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

NC's Anti-Predatory Lending Law: Doing What It's Supposed To Do: A Reply

We reply to criticisms of our recent study about North Carolina's Anti-Predatory Lending Law reducing predatory loan terms and preserving access to credit (NC's Anti-Predatory Lending Law: Doing What it's Supposed to Do). To examine whether the decline in overall subprime lending in North Carolina, following passage of the predatory lending law, was due to a decline in loans with legitimate terms or to a reduction in loans with abusive terms, we examined specific market segments and market practices using loan level data from the Loan Performance Asset Backed Securities (ABS) database. Our study revealed that, although the total volume of subprime originations in North Carolina declined, the number of home purchase loans was unaffected by the law. Given the robustness of the LP data, we are baffled by the criticism and disappointed by confusion that has arisen over mistaken data interpretation. For reasons discussed in this paper, we stand by our descriptive study and will continue to use LP data in our future work.Technology and Industry, Regulatory Reform

Smelly maps: the digital life of urban smellscapes

Smell has a huge influence over how we perceive places. Despite its importance, smell has been crucially overlooked by urban planners and scientists alike, not least because it is difficult to record and analyze at scale. One of the authors of this paper has ventured out in the urban world and conducted ``smellwalks'' in a variety of cities: participants were exposed to a range of different smellscapes and asked to record their experiences. As a result, smell-related words have been collected and classified, creating the first dictionary for urban smell. Here we explore the possibility of using social media data to reliably map the smells of entire cities. To this end, for both Barcelona and London, we collect geo-referenced picture tags from Flickr and Instagram, and geo-referenced tweets from Twitter. We match those tags and tweets with the words in the smell dictionary. We find that smell-related words are best classified in ten categories. We also find that specific categories (e.g., industry, transport, cleaning) correlate with governmental air quality indicators, adding validity to our study

Hydrocarbon formation core protection and and transportation apparatus

An apparatus for transporting core samples includes an outer tube having an open end and a cover removably mounted to the open end; a core tube slidable into and out ofthe outer tube when the cover is removed from the outer tube; and a stabilizing structure between the core tube and the outer tube, the stabilizing structure supporting the core tube within the outer tube with the core tube spaced from contact with an inner wall ofthe outer tube

Reduced abrasion drilling fluid

A reduced abrasion drilling fluid system and method of drilling a borehole by circulating the reduced abrasion drilling fluid through the borehole is disclosed. The reduced abrasion drilling fluid comprises a drilling fluid, a first additive and a weighting agent, wherein the weighting agent has a particle size of at least 90% by volume less than 50 um

Exploratory characterization of volcanic ash sourced from Uganda as a pozzolanic material in portland cement concrete

The need for alternative cementing materials to ordinary Portland cement (OPC) has promoted characterization research on pozzolana as an important ingredient in cement production. In Uganda, natural pozzolana application in cement production is done by only two producers of Portland cement and at a small scale due to capacity constraints. The capacity constraints, together with other technological issues, continue to hinder realization of the cost reduction and improved quality benefits attributed to the use of pozzolana as a mineral admixture in Portland cement concrete. There is high abundance of natural pozzolana in Uganda in the form of volcanic ash/tuffs which, if adequately characterized, can facilitate production of different cementing materials and increase output from the various players in the cement production industry in Uganda. This paper reviews methods of pozzolana characterisation and presents preliminary research findings on application of natural pozzolana sourced from Uganda in development of Portland cement concrete. Samples collected from two different deposits in the western region of Uganda were prepared and subjected to chemical analysis and tests on compressive strength, flexural strength and flow-ability. The preliminary findings are indicative of good quality pozzolanic materials that can be applied as mineral admixture in production of Portland cement concrete

The Digital Life of Walkable Streets

Walkability has many health, environmental, and economic benefits. That is why web and mobile services have been offering ways of computing walkability scores of individual street segments. Those scores are generally computed from survey data and manual counting (of even trees). However, that is costly, owing to the high time, effort, and financial costs. To partly automate the computation of those scores, we explore the possibility of using the social media data of Flickr and Foursquare to automatically identify safe and walkable streets. We find that unsafe streets tend to be photographed during the day, while walkable streets are tagged with walkability-related keywords. These results open up practical opportunities (for, e.g., room booking services, urban route recommenders, and real-estate sites) and have theoretical implications for researchers who might resort to the use social media data to tackle previously unanswered questions in the area of walkability.Comment: 10 pages, 7 figures, Proceedings of International World Wide Web Conference (WWW 2015