3 equiv of RNH2 to form [RNH3]2[Ta(NR)Cl5], followed by reaction of this salt with ZnCl2 in the presence of dme. The molecular structure of Nb(NtBu)Cl3(dme) (formula C8H19Cl3NNbO2) was determined by X-ray crystallography (monoclinic space group Cc with a = 30.565(4) A, b = 7.2406(13) A, c = 13.915(2) A, β = 90.626(7)°, V = 3079.4(8) A3, Z = 8). The Nb−N bond length is 1.72 A with a Nb−N−C bond angle of 177° in a distorted octahedral structure. In order to characterize the M−N stretching frequencies in these compounds, IR data for each compound are compared with calculated stretchi...

New titanium and zirconium sandwich and half-sandwich complexes containing the C 5Me 4CH 2CH 2CHCH 2(Cp =) ligand

The syntheses and characterization of new titanium and zirconium derivatives of the C 5Me 4CH 2CH 2CH 2(Cp +=) ligand are described. Reaction of LiCp = with ZrCl 4 in diethyl ether afforded the half-sandwich derivative [Zr 2( n-Cp 2)Cl 4( μ-Cl) 2] which is a precursor to the mixed-ring zirconocenes [Zr( n-Cp =( n-C 5H 5)Cl 2] and [Zr( n-Cp =) ( n-C 5Me 5)Cl 2]. Reaction of LiCp = with ZrCl 4 in toluene followed by crystallization in the presence of dme (1,2-dimethoxyethane) gave the unusual complex [Zr 2( n-Cp =) 2( μ-Cl) 3Li(dme)] (X-ray structure) in which a {Zr 2( n-Cp =) 2Cl 4( μm-Cl) 3} − moiety formally acts as a tetradentate ligand to a {Li(dme)} + fragment. Treatment of [TiCl 3(thf) 3] with LiCp = followed by HCL gave the half-sandwich titanium derivative [Ti( n-Cp =)Cl 3] and addition of one equivalent of LiCp = to a solution of [Ti(NBu t)Cl 2(4-NC 5H 4Bu t) 2] gave the corresponding imido complex [i( n-Cp =)(NBu t)Cl(4-NC 5H 4 Bu t)] in quantitative yield.

Stereochemistry of the C 3 addition of 1-lithio 1,1-bis methylselenoalkanes to methyl cyclohexenones

The presence of DME or HMPT allows the C 3 regio and stereoselective introduction of 1,1-bis methylselenoalkanes to methyl cyclohexenones. The resulting compounds have been stereoselective transformed to 3-ethyl methyl cyclohexanones

Lanthanide shift reagents. III. chemical exchange of substrates and fod ligands

The chemical exchange effects in the proton NMR spectra of solutions containing a lanthanide shift reagent Ln(fod) 3 and the substrate 1,2-dimethoxyethane (DME) were studied. The dependence of the exchange rate of DME molecules on the substrate concentration provided information on the mechanisms of this exchange process. With the aid of this information a quantitative analysis of the reactions involved in this exchange could be given. The influence of temperature and DME concentration on the exchange rates of DME molecules and fod ligands in mixtures of La(fod) 3 and Pr(fod) 3 was analyzed. For comparison, mixtures of other Ln(fod) 3 complexes in the presence of DME were also studied.