Portable Perimetry Using Eye-Tracking on a Tablet Computer—A Feasibility Assessment

Purpose: Visual field (VF) examination by standard automated perimetry (SAP) is an important method of clinical assessment. However, the complexity of the test, and its use of bulky, expensive equipment makes it impractical for case-finding. We propose and evaluate a new approach to paracentral VF assessment that combines an inexpensive eye-tracker with a portable tablet computer (“Eyecatcher”). Methods: Twenty-four eyes from 12 glaucoma patients, and 12 eyes from six age-similar controls were examined. Participants were tested monocularly (once per eye), with both the novel Eyecatcher test and traditional SAP (HFA SITA standard 24-2). For Eyecatcher, the participant's task was to simply to look at a sequence of fixed-luminance dots, presented relative to the current point of fixation. Start and end fixations were used to determine locations where stimuli were seen/unseen, and to build a continuous map of sensitivity loss across a VF of approximately 20°. Results: Eyecatcher was able to clearly separate patients from controls, and the results were consistent with those from traditional SAP. In particular, mean Eyecatcher scores were strongly correlated with mean deviation scores (r2 = 0.64, P < 0.001), and there was good concordance between corresponding VF locations (∼84%). Participants reported that Eyecatcher was more enjoyable, easier to perform, and less tiring than SAP (all P < 0.001). Conclusions: Portable perimetry using an inexpensive eye-tracker and a tablet computer is feasible, although possible means of improvement are suggested. Translational Relevance: Such a test could have significant utility as a case finding device

Refinement and preliminary evaluation of two tablet-based tests of real-world visual function

PURPOSE: To describe, refine, evaluate, and provide normative control data for two freely available tablet-based tests of real-world visual function, using a cohort of young, normally-sighted adults. METHODS: Fifty young (18-40 years), normally-sighted adults completed tablet-based assessments of (1) face discrimination and (2) visual search. Each test was performed twice, to assess test-retest repeatability. Post-hoc analyses were performed to determine the number of trials required to obtain stable estimates of performance. Distributions were fitted to the normative data to determine the 99% population-boundary for normally sighted observers. Participants were also asked to rate their comprehension of each test. RESULTS: Both tests provided stable estimates in around 20 trials (~1-4 min), with only a further reduction of 14%-17% in the 95% Coefficient of Repeatability (CoR95 ) when an additional 40 trials were included. When using only ~20 trials: median durations for the first run of each test were 191 s (Faces) and 51 s (Search); test-retest CoR95 were 0.27 d (Faces) and 0.84 s (Search); and normative 99% population-limits were 3.50 d (Faces) and 3.1 s (Search). No participants exhibited any difficulties completing either test (100% completion rate), and ratings of task-understanding were high (Faces: 9.6 out of 10; Search: 9.7 out of 10). CONCLUSIONS: This preliminary assessment indicated that both tablet-based tests are able to provide simple, quick, and easy-to-administer measures of real-world visual function in normally-sighted young adults. Further work is required to assess their accuracy and utility in older people and individuals with visual impairment. Potential applications are discussed, including their use in clinic waiting rooms, and as an objective complement to Patient Reported Outcome Measures (PROMs)

Testing a phantom eye under various signal-to-noise ratio conditions using eleven different OCT devices

We compared eleven OCT devices in their ability to quantify retinal layer thicknesses under different signal-strength conditions, using a commercially available phantom eye. We analyzed a medium-intensity 50 µm layer in an identical manner for all devices, using the provided log-scale images and a reconstructed linear-scale tissue reflectivity metric. Thickness measurements were highly comparable when the data were analyzed in an identical manner. With optimal signal strength, the thickness of the 50 µm layer was overestimated by a mean of 4.3 µm in the log-scale images and of 2.7 µm in the linear-scale images

