Search results for " Vision"
showing 10 items of 2709 documents
A Review of Occlusion as a Tool to Assess Attentional Demand in Driving
2021
Objective The aim of this review is to identify how visual occlusion contributes to our understanding of attentional demand and spare visual capacity in driving and the strengths and limitations of the method. Background The occlusion technique was developed by John W. Senders to evaluate the attentional demand of driving. Despite its utility, it has been used infrequently in driver attention/inattention research. Method Visual occlusion studies in driving published between 1967 and 2020 were reviewed. The focus was on original studies in which the forward visual field was intermittently occluded while the participant was driving. Results Occlusion studies have shown that attentional demand…
<title>Eye movements during silent and oral reading with stabilized versus free head movement and different eye-trackers</title>
2008
Eye movement research of reading has been done on a battery of eye-tracking setups during last decades. We compared reading data of the same group of six students, their eyes were tracked by a video-based helmet-mounted system with the data sampling frequency of 50 Hz and a setup with a chin-rest at 240 Hz. We found that not only the number of fixations may decrease after reading practice, but so does also the mean duration of fixations. In spite of the short duration of saccades, their distributions and changes in them are similarly reported in the two experimental conditions. Lack of significant correlation in the HED data testifies to the result variability due to measurement technique. …
Visual acuity and contrast sensitivity screening with a new iPad application
2016
We present a new iPad application (app) for a fast assessment of Visual Acuity (VA) and Contrast Sensitivity (CS) whose reliability and agreement was evaluated versus a commercial screening device (Optec 6500). The measurement of VA was programmed in the app in accordance with the Amblyopia Treatment Study protocol. The CS was measured with sinusoidal gratings of four different spatial frequencies: 3, 6, 12 and 18 cpd at the same contrast values of the Functional Acuity Contrast Test (FACT) included in the Optec 6500. Forty-five healthy subjects with monocular corrected visual acuities better than 0.2 logMAR participated in the agreement study. Bland-Altman analyses were performed to assess…
Interocular differences in visual quality due to ocular aberrations and scattering in a patient with post-traumatic anisocoria: A case report
2012
AbstractA 41-year-old patient with visual disturbances after an ocular trauma in right eye three years before was carefully analyzed and discussed. No corneal or intraocular sequelae were present. Only a significant anisocoria could be observed. Right eye (RE) achieved a best spectacle-corrected visual acuity (BSCVA) of 0.05 LogMAR with a refraction of +0.50 sphere and −1.25 cylinder. Left eye (LE) achieved a BSCVA of 0.0 LogMAR with a refraction of +0.75 sphere and −1.00 cylinder. In photopic conditions pupil diameter was 4.96mm for RE and 3.02mm for LE whereas in scotopic conditions, these values were 7.45mm and 6.71mm, respectively. More significant levels of higher-order corneal and ocu…
Impact of the pupil size – central optical zone diameter relationship on visual performance in aspheric multifocal contact lenses
2020
Abstract Purpose To determine the impact of different central optical zone diameters (COZDs), obtained from pupil size, on the visual performance of presbyopic subjects fitted with centre-distance simultaneous-image multifocal contact lenses (SIMCLs). Methods Thirty-two presbyopic volunteers, between 45–58 years of age, participated in this prospective, controlled, double-blind study. Subjects were fitted with 5 centre-distance SIMCLs of variable COZD, determined from the measurement of pupil size under photopic light conditions and corresponding to 60, 70, 80, 90 and 100 % of pupil diameter. Subjects visual performance was evaluated through the measurement of distance, intermediate and nea…
Effect of Varying Levels of Glare on Contrast Sensitivity Measurements of Young Healthy Individuals Under Photopic and Mesopic Vision
2018
Contrast sensitivity (CS), the ability to detect small spatial changes of luminance, is a fundamental aspect of vision. However, while visual acuity is commonly measured in eye clinics, CS is often not assessed. At issue is that tests of CS are not highly standardized in the field and that, in many cases, optotypes used are not sensitive enough to measure graduations of performance and visual abilities within the normal range. Here, in order to develop more sensitive measures of CS, we examined how CS is affected by different combinations of glare and ambient lighting in young healthy participants. We found that low levels of glare have a relatively small impact on vision under both photopi…
The Impact on Vision of Aspheric to Spherical Monofocal Intraocular Lenses in Cataract Surgery
2013
Purpose To provide a summary of the impact on vision of an aspheric intraocular lens (IOL) compared with a spherical IOL in cataract surgery. Design Systematic review with meta-analysis. Participants Patients from published randomized controlled trials (RCTs) of cataract surgery with aspheric compared with spherical monofocal IOL implantation. Methods We systematically searched the peer-reviewed literature in MEDLINE, EMBASE, Web of Science, BIOSIS, and the Cochrane Library according to the Cochrane Collaboration method to identify relevant RCTs. The inclusion criteria were RCTs on cataract surgery comparing the use of aspheric versus spherical IOL implantation that assessed visual acuity, …
Use in clinical practice of an automated screening method of diabetic retinopathy that can be derived using a diagnostic artificial intelligence syst…
2020
Abstract Background and Objective To compare the diagnostic performance of an autonomous diagnostic artificial intelligence (AI) system for the diagnosis of derivable diabetic retinopathy (RDR) with manual classification. Materials and Methods Patients with type 1 and type 2 diabetes participated in a diabetic retinopathy (RD) screening program between 2011–2012. 2 images of each eye were collected. Unidentifiable retinal images were obtained, one centered on the disc and one on the fovea. The exams were classified with th e autonomous AI system and manually by anonymous ophthalmologists. The results of the AI system and manual classification were compared in terms of sensitivity and specif…
Stereoscopic Viewing Enhances Visually Induced Motion Sickness but Sound Does Not
2012
Optic flow in visual displays or virtual environments often induces motion sickness (MS). We conducted two studies to analyze the effects of stereopsis, background sound, and realism (video vs. simulation) on the severity of MS and related feelings of immersion and vection. In Experiment 1, 79 participants watched either a 15-min-long video clip taken during a real roller coaster ride, or a precise simulation of the same ride. Additionally, half of the participants watched the movie in 2D, and the other half in 3D. MS was measured using the Simulator Sickness Questionnaire (SSQ) and the Fast Motion Sickness Scale (FMS). Results showed a significant interaction for both variables, indicatin…
Spectral decomposition of RR-variability obtained by an open loop parametric model for the diagnosis of neuromediate syncope
2002
The role of the cardiovascular regulatory mechanism in patients with neuromediate syncope (NS) is poorly understood. The aim of this study was to accomplish continuous non-invasive analysis of the baroreflex mechanism in patients during a head-tip tilt-table test (HTT) using an open-loop autoregressive model with exogenous input. The model describes the causal dependence of the RR interval on the systolic arterial pressure (SAP) variability. Thus, RR variability results as the linear composition of SAP-dependent (Pdep) and SAP-independent parts of the RR power (P). Further, the model allows the estimation of the baroreflex gain using the modulus of the transfer function (G) from SAP to RR i…