Fundamentals of Presbyopia: visual processing and binocularity in its transformation

Background:The accommodation has considerable interactions with the pupil response,vergence response and binocularity.The transformation of visual reception processing and the changes of the binocular cooperation during the presbyopia development are still poorly studied.So,the regularities of visual system violation in the presbyopia formation need to be characterized.This study aims to reveal the transformation of visual reception processing and to determine the role of disturbances in binocular interactions in presbyopia formation.Methods:This study included 60 people with emmetropic refraction,uncorrected distance visual acuity 1.0 or higher(decimal scale),normal color perception,without concomitant ophthalmopathology.The first group consisted of 30 people(from 18 to 27 years old)without presbyopia,the second cohort comprised 30 patients(from 45 to 55 years old)with presbyopia.The eyeball anatomy and optics were evaluated using ultrasound biomicroscopy,aberrometry,and pupillometry.The functional state of the visual system was investigated under monocular and binocular conditions.The registration of the disparate fusional reflex limits was performed by the original technic using a diploptic device which facilitated investigation of the binocular interaction under natural conditions without the accommodation response,but with the different vergence load.The disparate fusional reflex was analyzed using the proximal and distal fusion borders,and the convergence and divergence fusion borders.The calculation of the area of binocularity field was performed in cm2.Results:The presbyopia formation is characterized by a change in an intraocular anatomy,optics,visual processing,and binocularity.The processes of binocular interaction inhibition make a significant contribution to the misalignment of the visual perception.The modification of the proximal,distal and convergence fusion borders was determined.It was revealed that 87%of the presbyopic patients had binocularity shortage,whereas the reduction of binocularity field area in extreme grade was seen in 6%of cases.Conclusions:The presbyopia formation is accompanied by a significant reorganization of the visual system activity and by the creation of the new visual processing interactions.These data may be useful in presbyopia surgery.

VISUAL OBSERBATION OF HCFC141b GAS HYDRATE FORMATION/DECOMPOSITION PROCESS OUTSIDE OF A TUBE

In order to design a kind of heat exchanger suitable to the indirect-touched gas hydrate cool storage vessel, a visual observation of HCFC141b gas hydrate formation/decomposition process was presented through a self-designed small-scale visualization apparatus of gas hydrate cool storage. Based on the shooted photos and recorded temperatures, the formation/decomposition process of HCFC141b are described, some characteristics are concluded, and some suggestions of designing heat exchanger are indicated according to the specific characteristics of HCFC141b gas hydrate formation/decomposition process.

Visual order of Chinese ink paintings

Visual order is one of the key factors influencing the aesthetic judgment of artworks.This paper reports the results of evaluating the influence of extracted features on visual order in Chinese ink paintings,using a regression model.We use nine contemporary artists’paintings as examples and extract features related to the visual order of their paintings.A questionnaire survey is conducted to collect people’s rating scores on the visual order.Via regression modeling,our research analyzes the significance of each feature and validates the influences of the features on the visual order.

Regional volume changes of the brain in migraine chronification

The pathophysiology of migraine is complex.Neuroimaging studies reveal functional and structural changes in the brains of migraine patients.We sought to explore regional volume differences in intracranial structures in patients with episodic and chronic migraine.Sixteen episodic migraine patients,16 chronic migraine patients,and 24 normal controls were recruited and underwent 3.0 T MRI scanning.The volumes of 142 brain regions were calculated by an automatic volumetric algorithm and compared with clinical variables.Results demonstrated that the volumes of specific regions in the frontal and occipital lobes,and the right putamen,were increased and the volume of the fourth ventricle was decreased in the episodic migraine patients compared with controls.The volumes of the left basal forebrain,optic chiasm,and,the fourth ventricle were decreased in the chronic migraine patients,while the occipital cortex and the right putamen were larger.Compared to episodic migraine patiants,chronic migraine patients displayed larger left thalamus and smaller frontal regions.Correlation analysis showed that headache frequency was negatively correlated with the volume of the right frontal pole,right lateral orbital gyrus,and medial frontal lobes and positively correlated with the volume of the left thalamus.The sleep disturbance score was negatively correlated with the volume of the left basal forebrain.This suggests that migraine patients have structural changes in regions associated with pain processing and modulation,affective and cognitive processing,and visual perception.The remodeling of selective intracranial structures may be involved in migraine attacks.This study was approved by the Ethics Committee of Chinese PLA General Hospital(approval No.S2018-027-02)on May 31,2018.