Electron Spin Precession at CEBAF

The nuclear physics experiments at the Thomas Jefferson National Accelerator Facility often require longitudinally polarized electrons to be simultaneously delivered to three experimental halls. The degree of longitudinal polarization to each hall varies as function of the accelerator settings, making it challenging in certain situations to deliver a high degree of longitudinal polarization to all the halls simultaneously. Normally, the degree of longitudinal polarization the halls receive is optimized by changing the initial spin direction at the beginning of the machine with a Wien filter. Herein, it is shown that it is possible to further improve the degree of longitudinal polarization for multiple experimental halls by redistributing the energy gain of the CEBAF linacs while keeping the total energy gain fixed.Comment: 4 pages, 3 figures, to appear in the proceedings of the 18th International Symposium on Spin Physics (SPIN2008

Report of the ANL Technical Advisory Panel on physics with polarized beams and targets

The ZGS is scheduled for shutdown in October 1979; hence, only a limited number of experiments can yet be done. The first part of this report consists of a brief discussion of recent experimental measurements at the ZGS, their implications, and recommendations for future experiments. Areas included are elastic pp and np scattering, low-energy NN scattering, and experiments at large t. An overall summary showing the various parts of the nucleon--nucleon picture is also given. The second part of the report assembles some useful pieces of nucleon--nucleon information frequently used by researchers in this field. 1 figure, 5 tables. (RWR

Updated Report Acceleration of Polarized Protons to 120-150 GeV/c at Fermilab

The SPIN@FERMI collaboration has updated its 1991-95 Reports on the acceleration of polarized protons in Fermilab's Main Injector, which was commissioned by Fermilab. This Updated Report summarizes some updated Physics Goals for a 120-150 GeV/c polarized proton beam. It also contains an updated discussion of the Modifications and Hardware needed for a polarized beam in the Main Injector, along with an updated Schedule and Budget.Comment: 30 pages, 12 figure

Experimental determination of the evolution of the Bjorken integral at low Q^2

We extract the Bjorken integral Gamma^{p-n}_1 in the range 0.17 < Q^2 < 1.10 GeV^2 from inclusive scattering of polarized electrons by polarized protons, deuterons and 3He, for the region in which the integral is dominated by nucleon resonances. These data bridge the domains of the hadronic and partonic descriptions of the nucleon. In combination with earlier measurements at higher Q^2, we extract the non-singlet twist-4 matrix element f_2.Comment: Quoted world data updated. Minor change in some results, Minor rephrasin

Novel computer-based assessments of everyday visual function in people with age-related macular degeneration.

PURPOSE: To test the hypothesis that the performance in novel computer-based tasks of everyday visual function worsens with disease severity in people with non-neovascular age-related macular degeneration. METHODS: Participants with and without non-neovascular age-related macular degeneration (≥60 years, minimum logMAR binocular visual acuity 0.7) performed a series of standard visual function tests and two novel computer-based tasks. In a visual search task, participants had to locate an image of a single real-world object within an array of 49 distractor images. Next, in a series of simulated dynamic driving scenes, participants were asked to identify one or two approaching real-world road signs and then select these road signs from four options. Outcome measures were median response times and total correct responses. RESULTS: Forty-nine participants had no macular disease (n = 11), early/intermediate age-related macular degeneration (n = 16) or geographic atrophy (n = 22). Groups were age-similar with median (interquartile range) logMAR visual acuity of 0.00 (-0.08,0.12), 0.13 (-0.08,0.70) and 0.32 (0.12,0.70) respectively. Median (interquartile range) visual search response times were 1.9 (1.0,2.4), 1.8 (1.1,3.7) and 2.4 (1.2,6.0) seconds respectively. Median (interquartile range) road sign response times (single road signs) were 1.2 (0.4,1.7), 1.5 (0.9,2.8) and 1.8 (1.0,5.5) seconds respectively. Median (interquartile range) road sign response times (double road signs) were 1.7 (0.7,2.4), 2.3 (1.2,3.1) and 2.5 (1.7,6) seconds respectively. Participants with geographic atrophy recorded slower response times in all tasks and over 50% performed outside the normative limit for task performance. There were no significant differences between groups in total correct responses across all tasks. CONCLUSIONS: In a novel computer-based assessment, people with increasing severity of age-related macular degeneration take longer to perform visual search of everyday objects and take longer to identify road signs than those with no age-related macular degeneration. These novel assessments could be useful as patient-relevant, secondary outcomes for clinical trials