Attenuation of choroidal tickness in patients with Alzheimer disease: evidence from an Italian prospective study

INTRODUCTION: To compare the 12-month choroidal thickness (CT) change between Alzheimer disease (AD) patients and normal subjects. METHODS: In this prospective, observational study, 39 patients with a diagnosis of mild to moderate AD and 39 age-matched control subjects were included. All the subjects underwent neuropsychological (Mini Mental State Examination, Alzheimer disease Assessment Scale-Cognitive Subscale, and the Clinical Dementia Rating Scale) and ophthalmological evaluation, including spectral domain optical coherence tomography, at baseline and after 12 months. CT was measured manually using the caliper tool of the optical coherence tomography device. RESULTS: After 12 months, AD patients had a greater reduction of CT than controls (P≤0.05, adjusted for baseline CT, age, sex, axial length, and smoking). DISCUSSION: CT in patients with AD showed a rate of thinning greater than what could be expected during the natural course of aging

Macular ganglion cell layer thickness after macula-off rhegmatogenous retinal detachment repair: scleral buckling versus pars plana vitrectomy

(1) Background: We evaluated macular ganglion cell layer-inner plexiform layer (GCL-IPL) thickness in patients with primary macula-off rhegmatogenous retinal detachment (RRD) treated with scleral buckling (SB) or pars plana vitrectomy (PPV) using spectral domain optical coherence tomography (SD-OCT). (2) Methods: In this retrospective, observational study, we reviewed the medical records of patients undergoing SB or PPV surgery for macula-off RRD. SD-OCT was performed at three and 12 months after surgery. The central and parafoveal GCL-IPL thicknesses in treated eyes were compared with those of healthy fellow eyes. OCT measurements between the SB and PPV group were also compared using the analysis of covariance. (3) Results: Seventy-one eyes of 71 patients with a mean age of 61.2 ± 11.7 years were included. The parafoveal GCL-IPL thickness of the PPV group was significantly reduced, with respect to fellow eyes, at three and 12 months (p < 0.01). After adjusting for age, axial length, spherical equivalent, RD extent, preoperative intraretinal cysts, duration of symptoms and postoperative IOP, the parafoveal GCL-IPL thickness in the PPV group was significantly reduced with respect to the SB group, both at three and 12 months (F = 11.45, p = 0.001 and F = 12.37, p = 0.001, respectively). (4) Conclusions: In conclusion, the GCL-IPL is reduced in thickness in eyes with macula-off RRD treated with vitrectomy and is significantly thinner compared to eyes undergoing scleral buckling surgery

Quantitative Approach for the Analysis of Fusional Convergence Using Eye-Tracking and SacLab Toolbox

Fusional vergence is a disjunctive movement of the eyes that is made in order to obtain single vision. (e aim of the study was to provide a quantitative and objective approach for analyzing the fusional convergence response using eye tracking (ET) technology and automatic data analysis provided by the intuitive SacLab toolbox previously developed by our group. We evaluated the proposed approach in a population of 26 subjects with normal binocular vision, who were tested with base-out prisms (magnitudes 4\u394, 6\u394, and 10\u394) in order to elicit fusional convergence response. Eye movements were recorded using the Viewpoint ET and analyzed using SacLab. Parameters describing both the vergence and the version components of the fusional response (convergence duration, CD; peak convergence velocity, PCV; number of intrusive saccades, NS; and mean saccadic amplitude, MSA) were automatically calculated and provided to clinicians for an objective evaluation. Results showed that the number of subjects achieving fusional convergence decreased with prism magnitude. For subjects achieving fusion CD and PCV increased significantly (p < 0.05) when increasing the prism magnitude. For NS and MSA, there were no significant changes when passing to 6\u394, but a significant increase resulted when passing to 10\u394 (p < 0.05). Noninvasive ET associated with the intuitive SacLab toolbox may represent a valid option to objectively characterize the fusional vergence response in clinical setting. (e analysis may be extended to patients with vergence disorders

Optical coherence tomography evidence of macular ganglion cell-inner plexiform layer thinning in eyes with subretinal drusenoid deposits

Background/Objectives: The purpose of this study was to evaluate macular ganglion cell layer-inner plexiform layer (GCL-IPL) and choroidal thickness in early age-related macular degeneration (AMD) in eyes with subretinal drusenoid deposits (SDD). Subjects/Methods: Comprehensive ophthalmological examination was performed. Near infrared reflectance and raster images using enhanced depth imaging were acquired with spectral domain optical coherence tomography. Drusen and SDD were diagnosed based on raster scans and near infrared reflectance. GCL-IPL maps were generated with automated segmentation and choroidal thickness maps were obtained by manually delineating the choroid-scleral boundary. Results: Forty-eight eyes from 48 patients (mean age 77.5 ± 5.7, range 68–90 years) with a diagnosis of early AMD and 42 eyes of 42 age-matched control subjects (mean age 76.9 ± 5.7, range 67–88 years) were included. Of these, 28 eyes (58.3%) had drusen alone, 4 eyes (8.3%) had SDD alone, and 16 eyes (33.3%) had drusen associated with SDD. Compared with controls, average choroidal thickness was significantly decreased in AMD eyes (P < 0.05). There was no significant difference in choroidal thickness in eyes with SDD with respect to those with drusen alone. GCL-IPL thickness was reduced in an annular pattern at the 3 and 6 mm macular areas in AMD patients with respect to controls (P < 0.05). GCL-IPL thickness at 3 mm was significantly reduced in eyes with SDD with respect to those with drusen alone (P = 0.03). Conclusions: The GCL-IPL is reduced in thickness with an annular pattern in early AMD and is significantly thinner in eyes with SDD

