Ocular hypertension in myopia: analysis of contrast sensitivity

Purpose: we evaluated the evolution of contrast sensitivity reduction in patients affected by ocular hypertension and glaucoma, with low to moderate myopia. We also evaluated the relationship between contrast sensitivity and mean deviation of visual field. Material and methods: 158 patients (316 eyes), aged between 38 and 57 years old, were enrolled and divided into 4 groups: emmetropes, myopes, myopes with ocular hypertension (IOP≥21 ±2 mmHg), myopes with glaucoma. All patients underwent anamnestic and complete eye evaluation, tonometric curves with Goldmann’s applanation tonometer, cup/disc ratio evaluation, gonioscopy by Goldmann’s three-mirrors lens, automated perimetry (Humphrey 30-2 full-threshold test) and contrast sensitivity evaluation by Pelli-Robson charts. A contrast sensitivity under 1,8 Logarithm of the Minimum Angle of Resolution (LogMAR) was considered abnormal. Results: contrast sensitivity was reduced in the group of myopes with ocular hypertension (1,788 LogMAR) and in the group of myopes with glaucoma (1,743 LogMAR), while it was preserved in the group of myopes (2,069 LogMAR) and in the group of emmetropes (1,990 LogMAR). We also found a strong correlation between contrast sensitivity reduction and mean deviation of visual fields in myopes with glaucoma (coefficient relation = 0.86) and in myopes with ocular hypertension (coefficient relation = 0.78). Conclusions: the contrast sensitivity assessment performed by the Pelli-Robson test should be performed in all patients with middle-grade myopia, ocular hypertension and optic disc suspected for glaucoma, as it may be useful in the early diagnosis of the disease. Introduction Contrast can be defined as the ability of the eye to discriminate differences in luminance between the stimulus and the background. The sensitivity to contrast is represented by the inverse of the minimal contrast necessary to make an object visible; the lower the contrast the greater the sensitivity, and the other way around. Contrast sensitivity is a fundamental aspect of vision together with visual acuity: the latter defines the smallest spatial detail that the subject manages to discriminate under optimal conditions, but it only provides information about the size of the stimulus that the eye is capable to perceive; instead, the evaluation of contrast sensitivity provides information not obtainable with only the measurement of visual acuity, as it establishes the minimum difference in luminance that must be present between the stimulus and its background so that the retina is adequately stimulated to perceive the stimulus itself. The clinical methods of examining contrast sensitivity (lattices, luminance gradients, variable-contrast optotypic tables and lowcontrast optotypic tables) relate the two parameters on which the ability to distinctly perceive an object depends, namely the different luminance degree of the two adjacent areas and the spatial frequency, which is linked to the size of the object. The measurement of contrast sensitivity becomes valuable in the diagnosis and follow up of some important eye conditions such as glaucoma. Studies show that contrast sensitivity can be related to data obtained with the visual perimetry, especially with the perimetric damage of the central area and of the optic nerve head

On the stability of the standard Riemann semigroup

We consider the dependence of the entropic solution of a hyperbolic system of conservation laws {ut + f(u)x = 0, u(0, \ub7) = u0 on the flux function f. We prove that the solution is Lipschitz continuous w.r.t, the C0 norm of the derivative of the perturbation of f. We apply this result to prove the convergence of the solution of the relativistic Euler equation to the classical limit

The role of environmental sustainability in the relocation choices of MNEs: Back to the home country or welcome in a new host country?

This study investigates how firms' awareness of environmental sustainability affects the revision of their internationalization strategies. Combining Stakeholder and Signalling theories, we argue that firms concerned with environmental sustainability have a higher propensity to return to their home country when confronted with the need to relocate foreign manufacturing subsidiaries, in order to match Corporate Social Responsibility (CSR) stakeholder expectations and enhance the effectiveness of sustainable disclosure endeavours. We also argue that the home country's environmental policy stringency, reflecting a stronger pressure by stakeholders and a higher need for effective signals, positively moderates the relationship between the firm environmental sustainability concern and the likelihood to move back home. The empirical analysis conducted on a sample of 150 relocations performed across European nations in 2002–2016 reveals that MNEs signalling their CSR are more likely to backshore only in case of rigid environmental laws, which are perceived as an opportunity to align with CSR stakeholder expectations and to amplify the benefits of disclosing the shortening of their global value chain

Agrobiodiversidade no Acre: um exemplo da agricultura dos Kaxinawá do Rio Humaitá.

A agricultura indígena encontrada atualmente no estado do Acre representa muitos aspectos dos sistemas agrícolas que se consolidaram nesse centro de origem. O estudo dessa agricultura nos ajuda a compreender como a biodiversidade agrícola foi criada e manejada no ambiente amazônico, como sugerido por estudos botânicos, e como esses sistemas podem ser conciliados com os registros arqueológicos existentes na região. Diversidade linguística e agrícola do Acre; Centro de Origem da Amazônia Ocidental; O Roçado verdadeiro Kaxinawá de Harlan; O roçado de praia na TIRH.bitstream/item/209232/1/Agrobiodiversidade-no-Acre-2019.pd

A taxonomic study of Jacquemontia evolvuloides (Moric.) Meisn. and related species (Convolvulaceae).

Made available in DSpace on 2018-01-09T16:14:10Z (GMT). No. of bitstreams: 1 a2017n2a60.pdf: 6004543 bytes, checksum: 622a8fd20f952479c74b285593d34289 (MD5) Previous issue date: 2018-01-09bitstream/item/170613/1/a2017n2a6-0.pd

Geostructural and geomechanical study of the piastrone quarry (Seravezza, Italy) supported by photogrammetry to assess failure mode

The use of non-contact-techniques for rock mass characterization has been growing significantly over the last decade. However, their application to stability assessment of ornamental stone has not yet received much attention from researchers. This study utilizes rock mass data both in terms of slope orientations and degree of fracturing obtained from a point cloud, a set of three-dimensional (3D) points representing a rock mass surface, to (1) investigate the influence of geostructures at different scales and (2) assess quarry stability by determining areas susceptible to different failure types. Multi-resolution point clouds are obtained through several photogrammetric survey techniques to identify important structural elements of the site. By integrating orientation data of discontinuity planes, obtained with a traditional survey, and of traces, outlined on point clouds, several joint sets were identified. Kinematic tests revealed various potential failure modes of the rock slope. Moreover, an analysis of the influence of the discontinuity strength determined by the presence of rock bridges was carried out. The study revealed that the strength of the quarry face is governed by the presence of rock bridges that act to improve the stability condition of the rock fronts

The vaulting system of the Palatine Chapel: the Aachen Cathedral world heritage site documentation project.

As part of a comprehensive survey and modelling project involving the Aachen Cathedral, this paper focuses on its oldest part, the Palatine Chapel, a domed octagonal hall supported by eight piers and enveloped by a sixteen-sided outer wall. Working on the data collected during an extensive 3D capturing campaign conducted between 2022 and 2023, this paper will focus on the conic vaults covering the ambulacrum of the 1st floor that represent quite a peculiar architectural and structural solution considering the VIII/IX century building know-how. In this framework, the Chapel's 3D point cloud has been analysed to extract the main 2D generative elements of the conic surfaces and then construct the corresponding 3D geometric models. These outputs have been compared against the captured point cloud to assess the differences between the actual vault data and the reconstructed ideal conic shapes. Finally, the method used to unfold the vaults' surfaces and create high-resolution ortho-images has been displayed