AB003.Pulvinar mediates the transmission of gamma and alpha oscillatory bandsbetween areas 17 and 21a

Background:Cortical activity across the visual hierarchy has different oscillatory ranges.While 25-90 Hz gamma band influences the feedforward processing,6-13 Hz alpha band travels in the feedback direction.Furthermore,gamma band acts in supragranular layers,whereas alpha range is localized in infragranular cortical layers.Is the pulvinar,the largest visual thalamic nucleus,mediating this oscillatory cortical coupling?We investigated this question by inactivating pharmacologically the pulvinar in cats and analyzing its impact on the oscillatory flow of neural activity in the visual cortex.Methods:Extracellular responses to full-field 100%contrast gratings were recorded in cortical areas 17 and 21a,from anesthetized cats using linear silicon probes before,during and after the pulvinar inactivation(injection of GABA solution).Visual stimuli were presented in one selected direction.Local field potentials(LFPs)were obtained from low-pass filtering of raw recordings.Wavelet and Granger causality analyses were performed on LFPs to determine the oscillatory coupling between cortical layers.Results:We found that cortical oscillatory activity was enhanced during LPl inactivation.These increases were observed for alpha and gamma bands in areas 17 and 21a.In area 17,alpha and gamma bands significantly increased in layers IV,V,and IV.In area 21a,this increase was observed in all layers except layer I,with a substantial increase of gamma activity in layer IV.Granger causality analysis showed that the pulvinar inactivation caused enhanced of feedforward gamma band signals from area 17(layer III)to area 21a(layer IV).For the feedback coupling,the alpha band rose from area 21a(layer V)to area 17(layers III,V,and VI).Conclusions:Our findings suggest that the pulvinar mediates the cortical oscillatory transmission between areas 17 and 21a.In particular,during the visual stimulation,the pulvinar mediates,to some extent,the bottom-up regulation from layer III of area 17 to layer IV in area 21a.Furthermore,the LPl regulates the feedback directionality of the alpha band from layer V in area 21a to layers II,V,and VI in area 17.These results contribute to our understanding of the mechanism underlying the oscillatory coupling of the feedforward and feedback processing throughout the visual cortical hierarchy.

Vernier But Not Grating Acuity Contributes to an Early Stage of Visual Word Processing

The process of reading words depends heavily on efficient visual skills, including analyzing and decomposing basic visual features. Surprisingly, previous reading-related studies have almost exclusively focused on gross aspects of visual skills, while only very few have investigated the role of finer skills. The present study filled this gap and examined the relations of two finer visual skills measured by grating acuity（the ability to resolve periodic luminance variations across space） and Vernier acuity（the ability to detect/discriminate relative locations of features） to Chinese character-processing as measured by character form-matching and lexical decision tasks in skilled adult readers. The results showed that Vernier acuity was significantly correlated with performance in character form-matching but not visual symbol formmatching, while no correlation was found between grating acuity and character processing. Interestingly, we found no correlation of the two visual skills with lexical decisionperformance. These findings provide for the first time empirical evidence that the finer visual skills, particularly as reflected in Vernier acuity, may directly contribute to an early stage of hierarchical word processing.

INTRINSIC OPTICAL SIGNAL IMAGING OF RETINAL ACTIVITY IN FROG EYE

Using a near-infrared(NIR)light flood-illumination imager equipped with a high-speed(120 Hz)CCD camera,we demonstrated optical imaging of stimulus-evoked retinal activity in isolated,but intact,frog eye.Both fast and slow transient intrinsic optical signals(IOSs)were observed.Fast optical response occurred immediately after the stimulus onset,could reach peak magnitude within 100 ms,and correlated tightly with ON and OFF edges of the visible light stimulus;while slow optical response lasted a relatively long time(many seconds).High-resolution images revealed both positive(increasing)and negative(decreasing)IOSs,and dynamic optical change at individual CCD pixels could often exceed 10%of the background light intensity.Our experiment on isolated eye suggests that further development of fast,high(sub-cellular)resolution fundus imager will allow robust detection of fast IOSs in vivo,and thus allow noninvasive,three-dimensional evaluation of retinal neural function.

Self Localization Method Using Parallel Projection Model for Mobile Sensor in Navigation Applications

This paper presents a novel self localization method using parallel projection model for mobile sensor in navigation applications. The algorithm estimates the coordinate and the orientation of mobile sensor using projected references on visual image. The proposed method considers the lens non-linearity of the camera and compensates the distortion by using a calibration table. The method determines the coordinates and orientations with iterative process, which is very accurate with low computational demand. We identify various sources of error on the coordinate and orientation estimations, and present both static sensitivity analysis of the algorithm and dynamic behavior of the mobile sensor. The algorithm can be utilized in mobile robot navigation as well as positioning application where accurate self localization is necessary.

Water Resources Operation and Management Model and Its Simulation Process Research

Based on the status quantity of water resources in Xi′an region, a commentary on many math models is given for water resources operation and management, and the visual model is provided to solve practical problems. In this model, the information for decision is visible in GIS (Geographic Information Systems) and topological figures. With object orientation methods, the objects are described in proprieties, methods, relations and time periods. The simulation process of the model is developed with Delphi and MapInfo, and the real decision scheme could be examined and practice decision process can be simulated from which. Decision analysis conducted from visual conditions is believable. The exploration to visual model is a beginning of practice research, much more study of which still needs to do.