RE L(3) x-ray absorption study of REO(1-x)F(x)FeAs (RE = La, Pr, Nd, Sm) oxypnictides RID A-4797-2009

Rare earth L(3)-edge x-ray absorption near-edge structure (XANES) spectroscopy has been used to study REOFeAs (RE = La, Pr, Nd, Sm) oxypnictides. The Nd L(3) XANES due to the 2p(3/2) -> 5 epsilon d transition shows a substantial change in both white line (WL) spectral weight and the higher energy multiple scattering resonances with the partial substitution of O by F. A systematic change in the XANES features is seen due to varying lattice parameters with ionic radius of the rare earth. On the other hand, we hardly see any change across the structural phase transition. The results provide timely information on the local atomic correlations showing the importance of the local structural chemistry of the REO spacer layer and interlayer coupling in the competing superconductivity and itinerant striped magnetic phase of the oxypnictides

Retinal nerve fibre layer thickness changes in alzheimer's disease: results from a 12-month prospective case series

PURPOSE: To compare the 12-month peripapillary retinal nerve fibre layer (pRNFL) thickness change between AD patients and normal subjects. METHODS: In this prospective case series, thirty-six patients with a diagnosis of mild to moderate AD and 36 age-matched control subjects were included. All the subjects underwent neuropsychological (MMSE, ADAS-Cog and CDR) and ophthalmological evaluation, including spectral domain optical coherence tomography (SD-OCT), at baseline and after 12 months. RESULTS: Compared with controls, AD patients had a significant reduction of the total pRNFL thickness, as well as the pRNFL thickness of the inferior and superior quadrants (p=0.04, p=0.001, and p=0.01, respectively, adjusted for baseline pRNFL measurement, age, gender, and axial length). Correlation analysis showed a significant relationship between inferior pRNFL thickness change and ADAS-Cog scores change (r=-0.35, p=0.02) as well as CDR scores at 12 months (r=-0.39, p=0.008). CONCLUSIONS: Compared with controls, AD patients had a significant reduction in pRNFL thickness over a period of 12 months. The pRNFL reduction was more prominent in the inferior quadrant and paralleled patient's cognitive decline

SacLab: A toolbox for saccade analysis to increase usability of eye tracking systems in clinical ophthalmology practice

Purpose Many open source software packages have been recently developed to expand the usability of eye tracking systems to study oculomotor behavior, but none of these is specifically designed to encompass all the main functions required for creating eye tracking tests and for providing the automatic analysis of saccadic eye movements. The aim of this study is to introduce SacLab, an intuitive, freely-available MATLAB toolbox based on Graphical User Interfaces (GUIs) that we have developed to increase the usability of the ViewPoint EyeTracker (Arrington Research, Scottsdale, AZ, USA) in clinical ophthalmology practice. Methods SacLab consists of four processing modules that enable the user to easily create visual stimuli tests (Test Designer), record saccadic eye movements (Data Recorder), analyze the recorded data to automatically extract saccadic parameters of clinical interest (Data Analyzer) and provide an aggregate analysis from multiple eye movements recordings (Saccade Analyzer), without requiring any programming effort by the user. Results A demo application of SacLab to carry out eye tracking tests for the analysis of horizontal saccades was reported. We tested the usability of SacLab toolbox with three ophthalmologists who had no programming experience; the ophthalmologists were briefly trained in the use of SacLab GUIs and were asked to perform the demo application. The toolbox gained an enthusiastic feedback from all the clinicians in terms of intuitiveness, ease of use and flexibility. Test creation and data processing were accomplished in 52±21 s and 46±19 s, respectively, using the SacLab GUIs. Conclusions SacLab may represent a useful tool to ease the application of the ViewPoint EyeTracker system in clinical routine in ophthalmology

Gaze Trajectory Index (GTI): A novel metric to quantify saccade trajectory deviation using eye tracking

