Search results for "Optometry"
showing 10 items of 812 documents
Inflammatory cytokines decrease viability and alter ganglioside profile in retinal pigment epithelium cells
2013
Purpose Early stages of Age related Macular Degeneration (AMD) are characterized by dysfunction and degeneration of the retinal pigment epithelium (RPE) cells, which participate in the death of the overlying photoreceptors ultimately leading to loss of vision. Gangliosides (GG) make a wide and heterogeneous family of sialic-acid-containing glycosphingolipids, composed of a sugar chain branched on a ceramide. They are major components of cellular membranes, particularly abundant in the brain and nervous tissue, including retina. While their developmental and neuroprotective actions have been demonstrated, their precise role in retina’s function and its pathologies is still poorly understood.…
Nanostructuring Biopolymers for Improved Food Quality and Safety
2018
Abstract Food-grade biopolymers, apart from their inherent nutritional properties, can be tailored designed for improving food quality and safety, either serving as delivery vehicles for bioactive molecules, or as novel packaging components, not only improving the transport properties of biobased packaging structures, but also imparting active antibacterial and antiviral properties. In this chapter, the potential of different food-grade biopolymers (mainly proteins and carbohydrates but also some biopolyesters) to serve as encapsulating matrices for the protection of sensitive bioactives or as nanostructured packaging layers to improve transport properties and control the growth of pathogen…
Suprachoroidal Bleeding After XEN Gel Implantation
2017
Purpose To report for the first time a clinical case of suprachoroidal bleeding after XEN45 gel implantation. Observations A 84-year old female patient with pseudoexfoliation glaucoma with intraocular pressure (IOP) (20 mm Hg) above target despite maximal IOP-lowering therapy was scheduled for XEN45 gel implantation. The XEN45 gel implantation went without complications and was properly placed in the anterior chamber and beneath the conjunctiva. On the first postoperative day, the patient presented with an IOP of 4 mm Hg, a functioning bleb and a deep anterior chamber. On the second day she developed suprachoroidal bleeding. A wait and see strategy was followed and the patient monitored ste…
Tributo al professor Miguel F. Refojo, PhD, DSc (1928---2016)
2016
[Excerpt] July 21, 2016, Professor Miguel F. Refojo passed away at the age of 88 in Needham (Massachusetts). Saying that Miguel was one of the most renowned Spanish scientists of the second half of the XXth Century does not resembles its actual scientific size. Indeed, Miguel (or “Migüel” as most of his American friends pronounced his name) was a World Class scientist and inventor that will be forever linked to the advances in polymer science applied to the ophthalmic environment. His contributions in the biomedical field start “officially” in 1967 according to the National Library of Medline database (Pubmed-Medline). [...]
Effect of cylinder power and axis changes on vision in astigmatic participants: a comment [Letter]
2019
Laura Remón,1 Walter D Furlan21Departamento de Física Aplicada, Universidad de Zaragoza, 50009 Zaragoza, Spain; 2Departamento de Óptica y Optometría y Ciencias de la Visión, Universitat de València, 46100 Burjassot, Spain Dear editorWe read with interest the article by Sha et al1 in the March 2019 issue. This study evaluated the effects of misalignment axis and undercorrecting cylinder powers on the visual performance of astigmatic people. The aim of this work was mainly to assist eye-care practitioners in reducing the number of toric contact lenses stock-keeping units. The authors analyze …
Do Grading Gray Stimuli Help to Encode Letter Position?
2021
Numerous experiments in the past decades recurrently showed that a transposed-letter pseudoword (e.g., JUGDE) is much more wordlike than a replacement-letter control (e.g., JUPTE). Critically, there is an ongoing debate as to whether this effect arises at a perceptual level (e.g., perceptual uncertainty at assigning letter position of an array of visual objects) or at an abstract language-specific level (e.g., via a level of “open bigrams” between the letter and word levels). Here, we designed an experiment to test the limits of perceptual accounts of letter position coding. The stimuli in a lexical decision task were presented either with a homogeneous letter intensity or with a graded gra…
Stereopsis assessment at multiple distances with an iPad application
2017
[EN] We present a new application for iPad for screening stereopsis at multiple distances that allows testing up to ten levels of stereoacuity at each distance. Our approach is based on a random dot stereogram viewable with anaglyph spectacles. Sixty-five subjects with no ocular diseases, wearing their habitual correction were measured at 3 m and 0.5 m. Results were compared with a standard stereoscopic test (TNO). We found not statistically significant differences between both tests, but our method achieved higher reproducibility. Applications in visual screening programs and to design and use of 3D displays, are suggested. (C) 2017 Elsevier B.V. All rights reserved.
Colorimetric Characterization of Mobile Devices for Vision Applications
2015
Purpose: Available applications for vision testing in mobile devices usually do not include detailed setup instructions, sacrificing rigor to obtain portability and ease of use. In particular, colorimetric characterization processes are generally obviated. We show that different mobile devices differ also in colorimetric profile and that those differences limit the range of applications for which they are most adequate. Methods: The color reproduction characteristics of four mobile devices, two smartphones (Samsung Galaxy S4, iPhone 4s) and two tablets (Samsung Galaxy Tab 3, iPad 4), have been evaluated using two procedures: 3D LUT (Look Up Table) and a linear model assuming primary constan…
A Novel Marking Reader for Progressive Addition Lenses Based on Gabor Holography
2016
PURPOSE Progressive addition lenses (PALs) are marked with permanent engraved marks (PEMs) at standardized locations. Permanent engraved marks are very useful through the manufacturing and mounting processes, act as locator marks to re-ink the removable marks, and contain useful information about the PAL. However, PEMs are often faint and weak, obscured by scratches, partially occluded, and difficult to recognize on tinted lenses or with antireflection or scratch-resistant coatings. The aim of this article is to present a new generation of portable marking reader based on an extremely simplified concept for visualization and identification of PEMs in PALs. METHODS Permanent engraved marks o…
Steerable wavelet transform for atlas based retinal lesion segmentation
2013
International audience; Computer aided diagnosis and follow up can help in prevention and treatment of diabetes and its related complications. Screening of diabetes related disease in the eyes is done by a special low cost fundus camera. A follow up of the patients visiting at di fferent time intervals for screening brings us to the problem of image analysis for change detection and its cost per patient. It is very likely that human annotations for the lesions may be erroneous and often time consuming. Since the ethnic background plays a signi cant role in retinal pigment epithelium, visibility of the choroidal vasculature and overall retinal luminance in patients and retinal images, an eth…