A Comparison Between Optical Coherence Tomography Angiography and Fluorescein Angiography for the Imaging of Type 1 Neovascularization.

Purpose: To determine the sensitivity of the combination of optical coherence tomography angiography (OCTA) and structural optical coherence tomography (OCT) for detecting type 1 neovascularization (NV) and to determine significant factors that preclude visualization of type 1 NV using OCTA. Methods: Multicenter, retrospective cohort study of 115 eyes from 100 patients with type 1 NV. A retrospective review of fluorescein (FA), OCT, and OCTA imaging was performed on a consecutive series of eyes with type 1 NV from five institutions. Unmasked graders utilized FA and structural OCT data to determine the diagnosis of type 1 NV. Masked graders evaluated FA data alone, en face OCTA data alone and combined en face OCTA and structural OCT data to determine the presence of type 1 NV. Sensitivity analyses were performed using combined FA and OCT data as the reference standard. Results: A total of 105 eyes were diagnosed with type 1 NV using the reference. Of these, 90 (85.7%) could be detected using en face OCTA and structural OCT. The sensitivities of FA data alone and en face OCTA data alone for visualizing type 1 NV were the same (66.7%). Significant factors that precluded visualization of NV using en face OCTA included the height of pigment epithelial detachment, low signal strength, and treatment-naïve disease (P \u3c 0.05, respectively). Conclusions: En face OCTA and structural OCT showed better detection of type 1 NV than either FA alone or en face OCTA alone. Combining en face OCTA and structural OCT information may therefore be a useful way to noninvasively diagnose and monitor the treatment of type 1 NV

The Scaling Window of the 2-SAT Transition

We consider the random 2-satisfiability problem, in which each instance is a formula that is the conjunction of m clauses of the form (x or y), chosen uniformly at random from among all 2-clauses on n Boolean variables and their negations. As m and n tend to infinity in the ratio m/n --> alpha, the problem is known to have a phase transition at alpha_c = 1, below which the probability that the formula is satisfiable tends to one and above which it tends to zero. We determine the finite-size scaling about this transition, namely the scaling of the maximal window W(n,delta) = (alpha_-(n,delta),alpha_+(n,delta)) such that the probability of satisfiability is greater than 1-delta for alpha < alpha_- and is less than delta for alpha > alpha_+. We show that W(n,delta)=(1-Theta(n^{-1/3}),1+Theta(n^{-1/3})), where the constants implicit in Theta depend on delta. We also determine the rates at which the probability of satisfiability approaches one and zero at the boundaries of the window. Namely, for m=(1+epsilon)n, where epsilon may depend on n as long as |epsilon| is sufficiently small and |epsilon|*n^(1/3) is sufficiently large, we show that the probability of satisfiability decays like exp(-Theta(n*epsilon^3)) above the window, and goes to one like 1-Theta(1/(n*|epsilon|^3)) below the window. We prove these results by defining an order parameter for the transition and establishing its scaling behavior in n both inside and outside the window. Using this order parameter, we prove that the 2-SAT phase transition is continuous with an order parameter critical exponent of 1. We also determine the values of two other critical exponents, showing that the exponents of 2-SAT are identical to those of the random graph.Comment: 57 pages. This version updates some reference

Dégénérescence kystique maculaire de la couche nucléaire interne chez des patients atteint de glaucome

International audiencePurpose: The study aimed to detect and describe glaucoma-related pseudocystic abnormalities at the internal nuclear layer (INL) of the macula using OCT, in relation with visual field defects and other clinical data. Patients and methods: Primary open-angle glaucoma patients presenting for a follow-up visit were consecutively included over 5 months and underwent clinical examination, OCT imaging, and central 10-2 visual field testing. OCT measures included the thickness of the peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC), together with an analysis of B-Scans and en-face images. All data provided by OCT were analyzed and compared with the visual field testing. Results: Fourteen patients out of 216 showed pseudocysts in the INL of the macula. These cysts were hyporeflective, fusiform, and of variable size (15 to 25 μm) and were always associated with a thinning of both the RNFL and GCC. En-face OCT showed evidence of a distribution of cysts in the macular region, based on the appearance of numerous, dense hyporeflective pits whose localization matched precisely with the vision loss as assessed by central 10-2 visual field testing. No other correlations were found. Discussion: Pseudocysts of the internal nuclear layer of the macular region are found in some cases of chronic glaucoma. Their presence is always associated with a scotoma in the visual field and appear to constitute a marker for glaucoma progression. Glaucoma-related central pseudocysts could result from Müller cell changes, excitotoxicity, and/or trans-synaptic retrograde degeneration. The presence of pseudocysts could be a marker of a particular subpopulation whose features remain to be determined

Weak Balance in Random Signed Graphs

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