Background: Many different indexes have been proposed to quantify saccade curvature based on geometric properties of the saccade trajectory projected on the 2D plane. We introduce the Gaze Trajectory Index (GTI), a novel metric to quantify saccade trajectory deviation based on calculation of the rotational eye movements performed in 3D space while following a 2D saccade trajectory recorded with eye tracking (ET). Methods: We provided a description of GTI calculation. In 13 subjects with normal binocular vision we assessed GTI in single-target tests, then we evaluated GTI against previously proposed metrics (Maximum Deviation,MD; Area Curvature,AC; Quadratic Curvature,QC; Initial Direction,ID) using a distractor paradigm that elicited two types of saccade deviations, i.e.\u201cinner-curved\u201d and \u201couter-curved\u201d saccades. Results: In single-target tests GTI showed that saccade curvature was significantly higher for oblique than for vertical saccades (0.86\ub0\ub10.32 vs 0.55\ub0\ub10.60,p < 0.05) and higher for vertical than for horizontal saccades (0.55\ub0\ub10.60 vs 0.23\ub0\ub10.17,p < 0.05), in accordance with previous studies. In distractor-based tests, for inner-curved saccades, GTI strongly correlated with MD (r = 0.965,p < 0.01), AC (r = 0.940,p < 0.01), QC (r = 0.866,p < 0.01), and Principal Component Analysis (PCA) confirmed that all these metrics reflect the same underlying phenomenon. For outer-curved trajectories, GTI showed poor correlation with MD and AC (r = 0.291 and 0.416,p < 0.01), however PCA included the three metrics in the same first component group. For outer-curved trajectories, GTI was the only metric showing strong correlation (r = 0.950,p < 0.05) with the overshoot degree of the trajectory. Conclusion: The novel GTI seems to have adjunctive potential, particularly for outer-curved trajectories, in the estimation of the absolute amount of saccade trajectory deviation

Study of fusional convergence using eye tracking: preliminary results on subjects with normal binocular vision

Purpose: In the field of ophthalmology, vision researchers use eye tracking to study oculomotor behavior, cognitive visual function and vision deficiencies. Fusional vergence is a disjunctive movement of the eyes that is made in order to obtain single vision with two eyes. Fusional vergence disorders are often associated with the most common forms of strabismus. The aim of the study was to characterize fusional convergence response in subjects with normal binocular viewing by using an eye tracking system. Methods: Base-out horizontal prisms of 4 and 6 diopters were used to elicit fusional convergence of the right eye in 11 subjects with normal binocular vision. Eye movements were continuously recorded using the Viewpoint infrared video eye tracker (Arrington Research, Scottsdale, AZ, USA) and custom software was developed to automatically analyze off-line the saccadic response (gaze angle and angular velocity). The Fusional Convergence Amplitude (FCA) was calculated by subtracting the baseline position of the right eye (i.e. before the introduction of the prism) from the maximum saccadic excursion of the right eye during the disconjugate eye movements in the vergence phase (Figure 1.a). Results: The typical eye-movement response in subjects achieving the fusional convergence was a preliminary saccadic movement of both eyes (version phase) followed by a convergence movement with the eyes moving towards each other to achieve single vision (vergence phase) (Figure 1). Eye tracking recordings showed that 2 patients were not able to achieve fusion with neither 4 nor 6 diopters prisms. Fusion was achieved in 8 subjects when using the 4 diopters prism and only in 6 subjects when using 6 diopters prism. One patient was excluded from the analysis because the saccadic movements were highly affected by blink artifacts. The FCA varied from 2.2\ub0\ub10.2 to 3.0\ub0\ub10.2 when increasing prism diopters from 4 to 6 (Figure 2). Conclusions: The fusional convergence can be accurately studied and evaluated using an eye tracking system. Preliminary results on subjects with normal vision showed that when increasing the prism diopters the fusional convergence ability decreases

Influence of textured backgrounds on fusional vergence: preliminary results using an eye tracker

Purpose: The vergences ensure and maintain binocular fixation and binocular vision. The amplitude of vergences depends on many factors, one of which is the amount of fusible material on the binocular field of vision. In casual seeing the whole surface of the two retinas is exposed to similar stimuli and the conditions for motor fusion should be optimal. The retinal periphery is a powerful factor in production of fusional movements and makes an important contribution to stabilization of relative position of the eyes. The purpose of the study was to evaluate whether the presence of a textured background in the visual stimulus may influence the convergence fusional response. Methods: Eleven subjects with normal binocular vision underwent fusional disparity stimuli: a base-out prism of 6 diopters was placed in front of the right eye to elicit disparity. Eye movements were continuously recorded using the Viewpoint infrared video eye tracker (Arrington Research, Scottsdale, AZ, USA) and a custom software was developed to automatically analyze off-line the saccadic response (gaze angle). Each subject was examined twice, once by presenting the visual stimulus (black dot) on a white background, then by presenting the same stimulus on a textured background (Figure 1). The order of presentation of the two tests was randomly chosen. Results: Eye tracking recordings showed a typical pattern for the fusional behavior: a preliminary saccadic movement of both eyes (version phase) and a following convergence movement with the eyes moving towards each other to achieve single vision (vergence phase) (Figure 2.a). When presenting the stimulus on the white background only 6 subjects (54%) achieved fusional convergence. This number increased up to 9 subjects (82%) when presenting the same stimulus on the textured background (Figure 2.b). Conclusions: The fusional vergence response can be accurately studied and evaluated using an eye tracker. In subjects with normal binocular vision the presence of a textured background seems to facilitate the fusional convergence ability