Search results for "lcsh:Ophthalmology"
showing 10 items of 82 documents
Changes of the eye optics after iris constriction☆
2010
Purpose: To evaluate the possible change in the optics of the human eye after iris constriction. Methods: Ocular aberrations were measured under natural viewing conditions in 26 eyes. The measured eyes fixated on a dim target while the contralateral eye was either occluded (so the measured eye had a large pupil) or highly illuminated (so the measured eye had a small pupil). The measured eyes fixated to a dim target placed 0.5 D beyond the subject’s far point. Zernike values obtained in both situations were compared within the same pupil diameter corresponding to the one obtained under the high illumination condition. Results: Significant variation in some aberration coefficients were found …
Visual and ocular effects from the use of flat-panel displays
2016
AIM: To evaluate the prevalence of eye symptoms in a non-presbyopic population of video display unit (VDU) users with flat-panel displays. METHODS: One hundred and sixteen VDU users with flat-panel display from an urban population participated in the study; their ages ranging from 20 to 34y. There were 60 females and 56 males. An eye examination to rule out the presence of significant uncorrected refractive errors, general binocular dysfunctions and eye conditions was carried out. In order to determine and quantify the type and nature of eye symptoms, participants were asked to answer written questionnaire and the results were grouped by gender, age and number of hours a day spent using a V…
Classification of SD-OCT Volumes Using Local Binary Patterns: Experimental Validation for DME Detection
2016
International audience; This paper addresses the problem of automatic classification of Spectral Domain OCT (SD-OCT) data for automatic identification of patients with Diabetic Macular Edema (DME) versus normal subjects. Optical Coherence Tomography (OCT) has been a valuable diagnostic tool for DME, which is among the most common causes of irreversible vision loss in individuals with diabetes. Here, a classification framework with five distinctive steps is proposed and we present an extensive study of each step. Our method considers combination of various pre-processings in conjunction with Local Binary Patterns (LBP) features and different mapping strategies. Using linear and non-linear cl…
Spatio-temporal Contrast Sensitivity in the Cardinal Directions of the Colour Space. A Review
2010
AbstractWe review the psychophysics of the spatio-temporal contrast sensitivity in the cardinal directions of the colour space and their correlation with those neural characteristics of the visual system that limit the ability to perform contrast detection or pattern-resolution tasks. We focus our attention particularly on the influence of luminance level, spatial extent and spatial location of the stimuli - factors that determine the characteristics of the physiological mechanisms underlying detection. Optical factors do obviously play a role, but we will refer to them only briefly. Contrast sensitivity measurements are often used in clinical practice as a method to detect, at their early …
Spotlight on fundus autofluorescence
2018
Ana M Calvo-Maroto,1 Alejandro Cerviño2 1Department of Ophthalmology, Clínica Universidad de Navarra, University of Navarra, Madrid, Spain; 2Optometry Research Group, Department of Optics and Optometry and Vision Sciences, University of Valencia, Valencia, Spain Abstract: Fundus autofluorescence (FAF) imaging is based on the fluorescence from ocular endogenous fluorophores located in the retinal pigment epithelium and choroid, mainly lipofuscin and melanin. It is a noninvasive technique that provides information about the spatial distribution of lipofuscin/melanin and retinal pigment epithelium health status. An overview about the fluorophores responsible for FAF imaging and t…
Prevalence of visual impairment and refractive errors in an urban area of Mexico
2019
AIM: To determine the distribution of refractive errors in a school-age population in Quintana Roo (Mexico) in the framework of an international cooperation campaign for the prevention of blindness. METHODS: A sample of 2647 school-age children (ranging from 5 to 14 years old) with a mean age of 9.1±1.9 years old were tested by trained volunteers for distance visual acuity (VA) and refractive errors. The first screening examination included uncorrected distance visual acuity (UDVA) and VA with a +2.00 D lens. Inclusion criteria for a second complete cycloplegic eye examination performed by an optometrist were UDVA <20/25 (0.10 logMAR or 0.8 decimal) and/or VA with +2.00 D ≥20/25. RESULTS: A…
Retinal Straylight Before and After Penetrating Keratoplasty in an Eye with a Post-Herpetic Corneal Scar
2008
Objetivo: Estudio in vivo de la luz dispersa que alcanza la retina en un paciente antes y despues de someterse a una queratoplastia penetrante (o sus siglas en ingles, PKP). Metodos: En un paciente varon de 65 anos con una ulcera corneal herpetica se midio la proporcion de luz dispersa que alcanza la retina tanto antes como despues de una PKP, utilizando para ello un metodo psicometrico denominado "de comparacion por compensacion" («Compensation comparison method», C-Quant straylightmeter, Oculus GmbH, Alemania). Resultados: La cantidad de luz dispersa que alcanza la retina medida antes de la cirugia fue elevada en comparacion con los valores obtenidos en estudios previos en sujetos normale…
Proteome alterations in aqueous humour of primary open angle glaucoma patients.
2019
Aim To unravel the primary open angle glaucoma (POAG) related proteomic changes in aqueous humour (AH). Methods Totally 35 patients listed for cataract surgery (controls: n=12, age: 67.4±13.6y) or trabeculectomy for POAG (n=23, age: 72.5±8.3y) were included. AH samples of those patients were obtained during cataract surgery or trabeculectomy. AH samples were subsequently pooled into the experimental groups under equal contribution in terms of protein amount of each individual patient. Protein samples were analyzed by a linear trap quadrupol Orbitrap Mass Spectrometry device with an upstream liquid chromatography system. The obtained raw data were analyzed using the Maxquant proteome softwar…
Decreased Perifoveal Sensitivity Detected by Microperimetry in Patients Using Hydroxychloroquine and without Visual Field and Fundoscopic Anomalies
2015
Purpose. To evaluate the usefulness of microperimetry in the early detection of the ocular anomalies associated with the use of hydroxychloroquine.Methods. Prospective comparative case series study comprising 14 healthy eyes of 7 patients (group A) and 14 eyes of 7 patients under treatment with hydroxychloroquine for the treatment of rheumatologic diseases and without fundoscopic or perimetric anomalies (group B). A comprehensive ophthalmological examination including microperimetry (MP) and spectral-domain optical coherence tomography was performed in both groups.Results. No significant differences were found in mean MP foveal sensitivity between groupsP=0.18. However, mean MP overall sens…
Pilot Study on Visual Function and Fundus Autofluorescence Assessment in Diabetic Patients.
2015
Purpose. Evaluate optimized fundus autofluorescence (FAF) imaging in early stages of diabetic retinopathy (DR) and relate findings with conventional colour fundus imaging and visual function in diabetic patients and control subjects.Materials and Methods. FAF and colour images were obtained using the CR-2 Plus digital nonmydriatic retinal camera in seven diabetic patients and thirteen control subjects. Visual-Functioning Questionnaire-25 (VFQ-25) and Diabetes Self-Management Questionnaire (DSMQ) were used to assess the quality of life and diabetes self-care. Contrast sensitivity function (CSF) was evaluated with the Vistech 6500 chart.Results. FAF and optimized-FAF imaging showed more retin…